Transcriptomic analysis of intestine following administration of a transglutaminase 2 inhibitor to prevent gluten-induced intestinal damage in celiac disease.

Transglutaminase 2 (TG2) plays a pivotal role in the pathogenesis of celiac disease (CeD) by deamidating dietary gluten peptides, which facilitates antigenic presentation and a strong anti-gluten T cell response. Here, we elucidate the molecular mechanisms underlying the efficacy of the TG2 inhibitor ZED1227 by performing transcriptional analysis of duodenal biopsies from individuals with CeD on a long-term gluten-free diet before and after a 6-week gluten challenge combined with 100 mg per day ZED1227 or placebo. At the transcriptome level, orally administered ZED1227 effectively prevented gluten-induced intestinal damage and inflammation, providing molecular-level evidence that TG2 inhibition is an effective strategy for treating CeD. ZED1227 treatment preserved transcriptome signatures associated with mucosal morphology, inflammation, cell differentiation and nutrient absorption to the level of the gluten-free diet group. Nearly half of the gluten-induced gene expression changes in CeD were associated with the epithelial interferon-γ response. Moreover, data suggest that deamidated gluten-induced adaptive immunity is a sufficient step to set the stage for CeD pathogenesis. Our results, with the limited sample size, also suggest that individuals with CeD might benefit from an HLA-DQ2/HLA-DQ8 stratification based on gene doses to maximally eliminate the interferon-γ-induced mucosal damage triggered by gluten.

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.

IL-15, gluten and HLA-DQ8 drive tissue destruction in coeliac disease.

Coeliac disease is a complex, polygenic inflammatory enteropathy caused by exposure to dietary gluten that occurs in a subset of genetically susceptible individuals who express either the HLA-DQ8 or HLA-DQ2 haplotypes1,2. The need to develop non-dietary treatments is now widely recognized3, but no pathophysiologically relevant gluten- and HLA-dependent preclinical model exists. Furthermore, although studies in humans have led to major advances in our understanding of the pathogenesis of coeliac disease4, the respective roles of disease-predisposing HLA molecules, and of adaptive and innate immunity in the development of tissue damage, have not been directly demonstrated. Here we describe a mouse model that reproduces the overexpression of interleukin-15 (IL-15) in the gut epithelium and lamina propria that is characteristic of active coeliac disease, expresses the predisposing HLA-DQ8 molecule, and develops villous atrophy after ingestion of gluten. Overexpression of IL-15 in both the epithelium and the lamina propria is required for the development of villous atrophy, which demonstrates the location-dependent central role of IL-15 in the pathogenesis of coeliac disease. In addition, CD4+ T cells and HLA-DQ8 have a crucial role in the licensing of cytotoxic T cells to mediate intestinal epithelial cell lysis. We also demonstrate a role for the cytokine interferon-γ (IFNγ) and the enzyme transglutaminase 2 (TG2) in tissue destruction. By reflecting the complex interaction between gluten, genetics and IL-15-driven tissue inflammation, this mouse model provides the opportunity to both increase our understanding of coeliac disease, and develop new therapeutic strategies.

Interchain disulfide engineering enables the efficient production of functional HLA-DQ-Fc fusion proteins.

HLA-DQ molecules drive unwanted alloimmune responses after solid-organ transplants and several autoimmune diseases, including type 1 diabetes and celiac disease. Biologics with HLA molecules as part of the design are emerging therapeutic options for these allo- and autoimmune conditions. However, the soluble α and ß chains of class II HLA molecules do not dimerize efficiently without their transmembrane domains, which hinders their production. In this study, we examined the feasibility of interchain disulfide engineering by introducing paired cysteines to juxtaposed positions in the α and ß chains of HLA-DQ7, encoded by HLA-DQA1∗05:01 and HLA-DQB1∗03:01 respectively. We identified three variant peptide-HLA-DQ7-Fc fusion proteins (DQ7Fc) with increased expression and production yield, namely Y19C-D6C (YCDC), A83C-E5C (ACEC), and A84C-N33C (ACNC). The mutated residues were conserved across all HLA-DQ proteins and had limited solvent exposure. Further characterizations of the YCDC variant showed that the expression of the fusion protein is peptide-dependent; inclusion of a higher-affinity peptide correlated with increased protein expression. However, high-affinity peptide alone was insufficient for stabilizing the DQ7 complex without the engineered disulfide bond. Multiple DQ7Fc variants demonstrated expected binding characteristics with commercial anti-DQ antibodies in two immunoassays and by a cell-based assay. Lastly, DQ7Fc variants demonstrated dose-dependent killing of DQ7-specific B cell hybridomas in a flow cytometric, complement-dependent cytotoxicity assay. These data support inter-chain disulfide engineering as a novel approach to efficiently producing functional HLA-DQ molecules and potentially other class II HLA molecules as candidate therapeutic agents.

