动脉粥样硬化胞葬作用和相关微小RNA研究进展

动脉粥样硬化是心脑血管疾病发生、发展的主要病理基础。动脉粥样硬化形成中存在巨噬细胞胞葬缺陷。有缺陷的胞葬导致未清除的凋亡细胞堆积,继发性坏死,从而导致动脉粥样硬化特征性的坏死核心形成和斑块不稳定。完整的胞葬过程包括识别(“找我”)阶段、吞噬(“吃我”)阶段和后处理反应(吞噬后)阶段。已有报道miRNA在动脉粥样硬化胞葬中参与调节关键信号传导和脂质稳态。文章讨论了动脉粥样硬化过程中胞葬的重要作用及胞葬缺陷对动脉粥样硬化的影响,尤其针对胞葬吞噬阶段“吃我”和“不吃我”信号在动脉粥样硬化全程炎症参与下胞葬缺陷的调节影响、miRNA在动脉粥样硬化中调节脂质代谢及炎症消退、动脉粥样硬化过程中miRNA靶向巨噬细胞的胞葬的微调节作用等方面的研究文献进行综述。     

巨噬细胞增殖和凋亡与动脉粥样硬化

动脉粥样硬化（As）是一种由动脉壁脂质沉积所引发的一种病理生理过程,与巨噬细胞介导的慢性炎性反应高度相关。As早期,巨噬细胞通过吞噬作用清除斑块中修饰脂蛋白、细胞碎片和死亡细胞,限制斑块生长。随着病程进展,斑块中巨噬细胞凋亡增多且清除功能下降,引起继发性细胞坏死和炎性反应,促成不稳定斑块形成。巨噬细胞增殖和凋亡与As发生发展密切相关。本文主要针对巨噬细胞增殖和凋亡对As发生发展的影响做一综述,为As防治提供理论依据。     

巨噬细胞的吞噬功能与动脉粥样硬化斑块的稳定性

吞噬性清除凋亡细胞是巨噬细胞的重要生理功能,在动脉粥样硬化斑块的发生、发展和维护斑块的稳定性过程中具有重要作用.本文就巨噬细胞对凋亡细胞识别、摄取和吞噬的分子机制,以及在维护动脉粥样硬化斑块稳定性中的作用作一综述.     

巨噬细胞胞葬功能在急慢性肝病中的作用机制及其靶向治疗

胞葬作用是指吞噬细胞（包括巨噬细胞、树突状细胞等专职吞噬细胞和上皮细胞等非专职吞噬细胞）吞噬并清除凋亡细胞的过程。肝巨噬细胞是肝脏中具有胞葬功能的主要细胞。近年来,越来越多的研究表明包括急性肝损伤、酒精性肝病、非酒精性脂肪性肝病、自身免疫性肝病、肝纤维化及肝细胞癌等在内的多种急慢性肝病均与肝巨噬细胞的胞葬作用有关。本文通过阐述巨噬细胞胞葬相关分子的表达、胞葬过程及其胞葬功能在不同肝病中作用的最新研究进展,旨在为肝病治疗提供新思路。     

葛根总黄酮对载脂蛋白E基因缺陷小鼠动脉粥样硬化病变内细胞凋亡及凋亡相关基因的影响

目的 探讨葛根总黄酮对载脂蛋白E基因缺陷（apoE-／-）小鼠主动脉窦动脉粥样硬化斑块抑制作用的分子机制。方法 采用电镜观察、缺口末端标记（TUNEL）法检测apoE-／-小鼠动脉粥样硬化斑块内的细胞凋亡。免疫组化方法检测平滑肌细胞、巨噬细胞及Caspase一3蛋白的表达。结果 电镜观察到凋亡细胞核形不规则,胞核内染色质浓集、边聚,附着在核膜周边,线粒体肿胀,内质网扩张,超微结构形态符合巨噬细胞早期凋亡,并可见典型凋亡小体形成。TUNEL结果表明,凋亡细胞主要分布在粥样斑块脂质核心处,模型组动脉粥样硬化斑块内凋亡细胞数较多,而葛根总黄酮干预组凋亡细胞数明显减少,葛根高、低剂量组细胞凋亡率明显低于模型组[分别为（0．38±0．17）ok,（1．95±1．02）％,（10．50±5．89）％,P〈0．01],葛根高剂量组细胞凋亡率明显低于葛根低剂量组。抗CD68抗体免疫组化染色证实在动脉粥样硬化斑块脂质坏死核心内细胞CD68强阳性表达。葛根高、低剂量治疗组Caspase-3蛋白免疫表达低于模型组,葛根高剂量治疗组低于葛根低剂量治疗组。结论 葛根总黄酮可能通过下调apoE-／-小鼠主动脉窦动脉粥样硬化病变内Caspases-3蛋白的表达,显著降低了动脉粥样硬化病变内巨噬细胞凋亡,从而抑制了动脉粥样硬化斑块的进展。     

