Objective Perianal Crohn’s disease (pCD) occurs in up to 40% of patients with CD and is associated with poor quality of life, limited treatment responses and poorly understood aetiology. We performed a genetic association study comparing CD subjects with and without perianal disease and subsequently performed functional follow-up studies for a pCD associated SNP in Complement Factor B (CFB).
Design Immunochip-based meta-analysis on 4056 pCD and 11 088 patients with CD from three independent cohorts was performed. Serological and clinical variables were analysed by regression analyses. Risk allele of rs4151651 was introduced into human CFB plasmid by site-directed mutagenesis. Binding of recombinant G252 or S252 CFB to C3b and its cleavage was determined in cell-free assays. Macrophage phagocytosis in presence of recombinant CFB or serum from CFB risk, or protective CD or healthy subjects was assessed by flow cytometry.
Results Perianal complications were associated with colonic involvement, OmpC and ASCA serology, and serology quartile sum score. We identified a genetic association for pCD (rs4151651), a non-synonymous SNP (G252S) in CFB, in all three cohorts. Recombinant S252 CFB had reduced binding to C3b, its cleavage was impaired, and complement-driven phagocytosis and cytokine secretion were reduced compared with G252 CFB. Serine 252 generates a de novo glycosylation site in CFB. Serum from homozygous risk patients displayed significantly decreased macrophage phagocytosis compared with non-risk serum.
Conclusion pCD-associated rs4151651 in CFB is a loss-of-function mutation that impairs its cleavage, activation of alternative complement pathway, and pathogen phagocytosis thus implicating the alternative complement pathway and CFB in pCD aetiology.
- INFLAMMATORY BOWEL DISEASE
- IBD - GENETICS
Data availability statement
Data are available on reasonable request. Meta-analysis summary statistics will be made available on publication through the NIDDK IBD Genetics Consortium (IBDGC) Data Commons portal currently under development.
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DPBM and KSM are joint senior authors.
MA and TH contributed equally.
DPBM and KSM contributed equally.
Collaborators International IBD Genetics Consortium, Members of the International Inflammatory Bowel Disease Genetics Consortium: Clara Abraham, Jean-Paul Achkar, Tariq Ahmad, Leila Amininejad, Ashwin N Ananthakrishnan, Vibeke Andersen, Carl A Anderson, Jane M Andrews, Vito Annese, Guy Aumais, Leonard Baidoo, Robert N Baldassano, Peter A Bampton, Murray Barclay, Jeffrey C Barrett, Theodore M Bayless, Johannes Bethge, Alain Bitton, Gabrielle Boucher, Stephan Brand, Berenice Brandt, Steven R Brant, Carsten Büning, Angela Chew, Judy H Cho, Isabelle Cleynen, Ariella Cohain, Anthony Croft, Mark J Daly, Mauro D’Amato, Silvio Danese, Dirk De Jong, Martine De Vos, Goda Denapiene, Lee A Denson, Kathy L Devane, Olivier Dewit, Renata D’Inca, Marla Dubinsky, Richard H Duerr, Cathryn Edwards, David Ellinghaus, Jonah Essers, Lynnette R Ferguson, Eleonora A Festen, Philip Fleshner, Tim Florin, Denis Franchimont, Andre Franke, Karin Fransen, Richard Gearry, Michel Georges, Christian Gieger, Jürgen Glas, Philippe Goyette, Todd Green, Anne M Griffiths, Stephen L Guthery, Hakon Hakonarson, Jonas Halfvarson, Katherine Hanigan, Talin Haritunians, Ailsa Hart, Chris Hawkey, Nicholas K Hayward, Matija Hedl, Paul Henderson, Xinli Hu, Hailiang Huang, Jean-Pierre Hugot, Ken Y Hui, Marcin Imielinski, Andrew Ippoliti, Laimas Jonaitis, Luke Jostins, Tom H Karlsen, Nicholas A Kennedy, Mohammed Azam Khan, Gediminas Kiudelis, Krupa Krishnaprasad, Subra Kugathasan, Limas Kupcinskas, Anna Latiano, Debby Laukens, Ian C Lawrance, James C Lee, Charlie W Lees, Marcis Leja, Johan Van Limbergen, Paolo Lionetti, Jimmy Z Liu, Edouard Louis, Gillian