A structural basis of T cell cross-reactivity to native and spliced self-antigens presented by HLA-DQ8.

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease that has a strong HLA association, where a number of self-epitopes have been implicated in disease pathogenesis. Human pancreatic islet-infiltrating CD4+ T cell clones not only respond to proinsulin C-peptide (PI40-54; GQVELGGGPGAGSLQ) but also cross-react with a hybrid insulin peptide (HIP; PI40-47-IAPP74-80; GQVELGGG-NAVEVLK) presented by HLA-DQ8. How T cell receptors recognize self-peptide and cross-react to HIPs is unclear. We investigated the cross-reactivity of the CD4+ T cell clones reactive to native PI40-54 epitope and multiple HIPs fused at the same N-terminus (PI40-54) to the degradation products of two highly expressed pancreatic islet proteins, neuropeptide Y (NPY68-74) and amyloid polypeptide (IAPP23-29 and IAPP74-80). We observed that five out of the seven selected SKW3 T cell lines expressing TCRs isolated from CD4+ T cells of people with T1D responded to multiple HIPs. Despite shared TRAV26-1-TRBV5-1 gene usage in some T cells, these clones cross-reacted to varying degrees with the PI40-54 and HIP epitopes. Crystal structures of two TRAV26-1+-TRBV5-1+ T cell receptors (TCRs) in complex with PI40-54 and HIPs bound to HLA-DQ8 revealed that the two TCRs had distinct mechanisms responsible for their differential recognition of the PI40-54 and HIP epitopes. Alanine scanning mutagenesis of the PI40-54 and HIPs determined that the P2, P7, and P8 residues in these epitopes were key determinants of TCR specificity. Accordingly, we provide a molecular basis for cross-reactivity towards native insulin and HIP epitopes presented by HLA-DQ8.

Diagnosis of Seronegative and Ultrashort Celiac Disease.

In its conventional form, celiac disease (CeD) is characterized by both positive serology and flat villi in the duodenum, and is well known by gastroenterologists and general practitioners. The aim of this review was to shed light on 2 neglected and not yet well-defined celiac phenotypes, that is, seronegative and ultrashort CeD. Seronegative CeD can be suspected in the presence of flat villi, positive HLA-DQ2 and/or HLA-DQ8, and the absence of CeD antibodies. After ruling out other seronegative enteropathies, the diagnosis can be confirmed by both clinical and histologic improvements after 1 year of a gluten-free diet. Ultrashort CeD is characterized by the finding of flat villi in the duodenal bulb in the absence of mucosal damage in the distal duodenum and with serologic positivity. Data on the prevalence, clinical manifestations, histologic lesions, genetic features, and outcome of seronegative and ultrashort CeD are inconclusive due to the few studies available and the small number of patients diagnosed. Some additional diagnostic tools have been developed recently, such as assessing intestinal transglutaminase 2 deposits, flow cytometry technique, microRNA detection, or proteomic analysis, and they seem to be useful in the identification of complex cases. Further cooperative studies are highly desirable to improve the knowledge of these 2 still-obscure variants of CeD.

Investigating associations between HLA DQA1 ~ DQB1 haplotypes, H. pylori infection, metaplasia, and anti-CagA IgA seropositivity in a Turkish gastritis cohort.

