Littérature scientifique sur le sujet « Dendritic cells NLRP3 »

Abstract Histoplasma capsulatum is an opportunistic dimorphic fungal pathogen. Dendritic cells take up Histoplasma yeasts and present antigens to activate both CD4 and CD8 T cells. Therefore, the interaction of dendritic cells with the fungus is critical to host defense against Histoplasma infection. Here, we investigated the mechanism of inflammasome activation in dendritic cells after infection with Histoplasma. Interaction of bone marrow-derived dendritic cells with Histoplasma activated caspase-1 and induced the secretion of IL-1β. Using blocking antibodies we also found that Dectin-2 regulated pro-IL-β gene transcription and caspase-1 activation after Histoplasma infection in dendritic cells. Histoplasma interaction with Dectin-2 triggered both the first (transcription of pro-IL-1β) and the second (activation of caspase-1) signals in response to Histoplasma stimulation. Cells with NLRP3-deficiency failed to activate caspase-1 and to process pro-IL-1β, showing that NLRP3 is an important pattern recognition receptor in the cytosol to control inflammasome activation by Histoplasma. Thus, our results demonstrated that both Dectin-2 and NLRP3 play important roles in inflammasome activation after Histoplasma infection.

Mycobacterium tuberculosis(Mtb) infection activates the NLRP3 inflammasome in macrophages and dendritic cells. Much attention has been paid to the mechanisms for regulation of NLRP3 against Mtb. However, whether epigenetic mechanisms participated in NLRP3 activation is still little known. Here we showed that NLRP3 activation was regulated by DNA methylation modification. Mtb infection promoted NLRP3 activation and inflammatory cytokines expression. NLRP3 promoter was cloned and subsequently identified by Dual-Luciferase Reporter System. The results showed that NLRP3 promoter activity was decreased after methylation by DNA methylaseSssIin vitro. Meanwhile, DNA methyltransferases inhibitor DAC could upregulate the expression of NLRP3. Furthermore, promoter region of NLRP3 gene was demethylated after Mtb H37Rv strain infection. These data revealed that DNA methylation was involved in NLRP3 inflammasome activation during Mtb infection and provided a new insight into the relationship between host and pathogens.

The pathogenesis of Crohn’s disease (CD) involves defects in the innate immune system, impairing responses to microbes. Studies have revealed that mutations NLRP3 are associated with CD. We reported previously that Nlrp3−/− mice were more susceptible to colitis and exhibited reduced colonic IL-10 expression. In the current study, we sought to determine how the loss of NLRP3 might be altering the function of regulatory T cells, a major source of IL-10. Colitis was induced in wild-type (WT) and Nlrp3−/− mice by treatment with dextran sulphate sodium (DSS). Lamina propria (LP) cells were assessed by flow cytometry and cytokine expression was assessed. DSS-treated Nlrp3−/− mice exhibited increased numbers of colonic foxp3+ T cells that expressed significantly lower levels of IL-10 but increased IL-17. This was associated with increased expression of colonic IL-15 and increased surface expression of IL-15 on LP dendritic cells. Neutralizing IL-15 in Nlrp3−/− mice attenuated the severity of colitis, decreased the number of colonic foxp3+ cells, and reduced the colonic expression of IL-12p40 and IL-17. These data suggest that the NLRP3 inflammasome can regulate intestinal inflammation through noncanonical mechanisms, providing additional insight as to how NLRP3 variants may contribute to the pathogenesis of CD.

AbstractSepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sestrin2 (SESN2), a highly evolutionarily conserved protein, is critically involved in the cellular response to various stresses and has been confirmed to maintain the homeostasis of the internal environment. However, the potential effects of SESN2 in regulating dendritic cells (DCs) pyroptosis in the context of sepsis and the related mechanisms are poorly characterized. In this study, we found that SESN2 was capable of decreasing gasdermin D (GSDMD)-dependent pyroptosis of splenic DCs by inhibiting endoplasmic reticulum (ER) stress (ERS)-related nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)-mediated ASC pyroptosome formation and caspase-1 (CASP-1) activation. Furthermore, SESN2 deficiency induced NLRP3/ASC/CASP-1-dependent pyroptosis and the production of proinflammatory cytokines by exacerbating the PERK–ATF4–CHOP signaling pathway, resulting in an increase in the mortality of septic mice, which was reversed by inhibiting ERS. These findings suggest that SESN2 appears to be essential for inhibiting NLRP3 inflammasome hyperactivation, reducing CASP-1-dependent pyroptosis, and improving sepsis outcomes through stabilization of the ER. The present study might have important implications for exploration of novel potential therapeutic targets for the treatment of sepsis complications.

