IL-1beta-induced apoptosis in rat gastric enterochromaffin-like cells is mediated by iNOS, NF-kappaB, and Bax protein.
OBJECTIVE
Enterochromaffin-like (ECL) cells are histamine-containing endocrine cells in the gastric mucosa. Previous studies have shown that the proinflammatory cytokine interleukin (IL)-1beta present during chronic gastritis inhibits histamine synthesis in ECL cells and leads to sustained functional impairment. This study investigated the effects of IL-1beta on ECL cell apoptosis and the related signal-transduction mechanisms.


METHODS
ECL cells were isolated by pronase digestion and a combination of elutriation, gradient centrifugation, and 48-hour culture (purity >/=90%). Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling reaction and cell death detection enzyme-linked immunosorbent assay.


RESULTS
IL-1beta (100 pg/mL) increased the rate of programmed cell death 2-3 fold in ECL cells after 24 hours of incubation (total of 12%-14%). This effect was completely inhibited by the NF-kappaB inhibitor, proteasome inhibitor I, and the nitric 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 analysis, reverse-transcription polymerase chain reaction (PCR), and in situ PCR showed that IL-1beta induced gene expression (after 2-4 hours) and protein synthesis (6-18 hours) of the iNOS isoform in ECL cells. Bax protein expression was increased in response to IL-1beta. In contrast, bcl-2 gene expression was increased in response to basic fibroblast growth factor, which has been shown to counteract IL-1beta- induced apoptosis.


CONCLUSIONS
These data suggest that IL-1beta induces programmed cell death in isolated rat ECL cells via activation of NF-kappaB, iNOS, and the Bax protein.
Mahr
S
S
Department of Medicine II, Technical University of Munich, Munich, Germany.
Neumayer
N
N
Gerhard
M
M
Classen
M
M
Prinz
C
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D003546:Cysteine Endopeptidases / Q000187:drug effects; D004759:Enterochromaffin Cells / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D006640:Histidine Decarboxylase / Q000235:genetics; D007375:Interleukin-1 / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000187:drug effects; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D009842:Oligopeptides / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein; D019323:omega-N-Methylarginine / Q000494:pharmacology
C494828:Bax protein, rat; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D009097:Multienzyme Complexes; D016328:NF-kappa B; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; C108637:aspartyl-glutamyl-valyl-aspartal; D051028:bcl-2-Associated X Protein; D016222:Fibroblast Growth Factor 2; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C505410:Casp3 protein, rat; D053148:Caspase 3; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D006640:Histidine Decarboxylase