Detection of HIV‐1 DNA in Microglia/ Macrophages, Astrocytes and Neurons Isolated from Brain Tissue with HIV‐1 Encephalitis by Laser Capture Microdissection

Abstract

In HIV‐1 encephalitis, HIV‐1 replicates predominantly in macrophages and microglia. Astrocytes also carry HIV‐1, but the infection of oligodendrocytes and neurons is debated. In this study we examined the presence of HIV‐1 DNA in different brain cell types in 6 paraffin embedded, archival post‐mortem pediatric and adult brain tissues with HIV‐1 encephalitis by Laser Capture Microdissection (LCM). Sections from frontal cortex and basal ganglia were stained by immunohistochemistry for CD68 (microglia), GFAP (astrocytes), MAP2 (neurons), and p24 (HIV‐1 positive cells) and different cell types were microdissected by LCM. Individual cells or pools of same type of cells were lysed, the cell lysates were subjected to PCR using HIV‐1 gag SK38/SK39 primers, and presence of HIV‐1 DNAwas confirmed by Southern blotting. HIV‐1 gag DNAwas consistently detected by this procedure in the frontal cortex and basal ganglia in 1 to 20 p24 HIV‐1 capsid positive cells, and in pools of 50 to 100 microglia/macrophage cells, 100 to 200 astrocytes, and 100 to 200 neurons in HIV‐1 positive cases but not in HIV‐1 negative controls. These findings suggest that in addition to microglia, the infection of astro‐cytes and neurons by HIV‐1 may contribute to the development of HIV‐1 disease in the brain.

Roles of MCP-1 in development of HIV-dementia

“…HIV encephalitis (HIVE), the pathologic correlate of HAD is characterized by the presence of unusually large numbers of HIV-infected macrophages in the brain, formation of multinucleated giant cells, activation of astrocytes and microglia, all accompanied by cytokine/ chemokine dysregulation, and neuronal degeneration (7,(11)(12)(13)(14). The highly productive infection in macrophages in the brain is also accompanied by an abortive infection in astrocytes [15][16][17][18]. Although the primary cell types infected by HIV-1 in the brain are macrophages/ microglia, and to a lesser extent, astrocytes but not neurons, the low numbers of infected cells in the brain do not correlate with the severity of encephalopathy.…”

Differential long‐term neurotoxicity of HIV‐1 proteins in the rat hippocampal formation: A design‐based stereological study

“…Whether clinical and pathological substrates of HIV-1 infection can be attributed to the direct action of the virus on neurons itself is currently debated (Bagasra et al, 1996;TorresMunoz et al, 2001;Trillo-Pazos et al, 2003). A study assessing the hippocampus in brains from six adult and two pediatric AIDS patients demonstrated the latent infection of neurons by the virus in vivo (Torres-Munoz et al, 2001).…”

Past Stimulant Abuse is Associated with Reduced Basal Ganglia and Hippocampal Integrity in Older HIV+ Adults: A Diffusion Tensor Imaging Study

“…Histopathological investigations of postmortem brain tissue have demonstrated the highest levels of HIV in the basal ganglia [40,41]. Examinations of biochemical metabolites have observed lower levels of N-acetylaspartate (a marker of neuronal integrity) and higher levels of choline and myoinsonital (markers of inflammation and cell turn over) in the basal ganglia of HIV infected patients.…”