Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

As the HIV-positive population ages, managing non-AIDS-related comorbidities such as cardiovascular disease (CVD) complicates HIV care. Effectively treating risk factors for CVD will help reduce its burden in the HIV-infected population. However, the evidence base for the efficacy of statins as lipid-lowering therapies in HIV-infected patients has yet to be synthesized. Most trials do not compare statins directly to each other. In the absence of head-to-head evidence, the relative treatment effects of different statins can be indirectly obtained through a network meta-analysis (NMA). This NMA aims to evaluate the use of statins for treating dyslipidemia in HIV-infected individuals. Bayesian methods were used for obtaining treatment effect estimates and probabilistic rankings of treatments. Among lipid-lowering therapies, statins were most effective in treating dyslipidemia. All statins were found to offer the same treatment benefits. To our knowledge, this is the first NMA on this topic. It provides clinicians, health economists, and policy decision-makers with precise and reliable estimates for making definitive recommendations for the use of statins in dyslipidemic HIV-positive patients.

Background The role of statins in patients with heart failure (HF) of different levels of left ventricular ejection fraction (LVEF) remains unclear especially in the light of the absence of prospective data from randomized controlled trials (RCTs) in non-ischemic HF, and taking into account potential statins’ prosarcopenic effects. We assessed the association of statin use with clinical outcomes in patients with HF. Methods We searched PubMed, EMBASE, Scopus, Google Scholar and Cochrane Central until August 2018 for RCTs and prospective cohorts comparing clinical outcomes with statin vs non-statin use in patients with HF at different LVEF levels. We followed the guidelines of the 2009 PRISMA statement for reporting and applied independent extraction by multiple observers. Meta-analyses of hazard ratios (HRs) of effects of statins on clinical outcomes used generic inverse variance method and random model effects. Clinical outcomes were all-cause mortality, cardiovascular (CV) mortality and CV hospitalization. Results Finally we included 17 studies (n = 88,100; 2 RCTs and 15 cohorts) comparing statin vs non-statin users (mean follow-up 36 months). Compared with non-statin use, statin use was associated with lower risk of all-cause mortality (HR 0.77, 95% confidence interval [CI], 0.72–0.83, P < 0.0001, I2 = 63%), CV mortality (HR 0.82, 95% CI: 0.76–0.88, P < 0.0001, I2 = 63%), and CV hospitalization (HR 0.78, 95% CI: 0.69–0.89, P = 0.0003, I2 = 36%). All-cause mortality was reduced on statin therapy in HF with both EF < 40% and ≥ 40% (HR: 0.77, 95% Cl: 0.68–0.86, P < 0.00001, and HR 0.75, 95% CI: 0.69–0.82, P < 0.00001, respectively). Similarly, CV mortality (HR 0.86, 95% CI: 0.79–0.93, P = 0.0003, and HR 0.83, 95% CI: 0.77–0.90, P < 0.00001, respectively), and CV hospitalizations (HR 0.80 95% CI: 0.64–0.99, P = 0.04 and HR 0.76 95% CI: 0.61–0.93, P = 0.009, respectively) were reduced in these EF subgroups. Significant effects on all clinical outcomes were also found in cohort studies’ analyses; the effect was also larger and significant for lipophilic than hydrophilic statins. Conclusions In conclusion, statins may have a beneficial effect on CV outcomes irrespective of HF etiology and LVEF level. Lipophilic statins seem to be much more favorable for patients with heart failure. / Revisión por pares

