Peptide-based molecular analyses of HLA class II-associated susceptibility to autoimmune diseases

Clinical and HLA genotype analysis of immune checkpoint inhibitor-associated diabetes mellitus: a single-center case series from China

Objective

To investigate the clinical characteristics and HLA genotypes of patients with immune checkpoint inhibitor-associated diabetes mellitus (ICI-DM) in China.

Methods

We enrolled 23 patients with ICI-DM and 51 patients with type 1 diabetes (T1D). Clinical characteristics of the patients were collected. HLA-DRB1, HLA-DQA1, and HLA-DQB1 genotyping was conducted via next-generation sequencing.

Results

The ICI-DM patients had a male predominance (70.6%), a mean body mass index (BMI) of 21.2 ± 3.5 kg/m², and a mean onset of ICI-DM in 5 (IQR, 3-9) cycles after ICI therapy. Most (78.3%) ICI-DM patients were treated with anti-PD-1, 78.3% presented with diabetic ketoacidosis, and all had low C-peptide levels and received multiple insulin injections. Compared to T1D patients, ICI-DM patients were significantly older (57.2 ± 12.4 vs 34.1 ± 15.7 years) and had higher blood glucose but lower HbA1c levels (P<0.05). Only two (8.7%) ICI-DM patients were positive for islet autoantibodies, which was lower than that in T1D patients (66.7%, P<0.001). A total of 59.1% (13/22) of ICI-DM patients were heterozygous for an HLA T1D risk haplotype, and DRB1*0901-DQA1*03-DQB1*0303 (DR9) and DRB1*0405-DQA1*03-DQB1*0401 were the major susceptible haplotypes. Compared to T1D, the susceptible DR3-DQA1*0501-DQB1*0201 (DR3) and DR9 haplotypes were less frequent (17.7% vs 2.3%; P=0.011 and 34.4% vs 15.9%; P=0.025), whereas the protective haplotypes (DRB1*1101-DQA1*05-DQB1*0301 and DRB1*1202-DQA1*0601-DQB1*0301) were more frequent in ICI-DM patients (2.1% vs 13.6%; P=0.006 and 4.2% vs 15.9%; P=0.017). None of the ICI-DM patients had T1D-associated high-risk genotypes DR3/DR3, DR3/DR9, and DR9/DR9. Among the 23 ICI-DM patients, 7 (30.4%) presented with ICI-associated fulminant type 1 diabetes (IFD), and 16 (69.6%) presented with ICI-associated type 1 diabetes (IT1D). Compared to IT1D patients, IFD patients exhibited marked hyperglycemia and low C-peptide and HbA1c levels (P<0.05). Up to 66.7% (4/6) of IFD patients were heterozygous for reported fulminant type 1 diabetes susceptibility HLA haplotypes (DRB1*0405-DQB1*0401 or DRB1*0901-DQB1*0303).

Conclusion

ICI-DM shares similar clinical features with T1D, such as acute onset, poor islet function and insulin dependence. However, the lack of islet autoantibodies, the low frequencies of T1D susceptibility and high frequencies of protective HLA haplotypes indicate that ICI-DM represents a new model distinct from classical T1D.

Where, How, and When: Positioning Posttranslational Modification Within Type 1 Diabetes Pathogenesis

Autoreactive T cells specific for islet autoantigens develop in type 1 diabetes (T1D) by escaping central as well as peripheral tolerance. The current paradigm for development of islet autoimmunity is just beginning to include the contribution of posttranslationally modified (PTM) islet autoantigens, for which the immune system may be ignorant rather than tolerant. As a result, PTM is the latest promising lead in the quest to understand how the break in peripheral tolerance occurs in T1D. However, it is not completely clear how, where, or when these modifications take place. Currently, only a few PTM antigens have been well-thought-out or identified in T1D, and methods for identifying and characterizing new PTM antigens are rapidly improving. This review will address both reported and potential new sources of modified islet autoantigens and discuss how islet neo-autoantigen generation may contribute to the development and progression of T1D.

