IL-10, IL-12B and IL-17 gene polymorphisms in patients with mixed connective tissue disease

Objectives: Mixed connective tissue disease (MCTD) is a rare systemic autoimmune disease with a prevalence of about 10 cases/100,000. It seems that in the pathogenesis of MCTD no individual cytokines/cells, but rather an altered pattern of these markers altogether may contribute to the autoimmune processes and their balance determines disease activity. IL-10, IL-12 and IL-17F as inflammatory cytokines might be an important functional candidate genes for autoimmune diseases including MCTD.

Methods: The study group consisted of 66 patients with MCTD and of 106 (163 for IL-12B) healthy individuals. SNPs in the IL-10 (- 592C/A, - 1082G/A), IL-12B (+ 1188A/C) and IL-17F (His161Arg, Glu126Gly) genes were investigated by PCR-RFLP approach.

Results: The frequency of the IL-10-592A and -1082A allele was higher in MCTD patients than in control groups (both p = 0,0000). In addition the -1082G/A IL-10 gene polymorphism was associated with esophageal involvement and with anti-U1-A and -C antibodies. The IL-17 7488A/G variant showed correlation with presence of anti-SmB and anti-dsDNA antibodies, while the IL-17F 7383A/G variant was associated with Sjögren's syndrome and leuco-and thrombocytopenia. Moreover, the IL-12 SNP + 1188A/C showed correlation with sclerodactyly in MCTD patients.

Conclusion: Present findings indicate that IL-10 gene variants may be considered as genetic risk factors for MCTD susceptibility.