Background:  Mitochondrial DNA (mtDNA) content of peripheral blood mononuclear cells (PBMC) has been suggested as a potential marker of mitochondrial toxicity associated with antiretroviral therapy, whereas mitochondrial RNA (mtRNA) has not been studied. Compared to HIV-1 negative controls, reduced mtDNA content of PBMC has been reported in untreated HIV-1 infected individuals. We performed a longitudinal assessment of mtDNA and mtRNA content in prospectively collected, cryopreserved PBMCs of subjects in the European Asian South American Indinavir, Efavirenz, Ritonavir (EASIER) study. This study randomly compared IDV 800/RTV 100 mg twice daily + EFV 600 mg once daily + d4T in PI-, d4T-, and NNRTI-naïve patients with ≥100 CD4 cells/mm³ and HIV-RNA ≥1000 copies/mL.

Methods:  Sequential PBMC samples obtained at weeks 0, 12, 24, 36, and 48 were available for 78 patients (from a total of 96) enrolled in the trial, 73 of whom were ART-naïve. Of the 78 patients, 38 were in the d4T-sparing and 40 in the d4T-containing arm. MtDNA and mtRNA content were determined by means of Retina Mitox. Adverse events, classified as either clinical or ≥ ACTG grade 3 laboratory or both and which could potentially be attributed to mitochondrial toxicity, were retrospectively extracted from the trial database.

Results:  No statistically significant difference in the course of mtDNA and mtRNA levels was found between both treatment arms. When arms were combined, both median mtDNA and mtRNA showed a statistically significant increase over 48 weeks from 206 to 278 copies/cell (p <0.0001) and 154 to 288 copies/cell (p = 0.02), respectively. Analysis of patients with either clinical (n = 15) or both clinical and laboratory (n = 21) adverse events versus those without, did not yield a statistically significant difference in the course of mtDNA (p = 0.23 and p = 0.84) and mtRNA (p = 0.30 and p = 0.66), respectively.

Conclusions:  The observed increase in mtDNA during the first year of treatment, may represent a restorative trend resulting from initial suppression of HIV-1, independent of the treatments used in this trial. The results of the adverse events analysis from this trial question the utility of mtDNA and mtRNA quantification in PBMC as a readily obtainable marker for potential mitochondrial-related adverse events. Studies of adverse events associated with specific organ systems may possibly reveal a correlation between such events and changes in mtDNA and/or mtRNA content in relevant tissues.

Keywords: mitochondrial toxicity; antiretroviral combination therapy; mtDNA content