HIV-1 Tat-mediated apoptosis in human brain microvascular endothelial cells.
The integrity of the blood-brain barrier (BBB) is critical for normal brain function. Neuropathological abnormalities in AIDS patients have been associated with perivascular HIV-infected macrophages, gliosis, and abnormalities in the permeability of the BBB. The processes by which HIV causes these pathological conditions are not well understood. To characterize the mechanism by which HIV-1 Tat protein modulates human brain microvascular endothelial cell (HBMEC) functions, we studied the effects of HIV-1 Tat in modulating HBMEC apoptosis and permeability. Treatment of HBMEC with HIV-1 Tat led to Flk-1/KDR and Flt-4 receptor activation and the release of NO. The protein levels of endothelial NO synthase (NOS) and inducible NOS were increased by HIV-1 Tat stimulation. Importantly, HIV-1 Tat caused apoptosis of HBMEC, as evidenced by changes in the cleavage of poly(A)DP-ribose polymerase, DNA laddering, and incorporation of fluorescein into the nicked chromosomal DNA (TUNEL assay). HIV-1 Tat-mediated apoptosis in HBMEC was significantly inhibited in the presence of N-nitro-L-arginine methyl ester (an inhibitor of NOS) and wortmannin (a phosphoinositol 3-kinase inhibitor). Furthermore, HIV-1 Tat treatment significantly increased HBMEC permeability, and pretreatment with both N-nitro-L-arginine methyl ester and wortmannin inhibited the Tat-induced permeability. Taken together, these results indicate that dysregulated production of NO by HIV-1 Tat plays a pivotal role in brain endothelial injury, resulting in the irreversible loss of BBB integrity, which may lead to enhanced infiltration of virus-carrying cells across the BBB.
Kim
Tae-Aug
TA
Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Avraham
Hava Karsenty
HK
Koh
Young-Ho
YH
Jiang
Shuxian
S
Park
In-Woo
IW
Avraham
Shalom
S
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D053938:DNA Fragmentation / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology* / Q000821:virology*; D015696:Gene Products, tat / Q000494:pharmacology / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008833:Microcirculation / Q000166:cytology / Q000378:metabolism / Q000502:physiology / Q000821:virology; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D011994:Recombinant Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D040301:Vascular Endothelial Growth Factor Receptor-2; D040321:Vascular Endothelial Growth Factor Receptor-3