title: PPARgamma and LXR signaling inhibit dendritic cell-mediated HIV-1 capture and trans-infection.
abstract: Dendritic cells (DCs) contribute to human immunodeficiency virus type 1 (HIV-1) transmission and dissemination by capturing and transporting infectious virus from the mucosa to draining lymph nodes, and transferring these virus particles to CD4+ T cells with high efficiency. Toll-like receptor (TLR)-induced maturation of DCs enhances their ability to mediate trans-infection of T cells and their ability to migrate from the site of infection. Because TLR-induced maturation can be inhibited by nuclear receptor (NR) signaling, we hypothesized that ligand-activated NRs could repress DC-mediated HIV-1 transmission and dissemination. Here, we show that ligands for peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor (LXR) prevented proinflammatory cytokine production by DCs and inhibited DC migration in response to the chemokine CCL21 by preventing the TLR-induced upregulation of CCR7. Importantly, PPARgamma and LXR signaling inhibited both immature and mature DC-mediated trans-infection by preventing the capture of HIV-1 by DCs independent of the viral envelope glycoprotein. PPARgamma and LXR signaling induced cholesterol efflux from DCs and led to a decrease in DC-associated cholesterol, which has previously been shown to be required for DC capture of HIV-1. Finally, both cholesterol repletion and the targeted knockdown of the cholesterol transport protein ATP-binding cassette A1 (ABCA1) restored the ability of NR ligand treated cells to capture HIV-1 and transfer it to T cells. Our results suggest that PPARgamma and LXR signaling up-regulate ABCA1-mediated cholesterol efflux from DCs and that this accounts for the decreased ability of DCs to capture HIV-1. The ability of NR ligands to repress DC mediated trans-infection, inflammation, and DC migration underscores their potential therapeutic value in inhibiting HIV-1 mucosal transmission.
authors.affiliation: Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Hanley
authors.forename: Wendy
authors.initials: W
authors.lastname: Blay Puryear
authors.forename: Suryaram
authors.initials: S
authors.lastname: Gummuluru
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Viglianti
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects; D054421:Chemokine CCL21 / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism; D003713:Dendritic Cells / Q000502:physiology / Q000821:virology*; D015658:HIV Infections / Q000635:transmission*; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors / Q000502:physiology*; D047495:PPAR gamma / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; C515478:CCL21 protein, human; D054421:Chemokine CCL21; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D047495:PPAR gamma; D018160:Receptors, Cytoplasmic and Nuclear; D002784:Cholesterol