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Bracci, Laura, David F. Stroncek, Stefanie Slezak, Giulio C. Spagnoli i Maurizio Provenzano. "Comprehensive Analysis of CD8 T Cell Immune Response Specific for Two Novel HLA-A*0201 Restriced CMV pp65 Peptides." Blood 106, nr 11 (16.11.2005): 3928. http://dx.doi.org/10.1182/blood.v106.11.3928.3928.
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Abstract In immune compromised subjects such as patients undergoing bone marrow, organ transplantation or immunosuppressive therapies, Cytomegalovirus (CMV) infection is associated with significant morbidity until the individual’s immune system is completely reconstituted. One method of preventing CMV infection during immune suppression in transplant patients is represented by adoptive administration of CMV peptide-specific cytotoxic T lymphocytes (CTLs) from HLA-matched donors. Despite the strong immunogenicity demonstrated by specific HLA class I peptides, the peptide’s responsiveness varies among individuals. Therefore, it is important to identify additional epitopes for each HLA determinant of interest. In this study we report a comprehensive analysis of CD8 T cell-specific activity against two novel CMV pp65 HLA-A*0201 associated peptides in CMV-experienced HLA-A*0201 subjects. PBMCs from CMV seropositive HLA-A*0201 restricted healthy subjects were peptide-stimulated ex vivo and IFN-γ gene expression was analyzed by qrt-PCR. An IFN-γ ELISPOT assay was carried out on peptide-specific elicited CD8 T lymphocytes to confirm the qrt-PCR results. Tetrameric HLA/epitope complexes (tHLA) were used to track the levels of peptide-specific CD8 T cells responsiveness to cognate epitopes. In addition, in vitro peptide-specific expanded populations of CTLs were used in 51Cr release assay. Based on qrt-PCR results, four out of eight HLA-A*0201 peptides identified by computer algorithms were selected. Two are preaviously published peptides: pp65495–503 (NLVPMVATV) and pp65347–355 (ALFFFDIDL), while two are novel: pp65340–348 (RQYDPVAAL) and pp65310–318 (LMNGQQIFL). In spite the four peptides induced comparable mRNA IFN-γ transcript production, peptides pp65495–503, pp65340–348 and pp65310–318 induced a consistent and sustained IFN-γ protein release and specific killing, while the pp65347–355 failed to induce IFN-γ protein secretion and killing activity (if we exclude a positive IFN-γ protein release after 2-week in vitro induction in one of the donors tested). Comparative assays carried on the functional activity of the three peptides pp65495–503, pp65340–348 and pp65310–318 revealed no intrinsic differences in term of IFN-γ protein release and cytotoxic activity save for the CTL affinity to the HLA-A*0201/epitope complexes (pp65495–503 ~2.6% in nearly 100% of donors vs pp65340–348 ~0.67% or pp65310–318 ~0.77% in nearly one third of the donors after 2-week in vitro induction). The tHLA binding results could be possibly ascribed to differencies in the peptide avidity and stability for the HLA class I. Taken together, these results lead to the conclusion that different peptides can induce a variable levels of immune responses ranging between mere cytokine gene expression and effective cytotoxic activity. In addition, the two novel peptides selected here broaden the panel of potential reagents useful for adoptive immune therapy. Thus, in anticipation of a specific epitope-targeted immune intervention, the three HLA-A*0201 peptides described could be used in combination for adoptive transfer of epitope-specific T cells or epitope-specific vaccination.
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Möller, Carolina, i Frank Marí. "A vasopressin/oxytocin-related conopeptide with γ-carboxyglutamate at position 8". Biochemical Journal 404, nr 3 (29.05.2007): 413–19. http://dx.doi.org/10.1042/bj20061480.
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Vasopressins and oxytocins are homologous, ubiquitous and multifunctional peptides present in animals. Conopressins are vasopressin/oxytocin-related peptides that have been found in the venom of cone snails, a genus of marine predatory molluscs that envenom their prey with a complex mixture of neuroactive peptides. In the present paper, we report the purification and characterization of a unique conopressin isolated from the venom of Conus villepinii, a vermivorous cone snail species from the western Atlantic Ocean. This novel peptide, designated γ-conopressin-vil, has the sequence CLIQDCPγG* (γ is γ-carboxyglutamate and * is C-terminal amidation). The unique feature of this vasopressin/oxytocin-like peptide is that the eighth residue is γ-carboxyglutamate instead of a neutral or basic residue; therefore it could not be directly classified into either the vasopressin or the oxytocin peptide families. Nano-NMR spectroscopy of the peptide isolated directly from the cone snails revealed that the native γ-conopressin-vil undergoes structural changes in the presence of calcium. This suggests that the peptide binds calcium, and the calcium-binding process is mediated by the γ-carboxyglutamate residue. However, the negatively charged residues in the sequence of γ-conopressin-vil may mediate calcium binding by a novel mechanism not observed in other peptides of this family.
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Mujtaba, Mustafa. "Antiviral inducing properties of staphylococcal enterotoxin mimetic peptides (VAC9P.1065)". Journal of Immunology 194, nr 1_Supplement (1.05.2015): 145.5. http://dx.doi.org/10.4049/jimmunol.194.supp.145.5.
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Abstract Superantigens, like the staphylococcal enterotoxins, activate vast numbers of T-cells to produce large amounts of cytokines, including interferon-gamma (IFN-γ), and eventually cause these cells to undergo apoptosis. The objective of this research was to design mimetic peptides of staphylococcal enterotoxins that are not toxic to cells, but can produce antiviral activity in cells via production of IFN-γ. Based on the amino acid sequences of staphylococcal enterotoxins (SE) A, B, C, and toxic shock syndrome toxin, peptides were designed to mimic the antigenic sites of these superantigens. Whole protein superantigens (SEA) at concentrations ranging from 1.0 to 10.0ng/mL stimulated T-cell proliferation and induced IFN-γ production. Superantigen concentrations at or above 100ng/mL showed cellular toxicity. Of the eight mimetic peptides tested, SEA 3 was the only peptide that induced IFN-γ production, as determined by the IFN-γ ELISA kit, in HPBMC but did not induce cellular proliferation. SEA1, SEA2, and TSST peptides induced cellular proliferation but no IFN-γ stimulation. The peptides showed no toxicity directly on HeLa cells or HPBMC at 100 ug/mL or lower. Cell supernatant from the SEA3 peptide treated HPBMC also had antiviral activity against vesicular stomatitis virus. Thus, this study showed that mimetic peptides of superantigens could be developed that can induce T-cells to produce IFN-γ without the cellular toxicity associated with superantigens.
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Saini, Chaman, H. K. Prasad, Rajni Rani, A. Murtaza, Namita Misra, N. P. Shanker Narayan i Indira Nath. "Lsr2 of Mycobacterium leprae and Its Synthetic Peptides Elicit Restitution of T Cell Responses in Erythema Nodosum Leprosum and Reversal Reactions in Patients with Lepromatous Leprosy". Clinical and Vaccine Immunology 20, nr 5 (27.02.2013): 673–82. http://dx.doi.org/10.1128/cvi.00762-12.
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ABSTRACTThe Lsr2 protein ofMycobacterium lepraeand its synthetic peptides have been shown to elicit lymphoproliferation and gamma interferon (IFN-γ) release by peripheral blood mononuclear cells (PBMCs) of patients with lepromatous leprosy (M. Chaduvula, A. Murtaza, N. Misra, N. P. Narayan, V. Ramesh, H. K. Prasad, R. Rani, R. K. Chinnadurai, I. Nath, Infect. Immun. 80:742–752, 2012). PBMCs from 16 patients with lepromatous leprosy who were undergoing erythema nodosum leprosum (ENL) (type 2) and 5 patients with reversal reactions (RR) (type 1) were stimulated withM. leprae, recombinant Lsr2, and six end-to-end synthetic peptides (A through F) spanning the Lsr2 sequence. During the reaction all patients with ENL showed lymphoproliferation (stimulation index, >2) in response to peptides A and F, with other peptides eliciting responses in 75 to 88% of the subjects. In PBMC cultures, both lymphoproliferation and IFN-γ release for peptide E were significantly higher than for peptides B and C and recombinant Lsr2 (P< 0.05, Wilcoxon signed-rank test). Five patients with RR also showed enhanced lymphoproliferative responses and IFN-γ release in response to Lsr2,M. leprae, and peptide E. Six months postreaction, 14 patients with ENL continued to exhibit responses to Lsr2 and its peptides, with the highest responses being elicited by peptide E. However, 5 subjects showed no lymphoproliferation and had reduced IFN-γ release in response to Lsr2 peptides (P< 0.001, Kruskal-Wallis test) but responded to recombinant Lsr2. Six patients with ENL had HLA-A*68.01, which the STFPEITHI program showed to have high peptide-binding scores of 20 to 21 for peptides E, B, and C. Eleven patients had HLA-DRB1*1501 and HLA-DRB1*1502, which had high binding scores for peptides C and E. Thus, Lsr2 and its peptides are recognized in leprosy reactions during and well after the subsidence of clinical signs.
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Passero, Christopher J., Marcelo D. Carattino, Ossama B. Kashlan, Mike M. Myerburg, Rebecca P. Hughey i Thomas R. Kleyman. "Defining an inhibitory domain in the gamma subunit of the epithelial sodium channel". American Journal of Physiology-Renal Physiology 299, nr 4 (październik 2010): F854—F861. http://dx.doi.org/10.1152/ajprenal.00316.2010.
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Proteases activate the epithelial sodium channel (ENaC) by cleaving the large extracellular domains of the α- and γ-subunits and releasing peptides with inhibitory properties. Furin and prostasin activate mouse ENaC by cleaving the γ-subunit at sites flanking a 43 residue inhibitory tract (γE144-K186). To determine whether there is a minimal inhibitory region within this 43 residue tract, we generated serial deletions in the inhibitory tract of the γ-subunit in channels resistant to cleavage by furin and prostasin. We found that partial or complete deletion of a short segment in the γ-subunit, R158-N171, enhanced channel activity. Synthetic peptides overlapping this segment in the γ-subunit further identified a key 11-mer tract, R158-F168 (RFLNLIPLLVF), which inhibited wild-type ENaC expressed in Xenopus laevis oocytes, and endogenous channels in mpkCCD cells and human airway epithelia. Further studies with amino acid-substituted peptides defined residues that are required for inhibition in this key 11-mer tract. The presence of the native γ inhibitory tract in ENaC weakened the intrinsic binding constant of the 11-mer peptide inhibitor, suggesting that the γ inhibitory tract and the 11-mer peptide interact at overlapping sites within the channel.
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Huang, Xiao-Li, Zheng Fan, LuAnn Borowski i Charles R. Rinaldo. "Multiple T-Cell Responses to Human Immunodeficiency Virus Type 1 Are Enhanced by Dendritic Cells". Clinical and Vaccine Immunology 16, nr 10 (19.08.2009): 1504–16. http://dx.doi.org/10.1128/cvi.00104-09.
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ABSTRACT Human immunodeficiency virus type 1 (HIV-1)-specific T-cell reactivity has been related to protection from disease progression. Optimal T-cell reactivity to HIV-1 presumably requires antigen processing and presentation by professional antigen-presenting cells, particularly dendritic cells (DC). Here we examined whether multiple HIV-1-specific T-cell functions are enhanced by stimulation with HIV-1 peptide-loaded DC derived from HIV-1-infected subjects on antiretroviral therapy. We first found that mature DC increased the number of gamma interferon (IFN-γ)-producing T cells detected by enzyme-linked immunospot assay to overlapping 15-mer peptides of HIV-1 Gag and Nef, compared to stimulation with peptide-loaded, immature DC or to peptides without DC. IFN-γ production was lower in response to large pools of the Gag and Nef peptides, regardless of presentation by DC. We further observed that HIV-1 peptide-loaded, mature DC stimulated greater CD8+ and CD4+ T-cell proliferation than did the peptides without DC and that T-cell proliferation was lower in response to larger pools of the peptides. The lower T-cell IFN-γ and proliferation responses to the larger peptide pools were related to lower T-cell viability. Finally, the number of polyfunctional CD8+ and CD4+ T cells stimulated by HIV-1 peptide-loaded, mature DC, defined as positive by intracellular staining for more than one immune mediator (IFN-γ, interleukin 2, tumor necrosis factor alpha, macrophage inhibitory protein 1β, or CD107a), was greater than that stimulated by the peptides alone. These results indicate that DC can enhance multiple types of HIV-1-specific T-cell functions.
