title: S100A8 and S100A9 mediate endotoxin-induced cardiomyocyte dysfunction via the receptor for advanced glycation end products.
abstract: Cardiovascular dysfunction as a result of sepsis is the leading cause of death in the critically ill. Cardiomyocytes respond to infectious pathogens with a Toll-like receptor-initiated proinflammatory response in conjunction with a decrease in contractility, although the downstream events linking Toll-like receptor activation and reduced cardiac contractility remain to be elucidated. Using microarray analysis of cardiac tissue exposed to systemic lipopolysaccharide (LPS), we discovered that 2 small calcium-regulating proteins (S100A8 and S100A9) are highly upregulated. HL-1 cardiomyocytes, isolated primary cardiomyocytes, and live mice were exposed to LPS, whereas beating HL-1 cells had S100A8 and S100A9 overexpressed and their calcium flux quantified. Using in vivo microbubble technology, we delivered S100A8 and S100A9 to normal mouse hearts; using the same technology, we inhibited S100A9 production in mouse hearts and subsequently exposed them to LPS. Coimmunoprecipitation of S100A8 and S100A9 identified interaction with RAGE (the receptor for advanced glycation end products), the cardiac function and postreceptor signaling of which were investigated. HL-1 cardiomyocytes, isolated primary cardiomyocytes, and whole hearts exposed to LPS have large increases in S100A8 and S100A9. Cardiac overexpression of S100A8 and S100A9 led to a RAGE-dependent decrease in calcium flux and, in the intact mouse, to a decreased cardiac ejection fraction, whereas knockdown of S100A9 attenuated LPS-induced cardiac dysfunction. Cardiomyocytes exposed to LPS express S100A8 and S100A9, leading to a RAGE-mediated decrease in cardiomyocyte contractility. This finding provides a novel mechanistic link between circulating pathogen-associated molecular products and subsequent cardiac dysfunction.
authors.affiliation: Critical Care Research Laboratories, St. Paul' Hospital, University of British Columbia, Vancouver, Canada. jboyd@mrl.ubc.ca
authors.forename: John H
authors.initials: JH
authors.lastname: Boyd
authors.forename: Bernard
authors.initials: B
authors.lastname: Kan
authors.forename: Haley
authors.initials: H
authors.lastname: Roberts
authors.forename: Yingjin
authors.initials: Y
authors.lastname: Wang
authors.forename: Keith R
authors.initials: KR
authors.lastname: Walley
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D040501:Calgranulin A; D040502:Calgranulin B / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D004452:Echocardiography; D006331:Heart Diseases / Q000000981:diagnostic imaging / Q000276:immunology / Q000378:metabolism*; D047468:Immunoprecipitation; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D009200:Myocardial Contraction / Q000276:immunology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism*; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D018805:Sepsis / Q000276:immunology / Q000378:metabolism; D013318:Stroke Volume / Q000276:immunology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
chemical_list: D040501:Calgranulin A; D040502:Calgranulin B; D008070:Lipopolysaccharides; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D009418:S100 Proteins; C086145:S100a8 protein, mouse; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium