自噬与固有免疫应答相互调节研究进展

自噬在细胞分化、肿瘤、炎症、免疫等多方面发挥关键作用.近年来,随着分子生物学、细胞生物学、免疫学等学科的发展,研究发现细胞自噬与固有免疫应答有着重要的相互调控作用.自噬是固有免疫的重要组成成分,可以通过溶酶体直接降解被自噬体包裹的病原体.自噬参与众多固有免疫信号的调控.固有免疫信号也诱导或抑制自噬.自噬在抗胞内病原体感染中发挥重要作用.     

细胞自噬机制开启疾病治疗新途径

自噬是指细胞内细胞器和蛋白质等在溶酶体被降解及其降解产物被重新利用的过程。日本科学家大隅良典(Yoshinori Ohsumi)发现了15个自噬相关基因并阐述了自噬机制,获得2016年诺贝尔生理学与医学奖。他的开创性研究成果为探讨细胞自噬的生理和病理作用奠定了重要基础,并为通过调节细胞自噬治疗疾病开辟了新途径。自噬是一种普遍性细胞反应,正常情况下细胞自噬水平很低,受生理或病理性刺激后自噬水平显著升高。自噬相关基因缺失或自噬功能障碍时可导致某些疾病的发生。近来,人们试图通过激活或抑制细胞自噬预防和治疗自噬障碍相关性疾病。     

病毒感染与细胞自噬的交互作用

细胞自噬为机体维持内环境稳定并降解胞内成分的一种溶酶体清除程序。在病毒感染过程中, 自噬发挥双向作用。自噬可以在固有免疫中通过自噬溶酶体直接消化清除胞内病原体, 另一方面, 病毒也会影响或利用自噬使自身得以逃避机体免疫反应。文章就病毒感染与细胞自噬的交互作用作一综述。     

巨噬细胞的自噬及其在抗结核分枝杆菌感染中的作用

白噬是广泛存在于真核细胞内的一种溶酶体依赖性的自降解途径,可通过降解长寿蛋白和受损细胞器维持细胞内的平衡。近年来的研究发现,巨噬细胞的自噬还是固有免疫和适应性免疫的重要组成部分,可参与胞内感染病原体的清除。目前已发现有多种途径参与自噬的诱导和调节。在感染的巨噬细胞内,诱导自噬的发生能促进吞噬体和溶酶体的融合,抑制胞内结核分枝杆菌（Mtb）的存活。但同时Mtb也可通过某些机制抑制巨噬细胞自噬的发生以逃避巨噬细胞的杀伤,进而长期持留于巨噬细胞内。深入了解巨噬细胞自噬与胞内Mtb相互作用的机制,有助于人类更好的预防和控制结核病。     

细胞自噬与动脉粥样硬化关系的研究进展

自噬是一种降解病原体和相关细胞器尤其是损伤的线粒体的分子机制,自噬也可清除其他的细胞成分,例如炎症和细胞因子,这为抗炎症提供了重要的途径.相关研究发现,自噬的产生或降解能够影响动脉粥样硬化斑块的发展过程.因此,在疾病出现时,自噬的调节对于疾病治疗的靶点具有重要的意义.然而,在正常情况和炎症反应时,自噬的调节方式是多方面的.这些错综复杂的改变是通过炎症和环境刺激所产生的,这对于了解和揭示自噬调节的炎症和提供相应的治疗方案是必不可少的.因而人了解自噬的分子机制,以及血管内皮细胞、血管平滑肌细胞、巨噬细胞自噬在动脉粥样硬化中起到的作用对于疾病的发展和靶向治疗具有重要意义.     

细胞自噬的调控与自噬程序性死亡的研究进展

自噬(autophagy)是一种溶酶体依赖性降解途径,涉及细胞内长寿蛋白和受损伤细胞器的降解,其既是细胞保守的自我防御机制,又是一种程序性细胞死亡机制(PCD),与机体的多种疾病有密切关系.自噬具有独特的形态改变和特有的调控通路,自噬的调控涉及到多种机制、如翻译后修饰等.凋亡是研究最清楚的程序性细胞死亡机制,凋亡与细胞自噬程序性死亡之间存在着复杂的关系.对哺乳动物细胞自噬的分子调控机制,自噬程序性细胞死亡过程及其与凋亡的关系等方面进行探讨很有意义.     

自噬与病毒复制

自噬是真核生物中一类保守的胁迫机制,是溶酶体蛋白降解途径的主要形式之一.自噬通过降解衰老损伤的细胞器和老龄蛋白维持细胞内稳态(homeostasis),同时通过吞噬细胞内微生物病原体行使天然免疫功能.在不同病毒感染过程中,自噬也可以发挥不同的作用：既能阻止病毒复制也可以促进病毒复制.当自噬发挥抗病毒作用时,通过包裹病毒...     

