Leptin （LEP） is a 16kDa peptide hormone produced mainly by white adipocyte tissue. Leptin is involved in maintaining gastric epithelial cell integrity and gastroprotection. In rats, systemic leptin is effective in attenuating both ethanol- and aspirin-induced damage to the gastric mucosa. This is correlated with an increase of leptin production by the stomach during experimentally-induced gastric damage in rats and during H pylori infection in humans. This gastric cytoprotective effect of leptin involves an increase in blood flow, local production of nitric oxide and prostaglandin E2, and vagus nerve-dependent mechanisms. One of the important functions of leptin is its role in the regulation of inflammatory processes. There is indeed a large body of evidence that leptin-mediated signal pathways play an active role in innate and adaptive immunity through alteration of various target genes transcription.