Since the microbiota is shaped by IL-1β signaling, we examined the Tregs in Nlrp3R258W mice on the Il1r1−/− background and found that Tregs in these mice were reduced to those seen in WT (Fig. 7c); this also correlated with severity of colitis (Fig. 6e) and so suggests a crucial role for Tregs in microbiota-mediated protection of mice from colitis. Here, IL1B is linked to colitis.