多西环素对大鼠体外循环后肺内MMP-9和TIMP活性和基因表达的影响

目的:探讨多西环素对大鼠体外循环后肺内基质金属蛋白酶-9(MMP-9)和组织基质金属蛋白酶抑制剂-1(TIMP-1)活性和基因表达的影响?方法:健康雄性SD大鼠36只随机分为对照组?体外循环组(CPB组)和治疗组,分别于手术结束时(T1)和手术结束后6 h(T2)收集支气管肺泡灌洗液(BALF)和肺组织标本?Western blot法测定BALF中MMP-9和TIMP-1的蛋白活性,RT-PCR法测定肺组织MMP-9和TIMP-1 mRNA的表达?结果:治疗组大鼠肺组织水肿减轻,BALF的中性粒细胞减少;CPB组BALF中MMP-9活性明显升高,CPB后6 h表达最强,治疗组MMP-9活性较CPB组有明显下降,TIMP-1的活性在CPB组和治疗组于CPB结束后呈较弱的增强趋势,两组间相同时间点的表达差异不明显;CPB组和治疗组MMP-9mRNA表达增强,但治疗组MMP-9 mRNA的表达在相应时间点较治疗组下降;TIMP-1 mRNA在治疗组表达增强,且T2时间点显著增强;MMP-9/TIMP-1 mRNA在CPB组和治疗组均有显著增大,但治疗组中T2时间点MMP-9/TIMP-1 mRNA比值较CPB组明显下降?结论:CPB可以引起大鼠术后肺内MMP-9的活性和基因表达增强,导致术后早期肺内MMP-9/TIMP-1 mRNA表达失衡,多西环素可以抑制CPB后大鼠肺组织内MMP-9蛋白水平和mRNA的表达,还可能上调TIMP-1的表达而间接抑制MMP-9 mRNA表达,改善MMP-9/TIMP-1的比例失衡?

Effects of doxycycline on MMP-9 and TIMP-1 activity and mRNA expression in lung after cardiopulmonary bypass in rats

Objective:This study was aimed to investigate the effects of doxycycline on the activity and mRNA expression of MMP-9 and TIMP-1 in CPB in a rat model. Methods:Male Sprague-Dawley rats were randomly divided into 3 groups (n = 12,respectively):the sham group,the CPB group,and the CPB+Dox group. The rats were executed at the termination of CPB (T1),6h after termination of CPB(T2),respectively. BALF and lung tissues were harvested at T1 and T2. The activity of MMP-9 and TIMP-1 was detected by Western-blot analysis. The expression of MMP-9 and TIMP-1 in lung tissue was detected by RT-PCR. Results:The edema of lung tissue was significantly reduced in the CPB+Dox group,and neutrophils were decreased in the CPB group. The activity of MMP-9 in the CPB+Dox group decreased significantly compared with that in the CPB group and the highest expression occured after 6 h. The activity of TIMP-1 had a weaker increasing trend in the CPB and the CPB+Dox group after the ending of CPB,and the expression difference was not obvious in the response time of the two groups. The expression of MMP-9 mRNA was significantly increased after CPB in the CPB and the CPB+Dox group,but significantly decreased at T2 time point in the CPB+Dox group. The ratio of MMP-9/TIMP-1 was significantly increased in the CPB and CPB+Dox group,but the ratio in CPB+Dox group was significantly lower than that of CPB group at T2 time. Conclusion:CPB could induce the increasing of the activity and mRNA of MMP-9 of lung,causing the ratio of MMP-9/TIMP-1 imbalanced severely at the early postoperative. Doxycycline could inhibit the expression of MMP-9 activity and mRNA in rat lung tissue after CPB,and may increase the expression of TIMP-1 in rats after CPB,and inhibit the expression of MMP-9 mRNA indirectly,which could improve the ratio of MMP-9/TIMP-1 imbalance.