Helicobacter pylori was reported as an important cause of gastritis, and gastric ulcers and CagA oncoprotein-producing H. pylori subgroups were blamed to increase the severity of gastritis. Disparities were reported in that the presence of serum anti-CagA IgA was not parallel with CagA-positive H. pylori cohabitation. We hypothesized that the HLA-DQA1 ~ DQB1 haplotypes in human populations include protective haplotypes that more effectively present immunogenic CagA peptides and susceptible haplotypes with an impaired capacity to present CagA peptides. We recruited patients (n = 201) admitted for gastroendoscopy procedures and performed high-resolution HLA-DQA1 and DQB1 typing. Serum anti-CagA IgA levels were analyzed by ELISA (23.0% positive), and H. pylori was classified as positive or negative in gastric mucosal tissue slides (72.6% positive). The HLA DQA1*05:05 allele (29.1%) and HLA DQB1*03:01 allele (32.8%) were found at the highest frequency among gastritis patients of Turkish descent. In HLA DQA1*05:05 ~ DQB1*03:01 double homozygous (7.3%) and heterozygous (40.7%) haplotype carriers, the presence of anti-CagA IgA decreased dramatically, the presence of H. pylori increased, and the presence of metaplasia followed a decreasing trend. The DQ protein encoded by HLA DQA1*05:05-DQ*03:01 showed a low binding affinity to the CagA peptide when binding capacity was analyzed by the NetMHCIIPan 4.0 prediction method. In conclusion, HLA DQA1 ~ DQB1 polymorphisms are crucial as host defense mechanisms against CagA H. pylori since antigen binding capacity plays a crucial role in anti-CagA IgA production.

Functional metagenomic analysis reveals potential inflammatory triggers associated with genetic risk for autoimmune disease.

To assess functional differences between the microbiomes of individuals with autoimmune risk-associated human leukocyte antigen (HLA) genetics and autoimmune protection-associated HLA, we performed a metagenomic analysis of stool samples from 72 infants in the All Babies in Southeast Sweden general-population cohort and assessed haplotype-peptide binding affinities. Infants with risk-associated HLA DR3-DQ2.5 and DR4-DQ8 had a higher abundance of known pathogen-associated molecular patterns and virulence related genes than infants with protection-associated HLA DR15-DQ6.2. However, there was limited overlap in the type of inflammatory trigger between risk groups. Supported by a high Firmicutes/Bacteroides ratio and differentially abundant flagellated species, genes related to the synthesis of flagella were prominent in those with HLA DR3-DQ2.5. However, this haplotype had a significantly lower likelihood of binding affinity to flagellin peptides. O-antigen biosynthesis genes were significantly correlated with the risk genotypes and absent from protective genotype association, supported by the differential abundance of gram-negative bacteria seen in the risk-associated groups. Genes related to vitamin B biosynthesis stood out in higher abundance in infants with HLA DR3-DQ2.5/DR4-DQ8 heterozygosity compared to those with autoimmune-protective genetics. Prevotella species and genus were significantly abundant in all infant groups with high risk for autoimmune disease. The potential inflammatory triggers associated with genetic risk for autoimmunity have significant implications. These results suggest that certain HLA haplotypes may be creating the opportunity for dysbiosis and subsequent inflammation early in life by clearing beneficial microbes or not clearing proinflammatory microbes. This HLA gatekeeping may prevent genetically at-risk individuals from benefiting from probiotic therapies by restricting the colonization of those beneficial bacteria.

HLA-DQ heterodimers in hematopoietic cell transplantation.

HLA-DQ heterodimers increase the susceptibility to autoimmune diseases, but their role in hematopoietic cell transplantation is unknown. We tested the hypothesis that outcome after HLA-matched and HLA-DQ-mismatched hematopoietic cell transplantation is influenced by HLA-DQ heterodimers. Heterodimers were defined in 5164 HLA-matched and 520 HLA-DQ-mismatched patients and their transplant donors according to well-established crystallographic criteria. Group 1 (G1) heterodimers are any DQA1*02/03/04/05/06α paired with any DQB1*02/03/04ß. Group 2 (G2) heterodimers are DQA1*01α paired with any DQB1*05/06ß. Multivariable models identified significantly higher relapse risk in G1G2 and G2G2 compared with G1G1 HLA-matched patients with malignant disease; risk increased with an increasing number of G2 molecules. In HLA-DQ-mismatched transplantation for malignant diseases, matching or mismatching for G2 increased relapse risk. G2 lowered disease-free survival after both HLA-matched and HLA-DQ-mismatched transplantation. A paradigm based on HLA-DQ heterodimers provides a functional definition of the hematopoietic cell transplantation barrier and a means to lower risks for future patients.

Diagnosing celiac disease in children using oral manifestations.

