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A more recent version of this article appeared on October 1, 2005

Published online before print August 4, 2005
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© by The Society for Leukocyte Biology
Journal of Leukocyte Biology, doi:10.1189/jlb.0105056

Received for publication January 31, 2005.
Revised May 4, 2005.
Accepted for publication May 5, 2005.

Article

HIV-1 gp120-induced TNF-{alpha} production by primary human macrophages is mediated by phosphatidylinositol-3 (PI-3) kinase and mitogen-activated protein (MAP) kinase pathways

Chuhee Lee *, Brian Tomkowicz *, Bruce D. Freedman {dagger}, and Ronald G. Collman *@

Departments of *Medicine, University of Pennsylvania School of Medicine, and {dagger}Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia

@ To whom correspondence should be addressed. E-mail: collmanr{at}mail.med.upenn.edu.


  Abstract

Human immunodeficiency virus type 1 (HIV-1) infection is initiated by binding of the viral envelope glycoprotein gp120 to CD4 followed by a chemokine receptor, but these interactions may also take place independently from infection. gp120 stimulation of primary human macrophages is known to trigger production of cytokines implicated in pathogenesis, particularly tumor necrosis factor {alpha} (TNF-{alpha}), but the mechanisms have not been determined. We sought to define the pathways responsible for TNF-{alpha} secretion by monocyte-derived macrophages (MDM) following HIV-1 gp120 stimulation. MDM exposure to recombinant macrophage-tropic (R5) gp120 led to dose- and donor-dependent release of TNF-{alpha}, which was cyclohexamide-sensitive and associated with up-regulated message. Pretreatment with specific inhibitors of the mitogen-activated protein kinases (MAPK) extracellular signal-regulated kinase 1/2 (ERK-1/2; PD98059, U0126) and p38 (SB202190, PD169316) inhibited the secretion of TNF-{alpha}. gp120-elicited TNF-{alpha} production was also blocked by phosphatidylinositol-3 kinase (PI-3K) inhibitors (wortmannin, LY294002). Moreover, PI-3K inhibition ablated gp120-induced phosphorylation of p38 and ERK-1/2. The response was inhibited by a CC chemokine receptor 5 (CCR5)-specific antagonist, indicating that CCR5 was in large part responsible. These results indicate that gp120-elicited TNF-{alpha} production by macrophages involves chemokine receptor-mediated PI-3K and MAPK activation, that PI-3K is an upstream regulator of MAPK in this pathway, and that p38 and ERK-1/2 independently regulate TNF-{alpha} production. These gp120-triggered signaling pathways may be responsible for inappropriate production of proinflammatory cytokines by macrophages, which are believed to play a role in immunopathogenesis and in neurological sequelae of AIDS.

Key Words: monocyte • AIDS • signal transduction • HIV-associated dementia






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