title: Molecular organization of the non-bilayer phospholipid arrangements that induce an autoimmune disease resembling human lupus in mice.
abstract: Non-bilayer phospholipid arrangements are three-dimensional structures that can form when anionic phospholipids with an intermediate form of the tubular hexagonal phase II (H(II)), such as phosphatidic acid, phosphatidylserine or cardiolipin, are present in a bilayer of lipids. The drugs chlorpromazine and procainamide, which trigger a lupus-like disease in humans, can induce the formation of non-bilayer phospholipid arrangements, and we have previously shown that liposomes with non-bilayer arrangements induced by these drugs cause an autoimmune disease resembling human lupus in mice. Here we show that liposomes with non-bilayer phospholipid arrangements induced by Mn²⁺ cause a similar disease in mice. We extensively characterize the physical properties and immunological reactivity of liposomes made of the zwitterionic lipid phosphatidylcholine and a H(II)-preferring lipid, in the absence or presence of Mn²⁺, chlorpromazine or procainamide. We use an hapten inhibition assay to define the epitope recognized by sera of mice with the disease, and by a monoclonal antibody that binds specifically to non-bilayer phospholipid arrangements, and we report that phosphorylcholine and glycerolphosphorylcholine, which form part of the polar region of phosphatidylcholine, are the only haptens that block the binding of the tested antibodies to non-bilayer arrangements. We propose a model in which the negatively charged H(II)-preferring lipids form an inverted micelle by electrostatic interactions with the positive charge of Mn²⁺, chlorpromazine or procainamide; the inverted micelle is inserted into the bilayer of phosphatidylcholine, whose polar regions are exposed and become targets for antibody production. This model may be relevant in the pathogenesis of human lupus.
authors.affiliation: Biochemistry Department, National School of Biological Sciences, National Polytechnic Institute (IPN), Mexico City, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Wong-Baeza
authors.forename: Rogelio
authors.initials: R
authors.lastname: Hernández-Pando
authors.forename: Albany
authors.initials: A
authors.lastname: Reséndiz
authors.forename: Alonso
authors.initials: A
authors.lastname: Tescucano
authors.forename: Israel
authors.initials: I
authors.lastname: Bustos
authors.forename: Miguel
authors.initials: M
authors.lastname: Ibáñez
authors.forename: Carlos
authors.initials: C
authors.lastname: Wong
authors.forename: Isabel
authors.initials: I
authors.lastname: Baeza
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002308:Cardiolipins / Q000737:chemistry / Q000276:immunology; D002417:Cattle; D002746:Chlorpromazine / Q000633:toxicity; D007678:Kidney Glomerulus / Q000473:pathology; D008180:Lupus Erythematosus, Systemic / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008345:Manganese / Q000633:toxicity; D051379:Mice; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010712:Phosphatidic Acids / Q000737:chemistry / Q000276:immunology; D010713:Phosphatidylcholines / Q000737:chemistry / Q000276:immunology; D010718:Phosphatidylserines / Q000737:chemistry / Q000276:immunology; D011342:Procainamide / Q000633:toxicity; D012867:Skin / Q000473:pathology; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D002308:Cardiolipins; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D053835:Unilamellar Liposomes; D008345:Manganese; D011342:Procainamide; D002746:Chlorpromazine