PURPOSE: Celiac disease (CD) may be frequently undiagnosed due to the absence of characteristic gastroenterologic symptoms in many CD patients. Our objective was to diagnose CD by utilizing documented oral manifestations such as Recurrent Aphthous Stomatitis (RAS) and Molar-Incisor Hypomineralization (MIH). METHODS: The study comprised sixty children who presented with complaints of RAS lesions. The MIH group consisted of 40 children, while the control group comprised 20 children without MIH lesions, ranging in age from 7 to 13 years. After the dental examination, all children were given a questionnaire to assess whether they had any previous history of general symptoms related to CD. Following that, diagnostic testing for celiac disease were conducted, including serological tests such as Tissue transglutaminase IgA (tTG-IgA), Endomysium Antibody (EMA), and Total IgA, as well as genetic tests for HLA-DQ2 and HLA-DQ8. RESULTS: The statistical analysis, conducted using Fisher's Exact, Yates' Continuity Correction, Fisher Freeman Halton, and Student's t tests, revealed no significant differences between the groups (p < 0.05). Within the MIH group, 3 children exhibited border tTG-IgA values, while another 3 had positive tTG-IgA results. Two of these 6 children had also positive EMA and HLA results. Following a biopsy procedure, these two children were ultimately diagnosed with celiac disease (CD). CONCLUSIONS: In this study, while children initially presented to the clinic with complaints of recurrent aphthous stomatitis (RAS), 2 children (5% of the MIH group) were diagnosed with CD shortly after the onset of MIH lesions. CD enhanced the likelihood of observing some oral manifestations particularly recurrent aphtous stomatitis and developmental enamel defects. We recommend that dentists be cautious about diagnosing CD when RAS lesions and DEDs and/or MIH lesions are present, whether or not other indications of this systemic disease exist.

Genotypes predisposing for celiac disease and autoimmune diabetes and risk of infections in early childhood.

OBJECTIVES: Infections in early childhood have been associated with risk of celiac disease (CD) and type 1 diabetes (T1D). We investigated whether this is driven by susceptibility genes for autoimmune disease by comparing infection frequency by genetic susceptibility variants for CD or T1D. METHODS: We genotyped 373 controls and 384 children who developed CD or T1D in the population-based Norwegian Mother, Father and Child Cohort study (MoBa) study for human leukocyte antigen (HLA)-DQ, FUT2, SH2B3, and PTPN22, and calculated a weighted non-HLA genetic risk score (GRS) for CD and T1D based on over 40 SNPs. Parents reported infections in questionnaires when children were 6 and 18 months old. We used negative binomial regression to estimate incidence rate ratio (IRR) for infections by genotype. RESULTS: HLA genotypes for CD and T1D or non-HLA GRS for T1D were not associated with infections. The non-HLA GRS for CD was associated with a nonsignificantly lower frequency of infections (aIRR: 0.95, 95% CI: 0.87-1.03 per weighted allele score), and significantly so when restricting to healthy controls (aIRR: 0.89, 0.81-0.99). Participants homozygous for rs601338(A;A) at FUT2, often referred to as nonsecretors, had a nonsignificantly lower risk of infections (aIRR: 0.91, 95% CI: 0.83-1.01). SH2B3 and PTPN22 genotypes were not associated with infections. The association between infections and risk of CD (OR: 1.15 per five infections) was strengthened after adjustment for HLA genotype and non-HLA GRS (OR: 1.24). CONCLUSIONS: HLA variants and non-HLA GRS conferring susceptibility for CD were not associated with increased risk of infections in early childhood and is unlikely to drive the observed association between infections and risk of CD or T1D in many studies.

Longitudinal screening of HLA-risk and HLA-nonrisk children for celiac disease to age 15 years: CiPiS study.

OBJECTIVES: Autoantibodies against tissue transglutaminase (tTG) are serological markers of celiac disease. The aim was to study the applicability of human leukocyte antigen (HLA)-genotyping and tTG autoantibodies in the screening of celiac disease in a longitudinal birth cohort followed to age 15 years. METHODS: Included were 13,860 HLA-DQ-genotyped children at birth and previously invited to a screening at age 3 and 9 years, respectively. HLA-DQB1*02 and/or DQB1*03:02 (HLA-risk) children were compared with non-HLA-DQB1*02 and non-DQB1*03:02 (HLA-nonrisk) children. The present study reinvited 12,948/13,860 (93.4%) children at age 15 years of whom 1056/2374 (44.5%) participated in screening at both age 3 and 9 years. Both immunoglobulin A (IgA) and G (IgG) autoantibodies against tTG were analyzed separately in radiobinding assays. Persistently tTG autoantibody-positive children were examined with intestinal biopsy to confirm the diagnosis of celiac disease. RESULTS: At age 3 years, celiac disease was diagnosed in 56/1635 (3.4%) HLA-risk children compared with 0/1824 HLA-nonrisk children (p < 0.001). By age 9 years, celiac disease was diagnosed in 72/1910 (3.8%) HLA-risk children compared with 0/2167 HLA-nonrisk children (p < 0.001). Screening at age 15 years detected 14/1071 (1.3%) HLA-risk children positive for IgA-tTG and/or IgG-tTG of whom 12/1071 (1.1%) remained persistently positive. Among those, 10/1071 (0.9%, 95% confidence interval: 0.4%-1.7%) HLA-risk children were diagnosed with celiac disease compared with 0/1303 HLA-nonrisk children (p < 0.001) and 5/491 (1.0%) were negative in screenings at both 3 and 9 years of age. CONCLUSIONS: Screening for celiac disease needs to be performed at multiple timepoints to detect all cases but can be restricted to children at HLA-risk.

