Rozprawy doktorskie na temat „Paget's disease of bone”

Chapter 3 describes the results of mutation screening of a candidate gene, SQSTM1, from one of the linkage regions implicated in the pathogenesis of PDB in families of mainly British descent.  Seven mutations that segregated with the disease were identified and all clustered in the ubiquitin-associated (UBA) domain of the protein. In Chapter 4, an association study and haplotype analysis was conducted in PDB families using SNPs in SQSTM1.  This revealed that the most common SQSTM1 mutation was predominantly carried on one of two common haplotype backgrounds, suggesting that a strong founder effect exists in this population.  The P392L mutations occurred on the same haplotype background in sporadic cases as in the PDB families, indicating that many ‘sporadic’ PDB cases may have occult familial PDB. A syndrome of PDB associated with inclusion body myopathy and dementia has recently been shown to be caused by mutations that cluster in the CDC48 domain of the VCP gene.  In Chapter 5, the VCP gene was screened for mutations in familial PDB and an association study was conducted in patients with sporadic PDB.  No mutations in this gene were found in the PDB families.  Haplotype analysis of a region spanning this gene also failed to support the involvement of polymorphisms in this gene in determining risk of sporadic PDB. In Chapter 6, genome-wide linkage analysis was conducted in PDB families without SQSTM1 mutations.  This revealed significant evidence of linkage at a locus on chromosome 10p13 (PDB6).  All families involved in this analysis were found to have a high likelihood of linkage at this locus.

In Chapter 4, I investigated the roles of the RANK signalling partners RANK ligand (RANKL) and osteoprotegerin (OPG) in the pathogenesis of sporadic and familial PDB. One polymorphism in the RANK gene and five polymorphisms in the OPG gene were examined in sporadic PDB cases and in sex- and age-matched controls. No allele-disease or genotype-disease association was observed for the RANKL polymorphism, suggesting RANKL is not directly involved in susceptibility to sporadic PDB. Genotypes at two OPG polymorphisms did significantly predict disease status in individuals affected with sporadic PDB, suggesting a role for OPG in the pathogenesis of sporadic PDB. The five OPG polymorphisms were also examined in families affected with PDB. No evidence was found to either suggest or exclude the involvement of any of the OPG polymorphisms in familial PDB. In Chapter 5, I performed a genome-wide search for PDB susceptibility loci in families with inherited PDB. Three regions of potential linkage were identified at 2q36, 5q35 and 10p11. Fine mapping was performed for the candidate region on chromosome 5q35, and eight families with a high probability of linkage to 5q35 were identified. In seven of the families, a shared haplotype transmitted only with affected family members was present. The shared haplotype varied between families and no common allele existed in the seven families for any of the nine markers studied. However, one area of shared haplotype occurred in all seven families across three of the markers, supporting evidence for a susceptibility gene for PDB on 5q35 in these families and narrowing the candidate region. In summary, this study has further highlighted the importance of genetic heterogeneity in the pathogenesis of PDB, excluding the previously identified PDB2 susceptibility locus and identifying three novel regions potentially harbouring susceptibility loci in the families studied. This study has also further defined the role of members of the RANK signalling pathway in the pathogenesis of familial and sporadic PDB.

Paget's disease of the bone is a skeletal disorder of unknown cause. This disease is characterised by excessive and abnormal bone remodelling brought about by increased bone resorption followed by disorganised bone formation. Increased bone turnover results in a disorganised mosaic of woven and lamellar bone at affected skeletal sites. This produces bone that is expanded in size, less compact, more vascular, and more susceptible to deformity or fracture than normal bone. Symptoms of Paget's disease may include bone pain, bone deformity, excessive warmth over bone from hypervascularity, secondary arthritis, and a variety of neurologic complications caused in most instances by compression of the neural tissues adjacent to pagetic bone. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis remains largely unknown. The identification of the molecular basis of Paget's disease is fundamental for an understanding of the cause of the disease, for identifying subjects at risk at a preclinical stage, and for the development of more effective preventive and therapeutic strategies for the management of the condition. With this in mind, the aim of this project is to identify genetic loci, in a large pedigree, that may harbour genes responsible for Paget's disease of bone. A large Australian family with evidence of Paget's disease was recruited for these studies (Chapter 3). This pedigree has characterised over 250 individuals, with 49 informative individuals affected with Paget's disease of bone, 31 of whom are available for genotypic analysis. The pattern of disease in these individuals is polystotic, with sites of involvement including the spine, pelvis, skull and femur. Although the affected individuals have a severe early-onset form of the disease, the clinical features of the pedigree suggest that the affected family members have Paget's disease and not familial expansile osteolysis (a disease with some similarities to Paget's disease), as our patients have extensive skull and axial skeletal involvement. The disease is inherited as an autosomal dominant trait in the pedigree with high penetrance by the sixth decade. Due to the large size of this family and multiple affected members, this pedigree is a unique resource for the detection of the susceptibility gene in Paget's disease. The first susceptibility loci for Paget's disease of bone have been mapped by other investigators to chromosome 6p21 (PDB1) and 18q21.1-q22 (PDB2) in different pedigrees. Linkage analysis of the Australian pedigree in these studies was performed with markers at PDB1: these data showed significant exclusion of linkage, with LOD scores < - 2 in this region (Chapter 4). Linkage analysis of microsatellite markers from the PDB2 region excluded linkage with this region also, with a 30 cM exclusion region (LOD score < -2.0) centred on D18S42 (Chapter 4). This locus on chromosome 18q21.1-q22 contains a serine protease (serpin) cluster with similarities to chromosome 6p21. Linkage analysis of this region also failed to provide evidence of linkage to this locus (Chapter 4). These data are consistent with genetic heterogeneity of Paget's disease of bone. A gene essential for osteoclast formation encoding receptor activator of nuclear factor-kB (RANK), TNFRSF11A, has been previously mapped to the PDB2 region. Mutations in the TNFRSF11A gene have been identified segregating in pedigrees with Familial Expansile Osteolysis and early onset familial Paget's disease, however, linkage studies and mutation screening have excluded the involvement of RANK in the majority of Paget's disease patients. For the Australian pedigree, mutation screening at the TNFRSF11A locus revealed no mutations segregating with affected individuals with Paget's disease (Chapter 4). Based on these findings, our hypothesis is that a novel susceptibility gene relevant to the pathogenesis of Paget's disease of bone lies elsewhere in the genome in the affected members of this pedigree; this gene should be identifiable using a microsatellite genome-wide scan followed by positional cloning. A genome-wide scan of the Australian pedigree was carried out, followed by fine mapping and multipoint analysis in regions of interest (Chapter 5). The peak 2-point LOD scores from the genome-wide scan were LOD = 2.75 at D7S507 and LOD = 1.76 at D18S70. Two additional regions were also considered for fine mapping: chromosome 19p11-q13.1 with a LOD of 1.58 and chromosome 5q35-qter with a LOD of 1.57. Multipoint and haplotype analysis of markers flanking D7S507 did not support linkage to this region (Chapter 5). Similarly, fine mapping of chromosome 19p11-q13.1 failed to support linkage to this region (Chapter 5). Linkage analysis with additional markers in the region on chromosome 5q35-qter revealed a peak multipoint LOD score of 6.77 (Chapter 5). A distinct haplotype was shown to segregate with all members of the family, except the offspring of III-5 and III-6. Haplotype analysis of markers flanking D18S70 demonstrated a haplotype segregating with Paget's disease in a large sub-pedigree (descendants of III-3 and III-4) (Chapter 5). This sub-pedigree had a significantly lower age at diagnosis than the rest of the pedigree (51.2 + 8.5 vs. 64.2 + 9.7 years, p = 0.0012). Linkage analysis of this sub-pedigree demonstrated a peak two-point LOD score of 4.23 at marker D18S1390 (q = 0.00), and a peak multipoint LOD score of 4.71, at marker D18S70. An implication of these data is that 18q23 harbours a novel modifier gene for reducing the age of onset of Paget's disease of bone. A number of candidate Paget's genes have previously been identified on chromosome 18q23, including the nuclear factor of activated T cells (NFATc1), membrane-associated guanylated kinase (MAGUK) and a zinc finger protein. Candidate gene sequencing of these genes in these studies has failed to identify mutations segregating with affected family members in the sub-pedigree linked to chromosome 18q23 (Chapter 6). More recently, a mutation in the gene encoding the ubiquitin-binding protein sequestosome 1 (SQSTM/p62) has been shown to segregate with affected members of Paget's disease families of French-Canadian origin. In this study, a single base pair deletion (1215delC) was identified as segregating with the majority of affected members in the pedigree (Chapter 6). This deletion introduces a stop codon at amino acid position 392 which potentially results in early termination of the protein and loss of the ubiquitin binding domain. The three affected members of the family that do not share the affected haplotype do not carry a mutation in the coding region of SQSTM/p62. Screening of affected members from 10 further Paget's disease families identified the previously reported P392L mutation in 2 (20%) families. No SQSTM1/p62 coding mutations have been found in the remaining 8 families or in 113 aged matched controls. In conclusion, this project has identified genetic loci and mutations that segregate with individuals affected with Paget's disease. Further investigation of the functional significance of the genetic changes at these loci is expected to lead to a better understanding of the molecular basis of this disease.

Mutations affecting the p62 signalling adapter protein are commonly found in patients with the skeletal disorder Paget‟s disease of bone (PDB). We have extended previous in vitro functional analyses of PDB-mutant p62 proteins (Cavey et al., 2006) to study the effects of several uncharacterised PDB-associated mutations on the ubiquitin-binding properties of p62. These include mutations which affect regions of p62 outside of the ubiquitin-binding UBA domain (A381V, D335E and a mutant equivalent to a predicted product of the G1205C splice-site mutation which lacks amino acids 351-388), as well as a double mutation involving the P392L and S399P changes on the same allele. In accordance with previous findings, both of the non-UBA domain mutations (A381V, ∆351-388) showed deleterious effects on ubiquitin-binding by p62 in pull-down assays, further emphasising the important role of non-UBA domain sequences in mediating ubiquitin-recognition, as well as in PDB aetiology. The D335E mutant retained its ubiquitin-binding function in vitro. The P392L/S399P double mutant showed a more severe effect on ubiquitin-binding than either of the single P392L or S399P missense mutations alone; as this double mutation is associated with a particularly severe phenotype, our findings are supportive of the proposal that disease severity in PDB with p62 mutations may be directly related to the effects of the mutations on the ubiquitin-binding function of the p62 protein. Since the in vitro pull-down assays are semi-quantitative at best, we sought to investigate if a more quantitative biophysical approach, two dimensional Heteronuclear Single Quantum Coherence (2D-HSQC) protein NMR, might be applied to investigate the effects of PDB-associated mutations on protein (ubiquitin-binding) function. Our results showed that protein NMR was not optimal to quantitatively assess the effects of the mutations on the interaction between p62 and ubiquitin in vitro. Using confocal microscopy, co-transfection of U20S cells showed that the selected PDB-associated p62 mutants (A381V, P392L, G425R) co-localised with ubiquitin with a cellular phenotype indistinguishable from wild type, as each PDB mutant formed cytoplasmic bodies with an area ranging from the detection limit of the microscope to 40μm2 or higher; in contrast the E396X truncating mutant did not form cytoplasmic bodies nor co-localise with ubiquitin. In addition to interacting with ubiquitin, p62 also interacts with the LC3 (an autophagic marker) through its LC3 interacting region (LIR) to mediate the formation of autophagosomes. By co-transfecting p62 constructs with LC3 We found that some of the p62-positive cytoplasmic bodies were autophagosomes, and that the D335E mutation of p62 (which lies within the LIR) did not appear to affect the formation of autophagosomes. The effects of the wild type and PDB-mutant p62 proteins on NF-κB signalling were assessed in HEK293 cells co-transfected with an NF-κB luciferase reporter construct. A381V mutant p62 produced a level of activation of NF-κB signalling greater than wildtype and similar to that of UBA domain mutants, indicating that non-UBA and UBA domain mutations may exert their effects through a common mechanism involving dysregulated NF-κB signalling. To further examine the function of p62 in the regulation of NF-κB signalling, we went on to determine possible effects of PDB-associated mutations on p62-CYLD (a DUB enzyme) interactions. Unexpectedly we found that CYLD expression appears to abrogate the formation of the p62 cytoplasmic bodies previously shown to be ubiquitin-positive. Finally, we went on to study the interaction of p62 (and its PDB mutants) with another important regulator of NF-κB signalling, IKKγ/NEMO. We concluded that wild type and PDB-mutant p62 proteins are capable of recruiting NEMO to cytoplasmic bodies which may represent autophagosomes, but do not appear to accelerate its degradation.