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Hirano, Naoto, Marcus O. Butler, Zhinan Xia, Seiji Kojima i Lee M. Nadler. "γ-Globin, a Tumor-Associated Antigen for Juvenile Myelomonocytic Leukemia (JMML): A Cell-Based Approach To Identify Tumor Antigenic Epitopes That Are Naturally Processed and Presented." Blood 104, nr 11 (16.11.2004): 3418. http://dx.doi.org/10.1182/blood.v104.11.3418.3418.
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Abstract Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder of early childhood. Although allogeneic stem cell transplantation can induce long-term remissions, relapse rates remain high, and innovative approaches are needed. Since donor lymphocyte infusion in JMML is efficacious, T cell mediated immunotherapy may be effective, and appropriate antigenic targets must be identified. One candidate tumor-associated antigen for the immunotherapy of JMML is γ-globin, which is expressed at high levels in most JMML patients. Most clonogenic JMML cells constitutively express this onco-fetal protein, which is not necessary for the normal erythropoesis of children and adults. To determine whether γ-globin can serve as a target for immunotherapy in JMML, we sought to determine whether γ-globin is naturally processed and presented by the HLA complex. Using conventional bioinformatic techniques and the T2 binding assay to predict candidate epitopes, we identified 4 γ-globin derived peptides (g031, g071, g105, and g106) that were predicted to bind to the HLA-A2 molecule in vitro. Since this strategy provides no evidence for which predicted epitopes are processed and presented by tumor cells in vivo, we employed a biochemical strategy to determine which peptides are naturally processed and presented. This step is critical in certifying that a candidate peptide epitope is an appropriate target for immunotherapy treatments. Using our K562-derived artificial APC (aAPC), an APC that expresses A2 and no other HLA allele, we introduced the EGFP-γ-globin fusion gene. We then acid stripped peptides directly from the surface of one billion aAPC/EGFP-γ-globin cells without subjecting the cells to detergent mediated lysis. Peptides less than 5 kDa in size were fractionated by reverse phased HPLC analysis and analyzed by mass spectrometry. We identified two mass spectrometry peaks which corresponded to γ-globin derived peptides, g031 and g105. Of these, the identity of one peak, g105, was successfully confirmed by peptide sequencing, providing strong evidence that g105 is naturally processed and presented by aAPC/EGFP-γ-globin cells. Next, to confirm that g105 is processed and presented by primary JMML cells, we generated γ-globin specific CD8+ cytotoxic T cells (CTL) from A2 positive healthy donors using synthetic g105 peptide. γ-Globin specific CTL were able to specifically cytolyze A2+ γ-globin+ JMML cells but not A2+ γ-globin- JMML cells. Specific cytotoxicity was blocked by anti-A2 mAb but not isotype control. These results show for the first time that the γ-globin derived peptide, g105, can serve as a target epitope for the CTL directed immunotherapy of JMML. Furthermore, these results illustrate an innovative aAPC based strategy that can identify the antigenic peptide epitopes of putative tumor associated antigens that are naturally processed by tumor cells, presented via HLA class I, and can serve as targets for effective anti-cancer immunotherapy.
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BECERRIL, Baltazar, Miguel CORONA, Fredy I. V. CORONAS, Fernando ZAMUDIO, Emma S. CALDERONARANDA, Paul L. FLETCHER, Brian M. MARTIN i Lourival D. POSSANI. "Toxic peptides and genes encoding toxin γ of the Brazilian scorpions Tityus bahiensis and Tityus stigmurus". Biochemical Journal 313, nr 3 (1.02.1996): 753–60. http://dx.doi.org/10.1042/bj3130753.
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Seven toxic peptides from the venom of Tityus bahiensis and Tityus stigmurus were isolated and sequenced, five of them to completion. The most abundant peptide from each of these two species of scorpion was 95% identical with that of toxin γ from the venom of Tityus serrulatus. They were consequently named γ-b and γ-st respectively. The genes encoding these new γ-like peptides were cloned and sequenced by utilizing oligonucleotides synthesized according to known cDNA sequences of toxin γ, and amplified by PCR on templates of DNA purified from both T. bahiensis and T. stigmurus. They contain an intron of approx. 470 bp. Possible mechanisms of processing and expressing these peptides are discussed, in view of the fact that glycine is the first residue of the N-terminal sequence of T. stigmurus, whereas lysine is the residue at position 1 of toxin γ from T. serrulatus and T. bahiensis. In addition, chemical characterization of the less abundant toxic peptides showed the presence of at least four distinct families of peptides in all three species of the genus Tityus studied. There is a large degree of similarity among peptides from different venoms of the same family. By using specific horse and rabbit antisera, the venoms of T. bahiensis, T. serrulatus and T. stigmurus were compared. They showed an extended degree of cross-reactivity. Thus these three species of scorpion have similar toxic components, the genes of which are similarly organized, processed and expressed.
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Zeng, Yi, Michael W. Graner, Sylvia Thompson, Marilyn Marron i Emmanuel Katsanis. "Induction of BCR-ABL–specific immunity following vaccination with chaperone-rich cell lysates derived from BCR-ABL+ tumor cells". Blood 105, nr 5 (1.03.2005): 2016–22. http://dx.doi.org/10.1182/blood-2004-05-1915.
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AbstractWe have previously reported that chaperonerich cell lysates (CRCL) derived from the BCR-ABL+ 12B1 leukemia activate dendritic cells (DCs) and stimulate leukemia-specific immune responses. Because CRCL contain a variety of heat shock/chaperone proteins, we theorized that CRCL obtained from BCR-ABL+ leukemias are likely to chaperone BCR-ABL–derived fusion peptides and that DCs pulsed with 12B1 CRCL could cross-present BCR-ABL fusion peptides to T cells. We found that splenocytes from mice vaccinated with BCR-ABL+ leukemia-derived CRCL secreted interferon-γ (IFN-γ) when restimulated with a BCR-ABL peptide, GFKQSSKAL, indicating that BCR-ABL peptides are chaperoned by leukemia-derived CRCL. We next eluted peptides from 12B1 leukemia-derived CRCL and used high-pressure liquid chromatography (HPLC) fractions to restimulate splenocytes harvested from mice vaccinated with DC/GFKQSSKAL or DC/12B1 CRCL. We found that the same peptide fractions derived from 12B1 CRCL and from “refractionated” GFKQSSKAL stimulated IFN-γ production, suggesting the presence of BCR-ABL peptides in the peptide repertoire of 12B1 CRCL. We also demonstrated that immunization with DCs loaded with leukemia-derived CRCL induced BCR-ABL–specific cytotoxic T lymphocytes (CTLs) in vivo. Moreover, mice immunized with DCs pulsed with 12B1-derived CRCL had superior survival (60%) when compared with those immunized with DCs pulsed with BCR-ABL peptide (20%), indicating that CRCL vaccines provide additional immune stimulus over and above individual peptide vaccination.
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Staska, Lauren M., Christopher J. Davies, Wendy C. Brown, Travis C. McGuire, Carlos E. Suarez, Joo Youn Park, Bruce A. Mathison, Jeffrey R. Abbott i Timothy V. Baszler. "Identification of Vaccine Candidate Peptides in the NcSRS2 Surface Protein of Neospora caninum by Using CD4+ Cytotoxic T Lymphocytes and Gamma Interferon-Secreting T Lymphocytes of Infected Holstein Cattle". Infection and Immunity 73, nr 3 (marzec 2005): 1321–29. http://dx.doi.org/10.1128/iai.73.3.1321-1329.2005.
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ABSTRACT Previously, our laboratory showed that Holstein cattle experimentally infected with Neospora caninum develop parasite-specific CD4+ cytotoxic T lymphocytes (CTL) that lyse infected, autologous target cells through a perforin-granzyme pathway. To identify specific parasite antigens inducing bovine CTL and helper T-lymphocyte responses for vaccine development against bovine neosporosis, the tachyzoite major surface proteins NcSAG1 and NcSRS2 were targeted. In whole tachyzoite antigen-expanded bovine T-lymphocyte lines, recombinant NcSRS2 induced potent memory CD4+- and CD8+-T-lymphocyte activation, as indicated by proliferation and gamma interferon (IFN-γ) secretion, while recombinant NcSAG1 induced a minimal memory response. Subsequently, T-lymphocyte epitope-bearing peptides of NcSRS2 were mapped by using overlapping peptides covering the entire NcSRS2 sequence. Four experimentally infected cattle with six different major histocompatibility complex (MHC) class II haplotypes were the source of immune cells used to identify NcSRS2 peptides presented by Holstein MHC haplotypes. NcSRS2 peptides were mapped by using IFN-γ secretion by rNcSRS2-stimulated, short-term T-lymphocyte cell lines, IFN-γ enzyme-linked immunospot (ELISPOT) assay with peripheral blood mononuclear cells, and 51Cr release cytotoxicity assay of rNcSRS2-stimulated effector cells. Four N. caninum-infected Holstein cattle developed NcSRS2 peptide-specific T lymphocytes detected ex vivo in peripheral blood by IFN-γ ELISPOT and in vitro by measuring T-lymphocyte IFN-γ production and cytotoxicity. An immunodominant region of NcSRS2 spanning amino acids 133 to 155 was recognized by CD4+ T lymphocytes from the four cattle. These findings support investigation of subunit N. caninum vaccines incorporating NcSRS2 gene sequences or peptides for induction of NcSRS2 peptide-specific CTL and IFN-γ-secreting T lymphocytes in cattle with varied MHC genotypes.
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Rudakova, A. A., M. A. Baryshnikova, Z. A. Sokolova, O. S. Burova, E. N. Kosobokova i V. S. Kosorukov. "EVALUATION OF IMMUNOGENICITY OF SYNTHETIC NEOANTIGEN PEPTIDES FOR THE MELANOMA VACCINE MODEL". Russian Journal of Biotherapy 20, nr 2 (14.07.2021): 61–68. http://dx.doi.org/10.17650/1726-9784-2021-20-2-61-68.
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Introduction. Immunotherapy based on the usage of mutant tumor neoantigens to activate the antitumor immune response is one of the most promising approaches to cancer treatment.Purpose. Evaluation of individual immunogenicity of synthetic neoantigen peptides for the B16-F10 melanoma vaccine model.Materials and methods. We studied 32 synthetic neoantigen peptides with a length of 25–27 amino acids, which were previously selected as potentially immunogenic by bioinformatic analysis of B16-F10 melanoma sequencing data and healthy tissues of C57Bl/6J mice. Groups of C57Bl/6J mice were immunized four times at weekly intervals with each individual peptide in combination with the adjuvant Poly(I:C), one of the groups was immunized only with Poly(I:C), and the control group was not immunized with anything. The immunogenicity of peptides was assessed by the production of interferon γ in splenocytes using the ELISpot method and by the level of serum cytokines Th1/Th2 using the ELISA method in immunized mice and in animals in the control group.Results. Of the 32 peptides studied, 25 caused an increase in the number of interferon-γ-producing spleen cells in previously immunized mice, but 8 of these peptides caused a non-specific increase in the production of interferon γ by splenocytes in non-immunized animals. It was found that out of 32 peptides, only 11 caused an increase in the level of serum cytokines interferon γ and interleukin 4, which are responsible for the development of the immune response along the Th1 and Th2 pathways. But only 7 peptides affected an increase in the number of interferon-γ-producing splenocytes and an enhance of cytokines interferon γ and interleukin 4 levels.Conclusion. Thus, the immunogenicity of 32 synthetic neoantigen peptides was evaluated, and 7 peptides were shown to activate the cellular immune response.
