Effect and mechanism of exogenous carbon monoxide against excessive neutrophil infiltration in liver and lung tissues during sepsis / 中华创伤杂志

ABSTRACT

Objective To determine the inhibitory effect and mechanism of exogenous carbon monoxide against excessive neutrophil infiltration in liver and lung tissues during sepsis.Methods Thirty-two mice were subjected to sham operation (sham group),cecal ligation and perforation (CLP) group,CLP with 8 mg/kg of exogenous carbon monoxide releasing molecule Ⅱ (CORM-2) (CORM-2 group),and CLP with 8 mg/kg of inactive variants of CORM-2 (iCORM-2) (iCORM-2 group) according to the random number table,with 8 mice per group.Liver and lung tissues were collected at 24 hours after surgery to examine the pathologic changes,myeloperoxidase (MPO) activity and malonaldehyde (MDA) content.Another 60 mice were enrolled into the same 4 groups with 15 mice per group and were tested for 72-hour survival rate.Bone marrow neutrophils were isolated and divided into normal control group,1 μg/ml lipopolysaccharide (LPS) group,1 μg/ml LPS plus 10 μmol/L CORM-2 group (low dose group),1 μg/ml LPS plus 50 μmol/L CORM-2 group (high dose group),1 μg/ml LPS plus 50 μmol/L iCORM-2 group (iCORM-2 group).Under the agarose chemotaxis,qPCR and immunofluorescence detection of formyl peptide receptor 1 (FPR1) were performed.Results CLP group presented enhanced activity of MPO [liver(9.1 ± 1.1) U/g,lung(16.3 ± 2.8) U/g],increased MDA content [liver(76.5 ±11.3) nmol/mg,lung(32.4 ± 10.3) nmol/mg] and 72-hour survival rate of 20％ as compared with the sham group (all P ＜ 0.05).CORM-2 group showed inhibited activity of MPO [liver(5.2 ± 0.8) U/g,lung(7.5 ± 2.4) U/g],increased MDA content [liver(46.7 ± 6.1) nmol/mg,lung(23.8 ±7.3) nmol/mg] and 72-hour survival rate of 67％ as compared with the sham group (all P ＜ 0.05).LPS enhanced neutrophil migration (61.3 ± 7.1) (P ＜ 0.05) and expression of FPR1 which was enriched in the membrane.Meanwhile,neutrophil migration was significantly inhibited in a dose-dependent of CORM-2 (low dose group43.3 ±6.1,high-dose group23.3 ±5.9) (P＜0.05).Conclusions Exogenous carbon monoxide is effective to inhibit the excessive neutrophil infiltration,attenuate oxidative stress or pathological injury,and improve the survival from sepsis.The mechanism is associated with the down-regulation of FPR1,inhibition of FPR1 enrichment in the membrane,and decreased neutrophil migration.