Association of vitamin D receptor gene BsmI B/b and FokI F/f polymorphisms with adult dermatomyositis and systemic lupus erythematosus

A review of the critical role of vitamin D axis on the immune system

In recent years, the physiological and molecular functions of vitamin D (Vit-D) have been deeply investigated. At first, Vit-D was considered a regulator of mineral and skeletal homeostasis. However, due to the extensive-expression pattern of Vit-D receptor (VDR) in almost every non-skeletal cell, Vit-D is considered mainly a multifunctional agent with broad effects on various tissues, notably the immune system. The expression of VDR in immune cells such as dendritic cells, monocyte/macrophage, neutrophils, B cells and T cells has been well demonstrated. Besides, such immune cells are capable of metabolizing the active form of Vit-D which means that it can module the immune system in both paracrine and autocrine manners. Vit-D binding protein (DBP), that regulates the levels and homeostasis of Vit-D, is another key molecule capable of modulating the immune system. Recent studies indicate that dysregulation of Vit-D axis, variations in the DBP and VDR genes, and Vit-D levels might be risk factors for the development of autoimmune disease. Here, the current evidence regarding the role of Vit-D axis on the immune system, as well as its role in the development of autoimmune disease will be clarified. Further insight will be given to those studies that investigated the association between single nucleotide polymorphisms of DBP and VDR genes with autoimmune disease susceptibility.

Inflammatory Bowel Diseases Are Associated with Polymyositis and Dermatomyositis-A Retrospective Cohort Analysis

Background and Objectives: Polymyositis and dermatomyositis (PM/DM) are classified as polygenic autoimmune diseases, whereas inflammatory bowel disease (IBD) is considered a polygenic autoinflammatory disease. In the literature, several cases exist reporting the co-occurrence of both conditions. At the molecular level, PM/DM and IBD share common genetic determinants including interferon regulatory factor and vitamin D receptor susceptibility loci. Accumulating evidence underline several indicators that confer poor prognosis in IBD, including antinuclear antibody positivity and the presence of other autoimmune diseases, therefore the aim of this study is to assess the association between these entities. Materials and Methods: This is a population-based retrospective study using data retrieved from a large electronic medical record in Israel, the Clalit health registry. The sample included PM/DM patients and age- and sex-frequency matched controls. The prevalence of IBD in PM/DM was compared between the two groups and logistic regression was applied to control for confounding variables. Predictors of IBD in patients with PM/DM were also explored. Results: Our study included 12,278 subjects with 2085 PM/DM patients and 10,193 age- and sex- frequency-matched controls. The incidence of IBD in patients with PM/DM was significantly higher even after controlling for various confounding variables (OR of 1.73, 95% CI 1.05-2.86, p-value = 0.033). Anti-nuclear antibodies (ANA) positivity was found to be an independent predictor for IBD diagnosis in patients with PM/DM (OR 3.67, 95% CI 1.01-13.36, p = 0.048). Conclusion: Our analysis reports an association between IBD and PM/DM. Such association could point towards a common pathophysiological background. Further research is needed to further describe the clinical courses and whether a unique therapeutic approach is warranted.

Vitamin D Receptor (VDR) Genetic Variants: Relationship of FokI Genotypes with VDR Expression and Clinical Disease Activity in Systemic Lupus Erythematosus Patients

Vitamin D (VD) deficiency is more frequent in systemic lupus erythematosus (SLE) patients than in control subjects (CS); genetic variants in the VD receptor (VDR) could contribute to the clinical disease activity. This study was aimed to determine the association of the VDR variants FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) with susceptibility to the disease, VD status, VDR mRNA expression, and clinical disease activity in SLE patients. A cross-sectional study was conducted in 194 SLE and 196 CS Mexican women. Immunoassays quantified serum calcidiol and calcitriol. Genotyping was performed by allelic discrimination assays and mRNA VDR expression by qPCR. The FokI variant was not in linkage disequilibrium with BsmI, ApaI, and TaqI VDR variants. SLE patient carriers of the TT FokI genotype showed higher clinical disease activity scores. Notably, the mRNA VDR expression was higher in SLE patients vs. CS, in active vs. inactive SLE patients, and in participants of both study groups with vitamin D deficiency, higher calcitriol levels, and TT FokI genotype carriers. In conclusion, the TT FokI VDR genotype was related to high VDR expression and clinical disease activity in systemic lupus erythematosus patients.

Environmental Risks for Inflammatory Myopathies

This is an up-to-date review on external environmental factors for adult-onset idiopathic inflammatory myopathies (IIMs). Environmental factors with suggestive evidence including ultraviolet radiation, smoking, infectious agents (viruses in particular), pollutants, medications (ie, statin) and vitamin D deficiency are discussed. We also discuss the potential implications of environmental factors in IIM development, identify current challenges, and provide insight into future investigations.