Glutamic acid decarboxylase 65 and islet cell antigen 512/IA-2 autoantibodies in relation to human leukocyte antigen class II DR and DQ alleles and haplotypes in type 1 diabetes mellitus

The frequencies of autoantibodies against glutamic acid decarboxylase 65 (GAD65) and islet cell antigen (ICA) 512/IA-2 (512/IA-2) are functions of the specific human leukocyte antigen (HLA) in type 1 diabetes mellitus (T1D). We investigated the association of HLA class II (DR and DQ) alleles and haplotypes with the presence of GAD and IA-2 autoantibodies in T1D. Autoantibodies were tested in 88 Tunisian T1D patients and 112 age- and gender-matched normoglycemic control subjects by enzyme immunoassay. Among T1D patients, mean anti-GAD antibody titers were higher in the DRB1*030101 allele (P < 0.001), together with the DRB1*030101/DQB1*0201 (P < 0.001) and DRB1*040101/DQB1*0302 (P = 0.002) haplotypes, while lower anti-GAD titers were associated with the DRB1*070101 (P = 0.001) and DRB1*110101 (P < 0.001) alleles and DRB1*070101/DQB1*0201 (P = 0.001) and DRB1*110101/DQB1*030101 (P = 0.001) haplotypes. Mean anti-IA-2 antibody titers were higher in the DRB1*040101 allele (P = 0.007) and DRB1*040101/DQB1*0302 (P = 0.001) haplotypes but were lower in the DRB1*110101 allele (P = 0.010) and the DRB1*110101 (P < 0.001) and DRB1*110101/DQB1*030101 (P = 0.025) haplotypes. Multinomial regression analysis confirmed the positive association of DRB1*030101 and the negative association of DRB1*110101 and DQB1*030101, along with the DRB1*070101/DQB1*0201 and DRB1*110101/DQB1*030101 haplotypes, with anti-GAD levels. In contrast, only the DRB1*040101/DQB1*0302 haplotype was positively associated with altered anti-IA-2 titers. Increased GAD65 and IA-2 antibody positivity is differentially associated with select HLA class II alleles and haplotypes, confirming the heterogeneous nature of T1D.

Analysis of HLA-DRB1 polymorphisms in Japanese patients with primary biliary cirrhosis (PBC): The HLA-DRB1polymorphism determines the relative risk of antinuclear antibodies for disease progression in PBC

AIMS

Anti-gp210 and anti-centromere antibodies are different risk factors for the progression of primary biliary cirrhosis (PBC). However, the association of human leukocyte antigen (HLA) polymorphisms with these risk factors is unknown.

METHODS

We determined the HLA-DRB1 genotype in 334 Japanese PBC patients and studied their serum antibodies to gp210 and centromere during the 1-452-month observation period.

RESULTS

Anti-gp210 (odds ratio [OR] 46.56, 95% confidence interval [CI], 9.20-850.1) and anti-centromere antibodies (OR, 2.36, 95% CI, 1.28-4.35) were significant risk factors for jaundice- and nonjaundice-type progression, respectively. HLA-DRB1*0405 and *0803 predisposed patients to anti-gp210 (OR, 1.61, 95% CI, 1.08-2.39) and anti-centromere (OR, 2.30, 95% CI, 1.41-3.73) antibody production, respectively. HLA-DRB1*1502 and *0901 patients were predisposed to nonjaundice-type progression (OR, 1.98, 95% CI, 1.13-3.40 and OR, 1.78, 95% CI, 1.02-3.03), while HLA-DRB1*0803 and *0405 patients were predisposed to disease development (OR, 2.24, 95% CI, 1.48-3.41 and OR, 1.53, 95% CI, 1.11-2.11, respectively). Stratifying patients by HLA-DRB1 alleles revealed that anti-gp210 antibodies was a strong risk factor, regardless of the HLA-DRB1 alleles for jaundice-type progression, while anti-centromere antibodies was a significant risk factor for nonjaundice-type progression in patients with HLA-DRB1*0405 (OR, 6.89, 95% CI, 2.18-26.56) and -DRB1*0803 (OR, 5.42, 95% CI, 1.47-24.62) but not other HLA-DRB1 alleles.

