An abundance of data suggests that products of activated monocyte-derived cells may contribute to the development of HIV dementia. Prominent monocytic infiltration of the central nervous system (CNS) is observed in association with this condition. Moreover, the degree of macrophage activation and the CNS levels of macrophage derived products, including TNF-alpha and prostaglandin E2, correlate with dementia severity. One mechanism by which the products of activated monocytes may contribute to disease is through direct effects, including TNF-alpha and/or eicosanoid mediate neurotoxicity. Another mechanism by which these products may contribute to disease, however, is through their ability to stimulate the production of matrix metalloproteinases (MMPs) from CNS- resident cells. MMPs can affect the ability of inflammatory cells to cross the blood brain barrier (BBB) and to migrate within the CNS parenchyma itself. In addition, through their effects on BBB permeability, MMPs may allow systemic cytokines and other toxins to more easily enter the CNS. It is also possible, however, that through their effects on neuronal lands and receptors, MMPs could more directly affect neuronal function. Therefore, in order to improve our understanding of those mechanisms that might contribute to the development of HIV dementia, and to potentially gain information with respect to specific therapeutics, the applicants aim to test the following hypotheses: 1) that specific cytokines, which are elevated in association with HIV dementia, increase the production of select MMPs from CNS derived cells, 2) that these MMPs may be neurotoxic, and 3) that the production, release and/or activity of these MMPs can be reduced by specific antagonists. Experiments will include analysis of supernatants from cytokine stimulated cells by ELISA and Western blot, as well as by collagen, laminin an gelatin substrate zymography. In addition, cultured neurons will be stimulated with select MMPs, as well as with supernatants from cytokine stimulated CNS derived cells, both in the presence and in the absence of specific antibodies/antagonists. Also, compounds including the hydroxamic acid maramastat as well as select anti- oxidants and anti-inflammatory drugs, will be tested for their ability to inhibit the production, release and/or activity of specific MMPs.