Mahy, John Mansfield, Dunecan Massey, Christopher G Mathew, Dermot PB McGovern, Raquel Milgrom, Mitja Mitrovic, Grant W Montgomery, Craig Mowat, William Newman, Aylwin Ng, Siew C Ng, Sok Meng Evelyn Ng, Susanna Nikolaus, Kaida Ning, Markus Nöthen, Ioannis Oikonomou, Orazio Palmieri, Miles Parkes, Anne Phillips, Cyriel Y Ponsioen, Urõs Potocnik, Natalie J Prescott, Deborah D Proctor, Graham Radford-Smith, Jean-Francois Rahier, Soumya Raychaudhuri, Miguel Regueiro, Florian Rieder, John D Rioux, Stephan Ripke, Rebecca Roberts, Richard K Russell, Jeremy D Sanderson, Miquel Sans, Jack Satsangi, Eric E Schadt, Stefan Schreiber, Dominik Schulte, L Philip Schumm, Regan Scott, Mark Seielstad, Mark S Silverberg, Lisa A Simms, Jurgita Skieceviciene, Sarah L Spain, A. Hillary Steinhart, Joanne M Stempak, Laura Stronati, Jurgita Sventoraityte, Stephan R Targan, Kirstin M Taylor, Anje ter Velde, Emilie Theatre, Leif Torkvist, Mark Tremelling, Andrea van der Meulen, Suzanne van Sommeren, Eric Vasiliauskas, Severine Vermeire, Hein W Verspaget, Thomas Walters, Kai Wang, Ming-Hsi Wang, Rinse K Weersma, Zhi Wei, David Whiteman, Cisca Wijmenga, David C Wilson, Juliane Winkelmann, Ramnik J Xavier, Bin Zhang, Clarence K Zhang, Hu Zhang, Wei Zhang, Hongyu Zhao, Zhen Z Zhao.
Contributors MA, TH, DM and KSM conceived and designed the project. MA, SM, LT, DS, HH, TH and KSM carried out experiments and analysed the data. TH, DL, SD, GB, SY and MK developed computational methods and conducted data analysis. RM performed molecular in silico modeling of CFB. AP conducted PTM prediction search and interpretation. CL, EM and AW provided essential material and aided with the interpretation of the data. IIBDGC, ANA, WF, BJ, SAL, RDN, RS, RBS, RX, SB, JC, RHD, ML, JR, PS, MSS, KZ, PF, GM, EV, CH, SR, GS, NB, DZ, ML, SRT, DM and SY provided clinical samples and medical data. MA, TH, DM and KSM wrote the manuscript. TH, DM and KSM supervised the study. DM and KSM are guarantors of the paper.
Funding This work was supported by grants from the National Institute of Health (U01DK062413, P01 DK046763 to DM), the F. Widjaja Foundation (SRT, KSM), the Leona M. & Harry B. Helmsley Charitable Trust (DM) and the Fred L. Hartley Family Foundation (DM). This study was supported by the Cedars-Sinai MIRIAD IBD Biobank. The MIRIAD IBD Biobank is supported by the Widjaja Foundation Inflammatory Bowel and Immunobiology Research Institute, National Institute of Diabetes and Digestive and Kidney Disease Grants P01DK046763 and U01DK062413 and The Leona M. and Harry B. Helmsley Charitable Trust. We are grateful to all patients and control subjects that volunteered to join this study. The authors would like to thank the Cedars-Sinai Medical Center Flow Cytometry Core.
Competing interests Cedars-Sinai has financial interests in Prometheus Biosciences, a company which has access to the data and specimens in Cedars-Sinai’s MIRIAD Biobank (including the data and specimens used in this study) and seeks to develop commercial products. DM and SRT own stock in Prometheus Biosciences. DL, SRT and DM are consultants for Prometheus Biosciences. DM has consulted for Takeda, Sandoz Immunology, Gilead, Pfizer, Boehringer Ingelheim, Qu Biologics and Bridge Biotherapeutics. CH is on the Advisory Board or consultant for Abbvie, Bristol Myers Squibb, Ferring, Genentech, InDex Pharmaceuticals, Janssen, Pfizer, Takeda, received research support from Abbvie, Genentech, Eli Lilly, Pfizer, and educational grant funding from Pfizer. PF is a consultant for Takeda. GM is a consultant for Abbvie, Arena, Boehringer-Ingelheim, Bristol-Myers Squibb, Janssen, Medtronic, Techlab, Takeda, Pfizer, Samsung Bioepis, Entasis, Ferring, Shionogi and received research funding from Pfizer.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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