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Summary Vitamin D (VD) has been implicated in type 1 diabetes (T1D) by genetic and epidemiological studies. Individuals living in regions with low sunlight exposure have an increased T1D risk and VD supplementation reduced the risk in human individuals and mouse models. One possibility of how VD influences the pathogenesis of T1D is its immunomodulatory effect on dendritic cells (DC), which then preferentially activate regulatory T cells (Tregs). In the present pilot study, we collected blood samples from a small cohort of patients with T1D at baseline and months 6 and 12. VD-deficient patients were advised to supplement with 1000 IU/day VD. We found a considerable variation in the VD plasma level at baseline and follow-up. However, with higher VD plasma levels, a lower frequency of interleukin (IL)-4-producing CD8 T cells was observed. We further performed a comprehensive genotyping of 13 VD-related polymorphisms and found an association between VD plasma level and the genotype of the VD binding protein (DBP). The frequency of DC and T cell subsets was variable in patients of all subgroups and in individual patients over time. Nevertheless, we found some significant associations, including the 1,25-dihydroxyvitamin D3 hydroxylase (CYP27B1) genotype with the frequency of DC subtypes. In summary, our preliminary results indicate only a limited influence of the VD plasma level on the immune balance in patients with T1D. Nevertheless, our pilot study provides a basis for a follow-up study with a larger cohort of patients.

Common polymorphisms of the vitamin D receptor gene have been reported to affect the risk of breast, colon, prostate, and differentiated thyroid cancer (DTC), but polymorphisms within the genes of vitamin D metabolizing enzymes have not been studied in DTC. The aim of the present study was to investigate the genes for vitamin D enzymes in patients with DTC and healthy controls (HC) as well as the vitamin D (25-hydroxyvitamin D(3), and 1,25-hydroxyvitamin) status.German patients (n=253) with DTC (papillary thyroid carcinoma [PTC] and follicular thyroid carcinoma [FTC]) and HC (n=302) were genotyped for polymorphisms within the vitamin D metabolizing enzymes such as 25-hydroxylase (CYP2R1[rs12794714, rs10741657]), 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1[rs10877012, rs4646536]), and 25-hydroxyvitamin D 24-hydrolase (CYP24A1[rs927650, rs2248137, rs2296241]). Furthermore, the 25-hydroxyvitamin D(3) [25(OH)D(3)] and 1,25-hydroxyvitamin [1,25(OH)(2)D(3)] plasma levels were measured by a radioimmunoassay.There was no difference in the genotypes; however, the CYP24A1 haplotype analysis showed that rs2248137C/rs2296241A (13.1% vs. 19.1%; corrected p [pc]=0.04) was less frequent in the PTC, whereas the haplotypes rs2248137C/rs2296241G (56.0% vs. 41.9%; pc=0.03), rs927650C/rs2296241G (22.5% vs. 8.4%; pc=1.6×10(-3)), and rs927650C/rs2248137C/rs2296241G (21.1% vs. 7.3%; pc=1.5×10(-3)) were more frequent in the FTC compared with HC. Furthermore, if patients and controls were grouped according to four 25(OH)D(3) categories (severely deficient, deficient, insufficient, and sufficient), then the patients with both DTC subtypes had significantly lower levels of circulating 1,25(OH)(2)D(3), especially in the group with a deficient 25(OH)D(3) status compared with the controls. Although the polymorphisms showed no differences stratified for the four 25(OH)D(3) categories, the activation status by 1,25(OH)(2)D(3) differed significantly depending on the genotypes of the investigated CYP24A1 polymorphisms.A higher risk for DTC is conferred by haplotypes within the CYP24A1 gene, low circulating 25(OH)D(3) levels (deficiency), and a reduced conversion to 1,25(OH)(2)D(3). These results confirm and extend previous observations and also support a role of the vitamin D system in the pathogenesis of DTC. How deficient 25(OH)D(3) levels in combination with certain CYP24A1 haplotypes affect vitamin D activation is the subject of future studies.

Vitamin D is a secosteroid hormone that resembles other nuclear steroid hormones such as thyroid, gluco-, and mineralocorticoids, as well as gonadal effector systems. Primarily understood as a master regulator of bone and calcium/phosphate physiology, it is now increasingly recognized as orchestrating numerous aspects of cell growth and differentiation in many tissues, including those of innate and acquired immunity. This review addresses recently discovered aspects that highlight vitamin D's potential for immune intervention and how the vitamin D pathway is utilized for anti-infective and antineoplastic immunity. This provides the rationale for novel therapeutic strategies in the context both of prevention and of therapy of immune dysregulation in type 1 diabetes.

