33 million individuals worldwide are infected with HIV. Acquired immunodeficiency syndrome is now staved off by antiretroviral (ARV) drugs which suppress viral replication and restore immune system function. However, 50% of individuals suffer from some form of neurological impairment, termed HIV-Associated Neurocognitive Disorder (HAND). Oxidative stress has been clearly demonstrated in the brain and cerebral spinal fluid of individuals suffering from HAND, even with effective ARV therapy. HIV and secreted products from infected macrophages induce oxidative stress. Additionally, antiretroviral compounds, in the absence of viral infection, have been shown to produce ER and oxidative stress, reactive oxygen species (ROS) and neuronal damage. ARV drugs induce ROS in neurons, yet result in neuronal toxicity in cortical neuroglial culture. The first goal of this work is to concretely demonstrate neuronal endogenous antioxidant response (EAR) pathway involvement in response to media from HIV-infected macrophages and ARVs. Nrf2 is the transcription factor responsible for the EAR. Nrf2 localization and effector protein transcription and translation will be determined, as will levels of ROS. White matter pathologies in HAND are more prevalent in the era of effective viral suppression. No studies to date have examined direct effects of ART on cell populations of the oligodendrocyte lineage. While a single study reported decreased in vitro myelination in the presence of viral protein gp120, the effects of HIV-infected macrophages have not been characterized. The second goal of this proposal will address the direct effects of HIV and antiretroviral compounds on mature and developing oligodendrocytes. Cellular morphology, maturation, and viability will be ascertained through immunofluorescent staining, probing for levels of mRNA and protein, and cell death assays. It will be determined if oxidative stress evoked through HIV/ART alters maturation of these cells. Upregulation of the EAR in all cell populations of the brain may be an effective adjunctive to ART regimens. Higher endogenous antioxidant activity would lower cellular ROS induced by the virus and ARVs by promoting defenses against oxidative stress.
The final aim of this proposal will investigate the potential protective effects of elevated Nrf2 activity levels in the context of an oxidant challeng. EAR upregulation will be achieved through administration of the antioxidant monomethyl fumarate in neuroglial and oligodendrocyte culture. Effects of HIV/ART toxicity on these cultures will be compared to those with basal Nrf2 activity levels. Levels of ROS, oxidative damage, and cell death will be assayed. This work will provide an understanding of Nrf2 pathway regulation in well characterized neuroglial and oligodendrocyte culture systems. Once understood, targeted modulation can be utilized to attenuate oxidative damage and cell death. Translation of findings to an in vivo setting will provide a novel endogenous therapeutic avenue to potentially lessen severity or speed of progression of neurodegenerative diseases displaying evidence of oxidative stress.
Of the 33 million individuals worldwide infected with HIV, 50% display motor, cognitive, and behavioral disturbances termed HIV-Associated Neurocognitive Disorder (HAND). Antiretroviral drugs restore immune system function and suppress viral replication, yet viral pockets persist in the central nervous system necessitating permanent adherence to drug regimens;both virus and antiretrovirals by themselves produce oxidative stress and cellular death and may contribute to neuronal and oligodendrocyte damage in HAND. This study will address whether the antioxidant response, which combats oxidative stress, is activated by HIV and antiretroviral agents in neurons and supportive brain cells, and if upregulation of endogenous protection attenuates the induced oxidative stress and cellular toxicities from these treatments.
|Jensen, Brigid K; Monnerie, Hubert; Mannell, Maggie V et al. (2015) Altered Oligodendrocyte Maturation and Myelin Maintenance: The Role of Antiretrovirals in HIV-Associated Neurocognitive Disorders. J Neuropathol Exp Neurol 74:1093-118|