Background There is some evidence to suggest that IL-9 production in Th17 cells is pathogenic during autoimmunity. It is believed that this cytokine may be associated with the pathogenesis of rheumatologic autoimmune diseases, including systemic lupuserythematosus (SLE) and rheumatoid arthritis (RA).
Objectives The purpose of this article was to evaluate the levels of IL-9 in patients with SLE and RA compared with controls, and the association of IL-9 levels with clinical and laboratory parameters
Methods This was a cross-sectional study were was assessed 117 SLE patients, 67 RA patients and 24 healthy controls by ELISA. Clinical and laboratory parameters were recorded. Statistic analyzes were performed by Graph Prism 3.02 software.
Results The IL-9 serum levels were significantly higher in RA patients (4,77±3,618pg/ml) and in SLE patients (12,26±25,235 pg/ml) than in healthy individuals (1,22±0,706 pg/ml) (p<0,001). In SLE patients, there were no statistically significant associations or correlations between the levels of IL-9 and SLEDAI, number of ACR criteria, organ damage, clinical manifestations, complement consumption and ANA or anti-DNA positivity, with exception of disease time, which showed a statistically significant negative correlation with IL-9 levels (r=-0,1948; p=0,0378). In RA patients no association or statistically significant correlation was observed with disease duration, DAS28, HAQ, rheumatoid factor positivity or erosions on radiography.
Conclusions Few studies have evaluated the expression of Th9 cells or the levels of IL-9 in patients with autoimmune diseases, and it is unclear if there is an association with the pathogenesis of these diseases or if it is just an epiphenomenon. These data demonstrated increased serum levels of IL-9 in SLE and RA patients but further studies are needed to clarify the precise role of this cytokine and its potential use as therapeutic target.
Disclosure of Interest None declared