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Hung SC, Hou T, Jiang W, Wang N, Qiao SW, Chow IT, Liu X, van der Burg SH, Koelle DM, Kwok WW, Sollid LM, Mellins ED. Epitope Selection for HLA-DQ2 Presentation: Implications for Celiac Disease and Viral Defense. THE JOURNAL OF IMMUNOLOGY 2019; 202:2558-2569. [PMID: 30926644 DOI: 10.4049/jimmunol.1801454] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 03/01/2019] [Indexed: 01/28/2023]
Abstract
We have reported that the major histocompatibility molecule HLA-DQ2 (DQA1*05:01/DQB1*02:01) (DQ2) is relatively resistant to HLA-DM (DM), a peptide exchange catalyst for MHC class II. In this study, we analyzed the role of DQ2/DM interaction in the generation of DQ2-restricted gliadin epitopes, relevant to celiac disease, or DQ2-restricted viral epitopes, relevant to host defense. We used paired human APC, differing in DM expression (DMnull versus DMhigh) or differing by expression of wild-type DQ2, versus a DM-susceptible, DQ2 point mutant DQ2α+53G. The APC pairs were compared for their ability to stimulate human CD4+ T cell clones. Despite higher DQ2 levels, DMhigh APC attenuated T cell responses compared with DMnull APC after intracellular generation of four tested gliadin epitopes. DMhigh APC expressing the DQ2α+53G mutant further suppressed these gliadin-mediated responses. The gliadin epitopes were found to have moderate affinity for DQ2, and even lower affinity for the DQ2 mutant, consistent with DM suppression of their presentation. In contrast, DMhigh APC significantly promoted the presentation of DQ2-restricted epitopes derived intracellularly from inactivated HSV type 2, influenza hemagglutinin, and human papillomavirus E7 protein. When extracellular peptide epitopes were used as Ag, the DQ2 surface levels and peptide affinity were the major regulators of T cell responses. The differential effect of DM on stimulation of the two groups of T cell clones implies differences in DQ2 presentation pathways associated with nonpathogen- and pathogen-derived Ags in vivo.
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Affiliation(s)
- Shu-Chen Hung
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305.,Program in Immunology, Stanford University, Stanford, CA 94305
| | - Tieying Hou
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305.,Program in Immunology, Stanford University, Stanford, CA 94305
| | - Wei Jiang
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305.,Program in Immunology, Stanford University, Stanford, CA 94305
| | - Nan Wang
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305.,Program in Immunology, Stanford University, Stanford, CA 94305
| | - Shuo-Wang Qiao
- Centre for Immune Regulation, Department of Immunology, University of Oslo and Oslo University Hospital, Rikshospitalet, 0372 Oslo, Norway.,K.G. Jebsen Coeliac Disease Research Centre, University of Oslo, 0424 Oslo, Norway
| | - I-Ting Chow
- Benaroya Research Institute at Virginia Mason, Seattle, WA 98101
| | - Xiaodan Liu
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305.,Program in Immunology, Stanford University, Stanford, CA 94305
| | - Sjoerd H van der Burg
- Department of Medical Oncology, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - David M Koelle
- Department of Medicine, University of Washington, Seattle, WA 98195.,Department of Laboratory Medicine, University of Washington, Seattle, WA 98195; and.,Department of Global Health, University of Washington, Seattle, WA 98195
| | - William W Kwok
- Benaroya Research Institute at Virginia Mason, Seattle, WA 98101
| | - Ludvig M Sollid
- Centre for Immune Regulation, Department of Immunology, University of Oslo and Oslo University Hospital, Rikshospitalet, 0372 Oslo, Norway.,K.G. Jebsen Coeliac Disease Research Centre, University of Oslo, 0424 Oslo, Norway
| | - Elizabeth D Mellins
- Division of Human Gene Therapy, Department of Pediatrics, Stanford University, Stanford, CA 94305; .,Program in Immunology, Stanford University, Stanford, CA 94305
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Wang N, Rajasekaran N, Hou T, Macaubas C, Mellins ED. Immunological Basis for Rapid Progression of Diabetes in Older NOD Mouse Recipients Post BM-HSC Transplantation. PLoS One 2015; 10:e0128494. [PMID: 26020954 PMCID: PMC4447290 DOI: 10.1371/journal.pone.0128494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 04/27/2015] [Indexed: 01/07/2023] Open
Abstract
Type I diabetes (T1D), mediated by autoreactive T cell destruction of insulin-producing islet beta cells, has been treated with bone marrow-derived hematopoietic stem cell (BM-HSC) transplantation. Older non-obese diabetic (NOD) mice recipients (3m, at disease-onset stage) receiving syngeneic BM-HSC progressed more rapidly to end-stage diabetes post-transplantation than younger recipients (4-6w, at disease-initiation stage). FACS analyses showed a higher percentage and absolute number of regulatory T cells (Treg) and lower proportion of proliferating T conventional cells (Tcon) in pancreatic lymph nodes from the resistant mice among the younger recipients compared to the rapid progressors among the older recipients. Treg distribution in spleen, mesenteric lymph nodes (MLN), blood and thymus between the two groups was similar. However, the percentage of thymic Tcon and the proliferation of Tcon in MLN and blood were lower in the young resistants. These results suggest recipient age and associated disease stage as a variable to consider in BM-HSC transplantation for treating T1D.