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Geluk, Annemieke, Jolien J. van der Ploeg-van Schip, Krista E. van Meijgaarden, Susanna Commandeur, Jan W. Drijfhout, Willemien E. Benckhuijsen, Kees L. M. C. Franken, Bernard Naafs i Tom H. M. Ottenhoff. "Enhancing Sensitivity of Detection of Immune Responses to Mycobacterium leprae Peptides in Whole-Blood Assays". Clinical and Vaccine Immunology 17, nr 6 (28.04.2010): 993–1004. http://dx.doi.org/10.1128/cvi.00046-10.
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ABSTRACT Although worldwide leprosy prevalence has been reduced considerably following multidrug therapy, new case detection rates remain relatively stable, suggesting that transmission of infection still continues. This calls for new efforts, among which is development of assays that can identify subclinical/early-stage Mycobacterium leprae-infected subjects, a likely source of transmission. Areas in which leprosy is endemic often lack sophisticated laboratories, necessitating development of field-friendly immunodiagnostic tests for leprosy, like short-term whole-blood assays (WBA). In classical, peripheral blood mononuclear cell (PBMC)-based gamma interferon (IFN-γ) release assays, M. leprae peptides have been shown to discriminate in a more specific fashion than M. leprae proteins between M. leprae-exposed contacts and patients as opposed to healthy controls from the same area of endemicity. However, peptides induced significantly lower levels of IFN-γ than did proteins, particularly when whole blood was used. Therefore, possibilities of specifically enhancing IFN-γ production in response to M. leprae peptides in 24-h WBA were sought by addition of various cytokines and antibodies or by mannosylation of peptides. In addition, other cytokines and chemokines were analyzed as potential biomarkers in WBA. We found that only interleukin 12 (IL-12), not other costimulants, increased IFN-γ production in WBA while maintaining M. leprae peptide specificity, as evidenced by lack of increase of IFN-γ in control samples stimulated with IL-12 alone. The IL-12-induced increase in IFN-γ was mainly mediated by CD4+ T cells that did not produce IL-2 or tumor necrosis factor (TNF). Mannosylation further allowed the use of 100-fold-less peptide. Although not statistically significantly, macrophage inflammatory protein 1β (MIP-1β) and macrophage c protein 1 (MCP-1) levels specific for M. leprae peptide tended to be increased by IL-12. IP-10 production was also found to be a useful marker of M. leprae peptide responses, but its production was enhanced by IL-12 nonspecifically. We conclude that IFN-γ-based WBA combined with IL-12 represents a more sensitive and robust assay for measuring reactivity to M. leprae peptides.
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Tamm, Lukas K., i Xing Han. "Viral Fusion Peptides: A Tool Set to Disrupt and Connect Biological Membranes". Bioscience Reports 20, nr 6 (1.12.2000): 501–18. http://dx.doi.org/10.1023/a:1010406920417.
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The structure and function of viral fusion peptides are reviewed. The fusion peptides of influenza virus hemagglutinin and human immunodeficiency virus are used as paradigms. Fusion peptides associated with lipid bilayers are conformationally polymorphic. Current evidence suggests that the fusion-promoting state is the obliquely inserted α-helix. Fusion peptides also have a tendency to self-associate into γ-sheets at membrane surfaces. Although the conformational conversion between α- and γ-states is reversible under controlled conditions, its physiological relevance is not yet known. The energetics of peptide insertion and self-association could be measured recently using more soluble “second generation” fusion peptides. Fusion peptides have been reported to change membrane curvature and the state of hydration of membrane surfaces. The combined results are built into a model for the mechanism by which fusion peptides are proposed to assist in biological membrane fusion.
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Bandyopadhyay, Anupam, i Hosahudya N. Gopi. "Hybrid Peptides: Direct Transformation of α/α, β-Unsaturated γ-Hybrid Peptides to α/γ-Hybrid Peptide 12-Helices". Organic Letters 14, nr 11 (18.05.2012): 2770–73. http://dx.doi.org/10.1021/ol300987d.
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Diós, Ádám, Rita Elek, Ildikó Szabó, Szilvia Horváth, Judit Gyimesi, Róbert Király, Katharina Werkstetter, Sibylle Koletzko, László Fésüs i Ilma R. Korponay-Szabó. "Gamma-gliadin specific celiac disease antibodies recognize p31-43 and p57-68 alpha gliadin peptides in deamidation related manner as a result of cross-reaction". Amino Acids 53, nr 7 (31.05.2021): 1051–63. http://dx.doi.org/10.1007/s00726-021-03006-7.
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AbstractCeliac disease (CeD) is a T-cell-dependent enteropathy with autoimmune features where tissue transglutaminase (TG2)-mediated posttranslational modification of gliadin peptides has a decisive role in the pathomechanism. The humoral immune response is reported to target mainly TG2-deamidated γ-gliadin peptides. However, α-gliadin peptides, like p57-68, playing a crucial role in the T-cell response, and p31-43, a major trigger of innate responses, also contain B-cell gliadin epitopes and γ-gliadin like motifs. We aimed to identify if there are anti-gliadin-specific antibodies in CeD patients targeting the p31-43 and p57-68 peptides and to examine whether deamidation of these peptides could increase their antigenicity. We explored TG2-mediated deamidation of the p31-43 and p57-68 peptides, and investigated serum antibody reactivity toward the native and deamidated α and γ-gliadin peptides in children with confirmed CeD and in prospectively followed infants at increased risk for developing CeD. We affinity-purified antibody populations utilizing different single peptide gliadin antigens and tested their binding preferences for cross-reactivity in real-time interaction assays based on bio-layer interferometry. Our results demonstrate that there is serum reactivity toward p31-43 and p57-68 peptides, which is due to cross-reactive γ-gliadin specific antibodies. These γ-gliadin specific antibodies represent the first appearing antibody population in infancy and they dominate the serum reactivity of CeD patients even later on and without preference for deamidation. However, for the homologous epitope sequences in α-gliadins shorter than the core QPEQPFP heptapeptide, deamidation facilitates antibody recognition. These findings reveal the presence of cross-reactive antibodies in CeD patients recognizing the disease-relevant α-gliadins.
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He, Wenjiang, Xiaoling Huang, Abulimiti Kelimu, Wenzhi Li i Chun Cui. "Streamlined Efficient Synthesis and Antioxidant Activity of γ-[Glutamyl](n≥1)-tryptophan Peptides by Glutaminase from Bacillus amyloliquefaciens". Molecules 28, nr 13 (23.06.2023): 4944. http://dx.doi.org/10.3390/molecules28134944.
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As a group of naturally occurring peptides in various foods, γ-glutamyl peptides possess a unique Kokumi taste and health benefits. However, few studies have focused on the functionality of γ-glutamyl peptides. In this study, the γ-[glutamyl] (n=1, 2, 3)-tryptophan peptides were synthesized from a solution of glutamine (Gln) and tryptophan (Trp) employing L-glutaminase from Bacillus amyloliquefaciens. Four different γ-glutamyl peptides were identified from the reaction mixture by UPLC-Q-TOF-MS/MS. Under optimal conditions of pH 10, 37 °C, 3 h, 0.1 mol/L Gln: 0.1 mol/L Trp = 1:3, and glutaminase at 0.1% (m/v), the yields of γ-l-glutamyl-l-tryptophan (γ-EW), γ-l-glutamyl-γ-l-glutamyl-l-tryptophan (γ-EEW) and γ-l-glutamyl-γ-l-glutamyl-γ-l-glutamyl-l-tryptophan (γ-EEEW) were 51.02%, 26.12% and 1.91% respectively. The antioxidant properties of the reaction mixture and the two peptides (γ-EW, γ-EEW) identified from the reaction media were further compared. Results showed that γ-EW exhibited the highest DPPH•, ABTS•+ and O2•−-scavenging activity (EC50 = 0.2999 mg/mL, 67.6597 μg/mL and 5.99 mg/mL, respectively) and reducing power (EC50 = 4.61 mg/mL), while γ-EEW demonstrated the highest iron-chelating activity (76.22%). Thus, the synthesized mixture may be used as a potential source of antioxidant peptides for food and nutraceutical applications.
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Mustafa, Ghulam, Hafiza Salaha Mahrosh, Mahwish Salman, Sumaira Sharif, Raheela Jabeen, Tanveer Majeed i Hafsah Tahir. "Identification of Peptides as Novel Inhibitors to Target IFN-γ, IL-3, and TNF-α in Systemic Lupus Erythematosus". BioMed Research International 2021 (13.11.2021): 1–11. http://dx.doi.org/10.1155/2021/1124055.
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Autoimmune disorder is a chronic immune imbalance which is developed through a series of pathways. The defect in B cells, T cells, and lack of self-tolerance has been greatly associated with the onset of many types of autoimmune complications including rheumatoid arthritis, systemic lupus erythematosus (SLE), multiple sclerosis, and chronic inflammatory demyelinating polyneuropathy. The SLE is an autoimmune disease with a common type of lupus that causes tissue and organ damage due to the wide spread of inflammation. In the current study, twenty anti-inflammatory peptides derived from plant and animal sources were docked as ligands or peptides counter to proinflammatory cytokines. Interferon gamma (IFN-γ), interleukin 3 (IL-3), and tumor necrosis factor alpha (TNF-α) were targeted in this study as these are involved in the pathogenesis of SLE in many clinical studies. Two docking approaches (i.e., protein-ligand docking and peptide-protein docking) were employed in this study using Molecular Operating Environment (MOE) software and HADDOCK web server, respectively. Amongst docked twenty peptides, the peptide DEDTQAMMPFR with S -score of -11.3018 and HADDOCK score of − 10.3 ± 2.5 kcal/mol showed the best binding interactions and energy validation with active amino acids of IFN-γ protein in both docking approaches. Depending upon these results, this peptide could be used as a potential drug candidate to target IFN-γ, IL-3, and TNF-α proteins to control inflammatory events. Other peptides (i.e., QEPQESQQ and FRDEHKK) also revealed good binding affinity with IFN-γ with S -scores of -10.98 and -10.55, respectively. Similarly, the peptides KHDRGDEF, FRDEHKK, and QEPQESQQ showed best binding interactions with IL-3 with S -scores of -8.81, -8.64, and -8.17, respectively.
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Chaitra, M. G., M. S. Shaila i R. Nayak. "Evaluation of T-cell responses to peptides with MHC class I-binding motifs derived from PE_PGRS 33 protein of Mycobacterium tuberculosis". Journal of Medical Microbiology 56, nr 4 (1.04.2007): 466–74. http://dx.doi.org/10.1099/jmm.0.46928-0.
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The PE and PPE proteins of Mycobacterium tuberculosis form a source of antigenic variation among different strains of M. tuberculosis. One of the PE_PGRS proteins, Rv1818c, plays a role in the pathogenesis of mycobacterial infection and specifically influences host-cell responses to tuberculosis infection. Although little is known about these two classes of protein, an immunoinformatics approach has indicated the possibility of their participation in eliciting a major histocompatibility complex (MHC) class I-mediated immune response against tuberculosis, as peptides derived from Rv1818c are predicted to bind to MHC class I molecules with high affinity. In the present work, a DNA vaccine was constructed encoding the full-length Rv1818c protein of M. tuberculosis and its immunogenicity was analysed in BALB/c mice. Immunization with Rv1818c DNA induced a strong CD8+ cytotoxic lymphocyte and Th1-type response, with high levels of gamma interferon (IFN-γ) and low levels of interleukin-4. Two nonameric peptides (Peptide6–14 and Peptide385–393) from Rv1818c were identified by their ability to induce the production of IFN-γ by CD8+ T cells in mice immunized with Rv1818c DNA. An epitope-specific response was demonstrated by the lysis of peptide-pulsed antigen-presenting cells, release of cytotoxic granules and IFN-γ production. These peptides bound with high affinity to MHC H-2Kd and showed low dissociation rates of peptide–MHC complexes. These results could form the basis for testing the identified T-cell epitopes of PE_PGRS proteins in the induction of protective immunity against M. tuberculosis challenge in the mouse model.
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Kalantar, K., Z. Farzaneh, M. Eshkevar Vakili, M. H. Karimi, M. Asadi, S. Khosropanah i M. Doroudchi. "T cell responses to an HLA-A2-restricted adipophilin peptide correlate with BMI in patients with atherosclerosis". Physiology International 107, nr 2 (czerwiec 2020): 280–93. http://dx.doi.org/10.1556/2060.2020.00023.
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AbstractIntroductionAtherosclerosis is an inflammatory disease causing a vast array of cardiovascular diseases. Adipophilin has been reported to be highly expressed in atherosclerotic lesions. This study investigated the possible existence of auto-reactive T cells against an HLA-A02-restricted adipophilin-derived peptide as well as peptides from Epstein-barr virus (EBV), Cytomegalovirus (CMV) and influenza (Flu) virus in patients with atherosclerosis.MethodsHLA-A02 expression on peripheral blood mononuclear cells (PBMCs) was examined by flow cytometry. PBMCs from HLA-A02 individuals were stimulated with adipophilin, CMV, EBV, and Flu peptides at a concentration of 10 µM. Interferon (IFN)-γ production was evaluated in the culture supernatant using a commercial ELISA test.ResultsThe levels of IFN-γ production against an HLA-A02-restricted adipophilin peptide and peptides from CMV, EBV, and Flu revealed no statistically significant differences between patients and healthy controls. However, we found a positive correlation between IFN-γ production against adipophilin and Body mass index (BMI) of patients (R = 0.8, P = 0.003), whereas no significant correlation was found in healthy controls (R = −0.267, P = 0.378). No correlation between BMI and IFN-γ production against CMV, EBV, or Flu peptides was found.DiscussionAtherosclerotic patients with higher BMIs might have greater numbers of T cells against adipophilin that is highly expressed in atherosclerotic plaques. Therefore, autoimmune reactions may have a greater role in the development of atherosclerosis in individuals with higher BMI.
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Heres, Alejandro, Qian Li, Fidel Toldrá, René Lametsch i Leticia Mora. "Comparative Quantitation of Kokumi γ-Glutamyl Peptides in Spanish Dry-Cured Ham under Salt-Reduced Production". Foods 12, nr 14 (24.07.2023): 2814. http://dx.doi.org/10.3390/foods12142814.
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Salting is a crucial step during the production of dry-cured ham and it is not well known whether it has an impact on the generation of taste-active peptides. The present study focused on the quantitation of kokumi γ-glutamyl peptides in low-salted Spanish dry-cured hams with 12 months of processing. By using mass spectrometry, peptides were quantitated from samples obtained after ethanolic deproteinization-based and non-ethanolic deproteinization-based extraction methods. Peptides γ-EA, γ-EE, and γ-EL registered mean values of 0.31, 2.75, and 11.35 µg/g of dry-cured ham, respectively, with no differences observed between both extraction protocols. However, γ-EF, γ-EM, γ-EV, γ-EW, γ-EY, and γ-EVG presented significantly (p < 0.05) higher concentrations in the ethanolic deproteinized samples showing values of 5.58, 4.13, 13.90, 0.77, 3.71, and 0.11 µg/g of dry-cured ham, respectively. These outcomes reflect the importance of protocols for the extraction of peptides to achieve the most feasible results. In addition, potential precursors for the formation of γ-glutamyl peptides are generated during dry-curing under salt restriction. The kokumi activity of these γ-glutamyl peptides could enhance the sensory attributes countering the taste deficiencies caused by the salt restriction.
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Adibzadeh Sereshgi, Mohammad Mehdi, Sahar Salimi i Hassan Noorbazargan. "AK2 Antibacterial Synthetic Peptide Can Potentiate Macrophage Responses". ImmunoRegulation 4, nr 2 (1.01.2022): 73–82. http://dx.doi.org/10.32598/immunoregulation.4.2.1.
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Background: Emphasis on substitutional medications with the elevated bacterial resistance to current antibiotics is pivotal. We evaluated the antibacterial effect of AK2 by Minimum Bactericidal Concentration (MBC) and Minimum inhibitory Concentration (MIC) and its impact on macrophage responses in 17 strains of pathogenic bacteria. The gene expression of macrophage’s cytokines was evaluated. Accordingly, the bioinformatic assessment predicted this peptide’s physicochemical characteristics, behavior, and structures. The present study aimed to assess the antibacterial effect of AK2 peptides on Macrophage responses. Materials and Methods: Cytotoxicity level was assessed by MTT assay on the HeLa cell line. The hemolytic activity of peptides on red blood cells was evaluated. The Griess assay was performed to assess the amount of macrophage nitric oxide production. The real-time PCR method measured the iNOS, IFN-γ, and TNF-α gene expression in isolated macrophages. Results: Peptide concentrations (13-60 µg/mL) were observed as the MBC and MIC value results for various bacteria. No remarkable cytotoxicity was observed at 30 and 60 µg/ml concentrations after 24h. iNOS, IFN-γ, and TNF-α gene expression were upregulated. There was also a higher secretion of nitric oxide in 48 hour-culture of the cell line with peptide. Great antibacterial activity was observed in some bacterial strains, particularly B. melitensis. Conclusion: AK2 peptides display suitable antibacterial activity with negligible toxicity for host cells. This peptide could also stimulate macrophage responses through nitric oxide production and gene expression in proinflammatory cytokines.
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Kothari, Abhishek, M. Khurram N. Qureshi, Elizabeth M. Beck i Martin D. Smith. "Bend-ribbon forming γ-peptides". Chem. Commun., nr 27 (2007): 2814–16. http://dx.doi.org/10.1039/b706528k.
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Slezina, Marina P., Ekaterina A. Istomina, Ekaterina V. Kulakovskaya, Tatyana V. Korostyleva i Tatyana I. Odintsova. "The γ-Core Motif Peptides of AMPs from Grasses Display Inhibitory Activity against Human and Plant Pathogens". International Journal of Molecular Sciences 23, nr 15 (29.07.2022): 8383. http://dx.doi.org/10.3390/ijms23158383.
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Antimicrobial peptides (AMPs) constitute an essential part of the plant immune system. They are regarded as alternatives to conventional antibiotics and pesticides. In this study, we have identified the γ-core motifs, which are associated with antimicrobial activity, in 18 AMPs from grasses and assayed their antimicrobial properties against nine pathogens, including yeasts affecting humans, as well as plant pathogenic bacteria and fungi. All the tested peptides displayed antimicrobial properties. We discovered a number of short AMP-derived peptides with high antimicrobial activity both against human and plant pathogens. For the first time, antimicrobial activity was revealed in the peptides designed from the 4-Cys-containing defensin-like peptides, whose role in plant immunity has remained unknown, as well as the knottin-like peptide and the C-terminal prodomain of the thionin, which points to the direct involvement of these peptides in defense mechanisms. Studies of the mode of action of the eight most active γ-core motif peptides on yeast cells using staining with propidium iodide showed that all of them induced membrane permeabilization leading to cell lysis. In addition to identification of the antimicrobial determinants in plant AMPs, this work provides short candidate peptide molecules for the development of novel drugs effective against opportunistic fungal infections and biopesticides to control plant pathogens.
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Liu, Lei, Li Ding, Matteo Rovere, Michael S. Wolfe i Dennis J. Selkoe. "A cellular complex of BACE1 and γ-secretase sequentially generates Aβ from its full-length precursor". Journal of Cell Biology 218, nr 2 (9.01.2019): 644–63. http://dx.doi.org/10.1083/jcb.201806205.
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Intramembrane proteolysis of transmembrane substrates by the presenilin–γ-secretase complex is preceded and regulated by shedding of the substrate’s ectodomain by α- or β-secretase. We asked whether β- and γ-secretases interact to mediate efficient sequential processing of APP, generating the amyloid β (Aβ) peptides that initiate Alzheimer’s disease. We describe a hitherto unrecognized multiprotease complex containing active β- and γ-secretases. BACE1 coimmunoprecipitated and cofractionated with γ-secretase in cultured cells and in mouse and human brain. An endogenous high molecular weight (HMW) complex (∼5 MD) containing β- and γ-secretases and holo-APP was catalytically active in vitro and generated a full array of Aβ peptides, with physiological Aβ42/40 ratios. The isolated complex responded properly to γ-secretase modulators. Alzheimer’s-causing mutations in presenilin altered the Aβ42/40 peptide ratio generated by the HMW β/γ-secretase complex indistinguishably from that observed in whole cells. Thus, Aβ is generated from holo-APP by a BACE1–γ-secretase complex that provides sequential, efficient RIP processing of full-length substrates to final products.
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Illa, Ona, José-Antonio Olivares, Nerea Gaztelumendi, Laura Martínez-Castro, Jimena Ospina, María-Ángeles Abengozar, Giuseppe Sciortino i in. "Chiral Cyclobutane-Containing Cell-Penetrating Peptides as Selective Vectors for Anti-Leishmania Drug Delivery Systems". International Journal of Molecular Sciences 21, nr 20 (12.10.2020): 7502. http://dx.doi.org/10.3390/ijms21207502.
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Two series of new hybrid γ/γ-peptides, γ-CC and γ-CT, formed by (1S,2R)-3-amino-2,2,dimethylcyclobutane-1-carboxylic acid joined in alternation to a Nα-functionalized cis- or trans-γ-amino-l-proline derivative, respectively, have been synthesized and evaluated as cell penetrating peptides (CPP) and as selective vectors for anti-Leishmania drug delivery systems (DDS). They lacked cytotoxicity on the tumoral human cell line HeLa with a moderate cell-uptake on these cells. In contrast, both γ-CC and γ-CT tetradecamers were microbicidal on the protozoan parasite Leishmania beyond 25 μM, with significant intracellular accumulation. They were conjugated to fluorescent doxorubicin (Dox) as a standard drug showing toxicity beyond 1 μM, while free Dox was not toxic. Intracellular accumulation was 2.5 higher than with Dox-TAT conjugate (TAT = transactivator of transcription, taken as a standard CPP). The conformational structure of the conjugates was approached both by circular dichroism spectroscopy and molecular dynamics simulations. Altogether, computational calculations predict that the drug-γ-peptide conjugates adopt conformations that bury the Dox moiety into a cavity of the folded peptide, while the positively charged guanidinium groups face the solvent. The favorable charge/hydrophobicity balance in these CPP improves the solubility of Dox in aqueous media, as well as translocation across cell membranes, making them promising candidates for DDS.
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DeLucia, Diana, Tiffany Pariva, Roland Strong, Owen Witte i John Lee. "148 Identification of prostate-restricted epithelial antigens for transgenic T cell adoptive therapy against prostate cancer". Journal for ImmunoTherapy of Cancer 8, Suppl 3 (listopad 2020): A161. http://dx.doi.org/10.1136/jitc-2020-sitc2020.0148.
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BackgroundIn advanced prostate cancer (PCa), progression to castration-resistant PCa (CRPC) is inevitable and novel therapies for CRPC are needed. Adoptive transfer of T cells targeting tumor antigens is a promising approach in the cancer field. Unfortunately, identifying antigens expressed exclusively in prostate tumor cells has been challenging. Since the prostate is not an essential organ, we alternatively selected prostate-restricted epithelial antigens (PREAs) expressed in both malignant and normal prostate tissue for transgenic T cell studies.MethodsRNA-seq data sets identifying genes enriched in PCa were cross-referenced with the NIH Genotype-Expression database to identify PREAs. Using a novel molecular immunology approach, select PREAs and major histocompatibility complex class I (MHC-I) molecules were co-expressed in HEK293F cells, from which MHC–peptide complexes were efficiently isolated. Peptides were eluted and sequenced by mass spectrometry. Peptide–MHC binding was validated with a T2 stabilization assay and peptide immunodominance was determined using an interferon-γ (IFN-γ) ELISpot assay following stimulation of healthy HLA-A2+ peripheral blood mononuclear cells (PBMC) with peptide pools. Following peptide stimulation, CD8+ T cells with peptide-specific T cell receptors (TCR) were enriched by peptide–MHC-I dextramer labeling and fluorescence activated cell sorting for single cell TCR α/β chain sequencing.ResultsWe identified 11 A2+ peptides (8 previously unpublished) from prostatic acid phosphatase (ACPP), solute carrier family 45 member 3 (SLC45A3), and NK3 homeobox 1 (NKX3.1) that bound to HLA-A2 with varying affinities. Extended culture stimulation of PBMC with peptide pools from each PREA, compared to the standard overnight culture, revealed a greater number of IFN-γ producing cells overall and a greater breadth of response across all the peptides. Antigen specific CD8+ T cells were detectable at low frequencies in both male and female healthy PBMC for 7 of the 11 peptides. Dextramer-sorted antigen-specific cells were used for single-cell paired TCR αβ sequencing and transgenic T cell development.ConclusionsThrough this work we identified HLA-A2-presented antigenic peptides from the PREAs ACPP, SLC45A3, and NKX3.1 that can induce the expansion of IFN-γ producing CD8+ T cells. Through peptide–MHC-I dextramer labeling, we isolated PREA-specific CD8+ T cells and characterized TCR αβ sequences with potential anti-tumor functionality. Our results highlight a rapid and directed platform for the development of MHC-I-restricted transgenic CD8+ T cells targeting lineage-specific proteins expressed in prostate epithelia for adoptive therapy of advanced PCa.
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Morozov, Giora, Huaying Zhao, Michael Mage, Lisa Boyd, Ramesh Venna, Michael Norcross, Curtis McMurtrey i in. "Direct interaction of recombinant TAPBPR with MHC-I molecules: stabilization of peptide-free MHC-I promotes high affinity peptide loading (APP5P.102)". Journal of Immunology 194, nr 1_Supplement (1.05.2015): 183.4. http://dx.doi.org/10.4049/jimmunol.194.supp.183.4.
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Abstract The loading of MHC-I molecules with peptides for cell surface display is a crucial step in self-tolerance and activation of CD8 T cells. We studied TAPBPR (TAP binding protein-related) protein, a tapasin homolog, which is widely expressed and IFN-γ inducible, but is not part of the classical MHC-I peptide-loading complex. We produced recombinant soluble TAPBPR and evaluated its interactions with several recombinant MHC-I molecules in vitro, by gel-shift, size exclusion chromatography, ultracentrifugation, and surface plasmon resonance. We show that TAPBPR binds MHC-I after photolysis of a bound peptide, and that the TAPBPR/MHC-I complex is dissociated by exposure to peptides that bind the MHC-I molecule, indicating a role of TAPBPR in stabilizing a peptide-receptive form of the MHC-I/β2m complex. Peptide-dependent release of MHC-I from TAPBPR is directly proportional to the peptide’s affinity for MHC-I. Peptide binding experiments indicate a role for TAPBPR in selection of high affinity peptides. Mutagenesis of TAPBPR and MHC-I confirm the importance of amino acid residues conserved with the putative tapasin/MHC-I binding site and reveal additional residues important for the TAPBPR/MHC-I interaction. Molecular docking simulations suggest a detailed mechanism for the interaction of TAPBPR with peptide free MHC-I. These studies are consistent with the view that TAPBPR functions as a chaperone that stabilizes peptide-free MHC-I to permit binding of high affinity peptides.
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Chatterjee, Sunanda, Rituparna Sinha Roy i P. Balaram. "Expanding the polypeptide backbone: hydrogen-bonded conformations in hybrid polypeptides containing the higher homologues of α-amino acids". Journal of The Royal Society Interface 4, nr 15 (23.01.2007): 587–606. http://dx.doi.org/10.1098/rsif.2006.0203.
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Half a century has passed since the hydrogen-bonded secondary structures of polypeptides and proteins were first recognized. An extraordinary wealth of conformational information is now available on peptides and proteins, which are formed of α-amino acid residues. More recently, the discovery of well-folded structures in oligopeptides containing β-amino acids has focused a great deal of current interest on the conformational properties of peptides constructed from higher homologues (ω) of α-amino acids. This review examines the nature of intramolecularly hydrogen-bonded conformations of hybrid peptides formed by amino acid residues, with a varying number of backbone atoms. The β-turn, a ubiquitous structural feature formed by two residue (αα) segments in proteins and peptides, is stabilized by a 10-atom (C 10 ) intramolecular 4→1 hydrogen bond. Hybrid turns may be classified by comparison with their αα counterparts. The available crystallographic information on hydrogen-bonded hybrid turns is surveyed in this review. Several recent examples demonstrate that individual ω-amino acid residues and hybrid dipeptide segments may be incorporated into the regular structures of α-peptides. Examples of both peptide helices and hairpins are presented. The present review explores the relationships between folded conformations in hybrid sequences and their counterparts in all α-residue sequences. The use of stereochemically constrained ω-residues promises to expand the range of peptide design strategies to include ω-amino acids. This approach is exemplified by well-folded structures like the C 12 (αγ) and C 14 (γγ) helices formed in short peptides containing multiply substituted γ-residues. The achiral γ-residue gabapentin is a readily accessible building block in the design of peptides containing γ-amino acids. The construction of globular polypeptide structures using diverse hybrid sequences appears to be a realistic possibility.
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Al-Attiyah, Raja, Fatema A. Shaban, Harald G. Wiker, Fredrik Oftung i Abu S. Mustafa. "Synthetic Peptides Identify Promiscuous Human Th1 Cell Epitopes of the Secreted Mycobacterial Antigen MPB70". Infection and Immunity 71, nr 4 (kwiecień 2003): 1953–60. http://dx.doi.org/10.1128/iai.71.4.1953-1960.2003.
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ABSTRACT MPB70 is a secreted protein of Mycobacterium bovis and Mycobacterium tuberculosis which stimulates both cellular and humoral immune responses during infection with bovine and human tubercle bacilli. In addition, vaccination with MPB70 has been shown to induce Th1 cell responses and protection in animal models of tuberculosis. The present study was carried out to map the dominant human Th1 cell epitopes of MPB70 in relation to major histocompatibility complex (MHC) class II restriction in healthy subjects showing strong T-cell responses to complex mycobacterial antigens. Peripheral blood mononuclear cells (PBMC) from HLA-DR-typed donors were tested with complex mycobacterial antigens (whole-cell M. tuberculosis and M. tuberculosis culture filtrates), with MPB70 purified from the culture filtrate of M. bovis BCG Tokyo, and with 13 synthetic peptides (25-mers overlapping by 10 residues) covering the sequence of MPB70. The donors that responded to the complex antigens and MPB70 also responded to the cocktail of synthetic MPB70 peptides. Testing of PBMC with individual peptides showed that peptides p5 (amino acids [aa] 61 to 85), p6 (aa 76 to 100), p8 (aa 106 to 130), p12 (aa 166 to 190), and p13 (aa 181 to 193) were most frequently recognized in proliferation and gamma interferon (IFN-γ) assays. Testing of antigen-specific CD4+ T-cell lines with the individual peptides of MPB70 confirmed that peptides p8, p12, and p13 contain immunodominant Th1 cell epitopes of MPB70. MHC restriction analysis with HLA-typed donors showed that MPB70 and its immunodominant peptides were presented to T cells promiscuously. The T-cell lines responding to MPB70 and peptides p8, p12, and p13 in IFN-γ assays mediated antigen-peptide-specific cytotoxic activity against monocytes/macrophages pulsed with the whole-protein antigen or the peptides. In conclusion, the promiscuous recognition of MPB70 and its immunodominant peptide defined epitopes (aa 106 to 130 and 166 to 193) by IFN-γ-producing Th1 cells supports possible application of this secreted antigen to subunit vaccine design.
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Provenzano, Maurizio, Simone Mocellin, Francesco M. Marincola i David F. Stroncek. "The Use of Algorithms with a Novel Score Standardization Method for the Selection of Candidate Immunogenic HLA-Specific Peptides Led to the Identification of New Immunogenic HLA-A*0201 Cytomegalovirus Epitopes." Blood 104, nr 11 (16.11.2004): 2862. http://dx.doi.org/10.1182/blood.v104.11.2862.2862.
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Abstract The identification of HLA class I restricted epitopes within immunogenic proteins that are capable of stimulating memory T lymphocytes is an important step for both clinical vaccine and adoptive immunotherapy. Despite the strong immunogenicity demonstrated by specific HLA restricted peptides, the peptide’s affinity to a specific HLA antigen may vary among individuals. Therefore, it is important to identify more than one immune determinant for each HLA antigen of interest. Two computer algorithms, one by Parker and another by Rammensee, are widely used in immunogenetic studies in order to predict which peptides bind best to specific HLA molecules. The use of these algorithms represents the first step in screening proteins. Parker’s algorithm ranks potential peptide according to the predictive half-time disassociation of peptide/MHC complexes. Rammensee’s algorithm ranks the peptides based on the presence of primary and secondary HLA-binding anchor residues. Starting with the sequence of Cytomegalovirus (CMV) phosphorylated matrix protein 65 (pp65; SwissProt ID: P06725), we derived from each algorithm a list of 250 nonamer (9-mer) peptides predicted to bind to the HLA-A*0201 allele. Standardizing the two groups of scores, corresponding to the endpoints of the stated interval, by the following formula: [(peptide score - mean of scores)/ standard deviation of scores], we obtained pure values that are independent of the unit of measurement, therefore homogeneous and thus comparable. This allowed us to link each peptide to a pair of values, one for each algorithm. The values derived from standardized Parker scores (X axis) were plotted against the values derived from standardized Rammensee scores (Y axis). We represented final results by a graph. All peptides having positive values with both algorithms and included in the first quadrant of the dot-scatter graph (double positive quadrant (+/+)) were likely to be highly immunogenic epitopes. Those peptides were included in a list of potential peptides to screen. In the presence of homoschedasticity, we selected only peptides showing mean values greater than 1 (among those having both the mean value greater than 0 and the standard deviation value greater than 1). Nine out of the 250 peptides were thus chosen within the CMV pp65 and their immunogenicity analyzed by ex vivo stimulation of PBMC and measured at the transcriptional level using the production of IFN-γ mRNA. Four out of nine peptides stimulated PBMCs from all HLA-A*0201 restricted CMV-seropositive subjects tested (p values: peptide #5, 0.011032; peptide #7, 0.015225; peptide #8, 0.025221; and peptide #9, 0.007302). The intracellular IFN-γ protein production by ex vivo peptide stimulation ranged from 0.14 to 0.62% compared to 0.03% for non stimulated cells. Moreover, each of the four selected peptide, either alone or in pool, was able to reactivate in vitro a strong immune T cell memory response, as measured by cytokine protein release and target cell lysis. The identification of multiple HLA class I restricted epitopes will allow the simultaneous administration of peptides with the ability to produce CMV-specific CTLs in patients bearing the same HLA types. This represents an extraordinary advantage for CMV adoptive immune therapy or vaccination.
