Fig. (2).

Roles of cathepsin/cystatin system in the neuropathogenesis induced by HIV-infected macrophages. (1) After HIV infection, ROS and cathepsin B are induced and macrophages undergo oxidative stress triggered by viral proteins. (2) Increased oxidative stress can also induce lysosome disruption and release of cathepsin B from lysosomes (3) with reduced cystatin/cathepsin interactions (4) leading to increased cathepsin B secretion and (5) activity that induce neuronal apoptosis.