Human immunodeficiency virus (HIV)-1 infection of the central nervous system occurs in the vast majority of HIV infected patients. HIV-associated dementia (HAD) represents the most severe form of HIV-related neuropsychiatric impairment and is associated with neuropathology involving HIV proteins and activation of proinflammatory cytokine circuits. Interferon-γ (IFN-γ) activates the JAK/STAT1 pathway, a key regulator of inflammatory and apoptotic signaling, and is elevated in brains of HIV-1 infected brains progressing to HAD. Recent reports suggest that green tea derived (-)-epigallocatechin-3-gallate (EGCG) can attenuate neuronal damage mediated by this pathway in conditions such as brain ischemia. In order to investigate the therapeutic potential of EGCG to mitigate the neuronal damage characteristic of HAD, IFN-γ was evaluated for its ability to enhance well-known neurotoxic properties of HIV-1 proteins gp120 and Tat in primary neurons and mice. Indeed, IFN-γ enhanced the neurotoxicity of gp120 and Tat via increased JAK/STAT signaling. Additionally, primary neurons pretreated with a JAK1 inhibitor or those derived from STAT1-deficient mice were largely resistant to the IFN-γ enhanced neurotoxicity of gp120 and Tat. Moreover, EGCG treatment of primary neurons from normal mice reduced IFN-γ enhanced neurotoxicity of gp120 and Tat, while attenuating JAK/STAT1 pathway activation. EGCG was also found to attenuate the neurotoxic properties of HIV-1 proteins in the presence of IFN-γ in vivo. Taken together, these data suggest that EGCG attenuates the neurotoxicity of IFN-γ augmented neuronal damage from HIV-1 gp120 and Tat both in vitro and in vivo. Thus EGCG ‡

Rapamycin is a well known immunosuppressant drug for rejection prevention in organ transplantation. Numerous clinical trials using rapamycin analogs, involving both children and adults with various disorders are currently ongoing worldwide. Most recently, rapamycin gained much attention for what appears to be life-span extending properties when administered to mice. The risk for Alzheimer disease (AD) is strongly and positively correlated with advancing age and is characterized by deposition of β-amyloid peptides (Aβ) as senile plaques in the brain. We report that rapamycin (2.5 μM), significantly increases Aβ generation in murine neuron-like cells (N2a) transfected with the human "Swedish" mutant amyloid precursor protein (APP). In concert with these observations, we found rapamycin significantly decreases the neuroprotective aminoterminal APP (amyloid precursor protein) cleavage product, soluble APP-α (sAPP-α) while increasing production of the β-carboxyl-terminal fragment of APP (β-CTF). These cleavage events are associated with decreased activation of a disintegrin and metallopeptidase domain-10 (ADAM-10), an important candidate α-secretase which opposes Aβ generation. To validate these findings in vivo, we intraperitoneal (i.p.) injected Tg2576 Aβ-overproducing transgenic mice with rapamycin (3 mg/kg/day) for 2 weeks. We found increased Aβ levels associated with decreased sAPP-α at an average rapamycin plasma concentration of 169.7 ± 23.5 ng/mL by high performance liquid chromatography (HPLC). These data suggest that although rapamycin may increase the lifespan in some mouse models, it may not decrease the risk for age-associated neurodegenerative disorders such as AD.