Objective: Investigate the metabolic and mitochondrial effects of switching a highly active antiretroviral therapy (HAART) regimen with a high mitochondrial toxicity profile to a HAART with a theoretically low mitochondrial toxicity.
Patients and methods: Six consecutive HAART-experienced patients receiving at least one dideoxy-nucleoside reverse transcriptase inhibitor (NRTI) switched to enfuvirtide plus tenofovir plus saquinavir/ritonavir (T20+TDF+SQV/r). Blood samples were collected at baseline, 12 and 24 weeks after the switch, and viral load (VL) and lymphocyte CD4+ T-cell count were determined. Metabolic parameters consisted of fasting serum triglycerides, cholesterol (total and fractions), glucose, insulin, C-peptide and lactate. Mitochondrial assessment consisted on mitochondrial DNA (mtDNA) quantification, COX-II mitochondrial protein expression rate, mitochondrial respiratory chain complex III and IV activities, and oxygen consumption in peripheral blood mononuclear cells. For baseline mitochondrial comparisons, we included six HIV-infected patients naive for ART.
Results: Switched patients exhibited a mean increase of 26 CD4+ T-cells/mm3 and a mean decrease of 1.1 log in VL (P = NS for both). Lactate, lipids and glycaemia remained stable during the study; only insulin levels increased significantly (P < 0.05). Switched patients exhibited, at baseline, low mitochondrial measurements, being significant only for complex III and IV activities with respect to naive patients (P < 0.05 for both). MtDNA content did not rise significantly during the study. However, we observed increases in COX-II mitochondrial protein synthesis (124%, P < 0.05), complex III activity (127%, P < 0.05), complex IV activity (86%, P = 0.37) and oxygen consumption (194%, P < 0.05).
Conclusion: Switching a HAART-containing dideoxy-NRTI to T20+TDF+SQV/r minimally alters metabolic parameters and exerts beneficial effects on mitochondrial function at 24 weeks. Mitochondrial improvement should be considered as an additional advantage of this rescue therapy.