干扰素调节因子5通过损伤胞葬作用控制动脉粥样硬化病变中的坏死核心形成

正髓系细胞是动脉粥样硬化病变发展和易损斑块形成的核心。动脉吞噬细胞吸收凋亡细胞(胞葬作用)的能力受损,可促进病变生长并建立坏死核心。干扰素调节因子(interferon regulatory factor,IRF)5是髓系细胞功能的重要调节因子。该研究试图确定IRF5是否影响动脉粥样硬化病变的形成和表型。方法:通过两种互补模型,研究IRF5在动脉粥样硬化中的作用:     

巨噬细胞自噬在动脉粥样硬化中作用的研究进展

动脉粥样硬化(As)所致心脑血管疾病在全球的罹患率及致死率名居前列,严重威胁人类健康。血脂紊乱和氧化炎症等状态使血管内膜下巨噬细胞对胆固醇的多进少出,导致胞内积聚大量脂滴(LDs),演变为泡沫细胞,成为As斑块形成的中心环节。自噬是细胞一种保护性物质降解途径,基础性自噬有利于细胞的物质代谢平衡,但自噬缺陷或异常则使细胞清除能力下降,引发代谢应激、氧化、炎症及细胞死亡等,与As斑块发生发展密切相关。本文就巨噬细胞自噬在胆固醇代谢、炎症、氧化应激、凋亡等方面的作用作一综述。     

巨噬细胞凋亡与糖尿病动脉粥样硬化

在动脉粥样硬化性病变的进展过程中,一个关键的步骤就是易损斑块的形成.而巨噬细胞凋亡可促进斑块的进展,并与易损斑块形成密切相关.动脉粥样硬化性血管疾病是糖尿病主要并发症之一,因此总结与糖尿病相关的脂代谢紊乱、胰岛素抵抗、脂肪因子等巨噬细胞凋亡影响因素,并初步探讨其介导斑块内巨噬细胞凋亡的信号转导途径,对于防治糖尿病患者动脉粥样硬化具有重要意义.     

巨噬细胞凋亡与动脉粥样硬化

细胞凋亡是动脉粥样硬化病变的主要特征之一,其中巨噬细胞凋亡贯穿动脉粥样硬化的整个过程,而在成熟病变中,大多数凋亡细胞是紧邻脂核的巨噬细胞。激活的巨噬细胞虽具有一些保护作用,但总的作用还是促进动脉粥样硬化损伤的启动和发展,巨噬细胞死亡可导致细胞外脂质核的发生和扩大,对斑块破裂及血栓形成有重要影响。因此,动脉粥样硬化病灶中巨噬细胞的丧失可预测斑块的稳定性。本文主要从巨噬细胞凋亡在动脉粥样硬化病变过程中的机制及重要作用,以及与其他造成斑块不稳定性相关因素之间的关系加以阐述,更进一步阐明动脉粥样硬化的发病机制,从而为探索新的有效的临床防治策略提供可靠的理论基础。     

细胞水平胰岛素抵抗导致动脉粥样硬化斑块进展的研究

近期提出细胞水平胰岛素抵抗包括内皮细胞、平滑肌细胞和巨噬细胞,即粥样硬化斑块病变内细胞自身存在胰岛素信号通路的缺陷导致细胞生物学性能的改变,在动脉粥样硬化斑块进展中起关键作用.如斑块内细胞自身胰岛素抵抗可降低内皮细胞的舒张功能、平滑肌细胞的增殖、迁移并增加巨噬细胞凋亡和吞噬缺陷,导致粥样硬化斑块坏死核心的扩大.因此,深入了解细胞水平胰岛素抵抗参与动脉粥样硬化疾病发生、发展的机制为未来研发新型药物开辟新方向.     