Paget's disease of the bone is a skeletal disorder of unknown cause. This disease is characterised by excessive and abnormal bone remodelling brought about by increased bone resorption followed by disorganised bone formation. Increased bone turnover results in a disorganised mosaic of woven and lamellar bone at affected skeletal sites. This produces bone that is expanded in size, less compact, more vascular, and more susceptible to deformity or fracture than normal bone. Symptoms of Paget's disease may include bone pain, bone deformity, excessive warmth over bone from hypervascularity, secondary arthritis, and a variety of neurologic complications caused in most instances by compression of the neural tissues adjacent to pagetic bone. Genetic factors play a role in the pathogenesis of Paget's disease but the molecular basis remains largely unknown. The identification of the molecular basis of Paget's disease is fundamental for an understanding of the cause of the disease, for identifying subjects at risk at a preclinical stage, and for the development of more effective preventive and therapeutic strategies for the management of the condition. With this in mind, the aim of this project is to identify genetic loci, in a large pedigree, that may harbour genes responsible for Paget's disease of bone. A large Australian family with evidence of Paget's disease was recruited for these studies (Chapter 3). This pedigree has characterised over 250 individuals, with 49 informative individuals affected with Paget's disease of bone, 31 of whom are available for genotypic analysis. The pattern of disease in these individuals is polystotic, with sites of involvement including the spine, pelvis, skull and femur. Although the affected individuals have a severe early-onset form of the disease, the clinical features of the pedigree suggest that the affected family members have Paget's disease and not familial expansile osteolysis (a disease with some similarities to Paget's disease), as our patients have extensive skull and axial skeletal involvement. The disease is inherited as an autosomal dominant trait in the pedigree with high penetrance by the sixth decade. Due to the large size of this family and multiple affected members, this pedigree is a unique resource for the detection of the susceptibility gene in Paget's disease. The first susceptibility loci for Paget's disease of bone have been mapped by other investigators to chromosome 6p21 (PDB1) and 18q21.1-q22 (PDB2) in different pedigrees. Linkage analysis of the Australian pedigree in these studies was performed with markers at PDB1: these data showed significant exclusion of linkage, with LOD scores < - 2 in this region (Chapter 4). Linkage analysis of microsatellite markers from the PDB2 region excluded linkage with this region also, with a 30 cM exclusion region (LOD score < -2.0) centred on D18S42 (Chapter 4). This locus on chromosome 18q21.1-q22 contains a serine protease (serpin) cluster with similarities to chromosome 6p21. Linkage analysis of this region also failed to provide evidence of linkage to this locus (Chapter 4). These data are consistent with genetic heterogeneity of Paget's disease of bone. A gene essential for osteoclast formation encoding receptor activator of nuclear factor-kB (RANK), TNFRSF11A, has been previously mapped to the PDB2 region. Mutations in the TNFRSF11A gene have been identified segregating in pedigrees with Familial Expansile Osteolysis and early onset familial Paget's disease, however, linkage studies and mutation screening have excluded the involvement of RANK in the majority of Paget's disease patients. For the Australian pedigree, mutation screening at the TNFRSF11A locus revealed no mutations segregating with affected individuals with Paget's disease (Chapter 4). Based on these findings, our hypothesis is that a novel susceptibility gene relevant to the pathogenesis of Paget's disease of bone lies elsewhere in the genome in the affected members of this pedigree; this gene should be identifiable using a microsatellite genome-wide scan followed by positional cloning. A genome-wide scan of the Australian pedigree was carried out, followed by fine mapping and multipoint analysis in regions of interest (Chapter 5). The peak 2-point LOD scores from the genome-wide scan were LOD = 2.75 at D7S507 and LOD = 1.76 at D18S70. Two additional regions were also considered for fine mapping: chromosome 19p11-q13.1 with a LOD of 1.58 and chromosome 5q35-qter with a LOD of 1.57. Multipoint and haplotype analysis of markers flanking D7S507 did not support linkage to this region (Chapter 5). Similarly, fine mapping of chromosome 19p11-q13.1 failed to support linkage to this region (Chapter 5). Linkage analysis with additional markers in the region on chromosome 5q35-qter revealed a peak multipoint LOD score of 6.77 (Chapter 5). A distinct haplotype was shown to segregate with all members of the family, except the offspring of III-5 and III-6. Haplotype analysis of markers flanking D18S70 demonstrated a haplotype segregating with Paget's disease in a large sub-pedigree (descendants of III-3 and III-4) (Chapter 5). This sub-pedigree had a significantly lower age at diagnosis than the rest of the pedigree (51.2 + 8.5 vs. 64.2 + 9.7 years, p = 0.0012). Linkage analysis of this sub-pedigree demonstrated a peak two-point LOD score of 4.23 at marker D18S1390 (q = 0.00), and a peak multipoint LOD score of 4.71, at marker D18S70. An implication of these data is that 18q23 harbours a novel modifier gene for reducing the age of onset of Paget's disease of bone. A number of candidate Paget's genes have previously been identified on chromosome 18q23, including the nuclear factor of activated T cells (NFATc1), membrane-associated guanylated kinase (MAGUK) and a zinc finger protein. Candidate gene sequencing of these genes in these studies has failed to identify mutations segregating with affected family members in the sub-pedigree linked to chromosome 18q23 (Chapter 6). More recently, a mutation in the gene encoding the ubiquitin-binding protein sequestosome 1 (SQSTM/p62) has been shown to segregate with affected members of Paget's disease families of French-Canadian origin. In this study, a single base pair deletion (1215delC) was identified as segregating with the majority of affected members in the pedigree (Chapter 6). This deletion introduces a stop codon at amino acid position 392 which potentially results in early termination of the protein and loss of the ubiquitin binding domain. The three affected members of the family that do not share the affected haplotype do not carry a mutation in the coding region of SQSTM/p62. Screening of affected members from 10 further Paget's disease families identified the previously reported P392L mutation in 2 (20%) families. No SQSTM1/p62 coding mutations have been found in the remaining 8 families or in 113 aged matched controls. In conclusion, this project has identified genetic loci and mutations that segregate with individuals affected with Paget's disease. Further investigation of the functional significance of the genetic changes at these loci is expected to lead to a better understanding of the molecular basis of this disease.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
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La maladie osseuse de Paget (MP) est une maladie métabolique de l’os. Bien que les facteurs génétiques jouent un rôle important dans la pathogénie de la MP, les facteurs environnementaux tels que la résidence rurale et l’exposition au chauffage au bois ont été associés avec la MP. Afin d’étudier le rôle des polluants de l'air extérieur et intérieur sur la MP, nous avons administré un questionnaire chez 140 patients canadiens-français avec la MP et 113 témoins sains. Ce questionnaire portait sur la pollution de l'air extérieur, comme la résidence près d'une autoroute, d’une station de bus, de train ou d’un aéroport, d’une station d'essence, et sur les polluants de l'air intérieur en mettant l'accent sur les combustibles de chauffage (charbon, bois, huile) et l'exposition au tabac. Dans un sous-groupe de patients, la concentration urinaire de 17 métaux lourds et de 11 hydrocarbures aromatiques polycycliques a été mesurée par spectrométrie de masse. À la lumière de ce que nous savions dès le questionnaire et les dosages urinaires, nous avons identifié certains toxiques pouvant être des facteurs de risque pour la MP. Pour explorer les effets in vitro de ces toxiques sur les ostéoclastes dans la MP, nous avons réalisé une différentiation in vitro de monocytes du sang périphérique provenant de plus de 40 participants, patients, porteurs sains de mutation dans le gène SQSTM1, et des témoins sains, en ostéoclastes traités avec ou sans les toxiques identifiés. La morphologie des ostéoclastes, le pourcentage de résorption osseuse, les niveaux d'expression génique, et les niveaux de stress oxydatif cellulaire ont été analysés. Les résultats ont montré un effet inhibiteur du condensé de la fumée de cigarette et des métaux lourds sur la morphologie et la fonction des ostéoclastes. De plus, des taux élevés de stress oxydatif chez les ostéoclastes des patients ont été observés, et un profil hétérogène des effets de métaux lourds sur l'expression des gènes a été identifié.
Paget's disease of bone (PDB) is a metabolic bone disease. Although genetic factors play an important role in the pathogenesis of PDB, environmental factors such as rural residence and the exposure to wood heating was associated with PDB. In order to study the role of outdoor and indoor air pollutants on PDB, we performed a survey in 140 French-Canadian patients with PDB and 113 healthy controls. The survey covered the outdoor air pollution such as the residence near a highway, a bus station, a train or an airport or a gas station, and indoor air pollutants by focusing on heating fuels (carbon, wood, oil) and exposure to tobacco smoke. In a subgroup of patients, urinary concentration of 17 heavy metals and 11 polycyclic aromatic hydrocarbons was measured by mass spectrometry. In light of what we knew from the survey and urinary assays, we identified certain toxics that could be risk factors for PDB. To explore the in vitro effects of these toxics on osteoclasts in PDB, we conducted in vitro monocytes differentiation from peripheral blood of more than 40 participants, patients, healthy carriers of p.Pro392Leu mutation, and healthy controls, which osteoclasts were treated with or without the identified toxic. The morphology of osteoclasts, the percentage of bone resorption, gene expression level, and cellular oxidative stress levels were assayed. The results showed an inhibitory effect of cigarette smoke condensate and heavy metals on morphology and function of patients’ osteoclasts. Further, high levels of oxidative stress in patients’ osteoclasts were observed, and a heterogenic profile of heavy metals effect on gene expression was identified.