UK NEQAS and BSHI guideline: Laboratory testing and clinical interpretation of HLA genotyping results supporting the diagnosis of coeliac disease.

Coeliac disease is a common immune-mediated inflammatory disorder caused by dietary gluten in genetically susceptible individuals. While the diagnosis of coeliac disease is based on serological and histological criteria, HLA-DQ genotyping can be useful, especially in excluding the diagnosis in patients who do not carry the relevant DQ heterodimers: DQA1*05 DQB1*02, DQB1*03:02 or DQA1*02 DQB1*02 (commonly referred to as DQ2.5, DQ8 and DQ2.2, respectively). External quality assessment results for HLA genotyping in coeliac disease have revealed concerning errors in HLA genotyping, reporting and clinical interpretation. In response, these guidelines have been developed as an evidence-based approach to guide laboratories undertaking HLA genotyping for coeliac disease and provide recommendations for reports to standardise and improve the communication of results.

HLA-DR and HLA-DQ Polymorphism Correlation with Sexually Transmitted Infection Caused by Chlamydia trachomatis.

Background and Objectives: Chlamydia trachomatis (C. trachomatis) represents one of the most prevalent bacterial sexually transmitted diseases. This study aims to explore the relationship between HLA alleles/genotypes/haplotypes and C. trachomatis infection to better understand high-risk individuals and potential complications. Materials and Methods: This prospective study recruited participants from Transylvania, Romania. Patients with positive NAAT tests for C. trachomatis from cervical/urethral secretion or urine were compared with controls regarding HLA-DR and -DQ alleles. DNA extraction for HLA typing was performed using venous blood samples. Results: Our analysis revealed that the presence of the DRB1*13 allele significantly heightened the likelihood of C. trachomatis infection (p = 0.017). Additionally, we observed that individuals carrying the DRB1*01/DRB1*13 and DQB1*03/DQB1*06 genotype had increased odds of C. trachomatis infection. Upon adjustment, the association between the DRB1*01/DRB1*13 genotype and C. trachomatis remained statistically significant. Conclusions: Our findings underscore the importance of specific HLA alleles and genotypes in influencing susceptibility to C. trachomatis infection. These results highlight the intricate relationship between host genetics and disease susceptibility, offering valuable insights for targeted prevention efforts and personalized healthcare strategies.

Transethnic analysis of the human leukocyte antigen region for ulcerative colitis reveals not only shared but also ethnicity-specific disease associations.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gut. Genetic association studies have identified the highly variable human leukocyte antigen (HLA) region as the strongest susceptibility locus for IBD and specifically DRB1*01:03 as a determining factor for ulcerative colitis (UC). However, for most of the association signal such as delineation could not be made because of tight structures of linkage disequilibrium within the HLA. The aim of this study was therefore to further characterize the HLA signal using a transethnic approach. We performed a comprehensive fine mapping of single HLA alleles in UC in a cohort of 9272 individuals with African American, East Asian, Puerto Rican, Indian and Iranian descent and 40 691 previously analyzed Caucasians, additionally analyzing whole HLA haplotypes. We computationally characterized the binding of associated HLA alleles to human self-peptides and analyzed the physicochemical properties of the HLA proteins and predicted self-peptidomes. Highlighting alleles of the HLA-DRB1*15 group and their correlated HLA-DQ-DR haplotypes, we not only identified consistent associations (regarding effects directions/magnitudes) across different ethnicities but also identified population-specific signals (regarding differences in allele frequencies). We observed that DRB1*01:03 is mostly present in individuals of Western European descent and hardly present in non-Caucasian individuals. We found peptides predicted to bind to risk HLA alleles to be rich in positively charged amino acids. We conclude that the HLA plays an important role for UC susceptibility across different ethnicities. This research further implicates specific features of peptides that are predicted to bind risk and protective HLA proteins.

