Leptin and its receptor in normal human gastric mucosa and in Helicobacterpylori-associated gastritis

Background: Leptin, a newly discovered weight-reducing hormone, is mainly p roduced in fat cells. Recently, this hormone has been reported to be produc ed in rat gastric mucose cells. In the present study we analyzed the locali zation and expression of leptin and its receptors in normal human gastric m ucosa and in patients with Helicobacter pylori-associated gastritis. Method s: Plasma leptin levels and gastric mucose leptin content were determined i n 39 patients with dyspepsia. Cellular localization of leptin and of the si gnaling receptor (Ob-R-L) were assessed by immunohistochemistry. Reverse tr anscriptase polymerase chain reaction (RT-PCR) for leptin receptor isoforms was performed on gastric epithelial cells isolated by laser-capture-microd issection. Results: Leptin content of the corpus gastric mucosa in H. pylor i-negative group patients was significantly increased (4.6 +/- 1.2, n = 15) as compared with the H. pylori-negative group (2.5 +/- 0.5 pg/mg, n = 24, P = 0.006). The presence of leptin immunoreactivity was shown in the lower half of corpus epithelial glands. By RT-PCR no leptin mRNA was detectable i n human gastric tissue. In contrast, expression of both Ob-R-L and the lept in receptor isoforms could be detected in gastric epithelial cells. Leptin receptor protein was detected throughout the mucosa. Conclusions: Leptin it self is stored and secreted but not produced in human gastric mucosa. The f unctional receptor and all isoforms are present in human gastric mucosa. H. pylori-associated gastritis leads to significant increases in local leptin concentration in the gastric corpus.