HIV This Week

Hauser KF, El-Hage N, Buch S, Nath A, Tyor WR, Bruce-Keller AJ, Knapp PE. Impact of opiate-HIV-1 interactions on neurotoxic signaling. J Neuroimmune Pharmacol. 2006; 1(1):98-105.

Opiate drug abuse exacerbates the pathogenesis of human immunodeficiency virus-1 (HIV-1) in the central nervous system through direct actions on glia and neurons. Opiate abuse causes widespread disruption of astroglial and microglial function, and significant increases in astroglial-derived proinflammatory cytokines and chemokines, which likely contributes to neuronal dysfunction, death, and HIV encephalitis. Neurons are also directly affected by opiate-HIV-1 interactions. HIV-1 and the viral proteins gp120 and Tat activate multiple caspase-dependent and caspase-independent proapoptotic pathways in neurons involving phosphatidylinositol 3-kinase (PI3 kinase)/Akt, as well as p38, c-Jun N-terminal kinase (JNK) and/or other mitogen-activated protein kinases (MAPKs). Opiates appear to decrease the threshold for HIV-1-mediated neurotoxicity by sending convergent signals that exacerbate proapoptotic events induced by viral and cellular toxic products. The synergistic proinflammatory and neurotoxic effects of opiate drugs on glia and neurons are largely mediated through mu opioid receptors, which are expressed by subpopulations of astroglia, microglia, and neurons. Opiate abuse intrinsically modifies the host response to HIV-1. Identification of how this occurs is providing considerable insight toward understanding the mechanisms underlying HIV-1-associated dementia.

Editors’ note: HIV can cause neurotoxicity leading to symptoms and signs of dementia in some individuals and not others. Substances may exist that can counter this HIV-induced neurotoxicity but opiates are certainly not among them. Opiates appear to confuse neural communications and increase inflammation, undermining natural defences.

Human immunodeficiency virus type 1 (HIV-1) protease plays an essential role in the life cycle of the virus. Consequently, its inhibition can control acquired immunodeficiency syndrome. Any pharmacological treatment targeting the active site of the protease is known to generate escape mutants. On the other hand, if a drug targets a site crucial for the correct folding of the protease, mutations affecting this region would denaturate the protein and thus will not be expressed. Broglia and colleagues review the progress in our understanding of the folding of the protease, which has been instrumental in the design of a (non-conventional) folding inhibitor. The transferability of these results to other proteins testify to the universality of the folding-inhibition scenario for the design of leads of drugs which are unlikely to generate resistance.

Editors’ note: A drug that could incapacitate HIV’s protease by inhibiting it from folding into an action position, without producing an escape mutant, would be an important step forward.