Effect of activating cannabinoid receptor 2 on sepsis-induced acute lung injury in mice: the role of autophagy / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of activating cannabinoid receptor 2 (CB2R) on sepsis-induced acute lung injury and the role of autophagy in mice.Methods Twenty-four SPF male C57BL/6 mice,aged 8-10 weeks,weighing 20-25 g,were divided into 4 groups (n=6 each) using a random number table method:sham operation group (group Sham),sepsis group (group Sep),sepsis plus CB2R agonist HU308 group (group Sep+HU308) and sepsis plus HU308 plus autophagy inhibitor 3-methyladenine group (group Sep+HU308+3-MA).Sepsis was induced by cecal ligation and puncture in anesthetized mice.HU308 2.5 mg/kg was intraperitoneally injected at 15 min after surgery in Sep+HU308 and Sep+ HU308+3-MA groups,and 15 min later 3-MA 10 mg/kg was intraperitoneally injected in group Sep+ HU308+3-MA.Lung tissues were obtained at 12 h after surgery and stained with haematoxylin and eosin for examination of the pathological changes which were scored and for determination of the expression of tumornecrosis factor-alpha (TNF-α),interleukin-18 (IL-18) and IL-1β mRNA (by real-time polymerase chain reaction),expression of autophagy-related protein 5 (Atg5) (by immuno-histochemistry),and expression of microtubule-associated protein 1 light chain 3 (LC3),Beclin-1 and p62 (by Western blot).The ratio of LC3Ⅱ to LC3Ⅰ (LC3Ⅱ/LC3Ⅰ ratio) was calculated.Results Compared with group Sham,the expression of TNF-α,IL-18 and IL-1β mRNA was significantly up-regulated,and LC3 Ⅱ/LC3 Ⅰ ratio and lung injury score were increased in the other three groups,the expression of Beclin-1 was up-regulated,and the expression of p62 was down-regulated in group Sep and group Sep+HU308,and the expression of p62 was significantly up-regulated in group Sep+HU308+3-MA (P＜0.05).Compared with group Sep,the expression of TNF-α,IL-18 and IL-1β mRNA was significantly down-regulated,the expression of Atg5 was up-regulated,and lung injury score was decreased in group Sep+ HU308 and group Sep+ HU308 + 3-MA,LC3Ⅱ/LC3Ⅰ ratio was increased,the expression of Beclin-1 was up-regulated,and the expression of p62 was down-regulated in group Sep+HU308,and the expression of Beclin-1 was down-regulated,and the expression of p62 was up-regulated in group Sep + HU308 + 3-MA (P ＜ 0.05).Compared with group Sep+ HU308,the expression of TNF-α,IL-18 and IL-1β mRNA was significantly up-regulated,the expression of Atg5 and Beclin-1 was down-regulated,LC3Ⅱ/LC3Ⅰ ratio was decreased,the expression of p62 was up-regulated,and lung injury scores were increased in group Sep+HU308+3-MA (P＜0.05).Conclusion Activating CB2R can alleviate acute lung injury in septic mice,and the mechanism may be partially related to enhancing autophagy and reducing inflammatory responses.