Abstract NLRP3 activation and IL-1β production are implicated in Kawasaki Disease (KD) pathogenesis, however a detailed description of molecular networks and cellular subsets involved is lacking. Here, in a murine model of KD vasculitis, we used single-cell RNA sequencing and spatial transcriptomics to characterize the cellular landscape of vascular tissues and observed infiltrations of innate and adaptive immune cells, associated with increased expression of Nlrp3 and Il1b. Monocytes, macrophages and dendritic cells were the main sources of IL-1β, whereas fibroblasts and vascular smooth muscle cells (VSMCs) expressed high levels of IL-1 receptor. Genetic inhibition of IL-1β signaling on VSMCs efficiently attenuated the development of cardiovascular lesions during murine KD. In addition, pharmacological inhibition of NLRP3 prevented the development of cardiovascular inflammation. Our results unravel the cellular diversity involved in IL-1β production and signaling in KD cardiovascular lesions and demonstrate that therapeutic strategies targeting NLRP3 might be beneficial for human KD.

Inflammation is involved in initiation, development and complications of the vast majority of non-communicable diseases. Recent research demonstrated that infl ammation is involved in pathogenesis of all major cardiovascular diseases. Different endogenous factors (LDL, nucleic acid strands, uric acid – collectively called „Damage Associated Molecular Patterns – DAMPs”) activate dedicated receptors („Pattern Recognition Receptors – PRR”) on monocytes, macrophages or dendritic cells responsible for the innate immunologic response. They have a major role in natural defense mechanisms against different pathogens and in normal conditions have a protective role. Among PRRs „NOD-like, leucin rich, pyrin containing (NLRP)” receptors are a 14-member family located in the cytoplasm. One of these is the NLRP3 resulting from nuclear transcription under the infl uence of NF-kB, a second messenger from membrane PRRs to the nucleus. Mostly the same factors responsible for NLRP3 intracellular expression stimulate its oligomerization resulting in a large protein complex, the NLRP3 infl ammasome. This activates caspase-1 responsible for IL-1b and IL-18 production and initiates an inflammatory reaction leading to various pathologic processes, such as atherosclerosis, hypertension, diabetes and heart failure. This is the current story as we know it of the NLRP3 infl ammasome, a small intracellular component that when inappropriately activated may does more harm than good.

ABSTRACTMicrosporum canisis a pathogenic fungus with worldwide distribution that causes tinea capitis in animals and humans.M. canisalso causes invasive infection in immunocompromised patients. To defy pathogenic fungal infection, the host innate immune system is the first line of defense. As an important arm of innate immunity, the inflammasomes are intracellular multiprotein complexes that control the activation of caspase-1, which cleaves proinflammatory cytokine pro-interleukin-1β (IL-1β) into its mature form. To determine whether the inflammasome is involved in the host defense againstM. canisinfection, we challenged human monocytic THP-1 cells and mouse dendritic cells with a clinical strain ofM. canisisolated from patients with tinea capitis. We found thatM. canisinfection triggered rapid secretion of IL-1β from both THP-1 cells and mouse dendritic cells. Moreover, by using gene-specific shRNA and competitive inhibitors, we determined thatM. canis-induced IL-1β secretion was dependent on NLRP3. The pathways proposed for NLRP3 inflammasome activation, namely, cathepsin B activity, K+efflux, and reactive oxygen species production, were all required for the inflammasome activation triggered byM. canis. Meanwhile, Syk, Dectin-1, and Card9 were found to be involved inM. canis-induced IL-1β secretion via regulation of pro-IL-1β transcription. More importantly, our data revealed thatM. canis-induced production of IL-1β was dependent on the NLRP3 inflammasomein vivo. Together, this study unveils that the NLRP3 inflammasome exerts a critical role in host innate immune responses againstM. canisinfection, and our data suggest that diseases that result fromM. canisinfection might be controlled by regulating the activation of inflammasomes.

