cGAS-STING信号通路在疾病中的作用

环GMP-AMP合成酶(cyclic GMP-AMP synthase,cGAS)是一种新发现的DNA感受器.近年来,越来越多的研究表明它介导的干扰素基因刺激因子(stimulator of interferon genes,cGAS-STING)信号通路参与了多种疾病的发生与发展.深入了解cGAS-STING信号通路...     

cGAS-STING信号通路在急性心肌梗死小鼠模型中表达及作用

[目的]探究环磷酸鸟苷-腺苷酸合成酶/干扰素刺激基因(cGAS-STING)信号通路在急性心肌梗死(AMI)小鼠模型中表达及作用。[方法]选择10～12周龄C57野生型小鼠,分为假手术组(只穿线不结扎)、模型组(结扎冠脉左降前支建立AMI小鼠模型)、STING抑制组(建模+腹腔注射5 mg/kg STING抑制剂C18)各10只,采用超声评估其心功能,HE染色、TUNEL法评估心肌组织病理情况及细胞凋亡,ELISA法检测血清炎性因子表达,Western Blot检测心肌组织cGAS、STING、IRF3及p-IRF3蛋白表达。[结果]与假手术组比较,模型组LVESD、LVEDD、心脏重量、左心室重量及其重量指数、心肌细胞凋亡率、血清TGF-β、IL-6、IL-18水平、心肌组织cGAS、STING、p-IRF3/IRF3蛋白表达明显升高,心脏梗死面积扩大,LVFS、LVEF下降;与模型组比较,STING抑制组LVEF、LVFS升高,LVESD、LVEDD、心脏重量、左心室重量及其重量指数、心肌细胞凋亡率、血清TGF-β、IL-6、IL-18水平、心肌组织cGAS(1.99±0.12 vs 0.73±0.09)、STING(1.41±0.18 vs 0.37±0.12)、p-IRF3/IRF3蛋白表达降低,梗死面积减少(P<0.05)。[结论]阻断cGAS-STING信号通路能改善AMI小鼠心功能,其机制可能与能减少心肌细胞凋亡和心室重构有关。     

cGAS-STING信号通路在肿瘤免疫治疗中的作用

环鸟苷酸-腺苷酸合成酶(cyclic GMP-AMP synthase,cGAS)-干扰素基因刺激因子(stimulator of interferon genes,STING)信号通路作为先天免疫的重要组成部分,在抗肿瘤免疫中发挥着关键作用。cGAS通过识别细胞自身异常或外源的DNA,催化合成第二信使cGAMP,激活STING蛋白,进而通过TBK1-IRF3/NF-κB信号轴诱导I型干扰素等细胞因子分泌。这些效应可激活树突状细胞、增强自然杀伤细胞功能和T细胞应答,进而强化机体的免疫监视功能,从而抑制肿瘤进展。然而,肿瘤细胞可通过多种机制逃逸该通路的免疫监控,包括下调cGAS/STING表达,加速STING蛋白降解或抑制cGAMP合成及信号传递等,导致免疫抑制性微环境形成,促进肿瘤免疫逃逸。目前,靶向激活cGAS-STING通路的策略主要包括STING激动剂开发、递送系统优化及联合治疗,例如与PD-1/PD-L1抑制剂、与放疗或化疗等联用,以协同增强抗肿瘤免疫应答。尽管前景广阔,但该领域仍面临挑战,例如STING激动剂的全身毒性、肿瘤微环境异质性及耐药机制等。本文系统综述了cGAS-STING信号通路活化的分子机制和在肿瘤免疫中的作用、STING激动剂和递送系统的进展及存在问题,及其与免疫检查点抑制剂、放疗和化疗等联合应用潜力,提出cGAS-STING通路作为治疗靶点面临的挑战及未来可能优化方向,为开发更有效的肿瘤免疫治疗策略提供理论依据和思路。     

