In Vivo Disruption of the Fas Pathway Abrogates Gastric Growth Alterations Secondary toHelicobacterInfection

Helicobacter infection is associated with gastric cell growth alterations, plausibly predisposing to ulcer disease and gastric adenocarcinoma. Previous investigations from our laboratory have implicated the involvement of the Fas pathway in Helicobacter-induced apoptotic signaling in vitro. In this report we use C57BL/6J00064 mice to examine the direct role of Fas signaling in Helicobacter-mediated growth alterations in vivo. Helicobacter infection up-regulated gastric cell Fas antigen (Fas Ag) mRNA and increased surface receptor expression, along with concomitant altered apoptotic and proliferative response, measured by terminal deoxytransferase-deoxyuridine 5'-triphosphate nick end labeling and 5-bromo-2'-deoxuridine immunohistochemistry, respectively. In addition, histopathological alterations, including parietal cell loss and gastric atrophy, were noted. In contrast, infection in B6. MRL-FAS(lpr), a Fas Ag knockout mouse in the C57BL/6 background, did not result in increased apoptosis, proliferation, or histological alterations, a finding that argues strongly for the role of Fas-signaling pathway in orchestrating diverse growth responses to Helicobacter infection.