HIV-1 gp120 Induces Expression of IL-6 through a Nuclear Factor-Kappa B-Dependent Mechanism: Suppression by gp120 Specific Small Interfering RNA

In addition to its role in virus entry, HIV-1 gp120 has also been implicated in HIV-associated neurocognitive disorders. However, the mechanism(s) responsible for gp120-mediated neuroinflammation remain undefined. In view of increased levels of IL-6 in HIV-positive individuals with neurological manifestations, we sought to address whether gp120 is involved in IL-6 over-expression in astrocytes. Transfection of a human astrocyte cell line with a plasmid encoding gp120 resulted in increased expression of IL-6 at the levels of mRNA and protein by 51.3±2.1 and 11.6±2.2 fold respectively; this effect of gp120 on IL-6 expression was also demonstrated using primary human fetal astrocytes. A similar effect on IL-6 expression was observed when primary astrocytes were treated with gp120 protein derived from different strains of X4 and R5 tropic HIV-1. The induction of IL-6 could be abrogated by use of gp120-specific siRNA. Furthermore, this study showed that the NF-κB pathway is involved in gp120-mediated IL-6 over-expression, as IKK-2 and IKKβ inhibitors inhibited IL-6 expression by 56.5% and 60.8%, respectively. These results were also confirmed through the use of NF-κB specific siRNA. We also showed that gp120 could increase the phosphorylation of IκBα. Furthermore, gp120 transfection in the SVGA cells increased translocation of NF-κB from cytoplasm to nucleus. These results demonstrate that HIV-1 gp120-mediated over-expression of IL-6 in astrocytes is one mechanism responsible for neuroinflammation in HIV-infected individuals and this is mediated by the NF-κB pathway

Human Immunodeficiency Virus Neurotropism: an Analysis of Viral Replication and Cytopathicity for Divergent Strains in Monocytes and Microglia

Productive replication of human immunodeficiency virus type 1 (HIV-1) in brain macrophages and microglia is a critical component of viral neuropathogenesis. However, how virus-macrophage interactions lead to neurological disease remains incompletely understood. Possibly, a differential ability of virus to replicate in brain tissue macrophages versus macrophages in other tissues underlies HIV-1 neurovirulence. To these ends, we established systems for the isolation and propagation of pure populations of human microglia and then analyzed the viral life cycles of divergent HIV-1 strains in these cells and in cultured monocytes by using identical viral inocula and indicator systems. The HIV-1 isolates included those isolated from blood, lung tissue, cerebrospinal fluids (CSF), and brain tissues of infected subjects: HIV-1(ADA) and HIV-1(89.6) (from peripheral blood mononuclear cells), HIV-1(DJV) and HIV-1(JR-FL) (from brain tissue), HIV-1(SF162) (from CSF), and HIV-1(BAL) (from lung tissue). The synthesis of viral nucleic acids and viral mRNA, cytopathicity, and release of progeny virions were assessed. A significant heterogeneity among macrophage-tropic isolates for infection of monocytes and microglia was demonstrated. Importantly, a complete analysis of the viral life cycle revealed no preferential differences in the abilities of the HIV-1 strains tested to replicate in microglia and/or monocytes. Macrophage tropism likely dictates the abilities of HIV-1 to invade, replicate, and incite disease within its microglial target cells

Evaluation of DFT Methods to Study Reactions of Benzene with OH Radical

Several density functional theory” (DFT) methods are applied to two different reaction channels involving OH• + C6H6, and the results compared with high-level ab initio calculations. The OH• adds directly to one C atom in the first channel, first forming an encounter complex with the OH• poised above the aromatic plane. B3LYP, BH&HLYP, and MPW1K compute an accurate estimate of the overall exothermicity, whereas M05-2X, PBE0, and PBEPBE overestimate this quantity to some degree. With the exceptions of PBEPBE and PBE0, the other methods produce an acceptable barrier to addition. All approaches except BH&HLYP correctly predict an exothermic H• abstraction, although PBEPBE is too exothermic. The BH&HLYP barrier to H• abstraction is too high while the MPW1K, PBE0, and B3LYP values are better, and M05-2X the best