Genetic factors play an important role in the pathogenesis of Paget’s Disease of Bone (PDB). The most important predisposing gene is SQSTM1 which is mutated in about 10% of patients, additionally common variants at seven other loci have also been shown to predispose to PDB as well as environmental factors which are also important in the pathogenesis of PDB. Little research has been conducted on the relationship between the genetic variants that predispose to PDB and disease severity. Similarly, only limited information exists on the role that gene-environment interactions play in the pathogenesis of PDB or its severity. The aim of the present thesis was to explore these issues in participants of the Paget’s Disease Randomised Trial of Intensive versus Symptomatic Management study (PRISM) and other study cohorts. In chapter 3, I investigate the relationship between SQSTM1 mutation status, disease severity and clinical outcome in 737 patients from the PRISM study. Mutations of SQSTM1 were detected in 80/737 (10.9%) patients. Mutation carriers had an earlier age at diagnosis; a greater number of affected bones and more commonly had required orthopaedic surgery and bisphosphonate therapy than those without mutations. Quality of life was significantly reduced in carriers and during the study; fractures were more common although most of these occurred in unaffected bone. This study demonstrates that SQSTM1 mutations are strongly associated with disease severity and complications of PDB. In chapter 4, I study associations between common genetic variants identified by genome wide association (GWAS), clinical severity and extent of PDB, alone and in combination with SQSTM1 mutations. This showed that these common variants were also associated with severity and extent of PDB in PRISM, but with weaker effects than SQSTM1 mutations. The findings were replicated in a multinational study involving 1940 subjects from centres in Italy, Spain and Australia. In all cohorts the GWAS risk alleles acted in an additive manner with SQSTM1 mutations to regulate disease severity and extent. By combining information from SQSTM1 status and the new risk alleles, however, we are able to develop a genetic risk score which delineated three distinct groups with markedly differing effects on disease extent and severity. In chapter 5, I study associations between PDB, severity and extent in relation to circulating levels of IgG antibodies against various viruses including Rubella, respiratory syncytial virus, distemper, varicella zoster virus, measles and mumps. We found little evidence of an interaction between viral antibody titres and SQSTM1 in predicting disease severity with the notable exception of mumps virus where subjects with the highest levels of antibodies that were SQSTM1 positive had in increased age at diagnosis than the other genotype / viral antibody groups. Overall the studies do provide no support for the notion that patients with PDB have an abnormal antibody response to paramyxovirus or have had previous infections with these viruses more frequently than controls. This of course does not exclude the possibility that PDB patients might have a clinically occult slow virus infection which is not accompanied by an abnormality in the immune response. . This raises the possibility that genetic testing may be of value in identifying individuals at risk of developing severe disease and those at risk of complications. I also demonstrate that PBD patients have abnormalities in circulating antibodies to various viruses suggesting that the disease may be associated with disturbance in the response of the immune system to infectious agents but further investigation is required. This, perhaps, could explain the changes in the severity and prevalence of PDB that have been observed over recent years in several countries.

Paget’s disease of bone (PDB) is a common disease with a strong genetic component. Approaches such as linkage analysis and candidate gene studies have shown that mutations in Sequestosome 1 (SQSTM1) explain up to 40% of familial cases and 10% of sporadic cases, however the majority of PDB patients have no mutations in this gene. Genome-wide association studies (GWAS) have recently identified new susceptibility loci for PDB including variants at CSF1, TNFRSF11A, OPTN, TM7SF4, PML, NUP205 and RIN3 loci. These loci were confirmed to be associated with PDB in various European populations. OPTN encodes optineurin, a widely expressed protein involved in many cellular processes but its role in bone metabolism is yet unknown. The aim of this PhD thesis was to investigate the role of OPTN in bone metabolism and PDB using in vitro and in vivo studies. In chapter 3, the OPTN rs1561570 identified by previous GWAS was examined for its association with the severity and clinical outcome of PDB in patients without SQSTM1 mutations. The results showed that rs1561570 was significantly associated with total disease severity score so that carriers of the risk allele “T” had higher severity score compared to non-carriers (P < 0.05). A trend for reduced quality of life physical scores (SF36) was also associated with the rs1561570 risk allele, but the relationship was not statistically significant. In order to identify functional variants within OPTN, the coding regions as well as the exon-intron boundaries were sequenced in 24 familial PDB cases and 19 controls. No mutation was found that could be predicted as pathogenic suggesting that disease susceptibility could be mediated by regulatory polymorphisms that influence gene expression. In chapter 4, the role of OPTN was investigated in osteoclast development using in vitro knockdown experiments. Optn was expressed in mouse bone marrow derived macrophages (BMDMs) as well as all stages of osteoclast development and it was significantly increased three days post RANKL treatment. Optn expression was knocked down in BMDMs and cells were induced to form osteoclast in the presence of RANKL and M-CSF. Compared to non-targeted cells, Optn depleted cells formed significantly more and larger osteoclasts (P< 0.05). Optn knockdown was also found to enhance osteoclast survival as well as RANKL-induced NFκB activation. In chapter 5, the role of OPTN was investigated in vitro from cells obtained from knock in mice with a loss-of-function mutation in Optn (OptnD477N/D477N). In agreement with the in vitro knockdown experiments, osteoclasts were significantly higher and larger in mutant mice compared to WT and the NF-B activity measured by luciferase reporter assay was significantly higher in cells from OptnD477N/D477N compared to WT during most stages of osteoclast development. OPTN from mutant and WT mice was co-precipitated with its CYLD binding-partner, which acts as a negative regulator to RANK signalling by inhibiting the TRAF6 downstream signalling. The data from this immunoprecipitation (IP) experiment revealed that defective OPTN interacted less with CYLD from mutant mice compared to WT. This study also showed that OPTN was expressed in osteoblasts and the expression rate did not change during osteoblast development. The data obtained from the mineralization assay revealed no significant difference between OptnD477N/D477N and WT. In chapter 6, I investigated the effect of the D477N loss of function mutation in Optn on bone metabolism. Bone Histomorphometrical analysis of OptnD477N/D477N mice showed higher bone resorption parameters (Oc.N/BS and Oc.S/BS) compared to wild type (WT). Osteoid analysis showed evidence of increased bone formation parameters (OS/BS and OV/BV) in mutant mice compared to WT. Calcein labelling showed a significant difference in mineral apposition rate (MAR) from mutant mice compared to WT. Analysis of serum biomarkers of bone turnover showed evidence of enhanced bone turnover in mutant mice compared to WT. Micro computed tomography (μCT) analysis of 4 and 14 months old mice showed no significant differences in bone morphology between WT and OptnD477N/D477N mice of both sexes. In conclusion, this study has shown for the first time that OPTN plays a role in regulating bone turnover by acting as a negative regulator of osteoclast differentiation. The data obtained from this study strongly suggest the crucial role of OPTN in RANK signalling. The effect of OPTN on osteoblast activity may be direct or indirect compensation for increased osteoclast activity. Further detailed studies will be required to explore the underlying mechanism of OPTN including downstream RANK signalling and a complete knockout model to corroborate these findings.

Paget’s Disease of Bone (PDB) is a common condition characterised by focally increased bone turnover, which is believed to be caused by an aberrant osteoclast. Genetic factors are important in the pathogenesis of PDB and mutations in the TNFRSF11B encoding osteoprotegerin (OPG) and Sequestosome 1 (SQSTM1 ) encoding SQSTM1 or p62 cause juvenile and classic PDB of late onset respectively. OPG and p62 play an important role in the RANK-NFκB signalling pathway, key for normal osteoclastogenesis. I have shown that the TNFRSF11B G1181C polymorphism causing a lysine to asparagine change in the 3^rd codon of the OPG signal peptide (SP-OPG) predisposes to PDB. Heterozygous cases for G1181C are prone to severe disease as opposed to homozygous cases (a positive heterosis effect). There is a difference in cellular localisation of respective SP-OPG variants and a degree of cellular accumulation of the SP-OPG variant containing lysine in the 3^rd codon, suggesting that the latter may be inefficiently secreted at times of high demand at a local level, which could lead to increased bone resorption. Studies of p62 revealed a novel interaction between p62 and P-IκB-α and between p62 and VCP. PDB-causing mutations of the p62 UBA domain interfered with the interaction between p62 and P-IκB-α, but not between p62 and VCP, shedding a new light on the mechanism underlying the pathogenesis of PDB. Accumulation of IκB-α in the presence of the PDB-causing mutations of p62 was present, suggesting that p62 may regulate IκB-α degradation. Implications of these findings are discussed. This work provides novel insights into the molecular mechanisms underlying PDB and the findings are expected to become the groundwork for further studies trying to unravel the complexity of the pathogenesis of Paget’s disease of bone.

Excluding monogenic bone disorders, it is now well established that in complex multifactorial diseases, with a recognized hereditary component, such as Paget’s disease of bone and osteoporosis, the associated genetic variants have a limited impact on gene expression and explain only a small fraction of the disease risk. Moreover, a larger proportion of variants associated to many human traits or diseases fall in loci which do not encode proteins, suggesting that additional mechanisms other than gene-gene and gene-environment interactions might be involved. In this setting, we focus our attention on Paget’s disease of bone, osteoporosis, and hyperparathyroidism to clarify epigenetic mechanisms involved in their pathogenesis. MicroRNAs (miRNAs) are small (∼22 nt), noncoding single-stranded RNAs that have emerged as important posttranscriptional regulators of gene expression, with an essential role in vertebrate development and several biological processes. They contribute to every step of osteogenesis and bone homeostasis, from embryonic skeletal development to maintenance of adult bone tissue, by regulating the growth, differentiation, and activity of different cell systems inside and outside the skeleton. However, despite the rising number of experimental reports about this issue, our understanding of the exact mechanisms through which miRNAs are involved in the pathogenesis of Paget’s disease of bone, osteoporosis, and hyperparathyroidism remain unclear. For these reasons, we performed a miRNAs expression profiling in peripheric mononuclear cells (PBMCs) and serum of wild type pagetic patients (PDB-WT) and with mutations on the SQSTM1 gene (PDB-MUT) and osteoporotic subjects (OP) compared to healthy controls, using TaqMan Low Density MicroRNA Array Cards. After that, we performed the same analysis in serum of patients with hypercalcemic primary hyperparathyroidism and osteoporosis (H-PHPT) and normocalcemic primary hyperparathyroidism without osteoporosis (N-PHPT), compared to healthy controls. Differentially expressed miRNAs identified in PBMCs of pagetic and osteoporotic patients were then validated in single assay, while the validation of miRNAs identified in the serum of all subjects is ongoing. A bioinformatic analysis (Gene Ontology analysis) was performed to find putative functional pathways and biological processes linked to some differentially expressed miRNAs. These analyses identified numerous genes and pathways involved in regulation of osteoclasts, osteoblasts differentiation and bone metabolism in all the three pathologies considered. These results could be used not only to better understand new molecular mechanisms involved in Paget’s disease, osteoporosis, and hyperparathyroidism pathogenesis, but also as a resource of new biomarkers that could be introduced in the clinical practice as diagnostic tools.

Paget's disease of bone (PDB) is characterised by focal lesions of increased bone turnover driven by overactive osteoclasts, which often contain nuclear and cytoplasmic inclusion bodies. Mutations affecting the sequestosome-1 (SQSTM1) ubiquitin-associated (UBA) domain have been identified in individuals with PDB. SQSTM1, also known as p62, is a ubiquitously expressed multidomain scaffold protein of 62 kDa that functions in multiple signalling pathways important for cell survival and osteoclast activity. The mechanisms by which SQSTM1 mutations cause PDB remain unclear. Using immunohistochemistry, I showed evidence that protein degradation pathway components, both from the UPS and the autophagy pathway, are elevated in osteoclasts in patients with PDB compared with control osteoclasts from patients without PDB. Using molecular and microscopical methods to examine Pagetic bone biopsies, osteoclast cultures and various cell lines, I have identified two isoforms of SQSTM1. In all cell types examined, four SQSTM1 transcripts were detected, differing in their 5′-untranslated region; one transcript encodes p62, while the other three encode a 55 kDa isoform of SQSTM1. The newly identified isoform also contains the UBA domain mutated in PDB. Using biochemical and microscopical methods, I found that both SQSTM1 isoforms are degraded by autophagy. The isoforms interact with each other and form aggregates upon autophagy inhibition. SQSTM1-55 is ~21× more abundant in osteoclasts than SQSTM1/p62. Biochemical and microscopical methods showed that PDB-causing mutations in SQSTM1/p62 impair its autophagic degradation. Cell lines expressing SQSTM1/p62 mutations form paracrystalline inclusion bodies that by immuno-transmission electron microscopy (TEM) were found to contain SQSTM1 and ubiquitin and were ultrastructurally identical to those found in PDB. As observed by TEM, these inclusions can be degraded by autophagy. The effects of mutations in SQSTM1-55 have yet to be characterised. Abstract Taken together, these data show that mutations in SQSTM1 isoforms impair protein degradation and can lead to inclusion body formation suggesting that PDB results from dysregulated protein degradation in osteoclasts.

Paget’s disease of bone (PDB) shows a strong genetic component and mutations in SQSTM1 (Sequestosome 1) are observed in about 10% of sporadic PDB patients. My PhD investigated the RIN3 gene (Ras and Rab interactor protein 3), previously implicated in the pathogenesis of PDB by GWAS. The RIN3 gene encodes a guanine exchange factor (GEF), involved in the activation of GTPases which are crucial in osteoclast activity. It also has a role in endocytosis and recycling of tyrosine kinase receptor. The role of RIN3 in bone remodelling is unclear, however some investigations revealed some associations with bone: RIN3 has been associated with high lower limb bone mineral density in children in a meta-analysis of GWAS studies, and was shown to be expressed in primary calvarial osteoblasts. The expression of RIN3 was down regulated during human primary osteoclast differentiation, and also in iliac bone biopsies from osteoporotic patients compared to healthy postmenopausal donors (Kemp et al, 2014).   In Chapter 1, I present normal bone structure, composition and remodelling before detailing PDB and its genetics. I then introduce RIN3 as a candidate gene for PDB. In Chapter 2, I describe all methods performed and materials used for the completion of this project. This includes primary cell cultures, RNA and protein work, immunostaining, immunochemistry and phenotype analysis on Rin3-/- mice. Chapter 3 presents the fine mapping of RIN3 using Sanger and next generation sequencing performed on PDB cases and controls. 18 variants were detected and one common variant (p.R279C) showed a strong association with PDB. Rare variants were also over-represented in cases, and many were shown to be on the same haplotype as p.R279C. Chapter 4 details the association study performed on a UK cohort and includes the investigation of the clinical phenotype severity in patients against the RIN3 mutations. Chapter 5 presents the expression pattern of RIN3 in bone cells and bone microenvironment. Important variations of RIN3 mRNA and protein were detected during the differentiation of bone marrow derived osteoclasts. Protein levels of RIN3 were also found in osteoclasts from human osteoclastoma, human osteosarcoma, PDB patients, giant cell tumour (GCT) and healthy controls. Within all the mouse tissues analysed, Rin3 mRNA was expressed the highest in bone after lung. Chapter 6 focuses on the work performed on mice deficient of the Rin3 gene. They showed a higher trabecular bone volume and a smaller active resorption surface occupied by osteoclasts in trabecular bone. In conclusion, the combined in vitro and in vivo analyses have uncovered that RIN3 plays a role in bone metabolism and is a strong gene candidate for PDB.

The microstructural impact of diagenetic or post mortem alteration has been assessed in predominately human skeletal tissues. The method of assessment selected was microscopical analysis, mainly using backscattered electron imaging in a scanning electron microscope and, to a lesser extent, confocal reflection microscopy. The microstructural morphologies of post mortem alteration were investigated in archaeological material, both normal and pathological, from terrestrial and marine contexts. Further studies were undertaken on a case-by-case basis on skeletal material which offered some unique pathology, environmental context, spatial relationship, time variable, or mortuary practice. Additionally, the effect of diagenetic change on mitochondrial DNA (mtDNA) recovery and the potential location of DNA within the skeletal tissues were investigated. Two quantitative studies were undertaken to validate and measure the observed mineral density changes. The investigations showed that post mortem alteration or diagenetic change to skeletal material can be extensive, and can occur shortly after death. Diagenesis did not represent a post burial phenomenon as the term diagenesis suggests, but was found to have begun above ground in a range of exposural contexts. The implication of gut bacteria in the promotion of early bacterially-related microstructural change was strong, and it is proposed that body status at the point of, or soon after, death is important. Post mortem alteration to skeletal microstucture can provide environmental information, since terrestrial and marine contexts exhibited distinct morphologies. It may also provide localized environmental information within a stratigraphic matrix. Characterizing the post mortem microstructural and density changes to bone has helped to elucidate the preservational status of mtDNA in terms of its relative retrieval in archaeological specimens, and the potential location of mtDNA in bone. It is proposed that the shift in mineral density that was found in bacterially-remodelled specimens from terrestrial contexts, relative to the excellent preservation of marine specimens, may help to explain why marine vertebrates far outnumber terrestrial ones in the fossil record, since bacterially driven microstructural change is here considered to be a destructive form of fossilisation.

Résumé : La maladie osseuse de Paget (MP) est un désordre squelettique caractérisé par une augmentation focale et désorganisée du remodelage osseux. Les ostéoclastes (OCs) de MP sont plus larges, actifs et nombreux, en plus d’être résistants à l’apoptose. Même si la cause précise de la MP demeure inconnue, des mutations du gène SQSTM1, codant pour la protéine p62, ont été décrites dans une proportion importante de patients avec MP. Parmi ces mutations, la substitution P392L est la plus fréquente, et la surexpression de p62P392L dans les OCs génère un phénotype pagétique partiel. La protéine p62 est impliquée dans de multiples processus, allant du contrôle de la signalisation NF-κB à l’autophagie. Dans les OCs humains, un complexe multiprotéique composé de p62 et des kinases PKCζ et PDK1 est formé en réponse à une stimulation par Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL), principale cytokine impliquée dans la formation et l'activation des OCs. Nous avons démontré que PKCζ est impliquée dans l’activation de NF-κB induite par RANKL dans les OCs, et dans son activation constitutive en présence de p62P392L. Nous avons également observé une augmentation de phosphorylation de Ser536 de p65 par PKCζ, qui est indépendante d’IκB et qui pourrait représenter une voie alternative d'activation de NF-κB en présence de la mutation de p62. Nous avons démontré que les niveaux de phosphorylation des régulateurs de survie ERK et Akt sont augmentés dans les OCs MP, et réduits suite à l'inhibition de PDK1. La phosphorylation des substrats de mTOR, 4EBP1 et la protéine régulatrice Raptor, a été évaluée, et une augmentation des deux a été observée dans les OCs pagétiques, et est régulée par l'inhibition de PDK1. Également, l'augmentation des niveaux de base de LC3II (associée aux structures autophagiques) observée dans les OCs pagétiques a été associée à un défaut de dégradation des autophagosomes, indépendante de la mutation p62P392L. Il existe aussi une réduction de sensibilité à l’induction de l'autophagie dépendante de PDK1. De plus, l’inhibition de PDK1 induit l’apoptose autant dans les OCs contrôles que pagétiques, et mène à une réduction significative de la résorption osseuse. La signalisation PDK1/Akt pourrait donc représenter un point de contrôle important dans l’activation des OCs pagétiques. Ces résultats démontrent l’importance de plusieurs kinases associées à p62 dans la sur-activation des OCs pagétiques, dont la signalisation converge vers une augmentation de leur survie et de leur fonction de résorption, et affecte également le processus autophagique.
Abstract : Paget’s disease of bone (PDB) is a skeletal disorder characterized by focal and disorganized increases in bone turnover. In PDB, osteoclasts are larger, more active, more numerous, and resistant to apoptotic stimuli. While no single root cause has been identified, mutations to the gene encoding the p62 protein, SQSTM1, have been described in a significant population of patients with PDB. Among these mutations, the P392L substitution is the most prevalent, and overexpression of p62P392L in osteoclasts generates at least a partial pagetic phenotype in vitro. Normally this protein mediates a number of cell functions, from control of NF-κB signaling to autophagy. In human osteoclasts, a multiprotein complex containing p62 and protein kinases PKCζ and PDK1 (the principal kinase of Akt), form in response to stimulation by receptor activator of nuclear factor kappa-B ligand (RANKL), the principal osteoclastogenic-signaling cytokine. We found that PKCζ is involved in RANKL-induced activation of NF-κB, and that it contributed to a basal activation of NF-κB observed in p62P392L mutants. This may be regulated in part by a PKCζ dependent increase in p65 phosphorylation at Ser536 which we characterized, independent of IκB. This could represent one alternative pathway by which mutant p62 leads to increased NF-κB activation. We observed increased basal phosphorylation of survival regulators ERK and Akt in PDB that was reduced upon PDK1 inhibition. The activity of 4EBP1 and Raptor, associated with mTOR activity, were also altered in pagetic osteoclasts and regulated by PDK1 inhibition. We then identified autophagic defects common to pagetic osteoclasts; with higher basal levels of LC3II (associated with autophagic structures), regardless of p62 mutation, and reduced sensitivity to autophagy induction in PDB. These results suggest an accumulation of non-degradative autophagosomes. Inhibition of PDK1 not only induced apoptosis in PDB and controls, but significantly reduced resorption in PDB, and with regards to autophagy, PDK1 inhibition was more potent in PDB than in controls. Therefore PDK1/Akt signaling represents an important checkpoint to PDB osteoclast activation. In sum, these results demonstrate the importance of several p62-associated kinases in the over-activation of pagetic osteoclasts, through increased survival and altered signaling. As p62 mutations alone do not account for most cases of PDB, the characterization of these pathways may identify a common factor linking pagetic osteoclasts. Therefore these studies represent a novel approach to osteoclast apoptosis, activation, and autophagy associated with PDB.

Mutations within the SQSTMl gene occur in 25-30% of patients with familial Paget's disease of bone (POB). Over 30 mutations have been described which commonly affect the C-terminal ubiquitin-associated (UBA) domain of the p62 protein, which SQSTMl encodes. In order to gain an understanding into how these mutations exert their effects I investigated the impact of several on p62 protein function and structure. Notably, over-expression of truncating mutants of p62, which genotypephenotype analyses suggest to be associated with more severe POB than common missense mutants, was previously suggested to be associated with greater activation of NF-KB activity than missense mutants in reporter assays. These observations led to the simple hypothesis that changes in p62'S ability to regulate (RANK-mediated) NF-KB signalling are directly related to disease severity in POB patients. In further support of this notion, I found that, A4270 a rare missense mutant of p62 associated with very severe POB produced a level of activation of NF-KB activity above that seen for any other mutant (including truncating mutants). All the POB-associated p62 mutants tested did not impact on p62'S interactions with aPKC and CYLO in co-immunoprecipitation studies. Conversely, unlike all the other POB-associated mutants tested, the non-UBA S349T mutant was not associated with activation of basal NF-KB signalling, but directly affected the interaction of p62 with Keapl; selectively inhibiting Nrf2 signalling. These observations highlight the complexities of disease aetiology in POB and suggest that in addition to dysregulated NF-KB signalling, aberrant production of oxidative response genes may be related to disease mechanism in some POB patients. As an example of a relatively common POB-associated p62 mutation, the 1424S missense mutant was further structurally characterised in the UBA model. Biophysical analysis of the I424S-UBA revealed that the mutation caused major structural rearrangement of the entire UBA domain; a 11 r significantly weakened UBA dimer; and a destabilised UBA-monomer altogether resulting in weakening of the binding affinity for ubiquitin. The interplay between the PDB-associated mutations and phosphorylation of the p62-UBA was also investigated as recently it was reported that phosphorylation of the UBA domain at S403 enhances ubiquitin-binding function. In mouse macrophage samples homozygous for the PDB-associated P394L-p62 mutation (equivalent to the most common P392L mutation in humans) increased phosphorylation of p62 at S403 was detected compared to heterozygotes and wild-type samples. Using UBA-phosphomimetic mutants I confirmed an enhanced ability to bind ubiquitin through weakening the UBA dimer. However the effects of the phosphomimetic mutation were found to further exaggerate the difference in binding affinity between wild-type and PDB-mutant (1424S) UBA domains, presumably due to the PDB mutation disrupting the UBA's structural integrity and weakening the binding interface. Although phosphorylation causes only small changes in binding affinity, this effect is likely to be amplified by avidity in vivo along with the larger effects of the PDB mutations. III

