Browsing by Author "Reyskens, Kathleen Maria Simone Elise"

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    The maladaptive effects of HIV protease inhibitors (Lopinavir/Ritonavir) on the rat heart
    (Stellenbosch : Stellenbosch University, 2013-12) Reyskens, Kathleen Maria Simone Elise; Essop, M. Faadiel; Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Although antiretroviral treatment decreases HIV-AIDS morbidity/mortality, long-term effects include onset of insulin resistance and cardiovascular diseases. Increased oxidative stress and dysregulation of the ubiquitin-proteasome system (UPS) are implicated in protease-inhibitor (PI)-mediated cardio-metabolic pathophysiology. We hypothesized that PI treatment (Lopinavir/Ritonavir) elevates myocardial oxidative stress and concomitantly inhibits the UPS, thereby attenuating cardiac function. Lopinavir/Ritonavir was dissolved in 1% ethanol (vehicle) and injected into mini-osmotic pumps that were surgically implanted into Wistar rats for eight weeks vs. vehicle and sham controls. Subsequently, we evaluated metabolic parameters and heart function (ex vivo and in vivo methods) at baseline and following ischemia-reperfusion. PI-treated rats exhibited weight gain, increased serum LDL-cholesterol, higher tissue triglycerides (heart, liver), but no evidence of insulin resistance. It also upregulated hepatic gene expression of acetyl-CoA carboxylase β and 3-hydroxy-3-methylglutaryl-CoA-reductase, key regulators of fatty acid oxidation and cholesterol synthesis, respectively. Further, PI-treated hearts displayed impaired UPS, increased superoxide dismutase (SOD) activity and unaltered superoxide levels, and elevated peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α) peptide levels. Perfusion data revealed contractile dysfunction at baseline and following ischemia-reperfusion, while post-ischemic hearts exhibited decreased ATPase specific activity vs. matched controls. Early changes initiated by PI treatment resemble the metabolic syndrome and reflect a pre-atherogenic profile. Moreover, the effects of PIs on cardiac contractile function may in part be triggered by impaired UPS activity together with strain on the mitochondrial energetic system. Our study alerts to cardio-metabolic side effects of PI treatment and raises the question of the most appropriate co-therapies for patients on chronic antiretroviral treatment.