Studies show that 60% of HIV-1 carriers have some form of neuropsychiatric impairment. HIV associated dementia (HAD), the most severe form of HIV-1 induced CNS impairment, is the main cause of dementia in people 60 or younger. HIV-Encephalitis (HIVE), the pathologic correlate of HAD, is characterized by widespread astrogliosis, cytokine/chemokine dysregulation, oxidative stress, and neuronal degeneration. Astrocytes, the most numerous cell type within the brain, provide an important reservoir for the generation of inflammatory mediators, in response to HIV-1 infiltration into the brain. One of the inflammatory mediators expressed by stimulated astrocytes is CXCL10, a neurotoxin and chemoattractant whose expression can be induced by HIV-1/viral proteins and the cytokines IFN-y and TNF-a. The long term goal of this study is to test the hypothesis that in HAD antioxidant therapy can reduce the neuronal loss by lowering the levels of CXCL10 in the brain. This will be accomplished in three aims: 1) Examine the potential cellular and molecular mechanism(s) by which HIV-1 synergizes with IFN-y &TNF-a to induce the expression of CXCL10 in astrocytes. 2) Study the role of oxidative stress in the synergistic induction of CXCL10 in astrocytes exposed to HIV-1/IFN-v/TNF-a. 3) Examine the efficacy of using the antioxidant, N-acetyl cysteine (MAC), as a therapy for abrogating CXCL10 release from HIV- 1/IFN-y/TNF-a stimulated astrocytes.
Aims 1 &2 will investigate MARK signaling pathways that activate NF-KB mediated transcription of CXCL10 in stimulated astrocytes. Methods: Western blot analysis to confirm the phosphorylation of MARK proteins, CXCL10 ELISA to determine pathways necessary for CXCL10 production, and electrophoretic mobility shift assay (EMSA) to determine NF-KB activity. Rationale: NF-KB, a known transcription factor for CXCL10, is affected by the signaling cascades caused by HIV-1/viral proteins, IFN-y/TNF- a, and oxidative stress.
Aim 3 will utilize immunocytochemistry and lactate dehydrogenase (LDH) assays to determine whether NAC treatment of stimulated astrocytes can reduce CXCL10 mediated neuronal toxicity. Rationale: in HIVE there is increased neuronal death along with increased CXCL10 and oxidative stress. Therefore the CXCL10 released by stimulated astrocytes could play a central role in HAD neuropathogenesis, and antioxidant therapy may be a mechanism for preventing the neuronal loss associated with this disease.
Patients suffering from HAD have increased levels of CXCL10 and oxidative stress. Antioxidant therapy for HAD patients has the potential to reduce oxidative stress and the neurotoxicity caused by CXCI10. If this form of intervention is successful it could be used in conjunction with the currently available antiretroviral drugs, which are often ineffective in the CNS.
| Williams, Rachel; Yao, Honghong; Peng, Fuwang et al. (2010) Cooperative induction of CXCL10 involves NADPH oxidase: Implications for HIV dementia. Glia 58:611-21 |
| Williams, Rachel; Yao, Honghong; Dhillon, Navneet K et al. (2009) HIV-1 Tat co-operates with IFN-gamma and TNF-alpha to increase CXCL10 in human astrocytes. PLoS One 4:e5709 |
| Williams, Rachel; Dhillon, Navneet K; Hegde, Sonia T et al. (2009) Proinflammatory cytokines and HIV-1 synergistically enhance CXCL10 expression in human astrocytes. Glia 57:734-43 |
| Williams, Rachel; Bokhari, Sirosh; Silverstein, Peter et al. (2008) Nonhuman primate models of NeuroAIDS. J Neurovirol 14:292-300 |
