3rd Conf Retro and Opportun Infect. 1996 Jan 28-Feb 1;:172. Unique
HIV-1 neuropathogenesis can be divided into three important
components:1) virus entry/virus localization in the nervous system, 2)
the role of viral proteins and/or cellular products in neural tissue
damage, and 3)the mechanism(s) of neuronal dysfunction/damage/death. The
major cell type harboring productive HIV-1 infection in the nervous
system is the perivascular macrophage. It is not known if these are
blood derived macrophages or resident brain microglia secondarily
infected by trafficking of HIV infected T-lymphocytes. HIV-1 infection
of brain astrocytes restricted to the expression of regulatory gene
products has been described that may cause astrocyte dysfunction and
contribute to neuronal injury or to disruption of the blood-brain
barrier (BBB). Studies of the CSF and of postmortem tissues reveal a
state of chronic inflammation/immune activation in the nervous system
during the later stages of HIV-1 infection associated with disruption of
BBB integrity. BBB damage may underlie the white matter pallor described
in HIV-1 infection and could result in further entry into the nervous
system of toxic viral or cellular products, or additional HIV-1 infected
cells. HIV infected macrophages produce excessive amounts of
pro-inflammatory cytokines, including tumor necrosis factor alpha, and
platelet activating factor. These products are directly toxic to human
neurons in vitro. The HIV-1 envelope glycoprotein, gp 120 may stimulate
the release of toxic factors from brain macrophages. These candidate
toxins of both viral and cellular origin can be antagonize by blocking
NMDA (or AMPA) glutamate receptors. It has been postulated that (weak)
excitotoxicity leads to oxidative stress in nerons and ultimately to
apoptosis. Neuronal apoptosis has recently been described in the brains
of both children and adults with HIV-1 infection.
Astrocytes/VIROLOGY Brain Diseases/*COMPLICATIONS HIV
Infections/*COMPLICATIONS HIV-1/ISOLATION & PURIF Human
Macrophages/VIROLOGY Microglia/VIROLOGY ABSTRACT