Abstract The NLRP3 inflammasome is an essential intracellular mediator of anti-viral immunity. In murine dendritic cells (DCs) this complex responds to a wide array of signals, including ion efflux and influenza A virus (IAV) infection, to activate caspase-1 mediated proteolysis of interleukin (IL)-1β and IL-18 into biologically active cytokines. However, the presence and function of the NLRP3 inflammasome in human DCs in response to various triggers, including viral infection, has not been clearly defined. Here, we delineate the contribution of the NLRP3 inflammasome to the secretion of IL-1β, IL-18, and IL-1α by human DCs. Activation of the NLRP3 inflammasome in human DCs by various synthetic activators resulted in the secretion of bioactive IL-1β, IL-18, and IL-1α, and induction of pyroptotic cell death. Cellular IL-1β release depended on potassium efflux, and the activity of proteins NLRP3 and caspase-1. Similarly, IAV infection of DCs resulted in priming and activation of the NLRP3 inflammasome and secretion of IL-1β and IL-18 in an M2 and NRLP3 dependent manner. The magnitude of priming by IAV varied amongst different strains and inversely corresponded to type I IFN production. To our knowledge, this is the first report describing the existence and function of the NLRP3 inflammasome in human DCs, and the ability of IAV to prime and activate this pathway in human DCs with important implications for anti-viral immunity and pathogenesis.

Generally, a reciprocal antagonistic interaction exists between the antiviral type I interferon (IFN) and the antibacterial nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain containing 3 (NLRP3)-dependent IL-1β pathways that can significantly shape immune responses. Plasmacytoid dendritic cells (pDCs), as professional type I IFN-producing cells, are the major coordinators of antiviral immunity; however, their NLRP3-dependent IL-1β secretory pathway is poorly studied. Our aim was to determine the functional activity of the IL-1β pathway and its possible interaction with the type I IFN pathway in pDCs. We found that potent nuclear factor-kappa B (NF-κB) inducers promote higher levels of pro-IL-1β during priming compared to those activation signals, which mainly trigger interferon regulatory factor (IRF)-mediated type I IFN production. The generation of cleaved IL-1β requires certain secondary signals in pDCs and IFN-α or type I IFN-inducing viruses inhibit IL-1β production of pDCs, presumably by promoting the expression of various NLRP3 pathway inhibitors. In line with that, we detected significantly lower IL-1β production in pDCs of psoriasis patients with elevated IFN-α levels. Collectively, our results show that the NLRP3-dependent IL-1β secretory pathway is inducible in pDCs; however, it may only prevail under inflammatory conditions, in which the type I IFN pathway is not dominant.

Abstract Photodynamic therapy (PDT) has long been known for capable of killing tumor cells and induces anti-tumor immunity. The mechanism of how PDT can enhance anti-tumor response is not clear. We tested the hypothesis that bone marrow derived dendritic cells (BMDCs) activated by PDT-generated tumor cell lysates (PDTTCL) can induce anti-tumor response in Lewis lung carcinoma (LLC), a poorly immunogenic tumor model. We found that LLC tumor growth was retarded by immunization with BMDCs pulsed by PDTTCL. Furthermore, therapeutic effects are observed in preexisting LLC tumor when PDT is combined with PDTTCL treated BMDCs and R848 (TLR7/8 ligand) therapy. This study aims to understand how PDT enhances tumor immunogenicity and provides insight to improve both in situ PDT and PDT vaccine efficacy in combating secondary disease. We found that stimulation of BMDCs with PDTTCL leads to dramatic increase in pro-inflammatory cytokine production, including IL-1β, which plays a critical role in PDT efficacy. Previous studies have shown that production and activation of IL-1β require both TLR signaling and activation of NLRP3 inflammasome. IL-1β production induced by PDTTCL in BMDCs is MyD88 dependent, but the activation of IL-1β appears to be dependent upon elastase and proteinase 3 rather than NLRP3 inflammasome. Together, our findings reveal a novel mechanism of IL-1β activation in BMDCs that does not require NLRP3 inflammasome in response to danger signals from tumor cell lysates.

Dendritic cells play a central role in the regulation of innate and adaptive immunity, and exert their sensor functions through a plethora of receptors, including the NLRP3-inflammasome. The role of NLRP3-inflammasome in sensing endogenous danger signals, such as MSU, has been deeply investigated in the last years. However the exact mechanism of MSU activation of DCs through NLPR3 is not completely defined yet. Moreover, little is known about the adjuvant role of MSU as promoter of DC- mediated priming of specific T cell subsets. Starting from these observations, the present work aims to describe evidences of the role of endogenous danger signals in the activation of the immune system. In particular, we investigated which is the role of MSU and its putative receptor NLRP3 in the activation of DCs and how this process is involved in starting both innate and adaptive immunity.

