Intestinal NF-κB is activated, mainly as p50 homodimers, by platelet-activating factor

• Published in: Biochimica et biophysica acta. Lipids and lipid metabolism Vol. 1392; no. 2; pp. 185 - 192
• Main Authors: De Plaen, Isabelle G., Tan, Xiao-Di, Chang, Hong, Qu, Xiao-Wu, Liu, Qian-Ping, Hsueh, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.1998
• Subjects: Nuclear factor-κB; Platelet-activating factor; Small intestine; PMN, polymorphonuclear leukocytes; TNF, tumor necrosis factor-α; Platelet-activating factor; Ab, antibody; mAb, monoclonal antibody; Nuclear factor-κB; Small intestine; DTT, dithiothreitol; PMSF, phenylmethylsulfonyl fluoride; NF-κB, nuclear factor-κB; IL, interleukin; LPS, lipopolysaccharide; PAF, platelet-activating factor; EMSA, electrophoretic mobility shift assay
• ISSN: 0005-2760; 1879-145X
• DOI: 10.1016/S0005-2760(98)00024-1

NF-κB, a transcription factor, upregulates gene transcription of many inflammatory mediators. Here, we examined the activity of NF-κB 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 μg/kg)-injected rats were prepared for the assessment of NF-κB DNA-binding activity, and the identification of NF-κB subunits. The experiment was also performed on neutrophil-depleted rats to examine whether the PAF effect is neutrophil-dependent. Cellular NF-κB was localized by immunohistochemistry. We found that: (a) NF-κB 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-κB within 30 min after injection; activated NF-κB 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-κB activation. Our study suggests that NF-κB is weakly active constitutively in the intestine, and inflammatory stimuli such as PAF activate NF-κB and enhance its DNA-binding activity in the intestine, which contains predominantly p50 subunits.