Doses Of Gp120 Research Articles

965. Antioxidant Enzyme Protection from HIV-1 gp120-Induced Neuronal Apoptosis by Gene Delivery Using rSV40 Vectors: Implication for Gene Therapy of AIDS

Human immunodeficiency virus-1 (HIV-1) infection causes neuronal toxicity and oxidative injury: HIV-1 gene products, especially gp120, induce free radical-mediated apoptosis. Nitric oxide (NO), when present in high concentrations, is a potential mediator of neuronal injury via upregulation of inducible nitric oxide synthase (iNOS) and formation of reactive oxygen species (ROS).We thus tested whether rSV40 gene delivery to central nervous system (CNS) can be exploited to protect the brain and mitigate HIV encephalopathy. We hypothesized that neurons, which readily form ROS as a result of HIV-1/gp120 exposure, could be protected using rSV40 viruses encoding Cu/Zn-superoxide dismutase (SOD1) and/or glutathione peroxidase (GPX1). Both of these enzymes detoxify oxygen free radical species. Our test system was cultured mature neurons derived from NT-2 cells. These were transduced with rSV40 vectors carrying SOD1 or GPX1, or control rSV40 vectors, and challenged by adding HIV-1 gp120. Apoptosis was measured by TUNEL assay. Transduction with SV(SOD1) and SV(GPX1) provided excellent transgene expression when tested in terminally differentiated NT-2 neurons, as assessed by western blotting, kinetic assays of enzyme activity and immunostaining. Transduction efficiency by the recombinant SV40 delivered vectors exceeded 95% as assayed by immunostaining. When used on NT2 derived neurons, gp120, induced apoptosis with a linear dose response relationship with an optimal concentration of 100 ng/ml (0.9 nm) for induction of apoptosis. SV(SOD1) and SV(GPX1) transduced cells, when challenged with this dose of gp120, were protected up to >90% from apoptosis, as tested using TUNEL assay. Protection was dose dependent: suboptimal transducing doses of these vectors protected less well. Combination transduction with both viruses (SOD1 and GPX1), showed >95% protection against gp120 apoptosis. We therefore demonstrate the effectiveness of SOD1 and GPX1 delivered by SV40 vectors, either singly or in combination, to protect neuronal cells susceptible to HIV-1. These findings may help to address issues related to gene delivery to the central nervous system and gene therapy to protect from the encephalopathy that attends HIV-1 infection in brain.

Mechanisms of HIV type 1-induced cognitive impairment: evidence for hippocampal cholinergic involvement with overstimulation of the VIPergic system by the viral coat protein core.

HIV-1 is associated with a neuroAIDS syndrome that includes cognitive impairment. Several components of HIV-1 are capable of affecting cognition, but which of these is the major mediator is unknown. We injected into the lateral cerebral ventricle of mice HIV-1 pseudoviruses expressing the full viral genome with or without the viral coat glycoproteins, gp120/gp41. Only virus possessing gp120/gp41 induced defects in memory as assessed in an active avoidance T-maze footshock paradigm. By itself, gp120 also induced impairments that were reversed by hippocampal cholinergic stimulation. Paradoxically, low doses of gp120 could improve memory. Such low-dose, paradoxic improvement is a characteristic of substances that impair memory by overstimulating pathways that normally sustain memory. Consistent with this, a low, but not a high, dose of gp120 reversed memory impairment induced by overstimulation of the VIPergic system, a memory-sustaining pathway. Further characterization showed that two strains of gp120 (SF and MN) were equally effective at improving memory and that, unlike other actions of gp120, glycation was not required. We conclude that (1) the predominant cognitive-impairing component of HIV-1 is its viral coat glycoproteins, (2) gp120 impairs memory by overstimulating pathways that normally sustain memory, (3) the cognitive effect of gp120 is mediated by its protein core, and (4) gp120 likely impairs memory by affecting the cholinergic/VIPergic system.

Peripheral nerve exposure to HIV viral envelope protein gp120 induces neuropathic pain and spinal gliosis

Painful sensory neuropathy is a common and debilitating consequence of human immunodeficiency virus (HIV). The underlying causes of neuropathic pain are most likely not due to direct infection of the nervous system by active virus. The goal of this study was to determine whether epineural exposure to the HIV-1 envelope protein gp120 could lead to chronic painful peripheral neuropathy. Two doses of gp120 or BSA control were transiently delivered epineurally via oxidized cellulose wrapped around the rat sciatic nerve. Animals were assessed for neuropathic pain behaviors at several intervals from 1–30 days following nerve surgery. Allodynia and hyperalgesia were observed within 1–3 days following gp120 and sustained throughout the testing period. The gp120-exposed sciatic nerve exhibited early but transient pathology, notably axonal swelling and increased tumor necrosis factor alpha (TNF-α) within the nerve trunk. In contrast, intense astrocytic and microglial activation was observed in the spinal cord, and this gliosis persisted for at least 30 days following epineural gp120, in parallel with neuropathic pain behaviors. These findings demonstrate that limited peripheral nerve exposure to HIV protein can induce persistent painful sensory neuropathy that may be sustained and magnified by long-term spinal neuropathology.