Development of a human neuronal cell model for human immunodeficiency virus (HIV)-infected macrophage-induced neurotoxicity: apoptosis induced by HIV type 1 primary isolates and evidence for involvement of the Bcl-2/Bcl-xL-sensitive intrinsic apoptosis pathway.
Neuronal apoptosis within the central nervous system (CNS) is a characteristic feature of AIDS dementia, and it represents a common mechanism of neuronal death induced by neurotoxins (e.g., glutamate) released from human immunodeficiency virus (HIV)-infected macrophages (HIV/macrophage-induced neurotoxicity). Neuronal apoptosis may result from activation of the intrinsic (mitochondrial/bcl-2 regulated) or extrinsic (death receptor) pathways, although which pathway predominates in CNS HIV infection is unknown. Apoptosis initiated by the intrinsic pathway is typically blocked by antiapoptosis Bcl-2 family proteins, such as Bcl-2 and Bcl-xL, but whether these can block HIV/macrophage-induced neuronal apoptosis is unknown. To determine the potential role of the Bcl-2 family in HIV/macrophage-induced neuronal apoptosis, we developed a unique in vitro model, utilizing the NT2 neuronal cell line, primary astrocytes and macrophages, and primary CNS HIV type 1 (HIV-1) isolates. We validated our model by demonstrating that NT2.N neurons are protected against HIV-infected macrophages by N-methyl-D-aspartate (NMDA) glutamate receptor antagonists, similar to effects seen in primary neurons. We then established stable NT2.N neuronal lines that overexpress Bcl-2 or Bcl-xL (NT2.N/bcl-2 and NT2.N/bcl-xL, respectively) and determined their sensitivity to macrophages infected with primary R5, X4, and R5/X4 HIV-1 isolates. We found that NT2.N/bcl-2 and NT2.N/bcl-xL neurons were resistant to apoptosis induced by either R5, X4, or R5/X4 isolates and that resistance was abrogated by a Bcl-2 antagonist. Thus, the NMDA receptor/bcl-2-regulated apoptotic pathway contributes significantly to HIV/macrophage-induced neuronal apoptosis, and Bcl-2 family proteins protect neurons against the spectrum of primary HIV-1 isolates. Modulation of bcl-2 gene expression may therefore offer adjunctive neuroprotection against development of AIDS dementia.
Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
Wei
W
Chen
Jerrold
J
Sulcove
Ian
I
Frank
Salman
S
Jaffer
Hakan
H
Ozdener
Dennis L
DL
Kolson
D015526:AIDS Dementia Complex / Q000473:pathology / Q000821:virology; D017209:Apoptosis; D001253:Astrocytes / Q000473:pathology / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008264:Macrophages / Q000821:virology*; D009000:Monocytes / Q000821:virology; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D016194:Receptors, N-Methyl-D-Aspartate; D051020:bcl-X Protein