The molecular basis underlying T cell specificity towards citrullinated epitopes presented by HLA-DR4.

CD4+ T cells recognising citrullinated self-epitopes presented by HLA-DRB1 bearing the shared susceptibility epitope (SE) are implicated in rheumatoid arthritis (RA). However, the underlying T cell receptor (TCR) determinants of epitope specificity towards distinct citrullinated peptide antigens, including vimentin-64cit59-71 and α-enolase-15cit10-22 remain unclear. Using HLA-DR4-tetramers, we examine the T cell repertoire in HLA-DR4 transgenic mice and observe biased TRAV6 TCR gene usage across these two citrullinated epitopes which matches with TCR bias previously observed towards the fibrinogen ß-74cit69-81 epitope. Moreover, shared TRAV26-1 gene usage is evident in four α-enolase-15cit10-22 reactive T cells in three human samples. Crystal structures of mouse TRAV6+ and human TRAV26-1+ TCR-HLA-DR4 complexes presenting vimentin-64cit59-71 and α-enolase-15cit10-22, respectively, show three-way interactions between the TCR, SE, citrulline, and the basis for the biased selection of TRAV genes. Position 2 of the citrullinated epitope is a key determinant underpinning TCR specificity. Accordingly, we provide a molecular basis of TCR specificity towards citrullinated epitopes.

Oral Insulin Delay of Stage 3 Type 1 Diabetes Revisited in HLA DR4-DQ8 Participants in the TrialNet Oral Insulin Prevention Trial (TN07).

OBJECTIVE: To explore if oral insulin could delay onset of stage 3 type 1 diabetes (T1D) among patients with stage 1/2 who carry HLA DR4-DQ8 and/or have elevated levels of IA-2 autoantibodies (IA-2As). RESEARCH AND METHODS: Next-generation targeted sequencing technology was used to genotype eight HLA class II genes (DQA1, DQB1, DRB1, DRB3, DRB4, DRB5, DPA1, and DPB1) in 546 participants in the TrialNet oral insulin preventative trial (TN07). Baseline levels of autoantibodies against insulin (IAA), GAD65 (GADA), and IA-2A were determined prior to treatment assignment. Available clinical and demographic covariables from TN07 were used in this post hoc analysis with the Cox regression model to quantify the preventive efficacy of oral insulin. RESULTS: Oral insulin reduced the frequency of T1D onset among participants with elevated IA-2A levels (HR 0.62; P = 0.012) but had no preventive effect among those with low IA-2A levels (HR 1.03; P = 0.91). High IA-2A levels were positively associated with the HLA DR4-DQ8 haplotype (OR 1.63; P = 6.37 × 10-6) and negatively associated with the HLA DR7-containing DRB1*07:01-DRB4*01:01-DQA1*02:01-DQB1*02:02 extended haplotype (OR 0.49; P = 0.037). Among DR4-DQ8 carriers, oral insulin delayed the progression toward stage 3 T1D onset (HR 0.59; P = 0.027), especially if participants also had high IA-2A level (HR 0.50; P = 0.028). CONCLUSIONS: These results suggest the presence of a T1D endotype characterized by HLA DR4-DQ8 and/or elevated IA-2A levels; for those patients with stage 1/2 disease with such an endotype, oral insulin delays the clinical T1D onset.

Gut microbiota as a sensor of autoimmune response and treatment for rheumatoid arthritis.

Rheumatoid arthritis (RA) is considered a multifactorial condition where interaction between the genetic and environmental factors lead to immune dysregulation causing autoreactivity. While among the various genetic factors, HLA-DR4 and DQ8, have been reported to be the strongest risk factors, the role of various environmental factors has been unclear. Though events initiating autoreactivity remain unknown, a mucosal origin of RA has gained attention based on the recent observations with the gut dysbiosis in patients. However, causality of gut dysbiosis has been difficult to prove in humans. Mouse models, especially mice expressing RA-susceptible and -resistant HLA class II genes have helped unravel the complex interactions between genetic factors and gut microbiome. This review describes the interactions between HLA genes and gut dysbiosis in sex-biased preclinical autoreactivity and discusses the potential use of endogenous commensals as indicators of treatment efficacy as well as therapeutic tool to suppress pro-inflammatory response in rheumatoid arthritis.

Analysis of HLA Profiles in 390 Uveitis Cases: Insights into Clinical Presentations.

