S100A9 and inflammatory bowel disease: In turn, genetic inactivation of S100a9 protected against experimental enteritis and colitis, and pharmacologic inhibition of S100A9 ameliorated chronic colitis.<h4>Conclusions</h4>Collectively, this study links the detection of fecal S100A9 dimers with clinical and endoscopic disease activity in IBD and identifies inflammatory actions of S100A8 and S100A9 homodimers in the intestine.