Statin compounds reduce human immunodeficiency virus type 1 replication by preventing the interaction between virion-associated host intercellular adhesion molecule 1 and its natural cell surface ligand LFA-1

Abstract

A variety of host factors, including membrane proteins acquired by human immunodeficiency virus type 1 (HIV-1), play a dominant role in HIV-1 adsorption onto host cells. Examples include the integrin intercellular adhesion molecule 1 (ICAM-1), which, once acquired by HIV-1, promotes virus infectivity via ligation to LFA-1. We tested the ability of statins to diminish HIV-1 replication, based on the idea that these compounds have been shown to block ICAM-1-LFA-1 interactions. Our data indicate that statins diminish HIV-1 attachment to target cells by suppressing ICAM-1-LFA-1 interactions. The capacity of statins to limit the initial steps in virus replication could represent an interesting approach for the treatment of HIV-1 infection.

Figures

FIG. 1.

Statins decrease infection of LuSIV cells with ICAM-1-bearing virions but not with viruses lacking host ICAM-1. LuSIV reporter cells were first treated with lovastatin (A) or simvastatin (B) at the indicated concentrations at 37°C for 20 min. Next, target cells were inoculated with similar amounts of isogenic NL4-3 virus stocks either lacking (NL4-3) or bearing (NL4-3/ICAM-1) host-encoded ICAM-1 (10 ng of p24 for 105 cells). (C) An experimental strategy similar to that for panels A and B was used, except that cells were initially pretreated with the anti-LFA-1-activating antibody NKI-L16 for 30 min at 37°C (final concentration of 3 μg/ml) before the addition of lovastatin. Infection was allowed to proceed for 24 h before cells were lysed to monitor luciferase activity (MLX; Dynex Technologies, Chantilly, Va.). Luciferase activity is expressed in relative light units (RLU). Data shown represent the means ± standard deviations of results from triplicate samples, and these results are representative of three independent experiments. Luciferase activity values for mock-infected samples are shown on top of relevant bars.

FIG. 2.

Lovastatin efficiently abolishes replication and attachment of ICAM-1-bearing virions in primary human cells. (A) PBMCs were treated with lovastatin (50 μM) or the blocking anti-LFA-1 antibody MEM30 (1 μg/ml) for 20 min at 37°C before incubation for 2 h with viruses either lacking (NL4-3) or bearing (NL4-3/ICAM-1) host-encoded ICAM-1. Cells were extensively washed and resuspended in complete culture medium free of lovastatin or anti-LFA-1 antibody. Virus production was assessed with an in-house double-antibody sandwich enzyme-linked immunosorbent assay specific for the major viral p24 protein (3). (B) Pelleted cells were resuspended in lysis buffer (0.5% Triton X-100 in phosphate-buffered saline) to evaluate the amount of cell-associated viruses through p24 measurements. Data shown represent the means ± standard deviations of results from triplicate samples, and these results are representative of three independent experiments.

FIG. 3.

Replication of two clinical variants of HIV-1 in primary human cells is reduced by lovastatin. PBMCs were treated with lovastatin (50 μM) or the anti-LFA-1 antibody MEM30 (1 μg/ml) for 20 min at 37°C. Target cells were next exposed to the dual-tropic HIV-1 clinical isolates 92US151 (A) and 92RW009 (B). After several washes, cell pellets were resuspended in complete culture medium, and p24 levels were evaluated in the culture supernatant at days 2, 4, and 6 postinfection. Data shown represent the means ± standard deviations of results from triplicate samples, and these results are representative of three independent experiments.