Vitamin D receptor initiation codon polymorphism in Japanese patients with Graves' disease

Vitamin D pathway gene polymorphisms, vitamin D level, and cytokines in children with type 1 diabetes

AIMS

The study aimed to examine genetic polymorphism of vitamin D-related genes and association between those genes and vitamin D and cytokines levels in children with type 1 diabetes (T1D).

MATERIALS AND METHODS

This study was conducted among 100 T1D children and 100 controls at Division of Endocrinology and Metabolism, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, during 2016 to 2018. Vitamin D metabolite levels were measured by liquid chromatography-tandem mass spectrometry method, serum cytokine levels of IFN- ɣ, IL-10, IL-13, IL-17α, IL-2, IL-4, IL-6, and TNF-α by immunoassay, and genetic variations at VDR, CYP2R1, CYP27B1, GC, DHCR7, and CYP24A1 by polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

A relationship between studied single nucleotide polymorphisms and T1D was found in CYP2R1 (rs10741657) (GA, OR: 1.83, 95% CI: 1.01-3.31; p = 0.04). VDR haplotypes were also remarkably different between T1D patients and controls. Controls had higher frequency of haplotype TACT than T1D patients (p = 0.02). Vitamin D and all cytokine levels, except for IL-17α, were significantly increased in T1D compared to controls. The polymorphism of DHCR7 (rs12785878) was positively associated with 25OHD₃ and 3epi25OHD₃ levels and was negatively associated with 25OHD₂ level. On the other hand, polymorphism of CYP27B1 (rs4646536) was negatively associated with 3epi25OHD₃ level. Polymorphisms of CYP27B1 (rs4646536) and GC (rs2282679) were positively associated with TNF-α levels. VDR variation of rs1544410, rs731236, and rs7975232 also showed negative association with IL-10 levels. In contrast, the level of IL-10 was positively associated with DHCR7 (rs12785878).

CONCLUSION

Relationships between T1D and CYP2R1 polymorphism and VDR haplotype were found. Vitamin D gene-related variations were associated with vitamin D and circulating cytokine levels in children with T1D.

Association between vitamin D receptor gene polymorphisms and Graves' disease: a systematic review and meta-analysis

PURPOSE

The pathogenesis of Graves' disease (GD) and orbitopathy (GO) is not completely elucidated. On the other hand, vitamin D receptor (VDR) gene polymorphisms have been associated with vulnerability to a plethora of chronic autoimmune diseases. The primary aim of this study was to synthesize evidence on the association between VDR gene polymorphisms and GD. Secondary aim was to investigate their association with GO.

METHODS

A comprehensive search was conducted in PubMed, CENTRAL and Scopus, up to December 8, 2018. Data were expressed as odds ratio (OR) with 95% confidence intervals (CI). Heterogeneity was quantified with I² index.

RESULTS

Ten studies were included in the qualitative and quantitative analysis. TT subtype of TaqI polymorphism was associated with an increased risk of GD compared with Tt and tt polymorphisms (OR: 1.42; 95% CI, 1.05-1.94, p = 0.025), whereas tt was associated with a lower risk of GD, compared with TT and Tt polymorphisms (OR: 0.79; 95% CI, 0.62-0.99, p = 0.043). No association was found for ApaI, BsmI, and FokI polymorphisms. The bb subtype of BsmI polymorphism was associated with a lower risk in Asian, but with a higher GD risk in Caucasian populations, compared with BB/Bb subtypes. No eligible study was found regarding the association between VDR gene polymorphisms and the risk of GO.

CONCLUSIONS

The TT subtype of the TaqI polymorphism was associated with a higher susceptibility for GD compared with Tt and tt. Regarding BsmI, the bb subtype was associated with increased GD risk in Caucasians, whereas it is protective in Asians.

