Are key cytokines genetic and serum levels variations related to rheumatoid arthritis clinical severity?

This study evaluated the possible association between SNPs in cytokines coding genes, namely IL10, IL6 and IFNG, cytokines serum levels and clinical assessment' scores in patients with Rheumatoid Arthritis(RA). SNPs genotyping was performed in 126 RA patients and 177 healthy individuals with Taqman probes specific for IL10 -1082 (T>C, rs1800896);INFG -1616 (A>G, rs2069705) and IL6 -174 (G>C, rs1800795) variants,positioned in regulatory regions. Cytokine Bead Array (CBA) was used to measure cytokine levels. We found association between INFG -1616 G allele(p = 0.0210; OR = 1.605) and INFG -1616 GG genotype (p = 0.0268; OR =2.609) and RA susceptibility. We also observed association between IL10 -1082 TT genotype and high clinical disease activity index (CDAI) values (p = 0.026; OR = 1.906; 95% CI = 1.082 - 3.359), IL10 -1082 CC genotype and low CDAI values (p = 0.016; OR = 0.256) and INFG -1616 AA and high CDAI values (p = 0.025; OR = 2.919). IL10 -1082 CC also exhibited the lowest IL-10 levels than IL10 -1082 TT (p = 0.020) and IL10 -1082 TC (p = 0.032). Finally, we verified higher IL-6 value in the RA patients than healthy control group (p = 0.007) and an association between high IL-6 levels and increased CDAI (r = 0.4648, p = 0.0015); DAS 28 (r = 0.3933, p= 0.0091), presence of bone erosions (r = 0.3170, p = 0.0361), ESR levels(r = 0.3041, p = 0.0448) and IFN-γ levels (r = 0.3049, p = 0.0468).Altogether, we suggest that IL10 -1082 (T>C, rs1800896) and INFG -1616(A>G, rs2069705) polymorphisms as well as IL-6 levels alterations may play a role for prognostic and disease follow-up.