Polymorphisms of interleukin-31 are associated with anti-CCP levels in females with rheumatoid arthritis.

Abstract

Cytokines play important roles in a wide range of different cell types, tissues and organs. Interleukin-31 (IL-31) is a member of the IL-6 family of cytokines. IL-31 is a T helper type 2 (Th2) effecter cytokine that plays an important role in atopic and allergic diseases. It was found that genotype and allele frequencies of the IL-31 SNPs in rheumatoid arthritis (RA) patients were not significantly different from those in the healthy controls. The haplotype frequencies of IL-31 SNPs were also not significantly different between the RA patients and the healthy controls. The g.-1066G>A, g.586C>A and g.1449C>G polymorphisms of IL-31 were significantly associated with the anti-CCP levels in the female RA patients (P = 0.010, 0.012 and 0.025, respectively). The results indicate that in RA patients, IL-31 SNPs may play a role in anti-CCP production, and suggest that SNPs in the IL-31 gene could be associated with susceptibility to RA. RA is one of the most common autoimmune diseases worldwide and is characterized by the inflammation of synovial tissues and the formation of rheumatoid pannus, which is capable of eroding adjacent cartilage and bone and cause subsequent joint destruction (Goldring and Gravallese 2000). RA comes about through a complex interaction betweenmultiple genetic and environmental factors (Gregersen 1999). The activated T helper (Th) cells during the developing stage are differentiated phenotypically and functionally into two distinct types of cells, Th1 and Th2 (Abbas et al. 1996). Th1 cells produce cytokines such as interferonγ (IFN-γ ), IL-12 and the cytotoxic factor lymphotoxin. They are commonly associated with cell-mediated immune