25 Hydroxyvitamin D Deficiency and Its Relationship to Autoimmune Thyroid Disease in the Elderly

Background: Low 25(OH) vitamin D levels have been associated with several autoimmune diseases and recently with autoimmune thyroiditis (AT). The aim of the study was to investigate the association of AT with low 25(OH) vitamin D levels in the elderly. Methods: One hundred sixty-eight elderly subjects (mean age: 81.6 ± 9.4 years) were enrolled. Serum levels of 25(OH) vitamin D, anti-thyroid peroxidase (TPO-Ab), anti-thyroglobulin (TG-Ab) antibodies, free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) were measured. Results: The prevalence of AT was significantly higher in subjects with vitamin D deficiency (25(OH) vitamin D < 20 ng/mL) when compared with subjects with normal 25(OH) vitamin D (25(OH) vitamin D ≥ 20 ng/mL) levels (28% vs. 8%, respectively, p = 0.002). Patients with AT and vitamin D deficiency had a comparable hormonal profile compared to patients with AT and vitamin D sufficiency in terms of TSH (p = 0.39), FT3 (p = 0.30), FT4 (p = 0.31), TG-Ab (0.44) and TPO-Ab (0.35). Interestingly, a significant correlation between 25(OH) vitamin D and TPO-Ab (r = −0.27, p = 0.03) and FT3 (r = 0.35, p = 0.006) has been found in subjects with AT while no correlation was found between 25(OH) vitamin D levels and TG-Ab (r = −0.15, p = 0.25), TSH (r = −0.014, p = 0.09) and FT4 (r = 0.13, p = 0.32). Conclusions: These findings suggest that vitamin D deficiency was significantly associated with AT in the elderly. Therefore, the screening for AT should be suggested in subjects with vitamin D deficiency.

Vitamin D receptor gene polymorphisms and type 1 diabetes mellitus in a Korean population

BACKGROUND

Vitamin D receptor (VDR) has been suggested to play a role in the pathogenesis of type 1 diabetes mellitus (T1DM). There has been no case-control study examining the association between VDR polymorphisms and T1DM among Korean subjects with a low incidence of T1DM.

METHODS

Eighty-one T1DM patients and 113 unrelated healthy controls with no history of DM or other autoimmune diseases were investigated at either Pusan National University Children's Hospital or Korea University Anam Hospital between March 2009 and September 2013. Polymerase chain reaction-restriction fragment length polymorphism was utilized to genotype single nucleotide substitutions at TaqI, BsmI, and ApaI alleles.

RESULTS

All frequencies in T1DM and control subjects were in Hardy-Weinberg equilibrium, although ApaI in controls and TaqI in T1DM showed relatively weak equilibrium. TaqI and BsmI differences were significant (P = 0.045 and P = 0.012, respectively) after applying Bonferroni correction. The TT genotype carrier frequency among controls was higher than among the T1DM patients (P = 0.015; OR, 2.98; 95%CI: 1.19-7.42). T allele frequency was higher among controls than T1DM patients (P = 0.019; OR, 2.78; 95%CI: 1.15-6.72). The frequency of bb genotype carriers among controls was higher than among T1DM patients (P = 0.004; OR, 4.13; 95%CI: 1.4-12.10). The frequency of the b allele among controls was higher than that among T1DM patients (P = 0.016; OR, 3.20; 95%CI: 1.19-8.60).

CONCLUSIONS

T and b TaqI and BsmI alleles are protective against T1DM in Korean subjects.

Polymorphism rs2239185 in vitamin D receptor gene is associated with severe community-acquired pneumonia of children in Chinese Han population: a case-control study

Vitamin D receptor (VDR) is a potential candidate gene for community-acquired pneumonia (CAP). Examining the susceptibility VDR gene for CAP is essential for early intervention, prevention of related complications, and improvement of outcome. A case-control study was performed to examine the association between rs2239185 of VDR gene and CAP among children in Chinese Han population. Polymerase chain reaction and direct sequencing were used to genotype rs2239185 in 91 CAP children and 94 healthy children. For rs2239185, individuals with TT genotype showed a significantly higher risk of CAP than those with CC plus CT genotypes (P = 0.008). The occurrence of T allele of rs2239185 was significantly more frequent in CAP children than those in normal controls (P = 0.045).We found through stratification analysis that CAP children with systemic inflammatory response syndrome (SIRS), leukocyte count (WBC) >10 × 10(9)/L, C-reactive protein (CRP) >25 mg/L, procalcitonin (PCT) >2 ng/mL, and pediatric critical illness score <80 scores showed significantly higher frequency of TT genotype than those in normal controls (P = 0.0012, 0.0035, 0.0005, 0.0002, and 0.0021, respectively).

