Background: In vitro studies have reported controversial effects of protease inhibitors (PIs) on mitochondrially driven apoptosis. Additionally, since PIs in the clinical setting are almost always given in combination with nucleoside analogues, which may have negative effects on mitochondrial DNA (mtDNA), the impact of PI-containing highly active antiretroviral therapy (HAART) on apoptosis and mtDNA content is unclear.
Patients and methods: A cross-sectional study was performed including 20 HIV-negative (HIV-) patients, 16 HIV-positive, antiretroviral-naive (HIV+) patients and 17 HIV-positive patients receiving the PI nelfinavir (NFV) plus zidovudine and lamivudine (AZT+3TC) or didanosine and stavudine (ddl+d4T)--collectively known as HIV+PI--as first-line antiretroviral treatment for at least 12 months. Peripheral blood mononuclear cells (PBMCs) were isolated. BCL2 expression (anti-apoptotic) and the levels of the cleaved, active form of caspase-9 (pro-apoptotic) were determined by western blot. An index of mitochondrially driven apoptotic activation was estimated calculating the ratio caspase-9:BCL2. Mitochorldrial DNA content was measured by real-time PCR.
Results: BCL2 expression was lower in HIV+ than in HIV-patients (P < 0.01), whereas levels of caspase-9 were higher (P = 0.001). The caspase-9:BCL2 ratio was significantly increased in HIV+ compared with HIV-individuals (P < 0.001). Mitochondrial DNA content was also decreased in HIV+ compared with HIV-patients (P < 0.001). The HIV+PI group exhibited a trend to normalization for BCL2 expression and caspase-9 compared with the HIV+ group, whereas the caspase-9:BCL2 ratio significantly improved (decreased, P < 0.05 compared with HIV+ group). The mtDNA content in the HIV+PI group was similar to that of the HIV+ group, although the results of mtDNA content differed depending on whether NFV was combined with AZT+3TC (preserved) or with ddl+d4T (depleted). Conversely, no differences were found in apoptotic markers between the two subgroups of HIV+PI.
Conclusions: NFV-based PI-containing HAART regimens may exert some beneficial effects counteracting the increased mitochondrially driven apoptosis present in HIV-infected people.