HLA DQ protein changes the cell surface distribution pattern of HLA proteins as monitored by Förster resonance energy transfer and high-resolution electron microscopy.

Peptide presentation by MHC class I and MHC class II molecules plays important roles in the regulation of the immune response. One factor in these displays is the density of antigen, which must exceed a critical threshold for the effective activation of T cells. Nonrandom distribution of MHC class I and class II has already been detected at the nanometer level and at higher hierarchical levels. It is not clear how the absence and reappearance of some protein molecules can influence the nonrandom distribution. Therefore, we performed experiments on HLA II-deficient bare lymphocyte syndrome (BLS1) cells: we created a stable transfected cell line, tDQ6-BLS-1, and were able to detect the effect of the appearance of HLA-DQ6 molecules on the homo and heteroassociation of different cell surface molecules by comparing Förster resonance energy transfer (FRET) efficiency on transfected cells to that on nontransfected BLS-1 and JY human B-cell lines. Our FRET results show a decrease in homoassociation FRET between HLA I chains in HLA-DQ6-transfected tDQ6-BLS-1 cells compared with the parent BLS-1 cell line and an increase in heteroassociation FRET between HLA I and HLA II (compared with JY cells), suggesting a similar pattern of antigen presentation by the HLA-DQ6 allele. Transmission electron microscopy (TEM) revealed that both HLA class I and class II molecules formed clusters at higher hierarchical levels on the tDQ6-BLS-1 cells, and the de novo synthesized HLA DQ molecules did not intersperse with HLA class I islands. These observations could be important in understanding the fine tuning of the immune response.

HLA-DQ-conferred risk for type 1 diabetes does not alter neutralizing antibody response to a widely used enterovirus vaccine, the poliovirus vaccine.

This study investigated whether children with HLA-DQ-conferred risk for type 1 diabetes (T1D) have an altered immune response to the widely-used enterovirus vaccine, namely poliovirus vaccine, and whether initiation of autoimmunity to pancreatic islets modulates this response. Neutralizing antibodies induced by the inactivated poliovirus vaccine against poliovirus type 1 (Salk) were analysed as a marker of protective immunity at the age of 18 months in a prospective birth cohort. No differences were observed in antibody titers between children with and without genetic risk for T1D (odds ratio [OR] = 0.90 [0.83, 1.06], p = 0.30). In the presence of the genetic risk, no difference was observed between children with and without islet autoimmunity (OR = 1.00 [0.78, 1.28], p = 1.00). This did not change when only children with the autoimmunity before 18 months of age were included in the analyses (OR = 1.00 [0.85, 1.18], p = 1.00). No effect was observed when groups were stratified based on autoantigen specificity of the first-appearing autoantibody (IAA or GADA). The children in each comparison group were matched for sex, calendar year and month of birth, and municipality. Accordingly, we found no indication that children who are at risk to develop islet autoimmunity would have a compromised humoral immune response which could have increased their susceptibility for enterovirus infections. In addition, the proper immune response supports the idea of testing novel enterovirus vaccines for the prevention of T1D among these individuals.

HLA-DQ genotype distribution and risk evaluation of celiac disease in Northwest China.

BACKGROUND: Celiac disease (CD) is an autoimmune small bowel disease. Genetic susceptibility for CD is mainly determined by the human leukocyte antigen (HLA)-DQ haplotypes. The risk of CD conferred by HLA genotypes varies geographically and across populations, however, this has not yet been documented in Chinese patients with CD. AIMS: To investigate the distribution of HLA-DQ and the related risks of CD development in Northwest China. METHODS: A total of 75 CD patients and 300 healthy individuals were genotyped for HLA-DQ using the Illumina NextSeq, and the relative risks of the different genotypes were evaluated. RESULTS: In total, 68.00% of CD patients and 21.00% of controls carried HLA-DQ2.5 heterodimers (p < 0.001). We identified four CD risk gradients. Individuals carrying a double dose of DQB1*02 had the highest risk of developing CD (1:16); however, with heterozygosis (DQB1*02:02/DQB1*02:01) having the highest risk (1:9). HLA-DQ2.5 individuals with a single copy of HLA-DQB1*02, in either the cis or trans configuration, were at a medium risk (1:38). Non-DQ2.5 carriers of DQ8 or DQ2.2 were at low risk, while only carriers of DQ7.5 or DQX.5 were at very low risk. Patients with the HLA-DQ2.5 genotype had more severe mucosal damage compared with the HLA-DQ2.5 genotype negative CD patients (70.59% vs. 41.67%, p = 0.016). CONCLUSION: Genetic susceptibility to CD is highly prevalent in the Northwest Chinese population and the highest risk of developing CD was associated with the DQ2.5/DQ2.2 genotype. The DQ2.5 allele is involved in the severity of mucosal injury.

