Does Novel IL-33 Correlates with TNF-α in RA and SLE ?

Abstract

Background: Production of high amounts of inflammatory cytokines plays direct role in disease pathogenesis, including that of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Objectives: To investigate whether serum levels of novel IL-33 and TNF-α are higher in Egyptian RA and SLE patients than controls and to compare serum levels of the novel IL-33 with TNF-α in RA and SLE with assessing their correlation to clinical disease activity and laboratory findings. Methodology: 24 SLE, 25 RA and 25 controls were enrolled in this study. Disease activity was evaluated using SLEDAI for SLE patients and DAS 28 for RA patients. IL-33 and TNF-α serum levels were determined using sandwich enzyme immunoassay. Results: A significant statistical difference of IL-33 level between SLE & RA groups (P=0.002) and between SLE & control groups existed (P<0.001). However, a non-significant difference existed between RA & control groups (P=0.340). There was a significant statistical difference of TNF-α level between SLE & control groups (P<0.001) and between RA & control groups (P<0.001), which didn't exist between RA & SLE groups (P=0.070). A significant positive correlation of serum IL-33 level with serum TNF-α level in SLE patients occurred (r=0.505, P=0.012), which was not found in RA (r=-0.023, P=0.912) or in the controls (r=-0.168, P=0.601). A significant positive correlation was found between TNF-α level and SLE patients with high disease activity (r=0.446 , P=0.029), which didn't exist with IL-33 (r=0.227, P=0.286). There was no correlation between serum IL-33 and DAS 28 (r=0.205, P=0.326), however a negative correlation occurred with TNFα (r=-0.404, P=0.045). Conclusion: Serum levels of TNF-α and novel IL-33 were higher in RA and SLE Egyptian patients than controls. A significant positive correlation occurred between serum IL-33 and serum TNF-α in SLE but not in RA patients. Most clinical and laboratory variables in RA and SLE patients did not correlate with either serum IL-33 or TNF-α levels.