Objective: This study aimed to explain the associations between different types of uveitis and human leukocyte antigen (HLA)-B27, HLA-DR4, and HLA-DRw53. Methods: A retrospective analysis of 390 uveitis cases was conducted among inpatients and outpatients diagnosed at Weifang Eye Hospital from 2013 to 2016. All 390 patients underwent HLA-B27 examination, and an additional 40 patients underwent examination for HLA-DR4 and HLA-DRw53. Gender, age, corrected visual acuity (CVA), and recurrence frequency were statistically analyzed based on the onset site and etiology classification. Results: Among the 390 enrolled patients, 206 were male, and 183 were female, with ages ranging from 6 to 87 years (mean: 44.2). The disease onset was classified into anterior uveitis (AU), panuveitis (panU), posterior uveitis (PU), and intermediate uveitis in 180, 112, 88, and 10 cases, respectively. HLA-B27 was positive in 94 cases (53 males and 41 females), yielding a positive rate of 24.1%. In AU patients, 80 (44.4%) tested positive for HLA-B27, while 8 (7.1%) panU patients and 6 PU patients (6.8%) were HLA-B27 positive; none of the intermediate uveitis (IU) patients exhibited HLA-B27 positivity. HLA-B27, HLA-DR4, and HLA-DRw53 examinations were performed on 40 patients with binocular uveitis, resulting in 2 HLA-B27 positive cases, 15 HLA-DR4 positive cases, and 20 HLA-DRw53 positive cases, with positive rates of 5%, 37.5%, and 50%, respectively. Among 25 Vogt Koyanagi-Harada (VKH) cases, 1 tested positive for HLA-B27, 22 were positive for HLA-DR4, and 24 were positive for HLA-DRw53, with positive rates of 4%, 88%, and 96%, respectively. No positive HLA-B27, HLA-DR4, or HLA-DRw53 cases were found among the 10 cases of Behcet's disease (BD). Conclusions: Human leukocyte antigens (HLAs) play a significant role in the mechanism of uveitis. HLA-B27 exhibits high diagnostic value in acute AU, while HLA-DR4 and HLA-DRw53 are crucial for diagnosing binocular uveitis, particularly Vogt Koyanagi-Harada (VKH) syndrome. Further investigation is warranted to explore the relationship between HLA-DR4, HLA-DRw53, and uveitis.

Autoimmune Diabetes From Childhood to Adulthood: The Role of Pancreatic Autoantibodies and HLA-DRB1 Genotype.

CONTEXT: Autoimmune diabetes can develop at any age, but unlike early-onset diabetes, adult onset is less well documented. We aimed to compare, over a wide age range, the most reliable predictive biomarkers for this pathology: pancreatic-autoantibodies and HLA-DRB1 genotype. METHODS: A retrospective study of 802 patients with diabetes (aged 11 months to 66 years) was conducted. Pancreatic autoantibodies at diagnosis: insulin autoantibodies (IAA), glutamate decarboxylase autoantibodies (GADA), islet tyrosine phosphatase 2 autoantibodies (IA2A), and zinc transporter-8 autoantibodies (ZnT8A) and HLA-DRB1 genotype were analyzed. RESULTS: Compared with early-onset patients, adults had a lower frequency of multiple autoantibodies, with GADA being the most common. At early onset, IAA was the most frequent in those younger than 6 years and correlated inversely with age; GADA and ZnT8A correlated directly and IA2A remained stable.The absence of HLA-DRB1 risk genotype was associated with higher age at diabetes onset (27.5 years; interquartile range [IQR], 14.3-35.7), whereas the high-risk HLA-DR3/DR4 was significantly more common at lower age (11.9 years; IQR, 7.1-21.6). ZnT8A was associated with DR4/non-DR3 (odds ratio [OR], 1.91; 95% CI, 1.15-3.17), GADA with DR3/non-DR4 (OR, 2.97; 95% CI, 1.55-5.71), and IA2A with DR4/non-DR3 and DR3/DR4 (OR, 3.89; 95% CI, 2.28-6.64, and OR, 3.08; 95% CI, 1.83-5.18, respectively). No association of IAA with HLA-DRB1 was found. CONCLUSION: Autoimmunity and HLA-DRB1 genotype are age-dependent biomarkers. Adult-onset autoimmune diabetes is associated with lower genetic risk and lower immune response to pancreatic islet cells compared with early-onset diabetes.

