Mitochondrial DNA depletion in HIV-infected patients with chronic hepatitis C and effect of pegylated interferon plus ribavirin therapy

BACKGROUND: The metabolic stress derived from high levels of virus replication in both HIV and hepatitis C virus (HCV) infections results in mitochondrial DNA depletion, which seems to be enhanced in co-infected patients. The use of nucleoside analogues to treat HIV infection may further increase mtDNA depletion by inhibiting gamma DNA polymerase. Information on the impact of therapy with pegylated interferon (pegIFN) plus ribavirin on mtDNA is scarce and conflicting results have been reported. PATIENTS AND METHODS: Fifty-nine HCV/HIV-co-infected patients (43 on and 16 off antiretroviral therapy) who initiated treatment with pegIFN plus ribavirin were retrospectively analysed. The amount of mtDNA in peripheral blood mononuclear cells (PBMC) was measured at baseline and at the end of HCV therapy. RESULTS: Mean baseline serum HCV-RNA was 5.8 log IU/ml and 56% of patients were infected by HCV genotype 1. An inverse correlation between serum HCV-RNA levels and PBMC mtDNA content was recognized at baseline (r = -0.370; P = 0.006). HCV-RNA suppression at the end of HCV therapy was associated with a significant increase in mtDNA, particularly in patients with baseline HCV-RNA levels greater than 6 log IU/ml (+61 mtDNA copies/cell) and in subjects not taking antiretroviral therapy (+133 mtDNA copies/cell). CONCLUSION: HCV replication correlates with the extent of mtDNA depletion in PBMC, and treatment of chronic hepatitis C is associated with a significant improvement in mtDNA content. This benefit, however, is not recognized when HCV medications are used along with antiretroviral therapy, probably because of a deleterious interaction of these drugs on mitochondria.     

In Utero Exposure of Female CD-1 Mice to AZT and/or 3TC: II. Persistence of Functional Alterations in Cardiac Tissue

To delineate temporal changes in the integrity and function of mitochondria/cardiomyocytes in hearts from mice exposed in utero to commonly used nucleoside analogs (NRTIs), CD-1 mice were exposed in utero to 80 mg AZT/kg, 40 mg 3TC/kg, 80 mg AZT/kg plus 40 mg 3TC/kg, or vehicle alone during days 12–18 of gestation and hearts from female mouse offspring were examined at 13 and 26 weeks postpartum. Alterations in cardiac mitochondrial DNA (mtDNA) content, oxidative phosphorylation (OXPHOS) enzyme activities, mtDNA mutations, and echocardiography of NRTI-exposed mice were assessed and compared with findings in vehicle-exposed control mice. A hybrid capture-chemiluminescence assay showed significant twofold increases in mtDNA levels in hearts from AZT- and AZT/3TC-exposed mice at 13 and 26 weeks postpartum, consistent with near doubling in mitochondrial numbers over time compared with vehicle-exposed mice. Echocardiographic measurements at 13 and 26 weeks postpartum indicated progressive thinning of the left ventricular posterior wall in NRTI-exposed mice, relative to controls, with differences becoming statistically significant by 26 weeks. Overall, progressive functional changes occurred in mouse mitochondria and cardiac tissue several months after in utero NRTI exposures; AZT and 3TC acted in concert to cause additive cardiotoxic effects of AZT/3TC compared with either drug alone.     

Effects of in utero antiretroviral exposure on mitochondrial DNA levels, mitochondrial function and oxidative stress

Objectives

HIV and antiretroviral (ART) exposure in utero may have deleterious effects on the infant, but uncertainty still exists. The objective of this study was to evaluate aspects of mitochondrial DNA (mtDNA) content, mitochondrial function and oxidative stress simultaneously in placenta, umbilical cord blood and infant blood in HIV/ART‐exposed infants compared with uninfected controls.

Methods

HIV‐1‐infected pregnant women and HIV‐1‐uninfected healthy pregnant controls were enrolled in the study prospectively. Placenta and umbilical cord blood were obtained at delivery and infant blood was obtained within 48 h of delivery. mtDNA content was determined for each specimen. Nuclear [subunit IV of cytochrome c‐oxidase (COX IV)]‐ and mitochondrial (COX II)‐encoded polypeptides of the oxidative phosphorylation enzyme cytochrome c‐oxidase were quantified in cord and infant blood. Placental mitochondria malondialdehyde (MDA) concentrations were measured as a marker of oxidative stress.

Results

Twenty HIV‐positive/HIV‐exposed and 26 control mother–infant pairs were enrolled in the study. All HIV‐infected women and their infants received ART. Placental MDA concentration and mtDNA content in placenta and cord blood were similar between groups. The cord blood COX II:IV ratio was lower in the HIV‐positive group than in the controls, whereas the infant peripheral blood mtDNA content was higher in the HIV‐exposed infants, but the infant peripheral blood COX II:IV ratio was similar. No infant had clinical evidence of mitochondrial disease or acquired HIV infection. In multivariable regression analyses, the significant findings in cord and infant blood were both most associated with HIV/ART exposure.

Conclusions

HIV‐exposed infants showed reduced umbilical cord blood mitochondrial enzyme expression with increased infant peripheral blood mitochondrial DNA levels, the latter possibly reflecting a compensatory mechanism to overcome HIV/ART‐associated mitochondrial toxicity.