新型胞质DNA感受通路：cGAS-STING的研究进展

细胞胞质中存在的游离DNA一直被宿主的固有免疫系统当做潜在的危险信号,但免疫系统识别和清除这些危险信号的机制还不明确.近几年有研究发现,DNA感受器(DNA sensor)是宿主感受DNA和免疫防御的桥梁,目前已经有超过10种DNA感受器被发现,而干扰素刺激基因(stimulator of interferon genes,STING,也称为TMEM173、MPYS、MITA和ERIS)作为一种DNA感受通路下游关键的接头分子,在感受胞质DNA和免疫防御方面起着重要的信号传递作用,胞质中的DNA可通过DNA感受器激活STING,再激活Ⅰ型干扰素和其他细胞因子,进而启动机体的免疫反应.近些年,胞质中游离DNA如何激活STING,进而如何在体内启动免疫反应以产生抗病毒或抗菌作用的机制研究取得了显著进展.最近,在哺乳动物细胞中发现了一种新型的核酸转移酶cGAS(cyclic GMP-AMPsynthase),它能识别DNA并能产生一种内源性的环化二核苷酸cGAMP(cyclic GMP-AMP)激活STING.本文将最近关于cGAS的发现、胞质DNA通过cGAS激活STING及STING活化后激活机体免疫反应的机制进行了综述.     

STING信号通路的研究进展

干扰素基因刺激因子(Stimulator of interferon gene, STING)作为固有免疫系统的关键性接头蛋白,在外源或内源DNA介导的免疫应答中发挥重要作用,广泛参与宿主体内的多种信号传导过程。概述了STING信号通路分子机制及其在抗病毒感染、自身免疫疾病、神经系统疾病和肿瘤中的作用,介绍了常见的STING激动剂和抑制剂,以期为STING的进一步研究提供参考。     

内源性一氧化氮在高血压心肌肥厚中的作用

目的和方法：本实验用Ｌ精氨酸和一氧化氮合酶（ＮＯＳ）抑制剂ＬＮＡＭＥ观察内源性一氧化氮（ＮＯ）在高血压性心肌肥厚中的作用。结果：腹主动脉缩窄引起大鼠动脉血压显著升高,左心室重量／体重比值显著增加,左心室ＮＯ含量显著下降;Ｌ精氨酸不影响主动脉缩窄大鼠动脉血压,但减轻左心室重量／体重比值,明显升高左心室ＮＯ含量,加入ＬＮＡＭＥ可消除Ｌ精氨酸的上述作用;主动脉缩窄大鼠给予ＬＮＡＭＥ,动脉血压和左心室／体重比值并没有进一步增加;假手术大鼠给予ＬＮＡＭＥ,血压明显升高,左心室重量／体重比值轻度增加;主动脉缩窄大鼠不论是服用Ｌ精氨酸还是ＬＮＡＭＥ,左心室ｃＧＭＰ含量都明显增加。结论：口服Ｌ精氨酸可减轻主动脉缩窄大鼠心肌肥厚但不影响动脉血压,此作用可能是通过Ｌ精氨酸ＮＯ途径实现的,与ｃＧＭＰ机制无关。     

c-di-AMP在细菌感染与免疫中的作用

环二腺苷酸(Cyclic diadenosine monophosphate,c-di-AMP)是细菌中广泛存在的第二信号分子。c-di-AMP在细菌中的代谢受二腺苷酸环化酶(Diadenylatecyclase, DAC)和磷酸二酯酶(Phosphodiesterase,PDE)的精密调控。c-di-AMP不仅调节细菌生长、细胞壁稳态、离子转运等多种生理过程,而且能够被真核宿主胞内多种感应子/受体蛋白识别,从而调控抗感染免疫。细菌c-di-AMP参与调控宿主I型干扰素应答、NF-κB信号通路活性、自噬以及炎症小体应答等固有免疫应答。此外,c-di-AMP作为黏膜佐剂可诱导宿主适应性免疫。c-di-AMP被认为是一种新发现的病原体相关的分子模式(Pathogen associated molecular pattern,PAMP),已成为细菌疫苗和药物研究中的新靶点。     

β3 肾上腺素受体在心脏活动调节中的作用

1996年首次发现在人类心室肌组织中存在β3肾上腺素受体（β3-adrenoceptor,β3AR）,可以介导负性变力作用。该受体的结构与功能特性明显不同于β1AR和β2AR,这可能有助于深入了解病理情况下,心脏对儿茶酚胺的异常反应规律。心房中也存在β3AR,其作用尚无定论。心室β3AR主要通过抑制型G蛋白（Gi）-内皮型一氧化氮合酶（eNOS）-一氧化氮（NO）-环-磷酸鸟苷（cGMP）-Ca^2＋通路介导负性变力作用。心衰时,β3AR表达上调,与其偶联的Gi也上调,由于该受体不易脱敏并易被高浓度儿茶酚胺激活,因此该受体介导的负性变力作用可能参与心衰的病理生理机制。     

