title: Microglial activation decreases retention of the protease inhibitor saquinavir: implications for HIV treatment.
abstract: BACKGROUND
  Active HIV infection within the central nervous system (CNS) is confined primarily to microglia. The glial cell compartment acts as a viral reservoir behind the blood-brain barrier. It provides an additional roadblock to effective pharmacological treatment via expression of multiple drug efflux transporters, including P-glycoprotein. HIV/AIDS patients frequently suffer bacterial and viral co-infections, leading to deregulation of glial cell function and release of pro-inflammatory mediators including cytokines, chemokines, and nitric oxide.
  
  
  METHODS
  To better define the role of inflammation in decreased HIV drug accumulation into CNS targets, accumulation of the antiretroviral saquinavir was examined in purified cultures of rodent microglia exposed to the prototypical inflammatory mediator lipopolysaccharide (LPS).
  
  
  RESULTS
  [(3)H]-Saquinavir accumulation by microglia was rapid, and was increased up to two-fold in the presence of the specific P-glycoprotein inhibitor, PSC833. After six or 24 hours of exposure to 10 ng/ml LPS, saquinavir accumulation was decreased by up to 45%. LPS did not directly inhibit saquinavir transport, and did not affect P-glycoprotein protein expression. LPS exposure did not alter RNA and/or protein expression of other transporters including multidrug resistance-associated protein 1 and several solute carrier uptake transporters.
  
  
  CONCLUSIONS
  The decrease in saquinavir accumulation in microglia following treatment with LPS is likely multi-factorial, since drug accumulation was attenuated by inhibitors of NF-κβ and the MEK1/2 pathway in the microglia cell line HAPI, and in primary microglia cultures from toll-like receptor 4 deficient mice. These data provide new pharmacological insights into why microglia act as a difficult-to-treat viral sanctuary site.
authors: National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA. sdallas@its.jnj.com
authors: Shannon
authors: S
authors: Dallas
authors: Michelle L
authors: ML
authors: Block
authors: Deborah M
authors: DM
authors: Thompson
authors: Marcelo G
authors: MG
authors: Bonini
authors: Patrick T
authors: PT
authors: Ronaldson
authors: Reina
authors: R
authors: Bendayan
authors: David S
authors: DS
authors: Miller
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003627:Data Interpretation, Statistical; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D017320:HIV Protease Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects*; D017628:Microglia / Q000502:physiology*; D009573:Nitrites / Q000378:metabolism; D011247:Pregnancy; D061251:Primary Cell Culture; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D019258:Saquinavir / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D017320:HIV Protease Inhibitors; D008070:Lipopolysaccharides; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D019258:Saquinavir
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