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Lowry, Philip. "60 YEARS OF POMC: Purification and biological characterisation of melanotrophins and corticotrophins". Journal of Molecular Endocrinology 56, nr 4 (maj 2016): T1—T12. http://dx.doi.org/10.1530/jme-15-0260.
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The remarkable conservation of the primary structures and anatomical location of dogfish α-melanocyte-stimulating hormone (MSH), corticotrophin-like intermediate lobe peptide (CLIP) and adrenocorticotrophic hormone (ACTH) compared with mammals reinforced the tissue-specific processing hypothesis of ACTH peptides in the pituitary gland. The cloning of dogfish pro-opiomelanocortin (POMC) led to the identification of δ-MSH and simultaneously revealed the high conservation of the γ-MSH sequence during evolution. These studies have also shown that β-MSH is much less conserved during evolution and in some species is not even processed from β-LPH. Human pro-γ-MSH potentiates the corticosteroidogenic activity of ACTH and peptides generated from its N-terminal, in particular big-γ-MSH, appear to have adrenal mitogenic activity. Human big-γ-MSH (from the zona intermedia) may also cause the adrenache. The review finishes with a cautionary note with regard to the misdiagnosis of the ectopic ACTH syndrome in which partial processing of ACTH can result in large concentrations of α-MSH and CLIP, which can interfere in the performance of two-site immunoassays, and the problem of the correct disulphide bridge arrangement in synthetic N-POMC peptides is also discussed.
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Lebrun, Ivo, Olga B. Henriques, Fabiana L. A. S. Lebrun, Adriana K. Carmona, Luiz Juliano i Antonio C. M. Camargo. "Isolation and characterization of a new bradykinin potentiating octapeptide from γ-casein". Canadian Journal of Physiology and Pharmacology 73, nr 1 (1.01.1995): 85–91. http://dx.doi.org/10.1139/y95-012.
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Peptides that display bradykinin-potentiating activity have been obtained from a number of distinct sources, such as snake venoms, fibrinogen, and casein. This paper describes the isolation and sequencing of a novel bradykinin-potentiating peptide, generated by tryptic hydrolysis of the γ-casein chain. No homology was found to other known vasoactive or vasopotentiating peptides. The octapeptide Tyr-Pro-Val-Gln-Pro-Phe-Thr-Glu, corresponding to the γ-casein(114–121) sequence, was isolated from the tryptic hydrolysis of γ-casein and also synthesized by solid-phase peptide synthesis. Both natural and synthetic peptides had the same retention time in HPLC and displayed a selective potentiating activity on isolated guinea-pig ileum for bradykinin and Lys-bradykinin but were not able to potentiate the effects of Met-Lys-bradykinin, Ile-Ser-bradykinin, angiotensin II, acetylcholine, or histamine. Intravenous injections of bradykinin and of bradykinin-potentiating octapeptide produced a persistent hypotension in conscious rats, a pattern that was not obtained when the octapeptide was replaced by captopril. This bradykinin-potentiating octapeptide is a strong competitive inhibitor of endo-oligopeptidase A (EC 3.4.24.15, formerly EC 3.4.22.19), but it has low inhibitory potency towards angiotensin-converting enzyme (EC 3.4.15.1). Thus, our results suggest that other peptidases in addition to angiotensin-converting enzyme, such as endo-oligopeptidase A, may contribute to the reduction of the effective concentration of bradykinin in the circulation.Key words: bradykinin, potentiating peptides, casein, endo-oligopeptidase A, angiotensin-converting enzyme, smooth muscle, rat arterial blood pressure.
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Fuji, Shigeo, Julia Fischer, Markus Kapp, Thomas G. Bumm, Hermann Einsele, Stefan Stevanovic, Hans-Georg Rammensee, Thomas Hunig i Götz Ulrich Grigoleit. "Wilms Tumor Protein-1-Derived 9-Mer Peptide Induces CD4 T-Cell Responses in an HLA-DR Restricted Manner". Blood 120, nr 21 (16.11.2012): 4351. http://dx.doi.org/10.1182/blood.v120.21.4351.4351.
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Abstract Abstract 4351 Wilms‘ tumor protein-1 (WT1) is one of the most investigated tumor-associated antigens (TAA) in hematological malignancies. CD8 T-cell responses against several WT1-derived peptides have been characterized and are known to contribute to disease control after allogeneic hematopoietic stem cell transplantation (HSCT). Also the identification of human leukocyte antigen (HLA) class II-restricted CD4 T-cell epitopes from WT1 is a challenging task of T-cell-based cancer immunotherapy to improve the effectiveness of WT1 peptide vaccination. We found a highly immunogenic WT1 peptide composed of only 9 amino acids having the ability to induce IFN-γ secretion in CD4 T-cells in an HLA DR-restricted manner. This finding is of great interest as it was generally accepted that HLA class II binding peptides are composed of at least 12 amino acids being recognized by CD4 T-cells, whereas HLA class I binding peptides are composed of 8–11 amino acids being recognized by CD8 T-cells (Wang et al Mol. Immunol. 2002). However, both HLA class I and class II molecules bind to primary and secondary peptide anchor motifs covering the central 9–10 amino acids. Thus, considering this common structural basis for peptide binding there is a possibility that the WT1 9-mer peptide binds to HLA class II molecules, and induces CD4 T-cell responses. IFN-γ induction in response to several WT1 9-mer peptides was screened in 24 HLA-A*02:01 positive patients with acute myeloid leukemia or myelodysplastic syndrome after allogeneic HSCT. Responses to one WT1 9-mer peptide were exclusively detected in CD3+CD4+ T-cells of 2 patients after allogeneic HSCT, but not in CD3+CD4+ T-cells of their corresponding HSC donors. CD4+ T-cell responses to this WT1 9-mer peptide exhibited high levels of functional avidity, as IFN-γ induction was detected after stimulation with 100 ng peptide per mL. Peptide-induced IFN-γ production was confirmed with IFN-γ ELISPOT assays and the HLA restriction of the T-cell response was determined by HLA blocking antibodies. The reaction was significantly blocked by anti-pan HLA class II antibody (85 % reduction), but neither by pan-HLA class I nor by anti-HLA A2 antibody. To identify the subtype of HLA class II molecule, blocking assays with antibodies against HLA-DP, HLA-DR and HLA-DQ were performed. IFN-γ induction was completely abrogated by anti-HLA-DR antibody (99 % reduction) (fig 1, p value of unpaired student‘s t-test <0.0001 for the medium control vs anti-pan HLA class II antibody or anti-HLA-DR antibody, respectively). To test whether IFN-γ was exclusively induced in CD4 T cells, CD4 or CD8 T-cells were depleted from PBMC. Whereas CD8 T-cell depletion did not affect IFN-γ induction, CD4 T-cell depletion completely abrogated the WT1 9-mer peptide induced response (fig 2). CD4 T-cells responding to the WT1 9-mer peptide were indicated to be functional cytotoxic T-cells with an effector CD4 T-cell phenotype. Longitudinal analyses demonstrated the persistence and functionality of WT1 9-mer specific CD4 T-cells in PBMC of patients even at day 1368 after allogeneic HSCT. These data indicate for the first time that a TAA-derived 9-mer peptide can induce HLA class II-restricted CD4 T-cell responses. Vaccination with the characterized WT1 9-mer peptide can enhance the induction and maintenance of not only CD4 but also indirect CD8 T-cell responses. Considering that CD4 T-cells play an important role in tumor rejection, the possibility that other TAA-derived 9-mer peptides having the potential to induce CD4 T-cell responses should be explored in other settings of tumor immunology as well to improve vaccination strategies. Disclosures: No relevant conflicts of interest to declare.
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Carbone, David P., I. Frank Ciernik, Michael J. Kelley, M. Charles Smith, Sorena Nadaf, Denise Kavanaugh, V. Ellen Maher i in. "Immunization With Mutant p53- and K-ras–Derived Peptides in Cancer Patients: Immune Response and Clinical Outcome". Journal of Clinical Oncology 23, nr 22 (1.08.2005): 5099–107. http://dx.doi.org/10.1200/jco.2005.03.158.
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Purpose To determine the ability to induce tumor-specific immunity with individual mutant K-ras–or p53-derived peptides and to monitor clinical outcome. Patients and Methods Patients in varying stages of disease underwent genetic analysis for mutations in K-ras and p53. Thirty-nine patients were enrolled. Seventeen-mer peptides were custom synthesized to the corresponding mutation. Baseline immunity was assessed for cytotoxic T-lymphocyte (CTL) response and interferon gamma (IFN-γ) release from mutant peptide-primed lymphocytes. Patients' peripheral-blood mononuclear cells were pulsed with the corresponding peptide, irradiated, and applied intravenously. Patients were observed for CTL, IFN-γ, interleukin (IL) -2, IL-5, and granulocyte-macrophage colony-stimulating factor responses, for treatment-related toxicity, and for tumor response. Results No toxicity was observed. Ten (26%) of 38 patients had detectable CTL against mutant p53 or K-ras, and two patients were positive for CTL at baseline. Positive IFN-γ responses occurred in 16 patients (42%) after vaccination, whereas four patients had positive IFN-γ reaction before vaccination. Of 29 patients with evident disease, five experienced a period of stable disease. Favorable prognostic markers were detectable CTL activity and a positive IFN-γ reaction but not IL-5 release. Median survival times of 393 v 98 days for a positive versus negative CTL response (P = .04), respectively, and of 470 v 88 days for a positive versus negative IFN-γ response (P = .02), respectively, were detected. Conclusion Custom-made peptide vaccination is feasible without any toxicity. CTL and cytokine responses specific to a given mutation can be induced or enhanced with peptide vaccines. Cellular immunity to mutant p53 and K-ras oncopeptides is associated with longer survival.
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Al-Attiyah, R., i A. S. Mustafa. "Characterization of Human Cellular Immune Responses to Novel Mycobacterium tuberculosis Antigens Encoded by Genomic Regions Absent in Mycobacterium bovis BCG". Infection and Immunity 76, nr 9 (23.06.2008): 4190–98. http://dx.doi.org/10.1128/iai.00199-08.
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ABSTRACT Comparative genomics has identified several regions of differences (RDs) between the infectious Mycobacterium tuberculosis and the vaccine strains of Mycobacterium bovis BCG. We aimed to evaluate the cellular immune responses induced by antigens encoded by genes predicted in 11 RDs. Synthetic peptides covering the sequences of RD1, RD4 to RD7, RD9 to RD13, and RD15 were tested for antigen-induced proliferation and secretion of Th1 cytokine, gamma interferon (IFN-γ), by peripheral blood mononuclear cells (PBMC) obtained from culture-proven pulmonary tuberculosis (TB) patients and M. bovis BCG-vaccinated healthy subjects. Among the peptide pools, RD1 induced the best responses in both donor groups and in both assays. In addition, testing of TB patients' PBMC for secretion of proinflammatory cytokines (tumor necrosis factor alpha [TNF-α], interleukin 6 [IL-6], IL-8, and IL-1β), Th1 cytokines (IFN-γ, IL-2, and TNF-β), and Th2 cytokines (IL-4, IL-5, and IL-10) showed differential effects of RD peptides in the secretion of IFN-γ and IL-10, with high IFN-γ/IL-10 ratios (32 to 5.0) in response to RD1, RD5, RD7, RD9, and RD10 and low IFN-γ/IL-10 ratios (<1.0) in response to RD12, RD13, and RD15. Peptide-mixing experiments with PBMC from healthy subjects showed that secretion of large quantities of IL-10 in response to RD12 and RD13 correlated with inhibition of Th1 responses induced by RD1 peptides. In conclusion, our results suggest that M. tuberculosis RDs can be divided into two major groups—one group that activates PBMC to preferentially secrete IFN-γ and another group that activates preferential secretion of IL-10—and that these two groups of RDs may have roles in protection against and pathogenesis of TB, respectively.