巨噬细胞的自噬及其在抗结核分枝杆菌感染中的作用

自噬是广泛存在于真核细胞内的一种溶酶体依赖性的自降解途径,可通过降解长寿蛋白和受损细胞器维持细胞内的平衡.近年来的研究发现,巨噬细胞的自噬还是固有免疫和适应性免疫的重要组成部分,可参与胞内感染病原体的清除.目前已发现有多种途径参与自噬的诱导和调节.在感染的巨噬细胞内,诱导自噬的发生能促进吞噬体和溶酶体的融合,抑制胞内结核分枝杆菌(Mtb)的存活.但同时Mtb也可通过某些机制抑制巨噬细胞自噬的发生以逃避巨噬细胞的杀伤,进而长期持留于巨噬细胞内.深入了解巨噬细胞自噬与胞内Mtb相互作用的机制,有助于人类更好的预防和控制结核病.     

细胞自噬的形态学特征和功能意义

目的 自噬是细胞受到刺激后吞噬自身的细胞质或细胞器,最终将吞噬物在溶酶体内降解的过程.按吞噬物进入溶酶体的途径,自噬可分为巨自噬、微自噬和分子伴侣介导的自噬3类.在巨自噬,自噬前体包裹细胞质或细胞器后形成自噬体,继而自噬体与溶酶体结合形成自噬溶酶体,自噬体内容物被降解.在微自噬,溶酶体膜凹陷,直接吞噬细胞质、细胞器或细胞核,形成自噬体,然后被溶酶体酶降解.分子伴侣介导的自噬是通过溶酶体膜的受体将细胞质内的蛋白质转运入溶酶体.自噬从酵母至哺乳动物细胞均很保守,对于耐受饥饿和缺血,清除衰老细胞器,清除细菌和异物,维持细胞活性和延长寿命等起着重要作用.自噬活动受自噬基因的调控,自噬基因缺失或功能障碍时可导致某些疾病的发生.深入认识自噬过程以及由此产生的自噬体等结构及其功能有助于探讨自噬对于人体生理和病理作用的机制.本文综述了自噬的形态学特征及其功能意义.     

线粒体自噬在器官纤维化疾病中作用的研究进展

线粒体自噬是一种选择性降解细胞中损伤或多余线粒体的特异性自噬现象,使细胞在应激损伤时能够维持线粒体数量和质量的稳定,从而维持细胞的正常表型和功能。其分子机制途径较为复杂,主要涉及PINK1/Parkin途径、NIX和BNIP3、FUNDC1等。线粒体自噬的异常与多种疾病密切相关,而调节不同阶段线粒体自噬分子机制在疾病发展中的作用已被重视。现就近年线粒体自噬在多种器官纤维化病变中的研究进展综述如下。     

The effect of fasting or calorie restriction on autophagy induction: A review of the literature

Autophagy is a lysosomal degradation process and protective housekeeping mechanism to eliminate damaged organelles, long-lived misfolded proteins and invading pathogens. Autophagy functions to recycle building blocks and energy for cellular renovation and homeostasis, allowing cells to adapt to stress. Modulation of autophagy is a potential therapeutic target for a diverse range of diseases, including metabolic conditions, neurodegenerative diseases, cancers and infectious diseases. Traditionally, food deprivation and calorie restriction (CR) have been considered to slow aging and increase longevity. Since autophagy inhibition attenuates the anti-aging effects of CR, it has been proposed that autophagy plays a substantive role in CR-mediated longevity. Among several stress stimuli inducers of autophagy, fasting and CR are the most potent non-genetic autophagy stimulators, and lack the undesirable side effects associated with alternative interventions. Despite the importance of autophagy, the evidence connecting fasting or CR with autophagy promotion has not previously been reviewed. Therefore, our objective was to weigh the evidence relating the effect of CR or fasting on autophagy promotion. We conclude that both fasting and CR have a role in the upregulation of autophagy, the evidence overwhelmingly suggesting that autophagy is induced in a wide variety of tissues and organs in response to food deprivation.     

Autophagy in innate recognition of pathogens and adaptive immunity

Autophagy is a specialized cellular pathway involved in maintaining homeostasis by degrading long-lived cellular proteins and organelles. Recent studies have demonstrated that autophagy is utilized by immune systems to protect host cells from invading pathogens and regulate uncontrolled immune responses. During pathogen recognition, induction of autophagy by pattern recognition receptors leads to the promotion or inhibition of consequent signaling pathways. Furthermore, autophagy plays a role in the delivery of pathogen signatures in order to promote the recognition thereof by pattern recognition receptors. In addition to innate recognition, autophagy has been shown to facilitate MHC class II presentation of intracellular antigens to activate CD4 T cells. In this review, we describe the roles of autophagy in innate recognition of pathogens and adaptive immunity, such as antigen presentation, as well as the clinical relevance of autophagy in the treatment of human diseases.     

