[The therapeutic effect of carnosine combined with dexamethasone in the lung injury of seawater-drowning]

Objective: To explore the therapeutic effect of carnosine and dexamethasone in lung injury caused by seawater drowning. Methods: The in vitro experiments with A549 cells were divided into 5 groups: blank control group (C), seawater injury group (S), seawater injury+dexamethasone treatment group (S+D), seawater injury+carnosine treatment group (S+C), seawater injury dexamethasone and carnosine combined therapy(S+D+C) group. The optimal therapeutic dose of drugs for the treatment of seawater drowning lung injury was tested in vitro. Based on the optimal dose, the levels of TNF-α and IL-6 in each group at different time points were detected at the cell level by ELISA. The level of apoptosis was detected by flow cytometry. The in vivo experiments with SD rats were randomly divided into 5 groups (n=8 each): blank control group (RC),seawater drowning injury group (RS),seawater drowning injury+dexamethasone treatment group (RSD),seawater drowning injury+carnosine treatment group (RSC),seawater drowning injury+dexamethasone+carnosine combined treatment group (RSDC). The animal model with seawater inhalation acute lung injury was made by intratracheal infusion (4 ml/kg). The pathological changes of the lungs were observed. The expression of superoxide dismutase (SOD) in each group was detected by Western blot. Results: The results of in vitro experiments showed significant increase of apoptosis after seawater injury. The normal cell rate in group C was 98.3% while the apoptosis rate was 1.7%. The normal cell in group S was 18.8%, and the apoptosis rate was 81% (P<0.01). TNF-α and IL-6 levels in group S increased to 180.25 ng/L and 61.56 ng/L, respectively, which were statistically significant compared with group C (P<0.01). After drug protection, apoptosis was reduced in S+D group, S+C group and S+D+C group, with apoptosis rates of 65.4%, 70.9% and 42.6%, respectively. The contents of TNF-α and IL-6 also decreased in the S+D+C group (P<0.01). The results of in vivo experiments showed obvious lung injury and disordered lung tissue structures in the RS group at 4 h after modeling. There was hemorrhage in the pulmonary interstitium and a large number of inflammatory cells. Results of western blot showed that the expression of SOD increased in the RS group. Compared with RS group, the treatment alleviated acute lung injury and decreased the expression level of SOD in RSD, RSC and RSDC groups (P<0.01). Conclusion: Dexamethasone and carnosine reduced the influence of seawater inhalation on the lung in the rat model. The positive effect of combination of these two drugs on lung injury caused by seawater inhalation was stronger than a single drug.

目的： 探究肌肽和地塞米松在海水淹溺性肺损伤中的联合治疗作用。 方法： （1）体外实验：将A549细胞分为空白对照组（C）、海水损伤组（S）、海水损伤+地塞米松治疗组（S+D）、海水损伤+肌肽治疗组（S+C）、海水损伤+地塞米松+肌肽联合治疗组（S+D+C）。体外检测单药及两药联合治疗海水淹溺性肺损伤的最佳治疗剂量。（2）基于最佳剂量，在细胞水平上利用ELISA法检测不同时间点各组中肿瘤坏死因子（TNF-α）及IL-6的水平，利用流式细胞仪检测各组细胞凋亡水平。（3）体内实验：将40只雄性SD大鼠按照完全随机方法分为5组，大鼠空白对照组（RC）、大鼠海水损伤组（RS）、大鼠海水损伤+地塞米松治疗组（RSD）、大鼠海水损伤+肌肽治疗组（RSC）、大鼠海水损伤+地塞米松+肌肽联合治疗组（RSDC），每组8只。采用气管内滴注（4 ml/kg）的方法制作海水吸入型急性肺损伤大鼠模型，观察肺部病理变化，Western blot法检测各组中超氧化物歧化酶（SOD）的表达情况。 结果： 体外实验结果显示海水损伤后细胞凋亡明显增加，C组正常细胞为98.3%，细胞凋亡率为1.7%；S组正常细胞为18.8%，细胞凋亡率为81%，损伤具有统计学意义（P<0.01）；S组TNF-α、IL-6水平上升，分别为180.25和61.56 ng/L，与C组比较具有统计学意义，且P<0.01。给予药物保护后，S+D组、S+C组及S+D+C组细胞凋亡减少，细胞凋亡率分别为65.4%、70.9%、42.6%；TNF-α及IL-6的含量也明显降低，且S+D+C组效果最明显（P<0.01）。体内实验结果显示海水吸入4 h后，大鼠肺部损伤明显，RS组肺组织结构紊乱，肺间质可见出血并可见大量炎症细胞浸润；Western blot结果显示RS组超氧化物歧化酶（Superoxide Dismutase，SOD）表达量增高。给予药物预处理后，RSD组、RSC组、RSDC组海水吸入导致的急性肺损伤情况较RS组好转，SOD表达量减低（P<0.01）。 结论： 在海水淹溺性肺损伤大鼠模型中地塞米松及肌肽能够减轻海水吸入导致的肺损伤，且两药联合对海水吸入肺损伤的保护作用强于单药保护作用。.

Keywords: Carnosine; Dexamethasone.; Near drowning; Respiratory distress syndrome, adult; Sea water.