IL-33 determines enhanced blood coagulation during intestinal inflammation. (A-F) WT mice were induced with DSS colitis and examined at indicated time points. (A) Time to cessation of bleeding in response to tail injury. (B) Platelet counts during DSS colitis. (C) Representative histograms of fluorescence intensity of CD62P and Jon/A for platelets treated with or without thrombin. (D) Quantification of geometric mean fluorescence intensity (MFI) in panel C. (E) 5-HT levels in serum were assessed by ELISA. (F) IL-33 levels in colonic tissue were assessed by ELISA. (G-I) Il33^−/− mice were induced with DSS colitis and examined at indicated time points. (G) Time to cessation of bleeding in response to tail injury. (H) Representative histograms of fluorescence intensity of CD62P and Jon/A for platelets treated with or without thrombin between WT and Il33^−/− mice. (I) Quantification of geometric MFI in panel H. Data are representative of 2 independent experiments (C,H) or are pooled from 2 independent experiments (A-B, D-G, I). *P < .05, **P < .01, ***P < .001 by Student t test. Error bars represent standard deviation.