HLA-DRB1*04 and HLA-DQB1*03 association with the atrophic but not with the goitrous form of chronic autoimmune thyroiditis in a Brazilian population

Vitamin D Receptor Gene Polymorphisms and Autoimmune Thyroiditis: Are They Associated with Disease Occurrence and Its Features?

Purpose

Vitamin D, besides its role in calcium-phosphorus metabolism, turned out to play a significant immunomodulating function. Until now four single nucleotide polymorphisms of vitamin D receptor gene (VDR), rs2228570 (FokI), rs1544410 (BsmI), rs7975232 (ApaI), and rs731236 (TaqI), have been studied in autoimmune thyroid disorders, with conflicting results. Another functional polymorphism of the VDR gene, rs11568820 (Cdx2), has been shown to influence the immune system, although it has not been studied for its association with autoimmune thyroiditis to date. Therefore, the study aimed to evaluate the association of these five VDR gene polymorphisms with susceptibility to autoimmune thyroiditis among Caucasian Polish population. A relationship between the studied polymorphisms and selected clinical features of the disease was additionally assessed.

Methods

223 patients with autoimmune thyroiditis and 130 control subjects were enrolled in the study. VDR polymorphisms were studied by PCR-RFLP or TaqMan real-time PCR.

Results

Allele and genotype distributions of any of the studied polymorphisms did not differ significantly between patients and controls. Similarly, frequencies of haplotypes derived from rs1544410-rs7975232-rs731236 (BsmI-ApaI-TaqI) polymorphisms were not significantly different in the two studied groups. However, a weak association between rs1544410 (BsmI) or rs7975232 (ApaI) VDR polymorphisms and thyroid volume was found (p = 0.03 and p = 0.04, resp.).

Conclusions

Our results suggest that VDR gene is not a major susceptibility factor for autoimmune thyroiditis development, at least in Caucasian Polish population.

An exploratory phenome wide association study linking asthma and liver disease genetic variants to electronic health records from the Estonian Biobank

The Estonian Biobank, governed by the Institute of Genomics at the University of Tartu (Biobank), has stored genetic material/DNA and continuously collected data since 2002 on a total of 52,274 individuals representing ~5% of the Estonian adult population and is increasing. To explore the utility of data available in the Biobank, we conducted a phenome-wide association study (PheWAS) in two areas of interest to healthcare researchers; asthma and liver disease. We used 11 asthma and 13 liver disease-associated single nucleotide polymorphisms (SNPs), identified from published genome-wide association studies, to test our ability to detect established associations. We confirmed 2 asthma and 5 liver disease associated variants at nominal significance and directionally consistent with published results. We found 2 associations that were opposite to what was published before (rs4374383:AA increases risk of NASH/NAFLD, rs11597086 increases ALT level). Three SNP-diagnosis pairs passed the phenome-wide significance threshold: rs9273349 and E06 (thyroiditis, p = 5.50x10^-8); rs9273349 and E10 (type-1 diabetes, p = 2.60x10^-7); and rs2281135 and K76 (non-alcoholic liver diseases, including NAFLD, p = 4.10x10^-7). We have validated our approach and confirmed the quality of the data for these conditions. Importantly, we demonstrate that the extensive amount of genetic and medical information from the Estonian Biobank can be successfully utilized for scientific research.

Vitamin D in Hashimoto's thyroiditis and its relationship with thyroid function and inflammatory status

Several studies have shown the correlation between vitamin D [25(OH)D] deficiency and thyroid autoimmunity and reducing of thyroid autoantibodies in patients with normal levels of vitamin D combining with thyroid hormone replacement. However, other authors not agree with this association. It is still unclear whether the low 25(OH)D levels are the result of HT disease or a part of its cause. We studied 88 patients with HT regarding vitamin D status and thyroid autoimmunity markers as well as the relationship with cytokines produced by Th1, Th2, and Th17 cells compared with a control group of 71 euthyroid healthy subjects. The present study demonstrated that vitamin D concentrations were similar in patients HT and the control group. The reduction of free T4 levels was a predictor of vitamin D insufficiency for Hashimoto's thyroiditis, but not for the control group. Lower concentrations of TNF-α was a predictor of lower levels of vitamin D. Differences in the association between HT and vitamin D insufficiency remain unresolved in the literature. The thyroid hormone status would play a role in the maintenance of vitamin D sufficiency, and its immunomodulatory role would influence the presence of autoimmune thyroid disease. The positive correlation between free T4 and vitamin D concentrations suggests that adequate levothyroxine replacement in HT would be an essential factor in maintaining vitamin D at sufficient levels.