CONCLUSIONS

HLA-DRB1 polymorphisms are significantly associated with not only disease development and progression but also antinuclear antibody production and the determination of the relative risk of antinuclear antibodies that contribute to PBC disease progression.

Immunogenetics of drug-induced skin blistering disorders. Part I: Perspective

The overall immunopathogenesis relevant to a large series of disorders caused by a drug or its associated hyperimmune condition is discussed based upon the examination of the genetics of severe drug-induced bullous skin problems (sporadic idiosyncratic adverse events, including Stevens-Johnson syndrome and toxic epidermal necrolysis). An overarching pharmacogenetic schema is proposed. Immune cognition and early-effector processes are focused upon and a challenging synthesis around systems evolution is explained by a variety of projective analogies. Etiology, human leukocyte antigen-B, immune stability, dysregulation, pharmacomimicry, viruses and an aggressive ethnically differentiated 'karmic' response are discussed.

Ocular myasthenia gravis and Graves disease in a 10-year-old child

We report the association between myasthenia gravis and Graves disease in a 10-year-old boy and discuss the important aspects of both diseases, the importance of recognizing the association, and the investigations of choice to distinguish the 2 disorders. Early diagnosis of the 2 disorders may help in effective treatment institution with more rapid treatment responses with a possible improvement in prognosis and clinical course. Resolution of myasthenia gravis is not expected until the euthyroid state is restored. We recommend complete thyroid status review on all patients presenting with ocular myasthenia gravis.

Islet autoantibodies are associated with HLA-DQ genotypes in Han Chinese patients with type 1 diabetes and their relatives

The objective of this study was to explore the relationship between islet autoantibodies of glutamic acid decarboxylase (GADA), islet antigen-2A (IA-2A), insulin autoantibody (IAA), and human leukocyte antigen (HLA)-DQ genotypes in type 1 diabetes (T1D) patients and their first-degree relatives (FDRs). Cross-sectional and case-control study. Four hundred and ninety-five T1D patients, 419 FDRs, and 376 control subjects in Han Chinese populations were recruited and tested for GADA and IA-2A, while 71 cases, all FDRs and 300 controls were tested for IAA. The 338 T1D patients (including 187 antibody-positive and 151 antibody-negative patients), 173 FDRs and 278 controls were genotyped for HLA-DQ with polymerase chain reaction sequencing-based method. Compared with the control, the frequency of DQA1*03-DQB1*0303, DQA1*05-DQB1*0201, and DQA1*03-DQB1*0401 haplotypes was higher (P < 0.05-0.01) but DQA1*0102-DQB1*0602 haplotype was lower (P < 0.01) in T1D patients. DQA1*03 allele was less in the FDRs than in their probands (P < 0.05). GADA was more prevalent in T1D patients carrying DQA1*05-DQB1*0201 or DQA1*03-DQB1*0401 haplotype (55.8% vs 41.0%, 65.5% vs 40.3%, P < 0.05-0.01), whereas IA-2A presented more in the patients carrying DQA1*03-DQB1*0303 haplotype (27.0% vs 7.9%, P < 0.05-0.01), both GADA and IA-2A showed frequently in the patients with DQA1*03-DQB1*0303/DQA1*05-DQB1*0201 haplotypes (34.5% vs 9.7%, P < 0.01). GADA positivity was lower in the patients with DQA1*0102-DQB1*0602 haplotype (16.7% vs 45.9%, P < 0.05). The frequency of IAA was not different between patients with and without susceptible DQ haplotypes (P > 0.05). GADA, IA-2A or IAA presented frequently in FDRs with DQA1*03-DQB1*0303 haplotype. The findings in the study indicate that some of specific HLA-DQA1/-DQB1 genotypes and haplotypes not only confer susceptibility to T1D but also are associated with the presence of the islet autoantibodies in the Han Chinese population.

