Structural basis for inhibition of coagulation factor VIII reveals a shared antigenic hotspot on the C1 domain.

Autor:	Childers KC; Chemistry Department, Western Washington University, Bellingham, Washington, USA., Cowper B; Medicines and Healthcare products Regulatory Agency, South Mimms Laboratories, Potters Bar, Hertfordshire, UK., Vaughan JD; Chemistry Department, Western Washington University, Bellingham, Washington, USA., McGill JR; Chemistry Department, Western Washington University, Bellingham, Washington, USA., Davulcu O; Pacific Northwest Center for Cryo-EM, Oregon Health & Science University, Portland, Oregon, USA; Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, Washington, USA., Lollar P; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, Georgia, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA., Doering CB; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, Georgia, USA; Department of Pediatrics, Emory University, Atlanta, Georgia, USA; Expression Therapeutics, Inc, Tucker, Georgia, USA., Coxon CH; Medicines and Healthcare products Regulatory Agency, South Mimms Laboratories, Potters Bar, Hertfordshire, UK., Spiegel PC Jr; Chemistry Department, Western Washington University, Bellingham, Washington, USA. Electronic address: paul.spiegel@wwu.edu.
Jazyk:	angličtina
Zdroj:	Journal of thrombosis and haemostasis : JTH [J Thromb Haemost] 2024 Sep; Vol. 22 (9), pp. 2449-2459. Date of Electronic Publication: 2024 Jun 05.
DOI:	10.1016/j.jtha.2024.05.024
Abstrakt:	Background: Hemophilia A arises from dysfunctional or deficient coagulation factor (F)VIII and leads to inefficient fibrin clot formation and uncontrolled bleeding events. The development of antibody inhibitors is a clinical complication in hemophilia A patients receiving FVIII replacement therapy. LE2E9 is an anti-C1 domain inhibitor previously isolated from a mild/moderate hemophilia A patient and disrupts FVIII interactions with von Willebrand factor and FIXa, though the intermolecular contacts that underpin LE2E9-mediated FVIII neutralization are undefined. Objectives: To determine the structure of the complex between FVIII and LE2E9 and characterize its mechanism of inhibition. Methods: FVIII was bound to the antigen binding fragment (Fab) of NB2E9, a recombinant construct of LE2E9, and its structure was determined by cryogenic electron microscopy. Results: This report communicates the 3.46 Å structure of FVIII bound to NB2E9, with its epitope comprising FVIII residues S2040 to Y2043, K2065 to W2070, and R2150 to H2155. Structural analysis reveals that the LE2E9 epitope overlaps with portions of the epitope for 2A9, a murine-derived inhibitor, suggesting that these residues represent a shared antigenic region on the C1 domain between FVIII -/- mice and hemophilia A patients. Furthermore, the FVIII:NB2E9 structure elucidates the orientation of the LE2E9 glycan, illustrating how the glycan sterically blocks interactions between the FVIII C1 domain and the von Willebrand factor D' domain. A putative model of the FVIIIa:FIXa complex suggests potential clashing between the NB2E9 glycan and FIXa light chain. Conclusion: These results describe an antigenic "hotspot" on the FVIII C1 domain and provide a structural basis for engineering FVIII replacement therapeutics with reduced antigenicity. Competing Interests: Declaration of competing interests P.L. is listed as an inventor on a patent application describing ET3i and on patents owned by Emory University claiming compositions of matter that include modified FVIII proteins with reduced reactivity with anti-FVIII antibodies. C.B.D. and P.L. are cofounders of Expression Therapeutics and own equity in the company. Expression Therapeutics owns the intellectual property associated with ET3i. The terms of this arrangement have been reviewed and approved by Emory University in accordance with its conflict-of-interest policies. The remaining authors have no competing interests to disclose. (Copyright © 2024 International Society on Thrombosis and Haemostasis. All rights reserved.)
Databáze:	MEDLINE
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