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MESH Headings
- Aging/immunology
- Aging/pathology
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Biomarkers/metabolism
- Blood Glucose/immunology
- Blood Glucose/metabolism
- Diabetes Mellitus, Type 1/immunology
- Diabetes Mellitus, Type 1/mortality
- Diabetes Mellitus, Type 1/pathology
- Diabetes Mellitus, Type 1/therapy
- Disease Models, Animal
- Female
- Forkhead Transcription Factors/genetics
- Forkhead Transcription Factors/immunology
- Gene Expression
- Hematopoietic Stem Cell Transplantation
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/immunology
- Immunophenotyping
- Lymphocyte Count
- Mice
- Mice, Inbred NOD
- Survival Analysis
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/pathology
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/pathology
- Whole-Body Irradiation
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Affiliation(s)
- Nan Wang
- Program in Immunology, Division of Human Gene Therapy, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Narendiran Rajasekaran
- Program in Immunology, Division of Human Gene Therapy, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Tieying Hou
- Program in Immunology, Division of Human Gene Therapy, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Claudia Macaubas
- Program in Immunology, Division of Human Gene Therapy, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Elizabeth D. Mellins
- Program in Immunology, Division of Human Gene Therapy, Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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Aydintug MK, Zhang L, Wang C, Liang D, Wands JM, Michels AW, Hirsch B, Day BJ, Zhang G, Sun D, Eisenbarth GS, O'Brien RL, Born WK. γδ T cells recognize the insulin B:9-23 peptide antigen when it is dimerized through thiol oxidation. Mol Immunol 2014; 60:116-28. [PMID: 24853397 PMCID: PMC4091716 DOI: 10.1016/j.molimm.2014.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 04/14/2014] [Accepted: 04/20/2014] [Indexed: 01/08/2023]
Abstract
The insulin peptide B:9-23 is a natural antigen in the non-obese diabetic (NOD) mouse model of type 1 diabetes (T1D). In addition to αβ T cells and B cells, γδ T cells recognize the peptide and infiltrate the pancreatic islets where the peptide is produced within β cells. The peptide contains a cysteine in position 19 (Cys19), which is required for the γδ but not the αβ T cell response, and a tyrosine in position 16 (Tyr16), which is required for both. A peptide-specific mAb, tested along with the T cells, required neither of the two amino acids to bind the B:9-23 peptide. We found that γδ T cells require Cys19 because they recognize the peptide antigen in an oxidized state, in which the Cys19 thiols of two peptide molecules form a disulfide bond, creating a soluble homo-dimer. In contrast, αβ T cells recognize the peptide antigen as a reduced monomer, in complex with the MHCII molecule I-A(g7). Unlike the unstructured monomeric B:9-23 peptide, the γδ-stimulatory homo-dimer adopts a distinct secondary structure in solution, which differs from the secondary structure of the corresponding portion of the native insulin molecule. Tyr16 is required for this adopted structure of the dimerized insulin peptide as well as for the γδ response to it. This observation is consistent with the notion that γδ T cell recognition depends on the secondary structure of the dimerized insulin B:9-23 antigen.