Epicutaneous immunization with TNP-Ig antigen induces CD11c+IL-10+ dendritic cells that promote suppression of Th1-mediated contact hypersensitivity in humanized HLA-DR4 transgenic mice.

The contact hypersensitivity response (CHS) is a mouse model of allergic contact dermatitis in humans. The reaction is classified as type IV hypersensitivity and underlies many autoimmune disorders. Experiments employing the CHS model in wild-type mice showed that the protein antigen applied to the skin in the form of a gauze patch one week before the induction of Th1-dependent CHS was an effective strategy to reduce the inflammatory response in the skin. The approach of epicutaneous (EC) immunization also effectively suppressed the inflammatory response in various mouse models of autoimmune diseases. To evaluate the potential of EC immunization to suppress T cell-dependent immune response in humans, we used HLA-DR4 tg mice, which express the human DRB1*0401 allele and lack all endogenous mouse MHC class II genes. Our data show that EC immunization with TNP-conjugated protein antigen followed by induction of CHS to trinitrochlorobenzene (TNCB), effectively suppressed the CHS response as described by ear swelling, MPO activity in ear extracts, and the number of TCRß+CD4+IFN-γ+ CHS T-effector cells in auxiliary and inguinal lymph nodes (ALN) and spleen (SPL) of HLA-DR4 tg mice. EC-induced suppression increases the frequency of CD11c+IL-10+ DCs in SPL. Their immunoregulatory role was confirmed by s.c. immunization with TNP-CD11c+DCs prior to CHS elicitation and induction. Our data in HLA-DR4 tg mice show that EC protein immunization induces IL-10-producing DCs, which suppress the development of CD4+IFN-γ+ T cell-dependent CHS, implying that EC protein immunization could be of therapeutic importance for T cell-mediated diseases in humans.

Matching for HLA-DR excluding diabetogenic HLA-DR3 and HLA-DR4 predicts insulin independence after pancreatic islet transplantation.

Introduction: In pancreatic islet transplantation, the exact contribution of human leukocyte antigen (HLA) matching to graft survival remains unclear. Islets may be exposed to allogenic rejection but also the recurrence of type 1 diabetes (T1D). We evaluated the HLA-DR matching, including the impact of diabetogenic HLA-DR3 or HLA-DR4 matches. Methods: We retrospectively examined the HLA profile in 965 transplant recipients and 2327 islet donors. The study population was obtained from patients enrolled in the Collaborative Islet Transplant Registry. We then identified 87 recipients who received a single-islet infusion. Islet-kidney recipients, 2nd islet infusion, and patients with missing data were excluded from the analysis (n=878). Results: HLA-DR3 and HLA-DR4 were present in 29.7% and 32.6% of T1D recipients and 11.6% and 15.8% of the donors, respectively. We identified 52 T1D islet recipients mismatched for HLA-DR (group A), 11 with 1 or 2 HLA-DR-matches but excluding HLA-DR3 and HLA- DR4 (group B), and 24 matched for HLA-DR3 or HLA-DR4 (group C). Insulin-independence was maintained in a significantly higher percentage of group B recipients from year one through five post-transplantation (p<0.01). At five-year post-transplantation, 78% of group B was insulin-independent compared to 24% (group A) and 35% (group C). Insulin-independence correlated with significantly better glycemic control (HbA1c <7%), fasting blood glucose, and reduced severe hypoglycemic events. Matching HLA-A-B-DR (≥3) independently of HLA- DR3 or HLA-DR4 matching did not improve graft survival. Conclusion: This study suggests that matching HLA-DR but excluding the diabetogenic HLA-DR3 and/or 4 is a significant predictor for long-term islet survival.

Immune responses to citrullinated and homocitrullinated peptides in healthy donors are not restricted to the HLA SE shared allele and can be selected into the memory pool.

