The promoter polymorphism −174G/C within the interleukin-6 gene (IL-6) has been reported to have a functional importance through the modulation of IL-6 gene expression in vitro and in vivo. IL-6 is thought to play an important role in autoimmune diseases and the effect of its receptor inhibitor—tocilizumab—has been recently studied. The aim of this case-control study was to investigate the association between the interleukin-6 −174G/C single nucleotide polymorphism and the susceptibility to dermatomyositis (DM) and systemic lupus erythematosus (SLE) in Bulgarian patients. Altogether, 87 patients—52 with SLE and 35 with DM—as well as 80 unrelated healthy controls were included in this study. All of them were analyzed by restriction fragment length polymorphism analysis (RFLP). The GG genotype and the G allele appeared to be associated with SLE, especially in women. None of the genotypes showed an association with DM. However, the G allele appeared to be associated with muscle weakness and it is a risk factor for elevated muscle enzymes. Our results indicate that IL-6 −174G/C polymorphism might be associated with the susceptibility to SLE especially in women. Although it is not associated with DM, it seems that IL-6 −174G/C polymorphism could modulate some clinical features in the autoimmune myopathies.

Polymorphisms in the cytokine genes and their natural antagonists are thought to influence the predisposition to dermatomyositis (DM) and systemic lupus erythematosus (SLE). A variable number tandem repeat (VNTR) polymorphism of 86 bp in intron 2 of the interleukin-1 receptor antagonist (IL-1RN) gene leads to the existence of five different alleles which cause differences in the production of both IL-1RA (interleukin-1 receptor antagonist) and IL-1β. The aim of this case-control study was to investigate the association between the IL-1RN VNTR polymorphism and the susceptibility to DM and SLE in Bulgarian patients. Altogether 91 patients, 55 with SLE and 36 with DM, as well as 112 unrelated healthy controls, were included in this study. Only three alleles were identified in both patients and controls ((1) four repeats, (2) two repeats, and (3) five repeats). The IL-1RN*2 allele (P=0.02, OR 2.5, and 95% CI 1.2–5.4) and the 1/2+2/2 genotypes were found prevalent among the SLE patients (P=0.05, OR 2.6, and 95% CI 1–6.3). No association was found between this polymorphism and the ACR criteria for SLE as well as with the susceptibility to DM. Our results indicate that the IL-1RN VNTR polymorphism might play a role in the susceptibility of SLE but not DM.

Introduction: The precise nature of dermatomyositis (DM) and systemic lupus erythematosus (SLE) is not yet fully understood, although it is recognized that various genetic, hormonal or external factors play a significant role in the onset of autoimmune processes. This study aims to explore the link between two specific genetic variants of the oncostatin M receptor (OSMR) – rs2278329 (Asp553Asn) and rs2292016 (-100G/T) – and the predisposition to DM and SLE in Bulgarian patients. Materials and methods: A total of 126 individuals were included in the study – 62 patients with SLE, 64 with DM, and 95 healthy unrelated controls. Genotyping was performed using TaqMan assays. Results: The analysis revealed that the minor allele frequency was low. None of the genetic variants investigated showed any significant correlation with SLE, DM, or clinical characteristics associated with these conditions. Conclusions: Our findings suggest that none of the OSMR genetic variants investigated pose a significant risk for the development of dermatomyositis or systemic lupus erythematosus in Bulgarian patients.