Statins are widely used in the treatment of atherosclerosis and hypercholesterolemia, both of which are comorbidities of obesity. However, the effects statins have on insulin homeostasis are relatively unknown and may increase one’s risk for type-II diabetes mellitus. INS-1 pancreatic β-cells, were cultured in 11 mM glucose with 25, 50, 100, 200 nM statin or without. Specifically, this study observed the effects that pitavastatin, simvastatin, lovastatin, and pravastatin have on insulin secretion, insulin content, and ROS levels. GSIS was measured after statin and non-statin exposed cells were incubated in 12 mM glucose KRB. Insulin content was measured after trypsinization and subsequent lysing of cells. Both were analyzed via FRET based HTRF assay. ROS levels within cells were measured following statin exposure during a 2-hour period of 12 mM glucose oxidation after DCF was added. Analysis was done using a Tecan™ fluorescent microplate reader. Pitavastatin, simvastatin, and lovastatin decrease glucose stimulated insulin secretion and insulin content as compared to control. All concentrations of pitavastatin reduced insulin secretion proportionally to insulin content, suggesting it does so through impairment of insulin synthesis or storage. Simvastatin reduced insulin secretion and content in a dose dependent manner, however when secretion was adjusted for % content, data showed that high doses of simvastatin reduced insulin content in a greater fashion than insulin secretion, suggesting both secretory mechanisms and storage/synthesis were impaired. Lovastatin reduced insulin secretion by a greater amount than its reduction of insulin content, suggesting that it impaired insulin secretion via secretory mechanism impairment. Pravastatin did not have an effect on either insulin secretion or insulin content at any concentration. Cells were also tested to determine if pitavastatin, simvastatin, or lovastatin induced a change in ROS levels within the cell. None of the three statins tested caused a statistically significant change in ROS levels at all concentrations. These results suggest that pitavastatin, simvastatin, and lovastatin may impair insulin secretion in patients with high blood glucose. As such, clinical guidelines for statin therapy use in those who are at risk, or suffer from, diabetes may need to be reevaluated.

As a front-line treatment for cardiovascular disease, statins are among some of the most widely prescribed drugs worldwide. Statins are effective at lowering cholesterol, but approximately 7-29% of patients report some form of adverse muscle effect during the course of treatment. The severity of these side effects ranges from low-level to life-threatening myopathy. The mechanism of statin myopathy remains ill-defined, but muscle-specific E3 ubiquitin ligases have been implicated. In addition, statins have been shown to activate caspase-1 (and increase IL-1β) in immune cells, which is a key effector of the NLRP3 inflammasome. The relevance of this inflammatory response in statin myopathy remains unknown. Using C2C12 myotubes, an in vitro model of statin-induced myopathy was developed to test the impact of NLRP3 inflammasome activation on markers of statin myopathy. Gene expression of the muscle-specific E3 ubiquitin ligases atrogin-1 and MuRF-1 (atrogenes) were used as markers of statin-induced myopathy. Lipopolysaccharide priming of the NLRP3 inflammasome was found to lower the effective dose of fluvastatin required to augment atrogene expression. This effect correlated with reduced phosphorylation of Akt and FOXO3a, a transcription factor regulating atrogene expression. Statin-induced atrogene expression was also found to be dependent on an isoprenoid that is required for protein prenylation rather than cholesterol biosynthesis pathways. Fluvastatin increased caspase-1 activity in a prenylation-dependent manner and selective inhibitors of NLRP3 and caspase-1 were able to prevent increased atrogene expression with fluvastatin treatment. Therefore, the NLRP3 inflammasome contributes to markers of statin-induced myopathy through a prenylation-dependant pathway in muscle cells. This work presents a novel mechanism involved in statin myopathy, and has shown that the inflammasome may represent a new drug target to mitigate muscle symptoms in patients taking statins. / Thesis / Master of Science (MSc) / Statins are a class of widely prescribed cholesterol-lowering drugs that reduce the risk of heart attack and stroke. However, many patients often complain of statin-induced muscle side effects (myopathy) that impact their quality of life. Symptoms of this statin-induced myopathy can manifest as muscle pain and weakness. The underlying biology causing this condition is still not well understood. Independent of its cholesterol-lowering effect, statins can activate an immune receptor called the NLRP3 inflammasome, indicating that inflammation may contribute to myopathy. Therefore, the primary goal of this study was to determine if this immune response contributes to statin-induced myopathy. It was found that inhibition of the NLRP3 inflammasome lowers markers of statin myopathy. Results from this study will provide further insight into mechanisms regulating this myopathy, and may lead to new treatments that can help alleviate statin side effects in muscle.

No description available.

