While CHI3L1 expression is undetectable in the Brp39 KO mice in any treated groups, low level of S100A9 expression can already be detected at steady state in these mice that significantly up-regulated during onset of acute DSS-induced colitis in a manner that is much higher than those of WT, which then subsequently decreased during the chronic phase of colitis. This evidence concerns the gene S100A9 and colitis.