title: Production of interferon α by human immunodeficiency virus type 1 in human plasmacytoid dendritic cells is dependent on induction of autophagy.
abstract: BACKGROUND
  The mechanisms responsible for interferon α (IFN-α) production by plasmacytoid dendritic cells (pDCs) during human immunodeficiency virus type 1 (HIV-1) infection are unknown. This research examined the roles of Toll-like receptor 7 (TLR7) and autophagy in IFN-α production by pDCs during HIV-1 infection.
  
  
  METHODS
  pDCs from human peripheral blood mononuclear cells were incubated with infectious or aldrithiol 2 (AT-2)-inactivated HIV-1 or with uridine-rich single-stranded RNA40 (ssRNA40) from the HIV-1 long terminal repeat. IFN-α was quantified by enzyme-linked immunosorbant assay. Autophagic proteins were detected by Western blot, and autophagosomes were identified using immunofluorescent and confocal microscopy. To inhibit autophagy, pDCs were treated with the phosphoinositide-3 kinase inhibitor 3-methyladenine (3-MA) or were transfected with autophagy-related protein 7 or TLR7 small interfering RNA (siRNA).
  
  
  RESULTS
  Increased levels of IFN-α were present in culture supernatants following 16-hour incubation of pDCs with infectious or AT-2-inactivated HIV-1. Treatment of pDCs with ssRNA40 but not ssRNA41 resulted in high levels of IFN-α. pDCs exposed to HIV-1 gp120, rapamycin, or 3-MA alone failed to induce IFN-α. Pretreatment of pDCs with 3-MA significantly reduced the induction of IFN-α by ssRNA40. Similarly, knock down of autophagy-related protein 7 and TLR7 by use of siRNA significantly reduced the induction of IFN-α by ssRNA40 or HIV-1.
  
  
  CONCLUSIONS
  These findings demonstrate that IFN-α production by pDCs exposed to infectious or noninfectious HIV-1 and ssRNA40 occurs through induction of autophagy following TLR7 signaling.
authors.affiliation: Department of Pediatrics, Division of Infectious Diseases, University of California-San Diego, La Jolla, CA, USA.
authors.forename: Dejiang
authors.initials: D
authors.lastname: Zhou
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Kang
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Spector
mesh_terms: D001343:Autophagy / Q000502:physiology*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000378:metabolism* / Q000821:virology*; D005786:Gene Expression Regulation; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D050839:Interferon Regulatory Factor-7 / Q000235:genetics / Q000378:metabolism; D016898:Interferon-alpha / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D051199:Toll-Like Receptor 7 / Q000235:genetics / Q000378:metabolism
chemical_list: D007166:Immunosuppressive Agents; D050839:Interferon Regulatory Factor-7; D016898:Interferon-alpha; D034741:RNA, Small Interfering; C495348:TLR7 protein, human; D051199:Toll-Like Receptor 7; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus