Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1763, USA.
Acta Neuropathol. 2010 Jan;119(1):7-35. doi: 10.1007/s00401-009-0619-8. Epub 2009 Dec 10.
Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions.
星形胶质细胞是一种特化的神经胶质细胞，数量是神经元的五倍以上。它们连续排列在整个中枢神经系统（CNS）中，并在健康的 CNS 中发挥许多重要的复杂功能。星形胶质细胞通过一种称为反应性星形胶质细胞增生的过程对所有形式的 CNS 损伤作出反应，这已成为 CNS 结构损伤的病理标志。最近在确定反应性星形胶质细胞的功能和机制以及鉴定星形胶质细胞在 CNS 疾病和病变中的作用方面取得了重大进展。反应性星形胶质细胞可利用的大量分子武器正在被确定。转基因小鼠模型正在体内剖析反应性星形胶质细胞增生和神经胶质瘢痕形成的特定方面。星形胶质细胞在特定临床病理实体中的参与正在被确定。现在很清楚，反应性星形胶质细胞增生不是一种简单的全有或全无的现象，而是一种在特定信号事件调节下以上下文依赖方式发生的精细渐变连续变化。这些变化范围从基因表达和细胞肥大的可逆改变，伴随着细胞区域和组织结构的保留，到组织结构重排的持久瘢痕形成。越来越多的证据表明，反应性星形胶质细胞增生可能通过正常星形胶质细胞功能的丧失或异常效应的获得，在 CNS 疾病中发挥主要或辅助作用。本文综述了（1）健康 CNS 中的星形胶质细胞功能，（2）反应性星形胶质细胞增生和神经胶质瘢痕形成的机制和功能，以及（3）反应性星形胶质细胞如何导致或促成特定的 CNS 疾病和病变。
