期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2011
卷号：108
期号：21
页码：8761-8766
DOI：10.1073/pnas.1019338108
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Common polymorphisms in complement alternative pathway (AP) proteins C3 (C3R102G), factor B (fBR32Q), and factor H (fHV62I) are associated with age-related macular degeneration (AMD) and other pathologies. Our published work showed that fBR32Q influences C3 convertase formation, whereas fHV62I affects factor I cofactor activity. Here we show how C3R102G (C3S/F) influences AP activity. In hemolysis assays, C3102G activated AP more efficiently (EC50 C3102G: 157 nM; C3102R: 191 nM; P < 0.0001). fB binding kinetics and convertase stability were identical, but native and recombinant fH bound more strongly to C3b102R (KD C3b102R: 1.0 {micro}M; C3b102G: 1.4 {micro}M; P < 0.0001). Accelerated decay was unaltered, but fH cofactor activity was reduced for C3b102G, favoring AP amplification. Combining disease "risk" variants (C3102G, fB32R, and fH62V) in add-back assays yielded sixfold higher hemolytic activity compared with "protective" variants (C3102R, fB32Q, and fH62I; P < 0.0001). These data introduce the concept of a functional complotype (combination of polymorphisms) defining complement activity in an individual, thereby influencing susceptibility to AP-driven disease.
