肝损伤机制。II. 肝脏缺血再灌注及其他急性炎症状态下中性粒细胞诱导肝细胞损伤的机制。
Mechanisms of Liver Injury. II. Mechanisms of neutrophil-induced liver cell injury during hepatic ischemia-reperfusion and other acute inflammatory conditions.
作者信息
Jaeschke Hartmut
机构信息
Liver Research Institute, College of Medicine, University of Arizona, Tucson, 85724, USA.
出版信息
Am J Physiol Gastrointest Liver Physiol. 2006 Jun;290(6):G1083-8. doi: 10.1152/ajpgi.00568.2005.
Polymorphonuclear leukocytes (neutrophils) are a vital part of the innate immune response to microbial infections and tissue trauma, e.g., ischemia-reperfusion injury, in many organs including the liver. However, an excessive inflammatory response can lead to a dramatic aggravation of the existing injury. To design interventions, which selectively target the detrimental effects of neutrophils, a detailed understanding of the pathophysiology is critical. Systemic or local exposure to proinflammatory mediators causes activation and priming of neutrophils for reactive oxygen formation and recruits them into the vascular beds of the liver without causing tissue injury. However, generation of a chemotactic signal from the parenchyma will trigger extravasation and an attack on target cells (e.g., hepatocytes). Adhesion to the target induces degranulation with release of proteases and formation of reactive oxygen species including hydrogen peroxide and hypochlorous acid, which can diffuse into hepatocytes and induce an intracellular oxidant stress and mitochondrial dysfunction. Various neutrophil-derived proteases are involved in transmigration and cell toxicity but can also promote the inflammatory response by processing of proinflammatory mediators. In addition, necrotic cells release mediators, e.g., high-mobility group box-1, which further promotes neutrophilic hepatitis and tissue damage. On the basis of these evolving insights into the mechanisms of neutrophil-mediated liver damage, the most selective strategies appear not to interfere with the cytotoxic potential of neutrophils, but rather strengthen the target cells' defense mechanisms including enhancement of the intracellular antioxidant defense systems, activation of cell survival pathways, or initiation of cell cycle activation and regeneration.
多形核白细胞(中性粒细胞)是对包括肝脏在内的许多器官中的微生物感染和组织损伤(如缺血-再灌注损伤)产生先天性免疫反应的重要组成部分。然而,过度的炎症反应会导致现有损伤急剧加重。为了设计能够选择性针对中性粒细胞有害作用的干预措施,深入了解病理生理学至关重要。全身或局部暴露于促炎介质会导致中性粒细胞活化并引发活性氧生成的预激发,并将它们募集到肝脏的血管床中而不引起组织损伤。然而,实质细胞产生的趋化信号将触发细胞外渗并对靶细胞(如肝细胞)发起攻击。与靶细胞的粘附会诱导脱颗粒,释放蛋白酶并形成包括过氧化氢和次氯酸在内的活性氧,这些活性氧可以扩散到肝细胞中并诱导细胞内氧化应激和线粒体功能障碍。多种源自中性粒细胞的蛋白酶参与迁移和细胞毒性,但也可通过加工促炎介质来促进炎症反应。此外,坏死细胞会释放介质,如高迁移率族蛋白盒1,这会进一步促进嗜中性肝炎和组织损伤。基于对中性粒细胞介导的肝损伤机制的这些不断深入的认识,最具选择性的策略似乎不是干扰中性粒细胞的细胞毒性潜力,而是加强靶细胞的防御机制,包括增强细胞内抗氧化防御系统、激活细胞存活途径或启动细胞周期激活和再生。