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Affiliation(s)
- M Kemal Aydintug
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA
| | - Li Zhang
- Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, Aurora, CO 80045, USA
| | - Chao Wang
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA
| | - Dongchun Liang
- Department of Ophthalmology, Doheny Eye Institute, University of Southern California, Los Angeles, CA 90033, USA
| | - J M Wands
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA
| | - Aaron W Michels
- Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, Aurora, CO 80045, USA
| | - Brooke Hirsch
- Department of Biomolecular Structure, University of Colorado Denver, Anschutz Medical Campus, Aurora CO 80045, USA
| | - Brian J Day
- Department of Medicine, National Jewish Health, 1400 Jackson Street, CO 80206, USA
| | - Gongyi Zhang
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA
| | - Deming Sun
- Department of Ophthalmology, Doheny Eye Institute, University of Southern California, Los Angeles, CA 90033, USA
| | - George S Eisenbarth
- Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, Aurora, CO 80045, USA
| | - Rebecca L O'Brien
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA
| | - Willi K Born
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, 1400 Jackson Street, Denver, CO 80206, USA.
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De Riva A, Busch R. MHC Class II Protein Turnover In vivo and Its Relevance for Autoimmunity in Non-Obese Diabetic Mice. Front Immunol 2013; 4:399. [PMID: 24324466 PMCID: PMC3839011 DOI: 10.3389/fimmu.2013.00399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/08/2013] [Indexed: 11/19/2022] Open
Abstract
Major histocompatibility complex class II (MHCII) proteins are loaded with endosomal peptides and reside at the surface of antigen-presenting cells (APCs) for a time before being degraded. In vitro, MHCII protein levels and turnover are affected by peptide loading and by rates of ubiquitin-dependent internalization from the cell surface, which is in turn affected by APC type and activation state. Prior work suggested that fast turnover of disease-associated MHCII alleles may contribute to autoimmunity. We recently developed novel stable isotope tracer techniques to test this hypothesis in vivo. In non-obese diabetic (NOD) mice, a model of type 1 diabetes (T1D), MHCII turnover was affected by APC type, but unaffected by disease-associated structural polymorphism. Differences in MHCII turnover were observed between NOD colonies with high and low T1D incidence, but fast turnover was dispensable for autoimmunity. Moreover, NOD mice with gene knockouts of peptide loading cofactors do not develop T1D. Thus, fast turnover does not appear pathogenic, and conventional antigen presentation is critical for autoimmunity in NOD mice. However, shared environmental factors may underpin colony differences in MHCII protein turnover, immune regulation, and pathogenesis.
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Affiliation(s)
| | - Robert Busch
- Department of Medicine, University of Cambridge, Cambridge, UK
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Wang N, Rajasekaran N, Hou T, Mellins ED. Transgene expression in various organs post BM-HSC transplantation. Stem Cell Res 2013; 12:209-21. [PMID: 24270160 DOI: 10.1016/j.scr.2013.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 10/17/2013] [Accepted: 10/26/2013] [Indexed: 11/29/2022] Open
Abstract
Gene therapy mediated by bone marrow-derived hematopoietic stem cells (BM-HSC) has been widely used in treating genetic deficiencies in both pre-clinical and clinical settings. Using mitotically inactive cell-targeting lentivirus with separate promoters for our gene of interest (the murine MHC class II (MHCII) chaperone, invariant chain (Ii)) and a GFP reporter, we monitored the expression and function of introduced Ii in various types of professional antigen presenting cells (B cells, macrophages and DC) from different organs (spleen, pancreatic lymph nodes (PLN), BM and blood). Ii and GFP were detected. Ii levels correlated with GFP levels only in macrophages and monocytes from spleen, monocytes from PLN and macrophage precursors from blood. By cell type, Ii levels in PLN cells were more similar to those in spleen cells than to those in blood or BM cells. Functionally, Ii expressed in PLN or spleen had more effect on MHCII abundance than Ii expressed in BM or blood. The results have implications for analysis of the outcomes of gene therapy when both therapeutic and reporter genes are introduced. The findings also have implications for understanding the development of immune molecule function.
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Affiliation(s)
- Nan Wang
- Department of Pediatrics, Program in Immunology, Program in Human Gene Therapy, Stanford University School of Medicine, Stanford, CA, USA.
| | - Narendiran Rajasekaran
- Department of Pediatrics, Program in Immunology, Program in Human Gene Therapy, Stanford University School of Medicine, Stanford, CA, USA.
| | - Tieying Hou
- Department of Pediatrics, Program in Immunology, Program in Human Gene Therapy, Stanford University School of Medicine, Stanford, CA, USA.
| | - Elizabeth D Mellins
- Department of Pediatrics, Program in Immunology, Program in Human Gene Therapy, Stanford University School of Medicine, Stanford, CA, USA.