Differential distribution of vitamin D receptor (VDR) gene variants and its expression in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disorder that displays an important genetic background. Vitamin D₃ (VD₃ ) through its receptor (VDR) plays an important immunomodulatory role in autoimmune misbalance, being capable of modulating immune responses. Genetic alterations in VDR gene may contribute to an altered risk in SLE development and clinical manifestations. We investigated VDR SNPs (single nucleotide polymorphisms) frequencies in 128 SLE patients and 138 healthy controls (HC) and mRNA differential expression in 29 patients and 17 HC regarding SLE susceptibility as well as clinical features. We observed that rs11168268 G allele (OR = 1.55, p = .01) and G/G genotype (OR = 2.69, p = .008) were associated with increased SLE susceptibility. The rs2248098 G allele and A/G and G/G genotypes were associated to lower SLE susceptibility (OR = 0.66, p = .01; OR = 0.46, p = .01; OR = 0.44, p = .02, respectively). Regarding clinical features, we observed lower risk for: rs11168268 A/G genotype and nephritis (OR = 0.31, p = .01); rs4760648 T/T genotype and photosensitivity (OR = 0.24, p = .02); rs1540339 T/T genotype and antibody anti-dsDNA (OR = 0.19, p = .015); rs3890733 T/T genotype and serositis (OR = 0.10, p = .01). We identified a significant downregulation in VDR expression levels when compared patients and controls overall (p = 1.04e^-7 ), in Cdx-2 A/G and G/G (p = .008 and p = .014, respectively) and in patients with nephritis (p = .016) Our results suggested that VDR SNPs influence upon SLE susceptibility and in particular clinical features, acting on mRNA expression in SLE patients overall and the ones with nephritis.

Impact of Vitamin D Receptor Gene Polymorphism on Systemic Lupus Erythematosus Susceptibility: A Pooled Analysis

Background: This study was designed to evaluate the influence of vitamin D receptor (VDR) gene polymorphisms on systemic lupus erythematosus (SLE) susceptibility. Methods: All eligible investigations were identified, the number of the various genotypes in the case and control groups were reviewed. A pooled analysis was performed using the Stata software. The study was carried out according to the Ethics Review Committee of The Third Xiangya Hospital, Central South University. Results: This meta-analysis included 19 studies. In our analysis, the VDR Apal polymorphism was correlated with SLE susceptibility in the overall population (AA vs. aa: odds ratio [OR] = 1.374, 95% confidence interval [CI]: 1.115-1.692, p = 0.003; AA + Aa vs. aa: OR = 1.342, 95% CI: 1.139-1.583, p < 0.01). The VDR Bsml and Apal polymorphisms were correlated with SLE susceptibility in Caucasian subjects (BB vs. Bb + bb: OR = 0.734, 95% CI: 0.593-0.909, p = 0.005; B vs. b: OR = 0.865, 95% CI: 0.760-0.983, p = 0.026; AA vs. aa: OR = 1.329, 95% CI: 1.016-1.740, p = 0.038). The VDR BsmI and FokI polymorphisms were correlated with SLE in African subjects (B vs. b: OR = 1.898, 95% CI: 1.458-2.470, p＜0.01; BB + Bb vs. bb: OR = 2.935, 95% CI: 1.944-4.430, p < 0.01; FF vs. Ff + ff: OR = 2.424, 95% CI: 1.673-3.512, p < 0.01; F vs. f: OR = 1.720, 95% CI: 1.417-2.087, p < 0.01; FF vs. ff: OR = 3.154, 95% CI: 2.083-4.774, p < 0.01; FF + Ff vs. ff: OR = 1.803, 95% CI: 1.363-2.384, p < 0.01). In addition, the VDR Apal polymorphism was correlated with SLE in female subjects (AA vs. aa: OR = 1.392, 95% CI: 1.049-1.849, p = 0.022) when stratified by gender. But there was no association between the VDR TaqI polymorphism and SLE susceptibility in our analysis. Conclusions: The VDR Apal polymorphism was associated with SLE susceptibility in general populations; in addition, Apal polymorphism was associated with SLE in female subjects. The VDR Bsml gene polymorphism was correlated with SLE susceptibility in Caucasian and African populations, whereas the VDR FokI polymorphism was correlated with SLE in African populations. But there was no association between the VDR TaqI polymorphism and SLE susceptibility in our analysis.

Association of Vitamin D Metabolism Gene Polymorphisms with Autoimmunity: Evidence in Population Genetic Studies

A high prevalence of vitamin D (calcidiol) serum deficiency has been described in several autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (AR), and systemic lupus erythematosus (SLE). Vitamin D is a potent immunonutrient that through its main metabolite calcitriol, regulates the immunomodulation of macrophages, dendritic cells, T and B lymphocytes, which express the vitamin D receptor (VDR), and they produce and respond to calcitriol. Genetic association studies have shown that up to 65% of vitamin D serum variance may be explained due to genetic background. The 90% of genetic variability takes place in the form of single nucleotide polymorphisms (SNPs), and SNPs in genes related to vitamin D metabolism have been linked to influence the calcidiol serum levels, such as in the vitamin D binding protein (VDBP; rs2282679 GC), 25-hydroxylase (rs10751657 CYP2R1), 1α-hydroxylase (rs10877012, CYP27B1) and the vitamin D receptor (FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) VDR). Therefore, the aim of this comprehensive literature review was to discuss the current findings of functional SNPs in GC, CYP2R1, CYP27B1, and VDR associated to genetic risk, and the most common clinical features of MS, RA, and SLE.

