Direct role of plasma membrane-expressed gp120/41 in toxicity to human astrocytes induced by HIV-1-infected macrophages.
OBJECTIVE
To compare astrocyte toxicity induced by plasma membrane-expressed gp120/41 and soluble gp120.


METHODS
Analysis of morphological alterations and lactate dehydrogenase (LDH) release from astrocytes in culture with monocytes infected with HIV-1, microglia expressing Env of a macrophage-tropic HIV-1 isolate or soluble Env.


METHODS
Primary human embryonic astrocytes were cultured with: monocytes infected with two M-tropic HIV-1 isolates (HIV-1(9533), HIV-1(BX08)); human microglia infected with the defective Semliki Forest virus (SFV) vector coding for the env gene of HIV-1(BX08) isolate (SFVenvBX08); and soluble gp140 purified from baby hamster kidney cells transfected with the env gene of HIV-1(BX08) lacking the intracytoplasmic region of gp41 (SFVdelta envBX08). Gp120 mRNA levels were assessed by quantitative reverse transcriptase-polymerase chain reaction and the protein was detected by immunofluorescence in infected monocytes or microglia.


RESULTS
Contact of HIV-infected monocytes induced morphological changes in astrocytes and a 137% increase in LDH release at day 2 of co-culture compared with controls (uninfected monocytes). Gp120/41(BX08)-expressing microglia induced a 170% increase in LDH release (relative to SFVLacZ-infected microglia). Pretreatment of co-cultures with an anti-gp120 monoclonal antibody (mAb; NEA-9305) directed against the V3 loop inhibited LDH release. Soluble purified gp140 from BX08 isolate induced only a weak LDH release (104%). Finally, cytotoxicity was not blocked by treatment of the co-culture with Bordetella pertussis toxin, an inhibitor of Gi alpha protein-dependent receptors.


CONCLUSIONS
HIV envelope glycoprotein expressed at the plasma membrane induced astrocyte damage more efficiently than its soluble counterpart. The V3 loop was involved in toxicity induction through a pathway independent of the Gi alpha protein-coupled receptor.
Boutet
A
A
Laboratoire Virus, Neurone et Immunité, Université Paris-Sud, Le Kremlin-Bicêtre, France. agnes.boutet@kb.u-psud.fr
Altmeyer
R
R
Héry
C
C
Tardieu
M
M
D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D003588:Cytopathogenic Effect, Viral; D015699:HIV Envelope Protein gp120 / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism* / Q000633:toxicity; D015700:HIV Envelope Protein gp41 / Q000378:metabolism* / Q000633:toxicity; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000821:virology*; D017628:Microglia / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D009000:Monocytes / Q000166:cytology / Q000378:metabolism / Q000821:virology; D037342:Pertussis Toxin; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012672:Semliki forest virus / Q000235:genetics; D012995:Solubility; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D012367:RNA, Viral; D010566:Virulence Factors, Bordetella; D007770:L-Lactate Dehydrogenase; D037342:Pertussis Toxin