Gender-Specific Effects of Genetic Variants within Th1 and Th17 Cell-Mediated Immune Response Genes on the Risk of Developing Rheumatoid Arthritis

The present study was conducted to explore whether single nucleotide polymorphisms (SNPs) in Th1 and Th17 cell-mediated immune response genes differentially influence the risk of rheumatoid arthritis (RA) in women and men. In phase one, 27 functional/tagging polymorphisms in C-type lectins and MCP-1/CCR2 axis were genotyped in 458 RA patients and 512 controls. Carriers of Dectin-2(rs4264222T) allele had an increased risk of RA (OR = 1.47, 95% CI 1.10-1.96) whereas patients harboring the DC-SIGN(rs4804803G), MCP-1(rs1024611G), MCP-1(rs13900T) and MCP-1(rs4586C) alleles had a decreased risk of developing the disease (OR = 0.66, 95% CI 0.49-0.88; OR = 0.66, 95% CI 0.50-0.89; OR = 0.73, 95% CI 0.55-0.97 and OR = 0.68, 95% CI 0.51-0.91). Interestingly, significant gender-specific differences were observed for Dectin-2(rs4264222) and Dectin-2(rs7134303): women carrying the Dectin-2(rs4264222T) and Dectin-2(rs7134303G) alleles had an increased risk of RA (OR = 1.93, 95% CI 1.34-2.79 and OR = 1.90, 95% CI 1.29-2.80). Also five other SNPs showed significant associations only with one gender: women carrying the MCP-1(rs1024611G), MCP-1(rs13900T) and MCP-1(rs4586C) alleles had a decreased risk of RA (OR = 0.61, 95% CI 0.43-0.87; OR = 0.67, 95% CI 0.47-0.95 and OR = 0.60, 95% CI 0.42-0.86). In men, carriers of the DC-SIGN(rs2287886A) allele had an increased risk of RA (OR = 1.70, 95% CI 1.03-2.78), whereas carriers of the DC-SIGN(rs4804803G) had a decreased risk of developing the disease (OR = 0.53, 95% CI 0.32-0.89). In phase 2, we genotyped these SNPs in 754 RA patients and 519 controls, leading to consistent gender-specific associations for Dectin-2(rs4264222), MCP-1(rs1024611), MCP-1(rs13900) and DC-SIGN(rs4804803) polymorphisms in the pooled sample (OR = 1.38, 95% CI 1.08-1.77; OR = 0.74, 95% CI 0.58-0.94; OR = 0.76, 95% CI 0.59-0.97 and OR = 0.56, 95% CI 0.34-0.93). SNP-SNP interaction analysis of significant SNPs also showed a significant two-locus interaction model in women that was not seen in men. This model consisted of Dectin-2(rs4264222) and Dectin-2(rs7134303) SNPs and suggested a synergistic effect between the variants. These findings suggest that Dectin-2, MCP-1 and DC-SIGN polymorphisms may, at least in part, account for gender-associated differences in susceptibility to RA.