HIV-associated cardiomyopathy (HIVCM) is of clinical concern in developing countries because of a high HIV-1 prevalence, especially subtype C, and limited access to highly active antiretroviral therapy (HAART). For these reasons, we investigated the direct and indirect effects of HIV-1 subtype C infection of cultured human cardiomyocytes and the mechanisms leading to cardiomyocytes damage; as well as a way to mitigate the damage. We evaluated a novel approach to mitigate HIVCM using a previously reported gp120 binding and HIV-1 neutralizing aptamer called UCLA1. We established a cell-based model of HIVCM by infecting human cardiomyocytes with cell-free HIV-1 or co-culturing human cardiomyocytes with HIV-infected monocyte derived macrophages (MDM). We discovered that HIV-1 subtype C unproductively (i.e. its life cycle is arrested after reverse transcription) infects cardiomyocytes. Furthermore, we found that HIV-1 initiates apoptosis of cardiomyocytes through caspase-9 activation, preferentially via the intrinsic or mitochondrial initiated pathway. CXCR4 receptor-using viruses were stronger inducers of apoptosis than CCR5 utilizing variants. Importantly, we discovered that HIV-1 induced apoptosis of cardiomyocytes was mitigated by UCLA1. However, UCLA1 had no protective effective on cardiomyocytes when apoptosis was triggered by HIV-infected MDM. When HIV-1 was treated with UCLA1 prior to infection of MDM, it failed to induce apoptosis of cardiomyocytes. These data suggest that HIV-1 causes a mitochondrial initiated apoptotic cascade, which signal through caspase-9, whereas HIV-1 infected MDM causes apoptosis predominantly via the death-receptor pathway, mediated by caspase-8. Furthermore the data suggest that UCLA1 protects cardiomyocytes from caspase-mediated apoptosis, directly by binding to HIV-1 and indirectly by preventing infection of MDM.

The long-term cumulative cytotoxicity of antiretrovirals (ARVs) is among the major causes of treatment failure in patients infected with human immunodeficiency virus (HIV) and patients with AIDS. This calls for the development of novel ARVs with less or no cytotoxicity. In the present study, we compared the cytotoxic effects of a cross-clade HIV type 1-neutralizing aptamer called B40 with those of a panel of nonnucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors (PIs), and the entry inhibitor (EI) T20 in human cardiomyocytes and peripheral blood mononuclear cells. An initial screen in which cell death was used as the end-point measurement revealed that the B40 aptamer and T20 were the only test molecules that had insignificant (0.61 < P < 0.92) effects on the viability of both cell types at the maximum concentration used. PIs were the most toxic class (0.001 < P < 0.00001), followed by NNRTIs and NRTIs (0.1 < P < 0.00001). Further studies revealed that B40 and T20 did not interfere with the cellular activity of the cytochrome P450 3A4 enzyme (0.78 < P < 0.24) or monoamine oxidases A and B (0.83 < P < 0.56) when the activities of the enzymes were compared to those in untreated controls of both cell types. Mitochondrion-initiated cellular toxicity is closely associated with the use of ARVs. Therefore, we used real-time PCR to quantify the relative ratio of mitochondrial DNA to nuclear DNA as a marker of toxicity. The levels of mitochondrial DNA remained unchanged in cells exposed to the B40 aptamer compared to the levels in untreated control cells (0.5 > P > 0.06). These data support the development of B40 and related EI aptamers as new ARVs with no cytotoxicity at the estimated potential therapeutic dose.