Abstract
Complement factor B (FB) mutant variants are associated with excessive complement activation in kidney diseases such as atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy and membranoproliferative glomerulonephritis (MPGN). Patients with aHUS are currently treated with eculizumab while there is no specific treatment for other complement-mediated renal diseases. In this study the phenotype of three FB missense variants, detected in patients with aHUS (D371G and E601K) and MPGN (I242L), was investigated. Patient sera with the D371G and I242L mutations induced hemolysis of sheep erythrocytes. Mutagenesis was performed to study the effect of factor D (FD) inhibition on C3 convertase-induced FB cleavage, complement-mediated hemolysis, and the release of soluble C5b-9 from glomerular endothelial cells. The FD inhibitor danicopan abrogated C3 convertase-associated FB cleavage to the Bb fragment in patient serum, and of the FB constructs, D371G, E601K, I242L, the gain-of-function mutation D279G, and the wild-type construct, in FB-depleted serum. Furthermore, the FD-inhibitor blocked hemolysis induced by the D371G and D279G gain-of-function mutants. In FB-depleted serum the D371G and D279G mutants induced release of C5b-9 from glomerular endothelial cells that was reduced by the FD-inhibitor. These results suggest that FD inhibition can effectively block complement overactivation induced by FB gain-of-function mutations.
| Original language | English |
|---|---|
| Article number | 690821 |
| Pages (from-to) | 690821 |
| Number of pages | 1 |
| Journal | Frontiers in Immunology |
| Volume | 12 |
| DOIs | |
| Publication status | Published - 10 Jun 2021 |
Bibliographical note
Funding Information: The authors wish to thank Dr Marina Noris and Dr Roberta Donadelli, Istituto di Ricerche Farmacologiche Mario Negri, Bergamo Italy for excellent technical advice for the assay of factor B cleavage by the C3 convertase. Dr Ravi Bhongir and Dr Sandra Jovic, Infection Medicine, Clinical Sciences Lund are acknowledged for their help with the surface plasmon resonance assays. The authors thank Drs Markus Heidenblad, Sofia Saal and Bj?rn Hallstr?m of the Center for Molecular Diagnostics, Region Sk?ne and Clinical Genomics Lund, SciLifeLab, Lund University for next-generation sequencing. Dr Henning Gong carried out part of the mutagenesis study as part of his master?s thesis. The kidney biopsies of Patient 3 were assessed by Dr. Melinda Raki, Department of Pathology, Oslo University Hospital, Oslo Norway, Dr. Sabine Leh, Department of Pathology, Haukeland Univeristy Hospital Bergen, Norway, Professor Sanjeev Sethi and Professor Fernando Fervenza of the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota. This work was presented in preliminary poster form at the17th Congress of the International Pediatric Nephrology Association, Iguacu Brazil, September 20-24, 2016, at the 6th International Conference ?HUS & related diseases?, Innsbruck, Austria, June 11-13, 2017, the 16th European Meeting of Complement in Human Disease, Copenhagen, Denmark, September 8-12, 2017, the 18th Congress of the International Pediatric Nephrology Association, Venice, Italy October 17-21, 2019. Publisher Copyright: © Copyright © 2021 Aradottir, Kristoffersson, Roumenina, Bjerre, Kashioulis, Palsson and Karpman.Other keywords
- Animals
- Atypical Hemolytic Uremic Syndrome/genetics
- C3 glomerulopathy
- Child
- Complement Activation
- Complement C3-C5 Convertases/immunology
- Complement C3b/immunology
- Complement Factor B/genetics
- Complement Factor D/antagonists & inhibitors
- Endothelial Cells/immunology
- Erythrocytes
- Female
- Glomerulonephritis, Membranoproliferative/genetics
- Hemolysis
- Humans
- Infant
- Kidney Glomerulus/cytology
- Male
- Middle Aged
- Mutation
- Phenotype
- Rabbits
- Sheep
- atypical hemolytic uremic syndrome
- complement
- danicopan
- factor B
- factor D
