增加受者体内一氧化碳含量在减轻小鼠移植心缺血再灌注损伤中的作用和机制

目的 观察心脏移植前用二氯甲烷(MC)灌胃增加受者体内一氧化碳含量在减轻小鼠移植心缺血再灌注损伤中的作用及其机制.方法 以Balb/c小鼠作为供、受者,建立颈部异位心脏移植模型.实验共分为4组,分别为MC 100 mg组(n=10)、MC 500 mg组(n=12)、橄榄油组(n=10)和正常对照组(n=5).前3组在麻醉前3 h分别用经橄榄油稀释的MC 100 nag/kg、MC 500mg/kg及单纯橄榄油0.15 ml对受者进行灌胃处理,然后行颈部异位心脏移植;正常对照组小鼠仅作麻醉处理,不进行心脏移植.分别于灌胃后0、1、3、6、12和24 h剪尾采血,测定血液中CO的含量用碳氧血红蛋白(COHb)占总血红蛋白的百分比表示],并于相应时间点取心肌组织,检测心肌组织中CO的含量;各组移植后3和24 h分别处死半数受者,检测移植后3和24 h血清中肌钙蛋白I(cT-nI)、心肌组织中肿瘤坏死因子α(TNF-α)、白细胞介素10(IL-10)、细胞凋亡与相关基因Bcl-2和Bax mRNA以及核因子κB(NF-κB)的表达,并观察移植心心肌的超微结构.结果 与橄榄油组比较,MC 100 mg和MC 500 mg组受者血液中COHb浓度与心肌组织中CO含量明显升高,均在灌胃后3h达到峰值;MC 100 mg组和MC 500mg组受者心脏移植后3和24h,能显著降低血清中cTnI水平(P<0.01),并以MC 500 mg组降低最为明显;可明显下调促炎症基因TNF-α mRNA水平(P<0.01),而抗炎症基因IL-10 mRNA上调不明显(P>0.05),同时可以显著上调抗凋亡基因Bcl-2 mRNA水平(P<0.01),并抑制促凋亡基因Bax mRNA的转录(P<0.01);心肌超微结构损伤明显减轻.正常对照组可见少量NF-κB表达,而橄榄油组、MC 100 mg组和MC 500 mg组NF-κB活性均显著增强(P<0.01),但后三组之间NF-κB活性的差异无统计学意义(P>0.05).结论 诱导受者体内增加CO含量能通过其抗炎症和抗凋亡功能而减轻移植心缺血再灌注损伤;但与抑制NF-κB信号转导通路无关.

The increase of carbon monoxide in recipients ameliorates isehemia/reperfusio.injury in a murine heart transplantation model

Objective To examine whether the increase of carbon monoxide (CO) induced by oral methylene chloride (MC) administration in recipients before heart transplantation would protect heart grafts against isehemia/reperfusion (I/R) injury associated with transplantation and to explore the possible mechanism.Methods Inbred male Balb/c mice were used as donors and recipients to establish cervical heart transplantation model Recipients were treated with either MC (100 mg/kg or 500 mg/kg,per os)(group MC 100 mg,n=10;group MC 500 mg,n=12) or olive oil(0.15 ml,per os.group olive,n=10) 3 h prior to anesthesia.Age-matched norwlal mice served as controls (group N,n=5).The serum COHb and the CO content of myocardial tissue were measured at 0,1,3,6,12,24 h after oral MC administration.Half of recipients were killed at 3 and 24h after transplantation for senum or cardiac graft samples.The serum cTnI levels,the mRNA levels of TNF-α,IL-10,Bcl-2,Bax.the protein levels of NF-κB and the ultrastructures of myocardium were examined.Results As tompared with group olive.the serum COHb and tissue CO were increased significantly and peaked within 3 h in group MC 100 mg and group MC 500 mg.The serum cTnI levels in group MC 100 mg and group MC 500 mg were significantly decreased (P<0. 01 ), especially in group MC 500 mg. The increase of CO in recipients of group MC100 mg and group MC 500 mg significantly inhibited the proinflammatory gene expression of TNF-α mRNA and the pro-apoptotic gene expression of Bax mRNA (P<0. 01), and increased the anti-apoptotic gene expression of Bcl-2 mRNA (P<0. 01), but did not increase the anti-inflammatory gene expression of IL-10 mRNA (P>0. 05) in the heart grafts. As compared with group N, the myocardial NF-κB activation was increased significantly in group olive,group MC 100 mg and group MC 500 mg (P<0. 01 ), but there was no significant difference among the later three groups (P>0. 05). The myocardial ultrastructure was also alleviated significantly in group MC 100 mg and group MC 500 mg as compared with group N. Conclusion The increase of CO induced by MC in recipients suppresses pro-inflammatory and pro-apoptotic gene expression and efficiently ameliorates transplant-induced heart I/R injury. The possible mechanism does not seem to be associated with down-regulation of the NF-κB signaling pathway.