Hepatic mitochondrial oxidative stress, AIDS and alcohol

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DESCRIPTION (provided by applicant): This project elucidates subcellular mechanisms of hepatic mitochondrial damage from the combination of alcohol and nucleoside reverse transcriptase inhibitors (NRTIs) for AIDS. Defective mitochondrial (mt-) DNA replication, oxidative stress (imbalance between free radicals and antioxidant defenses), and hepatic microvesicular steatosis (fatty liver) are features of NRTIs, the alcoholic liver, and HIV infection. The NRTI zidovudine (3'-azido-2',3'-deoxythymidine; AZT) depletes mtDNA, causes microvesicular hepatic steatosis (a potentially lethal liver disease), and oxidative stress. Based on their chemical structure, NRTI triphosphates inhibit DNA pol-gamma (the enzyme that replicates mtDNA) competitively or with mixed kinetics and deplete mtDNA. Hepatic steatosis, mtDNA depletion and mutation and result from alcohol. HIV tat (the transactivator) depletes hepatic mitochondrial glutathione (GSH) and contributes to oxidative stress. Combined effects of alcohol, AIDS and NRTIs are unknown, but potentiation from each is a logical outcome. The working hypothesis states: Hepatic mitochondrial damage from the combination of NRTIs (for AIDS) and alcohol is worse than that from each. Mechanisms include defective mtDNA replication and mutation, energy depletion, and oxidative stress. Transgenic AIDS mice (TGs) are specialized "biological tools". TGs are treated with alcohol and NRTIs in the proposed experiments. Targeted TGs that express HIV tat exclusively in hepatocytes (driven by albumin promoter) pinpoint liver-specific effects. TGs that ubiquitously express HIV tat (driven by B-actin promoter) identify systemic effects. TGs that express NL4-3Agaglpol ubiquitously are models of systemic HIV. Alcohol is administered by paired feeding. NRTI treatments resemble clinically useful ones. Biochemical, pathological and pharmacological studies address the following Specific Aims: 1) to define hepatic mitochondrial biogenesis, function, and oxidative stress from NRTIs and alcohol. Decreased mtDNA, mtRNA, mitochondrial proteins, and GSH/GSSG, increased 8-OHdG, and aconitase inactivation are expected; 2) to define hepatic steatosis morphometrically (light and transmission electron microscopy) in NRTI therapy with alcohol. Quantitative differences in hepatocyte damage (eg., altered mitochondrial structure) are observed. Combined effects are worse than those found with each individual condition; and 3) to reduce mitochondrial damage from AIDS NRTIs and alcohol using antioxidants or S-adenosylmethionine. Biochemical, molecular and pathological changes (above) are ameliorated. This serves as a "proof of principle".