title: Overview of complement activation and regulation.
abstract: Complement is an important component of the innate immune system that is crucial for defense from microbial infections and for clearance of immune complexes and injured cells. In normal conditions complement is tightly controlled by a number of fluid-phase and cell surface proteins to avoid injury to autologous tissues. When complement is hyperactivated, as occurs in autoimmune diseases or in subjects with dysfunctional regulatory proteins, it drives a severe inflammatory response in numerous organs. The kidney appears to be particularly vulnerable to complement-mediated inflammatory injury. Injury may derive from deposition of circulating active complement fragments in glomeruli, but complement locally produced and activated in the kidney also may have a role. Many kidney disorders have been linked to abnormal complement activation, including immune-complex-mediated glomerulonephritis and rare genetic kidney diseases, but also tubulointerstitial injury associated with progressive proteinuric diseases or ischemia-reperfusion.
authors.affiliation: IRCCS- Istituto di Ricerche Farmacologiche "Mario Negri", Bergamo, Italy. Electronic address: marina.noris@marionegri.it.
authors.forename: Marina
authors.initials: M
authors.lastname: Noris
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Remuzzi
mesh_terms: D056704:Adaptive Immunity / Q000502:physiology*; D003166:Complement Activating Enzymes / Q000378:metabolism*; D003167:Complement Activation / Q000502:physiology*; D003165:Complement System Proteins; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D007674:Kidney Diseases / Q000276:immunology* / Q000378:metabolism
chemical_list: D003165:Complement System Proteins; D003166:Complement Activating Enzymes
keywords: Complement; adaptive immunity; complement regulators; innate immunity; kidney; kidney diseases