Apoptotic cell death and efferocytosis in atherosclerosis

Apoptotic cell death is an important feature of atherosclerotic plaques, and it seems to exert both beneficial and detrimental effects depending on the cell type and plaque stage. Because late apoptotic cells can launch proatherogenic inflammatory responses, adequate engulfment of apoptotic cells (efferocytosis) by macrophages is important to withstand atherosclerosis progression. Several efferocytosis systems, composed of different phagocytic receptors, apoptotic ligands, and bridging molecules, can be distinguished. Because phagocytes in atherosclerotic plaques are very much solicited, a fully operative efferocytosis system seems to be an absolute requisite. Indeed, recent studies demonstrate that deletion of just 1 of the efferocytosis pathways aggravates atherosclerosis. This review discusses the role of apoptosis in atherosclerosis and general mechanisms of efferocytosis, to end with indirect and direct indications of the significance of effective efferocytosis in atherosclerosis.     

Role of caspases in death and survival of the plaque macrophage

This review considers the role of macrophage cell death in formation of the necrotic core and in plaque progression, and lists many of the possible mediators of macrophage cell death. Among these, perhaps the most cited toxic agent is oxidized low-density lipoprotein (oxLDL). Whereas oxLDL can kill macrophage, and whereas the form of death is morphologically apoptotic, caspase inhibitors appear to be ineffective in preventing death. This finding is consistent with recent literature showing how the canonical caspase pathways are used for physiological cellular functions other than cell death. Plaque macrophages appear to be among the cells with this nonapoptotic signaling function for activated caspases. In many of the other cell types, caspase activation appears to play a critical role in cell differentiation. We discuss possible functions of plaque macrophage using the nondeath caspase pathway. Recent literature shows that physiological and developmental functions of many cell types require active caspases without progressing to cell death. We discuss the role of macrophage cell death in plaque progression, possible mediators of macrophage cell death, and the possible functions of plaque macrophage using the nondeath caspase pathway.     

Consequences and therapeutic implications of macrophage apoptosis in atherosclerosis: the importance of lesion stage and phagocytic efficiency

Macrophage apoptosis occurs throughout all stages of atherosclerosis, yet new findings in vivo suggest that the consequences of this event may be very different in early versus late atherosclerotic lesions. In early lesions, where phagocytic clearance of apoptotic cells appears to be efficient, macrophage apoptosis is associated with diminished lesion cellularity and decreased lesion progression. In late lesions, however, a number of factors may contribute to defective phagocytic clearance of apoptotic macrophages, leading to secondary necrosis of these cells and a proinflammatory response. The cumulative effect of these late lesional events is generation of the necrotic core, which, in concert with proatherogenic effects of residual surviving macrophages, promotes further inflammation, plaque instability, and thrombosis. Thus, the ability or lack thereof of lesional phagocytes to safely clear apoptotic macrophages may be an important determinant of acute atherothrombotic clinical events. Further understanding of the mechanisms involved in macrophage apoptosis and phagocytic clearance might lead to novel therapeutic strategies directed against the progression of advanced plaques.     