Genomic profiling of interpopulation diversity guides prioritization of candidate-genes for autoimmunity

Autoimmune diseases seem to have strong genetic attributes, and are affected to some extent by shared susceptibility loci. The latter potentially amount to hundreds of candidate genes (CG), creating the need for a prioritization strategy in genetic association studies. To form such a strategy, 26 autoimmune-related CG were genotyped for a total of 72 single nucleotide polymorphisms (SNPs) in three distinct Israeli ethnic populations: Ashkenazi Jews, Sephardic Jews and Arabs. Four quantitative criteria reflecting population stratification were analyzed: allele frequencies, haplotype frequencies, the Fst statistic for homozygotes distribution and linkage disequilibrium extents. According to the consequent interpopulation genomic diversity profiles, the genes were classified into conserved, intermediate and diversified gene groups. Our results demonstrate a correlation between the biological role of autoimmune-related CG and their interpopulation diversity profiles as classified by the different analyses. Annotation analysis suggests that genes more readily influenced by environmental conditions, such as immunological mediators, are 'population specific'. Conversely, genes showing genetic conservation across all populations are characterized by apoptotic and cleaving functions. We suggest a research strategy by which CG association studies should focus first on likely conserved gene categories, to increase the likelihood of attaining significant results and promote the development of gene-based therapies.

Differences in the contribution of HLA-DR and -DQ haplotypes to susceptibility to adult- and childhood-onset type 1 diabetes in Japanese patients

To clarify heterogeneity in Japanese adult-onset type 1 diabetes, we analyzed the HLA-DR and -DQ haplotypes, depending on the clinical phenotype, and compared them with those in childhood-onset type 1 diabetes (CO). The patients in a previously reported Ehime Study were divided into subgroups by the mode of onset of diabetes: 68 acute-onset type 1 diabetic patients (AO) and 28 slowly progressive type 1 diabetic patients (SO). HLA haplotypes were compared with those of 80 CO patients and 190 control subjects. Two major susceptible HLA haplotypes in the Japanese, DRB1*0405-DQB1*0401 (DR4) and DRB1*0901-DQB1*0303 (DR9), were significantly increased in the AO and CO groups, but only DR9 was increased in the SO group. AO subjects had a higher frequency of DR9 than CO subjects. Accordingly, the DR9:DR4 frequency increased with increasing age of onset. Another susceptible haplotype, DRB1*0802-DQB1*0302 (DR8), was involved only in the CO group. Analysis of haplotype combinations revealed that DR4 and DR9 had significant dosage effects on the AO and CO groups (P < 0.0001), but only DR9 had such an effect in the SO group (P < 0.03). These results suggest differences in the contribution of HLA class II haplotypes to susceptibility of type 1 diabetes depending on the clinical phenotype and also indicate that HLA class II haplotypes may be associated with the onset age of type 1 diabetes.

HLA genotypes in turkish patients with myasthenia gravis: Comparison with multiple sclerosis patients on the basis of clinical subtypes and demographic features

