IL1RL1 and infection: Similar to the IL-33 treatment data, ST2−/− mice did not have more severe disease due to increased C. difficile bacterial burden or increased toxin levels, as there were no significant differences in C. difficile colonization or toxins A/B, and CDT levels between ST2−/− vs. controls on day 2 post infection when disease was most severe (Fig. 2f; Supplementary Fig. 3c, d).