title: Fusion of HIV-1 envelope-expressing cells to human glomerular endothelial cells through an CXCR4-mediated mechanism.
abstract: A central question in the pathogenesis of HIV-associated thrombotic microangiopathic (HIV-TMA) lesions is whether the HIV-1 envelope glycoprotein (HIV-1 Env) can interact directly with human glomerular endothelial cells (HGECs) through specific HIV-1 co-receptors. The goal of this study was to determine whether cultured primary HGECs express significant levels of the major HIV-1 co-receptors CD4, CXCR4, and/or CCR5 to allow fusion interactions with HIV-1. The expression of CD4, CXCR-4 and CCR-5 was assessed in cultured HGECs by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry using specific antibodies. The HIV-1 Env-mediated membrane fusion of target glomerular cells was evaluated by a fluorescent dye transfer-based cell-cell fusion microscopic method. HGECs express CXCR4 mRNA and protein as determined by RT-PCR and immunostaining with phycoerythrin-conjugated anti-CXCR4 Mab 12G5. CD4 and CCR5 were not detected in HGECs, either by RT-PCR or by surface immunostaining with specific antibodies. Incubation of HGECs with cells expressing a CD4-independent envelope strain (HIV-1IIIB-8x) and the CD4-dependent envelope strain (HIV-1IIIB) resulted in transfer of fluorescent dyes of approximately 20% after 8-16 h incubation at 37 degrees C. Incubation in the presence of inhibitors (C34, which blocks six-helix bundle formation, and AMD3100, which interacts with CXCR4) reduced dye transfer by 60%-80%, confirming that the dye transfer was specific with respect to gp120-gp41-mediated fusion. Cultured primary HGECs express CXCR4 but not CD4 or CCR5. The ability of HGECs to promote fusion by a CD4-independent HIV-1 envelope glycoprotein suggests that these cells may become a potential direct target of certain HIV-1 isolates.
authors.affiliation: Division of Nephrology and Center for Genetic Medicine, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA. Pray@cnmc.org
authors.forename: Patricio E
authors.initials: PE
authors.lastname: Ray
authors.forename: Angel A
authors.initials: AA
authors.lastname: Soler-García
authors.forename: Lian
authors.initials: L
authors.lastname: Xu
authors.forename: Carl
authors.initials: C
authors.lastname: Soderland
authors.forename: Robert
authors.initials: R
authors.lastname: Blumenthal
authors.forename: Anu
authors.initials: A
authors.lastname: Puri
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism; D002468:Cell Physiological Phenomena; D002477:Cells / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007678:Kidney Glomerulus / Q000166:cytology / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D019713:Receptors, CCR5 / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000502:physiology*; D014759:Viral Envelope Proteins / Q000378:metabolism*
chemical_list: D015704:CD4 Antigens; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D014759:Viral Envelope Proteins