Protection of transplant-induced hepatic ischemia/reperfusion injury with carbon monoxide via MEK/ERK1/2 pathway downregulation.
Carbon monoxide (CO), a product of heme degradation by heme oxygenases (HO), has been shown to provide cytoprotection in various tissue injury models. This study examined the efficacy and molecular mechanisms of exogenously delivered inhaled CO in protecting liver grafts from cold ischemia/reperfusion (I/R) injury associated with liver transplantation. Orthotopic syngenic liver transplantation (OLT) was performed in Lewis rats with 18-h cold preservation in University of Wisconsin solution. Recipients were exposed to air or different concentrations of CO (20-250 ppm) for 1 h before and 24 h after OLT and killed 1-48 h posttransplant. CO inhalation significantly decreased serum alanine transaminase (ALT) levels and suppressed hepatic necrosis and neutrophil accumulation at 24-48 h after OLT in a dose-dependent manner. Reduced hepatic injury with inhaled CO is associated with marked downregulation of early mRNA expression for TNF-alpha and IL-6. Expression in liver grafts of mRNA and protein of the stress-responding enzyme inducible nitric oxide synthase was significantly reduced by CO, while HO-1 was only marginally suppressed. Cold hepatic I/R injury was associated with prompt MAPK phosphorylation in liver grafts at 1 h after OLT, and CO significantly inhibited phosphorylation of ERK1/2 MAPK and its upstream MEK1/2 and downstream transcriptional factor c-Myc. CO also significantly inhibited I/R injury-induced STAT1 and STAT3 activation. In contrast, CO did not inhibit p38 or JNK MAPK pathways during hepatic I/R injury. Results demonstrate that exogenous CO suppresses early proinflammatory and stress-response gene expression and efficiently ameliorates hepatic I/R injury. The possible mechanism may include the downregulation of MEK/ERK1/2 signaling pathway with CO.
Kaizu
Takashi
T
Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Ikeda
Atsushi
A
Nakao
Atsunori
A
Tsung
Allan
A
Toyokawa
Hideyoshi
H
Ueki
Shinya
S
Geller
David A
DA
Murase
Noriko
N
D000280:Administration, Inhalation; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D002248:Carbon Monoxide / Q000008:administration & dosage*; D002263:Carboxyhemoglobin / Q000378:metabolism; D050377:Cold Ischemia / Q000009:adverse effects*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D016031:Liver Transplantation / Q000009:adverse effects*; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009336:Necrosis; D020556:Neutrophil Infiltration / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D020011:Protective Agents / Q000008:administration & dosage*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D015427:Reperfusion Injury / Q000201:enzymology / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D050791:STAT Transcription Factors / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D015850:Interleukin-6; D020011:Protective Agents; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D050791:STAT Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D006419:Heme Oxygenase (Decyclizing); C491523:Hmox1 protein, rat; D000410:Alanine Transaminase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020930:MAP Kinase Kinase Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2