Paget’s disease (PDB) is the second most common metabolic bone disease after osteoporosis, affecting up to 3% of adults over age 55. It is characterized by focal lesions of bone resorbed by hyperactive osteoclasts coupled with rapid formation of highly disorganized, low quality bone formed by osteoblasts. Such lesions cause skeletal deformity, fractures, and other symptoms that significantly decrease quality of life. In 2001, mutations in the SQSTM1/p62 gene were found in a subset of Paget’s patients. The work summarized in this dissertation sought to answer two broad questions: what is the function of p62 in normal bone homeostasis and how do PDB-associated mutations alter it? These studies took advantage of two mouse models: p62 knock-out (KO) mice, and p62P394L “knock-in” (KI) mice carrying the most common PDB-associated mutation. KO, KI, and wildtype (WT) controls were aged to one year for skeletal-histological characterization. No differences were observed in a variety of bone parameters between WT and KO bones, while bones from age-matched KI mice exhibited a 33% decrease in bone volume and a 25% increase in osteoclast formation. In vivo, TNF-α caused a potent induction of osteoclastogenesis in calvariae of WT and KI, but not KO, mice. In vitro, RANKL induced osteoclast formation in a dose-dependent manner in WT and KI, but not KO, cultures. Gene expression profiling of RANKL-treated osteoclast progenitors from WT, KO, and KI mice was then performed to identify the changes in signaling pathways responsible for these effects. Surprisingly, gene expression patterns from all three groups were consistent with robust activation of NFκB signaling in RANKL-treated samples, indicating that p62 is dispensable for RANKL activation of NFκB. Interestingly, gene expression patterns in KO cells suggested impaired proliferation and response to reactive oxygen species (ROS), a finding which was confirmed in cell culture experiments. In contrast, KI cells displayed enrichment for genes associated with the unfolded protein response, consistent with p62’s role in ubiquitin-mediated protein degradation via proteolysis and autophagy. These studies have therefore generated several novel hypotheses concerning the role of p62 in both normal bone homeostasis and Paget’s disease of bone.

La malaltia òssia de Paget (MOP) es caracteritza per ser un trastorn crònic i focal del remodelat ossi que comporta a l’aparició de complicacions com deformitats òssies, artropatia i fractures. La MOP presenta una gran variabilitat en la seva distribució en funció de l’edat, gènere, ètnia i àrea geogràfica. Recents estudis han descrit canvis seculars pel que fa a la prevalença, incidència i gravetat al diagnòstic de la MOP, mostrant una disminució en les últimes dècades. La MOP es considera actualment una malaltia multifactorial amb participació de factors ambientals i genètics. El gen que ha mostrat major susceptibilitat és el Sequestosoma1 (SQSMT1), les mutacions descrites en ell no explicarien de manera completa la patogènia de la MOP. En l’actualitat, són escassos els estudis sobre variacions genètiques en els gens TNFRSF11B i TNFRSF11A associats a MOP clàssica així com l’existència d’interaccions genètiques entre els dos gens i el gen SQSMT1, que condueixi a un increment de risc de MOP i fins i tot que influeixen en el seu fenotip. Amb la finalitat d’investigar el patró de comportament clínic-epidemiològic com genètic de la MOP de la nostra població de baixa prevalença, ens plantegem els següents objectius. Els objectius es van centrar en avaluar canvis en l’evolució del percentatge de nous diagnòstics de la MOP durant el període 1970-2009 i descriure en aquests pacients diferències pel que fa a la severitat al diagnòstic. Així com analitzar la importància d’alteracions moleculars en el gen SQSTM1 i la presència de variacions al·lèliques en els gens TNFRSF11B i TNFRSF11A, tant en la susceptibilitat per al desenvolupament de la MOP com la influència en el seu fenotip. Pacients i Mètodes: Estudi descriptiu ambispectiu observacional de pacients procedents de l’Hospital de la Mar-Parc de Salut Mar (Barcelona), una àrea de baixa prevalença. Es van incloure 393 pacients, diagnosticats entre 1970 i 2009. L’estudi molecular es va dur a terme mitjançant el genotipatge de les 21 variants polimòrfiques per a l’estudi dels gens TNFRSF11B i TNFRSF11A, així com la seqüenciació de el gen SQSTM1 en una població de 200 pacients afectes de MOP i 200 controls hipernormales. Resultats: En l’estudi s’observa un descens progressiu del percentatge del nous diagnòstics de MOP en relació a la població de referència, entre 1994 i 2009, més marcat en el grup de ≥ de 65 anys. Així mateix, s’ha constatat que els pacients afectes de MOP presenten una disminució en l’activitat biològica de la malaltia, una menor extensió de la malaltia i una major edat de presentació al diagnòstic, en funció de l’any de naixement i any del diagnòstic. En contraposició, s’ha observat major severitat en el moment del diagnòstic en els pacients amb edats al diagnòstic de <45 anys i ≥75 anys. S’han identificat 5 factors independents de mal pronòstic al diagnòstic, que afavoriran pitjors desenllaços. Pel que podem concloure, que en el moment de diagnòstic de MOP, l’expressió de la malaltia és menys severa i esdevé de forma més tardana. Els resultats de l’estudi molecular destaquen l’associació significativa entre els SNPs rs3018362 i rs1805034 del gen TNFRSF11A i rs11573871 del gen TNFRSF11B amb l’increment de risc de desenvolupar MOP així com la influència en el seu fenotip. Així mateix es va observar que la presència de l’al·lel T en el polimorfisme rs6567274 del gen TNFRSF11A es va associar amb una disminució de risc de desenvolupar la MOP, així com a un fenotip més lleu. En l’estudi molecular del gen SQSTM1 es van identificar 6 variants genètiques “missense” de nova descripció, associades amb una major susceptibilitat de desenvolupament de la MOP.
La enfermedad ósea de Paget (EOP) se caracteriza por ser un trastorno crónico y focal del remodelado óseo que conlleva a la aparición de complicaciones como deformidades óseas, artropatía por vecindad y fracturas. La EOP presenta una gran variabilidad en su distribución en función de la edad, género, etnia y área geográfica. Recientes estudios han descrito cambios seculares en cuanto a la prevalencia, incidencia y gravedad al diagnóstico de la EOP, mostrando una disminución en las últimas décadas. La EOP se considera actualmente una enfermedad multifactorial con participación de factores ambientales y genéticos. El gen que ha mostrado mayor susceptibilidad es el Sequestosoma1(SQSMT1), las mutaciones descritas en él no explicarían de forma completa la patogenia de la EOP. En la actualidad, son escasos los estudios acerca de variaciones genéticas en los genes TNFRSF11B y TNFRSF11A asociados a EOP clásica así como la existencia de interacciones genéticas entre ambos genes y el gen SQSMT1, que conduzca a un incremento de riesgo de EOP e incluso que influya en el fenotipo. Con la finalidad de investigar el patrón de comportamiento clínico-epidemiológico como genético de la EOP de nuestra población de baja prevalencia, nos planteamos los siguientes objetivos. Los objetivos se centraron en evaluar cambios en la evolución del porcentaje de nuevos diagnósticos de EOP durante el periodo 1970-2009 y describir en dichos pacientes diferencias en cuanto a la severidad al diagnóstico. Así como así como analizar la importancia de alteraciones moleculares en el gen SQSTM1 y la presencia de variaciones alélicas en los genes TNFRSF11B y TNFRSF11A, tanto en la susceptibilidad para el desarrollo de la EOP como la influencia en su fenotipo. Pacientes y Métodos: Estudio descriptivo ambispectivo observacional de pacientes procedentes del Hospital del Mar-Parc de Salut Mar (Barcelona), un área de baja prevalencia. Se incluyeron 393 pacientes, diagnosticados entre 1970 y 2009. En base al estudio molecular se llevó a cabo el genotipado de las 21 variantes polimórfica para el estudio los genes TNFRSF11B y TNFRSF11A, así como la secuenciación del gen SQSTM1 en una población de 200 pacientes afectos de EOP y 200 controles hipernormales. Resultados: En el estudio se observa un descenso progresivo del porcentaje de nuevos diagnósticos de EOP en relación a la población de referencia, entre 1994 y 2009, más marcado en el grupo de ≥ de 65 años. Asimismo, se ha constatado que los pacientes afectos de EOP presentan una disminución en la actividad biológica de la enfermedad, una menor extensión de la enfermedad y una mayor edad de presentación al diagnóstico, en función del año de nacimiento y año del diagnóstico. En contraposición, se ha observado mayor severidad en el momento del diagnóstico en los pacientes con edades al diagnóstico de <45 años y ≥75 años. Se han identificado 5 factores independientes de mal pronóstico al diagnóstico, que van a favorecer peores desenlaces. Por lo que podemos concluir, que en el momento de diagnóstico de EOP, la expresión de la enfermedad es menos severa y acontece de forma más tardía. Los resultados del estudio molecular destacan la asociación significativa entre los SNPs rs3018362 y rs1805034 del gen TNFRSF11A y rs11573871 del gen TNFRSF11B con el incremento de riesgo a desarrollar EOP así como la influencia en su fenotipo. Asimismo se observó que la presencia del alelo T en el polimorfismo rs6567274 del gen TNFRSF11A se asoció con una disminución de riesgo a desarrollar la EOP, así como a un fenotipo más leve. En el estudio molecular del gen SQSTM1 se identificaron seis variantes genéticas "missense" de nueva descripción, asociadas todas ellas a una mayor susceptibilidad en el desarrollo de la EOP.
Paget’s Disease of Bone (PDB) is characterized by a chronic and focal disorder of bone remodeling that leads to the appearance of complications as bone deformities, osteoarthritis and fractures. The PDB presents a great variability in its distribution depending on the age, gender, ethnics and geographic area. Recent studies have described secular changes in the prevalence, incidence and severity at diagnosis of PDB, showing a decline in the last decades. PDB is currently considered a multifactorial disease involving environmental and genetic factors. The gene which has shown higher susceptibility is the Sequestosome-1 (SQSTM1), the mutations described in it would not be able to explain completely the PDB pathogenesis. Nowadays, there are few studies on genetic variations in the TNFRSF11B and TNFRSF11A genes associated with classic PDB, as well as the existence of genetic interactions between both genes and the SQSMT1 gene, leading to an increased risk of PDB or even influencing the phenotype. To investigate the pattern of clinical-epidemiological and genetic behavior of the PDB in our low prevalence population, we propose the following objectives. The objectives were focused on evaluating changes in the evolution of the percentage of new PDB diagnoses during the period 1970-2009 and to describing in those patients differences in terms of severity at diagnosis. As well as to analyze the importance of molecular alterations in the SQSTM1 gene and the presence of allelic variations in the TNFRSF11B and TNFRSF11A genes, both in the susceptibility for the development of PDB and its influence on the phenotype. Patients and Methods: Descriptive, ambispective observational study of patients from Hospital del Mar-Parc de Salut Mar (Barcelona), a low prevalence area. 393 patients, diagnosed between 1970 and 2009, were included. Based on the molecular study, the genotyping of the 21 polymorphic variants was carried out for the study of the TNFRSF11B and TNFRSF11A genes, as well as the sequencing of the SQSTM1 gene in a population of 200 PDB affected patients and 200 hypernormal controls. Results: The study observed a progressive decrease in the percentage of new PDB diagnoses in relation to the reference population, between 1994 and 2009, more marked in the group ≥65 years old group. Thereby, it has been confirmed that the PDB-affected patients show a decrease in the biological activity of the disease, a lower extension of the disease, and a higher age of presentation at diagnosis, depending on the year of birth and the year of diagnosis. In contrast, it has been observed higher severity at diagnosis in patients with ages at diagnosis <45 years and ≥75 years. Five independent factors of poor prognosis at diagnosis have been identified, which will favor worse outcomes. We can conclude, that at the time of diagnosis of PDB, the expression of the disease is less severe and occurs later. The results of the molecular study highlight the significant association between SNPs rs3018362 and rs1805034 of the TNFRSF11A gene and rs11573871 of the TNFRSF11B gene with the increased risk of developing PDB as well as the influence on its phenotype. Thereby, it was observed that the presence of the T allele in the polymorphism rs6567274 of the TNFRSF11A gene was associated with a decreased risk of developing PDB, as well as a milder phenotype. In the molecular study of the SQSTM1 gene, six newly described “missense” genetic variants were identified, all associated with greater susceptibility in the development of PDB.
Universitat Autònoma de Barcelona. Programa de Doctorat en Medicina

