右美托咪定调节cGAS-STING信号通路对烧伤大鼠炎性损伤的影响

Effects of Dexmedetomidine on Inflammatory Injury in Burned Rats by Regulating the cGAS-STING Signaling Pathway

目的:探究右美托咪定(DEX)调节环鸟苷酸-腺苷酸合成酶(cGAS)-干扰素基因刺激蛋白(STING)信号通路对烧伤大鼠炎性损伤的影响。方法:将大鼠随机分为对照组(Control组)、模型组(Model组)、DEX低、中、高剂量组(DEX-L、DEX-M、DEX-H组),DEX-H+cGAS-STING信号通路激活剂组(DEX-H+DMXAA组),每组12只,除Control组外,利用过烫伤仪建立大鼠深Ⅱ度烧伤模型。DEX-L、DEX-M、DEX-H组给予1、3、5μg·kg^(-1)·h^(-1)DEX 4h。DEX-H+DMXAA组给予25mg/kg DMXAA和5μg·kg^(-1)·h^(-1)DEX,4h;Control组和Model组给予等量0.9%生理盐水4h,每天1次,连续2周。药物干预结束评估大鼠创面愈合情况,计算创面愈合率;ELISA法检测血清肿瘤坏死因子(TNF-α)、白细胞介素1β(IL-1β)水平;HE染色评估创面组织病理损伤,并进行损伤评分;TUNEL染色法评估创面组织细胞凋亡;qRT-PCR检测创面组织中cGAS、STING mRNA表达;Western blot检测凋亡相关蛋白(Bax、Bcl-2)及cGAS-STING通路蛋白表达。结果:与Control组比较,Model组TNF-α、IL-1β水平、创面组织细胞凋亡率、cGAS、STING mRNA及Bax、cGAS、STING、IRF3蛋白表达升高,Bcl-2表达降低(P<0.05);与Model组比较,DEX-L、DEX-M、DEX-H组创面愈合率、创面组织学评分、Bcl-2表达升高,TNF-α、IL-1β水平、创面组织细胞凋亡率、cGAS、STING mRNA及Bax、cGAS、STING、IRF3表达蛋白表达降低,且各剂量组间差异有统计学意义(P<0.05);与DEX-H组比较,DEX-H+DMXAA组创面愈合率、创面组织学评分、Bcl-2表达降低,TNF-α、IL-1β水平、创面组织细胞凋亡率、cGAS、STING mRNA及Bax、cGAS、STING、IRF3表达蛋白表达升高(P<0.05)。结论:DEX具有抑制炎症反应、减少细胞凋亡,促进创面愈合的作用,其机制可能与抑制cGAS-STING通路激活有关。

Objective:To investigate the effects of dexmedetomidine(DEX)on inflammatory injury in burned rats by regulating the cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING)signaling pathway.Methods:Rats were randomly divided into six groups:control group(Control),model group(Model),low dose,medium and high dose DEX groups(DEX-L,DEX-M,DEX-H),and DEX-H+cGAS-STING pathway activator group(DEX-H+DMXAA),with 12 rats in each group.Except for the Control group,all rats were subjected to deep second-degree burns using a burn injury device.The DEX-L,DEX-M,and DEX-H groups received 1,3,and 5μg·kg^(-1)·h^(-1)DEX for 4 hours,respectively.The DEX-H+DMXAA group was administered 25 mg/kg DMXAA and 5μg·kg^(-1)·h^(-1)DEX for 4 hours.The Control and Model groups received equivalent amounts of 0.9%saline for 4 hours daily for two weeks.After the intervention,wound healing rates were calculated,serum levels of tumor necrosis factor(TNF-α)and interleukin-1β(IL-1β)were detected by ELISA,and histopathological injury scores were assessed by HE staining.Apoptosis in wound tissues was evaluated by TUNEL staining.The expression of cGAS and STING mRNA in wound tissues was measured by qRT-PCR,while apoptosis-related proteins(Bax,Bcl-2)and cGAS-STING pathway proteins were detected by Western blot.Results:Compared with the Control group,the Model group showed significantly higher levels of TNF-α,IL-1β,wound tissue apoptosis rate,cGAS,STING mRNA,and Bax,cGAS,STING,IRF3 protein expression,while Bcl-2 expression decreased(P<0.05).Compared with the Model group,the DEX-L,DEX-M,and DEX-H groups had significantly increased wound healing rates,higher histopathological scores,elevated Bcl-2 expression,and reduced TNF-α,IL-1βlevels,wound tissue apoptosis rate,cGAS,STING mRNA,and Bax,cGAS,STING,and IRF3 protein expression,with statistically significant differences between the dosage groups(P<0.05).In the DEX-H+DMXAA group,wound healing rates,histopathological scores,and Bcl-2 expression were lower,while TNF-α,IL-1βlevels,wound tissue apoptosis rate,cGAS,STING mRNA,and Bax,cGAS,STING,and IRF3 protein expression were higher compared with the DEX-H group(P<0.05).Conclusion:DEX has anti-inflammatory effects,reduces cell apoptosis,and promotes wound healing in burned rats,and its mechanism may be related to inhibiting the activation of the cGAS-STING signaling pathway.