Citrullination and homocitrullination are stress induced post-translational modifications (siPTMs) which can be recognized by T cells. Peripheral blood mononuclear cells isolated from healthy donors and rheumatoid arthritis (RA) patients were stimulated with nine siPTM-peptides. CD45RA/CD45RO depletion was employed to determine if peptide-specific responses are naïve or memory. Human leucocyte antigen (HLA)-DP4 and HLA-DR4 transgenic mice were immunized with siPTM-peptides and immune responses were determined with ex vivo ELISpot assays. The majority (24 out of 25) of healthy donors showed CD4 T cell-specific proliferation to at least 1 siPTM-peptide, 19 to 2 siPTM-peptides, 14 to 3 siPTM-peptides, 9 to 4 siPTM-peptides, 6 to 5 siPTM-peptides and 4 to 6 siPTM-peptides. More donors responded to Vim28-49cit (68%) and Bip189-208cit (75%) compared with Vim415-433cit (33%). In RA patients, the presentation of citrullinated epitopes is associated with HLA-SE alleles; however, we witnessed responses in healthy donors who did not express the SE allele. The majority of responding T cells were effector memory cells with a Th1/cytotoxic phenotype. Responses to Vim28-49cit and Eno241-260cit originated in the memory pool, while the response to Vim415-433cit was naïve. In the HLA-DP4 and HLA-DR4 transgenic models, Vim28cit generated a memory response. Peptide-specific T cells were capable of Epstein-Barr virus transformed lymphoblastoid cell line recognition suggesting a link with stress due to infection. These results suggest siPTM-peptides are presented under conditions of cellular stress and inflammation and drive cytotoxic CD4 T cell responses that aid in the removal of stressed cells. The presentation of such siPTM-peptides is not restricted to HLA-SE in both humans and animal models.

Generation of TGFßR2(-1) neoantigen-specific HLA-DR4-restricted T cell receptors for cancer therapy.

BACKGROUND: Adoptive transfer of patient's T cells, engineered to express a T cell receptor (TCR) with defined novel antigen specificity, is a convenient form of cancer therapy. In most cases, major histocompatibility complex (MHC) I-restricted TCRs are expressed in CD8+ T cells and the development of CD4+ T cells engineered to express an MHC II-restricted TCR lacks behind. Critical is the choice of the target antigen, whether the epitope is efficiently processed and binds with high affinity to MHC molecules. A mutation in the transforming growth factor ß receptor 2 (TGFßR2(-1)) gene creates a frameshift peptide caused by the deletion of one adenine (-1) within a microsatellite sequence. This somatic mutation is recurrent in microsatellite instable colorectal and gastric cancers and, therefore, is a truly tumor-specific antigen detected in many patients. METHODS: ABabDR4 mice, which express a diverse human TCR repertoire restricted to human MHC II molecule HLA-DRA/DRB1*0401 (HLA-DR4), were immunized with the TGFßR2(-1) peptide and TGFßR2(-1)-specific TCRs were isolated from responding CD4+ T cells. The TGFßR2(-1)-specific TCRs were expressed in human CD4+ T cells and their potency and safety profile were assessed by co-cultures and other functional assays. RESULTS: We demonstrated that TGFßR2(-1) neoantigen is immunogenic and elicited CD4+ T cell responses in ABabDR4 mice. When expressed in human CD4+ T cells, the HLA-DR4 restricted TGFßR2(-1)-specific TCRs induced IFNy expression at low TGFßR2(-1) peptide amounts. The TGFßR2(-1)-specific TCRs recognized HLA-DR4+ lymphoblastoid cells, which endogenously processed and presented the neoantigen, and colorectal cancer cell lines SW48 and HCT116 naturally expressing the TGFßR2(-1) mutation. No MHC II alloreactivity or cross-reactivity to peptides with a similar TCR-recognition motif were observed, indicating the safety of the TCRs. CONCLUSIONS: The data suggest that HLA-DR4-restricted TCRs specific for the TGFßR2(-1) recurrent neoantigen can be valuable candidates for adoptive T cell therapy of a sizeable number of patients with cancer.

Rheumatoid factor recognizes specific domains of the IgG heavy chain complexed with HLA class II molecules.