La maladie de Paget est une ostéopathie caractérisée par une augmentation multifocale du remodelage osseux, qui débute par un front de résorption osseuse, suivi d'une formation osseuse excessive, avec un remodelage anarchique et intense. Les ostéoclastes "OCs" impliqués dans la phase initiale sont les cellules responsables dans l'initiation du processus pagétique. Les OCs pagétiques sont caractérisés par une résistance à l'apoptose, et des anomalies du processus de l'autophagie "en particulier défaut d'induction"; afin de voir si ces deux caractéristiques étaient liées, nous avons émis l'hypothèse d’un rôle des complexes Bcl2-Beclin1. Beclin-1 est une protéine inductrice de l'autophagie qui peut lier les protéines anti-apoptotiques de la famille Bcl-2; Bcl-2 inhibe alors Beclin-1 "et donc l'induction de l'autophagie" en conservant ses fonctions anti-apoptotiques. Dans le but d'étudier l'impact de l'expression de Bcl2 sur l’autophagie dans les OCs humains, nous avons utilisé un modèle de différenciation in vitro à partir de monocytes dérivés de sang de cordon ombilical, cultivés en présence de RANKL et MCSF pendant 21 jours. Ces conditions permettent d'obtenir des cellules multinucléées au phénotype ostéoclastique. Pour augmenter l’expression de Bcl-2 dans les OCs et analyser son impact sur l’autophagie par interaction avec Beclin-1, les cultures ont été stimulées par TNFα ou RANKL dans le but d'induire une activation de NF-κB. L'expression de Beclin1 et Bcl2 a été confirmée par immunobuvardage dans les OCs. L’autophagie était induite dans les cultures réalisées en conditions stringentes "milieu pauvre en nutriments", sans variation de l'expression de Bcl2 ou Beclin 1 selon les conditions, et sans impact de TNFa ou RANKL. TNFa stimulait de manière significative l'activation de NF-kB dans les cellules HEK mais pas dans les OCs. Toutefois, et quelque soit les conditions, les immunoprécipitations ne permettaient pas de retrouver d'association entre Beclin1 et Bcl2. En revanche, le partenaire d'interaction classique de Beclin1, PI3K type III, était associé à Beclin1. En conclusion, notre travail n'a pas permis d'étudier la formation des complexes Beclin1/Bcl2 et les relations entre apoptose et autophagie, en partie du fait de la complexité du modèle "effets multiples de NF-kB et TNFa" ce qui n'exclut pas l'hypothèse initiale "à ré-évaluer par une méthodologie plus appropriée". En revanche les différentes techniques d'analyse sont maintenant au point pour la poursuite de l'étude.
Abstract : Paget's disease is an osteopathy characterized by a multifocal increase in bone remodeling, which begins with excessive bone resorption followed by increased bone formation. Osteoclasts "OCs" were incriminated in the initiation of the pagetic process. Pagetic OCs are characterized by a resistance to apoptosis, and abnormalities in the process of autophagy “in particular induction defect”. In order to define whether these two characteristics were linked, we hypothesized the role of Bcl2-Beclin1 complexes. Beclin-1 is an autophagy-inducing protein that can bind anti-apoptotic proteins of the Bcl-2 family; Bcl-2 then inhibits Beclin-1 "and thus the induction of autophagy" while retaining its anti-apoptotic functions. To study the impact of Bcl2 expression on autophagy in human OCs, we used an in vitro differentiation model that uses monocytes, which are derived from umbilical cord blood and grown in the presence of RANKL and MCSF for 21 days. These conditions make it possible to obtain multinucleated cells with an osteoclastic phenotype. To increase the expression of Bcl-2 in OCs and analyze its impact on autophagy due to its interaction with Beclin-1, cultures were stimulated with TNFα or RANKL in order to induce NF-κB activation. The expression of Beclin1 and Bcl2 was confirmed by immunoblotting of Ocs cell lysates. Autophagy was induced in cultures carried out under stringent conditions "nutriment-deprived mediun", but we did not observe any variation in the expression of Bcl2 or Beclin 1 according to the culture conditions or TNFα or RANKL stimulation. TNFα significantly stimulated the activation of NF-κB in HEK cells but not in OCs. However, whatever the conditions, results from immunoprecipitaion experiments did not reveal any association between Beclin1 and Bcl2. On the other hand, the classic interaction partner of Beclin1, PI3K type III, was associated with Beclin1. In conclusion, our work did not allow us to demonstrate the formation of Beclin1 / Bcl2 complexes and the relationship between apoptosis and autophagy, partly because of the complexity of the model "multiple effects of NF-κB and TNFα". Our initial hypothesis should thereby be re-evaluated using a more appropriate methodology. On the other hand, the different techniques are now ready for further study.

Paget’s disease of bone (PDB) is an age-related metabolic bone disease characterized by focal lesions of increased bone resorption and formation, eventually leading to bone deformities. The cause of PDB and the mechanisms that give rise to focal lesions are yet to be understood, but findings suggest that the disease is driven by aberrant, highly nucleated, osteoclasts (OCs). In recent years evidences of a genetic involvement were found: mutations in UBA domain of SQSTM1, which encodes for p62, have been reported in both familial and sporadic cases of PDB (P392L most commonly). Although, their actual pathogenicity has been controversial in experimental studies. Moreover, mutations only involve a part of PDB cases and, although some novel genes have been more recently associated to PDB (e.g.ZNF687), the genetic background of PDB remains in part unknown. In an attempt to establish an experimental model of PDB and better understand p62 role in the disease, we compared two genetically modified murine models, systemic p62 knock-out (p62KO) and mutated p62-P394L (P394L) mice. To further characterize the genetic background of PDB we investigated PDB-associated genes and novel genes in SQSTM1-negative patients. In vitro bone marrow-derived macrophages (BMMs) showed a reduced RANKL-induced osteoclastogenesis (OCgenesis) in p62KO-mice, also seen by TRAP staining on bone sections. BMMs of P394L mice showed a higher sensitivity to RANKL and an increase in OC size and number of nuclei, resembling PDB. Such alterations did not result in a bone phenotype at 6 months of age in either model. However, we found that, with ageing, 47% of P394L mice do develop focal osteolytic lesions. Surprisingly, 78% of p62KO mice developed severe lesions. Although further histological characterization is needed, both animals showed focal, PDB-like, osteolytic/sclerotic features. In vitro analysis of aged p62KO BMMs no longer showed a reduction in OCgenesis potential. Taken together, our findings suggest that p62 mutations in UBA cause a loss of function mechanism in PDB, further exacerbated by total loss of the protein. In support of our hypothesis, proteomics showed that aged p62KO and P394L BMMs are primed for OCgenesis and both present similar expression profiles. Investigating possible molecular mechanisms, we found that UBA-dependent p62 functions of autophagy and NF-κB signalling are not altered in either p62KO and P394L cells. Genetic analysis of 34 patients was performed on genes SQSTM1, TNFRSF11A, VCP, ZNF687 and two variants on TM7SF4 and RIN3. The majority of our cohort was negative for rare mutations on such genes, apart from three cases, carrying TNFRSF11A_M566L, SQSTM1_S275N and ZNF687_P937R. Finally, taking advantage of a large pedigree of a severely affected PDB family we performed Exome NGS to identify novel causal gene. Analysis of impact, familial segregation and allelic frequency identified a novel mutation: PFN1_D107Rfs*3, that causes loss of C-terminal domain of PFN1. This gene encodes for profilin1, a regulator of actin polymerization and cell motility. Given the essential role of cytoskeleton reorganization in OCs biology and the previous findings of bone focal deformities in PFN1 OC-conditional knock-out mice, we started investigating its potential pathogenicity. Silencing of PFN1 in murine BMMs resulted in larger OCs with a higher number of nuclei and increased resorption activity. Screening of PFN1 mutations on other PDB cases is ongoing. Overall, our data demonstrated that both p62 depletion and P394L mutation and are sufficient to cause PDB-like disease in mice. Based on the available molecular data the likely role of p62 in PDB is UBA-dependent but autophagy and NF-κB independent. The genetic background of PDB remains largely unknown, as demonstrated by our screening. Finally, the gene discovery part of the project allowed to identify a likely novel gene for PDB, associated with an early onset and aggressive phenotype.

SUMOylation and ubiquitination are important post-translational modifications. While ubiquitination is well known for targeting proteins for degradation, SUMOylation often regulates the intracellular localization of substrates. In the first project of this dissertation, we developed proteomic strategies to identify novel SUMOylated proteins in mammalian cells. In the second project, we investigated the regulation of protein ubiquitination in the NF-κB signaling pathway in the context of Paget’s disease of bone (PDB). Identification of SUMOylated proteins has been a challenge because of low abundance of SUMOylation substrates. Here, we utilized a mass spectrometry (MS)-based proteomic approach to identify novel SUMOylated proteins in mammalian cells. Seventy-four unique proteins were commonly identified in the collection of four SUMO-1 plasmids, thus considered candidate SUMOylated proteins. Many of these proteins are associated with the nucleus. The results were validated by confirming SUMOylation of a novel substrate Drebrin and a well known substrate Ran-GAP1. Furthermore, the potential SUMOylation sites in Drebrin have been identified and confirmed using site-directed mutagenesis. PDB is a disorder characterized by increased bone turnover containing hyperactive osteoclasts. Mutations in Sequestosome 1 (p62) are associated with 40% of familial PDB. P62 is a scaffold protein and plays a critical role in regulating ubiquitination of TRAF family signaling molecules and mediating the activation of NF-κB by RANK and TNFα ligands. P62 also plays a critical role in shuttling substrates for autophagic degradation. The objective of this project is to determine the effects of PDB-associated p62 mutants on NF-κB signaling and autophagy. We compared the effect of wild-type (WT) p62 and PDB mutations (A381V, M404V and P392L) on the TNFα-induced NF-κB signaling using an NF-κB luciferase assay. Our results show that these p62 mutations increased the NF-κB signaling. In addition, we found that the PDB mutations did not change the interaction between p62 and the autophagy marker protein LC3. In summary, the PDB mutations in p62 are likely gain-of-function mutations that can increase NF-κB signaling and potentially contribute to disease progression. Based on the results, we proposed a model to speculate the synergetic role of p62 PDB mutant on NF-κB signaling and autophagy.

