The effects of HIV Protease Inhibitors (Lopinavir/Ritonavir) on the non-oxidative pathways of glucose metabolism

Fisher, Tarryn-Lee (2014-04)

Thesis (MSc)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: While antiretroviral therapy decreases HIV/AIDS morbidity and mortality, long-term treatment results in insulin resistance and cardiovascular diseases. A possible cause of such adverse effects may be an increase in oxidative stress resulting from protease inhibitor (PI)-induced mitochondrial dysfunction. We therefore hypothesized that PI treatment, specifically Lopinavir/Ritonavir, results in increases in myocardial reactive oxygen species (ROS), leading to downstream outcomes, i.e. elevated apoptosis. Moreover, we proposed that increased ROS levels in this instance might occur as a result of PI-mediated induction of the non-oxidative glucose pathways (NOGPs). In light of this, we also investigated the effect of PI treatment on the NOGPs by employing both in vitro and in vivo samples. For the in vitro work we employed a rat cardiomyoblast cell line, while tissues (heart, liver) were collected from two separate experimental models, i.e. a) Group A exposed to PIs via mini-osmotic pump for a period of eight weeks, and b) Group B administered PIs via a jelly-based method for 16 weeks. We found that PIs increased mitochondrial ROS levels in vitro but that this was not accompanied by a parallel rise in programmed cell death. Moreover, we found no induction of the NOGPs in response to PI exposure (for both in vitro and in vivo models here employed). However, we found that the AGE pathway was significantly down-regulated in the liver of Group A. Investigation into a proposed mechanism for this observation proved inconclusive and further studies are thus required to clarify the significance in terms of metabolic dysfunction found in the Group A model. Our study thus shows that PIs can increase ROS levels (in vitro) but that compensatory antioxidant mechanisms may prevent this in vivo. Subsequently, downstream effects were limited i.e. we did not observe NOGP induction and programmed cell death. An intriguing finding emerged, however, i.e. that PIs can elicit an impact on the AGE pathway. We propose future studies with modifications to the current rat and cell models in order to evaluate the downstream effects of PIs on the NOGPs and programmed cell death.

AFRIKAANSE OPSOMMING: Terwyl antiretrovirale terapie MIV/VIGS morbiditeit en mortaliteit verlaag, veroorsaak langtermyn behandeling insulienweerstandigheid en kardiovaskulêre siekte. 'n Moonltike oorsaak van sulke newe-effekte kan 'n toename in oksidatiewe stres veroorsaak deur die protease inhibeerder (PI)-geïnduseerde mitochondriale wanfunskionering. Ons hipotetiseer dat PI behandeling, spesifiek Lopinavir/Ritonavir, versoorsaak 'n toename in miokardiale reaktiewe suurstofspesies (ROS), wat aanleiding gee tot afstroom uitkomste, i.e. verhoogde apoptose. Verder, stel ons voor dat verhoogde ROS vlakke in hierdie geval onstaan as gevolg van PI-gemedieerde induksie van die nie-oksidatiewe glukose weë (NOGWe). In die lig hiervan het ons ook die effek van PI behandeling op die NOGWe ondersoek deur beide in vitro en in vivo monsters te gebruik. Vir die in vitro werk het ons van 'n rot kardio-mioblastsellyn gebruik gemaak, terwyl weefsels (hart, lewer) versamel is van twee afsonderlike eksperimentele modelle, i.e. a) Groep A blootgestel aan PIs via mini-osmotiese pomp vir 'n periode van agt weke, en b) Groep B PIs is toegedien via 'n jellie gebaseerde metode vir 16 weke. Ons het bevind dat die die PIs mitochondriale ROS vlakke in vitro verhoog maar dat dit nie vergesel is met 'n paralelle toename in apoptose. Verder is geen induksie van die NOGWe in reaksie op PI blootstelling waargeneem (vir beide in vitro en in vivo modelle). Hoewel ons het bevind dat die AGE weg in die lewer van Groep A beduidend afgereguleer is. Ondersoek na 'n moontlike megansime vir hierdie waarneming was onoortuigend en verdere ondersoek is nodig om die betekenis in terme van die metaboliese wanfunskionering in die Groep A model vas te stel. Ons studie toon dus aan dat PIs, ROS vlakke (in vitro) verhoog, maar dat kompensatoriese anti-oksidant meganismes in die hierdie in vivo model verhoed word. Gevolglik is die afstroom effekte beperk i.e. ons het geen NOGWe induksie en aptoptose waargeneem nie. 'n Interesante bevinding het wel uitgestaan, i.e. PIs kan 'n impak hê op die AGE weg. Ons stel dus voor dat toekomstige studies met modifikasies, tot die huidige rot- en sel-modelle gemaak word om die afstroomeffekte van PIs en apoptose te evalueer.

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