cGAS-STING信号通路在心血管疾病中的作用

环鸟苷酸腺苷酸合成酶(cyclic GMP-AMP synthase,cGAS)作为一种DNA感受器通过识别胞质DNA产生环鸟苷酸-腺苷酸(cyclic GMP-AMP,cGAMP)并激活干扰素基因刺激因子(stimulator of interferon gene,STING)及一系列下游通路从而介导免疫及炎症反应。近年来研究发现,cGAS-STING所介导的信号通路在心肌梗死、心力衰竭、心肌炎等多种心血管疾病中被显著激活,提示其在心血管系统疾病的发病进程中扮演重要角色。为了更深入了解cGAS-STING信号通路在心血管疾病中的作用,该文就cGAS的生化特点、cGAS-STING介导的信号通路及其在心血管疾病中的作用等方面的研究进展进行综述。     

The role of bacterial biofilms in ocular infections

There is increasing evidence that bacterial biofilms play a role in a variety of ocular infections. Bacterial growth is characterized as a biofilm when bacteria attach to a surface and/or to each other. This is distinguished from a planktonic or free-living mode of bacterial growth where these interactions are not present. Biofilm formation is a genetically controlled process in the life cycle of bacteria resulting in numerous changes in the cellular physiology of the organism, often including increased antibiotic resistance compared to growth under planktonic conditions. The presence of bacterial biofilms has been demonstrated on many medical devices including intravenous catheters, as well as materials relevant to the eye such as contact lenses, scleral buckles, suture material, and intraocular lenses. Many ocular infections often occur when such prosthetic devices come in contact with or are implanted in the eye. For instance, 56% of corneal ulcers in the United States are associated with contact lens wear. Bacterial biofilms may participate in ocular infections by allowing bacteria to persist on abiotic surfaces that come in contact with, or are implanted in the eye, and by direct biofilm formation on the biotic surfaces of the eye. An understanding of the role of bacterial biofilm formation in ocular infections may aid in the development of future antimicrobial strategies in ophthalmology. We review the current literature and concepts relating to biofilm formation and infections of the eye.     

The role of l-arginine-nitric oxide pathway in bacterial translocation

This study investigated the nitric oxide (NO) role as a mediator of arginine on bacterial translocation (BT) and gut damage in mice after intestinal obstruction (IO). The effects of pretreatment with arginine with or without NO inhibition on the systemic and local immunological response were also assessed. Mice were categorized into four groups. Group ARG received chow containing 2 % arginine, while group ARG + l-NAME received the same diet plus l-NAME (N-nitro-l-arginine methyl ester) by gavage. The IO and Sham groups were fed standard chow. After 7 days, animals were gavaged with radiolabeled Escherichia coli, anesthetized and subjected to IO, except the Sham group. Animals were euthanized after 18 h, and BT was evaluated in the mesenteric lymph nodes, blood, liver, spleen and lungs. In another experiment, the intestinal injury was assessed regarding intestinal permeability and ileum histological analyses. Intestinal secretory immunoglobulin A (sIgA) levels, serum IFN-γ and IL-10 cytokines were assessed. Arginine reduced BT, but NO inhibition enhanced BT compared with the ARG group (p < 0.05). Intestinal permeability in the ARG and ARG + l-NAME groups was similar but decreased when compared with the IO group (p < 0.05). Histological preservation was observed. Arginine treatment increased IL-10 and sIgA levels when compared with the Sham and IO groups (p < 0.05). The cytokines and sIgA concentrations were similar in the ARG + l-NAME and Sham groups. Arginine appeared to reduce BT and its effects on the modulation of cytokines and secretory IgA in mice after IO are mediated by NO production.     

Cutting edge: the toll pathway is required for resistance to gram-positive bacterial infections in Drosophila

In Drosophila, the response against various microorganisms involves different recognition and signaling pathways, as well as distinct antimicrobial effectors. On the one hand, the immune deficiency pathway regulates the expression of antimicrobial peptides that are active against Gram-negative bacteria. On the other hand, the Toll pathway is involved in the defense against filamentous fungi and controls the expression of antifungal peptide genes. The gene coding for the only known peptide with high activity against Gram-positive bacteria, Defensin, is regulated by both pathways. So far, survival experiments to Gram-positive bacteria have been performed with Micrococcus luteus and have failed to reveal the involvement of one or the other pathway in host defense against such infections. In this study, we report that the Toll pathway, but not that of immune deficiency, is required for resistance to other Gram-positive bacteria and that this response does not involve Defensin.