title: In vivo and in vitro modulation of intercellular adhesion molecule (ICAM)-1 expression by hypertonicity.
abstract: Hepatic ischemia-reperfusion (I/R) is an important cause of organ dysfunction in the critically ill. With reperfusion, Kupffer cells release pro-inflammatory cytokines that promote endothelial cell (EC) expression of adhesion molecules such as intercellular adhesion molecule (ICAM)-1, facilitating neutrophil (PMN) infiltration. Studies suggest hypertonic saline (HTS) might exert beneficial effects on development of organ injury following shock on the basis of reduced PMN-EC interactions. We hypothesized that HTS alters expression of EC ICAM-1 and thus minimizes PMN-mediated injury. To test our hypothesis, we used an in vivo model of hepatic I/R and an in vitro model of activated EC. Rats underwent 30 min of hepatic ischemia after pretreatment with HTS (7.5% NaCl, 4cc/kg ia) or normal saline (NS). At 4 h reperfusion, plasma was taken for aspartate aminotransferase (AST) and liver tissue was harvested for assessment of hepatic ICAM-1 mRNA by Northern blot analysis. Human umbilical vein endothelial cells (HUVECs) were activated by lipopolysaccharide (LPS) and exposed to hypertonic medium (350-500 mOsM). HUVEC ICAM-1 protein was measured by cell ELISA and ICAM-1 mRNA by Northern blot analysis. HTS prevented hepatic I/R injury as measured by AST. AST of shams was 282.6+/-38.1 IU/L. I/R following NS pretreatment caused significant injury (AST 973.8+/-110.9 IU/L) compared to sham (SM) (P < 0.001). Pretreatment with HTS exerted significant protection following I/R with an AST of 450.9+/-56.3 IU/L (P < 0.05). There was no significant difference in AST levels between SM and HTS groups. Reduced hepatic injury after HTS and I/R was accompanied by inhibition of I/R-induced hepatic ICAM-1 mRNA expression compared to NS treated animals (P < 0.01). Similarly, hypertonicity inhibited HUVEC LPS-induced ICAM-1 protein (LPS: 1.86+/-0.19 absorbance units; 400 mOsM +/- LPS: 1.45+/-0.14 absorbance units; 450 mOsM + LPS: 1.02+/-0.19 absorbance units, P < 0.001) and mRNA expression. Thus, hypertonicity modulates endothelial ICAM-1 expression as one possible protective mechanism against I/R injury.
authors.affiliation: Department of Surgery, Toronto General Hospital and University of Toronto, Ontario, Canada.
authors.forename: G D
authors.initials: GD
authors.lastname: Oreopoulos
authors.forename: J
authors.initials: J
authors.lastname: Hamilton
authors.forename: S B
authors.initials: SB
authors.lastname: Rizoli
authors.forename: J
authors.initials: J
authors.lastname: Fan
authors.forename: Z
authors.initials: Z
authors.lastname: Lu
authors.forename: Y H
authors.initials: YH
authors.lastname: Li
authors.forename: J C
authors.initials: JC
authors.lastname: Marshall
authors.forename: A
authors.initials: A
authors.lastname: Kapus
authors.forename: O D
authors.initials: OD
authors.lastname: Rotstein
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D007511:Ischemia / Q000188:drug therapy / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000188:drug therapy / Q000378:metabolism; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*
chemical_list: D008070:Lipopolysaccharides; D012462:Saline Solution, Hypertonic; D018799:Intercellular Adhesion Molecule-1; D007770:L-Lactate Dehydrogenase