Role of autophagy in lung injury in septic mice / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of autophagy in the lung injury in the septic mice.Methods Thirty-six male C57BL/6 mice, aged 6 weeks, weighing 20-25 g, were randomly divided into 3 groups (n=12 each) using a random number table sham operation group (group S);cecal ligation and puncture (CLP) group;CLP + autophagy inhibitor 3-methyladenine (3-MA) group (group CLP+3-MA).Sepsis was produced by CLP.In group CLP+3-MA, 3-MA 10 mg/kg was injected intraperitoneal at 1 h after operation.Arterial blood samples were taken at 24 h after operation for blood gas analysis, and the oxygenation index was calculated.The lungs were removed for microscopic examination of pathologic changes which were scored, and for determination of wet/dry lung weight ratio (W/D ratio) , myeloperoxidase (MPO) activity (using colorimetric method) and the expression of autophagy protein microtubule-associated protein 1 light chain 3 Ⅱ] (LC3 Ⅱ), Beclin-1 and lysosomes-associated protein Rab7 and lysosome-associated membrane protein-2 (LAMP2) (by Western blot).The lung was lavaged, and broncho-alveolar lavage fluid (BALF) was collected for determination of the total cell count and polymorphonuclear leukocyte (PMN) count.Results Compared with group S, the pathological score, W/D ratio, MPO activity, and the total cell and PMN counts in BALF were significantly increased, and oxygenation index was decreased in CLP and CLP +3-MA groups, and the expression of LC3 Ⅱ , Beclin-1, LAMP2 and Rab7 was up-regulated in group CLP (P＜0.05).Compared with group CLP, the pathological score, W/D ratio, MPO activity, and the total cell and PMN counts in BALF were significantly increased, the oxygenation index was decreased, and the expression of LC3 Ⅱ , Beclin-1, LAMP2 and Rab7 was down-regulated in group CLP+ 3-MA (P＜0.05).Conclusion Autophagy is involved in the endogenous protective mechanism of acute lung injury in the septic mice.