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.

Major histocompatibility complex class II (DRB1*, DQA1*, and DQB1*) and DRB1*04 subtypes' associations of Hashimoto's thyroiditis in a Greek population

Hashimoto's thyroiditis (HT) is an autoimmune disease resulting from complex interactions between genetic and environmental factors. The disease is associated with certain human leukocyte antigen (HLA) class II alleles in various populations. We aimed to determine in this study, for the first time in a Greek population, the association of HLA-DRB1*, -DQA1*, and -DQB1* alleles with HT. HLA-DRB1*, -DQA1*, and -DQB1* alleles' and -DRB1*04 subtypes' distribution was evaluated in 125 patients with HT and in 500 healthy control individuals by using a DNA-based sequence-specific primer method. Chi(_)squared tests and Bonferroni correction method were applied in the statistical analysis of the data. Significantly higher frequency of DRB1*04 (24.8% vs 7.7%, P < 0.0001) was observed in HT patients, while HLA-DRB1*07 was significantly decreased (2.8% vs 7.9%, P < 0.05). HLA-DRB1*04 subtyping showed a significant increase of DRB1*0405 (21% vs 7.8%, P < 0.0001) in HT patients. Also significant high frequencies of DQB1*0201 (14.8% vs 8.2%, P < 0.001), DQB1*0302 (18.8% vs 7.0%, P < 0.0001), and DQA1*0301 (25.6% vs 7.8%, P < 0.0001) were recorded in the patient group. Conducting the first research of this kind in a Greek population, our study tries to provide an evaluation of the prevalence of HT relating to HLA-DRB1*0405, and we report a relative risk of 2.7 for HT in a Greek population.

Alternate splicing of interleukin-1 receptor type II (IL1R2) in vitro correlates with clinical glucocorticoid responsiveness in patients with AIED

Autoimmune Inner Ear Disease (AIED) is poorly characterized clinically, with no definitive laboratory test. All patients suspected of having AIED are given glucocorticoids during periods of acute hearing loss, however, only half initially respond, and still fewer respond over time.

We hypothesized that AIED is a systemic autoimmune disease characterized by dysfunctional peripheral blood mononuclear cells (PBMC) responses to a unique cochlear antigen(s). To test this hypothesis, we examined end-stage AIED patients undergoing cochlear implant surgery and compared autologous perilymph stimulated PBMC from AIED patients to controls. We determined that autologous perilymph from AIED patients was unable to induce expression of a long membrane-bound Interleukin-1 Receptor Type II (mIL1R2) transcript in PBMC as compared with controls, despite similar expression of the short soluble IL1R2 (sIL1R2) transcript (p<0.05). IL1R2 is a molecular decoy that traps interleukin-1β (IL-1β) and does not initiate subsequent signaling events, thereby suppressing an inflammatory response. IL1R2 transcript length is regulated by alternate splicing, and the major inhibitory function is attributed to the full-length mIL1R2. In addition, IL1R2 expression is induced by dexamethasone.

Separately, we prospectively examined patients with newer onset glucocorticoid-responsive AIED. Immediately prior to clinical treatment for acute deterioration of hearing thresholds, their PBMC demonstrated a robust induction of mIL1R2 in PBMC in response to dexamethasone in vitro that correlated with a clinical response to prednisone in vivo (p<0.0001) as measured by hearing restoration. In contrast, clinically steroid unresponsive patients demonstrated high basal levels of mIL1R2 in their PBMC and only minimally augmented expression in response to dexamethasone. Thus, induced expression of mIL1R2 appears to be a protective mechanism in hearing homeostasis and warrants further investigation in a large prospective clinical trial to determine if IL1R2 can be used as a specific biomarker for AIED.