OBJECTIVE: We previously reported that RF recognized the IgG heavy chain (IgGH)/RA-susceptible HLA class II molecule complex. In the present study, we investigated the molecular mechanisms underlying HLA binding to and the RF recognition of IgGH. METHODS: We synthesized various types of IgGH segments, including VH, CH1, CH2 and CH3, and transfected them with or without HLA class II molecules into the Human Embryonic Kidney 293T cell line. IgGH single domains linked with the HLA-Cw3 peptide, which binds to the binding groove of the HLA class II molecule, were also synthesized. The expression of IgGH domains on the cell surface and their recognition by RF were examined using flow cytometry. RESULTS: Flag-tagged IgGH segments containing CH1 (CH1, VH-CH1, CH1-CH2, VH-CH1-CH2, CH1-CH2-CH3 and VH-CH1-CH2-CH3) were clearly presented on the cell surface by HLA-DR4, while segments without the CH1 domain were expressed at a low level, and the CH3 single domain was only weakly detected on the cell surface, even with HLA-DR4. We then transfected IgGH single domains linked to the Cw3 peptide together with HLA-DR4 and showed that RF-containing sera from RA patients only recognized the CH3 domain and none of the other single domains. When various segments without the Cw3 peptide were transfected with HLA-DR4, only the CH1-CH2-CH3 segment and full-length IgGH were detected by the sera of RA patients. CONCLUSION: The CH1 domain of IgGH binds to the RA-susceptible HLA-DR molecule and is expressed on the cell surface. RF specifically recognizes the CH3 domain of the IgGH/HLA-DR4 complex.

DR4/DQ2 haplotype confers susceptibility to T1DM with early clinical disease onset: A retrospective analysis in a tertiary-care hospital in Italy.

INTRODUCTION: T1DM is the most frequent form of diabetes in children. It has a multifactorial pathogenesis in which genetic, environmental and immunological factors are involved. Among genetic explanations a major role is attributed to second class HLA genes, with the greatest risk associated with the simultaneous presence of the haplotypes DR3DQ2 and DR4DQ8. Based on results obtained in other countries, the aim of this research is to verify a possible association between the haplotype DRB1 * 04: 05-DQA1 * 03-DQB1 * 02 and the onset of T1DM among Italian children with possible genotype-phenotype correlations. Greater knowledge of genes which increase or decrease susceptibility is important for genome analysis. MATERIALS AND METHODS: 165 patients with type 1 diabetes treated at the Diabetology Unit of the Meyer Children's University Hospital, were clinically analyzed. Data relating to age at diagnosis, pancreatic anti-beta cell autoimmunity, comorbidities with date of diagnosis and family history were retrospectively collected from medical data. A case-control study was conducted to investigate the HLA types of the patients compared to a control group of 819 Tuscan donors enrolled in the National Bone Marrow Donor Register. Typing was carried out using the Eurospital "DIABEGEN" kit, currently in use at the immunology laboratory of the Meyer Children's University Hospital. RESULTS: Mean age at diagnosis was 9.3 years; most children (97%) had anti-pancreatic beta cell autoimmunity; the anti-insulin antibody (IAA) was more frequent among children with early clinical disease onset (0-5 years of age). From the case control comparison performed on HLA typing, it emerged that the greatest risk for the development of type 1 diabetes is conferred by the haplotypes DR3DQ2 and DR4DQ8, but in addition to these haplotypes, already known in other countries, we identified another haplotype, DR4DQ2 (DRB1 * 04: 05-DQA1 * 03-DQB1 * 02) which appears to predispose children to type 1 diabetes (p value 2.80E-08) and it is associated with early clinical disease onset (p-value = 0.002). CONCLUSIONS: We report a new haplotype which increases susceptibility to type 1 diabetes among Italian children and which is associated with early clinical disease onset. Given the central role attributed to genetic factors in the pathogenesis of T1DM and to the II class HLA genes, this new haplotype ought to be recognized as a risk factor and included in tests routinely carried out to identify patients with a genetic predisposition to type I diabetes in Italy. These findings could have practical implications in research and prevention programs.

Case report: Bilateral panuveitis resembling Vogt-Koyanagi-Harada disease after second dose of BNT162b2 mRNA COVID-19 vaccine.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a serious pandemic. COVID-19 vaccination is urgent needed for limiting SARS-CoV-2 outbreaks by herd immunity. Simultaneously, post-marketing surveillance to assess vaccine safety is important, and collection of vaccine-related adverse events has been in progress. Vision-threatening ophthalmic adverse events of COVID-19 vaccines are rare but are a matter of concern. We report a 45-year-old Japanese male with positive for HLA-DR4/HLA-DRB1*0405, who developed bilateral panuveitis resembling Vogt-Koyanagi-Harada (VKH) disease after the second dose of Pfizer-BioNTech COVID-19 mRNA (BNT162b2) vaccine. Glucocorticosteroid (GC) therapy combined with cyclosporine A (CsA) readily improved the panuveitis. The immune profile at the time of onset was analyzed using CyTOF technology, which revealed activations of innate immunity mainly consisting of natural killer cells, and acquired immunity predominantly composed of B cells and CD8+ T cells. On the other hand, the immune profile in the remission phase was altered by GC therapy with CsA to a profile composed primarily of CD4+ cells, which was considerably similar to that of the healthy control before the vaccination. Our results indicate that BNT162b2 vaccine may trigger an accidental immune cross-reactivity to melanocyte epitopes in the choroid, resulting in the onset of panuveitis resembling VKH disease.

