The long-term goals are to understand the neuropathogenesis of HIV-associated dementia (HAD), a syndrome in which patients show motor, cognitive, and behavioral impairments. While neuronal loss is a characteristic feature of HAD, the HIV virus does not infect neurons themselves. Rather, oxidative stress has a substantial role in the pathologic progression of HAD. NF-E2 related factor 2 (Nrf2) is the primary transcription factor responsible for regulating the induction of endogenous cellular antioxidant mechanisms, through its interaction with the antioxidant-response element (ARE) found in the promoter region of genes encoding phase II detoxification enzymes and antioxidant proteins. In non-neural cells, studies have identified numerous points of Nrf2 regulation, however, both the precise function and the regulation of Nrf2 in the CNS remain under explored. We have found increased Nrf2 protein levels both in astrocytes in an in vitro model of neuronal damage in HAD and overall in prefrontal cortical autopsy tissue from HAD patients. Based on these findings, we hypothesize that CNS cells may be attempting to mount a neuroprotective antioxidant response to oxidative stress in HAD, but that the endogenous protection usually provided by Nrf2 is unable to prevent neuronal death in individuals with this disease. In this proposal we will examine Nrf2 function and regulation in neuroglial cells with the aim of understanding how this normally protective response fails to ensure neuronal survival in HAD.
Specific aim 1 will examine the Nrf2 response in neuroglial cells in an in vitro model of neuronal death in HAD and in HAD autopsy brain tissue using immunofluorescence and Western blotting.
Specific aim 2 will use viral vector-mediated overexpression of Nrf2 and siRNA-mediated knockdown of Nrf2 to examine the neuroprotective capabilities of Nrf2 in primary neuroglial cultures responding to supernatants from HJV-infected macrophages.
Specific aim 3 will utilize co- immunoprecipitation and chromatin immunoprecipitation to investigate Nrf2 regulatory binding partners in neuroglial cells in primary cultures and in autopsied HAD brain tissue. Understanding the processes controlling Nrf2 activity and the points at which they fail in HAD, will offer potential novel molecular targets in the treatment of this disease.
TO PUBLIC HEALTH: Oxidative stress has a substantial role in the pathological expression of HAD, and in that of other neurodegenerative diseases. Understanding the capability of neuroglial cells to mount an antioxidant response and the mechanism by which they do so will potentially provide numerous points for therapeutic intervention in HAD that may be applicable to multiple neurodegenerative disorders. ? ? ?
| Lindl, Kathryn A; Marks, David R; Kolson, Dennis L et al. (2010) HIV-associated neurocognitive disorder: pathogenesis and therapeutic opportunities. J Neuroimmune Pharmacol 5:294-309 |