Xenophagic pathways and their bacterial subversion in cellular self-defense – παντα ρει – everything is in flux

Autophagy is an evolutionarily ancient and highly conserved eukaryotic mechanism that targets cytoplasmic material for degradation. Autophagic flux involves the formation of autophagosomes and their degradation by lysosomes. The process plays a crucial role in maintaining cellular homeostasis and responds to various environmental conditions. While autophagy had previously been thought to be a non-selective process, it is now clear that it can also selectively target cellular organelles, such as mitochondria (referred to as mitophagy) and/or invading pathogens (referred to as xenophagy). Selective autophagy is characterized by specific substrate recognition and requires distinct cellular adaptor proteins. Here we review xenophagic mechanisms involved in the recognition and autolysosomal or autophagolysosomal degradation of different intracellular bacteria. In this context, we also discuss a recently discovered cellular self-defense pathway, termed mito-xenophagy, which occurs during bacterial infection of dendritic cells and depends on a TNF-α-mediated metabolic switch from oxidative phosphorylation to glycolysis.     

Involvement of autophagy in viral infections: antiviral function and subversion by viruses

Autophagy is a cellular process involved in the degradation and turn-over of long-lived proteins and organelles, which can be subjected to suppression or further induction in response to different stimuli. According to its essential role in cellular homeostasis, autophagy has been implicated in several pathologies including cancer, neurodegeneration and myopathies. More recently, autophagy has been described as a mechanism of both innate and adaptive immunity against intracellular bacteria and viruses. In this context, autophagy has been proposed as a protective mechanism against viral infection by degrading the pathogens into autolysosomes. This is strengthened by the fact that several proteins involved in interferon (IFN) signalling pathways are linked to autophagy regulation. However, several viruses have evolved strategies to divert IFN-mediated pathways and autophagy to their own benefit. This review provides an overview of the autophagic process and its involvement in the infection by different viral pathogens and of the connections existing between autophagy and proteins involved in IFN signalling pathways.     

自噬的免疫调节作用和机制

自噬是细胞内降解细胞成分的主要通道,对生物体的生存、分化、发育和维持其动态平衡具有关键作用。自噬机制既可作为免疫系统清除细胞内病原物质的效应器,也可作为模式识别受体或细胞因子的效应器,帮助免疫系统确认病原侵入和细胞转化。更为重要的是,自噬过程还可通过将细胞内物质转移到溶酶体降解并呈递给Ⅱ型MHC分子,与细胞应激和炎症反应耦联,参与调节固有免疫和适应性免疫反应。对自噬参与免疫反应分子机制的研究将加深对免疫反应分子机制的全面了解,为自噬相关疾病防治提供新的机会和途径。     

Porcine circovirus type 2 explores the autophagic machinery for replication in PK-15 cells

Porcine circovirus type 2 (PCV2), an important pathogen of pigs, causes lymphoid depletion in infected tissues most probably by inducing apoptosis although the precise pathogenesis of PCV2-associated diseases remains unknown. We speculate whether autophagy, another cellular response to stress or infections by bacterial or viral pathogens, is involved in PCV2 infection. Here, we provide the first evidence that PCV2 could trigger autophagosome formation and enhance autophagic flux in PK-15 cells, most likely by its capsid protein. Using activators or inhibitors including siRNA targeting atg5, autophagy was found to enhance viral replication and capsid protein expression. These results suggest that PCV2 might employ the autophagy machinery to enhance its replication in host cells, thus raising the possibility of targeting autophagic pathway as a potential antiviral strategy against PCV2 infection.     

Autophagy as an emerging dimension to adaptive and innate immunity

Autophagy is an evolutionary conserved cellular process during which cytoplasmic material is engulfed in double membrane vacuoles that then fuse with lysosomes, ultimately degrading their cargo. Emerging evidence, however, now suggests that autophagy can form part of our innate and adaptive immune defense programs. Recent studies have identified pattern recognition molecules as mediators of this process and shown that intracellular pathogens can interact with and even manipulate autophagy. Recent translational evidence has also implicated autophagy in the pathogenesis of several immune-mediated diseases, including Crohn disease. In this review, we present autophagy in the context of its role as an immune system component and effector and speculate on imminent and future research directions in this field.