CONCLUSION

TT genotype of rs2239185 in VDR gene might be one of the potential genetic risk factors for CAP, and T allele of rs2239185 might be associated with the susceptibility to CAP and the severity of CAP.

Lack of association between vitamin D receptor gene ApaI, BsmI, and TaqI polymorphisms and primary biliary cirrhosis risk: a meta-analysis

Previous studies have reported the association between vitamin D receptor (VDR) polymorphisms and the risk of primary biliary cirrhosis (PBC), although these results remain controversial. The aim of this meta-analysis was to evaluate the association of three polymorphisms in VDR with PBC risk. The relevant studies were identified through an electronic database search carried out in September 2013. The crude odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the association between VDR polymorphisms and PBC risk. Six eligible studies which met our selection criteria were included. Overall, the ApaI, BsmI, and TaqI polymorphisms in the VDR gene were not associated with PBC risk (ApaI A vs a OR = 1.132, 95% CI = 0.870-1.472, p = 0.355; BsmI B vs b OR = 1.148, 95% CI = 0.697-1.891, p = 0.589; TaqI t vs T OR = 1.1432, 95% CI = 0.709-1.841, p = 0.584). Furthermore, in subgroup analysis by ethnicity for the ApaI, BsmI, and TaqI polymorphisms, there were no significant results in either Caucasians or Asians under the allele contrast and recessive and dominant models. This meta-analysis indicated that VDR polymorphisms were not a risk factor for PBC. Larger and more carefully designed studies are needed to verify our results.

Vitamin D receptor gene polymorphisms in multiple sclerosis patients in northwest Greece

BACKGROUND

Polymorphisms of the vitamin D receptor (VDR) gene have been linked to both multiple sclerosis (MS) and osteoporosis. We examined the frequency of the Taq-I and Bsm-I polymorphisms of the vitamin D receptor (VDR) gene in 69 patients with MS and 81 age and sex-matched healthy individuals. Genotyping of Taq-I (rs731236) and Bsm-I (rs1544410) was performed using TaqMan SNP Genotyping Assay. All patients and controls had determination of body mass index (BMI), bone mineral density (BMD) and smoking history.

RESULTS

The mean age of patients was 39 ± 10.5 years compared to 38.7 ± 10.7 years of the controls (p = 0.86), the BMI was 24.8 ± 4.2 kg/m2 compared to 25.7 ± 4.8 kg/m2 of the controls (p = 0.23), the BMD in the lumbar spine 0.981 ± 0.15 compared to 1.025 ± 013 of the controls (p = 0.06) and the total hip BMD was 0.875 ± 0.14 compared to 0.969 ± 0.12 of the controls (p < 0.001). There were no differences of the Taq-I (TT, CT, CC) and Bsm-I genotypes (GG, GA, AA) and allelic frequencies between MS and control individuals. Multivariate analysis also failed to show any association of the Taq-I and Bsm-I polymorphisms and MS or sex, BMI, BMD and smoking history.

CONCLUSIONS

This study suggests that the Taq-I and Bsm-I polymorphisms of the VDR gene are not associated with MS risk, BMI or BMD in the Greek population studied.

