IL-1 beta-induced apoptosis in rat gastric enterochromaffin-like cells is mediated by iNOS, NF-kappa B and Bax protein

Background & Aims: Enterochromaffin-like (ECL) cells are histamine-containi ng endocrine cells in the gastric mucosa. Previous studies have shown that the proinflammatory cytokine interleukin (IL)-1 beta present during chronic gastritis inhibits histamine synthesis in ECL cells and leads to sustained functional impairment. This study investigated the effects of IL-1 beta on ECL cell apoptosis and the related signal-transduction mechanisms, Methods : ECL cells were isolated by pronase digestion and a combination of elutria tion, gradient centrifugation, and 48-hour culture (purity greater than or equal to 90%). Apoptosis was measured by terminal deoxynucleotidyl transfer ase-mediated deoxyuridine triphosphate nick-end labeling reaction and cell death detection enzyme-linked immunosorbent assay, Results: IL-1 beta (100 pg/ mi) increased the rate of programmed cell death 2-3 fold in ECL cells a fter 24 hours of incubation (total of 12%-14%), This effect was completely inhibited by the NF-kappa B inhibitor, proteasome inhibitor I, and the nitr ic oxide synthase inhibitor (iNOS) N-G-monomethyl-L-arginine (10(-4) mol/L) , but not by the caspase 3 inhibitor, Asp-Glu-Val-Asp-CHO. Western blot ana lysis, reverse-transcription polymerase chain reaction (PCR), and in situ P CR showed that IL-1 beta induced gene expression (after 2-4 hours) and prot ein synthesis (6-18 hours) of the iNOS isoform in ECL cells, Bar protein ex pression was increased in response to IL-1 beta, In contrast, bcl-2 gene ex pression was increased in response to basic fibroblast growth factor, which has been shown to counteract IL-1 beta- induced apoptosis. Conclusions: Th ese data suggest that IL-1 beta induces programmed cell death in isolated r at ECL cells via activation of NF-kappa B, iNOS, and the Bar protein.