Τα ευεργετικά αποτελέσματα των αναστολέων της αναγωγάσης του HMG-CoA (3-υδροξυ-3-μεθυλ-γλουταρυλ-συνένζυμο Α) έχουν αποδοθεί όχι μόνο στη μείωση των επιπέδων χοληστερόλης αλλά και στις πλειοτροπικές τους δράσεις και ιδιαίτερα στις αντιοξειδωτικές τους δράσεις. Ο Nrf2 (NF-E2-related factor 2) είναι ένας μεταγραφικός παράγοντας που ενορχηστρώνει τη μεταγραφική απάντηση των κυττάρων στο οξειδωτικό στρες και σε ηλεκτροφιλικά ξενοβιοτικά με την έκφραση αντιοξειδωτικών-κυτταροπροστατευτικών γονιδίων. Στην παρούσα μελέτη, χρησιμοποιήθηκαν επίμυες Wistar, πρωτογενείς καλλιέργειες ηπατοκυττάρων, ST-2 κύτταρα και πρωτογενείς εμβρυϊκοί ινοβλάστες από μυς C57BL6J αγρίου τύπου (WT) ή με απαλοιφή του Nrf2 (KO-Nrf2) για τη μελέτη του ρόλου του Nrf2 στη διαμεσολάβηση των αντιοξειδωτικών δράσεων των στατινών. Η σιμβαστατίνη ενεργοποίησε τον Nrf2, δηλαδή οδήγησε στη μετακίνησή του στον πυρήνα στο ήπαρ επίμυων και σε πρωτογενή καλλιέργεια ηπατοκυττάρων. Η ανωτέρω δράση ήταν εξαρτώμενη από το μεβαλονικό και ανεξάρτητη από τη χοληστερόλη. Σε πυρηνικά πρωτεϊνικά εκχυλίσματα από ήπαρ επίμυων που έλαβαν σιμβαστατίνη, η μεταγραφική ενεργότητα του Nrf2 αυξήθηκε σημαντικά και το mRNA δύο γνωστών στόχων του Nrf2, ΗΟ-1 (Heme Oxygenase 1) και GPX-2 (Glutathione Peroxidase 2) αυξήθηκε. Σε ST-2 κύτταρα μόνιμα διαμολυσμένα με πλασμίδιο που φέρει αλληλουχία DNA στην οποία προσκολλάται ο Nrf2 (ARE-Antioxidant Response Element) (ARE-ST2 κύτταρα), η σιμβαστατίνη αύξησε τη μεταγραφική ενεργότητα του Nrf2 με τρόπο εξαρτώμενο από το μεβαλονικό και ανεξάρτητο από τη χοληστερόλη. Επίσης, χρησιμοποιώντας πρωτογενείς καλλιέργειες εμβρυϊκών ινοβλαστών από μυς WT και ΚΟ-Nrf2 και μετρώντας τα επίπεδα των αντιδραστικών ειδών οξυγόνου (ROS) μετά από επώαση με οξειδάση της γλυκόζης έπειτα από επίδραση ή μη με σιμβαστατίνη, διαπιστώθηκε ότι η σιμβαστατίνη μειώνει τα επίπεδα των παραχθέντων ROS στους WT ινοβλάστες και όχι σε μεγάλο βαθμό στους KO-Nrf2 ινοβλάστες Τέλος, με τη χρήση αναστολέων του μονοπατιού της PI3K/Akt σε ARE-ST2 κύτταρα στα οποία είχαμε επιδράσει με σιμβαστατίνη, διαπιστώθηκε ότι αίρεται σε μεγάλο βαθμό η ενεργοποίηση του Nrf2 από τη σιμβαστατίνη. Στην παρούσα μελέτη παρουσιάζεται για πρώτη φορά α) η ενεργοποίηση του Keap1/Nrf2 σηματοδοτικού μονοπατιού σε in vivo και in vitro μοντέλα από τη σιμβαστατίνη με τρόπο εξαρτώμενο από το μεβαλονικό και ανεξάρτητο από τη χοληστερόλη και β) ότι η σιμβαστατίνη μειώνει τα παραγόμενα αντιδραστικά είδη οξυγόνου (ROS) μέσω της ενεργοποίησης του Nrf2 διαμέσου του μοριακού μονοπατιού της PI3K/Akt. H ενεργοποίηση αυτή του Nrf2 από τη σιμβαστατίνη εκτός του ότι προσφέρει αποτελεσματική προστασία του κυττάρου από τις δυσμενείς επιπτώσεις του οξειδωτικού στρες, εξηγεί και μέρος των πλειοτροπικών δράσεων των στατινών. / The beneficial effects of HMG-CoA (3-hydroxy-3-methyl-glutaryl-CoA) reductase inhibitors (statins) have been attributed not only to their cholesterol lowering effect but also to their pleiotropic actions and especially to their anti-oxidant activity. Nrf2 (NF-E2-related factor 2) is a transcription factor that orchestrates the transcriptional response of cells to oxidative stressors and electrophilic xenobiotics. In the present study, Wistar rats, primary hepatocytes, ST-2 cells and primary mouse embryonic fibroblasts from wild type or Nrf2 knock out C57BL6J mice were used to explore the potential role of Nrf2 in mediating the antioxidant effects of statins. Simvastatin triggered nuclear translocation of Nrf2 in rat liver and in primary rat hepatocytes in a mevalonate-dependent and cholesterol-independent way. In liver nuclear extracts from simvastatin-treated rats, the DNA-binding activity of Nrf2 was significantly increased and the mRNA of two known targets of Nrf2, HO-1 (Heme Oxygenase 1) and GPX-2 (Glutathione Peroxidase 2) was induced. In ST-2 cells (ARE-ST2) stably transfected with constructs bearing Nrf2-binding site (antioxidant responsive element), simvastatin enhanced Nrf2-mediated transcriptional activity in a mevalonate-dependent and cholesterol-independent fashion. Moreover, in WT and KO-Nrf2 primary mouse embryonic fibroblasts, after incubation with simvastatin, the addition of glucose-oxidase resulted in much greater levels of ROS (Reactive Oxygen Species) in simvastatin treated KO-Nrf2 fibroblasts compared to their WT counterparts, which means that simvastatin eliminates ROS in a Nrf2 dependent way. Finally, the use of PI3K/Akt pathway inhibitors in simvastatin treated ARE-ST2 cells leads to the attenuation of the simvastatin-induced enhanced Nrf2 transcriptional activity. In the present study, it is shown for the first time that a) simvastatin activates the Keap1/Nrf2 signaling pathway in in vivo and in vitro models in a mevalonate- dependent, cholesterol-independent fashion and b) that simvastatin lowers reactive oxygen species level by Nrf2 activation via PI3K/Akt pathway. The activation of Nrf2 by simvastatin besides providing effective protection of the cell from the deleterious effects of oxidative stress, it explains in part the pleiotropic actions of statins.