Impaired apoptotic cell clearance in CGD due to altered macrophage programming is reversed by phosphatidylserine-dependent production of IL-4

Chronic granulomatous disease (CGD) is characterized by overexuberant inflammation and autoimmunity that are attributed to deficient anti-inflammatory signaling. Although regulation of these processes is complex, phosphatidylserine (PS)-dependent recognition and removal of apoptotic cells (efferocytosis) by phagocytes are potently anti-inflammatory. Since macrophage phenotype also plays a beneficial role in resolution of inflammation, we hypothesized that impaired efferocytosis in CGD due to macrophage skewing contributes to enhanced inflammation. Here we demonstrate that efferocytosis by macrophages from CGD (gp91(phox)(-/-)) mice was suppressed ex vivo and in vivo. Alternative activation with interleukin 4 (IL-4) normalized CGD macrophage efferocytosis, whereas classical activation by lipopolysaccharide (LPS) plus interferon gamma (IFNgamma) had no effect. Importantly, neutralization of IL-4 in wild-type macrophages reduced macrophage efferocytosis, demonstrating a central role for IL-4. This effect was shown to involve 12/15 lipoxygenase and activation of peroxisome-proliferator activated receptor gamma (PPARgamma). Finally, injection of PS (whose exposure is lacking on CGD apoptotic neutrophils) in vivo restored IL-4-dependent macrophage reprogramming and efferocytosis via a similar mechanism. Taken together, these findings support the hypothesis that impaired PS exposure on dying cells results in defective macrophage programming, with consequent efferocytic impairment and has important implications in understanding the underlying cause of enhanced inflammation in CGD.     

Necrotic cell death in atherosclerosis

Necrosis is a type of cell death characterized by a gain in cell volume, swelling of organelles, rupture of the plasma membrane and subsequent loss of intracellular contents. For a long time, the process has been considered as a merely accidental and uncontrolled form of cell death, but accumulating evidence suggests that it can also occur in a regulated fashion. Morphological studies using transmission electron microscopy indicate that the vast majority of dying cells in advanced human atherosclerotic plaques undergo necrosis. Various stimuli in the plaque including high levels of oxidative stress, depletion of cellular ATP, impaired clearance of apoptotic cells and increased intracellular calcium may cause necrotic death. Although the role of necrosis in atherosclerosis remains ill-defined, a growing body of evidence suggests that necrotic death stimulates atherogenesis through induction of inflammation and enlargement of the necrotic core. In addition, necrosis contributes to plaque instability by releasing tissue factor, matrix degrading proteases and pro-angiogenic compounds. Therapeutic agents against necrosis are limited, but efforts have recently been made to inhibit the necrotic pathway or its pro-inflammatory effects.     

Phagocytosis in atherosclerosis: Molecular mechanisms and implications for plaque progression and stability

Macrophages play a key role in atherosclerotic plaque destabilization and rupture. In this light, selective removal of macrophages may be beneficial for plaque stability. However, macrophages are phagocytic cells and thus have an important additional role in scavenging of modified lipoproteins, unwanted or dead cells and cellular debris via phagocytosis. The concept of phagocytosis as well as the underlying mechanisms is well defined but the effect of phagocytosis in terms of plaque stability remains poorly understood. Recent findings point towards a complex role of macrophage phagocytosis in atherogenesis. Macrophages are necessary for removal of apoptotic cells from plaques, but exert strong proatherogenic properties upon phagocytosis of lipoproteins, erythrocytes and platelets. Apart from heterophagy, autophagocytosis better known as autophagy may occur in advanced atherosclerotic plaques. Several lines of evidence indicate that autophagy is initiated in plaque smooth muscle cells as a result of cellular distress. Since autophagy is well recognized as a survival mechanism, autophagic smooth muscle cells in the fibrous cap may reflect an important feature underlying plaque stability. All together, phagocytosis is a crucial process involved in atherogenesis that may significantly affect the stability of the atherosclerotic plaque.     

Phenotypic High-Throughput Screening in Atherosclerosis Research: Focus on Macrophages

Atherosclerosis is a complex disease characterized by arterial lesions consisting of macrophage foam cells, smooth muscle cells, lymphocytes and other cell types. As atherosclerotic lesions mature, they can rupture and thereby trigger thrombosis that can result in tissue infarction. Macrophage foam cells develop in the subendothelial space when cells take up cholesterol from modified forms of low-density lipoprotein (LDL) and other apolipoprotein B-containing lipoproteins. Current therapies to limit atherosclerosis focus on altering the plasma lipid composition, most commonly by reducing circulating LDL levels. No current therapy is specifically designed to alter the cellular composition of atherosclerotic lesions. To address this deficit, phenotypic high-throughput drug screens have been developed to identify compounds that reduce the uptake of oxidized LDL by macrophages or to identify compounds that increase the efflux of cholesterol from macrophages. Additional phenotypic screens can be envisaged that address cellular processes in active atherosclerotic lesions including macrophage apoptosis and efferocytosis.     

