Neuroprotective and antiretroviral effects of the immunophilin ligand GPI 1046

HIV infection results in a neurodegenerative disorder for which currently there is no effective therapy available. Currently, available antiretroviral therapy has no impact on the production of early regulatory HIV proteins once the virus is integrated. Of these proteins, Tat was shown to be toxic to neurons. We, thus, used an in vitro neuronal culture system to determine if immunophilin ligands could protect against Tat-induced neurotoxicity. We found that GPI 1046 had potent neuroprotective effects in this model. The compound was able to protect the neurons even though it only partially obliterated Tat-induced oxidative stress in neurons, suggesting that other mechanisms may be important in mediating its neuroprotective effect. Furthermore, GPI 1046 showed inhibition of HIV replication and Tat-mediated long terminal repeat (LTR) activation suggesting that this class of compounds may be worthy of further exploration as a potential treatment for HIV dementia.