Histological analysis of the colon tissues from IgG-treated colitis mice showed severe inflammation with superficial ulceration, crypt destruction, mucosal damage, and leukocyte infiltration of epithelium and LP, whereas the administration of either anti-S100a9 Ab or anti-TNFα Ab alleviated histological colonic damage, and had preferential effect on histological subscores for inflammatory infiltrate and epithelial damage in colon tissues (Figures 2A,B). This evidence concerns the gene S100A9 and colitis.