Predictors of the Initiation of Islet Autoimmunity and Progression to Multiple Autoantibodies and Clinical Diabetes: The TEDDY Study.

OBJECTIVE: To distinguish among predictors of seroconversion, progression to multiple autoantibodies and from multiple autoantibodies to type 1 diabetes in young children. RESEARCH DESIGN AND METHODS: Genetically high-risk newborns (n = 8,502) were followed for a median of 11.2 years (interquartile range 9.3-12.6); 835 (9.8%) developed islet autoantibodies and 283 (3.3%) were diagnosed with type 1 diabetes. Predictors were examined using Cox proportional hazards models. RESULTS: Predictors of seroconversion and progression differed, depending on the type of first appearing autoantibody. Male sex, Finnish residence, having a sibling with type 1 diabetes, the HLA DR4 allele, probiotic use before age 28 days, and single nucleotide polymorphism (SNP) rs689_A (INS) predicted seroconversion to IAA-first (having islet autoantibody to insulin as the first appearing autoantibody). Increased weight at 12 months and SNPs rs12708716_G (CLEC16A) and rs2292239_T (ERBB3) predicted GADA-first (autoantibody to GAD as the first appearing). For those having a father with type 1 diabetes, the SNPs rs2476601_A (PTPN22) and rs3184504_T (SH2B3) predicted both. Younger age at seroconversion predicted progression from single to multiple autoantibodies as well as progression to diabetes, except for those presenting with GADA-first. Family history of type 1 diabetes and the HLA DR4 allele predicted progression to multiple autoantibodies but not diabetes. Sex did not predict progression to multiple autoantibodies, but males progressed more slowly than females from multiple autoantibodies to diabetes. SKAP2 and MIR3681HG SNPs are newly reported to be significantly associated with progression from multiple autoantibodies to type 1 diabetes. CONCLUSIONS: Predictors of IAA-first versus GADA-first autoimmunity differ from each other and from the predictors of progression to diabetes.

Correlation of caries occurrence in primary teeth using human leukocyte antigen typing and maternal and physiochemical factors.

Background: Dental caries being the leading health issue worldwide has no specific cure due to its multifactorial etiology and genetic susceptibility. Hence, this paper attempted to correlate the clinical and hereditary factors between mother and child, to predict the caries occurrence in child in future, and thereby implement early preventive measures. Aim: The aim of the study was to look for an association between maternal and child's human leukocyte antigen (HLA)-DR4 levels and relate it with other physiochemical factors to assess caries susceptibility in children. Methodology: Saliva samples were collected from children who were in the age group of 0-6 years and their mothers by spitting method and swab method. The clinical indicators such as Decayed, Missing, and Filled Teeth, decayed, extraction needed, and filled teeth, salivary flow rate, and pH were recorded by clinical evaluation. The Streptococcus mutans count was measured by culture plate followed by colony count method, and the HLA-DR4 factor was assessed using ELISA. Results: The results revealed a statistically significant correlation between the physiochemical factors of the mother and the child. The genetic factor in which the HLA-DR4 caries indicator was checked also has a strong association between the mother and the offspring. Thus, a strong caries prediction formula was derived through which probability of caries occurrence in the child could be determined prematurely. Conclusion: Thus, it can be concluded that using the clinical and genetic factors, the caries prediction can be done for the child and preventive protocol can be started before disease occurrence.

Increased susceptibility to organic dust exposure-induced inflammatory lung disease with enhanced rheumatoid arthritis-associated autoantigen expression in HLA-DR4 transgenic mice.

