HIV-1 Tat is considered to be one of key players to facilitate monocyte entry into the CNS, which is characteristic feature of AIDS-related encephalitis and dementia. This study was performed to determine the regulatory function of superoxide dismutase (SOD) on the HIV-1 Tat-induced signaling pathways leading to NF-kappaB activation, expression of adhesion molecules, and monocyte adhesion in CRT-MG human astroglioma cells by using cell-permeable SOD. When cell-permeable SOD was added to the culture medium of CRT-MG cells, it rapidly entered the cells in dose- and time-dependent manners. Treatment of astrocytes with cell-permeable SOD led to decrease in Tat-induced ROS generation as well as NF-kappaB activation. Cell-permeable SOD inhibited the activation of MAP kinases including ERK, JNK and p38 by HIV-1 Tat. Treatment of CRT-MG cells with cell-permeable SOD significantly inhibited protein and mRNA levels of ICAM-1 and VCAM-1 up-regulated by HIV-1 Tat, as measured by Western blot analysis and RT-PCR. Furthermore, enhanced adhesiveness of monocyte to astrocyte by HIV-1 Tat was significantly abrogated by pretreatment with cell-permeable SOD fusion proteins. These data indicate that SOD has a regulatory function for HIV-1 Tat-induced NF-kappaB activation in astrocytes and suggest that cell-permeable SOD can be used as a feasible therapeutic agent for regulation of ROS-related neurological diseases.
Astrocytes/*enzymology ; Cell Adhesion/*physiology ; Cell Membrane Permeability ; Gene Products, tat/*pharmacology ; HIV Infections/metabolism ; HIV-1/*chemistry ; Humans ; Monocytes/cytology/*drug effects ; Signal Transduction ; Superoxide Dismutase/genetics/*physiology

The infiltration of monocytes into the CNS represents one of the early steps to inflammatory events in AIDS-related encephalitis and dementia. Increased activity of selected matrix metalloproteinases (MMPs) such as MMP-9 impairs the integrity of blood-brain barrier leading to enhanced monocyte infiltration into the CNS. In this study, we examined the effect of HIV-1 Tat on the expression of MMP-9 in CRT-MG human astroglioma cells. Treatment of CRT-MG cells with HIV-1 Tat protein significantly increased protein levels of MMP-9, as measured by Western blot analysis, zymography and an ELISA. Treatment of CRT-MG cells with HIV-1 Tat protein markedly increased mRNA levels of MMP-9, as analyzed by RT-PCR. Pretreatment of CRT-MG cells with NF-kappaB inhibitors led to decrease in Tat-induced protein and mRNA expression of MMP-9. Pretreatment of CRT-MG cells with MAPK inhibitors suppressed Tat-induced MMP-9 expression. Furthermore, HIV-1 Tat-induced expression of MMP-9 was significantly inhibited by neutralization of TNF-alpha, but not IL-1beta and IL-6. Taken together, our results indicate that HIV-1 Tat can up-regulate expression of MMP-9 via MAPK-NF-kappaB-dependent mechanisms as well as Tat-induced TNF-alpha production in astrocytes.
AIDS Dementia Complex/*metabolism ; Astrocytes/*drug effects/enzymology ; HIV Infections/*complications ; *HIV-1 ; Humans ; Matrix Metalloproteinase 9/*genetics/immunology ; Mitogen-Activated Protein Kinase Kinases/*metabolism ; NF-kappa B/*metabolism ; Tumor Cells, Cultured ; Tumor Necrosis Factor-alpha/immunology/metabolism ; Up-Regulation/drug effects ; tat Gene Products, Human Immunodeficiency Virus/*metabolism

OBJECTIVETo investigate whether two kinds of in vitro prepared advanced glycation end products (AGEs), Glu-BSA and Gal-BSA, could change oxidation stress and anti-oxidation abilities in astrocytes, and thus might contribute to brain injury.

METHODSChanges of GSH, MDA, SOD, MAO-B, nitric oxide were measured after AGEs treatment.

RESULTSBoth 0.1 g/L Glu-BSA and Gal-BSA could slightly decrease GSH level, while 1 g/L of them significantly decreased GSH level by 35% and 43% respectively. The MDA levels of both 1 g/L AGEs treated groups (306 +/- 13 and 346 +/- 22) were higher than that of the normal group (189 +/- 18), which could be inhibited by free radical scavenger NAC. The SOD activities of both 1 g/L AGEs treated groups (67.0 +/- 5.2 and 74.0 +/- 11.0) were lower than that of the normal group (85.2 +/- 8.0). Both 0.1 g/L AGEs could slightly increase the activity of MAO-B, while 1 g/L of them could increase MAO-B activity by 1.5 and 1.7 folds respectively. Both AGEs stimulation could produce NO level by 1.7 and 2 folds respectively.

CONCLUSIONEnhanced levels of astrocytic oxidation stress and decrease of antioxidation abilities may contribute to, at least partially, the detrimental effects of AGEs in neuronal disorders and aging brain.

Animals ; Astrocytes ; drug effects ; enzymology ; metabolism ; Cattle ; Cells, Cultured ; Cerebral Cortex ; cytology ; Glutathione ; metabolism ; Glycation End Products, Advanced ; pharmacology ; Malondialdehyde ; metabolism ; Monoamine Oxidase ; metabolism ; Nitric Oxide ; metabolism ; Oxidative Stress ; drug effects ; Rats ; Rats, Wistar ; Serum Albumin, Bovine ; pharmacology ; Superoxide Dismutase ; metabolism