Assessment of interleukin 6 gene polymorphisms with rheumatoid arthritis

Rheumatoid arthritis (RA) is complex autoimmune system disease and significant impact on the health of population in our world. Numerous studies confirmed that genetic factors play a crucial role in the pathogenesis of RA. In this current study, we aimed to investigate IL-6 polymorphisms and RA risk in Chinese Han population.

508 RA patients and 494 age- and gender- matched healthy controls were recruited, all subjects were genotyped with an Agena MassARRAY platform. Subsequently, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression after adjusting for age and gender.

Our results suggested that IL-6 rs2243289 allele and genotype frequencies were associated with reduced RA risk under all genetic models (all p < 0.05). Stratification analysis revealed that IL-6 rs2243289 polymorphism was significant associated with decreased the risk of RA in the old groups (age > 54) (all p < 0.05). However, IL-6 rs2069837 and rs1800796 polymorphisms were associated with increased risk of RA among the young groups (age ≤ 54) (all p < 0.05). In addition, subgroup analysis by gender suggested that IL-6 rs2069837 and rs1800796 polymorphism were interacted with increased the risk of RA in males (all p < 0.05). Besides, IL-6 rs2243289 was associated with reduced RA risk in females.

In conclusion, our results demonstrated the correlation between IL and 6 polymorphisms and RA susceptibility and confirmed for the first time that the relationship was restricted to age and gender in Chinese Han population.