Complement in neurobiology.

The complement (C) system is a vital arm of innate immunity with many roles, including control of inflammation. This article examines the (C) system with emphasis on recent developments on complement relevant to neurobiology, in particular regarding our understanding and treatment of immune-mediated diseases. We will briefly outline the C system, and provide an updated review of its many receptors and regulatory factors. This section concludes with a listing of important roles of the C system, from recruitment of neural stem/progenitor cells, to its' relation to coagulation and adaptive immunity, and its lesser-known but beneficial roles in physiology. We also review evidence for C-mediated diseases, which include multiple sclerosis and Alzheimer's disease. Therapeutic approaches for C-mediated diseases, considers emphasizing modulators of the C system including several less widely studied approaches such as heparinoids, vitamin D, and intravenous IgM. Finally, we summarize cutting-edge work on the role of C-mediated natural antibodies in autoimmunity and treatment strategies based on those findings, e.g., for remyelination and post-ischemic stroke repair. Improved understanding of the C system may hold great promise for the treatment of neurodegenerative diseases.