title: Inhibition of LPS toxicity by hepatic argininosuccinate synthase (ASS): novel roles for ASS in innate immune responses to bacterial infection.
abstract: Lipopolysaccharide (LPS), a structural component of Gram-negative bacteria, is implicated in the pathogenesis of endotoxemia/sepsis and multi-organ injury, including liver damage. We have shown that argininosuccinate synthase (ASS), a hepatic enzyme of the urea cycle, accumulates in circulation within 1h after treatment with both LPS alone and hepatotoxic combination of LPS and D-Galactosamine. These findings indicate ASS as a sensitive biomarker of liver responses to bacterial endotoxin. Furthermore, we suggest that the ASS release represents a potential counteracting liver reaction to LPS, and demonstrates anti-LPS activity of recombinant ASS (rASS) in vitro and in rodent models of endotoxemia in vivo. rASS physically bound to LPS, as indicated by a gel shift assay, and suppressed Escherichia coli growth in cultures consistent with direct antimicrobial properties of ASS. rASS reduced LPS cytotoxicity, TNF-α production, and increased cell viability in cultured mouse macrophages, even when added one hour following LPS challenge. Intraperitoneal injection of rASS (5 mg/kg) after treatment with a high dose of LPS remarkably increased survival of rodents, with a concomitant decrease of sepsis markers TNF-α, C-reactive protein (CRP), and lactate dehydrogenase (LDH) levels in blood. These results suggest that the endogenous ASS constitutes a novel liver-derived component of the innate immune response to bacterial LPS, and that recombinant ASS could mitigate the lethal effects of bacterial endotoxins during sepsis.
authors.affiliation: Center of Innovative Research, Banyan Biomarkers, Inc., Alachua, FL 32615, USA. vprima@banyanbio.com
authors.forename: Victor
authors.initials: V
authors.lastname: Prima
authors.forename: Alvin
authors.initials: A
authors.lastname: Wang
authors.forename: Gabriel
authors.initials: G
authors.lastname: Molina
authors.forename: Kevin K W
authors.initials: KK
authors.lastname: Wang
authors.forename: Stanislav I
authors.initials: SI
authors.lastname: Svetlov
mesh_terms: D000818:Animals; D001124:Argininosuccinate Synthase / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D001424:Bacterial Infections / Q000276:immunology* / Q000378:metabolism; D002097:C-Reactive Protein / Q000037:antagonists & inhibitors; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D019446:Endotoxemia / Q000097:blood / Q000276:immunology / Q000378:metabolism; D004731:Endotoxins / Q000276:immunology / Q000378:metabolism; D004926:Escherichia coli / Q000276:immunology / Q000378:metabolism; D005688:Galactosamine / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology*; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors / Q000097:blood; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000633:toxicity; D008099:Liver / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism
chemical_list: D004731:Endotoxins; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D005688:Galactosamine; D002097:C-Reactive Protein; D007770:L-Lactate Dehydrogenase; D001124:Argininosuccinate Synthase