Macrophage inflammatory protein-2 mediates the bowel injury induced by platelet-activating factor.
Platelet-activating factor (PAF) is a potent endogenous mediator of bowel inflammation. It activates neutrophils that are needed to initiate the inflammatory response. Macrophage inflammatory protein-2 (MIP-2), a critical C-X-C chemokine secreted by macrophages and epithelial cells, is a potent chemoattractant for neutrophils. Whereas MIP-2 has been previously shown to mediate the injury in various organs, its role in acute intestinal injury has never been assessed. In this study, we first investigated the effect of PAF on MIP-2 expression in the intestine. Anesthetized young adult male Sprague-Dawley rats were injected intravenously with either PAF (1.5 microg/kg) or saline. Sixty minutes later, ileal MIP-2 gene expression was determined by semiquantitative RT-PCR, and plasma and ileal MIP-2 protein was determined by ELISA. In a second step, we assessed the role of MIP-2 in PAF-induced bowel injury. Rats were pretreated with rabbit anti-rat MIP-2 antibodies or control IgG for 90 min and then injected intravenously with PAF (2.5 microg/kg) for 90 min. We found that, in the rat intestine, 1) MIP-2 mRNA was only minimally expressed constitutively in sham-operated animals; 2) MIP-2 mRNA was significantly upregulated in response to PAF; 3) MIP-2 protein plasma levels and local production of MIP-2 in the ileum were markedly induced by PAF; 4) the administration of anti-rat MIP-2 IgG, but not control rabbit IgG, markedly reduced PAF-induced bowel injury (injury scores of 0.19 +/- 0.09 vs. 1.12 +/- 0.43, P < 0.05), hypotension, and leukopenia but did not reduce PAF-induced hemoconcentration. Thus we conclude that MIP-2 mediates PAF-induced intestinal injury.
Department of Pediatrics, Children's Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60614, USA.
Xin-Bing
XB
Han
Xueli
X
Liu
Wei
W
Hsueh
Isabelle G
IG
De Plaen
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D054426:Chemokine CXCL2; D018925:Chemokines / Q000494:pharmacology; D019743:Chemokines, CXC / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006400:Hematocrit; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology; D007082:Ileum / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology*; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced* / Q000473:pathology; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics; D007958:Leukocyte Count; D007970:Leukopenia / Q000139:chemically induced; D008297:Male; D015846:Monokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics*; D020556:Neutrophil Infiltration / Q000187:drug effects; D009195:Peroxidase / Q000096:biosynthesis; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D019138:Antibodies, Blocking; D054426:Chemokine CXCL2; D018925:Chemokines; D019743:Chemokines, CXC; C513296:Cxcl2 protein, rat; D018836:Inflammation Mediators; D036341:Intercellular Signaling Peptides and Proteins; D015846:Monokines; D010972:Platelet Activating Factor; D012333:RNA, Messenger; D009195:Peroxidase