van Beek Johan, Elward Kristina, Gasque Philippe
Brain Inflammation and Immunity Group, Department of Medical Biochemistry and Immunology, University of Wales College of Medicine, Cardiff, UK.
Ann N Y Acad Sci. 2003 May;992:56-71. doi: 10.1111/j.1749-6632.2003.tb03138.x.
The complement system is an essential effector of the humoral and cellular immunity involved in cytolysis and immune/inflammatory responses. Complement participates in host defense against pathogens by triggering the formation of the membrane attack complex. Complement opsonins (C1q, C3b, and iC3b) interact with surface complement receptors to promote phagocytosis, whereas complement anaphylatoxins C3a and C5a initiate local inflammatory responses that ultimately contribute to the protection and healing of the host. However, activation of complement to an inappropriate extent has been proposed to promote tissue injury. There is now compelling evidence that complement activation in the brain is a double-edged sword in that it can exert beneficial or detrimental effects depending on the pathophysiological context. This review focuses on the roles of the complement system in the pathogenesis of acute brain injury (cerebral ischemia and trauma) and chronic neurodegeneration (Alzheimer's disease). Because many effects of the complement appear to promote neuronal survival and tissue remodeling, directing activation of the complement system in the brain may provide a better therapeutic rationale than inhibiting it.
补体系统是体液免疫和细胞免疫的重要效应器，参与细胞溶解及免疫/炎症反应。补体通过触发膜攻击复合物的形成参与宿主对病原体的防御。补体调理素（C1q、C3b和iC3b）与表面补体受体相互作用以促进吞噬作用，而补体过敏毒素C3a和C5a引发局部炎症反应，最终有助于宿主的保护和愈合。然而，有人提出补体过度激活会促进组织损伤。现在有确凿的证据表明，大脑中的补体激活是一把双刃剑，因为根据病理生理背景，它可能产生有益或有害的影响。本综述重点关注补体系统在急性脑损伤（脑缺血和创伤）和慢性神经退行性变（阿尔茨海默病）发病机制中的作用。由于补体的许多作用似乎促进神经元存活和组织重塑，因此指导大脑中补体系统的激活可能比抑制它提供更好的治疗原理。
