Complement lectin pathway components MBL and MASP-1 promote haemostasis upon vessel injury in a microvascular bleeding model

• Type of Material: Article
• Authors: Murielle Golomingi, University of Bern; Jessie Kohler, University of Bern; Lorenz Jenny, University of Bern; Elaissa Hardy, Emory University; József Dobó, Research Centre for Natural Sciences, Budapest, Hungary; Péter Gál, Research Centre for Natural Sciences, Budapest, Hungary; Gábor Pál, Eötvös Loránd University; Bence Kiss, Eötvös Loránd University; Wilbur Lam, Emory University; Verena Schroeder, University of Bern
• Language: English
• Date: 2022-08-12
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2022 Golomingi, Kohler, Jenny, Hardy, Dobó, Gál, Pál, Kiss, Lam and Schroeder
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fimmu.2022.948190
• Title of Journal or Parent Work: FRONTIERS IN IMMUNOLOGY
• Volume: 13
• Start Page: 948190
• End Page: 948190
• Grant/Funding Information: This project was funded by grants awarded to VS by the Swiss National Science Foundation, grant number 310030_166413 (Bern, Switzerland), OPO Foundation (Zurich, Switzerland), Novartis Foundation for Medical-Biological Research (Basel, Switzerland), and Gottfried & Julia Bangerter-Rhyner Foundation (Bern, Switzerland).; Other grant contributions to GP and PG were provided by project no. 2018-1.2.1-NKP-2018-00005 implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the 2018-1.2.1-NKP funding scheme and by the National Research, Development and Innovation Office (Hungarian Scientific Research Fund) grants K119374, K119386, KH130376 and K135289.
• Keywords: mannan-binding lectin (MBL); Life Sciences & Biomedicine; Immunology; SERINE PROTEASE-1; complement system; Science & Technology; MBL-associated serine protease-1 (MASP-1); haemostasis; ACTIVATION; SYSTEM; GENERATION; INHIBITORS; COAGULATION; microfluidics; MEROPS

Abstract

Background: Complement lectin pathway components, in particular mannan-binding lectin (MBL) and MBL-associated serine proteases (MASPs) have been shown to interact with coagulation factors and contribute to clot formation. Here we investigated the role of MBL and MASP-1 in the haemostatic response following mechanical vessel injury in a human microfluidic bleeding model. Methods: We studied haemostasis in a microvascular bleeding model in the presence of human endothelial cells and human whole blood under flow conditions. We monitored incorporation of proteins into the clot with fluorescently labelled antibodies and studied their effects on clot formation, platelet activation, and bleeding time with specific inhibitors. Platelet activation was also studied by flow cytometry. Results: Upon vessel injury, MBL accumulated at the injury site in a well-defined wall-like structure. MBL showed partial colocalisation with fibrin, and strong colocalisation with von Willebrand factor and (activated) platelets. Flow cytometry ruled out direct binding of MBL to platelets, but confirmed a PAR4- and thrombin-dependent platelet-activating function of MASP-1. Inhibiting MBL during haemostasis reduced platelet activation, while inhibiting MASP-1 reduced platelet activation, fibrin deposition and prolonged bleeding time. Conclusion: We show in a microvascular human bleeding model that MBL and MASP-1 have important roles in the haemostatic response triggered by mechanical vessel injury: MBL recognises the injury site, while MASP-1 increases fibrin formation, platelet activation and shortens bleeding time. While the complement lectin pathway may be harmful in the context of pathological thrombosis, it appears to be beneficial during the physiological coagulation response by supporting the crucial haemostatic system.