Role of Macrophage Activation in the Pathogenesis of Alzheimer's Disease and Human Immunodeficiency Virus Type 1-associated Dementia

The structure and function of neurons are changed not only during development of the central nervous system but also in certain neurological disorders, such as Alzheimer's disease and human immunodeficiency virus type 1 (HIV-1) -associated dementia. Immunological activation and altered production of neurotoxins and neurotrophins by brain macrophages are thought to play an important role in neuronal structure and function. This review describes the clinical and pathological features of both Alzheimer's disease and HIV-1-associated dementia and tries to interpret the role of the macrophage and astrocytes therein. The consequences of activation of macrophages by amyloid-beta in Alzheimer's disease and HIV infection of macrophages in HIV-1-associated dementia and the similarities between these diseases will be discussed. Although the neuropathology of Alzheimer's disease and HIV-1-associated dementia differs, Alzheimer's disease is a cortical dementia and HIV-1-associated dementia is a subcortical dementia, the process of macrophage activation and the resulting pathways leading to neurotoxicity seem very similar. In both Alzheimer's disease and HIV-1-associated dementia, interaction of macrophages and astrocytes appear to play an important role.