Background and Objectives: Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune, multi-factorial disease, in which environmental and genetic factors play a major role. RA is possibly linked to vitamin D deficiency and vitamin D receptor (VDR) gene polymorphisms, and research demonstrates that FokI variant susceptibility is associated with increased disease risk among Caucasians. The aim of this study was to evaluate vitamin D deficiency prevalence and its correlation to RA clinical parameters, and to determine the possible association of VDR gene polymorphisms and RA susceptibility in the Lithuanian population. Materials and Methods: Overall, 206 RA patients and 180 age- and sex-matched healthy controls were enrolled at Vilnius University Hospital Santaros Klinikos after informed consent was obtained. The disease activity score 28 C-reactive protein (DAS28 CRP), rheumatoid arthritis impact of disease (RAID) score, and health assessment questionnaire (HAQ) were recorded in RA patients, and 25(OH)D serum levels were evaluated by chemiluminescent microparticle immunoassay for all subjects. Four VDR gene polymorphisms, BsmI, FokI, ApaI, and TaqI, were assessed using real-time PCR instruments and genotyping assays in both groups. Results: The study registered a high prevalence of 25(OH)D deficiency (<50 nmol/L) in RA patients (61.55% (n = 127)). The mean serum concentration in RA patients (44.96 ± 21.92 (nmol/L)) was significantly lower than in the healthy controls (54.90 ± 22.82 (nmol/L)), p < 0.0001. A significant inverse correlation between vitamin D level, DAS28 CRP, and HAQ scores was confirmed in RA patients, with p < 0.05. Still, there was no significant association between the overall risk of RA disease for any allele or genotype of the four VDR loci tested. Conclusions: The study confirmed that vitamin D deficiency is prevalent among RA patients and the 25(OH)D level is significantly lower compared with healthy controls. Lower vitamin D concentration was related with increased disease activity and disability scores. However, genetic analysis of four VDR polymorphisms did not confer the susceptibility to RA in Lithuanian population.
Background: Rheumatoid arthritis (RA) is an autoimmune inflammatory disease with complex etiopathogenesis launched by multiple risk factors, including epigenetic alterations. RA is possibly linked to vitamin D that is epigenetically active and may alter DNA methylation of certain genes. Therefore, the study aimed to evaluate the relationship between DNA methylation status of vitamin D signaling pathway genes (VDR, CYP24A1, CYP2R1), vitamin D level and associations with RA.Materials and Methods: Totally 76 participants (35 RA patients and 41 healthy controls) were enrolled from a case-control vitamin D and VDR gene polymorphisms study regarding age and vitamin D concentration. CpG islands in promoter regions of the VDR, CYP24A1, CYP2R1 genes were chosen for DNA methylation analysis by means of pyrosequencing. Chemiluminescent microplate immunoassay was used to assess 25(OH)D serum levels. RA clinical data, i.e. the disease activity score C-reactive protein 28 (DAS28 – CRP) as well as patient-reported outcome questionnaires were recorded.Results: The study showed similar methylation pattern in the promoter regions of vitamin D pathway genes in RA and control group with p>0.05 (VDR gene 2.39% vs. 2.48%, CYP24A1 gene 16.02% vs. 15.17% and CYP2R1 2.53% vs. 2.41%). CYP24A1 methylation intensity was significantly higher in compare to methylation intensity of VDR and CYP2R1 genes in both groups (p<0.0001). A tendency of higher vitamin D concentration in cases having methylated VDR (57.57±28.93 vs. 47.40±29.88 nmol/l), CYP24A1 (53.23±26.22 vs. 48.23±34.41 nmol/l) and CYP2R1 (60.41±30.73 vs. 44.54±27.63 nmol/l) genes and a positive correlation between VDR, CYP2R1 methylation intensity and vitamin D level in RA affected participants was revealed (p>0.05). A significantly higher CYP24A1 methylation intensity (p=0.0104) was detected in blood cells of vitamin D deficient (<50 nmol/l) RA patients vs. vitamin D deficient controls.Conclusions: Our data suggests some indirect associations between DNA methylation status of vitamin D pathway genes and vitamin D level in RA.
Background:Vitamin D is known for its immunomodulatory and epigenome interacting effects. Vitamin D deficiency is frequently observed in rheumatoid arthritis (RA) patients compared to healthy controls, is also named as a potential risk factor in RA ethiopatogenesis and may alter DNA methylation of certain genes [1,2]. Still, causality of vitamin D deficiency in RA patients needs to be elucidated.Objectives:The aim of the study was to evaluate relationship between DNA methylation status of vitamin D related genes (VDR,CYP24A1,CYP2R1), miRNA-155 expression, vitamin D level and its association with RA.Methods:CpG islands in promoter region of theVDR,CYP24A1,CYP2R1genes were chosen for DNA methylation analysis by means of pyrosequencing. DNA from blood mononuclear cells of 31 RA patients and 31 age and sex matched healthy controls was assessed for methylation pattern after informed consent was obtained in Vilnius university Hospital Santaros klinikos Centre of Rheumatology. For miRNA analysis quantitative reverse transcription PCR was used. Chemiluminescent microplate immunoassay was used to asses 25(OH)D serum levels.Results:25(OH)D concentrations varied from deficiency (<50 nmol/l), insufficiency (50-75 nmol/l) to normal range (≥75-100 nmol/l) in RA (mean 47.49 nmol/l; SD ± 27.93) and healthy controls (mean 57.38 nmol/l; SD ± 29.93)).CYP24A1methylation level was significantly higher in comparison toVDR(p<0.0001) andCYP2R1(p<0.0001) genes in both groups.CYP24A1hypermethylation was also observed in older subjects (p=0.012). The study demonstrated a significant positive correlation between vitamin D concentration andVDR,CYP2R1genes methylation intensity (r2=0.31, p=0.014; r2=0.25, p=0.042, respectively). However, gene methylation frequency and methylation intensity showed no significant difference between RA patients and healthy controls (VDR– 2.4vs2.6 %,CYP24A1– 16.6vs15.3 %,CYP2R1– 2.6vs2.6 %) (p>0.05). To note, miRNA-155 expression negatively correlated withCYP24A1methylation intensity (r2=-0.43, p=0.009).Conclusion:Our study identified significant associations between theVDRandCYP2R1promoter methylation and vitamin D concentration. However, no significant differences in DNA methylation pattern between RA patients and healthy controls were detected. MiR-155 expression was associated withCYP24A1methylation level, confirming its possible involvement in vitamin D metabolism. The data of our study suggests that epigenetic phenomena are significantly involved in vitamin D metabolism and may have an indirect effect on RA ethiopatogenesis.References:[1]Jeffery LE, et al. Nat Rev Rheumatol. 2016,12.4:201.[2]Fetahu IS et al. Front Physiol. 2014,5:164.Acknowledgments:This project has received funding from the Research Council of Lithuania (LMTLT), agreement No. S-MIP-17-12.Disclosure of Interests:None declared
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