地塞米松联合谷氨酰胺减轻急性肺损伤大鼠肺组织炎症和肺水肿的机制

Mechanism of dexamethasone combined with glutamine in reducing lung inflammation and pulmonary edema in rats with acute lung injury

目的探讨地塞米松(DEX)联合谷氨酰胺(Gln)对脂多糖(LPS)诱导的急性肺损伤大鼠肺组织炎症和肺水肿的影响及相关机制。方法50只Wistar大鼠随机分为对照组、模型组、地塞米松组(DEX)和DEX联合Gln组。除对照组外,其余大鼠采用6 mg/kg LPS腹腔注射诱导急性肺损伤。实时荧光定量PCR检测肺组织p38丝裂原激活蛋白激酶(p38 MAPK)、含pyrin结构域核苷酸结合寡聚结构域样受体家族蛋白3(NLRP3)、核因子κB(NF-κB)的mRNA表达,Western blot法检测肺组织磷酸化的p38 MAPK(p-p38 MAPK)、NLRP3、磷酸化的核因子κB抑制蛋白(p-IκB)、NF-κB p65、水通道蛋白1(AQP1)、AQP5蛋白的表达,ELISA检测血清肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、IL-1β含量,分光光度计检测肺组织超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)含量。结果与对照组比较,模型组大鼠肺指数降低,血清TNF-α、IL-6、IL-1β含量显著升高,肺组织p38 MAPK、NLRP3、NF-κB mRNA和p-p38 MAPK、NLRP3、p-IκB、NF-κB p65蛋白相对表达显著升高,AQP1、AQP5蛋白相对表达降低,肺组织SOD、GSH-Px含量降低,MDA含量升高;与模型组比较,各治疗组上述症状和指标均显著改善,其中以DEX联合Gln组最为显著。结论DEX联合Gln通过抑制炎症反应,抗氧化损伤,减轻肺水肿,防治急性肺损伤,其机制与抑制p38 MAPK、NLRP3、NF-κB信号通路活化,促进AQP1、AQP5表达,以及促进抗氧化产物的活性相关。

Objective To investigate the effect of dexamethasone(DEX)combined with glutamine(Gln)on lung inflammation and pulmonary edema in rats with acute lung injury induced by lipopolysaccharide(LPS)and its related mechanisms.Methods Fifty Wistar rats were randomly divided into control group,model group,dexamethasone group(DEX)and DEX combined with Gln group.Except for the control group,rats in other groups were injected with 6 mg/kg LPS intraperitoneally to induce an acute lung injury.The mRNA expression of p38 MAPK,NLRP3,and NF-κB in lung tissue were detected by real-time quantitative PCR.The protein expressions of p-p38 MAPK,NLRP3,phosphorylated inhibitor of nuclear factorκB(p-IκB),NF-κB p65,aquaporin 1(AQP1)and AQP5 in lung tissue were detected by Western blot analysis.ELISA was used to detect the content of serum tumor necrosis factor-α(TNF-α),interleukin 6(IL-6),interleukin 1β(IL-1β).Spectrophotometer was employed to detect the content of superoxide dismutase(SOD),malondialdehyde(MDA)and glutathione peroxidase(GSH-Px)in lung tissue.Results Compared with the control group,the lung index of the model group decreased,the content of the serum inflammatory factors TNF-α,IL-6 and IL-1βsignificantly increased,and the protein expression of p38 MAPK,NLRP3,NF-κB mRNA,p-p38 MAPK,NLRP3,p-IκB and NF-κB p65 in the lung tissue significantly increased,while that of AQP1,AQP5 decreased,and the content of SOD and GSH-Px in lung tissue decreased,while that of MDA increased;Compared with the model group,the above mentioned symptoms and indicators in each treatment group were significantly improved,among which the DEX combined with Gln group was the most significant.Conclusion DEX combined with Gln can inhibit inflammation,resist oxidative damage,relieve pulmonary edema,and prevent acute lung injury.Its mechanism is related to inhibiting the activation of p38 MAPK,NLRP3,and NF-κB signaling pathways,promoting the expression of AQP1 and AQP5,and promoting the activity of antioxidant products.