Unraveling proteoglycofili: a potential new neutrophil defense mechanism
ANDRÉ A. 1,2, VALENTE BARROSO M. 1, SKERNISKYTE J. 1, SIEGWALD M. 1, DEBANDE L. 1, PAUL V. 1, BROUSSAUDIER N. 1, THAHOULY T. 1, RIDLEY C. 3, SVAHN I. 4, BOWLER A. 5, RIGAUD S. 6, TINEVEZ J. 6, VIVÈS R. 7, SANSONETTI P. 2,8, RADTKE F. 5, THORNTON D. 3, MARTEYN B. 1,9,10
1 Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l’ARN, CNRS UPR9002, France, Strasbourg, France; 2 Institut Pasteur, Université Paris Cité, Inserm U1202, Unité Pathogénie Microbienne Moléculaire, France, Paris, France; 3 Wellcome Trust Centre for Cell-Matrix Research and the Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, The University of Manchester, UK, Manchester, United Kingdom; 4 University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UAR 3420, US 4, France, Bordeaux, France; 5 Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, Lausanne, Switzerland; 6 Institut Pasteur, Université Paris Cité, Image Analysis Hub, France, Paris, France; 7 Univ. Grenoble Alpes, CNRS, CEA, IBS, France, Grenoble, France; 8 Center for Microbes, Development and Health, Institut Pasteur of Shanghai and Chinese Academy of Sciences, China, Shanghai, China; 9 University of Strasbourg Institute for Advanced Study (USIAS), France, Strasbourg, France; 10 Institut Pasteur, Université de Paris, Inserm U1225, Unité de Pathogenèse des Infections Vasculaires, France, Paris, France
Neutrophils protect hosts from pathogens through various defense mechanisms such as degranulation and release of extracellular DNA traps (NETs). Our group recently discovered a potentially new defense mechanism of human neutrophils, consisting in the release of polymeric structures composed of granular proteins and glycosaminoglycans (GAGs), called proteoglycofili (PGF). After purification of human neutrophils under anoxic conditions, in addition to describing for the first time the secretion of GAGs by neutrophils, we showed that PGF can kill different bacteria, including S. flexneri 5a, and degrade their virulence factors. PGF are released by viable neutrophils and do not contain DNA, as opposed to NETs. We have also shown that the bacteria become covered by these GAGs, perhaps this being one way in which PGF is able to impair the pathogen growth. Through different methodologies such as RPIP-HPLC, ELISA, immunofluorescence, western blot and other techniques, we were able to show that the GAGs present in PGF are chondroitin sulfate (CS) and hyaluronic acid (HA), in addition to the presence of granular proteins such as lactoferrin, myeloperoxidase, elastase and cathelicidin. Furthermore, we also showed for the first time that GAGs enter into the composition of NETs, which are DNA traps decorated with granular proteins that have a high antimicrobial activity, and which are released in a death process called NETosis. Using specific enzymes as hyaluronidases, proteinase and DNAse, we have shown that the degradation of CS and HA, in addition to damaging the filamentous structure of PGF and NETs, also impairs their antimicrobial activity, proving that GAGs are essential for PGF antimicrobial activity. Our group also showed that PGF are present in vivo within Shigella infectious foci and in a murine colon cancer model, highlighting the potential clinical relevance of this new function of neutrophils.