Vitamin D deficiency modulates Graves' hyperthyroidism induced in BALB/c mice by thyrotropin receptor immunization

TSH receptor (TSHR) antibodies and hyperthyroidism are induced by immunizing mice with adenovirus encoding the TSHR or its A-subunit. Depleting regulatory T cells (Treg) exacerbates thyrotoxicosis in susceptible BALB/c mice and induces hyperthyroidism in normally resistant C57BL/6 mice. Vitamin D plays an important role in immunity; high dietary vitamin D intake suppresses (and low intake enhances) adaptive immune responses. Vitamin D-induced immunosuppression may enhance Treg. Therefore, we hypothesized that decreased vitamin D intake would mimic Treg depletion and enhance hyperthyroidism induced by A-subunit adenovirus immunization. BALB/c mice had a reduced ability vs. C57BL/6 mice to generate the active metabolite of vitamin D (1,25-dihydroxyvitamin D3). Vitamin D deficiency induced subtle immune changes in BALB/c (not C57BL/6) mice. Compared with mice fed regular chow, vitamin D-deprived BALB/c mice had fewer splenic B cells and decreased interferon-gamma responses to mitogen and lacked memory T-cell responses to A-subunit protein. However, vitamin D deficiency did not alter TSHR antibody responses measured by ELISA, TSH binding inhibition, or cAMP generation from TSHR-expressing cells. Unexpectedly, compared with vitamin D-sufficient mice, vitamin D-deficient BALB/c mice had lower preimmunization T(4) levels and developed persistent hyperthyroidism. This difference was unrelated to the immunological changes between vitamin D-deficient or -sufficient animals. Previously, we found that different chromosomes or loci confer susceptibility to TSHR antibody induction vs. thyroid function. Our present studies provide evidence that an environmental factor, vitamin D, has only minor effects on induced immunity to the TSHR but directly affects thyroid function in mice.

Genetic association of vitamin D receptor polymorphisms with autoimmune hepatitis and primary biliary cirrhosis in the Chinese

BACKGROUND

Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are two autoimmune diseases of unknown etiology. Genetic factors appear to be involved in the pathogenesis of both diseases. Vitamin D has been shown to exert multiple immunomodulatory effects, which acts through its own receptor (VDR). Polymorphisms of VDR had been implicated in several autoimmune diseases. In the present study, the association between Chinese patients with AIH, PBC and the polymorphisms in exon 2, intron 8 and exon 9 of vitamin D receptor genes was studied.

METHODS

Four candidate gene loci were investigated in 49 patients with AIH, 58 patients with PBC, and 160 healthy controls. The VDR polymorphisms were assessed by FokI, BsmI, ApaI, and TaqI endonuclease digestion after specific polymerase chain reaction (PCR) amplification.

RESULTS

The result show a significant difference in FokI polymorphism between AIH patients and controls (chi(2) = 5.47, P = 0.019), and a significant association in BsmI polymorphisms between PBC patients and controls (chi(2) = 6.52, P = 0.01). Furthermore the distribution of FokI, BsmI, ApaI, and TaqI gene types differed between Chinese healthy controls and Caucasian healthy controls.

CONCLUSION

It is suggested that there is a genetic link of VDR polymorphisms to autoimmune liver diseases such as AIH and PBC in Chinese patients. Further studies are needed to elucidate the mechanisms by which VDR polymorphisms contribute to the lose of immune tolerance in autoimmune diseases.

The genetics of autoimmune thyroid disease

Autoimmune thyroid diseases (AITDs), such as Graves' hyperthyroidism, are common disorders involving multiple genes and the environment. Some pathogenetic genes are probably shared between these diseases and non-endocrine autoimmune diseases, whereas others are disease specific. Population studies show that major histocompatibility complex alleles and CTLA4 confer risk for AITDs. Genetic studies have identified over 20 potential loci; only one, mapping to 5q31, has been convincingly replicated. Despite its recent emergence as an autoimmunity gatekeeper gene, linkage of CLTA4 to AITDs was described in only one Caucasian population subset. Like in the case of many complex genetic disorders, identifying AITD pathogenetic genes is limited by the ability of data analysis methods to discern the influence of genes of minor effect in a relatively small database.