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Yang, Juan, Weidong Bai, Xiaofang Zeng i Chun Cui. "γ-[Glu](n=1,2)-Phe/-Met/-Val stimulates gastrointestinal hormone (CCK and GLP-1) secretion by activating the calcium-sensing receptor". Food & Function 10, nr 7 (2019): 4071–80. http://dx.doi.org/10.1039/c9fo00313d.
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This study was conducted to discover the effectiveness of dietary peptides (γ-[Glu](n=1,2)-Phe/-Met/-Val) as stimulators of cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) secretion.
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Slezina, Marina P., Ekaterina A. Istomina, Tatyana V. Korostyleva i Tatyana I. Odintsova. "The γ-Core Motif Peptides of Plant AMPs as Novel Antimicrobials for Medicine and Agriculture". International Journal of Molecular Sciences 24, nr 1 (28.12.2022): 483. http://dx.doi.org/10.3390/ijms24010483.
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The γ-core motif is a structural element shared by most host antimicrobial peptides (AMPs), which is supposed to contribute to their antimicrobial properties. In this review, we summarized the available data on the γ-core peptides of plant AMPs. We describe γ-core peptides that have been shown to exhibit inhibitory activity against plant and human bacterial and fungal pathogens that make them attractive scaffolds for the development of novel anti-infective agents. Their advantages include origin from natural AMP sequences, broad-spectrum and potent inhibitory activity, and cost-effective production. In addition, some γ-core peptides combine antimicrobial and immunomodulatory functions, thus broadening the spectrum of practical applications. Some act synergistically with antimycotics and fungicides, so combinations of peptides with conventionally used antifungal agents can be suggested as an effective strategy to reduce the doses of potentially harmful chemicals. The presented information will pave the way for the design of novel antimicrobials on the basis of γ-core motif peptides, which can find application in medicine and the protection of crops from diseases.
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John, Chandy C., Ann M. Moormann, Peter O. Sumba, Ayub V. Ofulla, Daniel C. Pregibon i James W. Kazura. "Gamma Interferon Responses to Plasmodium falciparum Liver-Stage Antigen 1 and Thrombospondin-Related Adhesive Protein and Their Relationship to Age, Transmission Intensity, and Protection against Malaria". Infection and Immunity 72, nr 9 (wrzesień 2004): 5135–42. http://dx.doi.org/10.1128/iai.72.9.5135-5142.2004.
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ABSTRACT Gamma interferon (IFN-γ) responses to the Plasmodium falciparum antigens liver-stage antigen 1 (LSA-1) and thrombospondin-related adhesive protein (TRAP) are thought to be important in protection against malaria. Optimal methods of testing and the effects of age and transmission intensity on these responses are unknown. IFN-γ responses to LSA-1 and TRAP peptides were assessed by the enzyme-linked immunospot assay (ELISPOT) and enzyme-linked immunosorbent assay (ELISA) in children and adults from areas of stable and unstable malaria transmission in Kenya. Adults in the areas of stable and unstable transmission had similar frequencies and levels of IFN-γ responses to LSA-1 and TRAP as determined by ELISPOT and ELISA. In contrast, IFN-γ responses to the LSA-1 T3 peptide (assessed by ELISPOT) and to any LSA-1 peptide (assessed by ELISA) were less frequent in children in the area of unstable transmission than in children in the area of stable transmission. IFN-γ responses to LSA-1 were more frequently detected by ELISA than by ELISPOT in the stable-transmission area. IFN-γ responses detected by ELISA and ELISPOT did not correlate with each other. In children in the stable-transmission area, IFN-γ responses to LSA-1 peptides assessed by ELISA, but not by ELISPOT, were associated with protection against clinical malaria and anemia. IFN-γ responses to LSA-1 appear to require repeated P. falciparum exposure and/or increased age and, as measured by ELISA, are associated with protection against clinical malaria and anemia.
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DENEF, C., J. LU i E. SWINNEN. "γ-MSH Peptides in the Pituitary". Annals of the New York Academy of Sciences 994, nr 1 (czerwiec 2003): 123–32. http://dx.doi.org/10.1111/j.1749-6632.2003.tb03171.x.
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Jadhav, Sandip V., i Hosahudya N. Gopi. "Remarkable thermoresponsive nanofibers from γ-peptides". Chemical Communications 49, nr 80 (2013): 9179. http://dx.doi.org/10.1039/c3cc45383a.
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Sabatino, Denise E., Federico Mingozzi, Haifeng Chen, Peter Colosi, Hildegund C. J. Ertl i Katherine A. High. "Identification of the AAV2 Capsid CD8+ T Cell Epitope in C57BL/6 Mice." Blood 104, nr 11 (16.11.2004): 3188. http://dx.doi.org/10.1182/blood.v104.11.3188.3188.
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Abstract Recently, a clinical trial for adeno-associated virus serotype 2 (AAV2) mediated liver directed gene transfer of human Factor IX to subjects with severe hemophilia B revealed that two patients developed transient asymptomatic transaminitis following vector administration. Immunology studies in the second patient demonstrated a transient T cell response to AAV2 capsid peptides suggesting that the immune response to the AAV capsid may be related to the transient transaminitis. We hypothesized that the observations made in the human subjects were due to a CD8 T cell response to AAV2 capsid protein. Preclinical studies in mice and dogs, which are not naturally infected by wild type AAV2 viruses, did not predict these findings in the clinical study. Thus, we developed a mouse model in which we were able to mimic this phenomenon (Blood 102:493a). In an effort to further characterize the immune responses to AAV2 capsid proteins in this mouse model, we identified the T cell epitope in the AAV capsid protein recognized by murine C57Bl/6 CD8 T cells. A peptide library of AAV2 VP1 capsid peptides (n=145) that were synthesized as 15mers overlapping by 10 amino acids were divided into 6 pools each containing 24–25 peptides. C57Bl/6 mice were immunized intramuscularly with an adenovirus expressing AAV2 capsid protein. Nine days later the spleen was harvested and intracellular cytokine staining (ICS) was used to assess release of IFN-γ from CD8 T cells in response to 6 AAV2 capsid peptide pools. ICS demonstrated CD8 cells from mice immunized with Ad-AAV2 produced IFN-γ (3.5% of the CD8 cells) in response to Pool F (amino acid 119–145) while no IFN-γ release in CD8 cells was detected with Pool A to E (mean 0.28%±0.25%) compared to the media control (0.16%). This detection of IFN-γ release from CD8 T cells indicates a specific proliferation to a peptide(s) within this peptide pool (Pool F). A matrix approach was used to further define which peptide(s) contained the immunodominant epitope. Eleven small peptide pools of Pool F were created in which each peptide was represented in 2 pools. ICS of splenocytes from immunized (Ad-AAV2 capsid) C57Bl/6 mice demonstrated IFN-γ response from CD8 cells to 3 of the matrix pools corresponding to peptide 140 (PEIQYTSNYNKSVNV) and 141 (TSNYNKSVNVDFTVD) compared with media controls. To determine the exact peptide sequence that binds to the MHC Class I molecule, 9 amino acid peptides (n=7) were created that overlap peptide 140 and 141. Peptide SNYNKSVNV showed positive staining for both CD8 and IFN- γ(3.2%) compared with the six other peptides (0.14%±0.08%), media control (0.08%) and mice that were not immunized (0.11%). This epitope lies in the C terminus of the AAV2 VP1 capsid protein. Current studies using strains of mice with different MHC H2 haplotypes will allow us to determine which of the C57Bl/6 MHC alleles the epitope binds. These findings will provide us with a powerful tool for assessing immune responses to AAV capsid in the context of gene therapy. Specifically, they will allow us to determine how long immunologically detectable capsid sequences persist in an animal injected with AAV vectors. This in turn will provide a basis for a clinical study in which subjects are transiently immunosuppressed, from the time of vector injection until capsid epitopes are no longer detectable by the immune system.
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Hirao, Takashi, Masahide Sato, Akira Shirahata i Yoshiyuki Kamio. "Covalent Linkage of Polyamines to Peptidoglycan inAnaerovibrio lipolytica". Journal of Bacteriology 182, nr 4 (15.02.2000): 1154–57. http://dx.doi.org/10.1128/jb.182.4.1154-1157.2000.
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ABSTRACT Spermidine and cadaverine were found to be constituents of the cell wall peptidoglycan of Anaerovibrio lipolytica, a strictly anaerobic bacterium. The peptidoglycan was degraded with theN-acetylmuramyl-l-alanine amidase and endopeptidase into two peptide fragments, peptide I and peptide II, at a molar ratio of 4:1. Peptides I and II were identified asl-alanine–d-glutamic acid(αcadaverine)γ meso-diaminopimelic acid (DAP)–d-alanine andl-alanine–d-glutamic acid(αspermidine)γ meso-DAP–d-alanine, respectively. The N1-amino group of spermidine was linked to the α-carboxyl group of the d-glutamic acid residue of peptide II.
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Domitrovic, Tatiana, Tsutomu Matsui i John E. Johnson. "Dissecting Quasi-Equivalence in Nonenveloped Viruses: Membrane Disruption Is Promoted by Lytic Peptides Released from Subunit Pentamers, Not Hexamers". Journal of Virology 86, nr 18 (3.07.2012): 9976–82. http://dx.doi.org/10.1128/jvi.01089-12.
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Nonenveloped viruses often invade membranes by exposing hydrophobic or amphipathic peptides generated by a proteolytic maturation step that leaves a lytic peptide noncovalently associated with the viral capsid. Since multiple copies of the same protein form many nonenveloped virus capsids, it is unclear if lytic peptides derived from subunits occupying different positions in a quasi-equivalent icosahedral capsid play different roles in host infection. We addressed this question withNudaurelia capensis omega virus(NωV), an insect RNA virus with an icosahedral capsid formed by protein α, which undergoes autocleavage during maturation, producing the lytic γ peptide. NωV is a unique model because autocatalysis can be precisely initiatedin vitroand is sufficiently slow to correlate lytic activity with γ peptide production. Using liposome-based assays, we observed that autocatalysis is essential for the potent membrane disruption caused by NωV. We observed that lytic activity is acquired rapidly during the maturation program, reaching 100% activity with less than 50% of the subunits cleaved. Previous time-resolved structural studies of partially mature NωV particles showed that, during this time frame, γ peptides derived from the pentamer subunits are produced and are organized in a vertical helical bundle that is projected toward the particle surface, while identical polypeptides in quasi-equivalent subunits are produced later or are in positions inappropriate for release. Our functional data provide experimental support for the hypothesis that pentamers containing a central helical bundle, observed in different nonenveloped virus families, are a specialized lytic motif.
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Chan, Paul K. S., Shih-Jen Liu, T. H. Cheung, Winnie Yeo, S. M. Ngai, Jo L. K. Cheung, Pele Chong i Stephen Man. "T-Cell Response to Human Papillomavirus Type 58 L1, E6, and E7 Peptides in Women with Cleared Infection, Cervical Intraepithelial Neoplasia, or Invasive Cancer". Clinical and Vaccine Immunology 17, nr 9 (28.07.2010): 1315–21. http://dx.doi.org/10.1128/cvi.00105-10.