BACKGROUND Autoimmune thyroiditis occurs in 10–25% of patients with type 1 diabetes (T1D). Most of these patients are also positive for thyroid peroxidase (TPO) antibodies. Thyroid dysfunction complicates T1D metabolic control and is a component of the autoimmune polyglandular syndrome (APS, type 2 or 3). Previous studies of isolated T1D and of T1D combined with other autoimmune disorders showed genetic susceptibility for alleles in HLA-DQB1 and -DRB1 and also CTLA4 and PTPN22. RESEARCH DESIGN AND METHODS We analyzed the Type 1 Diabetes Genetics Consortium Autoantibody Workshop data by differentiating those T1D probands with and without TPO antibodies or thyroid disease with respect to polymorphisms in HLA, CTLA4, INS, PTPN22, and VDR, taking into account the ethnic origin. Genotype and clinical/immunogenic phenotype data were analyzed by gene counting methods and logistic regression analysis. RESULTS The presence of TPO antibodies (25.2%) and thyroid disease (8.4%) was associated with older age, female sex, and presence of other autoantibodies (GAD65, ATPase, 21-OH) (all P < 0.001). The highest prevalence was in patients of Hispanic ancestry (31%) and the lowest in those of African ancestry (8%). In T1D non-Hispanic whites, HLA-DRB1*0101 is significantly (P < 0.0001) less frequent in TPO-positive than in TPO-negative individuals, whereas HLA-DRB1*0404, -DQB1*0301, and -DPB1*0201 are significantly (P < 0.0001) more frequent. Subjects with a high titer of TPO autoantibodies and with thyroid disease were associated with female sex and older age and negatively associated with DRB1*0401-DQB1*0302 (P < 0.0001). No significant differences were observed for an association of TPO positivity or thyroid disease with single nucleotide polymorphisms in the INS, CTLA4, or VDR loci, with nominal significance (P = 0.01) for PTPN22 R620W variant. CONCLUSIONS Thyroid autoimmunity is highly prevalent in T1D patients of non-Hispanic white, Asian, or Hispanic origin. The strongest disease risk is conferred by female sex and older age. This risk is modulated by HLA-DRB1 and HLA-DPB1 loci. The immunogenetic profile for T1D with thyroid autoimmunity may identify distinct pathways regulating polyglandular autoimmunity and disease.

Background Three genes have been confirmed as major joint susceptibility genes for endocrine autoimmune disease:human leukocyte antigen class II, cytotoxic T-lymphocyte antigen 4 and protein tyrosine phosphatase non-receptor type 22. Recent studies showed that a genetic variation within the interferon induced helicase domain 1 (IFIH1) locus (rs1990760 polymorphism) is an additional risk factor in type 1 diabetes and Graves' disease (GD). Methods The aim of the present study was to investigate the role of the rs1990760 polymorphism within the IFIH1 gene in German patients with GD (n = 258), Hashimoto's thyroiditis (HT, n = 106), Addison's disease (AD, n = 195) and healthy controls (HC, n = 227) as well as in 55 GD families (165 individuals, German) and 100 HT families (300 individuals, Italian). Furthermore, the interaction between rs1990760 polymorphism with human leukocyte antigen (HLA) risk haplotype DQ2(DQA*0501-DQB*0201), the risk haplotypes DQ2/DQ8 (DQA*0301-DQB*0302) and the status of thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb) and TSH receptor antibody (TRAb) in patients and families were analysed. Results No significant differences were found between the allele and genotype frequencies for rs1990760 IFIH1 polymorphism in patients with GD, HT, AD and HC. Also no differences were observed when stratifying the IFIH1 rs1990760 polymorphism for gender, presence or absence of thyroid antibodies (GD:TRAb and HT:TPOAb/TgAb) and HLA risk haplotypes (DQ2:for GD and HT, DQ2/DQ8:for AD). Furthermore the transmission analysis in GD and HT families revealed no differences in alleles transmission for rs1990760 IFIH1 from parents with or without HLA risk haplotype DQ2 to the affected offspring. In contrast, by dividing the HT parents according to the presence or absence of thyroid Ab titers, mothers and fathers both positive for TPOAb/TgAb overtransmitted the allele A of IFIH1 rs1990760 to their HT affected offspring (61.8% vs 38.2%;p = 0.05;corrected p [pc] = 0.1). However, these associations did not remain statistically significant after correction of the p-values. Conclusion In conclusion, our data suggest, no contribution from IFIH1 rs1990760 polymorphism to the pathogenesis of either Graves' disease, Hashimoto's thyroiditis or Addison's disease in our study populations. However, in order to exclude a possible influence of the studied polymorphism in specified subgroups within patients with autoimmune thyroid disease, further investigations in larger populations are needed.