IL-17A and IL-17F polymorphisms in rheumatoid arthritis and Sjogren's syndrome

The aim of this study was to evaluate the influence of Th17 polymorphisms on the susceptibility or severity of rheumatoid arthritis (RA) and Sjogren's syndrome (SS). The study sample comprised 206 individuals of both genders divided into three groups: exclusive rheumatoid arthritis (RA-100 patients), rheumatoid arthritis and Sjogren's syndrome (RA/SS-31 patients), and healthy controls (C-75 individuals). All the individuals were submitted to clinical evaluation, unstimulated sialometry, and Schirmer test; some patients with RA were also submitted to minor salivary gland biopsy for definition of SS diagnosis. Saliva samples were collected for isolation of DNA and genotyping of Th17 genes; IL-17A (-197G/A) and IL-17F (7488T/C). IL-17A (-197G/A) and IL-17F (7488T/C) SNPs were not associated with susceptibility to RA or secondary SS (sSS, p > 0.05 for both SNPs). In addition, they did not influence RA activity or clinical markers of SS. IL-17A (-197G/A) and IL-17F (7488T/C) polymorphisms are not associated with the susceptibility nor to the severity of RA and sSS in the studied population. A better understanding of the pathogenesis of SS is demanded to an adequate treatment as well as to the development of new management strategies.