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Wang N, Rajasekaran N, Hou T, Lisowski L, Mellins ED. Comparison of transduction efficiency among various lentiviruses containing GFP reporter in bone marrow hematopoietic stem cell transplantation. Exp Hematol 2013; 41:934-43. [PMID: 23954710 PMCID: PMC3833897 DOI: 10.1016/j.exphem.2013.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/05/2013] [Accepted: 07/25/2013] [Indexed: 10/26/2022]
Abstract
HIV-derived lentiviral vectors have been used widely to transduce non-dividing cells, such as hematopoietic stem cells (HSCs), in the setting of gene therapy. In this study, we screened lentiviral vectors for their ability to drive expression of the murine MHC class II chaperone, invariant chain (Ii) and a GFP reporter. The vectors included T2A vector with T2A-separated Ii and GFP under the same MSCV promoter, dual-promoter vectors with separate promoters for Ii and GFP (called MSCV or EF1a according to the promoter driving Ii expression), and a vector with EF1a driving a fusion of Ii/GFP (called Fusion vector). T2A and MSCV induced the highest levels of Ii and GFP expression, respectively, after direct transfection of 293T cells. All vectors except the Fusion vector drove expression of functional Ii, based on the enhancement of MHC class II level, which is a known consequence of Ii expression. Comparing the vectors after they were packaged into lentiviruses and used to transduce 293T, we found that MSCV and EF1a vectors mediated higher Ii and GFP expression. In ckit(+) bone marrow (BM) cells, MSCV still induced the highest Ii and GFP expression, whereas EF1a induced only robust Ii expression. Regardless of the vector, both Ii and GFP levels were significantly reduced in BM cells compared to 293T cells. When in vivo expression was assessed in cells derived from MSCV-transduced BM-HSCs, up to 80% of myeloid cells were GFP(+), but no Ii expression was observed. In contrast, transplantation of EF1a-transduced BM-HSCs led to much higher in vivo Ii expression. Thus, among those compared, dual-promoter vector-based lentivirus with the EF1a promoter driving the gene of interest is optimal for murine BM-HSC transduction.
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Affiliation(s)
| | | | | | - Leszek Lisowski
- Departments of Pediatrics and Genetics, Program in Human Gene Therapy, Stanford University School of Medicine, Stanford, CA
| | - Elizabeth D. Mellins
- Corresponding author at: Prof. Elizabeth D. Mellins, M.D., CCSR 2105c, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5164, USA, Tel: 650-498-7350, Fax: 650-498-6540,
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7
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De Riva A, Varley MC, Bluck LJ, Cooke A, Deery MJ, Busch R. Accelerated turnover of MHC class II molecules in nonobese diabetic mice is developmentally and environmentally regulated in vivo and dispensable for autoimmunity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 190:5961-71. [PMID: 23677470 PMCID: PMC3785126 DOI: 10.4049/jimmunol.1300551] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The H2-A(g7) (A(g7)) MHC class II (MHCII) allele is required for type 1 diabetes (T1D) in NOD mice. A(g7) not only has a unique peptide-binding profile, it was reported to exhibit biochemical defects, including accelerated protein turnover. Such defects were proposed to impair Ag presentation and, thus, self-tolerance. Here, we report measurements of MHCII protein synthesis and turnover in vivo. NOD mice and BALB/c controls were labeled continuously with heavy water, and splenic B cells and dendritic cells were isolated. MHCII molecules were immunoprecipitated and digested with trypsin. Digests were analyzed by liquid chromatography/mass spectrometry to quantify the fraction of newly synthesized MHCII molecules and, thus, turnover. MHCII turnover was faster in dendritic cells than in B cells, varying slightly between mouse strains. Some A(g7) molecules exhibited accelerated turnover in B cells from young, but not older, prediabetic female NOD mice. This acceleration was not detected in a second NOD colony with a high incidence of T1D. Turnover rates of A(g7) and H2-A(d) were indistinguishable in (NOD × BALB/c) F1 mice. In conclusion, accelerated MHCII turnover may occur in NOD mice, but it reflects environmental and developmental regulation, rather than a structural deficit of the A(g7) allele. Moreover, this phenotype wanes before the onset of overt T1D and is dispensable for the development of autoimmune diabetes. Our observations highlight the importance of in vivo studies in understanding the role of protein turnover in genotype/phenotype relationships and offer a novel approach for addressing this fundamental research challenge.
