Abstract
We examined our hypothesis that heme-oxygenase-1 (HO-1)-derived carbon monoxide (CO) inhibits the release of high-mobility group box 1 (HMGB1) in RAW264.7 cells activated with lipopolysaccharide (LPS) in vitro and in LPS- or cecal ligation and puncture (CLP)-induced septic mice in vivo, so that HO-1 induction or CO improves survival of sepsis in rodents. We found that pretreatment with HO-1 inducers (hemin, cobalt protoporphyrin IX) or transfection of HO-1 significantly inhibited HMGB1 release, which was blocked by HO-1 small interfering RNA, in cells activated by LPS. Carbon monoxide-releasing molecule 2 (CORM-2) but not bilirubin or deferoxamine inhibited HMGB1 release in LPS-activated macrophages. Oxyhemoglobin reversed the effect of HO-1 inducers on HMGB1 release. Translocation of HMGB1 from nucleus to cytosol was significantly inhibited by HO-1 inducers, CORM-2, or HO-1 transfection. Neutralizing antibodies to tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interferon-β, and Nω-nitro-l-arginine methyl ester hydrochloride but not N-[2-(cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide (NS-398) significantly inhibited HMGB1 release in LPS-activated cells. Production of TNF-α, IL-1β, and IFN-β was significantly reduced by pretreatment of HO-1 inducers, CORM-2, or HO-1 transfection in LPS-activated cells. Plasma levels of HMGB1 in mice challenged with LPS or CLP were significantly reduced by the administration of HO-1 inducers or CORM-2, which was accompanied by either reduction (pretreatment) or no change (delayed administration) of serum TNF-α and IL-1β levels. Regardless of pretreatment or delayed administration, CORM-2 and hemin rescued mice from lethal endotoxemia and sepsis induced by LPS or CLP. Taken together, we concluded that HO-1-derived CO reduces HMGB1 release in LPS-activated cells and LPS- or CLP-induced animal model of sepsis.
Footnotes
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This work was supported by the Medical Research Council program of Ministry of Science and Technology/Korea Science and Engineering Foundation [Grant R13-2006-012-01003-0].
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ABBREVIATIONS: HMGB1, high-mobility group box 1; HO-1, heme-oxygenase-1; CORM-2, carbon monoxide-releasing molecule II; LPS, lipopolysaccharide; CLP, cecal ligation and puncture; CoPPIX, cobalt protoporphyrin IX; COX, cyclooxygenase; DFO, deferoxamine mesylate; l-NAME, Nω-nitro-l-arginine methyl ester hydrochloride; iNOS, inducible nitric-oxide synthase; NS-398, N-[2-(cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide; siRNA, small interfering RNA; TNF-α, tumor necrosis factor-α; IL-1β, interleukin-1β; INF-β, interferon-β; ELISA, enzyme-linked immunosorbent assay; HbO2, oxyhemoglobin; DMSO, dimethyl sulfoxide.
- Accepted April 13, 2009.
- Received January 28, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
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