Environmental factors and genetic background that interact to cause autoimmune thyroid disease

PURPOSE OF REVIEW

To provide an updated list of genetic and environmental causative factors of autoimmune thyroid disease, and report about the recent discoveries concerning their interaction in the pathogenesis of thyroid autoimmunity.

RECENT FINDINGS

Although significant discoveries have been made on genetic and environmental factors underlying the development of autoimmune thyroid disease, few data are available about the mechanisms by which they interact. The most interesting news in this field comes from research on molecular mimicry between microbial antigens and thyroid autoantigens. The molecular mimicry model postulates that, in predisposed subjects, a microbial antigen could trigger autoimmunity because of its structural similarity to an autoantigen of the host, and is a paradigmatic example of the multifactorial interaction of several genes and environmental factors to cause autoimmune diseases, including thyroid diseases.

SUMMARY

Recent findings help us to better understand the functional mechanisms of the immune system, which are still only partially known. Beyond the scientific interest, this knowledge has immediate repercussions on clinical practice because it can suggest possible therapeutic targets for new treatments, as well as better and more specific uses of currently available drugs and resources.

Association of HLA DQ B1* and HLA DR B1* Alleles with Goitrous Juvenile Autoimmune Hypothyroidism—A Case Control Study

The present study was designed to analyze the distribution of HLA DQ B1* and DR B1* in patients with goitrous juvenile autoimmune hypothyroidism from Hyderabad, India. Analysis indicated an increase in the frequencies of HLA DQ B1* 03 allele (P < 0.000) and HLA DR B1* 04 (P < 0.05) alleles in this group of patients when compared to the controls, whereas the frequency of DQB1* 05 was found to be decreased in patients' group compared to the controls (p < 0.01). To conclude, we report a positive correlation between DQ B1* 03 and DR B1* 04 and goitrous juvenile autoimmune hypothyroidism, whereas DQB1* 05 is observed to be negatively correlated with this thyroid dysfunction. Since the disease-susceptible HLA class II alleles appear to differ in various ethnic groups for some autoimmune diseases, the observed association from Indian series of patients holds significance.

Low prevalence of hypothyroidism among black and Mulatto people in a population-based study of Brazilian women

Objective African-Americans have been shown to have low prevalence of hypothyroidism. Brazil has a high ethnic admixture allowing further exploration into whether environmental factors can explain the ethnic differences. Design A survey, representative of the population of Rio de Janeiro, a large metropolitan city in Brazil. Factors studied included race, parity, income, schooling, and smoking. Population The survey was carried out in Rio de Janeiro whereby households (1500) were selected using three-stage probability sampling. A total of 1298 (86.5%) women participated in the survey (non-response: 13.5%). Measurements TSH from blood drawn at the households. Anti-thyroperoxidase (anti-TPO) antibodies and free T4 were also measured. Results Overall prevalence of hypothyroidism (TSH > 4 mUI/ml or taking medication) was 12.3%. Prevalence was 6.9% in black people, 8.8% in Mulatto people, and 16.7% among white people. The mean serum TSH of the population was 2.65 (95% confidence interval 2.33-2.97). The TSH distribution of black and Mulatto people was shifted to the left compared to white people. After adjustment for age, income, smoking and presence of anti-TPO, Black and Mulatto people were still protected from hypothyroidism. The adjusted odds ratio for black compared to white people was 0.45 (95% CI 0.30-0.68) and for Mulatto people was 0.34 (95% CI 0.18-0.63). Serum TSH levels were significantly lower in smokers than in non-smokers, but there was no association between number of cigarettes smoked and serum TSH level. Conclusions This is the first time it has been demonstrated that Mulatto people have a prevalence of hypothyroidism which lies between that of white and black people, independent of the prevalence of anti-TPO and smoking.