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Affiliation(s)
| | - Mark C. Varley
- Department of Medicine, University of Cambridge, Cambridge, UK
- Department of Engineering, University of Cambridge, Cambridge, UK
| | - Leslie J. Bluck
- Elsie Widdowson Laboratories, Medical Research Council Human Nutrition Research, Fulbourn, Cambridge, UK
| | - Anne Cooke
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Michael J. Deery
- Cambridge Centre for Proteomics, University of Cambridge, Cambridge, UK
| | - Robert Busch
- Department of Medicine, University of Cambridge, Cambridge, UK
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On the perils of poor editing: regulation of peptide loading by HLA-DQ and H2-A molecules associated with celiac disease and type 1 diabetes. Expert Rev Mol Med 2012; 14:e15. [PMID: 22805744 DOI: 10.1017/erm.2012.9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This review discusses mechanisms that link allelic variants of major histocompatibility complex (MHC) class II molecules (MHCII) to immune pathology. We focus on HLA (human leukocyte antigen)-DQ (DQ) alleles associated with celiac disease (CD) and type 1 diabetes (T1D) and the role of the murine DQ-like allele, H2-Ag7 (I-Ag7 or Ag7), in murine T1D. MHCII molecules bind peptides, and alleles vary in their peptide-binding specificity. Disease-associated alleles permit binding of disease-inducing peptides, such as gluten-derived, Glu-/Pro-rich gliadin peptides in CD and peptides from islet autoantigens, including insulin, in T1D. In addition, the CD-associated DQ2.5 and DQ8 alleles are unusual in their interactions with factors that regulate their peptide loading, invariant chain (Ii) and HLA-DM (DM). The same alleles, as well as other T1D DQ risk alleles (and Ag7), share nonpolar residues in place of Asp at β57 and prefer peptides that place acidic side chains in a pocket in the MHCII groove (P9). Antigen-presenting cells from T1D-susceptible mice and humans retain CLIP because of poor DM editing, although underlying mechanisms differ between species. We propose that these effects on peptide presentation make key contributions to CD and T1D pathogenesis.
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Hou T, Macmillan H, Chen Z, Keech CL, Jin X, Sidney J, Strohman M, Yoon T, Mellins ED. An insertion mutant in DQA1*0501 restores susceptibility to HLA-DM: implications for disease associations. THE JOURNAL OF IMMUNOLOGY 2011; 187:2442-52. [PMID: 21775680 DOI: 10.4049/jimmunol.1100255] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
HLA-DM (DM) catalyzes CLIP release, stabilizes MHC class II molecules, and edits the peptide repertoire presented by class II. Impaired DM function may have profound effects on Ag presentation events in the thymus and periphery that are critical for maintenance of self-tolerance. The associations of the HLA-DQ2 (DQ2) allele with celiac disease and type 1 diabetes mellitus have been appreciated for a long time. The explanation for these associations, however, remains unknown. We previously found that DQ2 is a poor substrate for DM. In this study, to further characterize DQ2-DM interaction, we introduced point mutations into DQ2 on the proposed DQ2-DM interface to restore the sensitivity of DQ2 to DM. The effects of mutations were investigated by measuring the peptide dissociation and exchange rate in vitro, CLIP and DQ2 expression on the cell surface, and the presentation of α-II-gliadin epitope (residues 62-70) to murine, DQ2-restricted T cell hybridomas. We found that the three α-chain mutations (α+53G, α+53R, or αY22F) decreased the intrinsic stability of peptide-class II complex. More interestingly, the α+53G mutant restored DQ2 sensitivity to DM, likely due to improved interaction with DM. Our data also suggest that α-II-gliadin 62-70 is a DM-suppressed epitope. The DQ2 resistance to DM changes the fate of this peptide from a cryptic to an immunodominant epitope. Our findings elucidate the structural basis for reduced DQ2-DM interaction and have implications for mechanisms underlying disease associations of DQ2.
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Affiliation(s)
- Tieying Hou
- Department of Pediatrics, Program in Immunology, Stanford University, Stanford, CA 94305, USA
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