DSS experiments

Acute colitis was induced by providing a 6 day course of DSS (Alfa aesar J63606-22) in drinking water at a concentration of 1%, 2% or 3% (g/dL, weight per volume). DSS solution was replaced every three days. On 10 day long DSS experiments, drinking water was replaced with autoclaved water as indicated on experimental figures. Mice of different genotypes were cohoused at the time of DSS experiments. Weight was recorded on a daily basis. Disease activity index (DAI) was calculated on day seven in a blinded fashion by adding individual scores from stool consistency, presence of blood in stool and weight change, as previously described (Supplementary file 3) (Cooper et al., 1993).