HIV‐1 gp120 upregulates matrix metalloproteinases and their inhibitors in a rat model of HIV encephalopathy

Abstract

Matrix metalloproteinases (MMPs) are implicated in diverse processes, such as neuroinflammation, leakiness of the blood-brain barrier (BBB) and direct cellular damage in neurodegenerative and other CNS diseases. Tissue destruction by MMPs is regulated by their endogenous tissue inhibitors (TIMPs). TIMPs prevent excessive MMP-related degradation of extracellular matrix components. In a rat model of human immunodeficiency virus (HIV)-related encephalopathy, we described MMP-2 and MMP-9 upregulation by HIV-1 envelope gp120, probably via gp120-induced reactive oxygen species. Antioxidant gene delivery blunted gp120-induced MMP production. We also studied the effect of gp120 on TIMP-1 and TIMP-2 production. TIMP-1 and TIMP-2 levels increased 6 h after gp120 injection into rat caudate-putamen (CP). TIMP-1 and TIMP-2 colocalized mainly with neurons (92 and 95%, respectively). By 24 h, expression of these protease inhibitors diverged, as TIMP-1 levels remained high but TIMP-2 subsided. Gene delivery of the antioxidant enzymes Cu/Zn superoxide dismutase or glutathione peroxidase into the CP before injecting gp120 there reduced levels of gp120-induced TIMP-1 and TIMP-2, recapitulating the effect of antioxidant enzymes on gp120-induced MMP-2 and MMP-9. A significant correlation was observed between MMP/TIMP upregulation and BBB leakiness. Thus, HIV-1 gp120 upregulated TIMP-1 and TIMP-2 in the CP. Prior antioxidant enzyme treatment mitigated production of these TIMPs, probably by reducing MMP expression.