The nature and intensity of the association of myasthenia gravis (MG) with distinct human leukocyte antigens (HLA) haplotypes differ between ethnic populations. The aims of the present study were to examine the relationship between HLA class I and II haplotypes and MG; to show the HLA associations with various MG subsets; and to investigate the association between MG and clinical subgroups of multiple sclerosis (MS) regarding HLA haplotypes. A total of 66 patients with MG were enrolled onto the study. The mean age at onset was 42.01 years. A total of 122 clinically definite MS patients and 188 healthy subjects were examined as control groups. The present study clearly showed associations with HLA-DR3, -B8, -A1, and -A2 in MG. In patients with early-onset MG, associations with HLA-DR3, -B8, and -A2 were stronger. When compared with MS, in the MG group, there was still a strong association with -B8, -DR3, and -A1. In subgroup analysis, there was no difference between MG and primary progressive MS patients. On the basis of the presence of anti-AChR antibodies, there was a statistically significant association with HLA-DR3. On the basis of presence of thymoma, no HLA allele showed clear associations in MG patients with thymoma. This is the first study to examine the relationship between HLA haplotypes and MG in the Turkish population and to compare MG with another autoimmune disease, MS, on the basis of the HLA haplotypes. Further investigations with a larger population are required to explain this finding.

Heterogeneous immunogenetic background in Japanese adults with myasthenia gravis

The aim of this study was to elucidate the roles of human leukocyte antigen (HLA) class II genes in disease susceptibility in Japanese adult patients with myasthenia gravis (MG). A number of studies have shown that MG is correlated with DR3 in Caucasians. In Japanese, infantile MG is associated with DR9, but the HLA class II alleles associated with adult MG remains unclear. HLA-DRB1 and DQB1 alleles were determined by genotyping in 75 Japanese adult patients with MG and in 115 race-matched healthy adults. No statistically significant difference was observed in the overall prevalences of DRB1 and DQB1 alleles between MG patients and healthy controls, even when the patients and controls were stratified on the basis of their gender. MG patients with DQB1*0604 were younger and those with DQB1*0402 were older at disease onset than those without (P=0.03 and 0.008, respectively). Concomitant autoimmune thyroid disease was associated with DRB1*0803 (P=0.0009, corrected P=0.04). In addition, anti-acetylcholine receptor antibody levels were significantly higher in patients with DQB1*0604 than in those without (P=0.045). These findings indicate that immunogenetic backgrounds in Japanese adult MG patients are heterogeneous and are apparently different from those in Caucasian patients.

Immunodominant epitopes on glycoprotein IIb-IIIa recognized by autoreactive T cells in patients with immune thrombocytopenic purpura

It was recently reported that autoreactive CD4(+) T cells to glycoprotein IIb-IIIa (GPIIb-IIIa) mediate antiplatelet autoantibody production in patients with immune thrombocytopenic purpura (ITP). To further examine the antigenic specificity of the GPIIb-IIIa-reactive T cells, 6 recombinant fragments encoding different portions of GPIIbalpha or GPIIIa were generated and tested for their ability to stimulate antigen-specific T-cell proliferation and anti-GPIIb-IIIa antibody production in vitro. T cells from the peripheral blood of 25 patients with ITP and 10 healthy donors proliferated in response to recombinant GPIIb-IIIa fragments in various combinations. The amino-terminal portions of both GPIIbalpha and GPIIIa (IIbalpha18-259 and IIIa22-262) were frequently recognized (60% and 64%, respectively) compared with other fragments (4%-28%) in patients with ITP, but this tendency was not detected in healthy donors. In subsequent analyses in patients with ITP, T-cell reactivities to IIbalpha18-259 and IIIa22-262 were consistently detected, whereas those to other fragments were sometimes lost. In vitro antigenic stimulation of peripheral blood mononuclear cells with IIbalpha18-259 or IIIa22-262 promoted the synthesis of anti-GPIIb-IIIa antibodies in patients with ITP, but not in healthy donors. Of 15 CD4(+) T-cell lines specific for platelet-derived GPIIb-IIIa generated from 5 patients with ITP, 13 lines recognized IIbalpha18-259, IIIa22-262, or both. T-cell lines reactive to IIbalpha18-259 or IIIa22-262 promoted the production of anti-GPIIb-IIIa antibodies that were capable of binding to normal platelet surfaces. These results indicate that the immunodominant epitopes recognized by pathogenic CD4(+) T cells in patients with ITP are located within the amino-terminal portions of both GPIIbalpha and GPIIIa.