Paget's disease of the vulva and breast are rare diseases. Unlike Paget's disease of the breast, where the consensus is that the great majority of cases are associated with an in-situ or invasive ductal carcinoma, only approximately 10-30% of cases of Paget's disease of the vulva have an invasive adenocarcinoma present. It is believed that the Paget cells in Paget's disease of the breast are derived from the underlying in-situ or invasive breast carcinoma, and these cells migrate up through the ducts onto the nipple epidermis. The histogenesis underlying vulval Paget's disease is unclear. Paget's disease of the vulva may become secondarily invasive even in the absence of an underlying malignancy. The aim of the study was to identify abnormalities present in Paget's diseases of the vulva and the breast and to investigate whether there are any differences in molecular markers in the Paget cells of those cases with invasive disease compared to those cases without invasive disease. Such an analysis may identify some of the molecular pathways underlying both vulval and breast Paget's disease, as well as generating potential markers for clinical prognosis. Archival paraffin wax-embedded sections of Paget's disease of the vulva or breast were used. Immunohistochemical analysis was performed to analyse markers involved in the cell cycle (p53, pRb, cyclin Dl, Ki67), in angiogenesis (e.g. VEGF, PD-ECGF/TP, MVD) and cell adhesion molecules (e.g. plakoglobin, E-cadherin, (3-catenin)). Sections that were immunopositive for the tumour marker p53 were microdissected, the DNA extracted, amplified and sequenced. In situ hybridisation was also used to determine the presence of mRNA of the adhesion molecules in the tissue sections. A national register for Paget's disease of the vulva was established requesting that clinicians who have patients with Paget' s disease of the vulva should enrol them. Results suggest E-cadherin, plakoglobin and pRb and p53 may have a role to play in the pathogenesis of Paget's disease of the vulva and pRb, plakoglobin, VEGF and PD-ECGF/TP in Paget's disease of the breast. Wide local excison was the preferred treatment option for patients registered in the PDV database. The information from the Paget's register and the results obtained from the thesis may increase the understanding of Paget's disease of the vulva and breast.

In order to identify novel genes which were expressed in Paget's disease, the Differential Display PCR technique was used to compare gene expression in samples of Pagetic and normal bone, and in human bone long term marrow cultures. Several genes appeared to be differentially expressed in Pagetic bone in comparison to controls, however the display patterns were difficult to interpret and consistent differences were not observed. Pagetic marrow cultures were studied and were found to be abnormal in that osteoclast-like cell formation was 20-fold higher in Pagetic marrow than in age-matched controls. This study also examined Pagetic marrow samples aspirated from both affected and unaffected sites, and it was found that large numbers of oseteoclast-like cells formed in Pagetic cultures regardless of the site of marrow aspiration, suggesting that there may be an abnormality in osteoclast precursors in Paget's disease. Differential display of these marrow samples revealed consistent differences in gene expression between Pagetic and normal marrow, and of four differentially expressed mRNAs which were cloned and sequenced, one was selected for further study owing to its significant homology to murine Centrosomin A, a gene thought to be involved in cell cycle division and microtubule formation. The centrosomin-like DD clone was confirmed to be significantly over-expressed in Pagetic marrow by semi-quantiative PCR, and using 232bp DD product as a probe, a ZAP Express osteoclastoma cDNA library was screened by hybridisation to identify cross-hybridising clones. Thirty four positive clones were identified, and two of these clones, CLC 1 and CLC 2, were isolated and sequenced. Database searches identified CLC 2 (4kb) as being a partial clone of human eukaryotic translation initiation factor-3 (eIF-3) - p180 subunit. Further characterisation of both CLC-1 and 2 may provide important information on their functions, both within the cell and their possible role in Paget's disease.

Orientador: Laurival Antonio De Luca
Resumo: O objetivo deste trabalho foi estudar através do exame Imunoistoquimico, a correlação entre alguns fatores Anatomopatológicos (tipo histológico e grau nuclear) e alguns fatores biológicos (receptores hormonais de estrógeno e de progesterona, proteína c-erbB-2 e proteína p53, no carcinoma de Paget da mama, doença rara e especial. No período entre Janeiro de 1980 a Dezembro de 1998 foram tratados no Instituto Brasileiro de Controle do Câncer, 6.303 casos de câncer de mama, deste total 98 casos foram diagnosticados como carcinoma de Paget, cuja incidência foi de 1,55%. Estudamos retrospectivamente 60 casos, sendo que 38 deles foram excluídos da análise, devido a limitação e escassez da amostra no material disponível, a idade das pacientes variou entre 26 e 84 anos, com média de 55,4 anos, as informações clínicas e terapêuticas foram obtidas dos prontuários das pacientes considerando, idade na época do diagnóstico, tamanho do tumor quando palpável, estadiamento clínico, e o tipo de cirurgia realizada. As amostras de tecido mamário foram recuperadas dos arquivos do Departamento de Anatomia Patológica do I.B.C.C. / MATTOSINHO. Após a revisão histológica, realizada por dois patologistas os casos foram classificados em quatro grupos: Grupo A- Doença de Paget (forma pura) n = 09 Grupo B- Doença de Paget + neoplasia ductal "in situ", n = 12 Grupo C- Doença de Paget, neoplasia ductal invasora, n = 30 Grupo D- Doença de Paget + neoplasia ductal "in situ"+ neoplasia ductal invasora, n = 09. Entre as variáveis anatomopatológicas, o grupo C prevaleceu com 30 casos (50%). O grau nuclear (GN-II) predominou com 45 casos (75%). Em relação as variáveis biológicas o receptor de estrógeno negativo predominou com 41 casos (68,3%), seguido pelo receptor de progesterona negativo com 40 casos (66,7%), podemos dizer que... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of this paper was to study the immunohistochemical efects of Paget's disease, a rare and special carcinoma of the breast, by correlating anatomopathological (histological and nuclear grade) and biological (estrogen and progesterone hormonal receptors, c-erbB-2 protein and p53 protein) factors. Between January 1980 and December 1998, 6303 cases of breast cancer were treated at the Brazilian Institute of Cancer Control; 98 of these were diagnosed with Paget's carcinoma, an incidence of 1.55%. We retrospectively studied 60 of these cases; 38 were excluded due to lack of available sample material. Patient age varied between 26 and 84 years (mean 55.4), clinical and therapeutic information were obtained from patient's medical records considering age at time of diagnosis, tumor size when palpable, clinical stage, and type of surgery performed. Samples of breast tissue were retrieved the Anatomical Pathology Department, I.B.C.C. / MATTOSINHO. After histological review, by two different pathologists, they were classified into four groups: Group A- Paget's disease (pure form) n = 09 Group B- Paget's disease + "in situ" duct neoplasia n = 12 Group C- Paget's disease, invasive duct neoplasia n = 30 Group D- Paget's disease + "in situ" duct neoplasia + invasive duct neoplasia n = 09.Invasive duct neoplasia was the most prevalent anatomopathological variable (Group C, n = 30, 50%). Nuclear grade (GNII) was found in 45 cases (75%). In relation to the biological variables, the negative estrogen receptor was predominant with 41 cases (68.3%), followed by the negative progesterone receptor with 40 cases (66.7%); this correlation had good concordance by the Kappa test. The c-erbB-2 protein was positive in 53 cases (88.3%) and p53 was negative in 47 cases (78.3%). From these results, we concluded that there was no statistical... (Complete abstract click electronic address below)
Doutor

Over the past several decades, life expectancy for patients with cystic fibrosis (CF) has increased significantly. As patients live longer, other nonpulmonary co-morbidities related to CF have become increasingly prevalent, including CF-related bone disease. Because CF related bone disease has only recently emerged as a clinical problem, and the underlying bone alterations and pathogenesis of this condition have not been established. This thesis explores the underlying bone micro-architecture and strength alterations found in adults with CF using state-of-the-art bone imaging techniques and explores whether improvements in the treatment of patients with CF over the past 15 years has led to similar improvements in bone health.

Joint degeneration requiring arthroplasty surgery and the consequences of osteoporosis are the two fundamental pathologies in orthopaedics. There are around 44,000 Medline-indexed journals about osteoporosis, and around 30,000 concerned with arthroplasty. However despite both typically occurring in a similar elderly population, only 350 (less than 0.5%) are cross-indexed. Aseptic loosening is the commonest cause of hip arthroplasty failure, with revision surgery being the only current treatment. Recent work has increased the understanding of the aetiology of aseptic loosening and studies suggest that this process may be inhibited by the use of drugs that are normally used to treat osteoporosis, such as the bisphosphonates. It has also been shown that the occult incidence of metabolic bone disease may be as high as 40% in patients undergoing primary hip arthroplasty. This study is a progression of similar work on the aetiology and control of aseptic loosening done in the same department over the proceeding few years. In the first instance a cellular model of aseptic loosening was investigated by Ong and Taylor [published in 2003]. This laboratory based project used mouse bone, and exposing it to interface membrane tissue sampled at the time of revision arthroplasty surgery. This model was described by Reynolds and Dingle in 1970, and shown to activate osteoclasts. Ong and Taylor demonstrated that osteoclast activation could be inhibited with doxycycline, suggesting that matrix metalloproteinases may be important in the pathophysiology of aseptic loosening, and that the process is potentially preventable. The work was progressed further by Ibrahim and Taylor [2004] who developed a live model of particle induced osteolysis. They measured radio-labelled calcium uptake in mouse femora following implantation of ceramic particles, sham surgery and in controls. This was shown to be a useful model of quantifying osteolysis, although they did not find a difference between the controls and those exposed to ceramic particles. The original aim of this work was to follow on from the previous work and demonstrate that osteolysis could be inhibited or reversed using pharmacological agents. Ideally this would be done in a human clinical model, and a number of drugs were considered, including doxycycline, bisphosphonates and statins. Such a project would have involved recruiting patients to a clinical trial, followed by either randomisation to treatment or control groups before commencing treatment on participants. The ideal end-point would be revision for aseptic loosening (although radiological development of loosening would be an alternative). Because hip arthroplasty is such a successful operation these end-points are both rare and often not seen for many years. Even if we assume a rather optimistic reduction in loosening of 50% using our agent, we would have to recruit several hundred participants and wait at least 10 years to get meaningful results. We therefore have had to sacrifice some of the principles of strong research in favour of a project that could be completed with a limited time-frame and a limited budget. We studied patients that had already had an arthroplasty in situ for a number of years, and in view of the multi-factorial nature of loosening (as discussed below), limited this to one type of arthroplasty. The hypothesis of this study is that patients who have an underlying disorder of bone metabolism (such as osteoporosis or vitamin D deficiency) are more likely to develop aseptic loosening. In addition we hypothesise that there are measurable clinical, radiographic and biochemical markers that help predict those likely to develop loosening. This hypothesis was investigated in 127 patients (78 patients with a loose cemented total hip replacement matched by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement)/ We then conducted four connected studies involving, clinical, radiological, DEXA and biochemical assessment for markers of loosening. The aims are detailed below, but were principally to see whether patients with loosening are more likely to markers of osteoporosis or poor bone health. Unfortunately, this study takes us no further forward with regard to whether aseptic loosening can be inhibited by specific therapeutic agents, but hopefully it helps us to better understand the pathophysiological processes involved with arthroplasty failure. These can be used in future research to help improve arthroplasty function and longevity.