A molecular basis for the T cell response in HLA-DQ2.2 mediated celiac disease.

The highly homologous human leukocyte antigen (HLA)-DQ2 molecules, HLA-DQ2.5 and HLA-DQ2.2, are implicated in the pathogenesis of celiac disease (CeD) by presenting gluten peptides to CD4+ T cells. However, while HLA-DQ2.5 is strongly associated with disease, HLA-DQ2.2 is not, and the molecular basis underpinning this differential disease association is unresolved. We here provide structural evidence for how the single polymorphic residue (HLA-DQ2.5-Tyr22α and HLA-DQ2.2-Phe22α) accounts for HLA-DQ2.2 additionally requiring gluten epitopes possessing a serine at the P3 position of the peptide. In marked contrast to the biased T cell receptor (TCR) usage associated with HLA-DQ2.5-mediated CeD, we demonstrate with extensive single-cell sequencing that a diverse TCR repertoire enables recognition of the immunodominant HLA-DQ2.2-glut-L1 epitope. The crystal structure of two CeD patient-derived TCR in complex with HLA-DQ2.2 and DQ2.2-glut-L1 (PFSEQEQPV) revealed a docking strategy, and associated interatomic contacts, which was notably distinct from the structures of the TCR:HLA-DQ2.5:gliadin epitope complexes. Accordingly, while the molecular surfaces of the antigen-binding clefts of HLA-DQ2.5 and HLA-DQ2.2 are very similar, differences in the nature of the peptides presented translates to differences in responding T cell repertoires and the nature of engagement of the respective antigen-presenting molecules, which ultimately is associated with differing disease penetrance.

Specific Genetic Polymorphisms Contributing in Differential Binding of Gliadin Peptides to HLA-DQ and TCR to Elicit Immunogenicity in Celiac Disease.

Immunogenicity of gliadin peptides in celiac disease (CD) is majorly determined by the pattern of molecular interactions with HLA-DQ and T-cell receptors (TCR). Investigation of the interactions between immune-dominant gliadin peptides, DQ protein, and TCR are warranted to unravel the basis of immunogenicity and variability contributed by the genetic polymorphisms. Homology modeling of HLA and TCR done using Swiss Model and iTASSER, respectively. Molecular interactions of eight common deamidated immune-dominant gliadin with HLA-DQ allotypes and specific TCR gene pairs were evaluated. Docking of the three structures was performed with ClusPro2.0 and ProDiGY was used to predict binding energies. Effects of known allelic polymorphisms and reported susceptibility SNPs were predicted on protein-protein interactions. CD susceptible allele, HLA-DQ2.5 was shown to have considerable binding affinity to 33-mer gliadin (ΔG = - 13.9; Kd = 1.5E - 10) in the presence of TRAV26/TRBV7. Higher binding affinity was predicted (ΔG = - 14.3, Kd = 8.9E - 11) when TRBV28 was replaced with TRBV20 paired with TRAV4 suggesting its role in CD predisposition. SNP rs12722069 at HLA-DQ8 that codes Arg76α forms three H-bonds with Glu12 and two H-bonds with Asn13 of DQ2 restricted gliadin in the presence of TRAV8-3/TRBV6. None of the HLA-DQ polymorphisms was found to be in linkage disequilibrium with reported CD susceptibility markers. Haplotypic presentations of rs12722069-G, rs1130392-C, rs3188043-C and rs4193-A with CD reported SNPs were observed in sub-ethnic groups. Highly polymorphic sites of HLA alleles and TCR variable regions could be utilized for better risk prediction models in CD. Therapeutic strategies by identifying inhibitors or blockers targeting specific gliadin:HLA-DQ:TCR binding sites could be investigated.