title: Moraxella catarrhalis Evades Host Innate Immunity via Targeting Cartilage Oligomeric Matrix Protein.
abstract: Moraxella catarrhalis is a respiratory tract pathogen commonly causing otitis media in children and acute exacerbations in patients suffering from chronic obstructive pulmonary disease. Cartilage oligomeric matrix protein (COMP) functions as a structural component in cartilage, as well as a regulator of complement activity. Importantly, COMP is detected in resident macrophages and monocytes, alveolar fluid, and the endothelium of blood vessels in lung tissue. We show that the majority of clinical isolates of M. catarrhalis (n = 49), but not other tested bacterial pathogens, bind large amounts of COMP. COMP interacts directly with the ubiquitous surface protein A2 of M. catarrhalis. Binding of COMP correlates with survival of M. catarrhalis in human serum by inhibiting bactericidal activity of the complement membrane attack complex. Moreover, COMP inhibits phagocytic killing of M. catarrhalis by human neutrophils. We further observed that COMP reduces bacterial adhesion and uptake by human lung epithelial cells, thus protecting M. catarrhalis from intracellular killing by epithelial cells. Taken together, our findings uncover a novel mechanism that M. catarrhalis uses to evade host innate immunity.
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Guanghui
authors.identifier: http://orcid.org/0000-0001-8831-7739
authors.initials: G
authors.lastname: Liu
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Henrik
authors.initials: H
authors.lastname: Gradstedt
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: David
authors.identifier: http://orcid.org/0000-0003-4600-9070
authors.initials: D
authors.lastname: Ermert
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Emelie
authors.initials: E
authors.lastname: Englund
authors.affiliation: Division of Clinical Microbiology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Birendra
authors.identifier: http://orcid.org/0000-0002-7246-1442
authors.initials: B
authors.lastname: Singh
authors.affiliation: Division of Clinical Microbiology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Yu-Ching
authors.identifier: http://orcid.org/0000-0003-3398-6294
authors.initials: YC
authors.lastname: Su
authors.affiliation: Division of Pathology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden; and.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Johansson
authors.affiliation: Molecular Skeletal Biology, Department of Clinical Sciences, Biomedical Center, Lund University, SE-22 184 Lund, Sweden.
authors.forename: Anders
authors.identifier: http://orcid.org/0000-0002-6588-6944
authors.initials: A
authors.lastname: Aspberg
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Agarwal
authors.affiliation: Division of Clinical Microbiology, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden;
authors.forename: Kristian
authors.initials: K
authors.lastname: Riesbeck
authors.affiliation: Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, SE-205 02 Malmö, Sweden; Anna.Blom@med.lu.se.
authors.forename: Anna M
authors.identifier: http://orcid.org/0000-0002-1348-1734
authors.initials: AM
authors.lastname: Blom
mesh_terms: D001422:Bacterial Adhesion / Q000276:immunology; D064236:Cartilage Oligomeric Matrix Protein / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D005434:Flow Cytometry; D006801:Humans; D057131:Immune Evasion / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology*; D001936:Moraxella catarrhalis / Q000276:immunology* / Q000378:metabolism; D045828:Moraxellaceae Infections / Q000276:immunology* / Q000378:metabolism
chemical_list: D064236:Cartilage Oligomeric Matrix Protein