Suppression of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide by peroxisome proliferator-activated receptor gamma activation.

Abstract

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a nuclear transcription factor that regulates the expression of genes associated with inflammation. We applied the animal model of H. pylori lipopolysaccharide(LPS)-induced gastritis to assess the effect of a specific PPAR-gamma ligand, ciglitazone, on the apoptotic processes and the mucosal activity of inducible nitric oxide synthase (NOS-2), and the expression of COX-1 and -2 cyclooxygenases. In the absence of ciglitazone, the LPS-elicited mucosal inflammatory responses were accompanied by a massive epithelial cell apoptosis, upregulation of NOS-2 and COX-2 protein expression, and a marked increase in the mucosal PGE2 generation and NOS-2 activity. The expression of COX-1 protein, however, remained unchanged. Administration of ciglitazone led to dose-dependent reduction (up to 48%) in the severity of mucosal inflammatory involvement elicited by the LPS and this effect of the agent was reflected in a 72.5% reduction in apoptosis, a 58.7% decline in the mucosal PGE2 generation and a 75.6% drop in NOS-2 activity, and produced a marked decrease inCOX-2 and NOS-2 protein expression. Our findings demonstrate that PPAR-gamma activation suppresses gastric mucosal inflammatory responses to H. pylori LPS, and suggest that pharmacological manipulation of PPAR-gamma activation may provide therapeutic benefits in the resolution of inflammation associated with H. pylori infection.