title: Toll-like receptor 2 promiscuity is responsible for the immunostimulatory activity of nucleic acid nanocarriers.
abstract: Lipopolyamines (LPAs) are cationic lipids; they interact spontaneously with nucleic acids to form lipoplexes used for gene delivery. The main hurdle to using lipoplexes in gene therapy lies in their immunostimulatory properties, so far attributed to the nucleic acid cargo, while cationic lipids were considered as inert to the immune system. Here we demonstrate for the first time that di-C18 LPAs trigger pro-inflammatory responses through Toll-like receptor 2 (TLR2) activation, and this whether they are bound to nucleic acids or not. Molecular docking experiments suggest potential TLR2 binding modes reminiscent of bacterial lipopeptide sensing. The di-C18 LPAs share the ability of burying their lipid chains in the hydrophobic cavity of TLR2 and, in some cases, TLR1, at the vicinity of the dimerization interface; the cationic headgroups form multiple hydrogen bonds, thus crosslinking TLRs into functional complexes. Unravelling the molecular basis of TLR1 and TLR6-driven heterodimerization upon LPA binding underlines the highly collaborative and promiscuous ligand binding mechanism. The prevalence of non-specific main chain-mediated interactions demonstrates that potentially any saturated LPA currently used or proposed as transfection agent is likely to activate TLR2 during transfection. Hence our study emphasizes the urgent need to test the inflammatory properties of transfection agents and proposes the use of docking analysis as a preliminary screening tool for the synthesis of new non-immunostimulatory nanocarriers.
authors.affiliation: Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium. Electronic address: malvina.pizzuto@gmail.com.
authors.forename: Malvina
authors.initials: M
authors.lastname: Pizzuto
authors.affiliation: Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, UK. Electronic address: mg308@cam.ac.uk.
authors.forename: Monique
authors.initials: M
authors.lastname: Gangloff
authors.affiliation: CNRS, Unité de Technologies Chimiques et Biologiques pour la Santé (UTCBS), UMR 8258, F-75006 Paris, France; INSERM, UTCBS U 1022, F-75006 Paris, France; Université Paris Descartes, Sorbonne-Paris-Cité University, UTCBS, F-75006 Paris, France; Chimie ParisTech, PSL Research University, UTCBS, F-75005 Paris, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Scherman
authors.affiliation: Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Gay
authors.affiliation: CNRS, Unité de Technologies Chimiques et Biologiques pour la Santé (UTCBS), UMR 8258, F-75006 Paris, France; INSERM, UTCBS U 1022, F-75006 Paris, France; Université Paris Descartes, Sorbonne-Paris-Cité University, UTCBS, F-75006 Paris, France; Chimie ParisTech, PSL Research University, UTCBS, F-75005 Paris, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Escriou
authors.affiliation: Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Ruysschaert
authors.affiliation: Structure and Function of Biological Membranes, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium; Department of Veterinary Medicine, University of Cambridge, Madingley Rd, Cambridge CB3 0ES, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lonez
mesh_terms: D002460:Cell Line; D057809:HEK293 Cells; D006801:Humans; D007249:Inflammation / Q000139:chemically induced* / Q000276:immunology; D008055:Lipids / Q000009:adverse effects / Q000276:immunology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D062105:Molecular Docking Simulation; D009696:Nucleic Acids / Q000008:administration & dosage / Q000235:genetics; D011073:Polyamines / Q000009:adverse effects / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000276:immunology*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D008055:Lipids; D009696:Nucleic Acids; D011073:Polyamines; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha
keywords: Docking; Gene therapy; Lipoplex; Lipopolyamine (LPA); Nanocarrier; Toll-like receptor (TLR)