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ABSTRACT Human papillomavirus type 58 (HPV-58) exists in a relatively high prevalence in certain parts of the world, including East Asia. This study examined the T-cell response to HPV-58 L1, E6, and E7 peptides among women with cleared infection, cervical intraepithelial neoplasia grade 2 (CIN2) or CIN3, or invasive cervical cancer (ICC). Peptides found to be reactive in the in vitro peptide binding assay or mouse-stimulating study were tested with a gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay to detect peptide-specific responses from the peripheral blood mononuclear cells (PBMC) collected from 91 HPV-58-infected women (32 with cleared infection, 16 CIN2, 15 CIN3, and 28 ICC). Four HLA-A11-restricted HPV-58 L1 peptides, located at amino acid positions 296 to 304, 327 to 335, 101 to 109, and 469 to 477, showed positive IFN-γ ELISPOT results and were mainly from women with cleared infection. Two HLA-A11-restricted E6 peptides (amino acid positions 64 to 72 and 94 to 102) and three HLA-A11-restricted E7 peptides (amino acid positions 78 to 86, 74 to 82, and 88 to 96) showed a positive response. A response to E6 and E7 peptides was mainly observed from subjects with CIN2 or above. One HLA-A2-restricted E6 peptide, located at amino acid position 99 to 107, elicited a positive response in two CIN2 subjects. One HLA-A24-restricted L1 peptide, located at amino acid position 468 to 476, also elicited a positive response in two CIN2 subjects. In summary, this study has identified a few immunogenic epitopes for HPV-58 E6 and E7 proteins. It is worthwhile to further investigate whether responses to these epitopes have a role in clearing an established cervical lesion.
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Nlinwe, Omarine N., Ebenezer A. Ofori, Kwadwo Akyea-Mensah, Eric Kyei-Baafour, Harini Ganeshan, Maria Belmonte, Bjoern Peters, Eileen Villasante, Martha Sedegah i Kwadwo Asamoah Kusi. "Comparative analysis of the ex vivo IFN-gamma responses to CD8+ T cell epitopes within allelic forms of PfAMA1 in subjects with natural exposure to malaria". PLOS ONE 16, nr 9 (10.09.2021): e0257219. http://dx.doi.org/10.1371/journal.pone.0257219.
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Antigen polymorphisms in essential malarial antigens are a key challenge to the design and development of broadly effective malaria vaccines. The effect of polymorphisms on antibody responses is fairly well studied while much fewer studies have assessed this for T cell responses. This study investigated the effect of allelic polymorphisms in the malarial antigen apical membrane antigen 1 (AMA1) on ex vivo T cell-specific IFN-γ responses in subjects with lifelong exposure to malaria. Human leukocyte antigen (HLA) class I-restricted peptides from the 3D7 clone AMA1 were bioinformatically predicted and those with variant amino acid positions used to select corresponding allelic sequences from the 7G8, FVO, FC27 and tm284 parasite strains. A total of 91 AMA1 9-10mer peptides from the five parasite strains were identified, synthesized, grouped into 42 allele sets and used to stimulate PBMCs from seven HLA class 1-typed subjects in IFN-γ ELISpot assays. PBMCs from four of the seven subjects (57%) made positive responses to 18 peptides within 12 allele sets. Fifty percent of the 18 positive peptides were from the 3D7 parasite variant. Amino acid substitutions that were associated with IFN-γ response abrogation were more frequently found at positions 1 and 6 of the tested peptides, but substitutions did not show a clear pattern of association with response abrogation. Thus, while we show some evidence of polymorphisms affecting T cell response induction, other factors including TCR recognition of HLA-peptide complexes may also be at play.
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Aleanzi, Mabel, Ana María Demonte, Cecilia Esper, Silvia Garcilazo i Marta Waggener. "Celiac Disease". Clinical Chemistry 47, nr 11 (1.11.2001): 2023–28. http://dx.doi.org/10.1093/clinchem/47.11.2023.
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Abstract Background: Selective deamidation of glutamine residues by tissue transglutaminase (tTG) turns gliadin peptides into stronger activators of T cells from celiac disease (CD) patients. We examined the possibility that these modified peptides could be more specific epitopes for circulating antibodies than are native peptides. Methods: Two native synthetic peptides and their respective modified sequences were used as antigens for ELISA assays: peptide-1, with residues 56–75 of α-type gliadin; and peptide-2, with residues 134–153 of γ-type gliadin. We examined 40 CD patients [31 not being treated with a gluten-free diet (GFD) and 9 being treated with a GFD] and 30 non-CD patients. Results: An enhanced response against deamidated peptides was observed in 4 (IgA) and 22 (IgG) of 31 untreated CD patients for peptide-1 and in 25 (IgA) and 29 (IgG) patients for peptide-2. Higher anti-gliadin antibody and anti-tTG IgA concentrations correlated with increased IgA reactivity to modified peptides. Among the nine treated CD patients, eight also displayed an improved IgG signal for the deamidated sequence. Deamidation of peptides did not increase the reactivity of non-CD sera. Conclusions: Selective deamidation specifically increases circulating antibody recognition of gliadin peptides in CD patients. This suggests that deamidated gliadin peptides are more specific CD B-cell epitopes than native peptides; this finding may be relevant for designing improved diagnostic tests.
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Grison, Claude, Stéphane Genève, Stéphanie Claudel, Philippe Coutrot i Michel Marraud. "Catalytic hydrogenation of vinylogous peptides: a route towards γ-peptide foldamers". Tetrahedron Letters 44, nr 11 (marzec 2003): 2297–300. http://dx.doi.org/10.1016/s0040-4039(03)00272-7.
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Farrell, David H., Rehana S. Lovely i Lynn K. Boshkov. "Inhibition of Thrombin Cleavage of Factor VIII by Fibrinogen γ’ Chain Carboxyl Terminus." Blood 106, nr 11 (16.11.2005): 1957. http://dx.doi.org/10.1182/blood.v106.11.1957.1957.
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Fibrinogen can contain two types of γ chains, γA and γ’, that have identical sequences for the first 407 amino acids, but differ at their carboxyl termini. The γA chain contains four amino acids from γA 408–411, whereas the γ’ chain contains a different, highly anionic sequence of twenty amino acids from γ’ 408–427. This small change results in profound differences in the fibrinogen isoforms containing these distinct chains. The γ’ chain contains high affinity binding sites for zymogen factor XIII and for thrombin, and fibrinogen containing γ’ chains forms fibrin clots that are resistant to fibrinolysis. We have shown previously that the fibrinogen γ’ chain carboxyl terminus binds to thrombin exosite II, an anion-binding exosite known for its heparin binding activity. Recent reports show that the presence of the γ’ chain in fibrinogen reduces prothrombin activation in whole plasma assays. This inhibition may correspond to an activity originally described by Seegers in 1945 as “antithrombin I”, the adsorption of thrombin to fibrin. We have therefore investigated the enzymatic effects of γ’ peptide binding to thrombin in order to determine the role of the γ’ chain in the inhibition of prothrombin activation. In whole plasma, the γ’410–427 peptide prolonged the activated partial thromboplastin time (aPTT) in a dose-dependent manner, causing a delay in clotting from 29 seconds to 47 seconds at a concentration of 500 μM. A scrambled control peptide at the same concentration had little effect, increasing the clotting time to only 31.4 seconds. A series of γ’ deletion peptides were tested for their ability to prolong the aPTT. The inhibitory effect of the peptides corresponded in rank order to their thrombin binding affinity. In contrast to the aPTT, the prothrombin time increased only slightly from 11.7 seconds to 12.8 seconds (INR from 1.04 to 1.14) with the γ’410–427 peptide. This suggested that the γ’ peptide exerted its inhibitory effect on (a) component(s) of the intrinsic pathway, rather than the extrinsic pathway. We therefore investigated the effect of the γ’ peptide on thrombin activation of factor VIII, a thrombin substrate that, unlike factor V, is unique to the intrinsic pathway. Using purified factor VIII and thrombin in vitro, we showed that the γ’ peptide inhibited thrombin cleavage of factor VIII. However, this inhibitory effect was not due to direct inhibition of the thrombin active site, since the free γ’ peptide had little effect on thrombin cleavage of a small peptidyl substrate, tosyl-glycyl-prolyl-arginine-4-nitranilide acetate. These results suggest that factor VIII interactions with thrombin exosite II are essential for efficient cleavage of factor VIII, and support recent findings by others that interactions between thrombin exosite II and the A2 domain of factor VIII facilitate thrombin-catalyzed cleavage. These findings may explain, at least in part, the inhibitory effect of the γ’ chain on prothrombin activation in plasma.
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Barre, Annick, Hervé Benoist i Pierre Rougé. "Impacts of Sourdough Technology on the Availability of Celiac Peptides from Wheat α- and γ-Gliadins: In Silico Approach". Allergies 3, nr 1 (3.02.2023): 39–57. http://dx.doi.org/10.3390/allergies3010004.
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Celiac peptide-generating α- and γ-gliadins consist of a disordered N-terminal domain extended by an α-helical-folded C-terminal domain. Celiac peptides, primarily located along the disordered part of α- and γ-gliadin molecules, are nicely exposed and directly accessible to proteolytic enzymes occurring in the gastric (pepsin) and intestinal (trypsin, chymotrypsin) fluids. More than half of the potential celiac peptides identified so far in gliadins exhibit cleavage sites for pepsin. However, celiac peptides proteolytically truncated by one or two amino acid residues could apparently retain some activity toward HLA-DQ2 and HLA-DQ8 receptors in docking experiments. Together with the uncleaved peptides, these still active partially degraded CD peptides account for the incapacity of the digestion process to inactivate CD peptides from gluten proteins. In contrast, sourdough fermentation processes involve other proteolytic enzymes susceptible to the deep degradation of celiac peptides. In particular, sourdough supplemented by fungal prolyl endoproteases enhances the degrading capacities of the sourdough fermentation process toward celiac peptides. Nevertheless, since tiny amounts of celiac peptides sufficient to trigger deleterious effects on CD people can persist in sourdough-treated bread and food products, it is advisable to avoid consumption of sourdough-treated food products for people suffering from celiac disease. As an alternative, applying the supplemented sourdough process to genetically modified low gluten or celiac-safe wheat lines should result in food products that are safer for susceptible and CD people.
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Asledottir, Tora, Rashida Rehman, Gianfranco Mamone, Gianluca Picariello, Tove Gulbrandsen Devold, Gerd Elisabeth Vegarud, Arne Røseth i in. "Ancestral Wheat Types Release Fewer Celiac Disease Related T Cell Epitopes than Common Wheat upon Ex Vivo Human Gastrointestinal Digestion". Foods 9, nr 9 (25.08.2020): 1173. http://dx.doi.org/10.3390/foods9091173.
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Celiac disease (CeD) is an autoimmune enteropathy triggered by immunogenic gluten peptides released during the gastrointestinal digestion of wheat. Our aim was to identify T cell epitope-containing peptides after ex vivo digestion of ancestral (einkorn, spelt and emmer) and common (hexaploid) wheat (Fram, Bastian, Børsum and Mirakel) using human gastrointestinal juices. Wheat porridge was digested using a static ex vivo model. Peptides released after 240 min of digestion were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ESI MS/MS). Ex vivo digestion released fewer T cell epitope-containing peptides from the ancestral wheat varieties (einkorn (n = 38), spelt (n = 45) and emmer (n = 68)) compared to the common wheat varieties (Fram (n = 72), Børsum (n = 99), Bastian (n = 155) and Mirakel (n = 144)). Neither the immunodominant 33mer and 25mer α-gliadin peptides, nor the 26mer γ-gliadin peptide, were found in any of the digested wheat types. In conclusion, human digestive juice was able to digest the 33mer and 25mer α-gliadin, and the 26mer γ-gliadin derived peptides, while their fragments still contained naive T cell reactive epitopes. Although ancestral wheat released fewer immunogenic peptides after human digestion ex vivo, they are still highly toxic to celiac patients. More general use of these ancient wheat variants may, nevertheless, reduce CeD incidence.