Genetic and Metabolic Control of the Mitochondrial Transmembrane Potential and Reactive Oxygen Intermediate Production in HIV Disease

Abstract

Redox mechanims play important roles in replication of human immunodeficiency virus type 1 (HIV-1) and cellular susceptibility to apoptosis signals. Viral replication and accelerated turnover of CD4⁺ T cells occur throughout a prolonged asymptomatic phase in patients infected by HIV-1. Disease development is associated with steady loss of CD4⁺ T cells by apoptosis, increased rate of opportunistic infections and lymphoproliferative diseases, disruption of energy metabolism, and generalized wasting. Such pathological states are preceded by: (i) depletion of intracellular antioxidants, glutathione(GSH) and thioredoxin (TRX), (ii) increased reactive oxygen species (ROS) production, and (iii) changes in mitochondrial transmembrane potential (ΔΨ_m). Disruption of ΔΨ_m appears to be the point of no return in the effector phase of apoptosis. Viral proteins Tat, Nef, Vpr, protease, and gp120, have been implicated in initiation and/or intensification of oxidative stress and disruption of ΔΨ_m. Redox-sensitive transcription factors, NF-κB, AP-1, and p53, support expression of viral genes and proinflammatory lymphokines. ROS regulate apoptosis signaling through Fas, tumor necrosis factor (TNF), and related cell death receptors, as well as the T-cell receptor. Oxidative stress in HIV-infected donors is accompanied by increased glucose utilization both on the cellular and organismal levels. Generation of GSH and TRX from their corresponding oxidized forms is dependent on NADPH provided through the pentose phosphate pathway of glucose metabolism. This article seeks to delineate the genetic and metabolic bases of HIV-induced oxidative stress. Such understanding should lead to development of effective antioxidant therapies in HIV disease.