Immunogenetic as well as environmental and occupational exposures have been linked to the development of rheumatoid arthritis (RA), RA-associated lung disease, and other primary lung disorders. Importantly, various inhalants can trigger post-translational protein modifications, resulting in lung autoantigen expression capable of stimulating pro-inflammatory and/or pro-fibrotic immune responses. To further elucidate gene-environment interactions contributing to pathologic lung inflammation, we exploited an established model of organic dust extract (ODE) exposure with and without collagen-induced arthritis (CIA) in C57BL/6 wild type (WT) versus HLA-DR4 transgenic mice. ODE-induced airway infiltration driven by neutrophils was significantly increased in DR4 versus WT mice, with corresponding increases in bronchoalveolar lavage fluid (BALF) levels of TNF-⍺, IL-6, and IL-33. Lung histopathology demonstrated increased number of ectopic lymphoid aggregates comprised of T and B cells following ODE exposure in DR4 mice. ODE also induced citrullination, malondialdehyde acetaldehyde (MAA) modification, and vimentin expression that co-localized with MAA and was enhanced in DR4 mice. Serum and BALF anti-MAA antibodies were strikingly increased in ODE-treated DR4 mice. Coupling ODE exposure with Type II collagen immunization (CIA) resulted in similarly augmented pro-inflammatory lung profiles in DR4 mice (relative to WT mice) that was accompanied by a profound increase in infiltrating lung CD4+ and CD8+ T cells as well as CD19+CD11b+ autoimmune B cells. Neither modeling strategy induced significant arthritis. These findings support a model in which environmental insults trigger enhanced post-translational protein modification and lung inflammation sharing immunopathological features with RA-associated lung disease in the selected immunogenetic background of HLA-DR4 mice.

PAD2 immunization induces ACPA in wild-type and HLA-DR4 humanized mice.

Rheumatoid arthritis (RA) is associated with HLA-DRB1 alleles expressing the "shared epitope." RA is usually preceded by the emergence of anti-citrullinated protein autoantibodies (ACPAs). ACPAs recognize citrulline residues on numerous proteins. Conversion of arginine into citrulline is performed by enzymes called peptidyl arginine deiminases (PADs). We have previously demonstrated that C3H mice immunized with PADs can produce ACPAs by a hapten-carrier mechanism. Here, we address the influence of HLA-DR alleles in this model in mice expressing RA-associated HLA-DRB1*04:01 (KO/KI*04:01), HLA-DRB1*04:04 (KO/KI*04:04), or non-RA-associated HLA-DRB1*04:02 (KO/KI*04:02) after murine PAD2 immunization. Immunization with mPAD2 triggers production of ACPAs in wild-type (WT) and HLA-DR4 C57BL/6 mice. Both I-Ab and HLA-DR are involved in the activation of mPAD2-specific T lymphocytes. Among HLA-DR4 mice, mice expressing RA-associated HLA-DRB1*04:01 are the best responders to mPAD2 and the best anti-citrullinated peptide antibody producers.

Autoantibodies against ATP4A are a feature of the abundant autoimmunity that develops in first-degree relatives of patients with type 1 diabetes.

OBJECTIVE: Type 1 diabetes is associated with autoantibodies to different organs that include the gut. The objective of the study was to determine the risk of developing gastric parietal cell autoimmunity in relation to other autoimmunity in individuals with a family history of type 1 diabetes. METHODS: Autoantibodies to the parietal cell autoantigen, H+ /K+ ATPase subunit A (ATP4A) was measured in 2218 first-degree relatives of patients with type 1 diabetes, who were prospectively followed from birth for a median of 14.5 years. All were also tested regularly for the development of islet autoantibodies, transglutaminase autoantibodies, and thyroid peroxidase autoantibodies. RESULTS: The cumulative risk to develop ATP4A autoantibodies was 8.1% (95% CI, 6.6-9.6) by age 20 years with a maximum incidence observed at age 2 years. Risk was increased in females (HR, 1.9; 95% CI, 1.3-2.8; p = 0.0004), relatives with the HLA DR4-DQ8/DR4-DQ8 genotype (HR, 3.4; 95% CI, 1.9-5.9; p < 0.0001) and in participants who also had thyroid peroxidase autoantibodies (HR, 3.7; 95% CI, 2.5-5.5; p < 0.0001). Risk for at least one of ATP4A-, islet-, transglutaminase-, or thyroid peroxidase-autoantibodies was 24.7% (95% CI, 22.6-26.7) by age 20 years and was 47.3% (95% CI, 41.3-53.3) in relatives who had an HLA DR3/DR4-DQ8, DR4-DQ8/DR4-DQ8, or DR3/DR3 genotype (p < 0.0001 vs. other genotypes). CONCLUSIONS: Relatives of patients with type 1 diabetes who have risk genotypes are at very high risk for the development of autoimmunity against gastric and other organs.