Soluble ST2 is a sensitive clinical marker of ulcerative colitis evolution

Background: The ST2/IL-33 pathway has been related to ulcerative colitis (UC), and soluble ST2 (sST2), to disease severity. We tested the potential usefulness of sST2 as a predictive marker of treatment response and patients' outcome. Methods: Twenty-six patients with active UC were prospectively recruited and grouped according to an endoscopic score and therapy response. Colonoscopic biopsies were collected at baseline and 6 months or when patients showed clinical activity. The protocol was reinitiated in patients requiring rescue therapy. Blood and stool were collected at baseline, 1, 3, 6 and 12 months. Serum and mucosal ST2, and fecal calprotectin (FC) content were determined by ELISA and correlated to Mayo clinical and endoscopic subscore. Intestinal ST2 was evaluated by immunofluorescence. Wilcoxon signed rank test and Spearman correlations (Rs) were applied (p < 0.05). Results: Follow-up was completed in 24 patients. sST2 levels (median and range) varied from 173.5 [136.6-274.0] to 86. 5 [54.6-133.2] in responders (p < 0.05), and 336.3 [211.0-403.2] to 385.3 pg/mL [283.4-517.3] in non-responders at baseline and 6 months, respectively. sST2 levels correlated with Mayo clinical and endoscopic subscore, mucosal ST2 and FC (Rs = 0.57, 0.66, 0.74 and 0.42, respectively; p < 0.0001) and showed a trend similar to that of FC in responders. Non-responders revealed an increased ST2 content, restricted to the lamina propria's cellular infiltrate. Conclusions: Consecutive sST2 measurement to follow changes in inflammatory activity of UC patients who respond or not to treatment identifies sST2, like FC, as a useful biomarker in predicting clinical outcome of UC patients.