2019
J Clin Invest. 2019 Mar 1;129(3):1061-1075. doi: 10.1172/JCI99296. Epub 2019 Feb 4.
Hyperfunctional complement C3 promotes C5-dependent atypical hemolytic uremic syndrome in mice.
Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom. The National Renal Complement Therapeutics Centre (NRCTC), Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom. Department of Chemistry, University of Edinburgh, Edinburgh, United Kingdom. Division of Rheumatology, Washington University in St. Louis, St. Louis, Missouri, USA. Department of Medicine, Imperial College London, London, United Kingdom.
Service type: Knock-in mice
Abstract
Atypical hemolytic uremic syndrome (aHUS) is frequently associated in humans with loss-of-function mutations in complement-regulating proteins or gain-of-function mutations in complement-activating proteins. Thus, aHUS provides an archetypal complement-mediated disease with which to model new therapeutic strategies and treatments. Herein, we show that, when transferred to mice, an aHUS-associated gain-of-function change (D1115N) to the complement-activation protein C3 results in aHUS. Homozygous C3 p.D1115N (C3KI) mice developed spontaneous chronic thrombotic microangiopathy together with hematuria, thrombocytopenia, elevated creatinine, and evidence of hemolysis. Mice with active disease had reduced plasma C3 with C3 fragment and C9 deposition within the kidney. Therapeutic blockade or genetic deletion of C5, a protein downstream of C3 in the complement cascade, protected homozygous C3KI mice from thrombotic microangiopathy and aHUS. Thus, our data provide in vivo modeling evidence that gain-of-function changes in complement C3 drive aHUS. They also show that long-term C5 deficiency is not accompanied by development of other renal complications (such as C3 glomerulopathy) despite sustained dysregulation of C3. Our results suggest that this preclinical model will allow testing of novel complement inhibitors with the aim of developing precisely targeted therapeutics that could have application in many complement-mediated diseases.
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