title: Time-controlled phagocytosis of asymmetric liposomes: Application to phosphatidylserine immunoliposomes binding HIV-1 virus-like particles.
abstract: Macrophage immune functions such as antibody-mediated phagocytosis are strongly impaired in individuals affected by HIV-1. Nevertheless, infected macrophages are still able to phagocytose apoptotic cells. For this reason, we recently developed antibody-decorated phosphatidylserine (PS)-containing liposomes that bind HIV-1 virus-like particles and, by mimicking apoptotic cells, are efficiently internalized by macrophages. In the context of an in vivo application, it would be extremely important to initially protect immunoliposomes from macrophages, in order to provide enough time to redistribute through the body and achieve maximum virus binding. To this end, we have designed asymmetric immunoliposomes in which the PS is initially confined to the inner leaflet and thus cannot be recognized by macrophages. Spontaneous PS flip-flop to the outer surface leads to a time-delay in internalization by macrophages in vitro. Such a delay can be fine-tuned by altering the molecular composition of the immunoliposomes.
  
  
  BACKGROUND
  In the fight against HIV-1, macrophage plays an important role. Ironically, the phagocytic functions of these cells are often impaired by HIV-1. In this interesting article, the authors described the development of asymmetric liposomes, which would bind HIV-1 with prolonged systemic circulation, such that the clearance of virus by macrophages is enhanced. This system represents a promising effective approach to utilize the phagocytic capability of macrophages.
authors.affiliation: Department of Biology/Molecular Biophysics, Humboldt Universität zu Berlin, Germany.
authors.forename: Roberto Arturo
authors.initials: RA
authors.lastname: Petazzi
authors.affiliation: Department of Biology/Molecular Biophysics, Humboldt Universität zu Berlin, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gramatica
authors.affiliation: Department of Biology/Molecular Biophysics, Humboldt Universität zu Berlin, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Department of Biology/Molecular Biophysics, Humboldt Universität zu Berlin, Germany. Electronic address: chiantia@gmail.com.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Chiantia
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D008081:Liposomes / Q000276:immunology*; D008264:Macrophages / Q000276:immunology / Q000821:virology*; D010587:Phagocytosis; D010718:Phosphatidylserines / Q000276:immunology*; D054299:env Gene Products, Human Immunodeficiency Virus / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D008081:Liposomes; D010718:Phosphatidylserines; D054299:env Gene Products, Human Immunodeficiency Virus
keywords: Asymmetric liposome; Flip-flop; HIV; Immunoliposome; Phosphatidylserine