Erythrocebus patas monkey offspring exposed perinatally to NRTIs sustain skeletal muscle mitochondrial compromise at birth and at 1 year of age

Antiretroviral nucleoside reverse transcriptase inhibitors (NRTIs), given to human immunodeficiency virus-1-infected pregnant women to prevent vertical viral transmission, have caused mitochondrial dysfunction in some human infants. Here, we examined mitochondrial integrity in skeletal muscle from offspring of pregnant retroviral-free Erythrocebus patas dams administered human-equivalent NRTI doses for the last 10 weeks of gestation or for 10 weeks of gestation and 6 weeks after birth. Exposures included no drug, Zidovudine (AZT), Lamivudine (3TC), AZT/3TC, AZT/ Didanosine (ddI), and Stavudine (d4T)/3TC. Offspring were examined at birth (n = 3 per group) and 1 year (n = 4 per group, not including 3TC alone). Circulating levels of creatine kinase were elevated at I year in the d4T/3TC-exposed group. Measurement of oxidative phosphorylation enzyme activities (complexes 1, 11, and IV) revealed minimal NRTI-induced changes at birth and at I year. Histochemistry for complex IV activity showed abnormal staining with activity depletion at birth and I year in groups exposed to AZT alone and to the 2-NRTI combinations. Electron microscopy of skeletal muscle at birth and 1 year of age showed mild to severe mitochondrial damage in all the NRTI-exposed groups, with 3TC inducing mild damage and the 2-NRTI combinations inducing extensive damage. At birth, mitochondrial DNA (mtDNA) was depleted by similar to 50% in groups exposed to AZT alone and the 2-NRTI combinations. At I year, the mtDNA levels had increased but remained significantly below normal. Therefore, skeletal muscle mitochondrial compromise occurs at birth and persists at I year of age (46 weeks after the last NRTI exposure) in perinatally exposed young monkeys, suggesting that similar events may occur in NRTI-exposed human infants.

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