Association between AIDS disease progression rates and the Fok-I polymorphism of the VDR gene in a cohort of HIV-1 seropositive patients

In addition to its role in mineral metabolism, 1,25-dihydroxivitamin D3 (1,25(OH)2D3) also has immunomodulatory effects. Vitamin D receptor (VDR) mediates genomic actions of 1,25(OH)2D3, by acting as a transcription factor that modulates the expression of several 1,25(OH)2D3 response genes. Variations at the VDR locus have been associated with susceptibility and progression to several immune diseases. We investigated the association between rates of progression to acquired immunodeficiency syndrome (AIDS) and the Fok-I polymorphism, which is located at the initiation codon of the VDR gene. The study was performed with a cohort of 185 patients infected with human immunodeficiency virus type 1 (HIV-1): all belonged to the intravenous drug abuse risk group. Progression to AIDS was according to the Centers for Disease Control 1993 criterion (CDC-1993). In addition, a first drop in CD4 cell count to below 200 microL(-1) was considered as outcome. Patients who reached outcomes during follow-up were considered progressors. Non-progressors were those patients remaining outcome-free after a minimum follow-up of 8 years. Heterozygous at the Fok-I polymorphism were over-represented in the group of patients that progressed to AIDS CDC-1993 (50% of progressors versus 36% of non-progressors, P=0.061; risk ratio (RR)=1.38 (95% confidence interval (CI): 0.98-1.96)) and in the group of patients that showed a drop in CD4 cell count to below 200 microL(-1) (52% of progressors versus 36% of non-progressors, P=0.037; RR=1.44 (95% CI: 1.02-2.03)). Mean time to AIDS CDC-1993 was shorter for those with Ff genotype than for those with FF and ff genotypes (non-Ff genotype patients), (log rank test P=0.035; Cox hazard ratio (HR) for Ff versus non-Ff=1.53 (95% CI: 1.0-2.33), P=0.047). In addition the drop in CD4 cell count to below 200 microL(-1) was reached faster in Ff carriers than in non-Ff patients (log rank test P=0.015; HR for Ff versus non-Ff=1.77 (95% CI: 1.12-2.8), P=0.014). According to these results, HIV-1 seropositive patients carrying the Ff genotype could be considered prone to a faster progression to AIDS.

Lack of association of the vitamin D receptor gene with Graves' disease in UK Caucasians

OBJECTIVE

Vitamin D modulates the immune system by suppressing the proliferation of activated T cells, with its actions being directed through the vitamin D receptor (VDR). A number of single nucleotide polymorphisms (SNPs) have been identified in the VDR gene, of which several have been associated with autoimmune diseases, including type 1 diabetes and Graves' disease (GD) in Japanese females. The aim of this study was to test for association of polymorphisms of the VDR gene in the genetic susceptibility to GD in UK Caucasians.

DESIGN

Target DNA for five previously published SNPs, four novel SNPs and one microsatellite marker was amplified by the polymerase chain reaction (PCR). Subsequent genotyping was performed using restriction fragment length polymorphism (RFLP) or microsatellite genotyping analysis, according to the type of VDR polymorphism.

PATIENTS

We obtained DNA from a case-control dataset consisting of 768 patients with GD and 864 control subjects. All patients and control subjects were Caucasians born in the UK, and all gave informed, written consent.

MEASUREMENTS

Frequencies of the alleles and genotypes of the ten VDR gene polymorphisms were compared between patients and control subjects using the chi2 test. Odds ratios were calculated using Woolf's method with Haldane's modification for small numbers and D prime (D') was calculated to assess the level of linkage disequilibrium (LD) between the ten polymorphisms.

RESULTS

No differences in allele or genotype frequencies were observed between GD cases and control subjects for any of the nine SNPs studied. The S allele of the PolyA microsatellite marker was slightly more frequent in GD cases when compared with control subjects (chi2= 4.364, P = 0.04). Strongest LD between markers was observed towards the 3' end of the VDR gene but there was no evidence of association with disease.

CONCLUSION

This is the largest and most comprehensive study of the VDR gene in GD to date and these data suggest that these polymorphisms of the VDR gene do not contribute to GD susceptibility in the UK.

