Neural progenitor cells (NPC) are present throughout life and replenish neurons and glia (astrocytes and oligodendrocytes) through neurogenesis, a process that requires proper migration, proliferation and differentiation of NPC. Neurogenesis appears to be dysfunctional in neurodegenerative disorders including HIV-1 associated dementia (HAD), Alzheimer's and Parkinson's diseases, where dead or injured neurons are not replaced. HAD is a neurodegenerative disorder where HIV-1-infected and activated brain mononuclear phagocytes (MP; perivascular macrophages and microglia) mediate inflammatory conditions that alter brain homeostasis. We recently demonstrated that HIV-1-infected and activated macrophages inhibit neurogenesis but enhance gliogenesis. We propose this gliogenesis is mediated through brain inflammation attributable to the dysregulation of stromal cell-derived factor 1 (SDF-1). SDF-1 is an endogenous ligand for the chemokine receptor, CXCR4, which is highly expressed on human NPC and mediates NPC migration. Improper SDF-1 and CXCR4 function can affect neural repair by impairing NPC migration. SDF-1 is released in response to glial activation, mediated by inflammatory cytokines from HIV-1-infected and activated MP such as Interleukin one beta (IL-12). SDF-1 is elevated in the cerebrospinal fluid of HAD patients. Activated matrix metalloproteinase-2 (MMP-2) is produced by HIV-1 infected and activated MP and cleaves SDF-1 resulting in a neurotoxic fragment. This proposal will examine the role of HIV-1-infected and activated macrophage in brain inflammation and their effects on neurogenesis. We hypothesize HIV-1-infected and immune- activated MP inhibit neuronal differentiation and promote gliogenesis. Specifically, we propose this shift in neurogenesis is dependent upon SDF-1 produced by activated astrocytes. This gliogenesis may be a consequence of modification/degradation of SDF-1 by factors released from HIV-1-infected MP leading to impairment of normal SDF-1/CXCR4 mediated NPC migration, survival, proliferation and differentiation, generating an environment detrimental to CNS repair. Using our human NPC culture system in a severe combined immune deficient (SCID) HIV-1 encephalitis (HIVE) mouse model, this project will mimic HIV-1-infection and immune-activation of brain MP and investigate the effect of CNS inflammation on neurogenesis. Elucidating the mechanisms of SDF-1/CXCR4 influence on neurogenesis may identify new therapeutic strategies for treating HAD and other neurodegenerative disorders.

Public Health Relevance

Globally, about 40 million people are infected with HIV. 10-20% of these individuals will eventually develop HIV-associated dementia (HAD). This work will elucidate mechanisms through which neurogenesis is affected by HAD, which could identify new therapeutic strategies for treating HAD and other neurodegenerative disorders. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS061642-01A1
Application #
7557981
Study Section
NeuroAIDS and other End-Organ Diseases Study Section (NAED)
Program Officer
Wong, May
Project Start
2008-07-01
Project End
2013-02-28
Budget Start
2008-07-01
Budget End
2009-02-28
Support Year
1
Fiscal Year
2008
Total Cost
$367,500
Indirect Cost
Name
University of Nebraska Medical Center
Department
Pharmacology
Type
Schools of Medicine
DUNS #
168559177
City
Omaha
State
NE
Country
United States
Zip Code
68198
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