Involvement of tumor necrosis factor alpha in intestinal epithelial cell proliferation following Paneth cell destruction.
BACKGROUND
An intravenous injection of diphenylthiocarbazone (dithizone), a zinc chelator, induces selective killing of Paneth cells which have a large amount of zinc in their cytoplasmic granules. A transient wave of intestinal epithelial cell proliferation occurs at 12 h after the injection. Paneth cells have tumor necrosis factor (TNF)-alpha protein in their cytoplasmic granules, and TNF-alpha has a proliferative effect on intestinal epithelial cells in vitro. The aim of this study is to clarify the in vivo role of TNF-alpha in intestinal epithelial cell proliferation using a dithizone-treated rat model.


METHODS
Male Wistar rats received a dithizone (100 mg/kg of body weight) injection with or without TNF-alpha inhibitor, pentoxifylline (100 mg/kg), neutralizing anti-TNF-alpha antibody (2 mg/kg), or nuclear transcription factor kappaB (NF-kappaB) inhibitors: pyrrolidine dithiocarbamate (100 mg/kg) or N-acetyl-L-cystein (100 mg/kg). The activation of NF-kappaB was examined by the electrophoretic mobility shift assay, and cellular proliferation by BrdU labeling.


RESULTS
Without any inhibitors, dithizone treatment evoked NF-kappaB activation in the ileal mucosa with its peak level at 2 h after the injection. TNF-alpha inhibition reduced the NF-kappaB activation, and blocked a transient wave of epithelial cell proliferation 12 h after the injection. NF-kappaB inhibitors also reduced the NF-kappaB activation and epithelial cell proliferation.


CONCLUSIONS
TNF-alpha released from degenerated Paneth cells was, in part, responsible for the intestinal cell proliferation through the activation of NF-kappaB, suggesting its proliferative effect on intestinal epithelial cells.
Seno
H
H
Dept. of Pathology, Kyoto University Graduate School of Medicine, Japan.
Sawada
M
M
Fukuzawa
H
H
Morita-Fujisawa
Y
Y
Takaishi
S
S
Hiai
H
H
Chiba
T
T
D000818:Animals; D002455:Cell Division; D002470:Cell Survival; D004230:Dithizone / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology; D007150:Immunohistochemistry; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D019879:Paneth Cells / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D004230:Dithizone