The genetics of autoimmune endocrine disease

The common autoimmune endocrinopathies result from an interaction between environmental factors and genetic predisposition. Several chromosomal gene regions have been shown to contribute to more than one disease, supporting the clinical observation that the autoimmune endocrine diseases cluster within individuals and families. Genetic studies have implicated the major histocompatability complex (MHC)-human leucocyte antigen (HLA) genes on chromosome 6p21, although this chromosomal region does not explain all of the genetic contribution to the various disorders. Non-MHC-HLA genes, including disease-specific loci, are beginning to be identified and the publication of the draft sequence of the human genome will undoubtedly expediate future discoveries. Combined with the establishment of large cohorts of subjects with disease and the development of technology capable of performing high-throughput genotyping, genetic studies are likely to impact on the future treatment and prevention of the common autoimmune endocrine diseases.

Current knowledge of Japanese type 1 diabetic syndrome

The Japanese have one of the lowest incidence of childhood type 1 diabetes in the world, but the incidence of this disease is clearly increasing within the Japanese population, as reported in several European countries. Latent autoimmune diabetes mellitus in adult (LADA) patients are also likely to have a lower incidence compared to Caucasians. Among the non-autoimmune (type 1B) diabetes in Japanese adults, there exists a novel subtype of type 1 diabetes characterized by extremely rapid onset and pancreatic exocrine inflammation. HLA and non-HLA gene associations to type 1 diabetes may vary depending on ethnic origin. Highly susceptible HLA haplotypes of type 1 diabetes observed in Caucasian patients are not found in Japanese patients, while protective HLA haplotypes are similar. Association studies of non-HLA genes have identified several candidate genes that influence the heterogeneity of disease phenotypes as well as disease susceptibility to type 1 diabetes. The INS-VNTR gene or polymorphisms of MICA gene are associated with susceptibility, whereas a certain allele of MICA gene and IL-10 gene polymorphism are associated with clinical heterogeneity of the disease. An expression of multiple autoantibodies to a biochemically determined autoantigen confers a high risk for progression to type 1 diabetes. The combined evaluation of multiple autoantibodies is more sensitive than is ICA testing for the diagnosis of type 1 diabetes. A high titer of GAD autoantibody has the predictive value of future insulin deficiency in patients with LADA. For accurate predictive strategies of future insulin deficiency, combinational multiple autoantibodies analysis or genetic determination should be considered for effective immune intervention.

Vitamin D receptor initiation codon polymorphism influences genetic susceptibility to type 1 diabetes mellitus in the Japanese population

BACKGROUND

Vitamin D has been shown to exert manifold immunomodulatory effects. Type 1 diabetes mellitus (T1DM) is regarded to be immune-mediated and vitamin D prevents the development of diabetes in the NOD mouse. We studied the association between T1DM and the initiation codon polymorphism in exon 2 of the vitamin D receptor gene in a Japanese population. We also investigated associations between the vitamin D receptor polymorphism and GAD65-antibody (Ab) positivity. We carried out polymerase chain reaction-restriction fragment length polymorphism analysis in 110 Japanese T1DM patients and 250 control subjects. GAD65 antibodies were assessed in 78 patients with T1DM.

RESULTS

We found a significantly higher prevalence of the F allele / the FF genotype in the patients compared to the controls (P = 0.0069 and P = 0.014, respectively). Genotype and allele frequencies differed significantly between GAD65-Ab-positive patients and controls (P = 0.017 and P = 0.012, respectively), but neither between GAD65-Ab-negative patients and controls (P = 0.68 and P = 0.66, respectively) nor between GAD65-Ab-positive and -negative patients (P = 0.19 and P = 0.16, respectively).

CONCLUSIONS

Our findings suggest that the vitamin D receptor initiation codon polymorphism influences genetic susceptibility to T1DM among the Japanese. This polymorphism is also associated with GAD65-Ab-positive T1DM, although the absence of a significant difference between GAD65-Ab-negative patients and controls might be simply due to the small sample size of patients tested for GAD65 antibodies.