Orientador: Ronei Luciano Mamoni
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-27T05:56:25Z (GMT). No. of bitstreams: 1 Castro_LiviaFurquimde_M.pdf: 5966667 bytes, checksum: bd25c56ae25a8825069884bedd9ca8ce (MD5) Previous issue date: 2015
Resumo: Diversos estudos demonstram que a resposta inflamatória é de extrema importância para o controle da Paracoccidioidomicose (PCM). Essa resposta inflamatória é iniciada pelo reconhecimento das células fúngicas por receptores expressos por células do sistema imunológico inato. Dentre esses receptores, o NLRP3 foi associado com o reconhecimento de fungos patogênicos em modelos experimentais, atuando em conjunto com o TLR2 e a dectina-1. O NLRP3 atua na formação de um complexo multiproteico denominado inflamassoma, o qual ativa a caspase-1, que é responsável pela produção das formas ativas de duas importantes citocinas inflamatórias: a IL-1? e a IL-18. Esse estudo teve por objetivo investigar o envolvimento do NLRP3 na ativação da resposta inflamatória de macrófagos e células dendríticas humanas (DCs) derivadas de monócitos em resposta ao Paracoccidioides brasiliensis (Pb), além de avaliar a participação do NLRP3 na indução da resposta imunológica adaptativa. Nossos resultados demonstraram que células de lesões de pacientes com PCM (mucosa oral ou linfonodos) apresentam produção de IL-1beta, IL-18 e IL-37 e que macrófagos dessas lesões são positivos para Caspase-1 e NLRP3. Também fomos capazes de demonstrar que o reconhecimento de células leveduriformes por DCs e macrófagos humanos leva à ativação do inflamassoma NLRP3 e consequente produção de IL-1 e IL-18. Esse reconhecimento envolve a participação de receptores de superfície (TLR2 e Dectina-1), sendo que a produção dessas citocinas é dependente da sinalização via dectina-1 e fosforilação da proteína Syk. Além disso, observamos que a ativação do inflamassoma NLRP3, após o reconhecimento do fungo, envolve como principais mecanismos a produção de ROS e o efluxo de K+. Nossos dados também demonstraram que o inflamassoma NLRP3 é essencial para a diferenciação de células Th17 e Th1 e que sua inibição leva à um aumento de células Th2 e Treg. Em conjunto nossos dados indicam que a ativação do NLRP3 desempenha um papel importante, tanto na indução de uma resposta inflamatória inicial, quanto no desenvolvimento de uma resposta adquirida que pode ser associada à resistência à infecção pelo P. brasiliensis
Abstract: Several studies have shown that the inflammatory response is crucial for the control of paracoccidioidomycosis (PCM). This inflammatory response is initiated by the recognition of fungal yeast cells by receptors expressed by cells of the innate immune system. Among these receptors, NLRP3 was associated with the recognition of pathogenic fungi in experimental models, working in conjunction with TLR2 and dectin-1. The NLRP3 acts forming a multiproteic complex called inflammasome, which activates caspase-1, and the production of the active forms of two important cytokines: IL-1? and IL-18. This study aimed to investigate the involvement of NLRP3 activation in the inflammatory response of macrophages and human dendritic cells (DCs) derived from monocytes, in response to Paracoccidioides brasiliensis (Pb), and to evaluate the participation of NLRP3 in the induction of the subsequent adaptive immune response. Our results demonstrated that cells of lesions from PCM patients (oral mucosa and lymph nodes) express IL-1beta, IL-18 and IL-37, and that macrophages in these lesions are positive for caspase-1 and NLRP3. We were also able to demonstrate that the recognition of Pb yeast cells by human macrophages and DCs leads to the NLRP3 inflammasome activation and production of IL-1 and IL-18. This recognition involves the participation of surface receptors (TLR2 and Dectin-1), and the production of these cytokines was dependent on signaling via dectin-1 and phosphorylation of Syk. In addition, we observed that the activation of the NLRP3 inflammasome, after recognition of the fungus, involves as main mechanisms the ROS production and the K+ efflux. Our data also demonstrate that the NLRP3 inflammasome are essential for the differentiation of Th1 and Th17 cells and its inhibition leads to an increased frequency of Th2 and Treg cells. Taken together our data indicated that activation of NLRP3 present an important role in both the induction of an initial inflammatory response, and in the development of an acquired immune response, which can be associated with the resistance to the P. brasiliensis infection
Mestrado
Ciencias Biomedicas
Mestra em Ciências Médicas