Molecular and cellular mechanisms of macrophage survival in atherosclerosis

Macrophages play a key role in the initiation and progression of atherosclerotic plaques. Although a significant number of macrophages undergoes cell death during plaque development as a result of atherogenic stressors, advanced plaques are characterized by a large macrophage content. Macrophage accumulation is mediated by continuous recruitment of monocytes, reduced emigration of macrophages and poor phagocytosis of dead cells which may trigger secondary necrosis and amplification of plaque inflammation. Moreover, an increasing body of evidence indicates that macrophages have developed several strategies to survive and to proliferate in the adverse environment of an advanced atherosclerotic plaque. Macrophages contain organic molecules or enzymes that provide enhanced antioxidant protection. In addition, synthesis of anti-apoptotic proteins is upregulated and several cellular protection mechanisms such as the unfolded protein response and autophagy are activated in macrophages to promote cellular survival. In this review, we discuss these macrophage survival mechanisms that allow growth and destabilization of advanced atherosclerotic plaques.     

CD68-阳性巨噬细胞在人冠状动脉粥样硬化病变中的分布特点及其意义

目的 探讨人冠状动脉粥样硬化病变中CD68-阳性巨噬细胞的分布以及与冠状动脉粥样硬化病变类型、管腔狭窄之间的关系及其意义.方法 选用53例尸检病例的312块冠状动脉组织标本,光镜下诊断弥漫性内膜增厚和冠状动脉粥样硬化病变及其类型,用免疫组织化学计数冠状动脉粥样硬化病变中CD68-阳性巨噬细胞,用Scion图像软件系统检测和计算冠状动脉标本中管腔狭窄程度、脂质坏死核心和钙化基质面积.结果 在冠状动脉粥样病变中, 40% (124/312)为弥漫性内膜增厚, 5% (16/312)为Ⅰ型, 10% (31/312)为Ⅱ型, 21% (66/312)为Ⅲ型, 4% (14/312)为Ⅳ型, 18% (55/312)为Ⅴ型和2% (6/312)为Ⅵ型.脂质坏死核心面积在高胆固醇组明显大于正常胆固醇组(P<0.05),而钙化基质面积在早期病变(Ⅰ～Ⅲ型)和进展期病变(Ⅳ～Ⅵ型)之间有显著性差异(P<0.05);冠状动脉粥样硬化病变CD68-阳性巨噬细胞随着冠状动脉粥样硬化病变进展和管腔狭窄程度的加重而增多,分别呈正相关(P<0.01),且不同病变类型、管腔狭窄程度之间以及正常胆固醇组与高胆固醇组之间有显著性差异(P<0.05).结论 CD68-阳性巨噬细胞随着人冠状动脉粥样硬化病变进展和管腔狭窄程度的加重而增多,表明巨噬细胞浸润始终始发和加重冠状动脉粥样硬化病变,大量巨噬细胞主要在斑块肩部区浸润和脂质坏死核心的增大与冠状动脉粥样硬化病变进展、不稳定性斑块破裂及并发症的发生有关.     

神经导向因子Netrin-1调节单核巨噬细胞迁移与动脉粥样斑块关系的研究进展

动脉粥样硬化是动脉壁的一种慢性炎症性疾病,单核巨噬细胞在其发生发展中起着关键作用。动脉粥样斑块中单核巨噬细胞迁移能力受损,滞留于斑块内,增加了斑块不稳定性,加速动脉粥样硬化病变的进展。目前研究表明动脉粥样斑块中巨噬细胞分泌的神经导向因子Netrin-1通过与巨噬细胞表面相应受体结合,可以抑制巨噬细胞迁出斑块,促进动脉粥样硬化的进展。但在动脉粥样硬化形成初期,血管内皮细胞表达的Netrin-1却被发现对动脉粥样硬化起到保护作用。