Chronic kidney disease (CKD) is associated with increased mortality and cardiovascular complications. Disturbances in mineral metabolism occur early <luring the course of CKD and several components of the CKD-mineral and bone disorder (CKD-MBD) are independent predictors of mortality. Alkaline phosphatase (ALP) is necessary for skeletal mineralization and is also involved in the process of vascular calcification. In recent years, ALP has evolved as a strong predictor of mortality in the CKD population. The significant role of ALP in the mineralization process renders it a putative target for the treatment and prevention of vascular calcification. Three circulating isoforms of bone ALP (BALP) have been identified (B/I, B 1, and B2). A fourth isoform, Blx, has been identified exclusively in serum from patients with CKD. The aim of the present thesis was to further elucidate the role ofthe BALP isoforms in CKD with respect to bone abnormalities and vascular calcification. In study I we identified the novel BALP isoform Blx in 20% of patients with mild to moderate CKD. Blx was associated with lower glomerular filtration rate and higher serum phosphate and calcium x phosphate product, which are risk factors for cardiovascular mortality in CKD. We also identified the BALP isoforms B/I, Bl and B2 as predictors of total hip bone mineral density. Study II was an experimental study, investigating the role of the BALP isoforms in phosphate induced calcification of human aortic smooth muscle cells (HASMCs). We found that the ALP expressed in HASMCs is exclusively BALP. Phosphate induced calcification of HASMCs was associated with increased BALP isoforms B/I, Blx, and B2 activities, which implies functional differences between the BALP isoforms in HASMC calcification. In study III we investigated the association of BALP isoforms in serum and histomorphometric parameters of bone in patients on chronic hemodialysis. W e identified the BALP isoform Blx as a novel marker for reduced osteoblastic activity. Study IV was a prospective cohort study of the association of serum BALP isoforms with aortic calcification and vascular stiffness in prevalent chronic dialysis patients. Blx was associated with baseline and time varying vascular stiffness, determined by pulse wave velocity, but not with calcification of the abdominal aorta. We also found an association of Blx with better event-free survival. In conclusion, these studies demonstrate that the BALP isoforms, especially isoform Blx, are involved in different aspects of CKD-MBD. This opens up for further research to identify the BALP isoforms as diagnostic markers and possible treatment targets in CKD-MBD.

Long-term exposure to pharmacological doses of glucocorticoids has been associated with the development of osteopenia and avascular necrosis. Bone loss may be partially attributed to a steroid-induced decrease in the osteoblastic differentiation of multipotent progenitor cells found in the bone marrow. In order to determine if there is a change in the osteogenic potential of the bone marrow stroma following glucocorticoid treatment, Sprague-Dawley rats were administered methylprednisolone for up to six weeks, then sacrificed at 0, 2, 4, or 6 weeks during treatment or 4 weeks after cessation of treatment. Femurs were collected and analyzed for evidence of steroid-induced osteopenia and bone marrow adipogenesis. Although glucocorticoid treatment did inhibit bone growth, differences in ultimate shear stress and mineral content were not detected. The volume of marrow fat increased with increasing duration of treatment, but returned to near control levels after cessation of treatment. Marrow stromal cells were isolated from tibias, cultured in the presence of osteogenic supplements, and analyzed for their capacity to differentiate into osteoblast-like cells in vitro. Glucocorticoid treatment diminished the absolute number of isolated stromal cells, but did not inhibit the relative levels of bone-like mineral deposition or osteocalcin expression and secretion. Although pharmacological glucocorticoid levels induce bone loss in vivo, physiologically equivalent concentrations have been shown to enhance the formation of bone-like tissue in vitro. However, glucocorticoids have also been reported to inhibit proliferation and type I collagen synthesis in marrow stromal cell cultures. In order to assess the effects of intermittent dexamethasone treatment on the progression of osteogenesis in rat marrow stromal cell culture, this synthetic glucocorticoid was removed from the culture medium after a variable period of initial supplementation. Cell layers were analyzed for total cell number, collagen synthesis, phenotypic marker expression, and matrix mineralization. Prolonged supplementation with dexamethasone decreased proliferation, but did not significantly affect collagen synthesis. Furthermore, increased treatment duration was found to increase bone sialoprotein expression and mineral deposition. The duration of glucocorticoid treatment may be a key factor for controlling the extent of differentiation in vitro.
Master of Science

The bone marrow serves as a reservoir for leukocytes and stem cells, from where cells can be mobilised into the circulation and can be recruited to sites of inflammation. Mobilisation of cells out of the bone marrow is dependent on their migration across the bone marrow sinusoidal endothelium, which is thought to be structurally and functionally different to endothelial cells from other vascular beds. In order to characterise the bone marrow endothelium and to study the molecular mechanisms involved in the mobilisation of cells, a protocol to isolate bone marrow endothelial cells and to grow them in vitro was developed. The bone marrow contains a number of distinct progenitor cell populations, including endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs). Whether these populations of stem cells are recruited from the bone marrow to the lungs was investigated in two contrasting models of lung disease: the house dust mite (HDM) model of allergic airways disease and the bleomycin model of pulmonary fibrosis. In the HDM model increased recruitment of EPCs to the inflamed lungs was associated with increased peribronchial angiogenesis, and reduced EPC numbers in the bone marrow. Blocking VEGF inhibited EPC recruitment to the inflamed lungs and reduced the associated peribronchial angiogenesis. In this model, no recruitment of MSCs to the inflamed lungs was observed. However, in the bleomycin model, a significant elevation in MSC numbers was observed in the circulation, lung tissue and BAL fluid. Experiments to block the recruitment of MSCs to the lungs in response to bleomycin injury were performed, along with investigations into the recruitment of exogenously administered MSCs to the injured lungs. A population of MSCs residing in the naïve lungs was identified, which are phenotypically similar to bone marrow MSCs, but can be distinguished by their size and expression of specific cell surface antigens.

To enhance our understanding of the pathophysiology of bone disease associated with liver transplantation and of the mechanisms underlying bone loss in the three month period following transplantation, this prospective study was undertaken as follows: (1) bone pathophysiology was evaluated pre- and three months post-transplantation in transiliac biopsies using tetracycline-assisted histomorphometry; (2) cellular activities of bone formation and resorption pre- and post- transplantation were studied using quantitative enzyme cytochemistry in combination with histomorphometric methods; (3) cellular activities for markers of bone energy metabolism and biosynthesis and/or cell proliferation were investigated using quantitative enzyme cytochemistry; (4) plasma markers for bone metabolism were investigated at regular intervals in collaboration with other laboratories. It was concluded from this study that rapid bone loss early after transplantation is due both to increased bone turnover and a negative remodelling balance at the individual bone remodelling site. These changes were at least partially mediated by increased PTH levels secondary to a negative balance in plasma calcium. Cyclosporin A is known to increase intracellular calcium levels and inhibit calcium release from mitochondria. It also reduces glomerular filtration rate which could be sufficient to depress extracellular calcium levels and thereby cause the observed rise in PTH levels. The consequences of this for post transplant bone remodelling is a markedly enhanced risk of osteoporosis in these patients. Ensuring replete calcium and vitamin D levels pre-transplantation and supplementation of cyclosporin A treatment with vitamin D metabolites and calcium post-transplantation followed by careful monitoring of plasma calcium concentrations might offer a better overall outcome for preventing transplantation-associated osteoporosis at this early stage post transplantation.

Nitric oxide acts as a signalling molecule in several tissues and organ systems and recent work has shown that it is also produced in bone. The aim of this thesis was to investigate the role of the nitric oxide synthase pathway in bone cell function and bone disease. Studies with primary human osteoblasts indicated that they had the ability to produce nitric oxide under conditions of cytokine stimulation using the iNOS pathway and in response to fluid flow using the ecNOS pathway. Cytokine induced nitric oxide had a differentiation-inducing effect as reflected by a decrease in cell proliferation and an increase in the expression of alkaline phosphatase. Further investigations showed that p27Kjpl was induced in response to cytokine stimulation in primary human osteoblasts suggesting that this may have been responsible for cytokine induced inhibition of cell growth. An investigation of the expression of the different isoforms of nitric oxide synthase in human metabolic bone diseases revealed that ecNOS was the predominantly expressed isoform in bone. The primary human osteoblasts also showed widespread expression of ecNOS protein. In view of this, a genetic association study was carried out to investigate the relationship between a polymorphism in the ecNOS gene, bone mineral density and fracture incidence. A significant relationship was found between bone mineral density and presence of the ecNOS polymorphism, but the polymorphism was not found to be associated with osteoporotic fracture. In summary, nitric oxide produced via the inducible nitric oxide synthase pathway in human osteoblast-like cells inhibits cell proliferation and increases cell differentiation. This inhibition of cell proliferation was associated with increased expression of the cell cycle inhibitory protein p27Kipl. ecNOS was shown to be the predominant isoform of nitric oxide synthase expressed under basal conditions and in response in fluid flow. A polymorphism in this gene was shown to be associated with decreased bone mass.

This thesis addresses the definition and the application of formal techniques in the field of Computational Systems Biology, with particular focus on bone remodelling (BR), the cellular process of bone renewal, and on the analysis and control of disease processes. Firstly, we study the multiscale and spatial mechanisms that connects disruptions at the molecular signalling level, to osteoporosis and other diseases characterized by low bone mass and structural weakening at the tissue level. We define a modelling framework based on a formal specification language which extends the Shape Calculus, a process algebra with spatial and geometrical primitives. The executable side is obtained by encoding the specification into an agent-based model, where agents are enriched with stochastic actions and perception. This framework is used to define a novel spatial and individual-based model of bone remodelling, parametrized in order to reproduce both healthy and osteoporotic conditions, and to analyse how the disposition of bone cells affects bone microstructure at the tissue level. Secondly, we propose a methodological study aiming at evaluating and comparing different models of bone remodelling and different techniques for the analysis of bone diseases and of stabilization and homeostasis-related properties. We consider a non-linear ODE model, over which we perform simulation and sensitivity analysis; a stochastic model on which we employ probabilistic model checking; and a hybrid piecewise-multiaffine approximation of the ODEs, supporting model checking and LTL-based parameter synthesis. We extend the model in order to describe osteoporosis and osteomyelitis (a bone infection) and we show how quantitative verification methods could provide clinically meaningful diagnostic estimators. Thirdly, we investigate the use of formal languages and hybrid techniques in the modelling of disease processes and in the synthesis of treatment strategies. In particular, hybrid models allow us to describe the disease dynamics in a continuous fashion, while the scheduling of multiple drugs discretely. We define a process-algebraic language for specifying general disease processes and treatments, called D-CGF (an extension to the CGF process algebra), from which multiple semantics can be derived: stochastic hybrid automata and hybrid dynamical systems. Then, hybrid non-linear control is employed to compute the optimal scheduling of multiple therapies. The approach is applied to an epidemic model of the H1N1 influenza, where we derive the optimal combination of vaccination and antiviral treatments.

京都大学
0048
新制・課程博士
博士(医学)
甲第22143号
医博第4534号
新制||医||1039(附属図書館)
京都大学大学院医学研究科医学専攻
(主査)教授 妻木 範行, 教授 森本 尚樹, 教授 別所 和久
学位規則第4条第1項該当
Doctor of Medical Science
Kyoto University
DFAM