The IL33/ST2 axis in Sjogren syndrome in relation to disease activity

Primary Sjogren's Syndrome (pSS) is a systemic autoimmune disorder characterized by infiltration of the exocrine glands leading to secretory insufficiency. Despite the progress made in understanding the pathogenesis of the SS, many aspects remain to be clarified. Interleukin-33 (IL33) is a recently discovered cytokine, belonging to IL-1 superfamily. IL33 and its soluble receptor ST2 were implied in a number of immune and in autoimmune diseases pathogenesis. In this work ,we analyzed expression of IL33 and ST2 in Sjogren's syndrome.

Serum IL-33 and soluble ST2 were analyzed using commercial ELISA kit in 15 pSS, 9 patients with Systemic Lupus Erythematosus and 9 controls.

We found significant hyperexpression of sST2 in sera of SS patients and SLE patients compared to healthy subjects (p = 0.04 and p = 0.07, respectively). In pSS, sST2 levels in pSS positively correlated with activity index SSDAI (r = 0.662, p = 0.007). In SLE, we found positive correlation between ST2 and SLEDAI 2K (r = 0.685, p = 0.04). Circulating levels of IL-33 were detectable in 2 of 15 SS patients, in 2 SLE patients and in 1 of control subjects.

We found an hyperexpression of sST2 in pSS and SLE patients with a possible immune modulatory role, because of a substantial suppression of circulating IL33. In our pSS and SLE cohort, sST2 levels were in correlation with disease activity indices.