Differential distribution in vitamin D receptor gene variants and expression profile in Northeast Brazil influences upon active pulmonary tuberculosis

Tuberculosis is an infectious disease with variable outcomes. This variability is due to host immune capacity in containing the infection process initiated by the Mycobacterium tuberculosis (MTB). Vitamin D is able to modulate a very specific immune response against MTB infection, and its action relies on vitamin D receptor (VDR) binding. Altered VDR forms may compromise vitamin D pathway and proper immune response after MTB infection. Herein we assessed the relationship of five potentially functional polymorphisms from VDR: rs2228570 FokI, rs11568820 Cdx-2, rs2248098, rs1540339 and rs4760648, with tuberculosis susceptibility. The SNP rs4760648 T/T was associated with differential susceptibility to tuberculosis (OR = 2.50, 95%CI = 1.20-5.36, p = 0.01). The SNP rs1540339 presented association to both T allele (OR = 0.55, 95%CI = 0.35-0.88, p = 0.01) and the T/T genotype (OR = 0.404, 95%CI = 0.20 - 0.78, p = 0.005). The FokI T allele was identified as associated to diminished susceptibility (OR = 0.67, 95% CI = 0.45-0.99, p = 0.04) to active TB, as well as T/T genotype (OR = 0.15, 95%CI = 0.04-0.45, p = 9.58 × 10^-5). We also performed the expression analyses and observed a down-regulation of VDR in patients (-10.717 FC, p = 8.42e^-12), and according to the presence of associated FokI SNP, we observed that the C/T and T/T genotypes presence increases VDR expression (+ 1.25 and + 2.35 FC, p = 0.425 and p = 0.506, respectively). This study shows that vitamin D receptor variants can influence upon pulmonary tuberculosis susceptibility and VDR mRNA levels are decreased in those patients.

Vitamin D receptor FokI, TaqI, and ApaI polymorphisms and susceptibility to systemic lupus erythematosus: an updated meta-analysis

This study aimed to explore whether vitamin D receptor (VDR) polymorphisms are associated with susceptibility to systemic lupus erythematosus (SLE). Meta-analyses were conducted to determine the associations between the VDR FokI, TaqI, and ApaI polymorphisms and SLE in all subjects and each ethnic group. A total of 12 studies were considered in the meta-analysis, which involved 1974 patients and 2506 controls. Meta-analysis of the VDR FokI polymorphism showed no association between SLE and the FokI F allele in all study subjects (OR = 1.047, 95% CI = 0.781-1.403, p = 0.758). However, the meta-analysis showed a significant association between SLE and the VDR FokI F allele in the Arab population (OR = 1.721, 95% CI = 1.417-2.088, p < 0.001). Analysis using the recessive and dominant models and homozygote contrast showed the same pattern for the VDR FokI F allele in Europeans, Asians, and Arabs. This meta-analysis showed that polymorphisms in VDR FokI, TaqI, and ApaI are not associated with SLE susceptibility in overall, European and Asian populations. However, the VDR FokI polymorphism is associated with SLE susceptibility in the Arab population.

Increased Cumulative Incidence of Dermatomyositis in Ulcerative Colitis: a Nationwide Cohort Study

On a molecular level, two autoimmune diseases: ulcerative colitis (UC) and dermatomyositis share common genetic determinants. On a clinical level, case reports evidenced the co-occurrence of these two diseases. We therefore hypothesize that UC is potentially associated with increased cumulative incidence of dermatomyositis. The goals of this retrospective cohort study were to evaluate whether UC is associated with increased cumulative incidence of dermatomyositis independent of sex and age. For comparison, we also assessed the cumulative incidence of polymyositis in UC and control subjects. The study enrolled 3,133 UC subjects and 14,726 control subjects. The cumulative incidence of dermatomyositis was significantly higher in UC than that of control subjects (p = 0.026), but the cumulative incidence of polymyositis was comparable between UC and control subjects (p = 0.596). UC was independently associated with the increased incident dermatomyositis (hazard ratio: 6.19, 95% confidence interval = 1.77-21.59, p = 0.004) after adjusting for sex, age, and concomitant rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis. Similar trends of increased dermatomyositis in UC were observed when patients were stratified based on sex and age. In conclusion, our findings suggest that UC is probably associated with increased cumulative incidence of dermatomyositis, independent of sex, age, and concomitant autoimmune diseases.