Human lymphocyte antigens (HLA) and Graves' disease in Turkey

Critical amino acid variations in HLA-DQB1* molecules confers susceptibility to Autoimmune Thyroid Disease in south India

The HLA-DQB1* region exhibits complex associations with autoimmune thyroid disease (AITD). AITD patients (Hashimoto's thyroiditis, HT = 180; Graves' disease, GD = 55) and age/sex matched controls (n = 235) were genotyped for DQB1* alleles by PCR-SSP. Alleles DQB1*02:02, *06:03, *06:09, *03:02, and *03:03 showed an increased risk and *02:01, *05:02, and *06:02 showed a protection toward AITD. Multiple sequence alignment was used to find out the amino acid variations within the peptide-binding pockets of susceptible and/or protective DQB1* alleles. We observed susceptible associations for amino acids 'Glu⁸⁶(P < 0.0007)' and 'Leu⁸⁷(P < 3.8 × 10^-4)' in P1, 'Leu²⁶(P < 4.0 × 10^-12)' in P4, 'His⁹(P < 5.0 × 10^-4)' and 'Ala⁵⁷(P < 3.6 × 10^-4)' in P9 toward HT; and 'Gly⁸⁶(P < 0.0004)' in P1 and 'Asp⁵⁷(P < 1.9 × 10^-4)' in P9 towards GD. Protective associations were observed for amino acids 'Ala⁸⁶(P < 8.2 × 10^-6)' and 'Tyr⁸⁷(P < 0.0003)' in P1, 'Gly²⁶(P < 4.9 × 10^-5)' and 'Ser⁷⁴(P < 4.9 × 10^-5)' in P4, 'Phe⁹(P < 0.0007)' and 'Ser⁵⁷(P < 0.0016)' in P9 towards HT. Thus, the present study revealed that DQB1* alleles and putative amino acid residues play an important role in susceptibility toward AITD in south India.

Autoimmune thyroid disease elicited by NY-ESO-1 vaccination

BACKGROUND

Immunotherapies and targeted therapies are frequently associated with thyroid dysfunction, which is in contrast with the rare thyroid abnormalities induced by cytotoxic agents. Immunotherapy with NY-ESO-1, a tumor-associated antigen expressed by a number of malignancies, was reported to trigger hyperthyroidism or hypothyroidism in two HLA-A2 patients with ovarian cancer. We describe now a case of Graves' disease triggered by NY-ESO-1 in a HLA-A2-negative woman.

PATIENT FINDINGS

A 32-year-old woman with a synovial sarcoma received radiotherapy, chemotherapy, and finally NY-ESO-1 vaccine. The patient was found to have HLA A11/A33(19), B13/B56(22), Cw3/-. One month after the beginning of immunotherapy, thyroid dysfunction was clinically suspected and Graves' disease was biochemically confirmed. Fearful of the antithyroid drugs' side effects, the patient was treated with a beta-blocker (propranolol, 80-20 mg/day). As hyperthyroidism progressively worsened, the patient underwent total thyroidectomy. We hypothesized that NY-ESO-1 shared partial homology with thyroid autoantigens (the so-called molecular mimicry mechanism) and that at least one pair of homologous sequences contained amino acid sequence binding motifs to a restricted number of HLA molecules. We used BLAST software to search amino acid sequence homologies between NY-ESO-1 and thyroid autoantigens (thyrotropin receptor [TSH-R], thyroperoxidase, and thyroglobulin), and the HLA ligand/motif database to look for HLA/T-cell receptor binding motifs in the regions of NY-ESO-1 and thyroid autoantigens that were homologous. We found 15 epitopic regions of NY-ESO-1 homologous to 15 regions of thyroid autoantigens, some of which epitopic: 5 of TSH-R, 8 of thyroglobulin, and 2 of thyroperoxidase. These homologous sequences contain binding motifs belonging to several HLA class I antigens, including HLA A2 and the patient's A11 and A33.

SUMMARY

Genetically predisposed patients who receive NY-ESO-1 vaccination are at risk to develop thyroid dysfunction.

CONCLUSIONS

Considering the increasing use of NY-ESO-1, thyroid dysfunctions induced by NY-ESO-1 are expected to increase in cancer patients over the next years.

Human thyroid autoantigens and proteins of Yersinia and Borrelia share amino acid sequence homology that includes binding motifs to HLA-DR molecules and T-cell receptor

We previously reported that the spirochete Borrelia burgdorferi could trigger autoimmune thyroid diseases (AITD). Subsequently, we showed local amino acid sequence homology between all human thyroid autoantigens (human thyrotropin receptor [hTSH-R], human thyroglobulin [hTg], human thyroperoxidase [hTPO], human sodium iodide symporter [hNIS]) and Borrelia proteins (n = 6,606), and between hTSH-R and Yersinia enterocolitica (n = 1,153). We have now updated our search of homology with Borrelia (n = 11,198 proteins) and extended our search on Yersinia to the entire species (n = 40,964 proteins). We also searched the homologous human and microbial sequences for peptide-binding motifs of HLA-DR molecules, because a number of these class II major histocompatibility complex (MHC) molecules (DR3, DR4, DR5, DR8, and DR9) are associated with AITD. Significant homologies were found for only 16 Borrelia proteins (5 with hTSH-R, 2 with hTg, 3 with hTPO, and 6 with hNIS) and only 19 Yersinia proteins (4 with hTSH-R, 2 with hTg, 2 with hTPO, and 11 with hNIS). Noteworthy, segments of thyroid autoantigens homologous to these microbial proteins are known to be autoantigenic. Also, the hTSH-R homologous region of one Borrelia protein (OspA) contains an immunodominant epitope that others have found to be homologous to hLFA-1. This is of interest, as the hLFA-1/ICAM-1 ligand/receptor pair is aberrantly expressed in the follicular cells of thyroids affected by Hashimoto's thyroiditis. A computer-assisted search detected antigenic peptide binding motifs to the DR molecules implicated in AITD. In conclusion, our in silico data do not directly demonstrate that Borrelia and Yersinia proteins trigger AITD but suggest that a restricted number of them might have the potential to, at least in persons with certain HLA-DR alleles.

Type 1 autoimmune hepatitis in Turkish patients: absence of association with HLA B8

BACKGROUND

There is very little information about autoimmune hepatitis (AIH) in populations other than of white European or Japanese descent.

GOALS

To investigate the presenting features, immunogenetic background, and response to standard immunosuppressive therapy in native Turkish patients with AIH.

METHODS

Retrospective analysis of all patients referred between 1994 and 2000 to our hepatology clinic in Ankara who fulfilled international criteria for definite or probable type 1 or type 2 AIH.

RESULTS

Seventeen patients (15 female; median age, 31 years; range, 13-56 years) were identified. All had type 1 AIH. Clinical and laboratory features were broadly similar to those reported for white or Japanese patients. Five had the HLA DR3 allotype and 10 had DR4; however, in contrast to white and Japanese patients, DR4 was not associated with an older age at onset. Importantly, no patient had the B8 allotype (vs. 10.9% in 110 healthy Turkish subjects). Thus, none had the classic A1-B8-DR3 autoimmune haplotype: a major distinction from white individuals.

CONCLUSIONS

There appears to be genetic differences in type 1 AIH between Turkish and other populations. Genotyping of Turkish patients to identify alleles that may confer susceptibility or resistance to AIH may progress understanding of the genetic basis of the disease.

Relationship between HLA antigens and infectious agents in contributing towards the development of Graves' disease

Graves' disease (GD) is an autoimmune thyroid disorder which is associated with the human leucocyte antigens HLA-DR3 and DQA1* O501 in Caucasians. We have explored the possibility that some patients with certain HLA specificities develop anti-HLA antibodies which are correlated with environmental factors that may contribute to the development of GD. We studied 40 GD patients and 157 healthy individuals (controls). Serology was used to type HLA-A, -B, -Cw, and -DR antigens. The frequencies of these antigens in relation to lymphocytotoxic anti-HLA-A-B-Cw-DR antibodies and two environmental factors (Yersinia enterocolitica and Coxsackie B virus) were determined. The frequencies of HLA-B15, -B21 and DR3 antigens were increased, whereas HLA-DR5 antigen was decreased in GD patients. A significant association between HLA-DR3 antigen and lymphocytotoxic antibodies was observed, i.e., IgGs from GD patients were cytotoxic to HLA-DR3+ normal B cells. Following absorption with Yersinia enterocolitica or Coxsackie-B-virus, only Coxsackie-B virus completely inhibited the lymphocytotoxic reactions against HLA-DR3+ B cells. Besides confirming the association of HLA-DR3 with GD, this study also suggests the role of Coxsackie-reactive HLA-DR3 antibodies as contributing factors to the pathogenesis of the disease.

HLA-DQ3 is associated with Graves' disease in African-Americans

HLA heterogeneity occurs in various ethnic groups and has been significantly associated with Graves' disease. In this study we have determined that DQ3 is associated with Graves' disease in African-Americans. Human leukocyte antigen (HLA) typing of D-region antigens in 139 controls and 45 Graves' disease patients reveals significant differences for HLA-DR2, DR9, DQ1, and DQ3. The latter remained significant after correction. Increases in HLA-DR9 and DR3 are associated with increases in DQ3 and DQ2, respectively. The decrease in DR2 is associated with a decrease in DQ1. The associated increases and decreases in DR with DQ antigens probably reflect linkage disequilibrium. Patients were evaluated for autoantibodies against microsomal antigens and/or against thyroglobulin. All of the normal control volunteers were negative for thyroid antibodies and thirteen percent of patients produced autoantibodies. No significant associations were detected for antibody production, type of treatment required, age of onset, family history of Graves', status of T3, T4 levels, goiter and/or ophthalmopathy.