Ischemia-reperfusion of rat myocardium activates nuclear factor-KappaB and induces neutrophil infiltration via lipopolysaccharide-induced CXC chemokine.
BACKGROUND
Mechanisms by which neutrophils are attracted to the myocardium in ischemia/reperfusion are not fully defined. Lipopolysaccharide-induced CXC chemokine (LIX), cytokine-induced neutrophil chemoattractant (KC), and macrophage inflammatory protein-2 (MIP-2) are rodent chemokines with potent neutrophil-chemotactic activity. The goals of the present study were to evaluate the roles of these chemokines in a rat model of ischemia/reperfusion and to examine the mechanisms of chemokine induction by oxidative stress and cytokines in cultured cardiomyocytes.


RESULTS
Male Wistar-Kyoto rats underwent 45 minutes of ligation of the left anterior descending coronary artery, followed by reperfusion for various periods. Compared with sham-operated controls, myocardium from reperfused animals had higher levels of free radicals, increased neutrophil infiltration evidenced histologically and by elevated myeloperoxidase activity, and increased nuclear factor (NF)-kappaB DNA binding activity. Ischemia-reperfusion also induced the expression of interleukin-1beta, tumor necrosis factor (TNF)-alpha, LIX, KC, and MIP-2 mRNA and protein. LIX expression was localized to resident myocardial cells, whereas KC and MIP-2 were expressed only in infiltrating inflammatory cells. Neutralization of LIX inhibited 79% of neutrophil infiltration into previously ischemic myocardium. In contrast, neutralization of KC and MIP-2 reduced neutrophil infiltration by only 28% and 37%, respectively. In cultured cardiomyocytes, LIX expression was induced by oxidative stress or TNF-alpha and was blocked by the NF-kappaB inhibitor pyrrolidinedithiocarbamate.


CONCLUSIONS
LIX is expressed by resident myocardial cells during ischemia-reperfusion and is induced in cultured cardiomyocytes by oxidative stress or TNF-alpha via NF-kappaB activation. Although KC and MIP-2 are expressed by inflammatory cells infiltrating the myocardium during reperfusion after ischemia, neutrophil recruitment to reperfused rat myocardium is mainly due to cardiomyocyte expression of LIX.
Chandrasekar
B
B
Department of Medicine, University of Texas Health Science Center at San Antonio, South Texas Veterans Healthcare System, Audie Murphy Division, San Antonio, Texas, USA. chandraseka@uthscsa.edu
Smith
J B
JB
Freeman
G L
GL
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002478:Cells, Cultured; D054426:Chemokine CXCL2; D019743:Chemokines, CXC / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002630:Chemotactic Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005609:Free Radicals / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006133:Growth Substances / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism; D008297:Male; D015846:Monokines / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017202:Myocardial Ischemia / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D009206:Myocardium / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D020556:Neutrophil Infiltration / Q000276:immunology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D015427:Reperfusion Injury / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
D000906:Antibodies; D054426:Chemokine CXCL2; D019743:Chemokines, CXC; D002630:Chemotactic Factors; C513296:Cxcl2 protein, rat; D005609:Free Radicals; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D007375:Interleukin-1; D015846:Monokines; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide