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Epigenetic Alterations in Juvenile Spondyloarthritis Patients: a Preliminary Study of Selected Genes Promoter Methylation and Silencing

Juvenile spondyloarthritis (jSpA) is a complex disease with both genetic and environmental factors contributing to etiology. Multiple studies have shown that epigenetic mechanisms could link the environment and gene expression and thus provide a potential explanation for external contribution in the pathogenesis of numerous diseases, including rheumatic. Previously obtained gene signatures in jSpA patients revealed distinctive expression of important immune- related genes, though the mechanism(s) responsible for those alterations remained unknown. The purpose of this study was to evaluate the methylation levels of the TLR4, CXCR4, NLRP3, and PTPN12 gene promoter, along with the expression of several non- coding microRNAs (miR-150, miR-146a, miR-181a, and miR-223) in jSpA patients. Peripheral blood samples were obtained from 19 patients newly diagnosed with jSpA according to ILAR classification criteria for enthesitis- related arthritis (ErA) and seven gender- and age- matched subjects without any symptoms or signs of inflammatory disease. The expression of specific microRNAs was analyzed using qRT-PCR with predeveloped microRNA assays. DNA promoter region methylation status of selected genes was assessed by methylated DNA immunoprecipitation (MeDIP) analysis. Fold enrichment of immunoprecipitated DNA differed significantly for NLRP3 promoter site, while the expression analysis of selected microRNAs showed no significant difference in fold change between jSpA patients and healthy controls. The results indicated that epigenetic modifications in the initial phase of the disease could be responsible for some of the expression alterations in jSpA patients. Since NLRP3 has a crucial role in inflammasome assembly and inflammasomes have been shown to shape microbiota, it is tempting to assume that dysbiosis in jSpA patients can at least partially be explained by reduced NLRP3 expression due to hypermethylation, stressing for the first time the epigenetic contribution to jSpA pathophysiology.

Juvenile spondyloarthritis ; jSpA ; Enthesitis-related arthritis ; ErA ; Epigenetics ; DNA promoter methylation ; microRNA

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