An hypothetical model of influence of PPARγ expression in ulcerative colitis. Induction of PPARγ expression in epithelial cells by bacterial lipopolysaccharide- (LPS-) activated TLR4, in turn leads to break NFB and MAPK pathways to produce inflammatory mediators. The reduced expression of PPARγ together with TLR4 upregulation might enhance the inflammatory mediators production thus resulting in mucosal damage.