Intestinal NF-kappaB is activated, mainly as p50 homodimers, by platelet-activating factor.
NF-kappaB, a transcription factor, upregulates gene transcription of many inflammatory mediators. Here, we examined the activity of NF-kappaB in the rat small intestine, and how it may be affected by platelet-activating factor (PAF), an important mediator for intestinal injury and inflammation. Ileal nuclear extracts from sham-operated and PAF (1.5 microg/kg)-injected rats were prepared for the assessment of NF-kappaB DNA-binding activity, and the identification of NF-kappaB subunits. The experiment was also performed on neutrophil-depleted rats to examine whether the PAF effect is neutrophil-dependent. Cellular NF-kappaB was localized by immunohistochemistry. We found that: (a) NF-kappaB is constitutively active in rat small intestine; (b) PAF at a dose below that causing shock and bowel necrosis enhances DNA-binding activity of NF-kappaB within 30 min after injection; activated NF-kappaB contains predominantly p50 subunits; (c) immunohistochemistry showed that PAF induced translocation of p50 into the nucleus of cells of the lamina propria, as well as of the epithelium; and (d) the effect of PAF is abrogated by neutrophil depletion, suggesting a role of neutrophils in NF-kappaB activation. Our study suggests that NF-kappaB is weakly active constitutively in the intestine, and inflammatory stimuli such as PAF activate NF-kappaB and enhance its DNA-binding activity in the intestine, which contains predominantly p50 subunits.
De Plaen
I G
IG
Department of Pediatrics (Neonatology), Children's Memorial Hospital, Northwestern University Medical School, 2300 Children's Plaza, Chicago, IL 60614, USA.
Tan
X D
XD
Chang
H
H
Qu
X W
XW
Liu
Q P
QP
Hsueh
W
W
D000818:Animals; D001692:Biological Transport; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D019281:Dimerization; D004847:Epithelial Cells / Q000648:ultrastructure; D007082:Ileum / Q000648:ultrastructure; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000737:chemistry*; D008297:Male; D016328:NF-kappa B / Q000032:analysis / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D009504:Neutrophils / Q000502:physiology; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D010972:Platelet Activating Factor; D004247:DNA