The role cholesterol plays in the brain has long been underappreciated even though the brain contains a disproportionately high percentage of body cholesterol. Recent studies have found a link between the dysregulation of lipid metabolism and the risk of acquiring Alzheimer’s disease (AD) as well as a predisposition to cognitive decline. The goal of these studies was to elucidate the possible role lipid metabolism plays in pathological and normal brain aging by pharmacologically manipulating lipid metabolism and determining effects on key hippocampal biomarkers of AD and age-related cognitive decline. One series of experiments used an agonist (TO901317) to the liver X receptor (LXR) in two transgenic AD mouse models. Chronic LXR activation reduced AD associated pathology and improved cognitive performance in AD mouse models. However, long-term potentiation (LTP) was not enhanced and peripheral side effects were observed. In another series of experiments the effects of chronically inhibiting cholesterol synthesis on cognitive aging in rats was determined. Animals were treated with either of two commonly prescribed statins, simvastatin or atorvastatin. Simvastatin, the more lipophilic statin, increased LTP and reduced the duration of the afterhyperpolarization (AHP). In addition, simvastatin upregulated key genes of the cholesterol synthesis pathway in the hippocampus as revealed by microarray analyses, but was associated with impaired performance in the Morris Water Maze, a hippocampal dependent task. Atorvastatin, a less lipophilic statin, reduced the AHP, but did not affect LTP or cognitive performance. Atorvastatin modulated a very different set of genes and reduced brain cholesterol more than simvastatin. These results suggest that manipulation of cholesterol metabolism selectively modulates key aspects of AD and brain aging.

Background: Despite substantial research and development investment in Alzheimer's disease (AD), effective therapeutics remain elusive. Significant emerging evidence has linked cholesterol, beta-amyloid and AD, and several studies have shown a reduced risk for AD and dementia in populations treated with statins. However, while some clinical trials evaluating statins in general AD populations have been conducted, these resulted in no significant therapeutic benefit. By focusing on subgroups of the AD population, it may be possible to detect endotypes responsive to statin therapy. Methods: Here we investigate the possible protective and therapeutic effect of statins in AD through the analysis of datasets of integrated clinical trials, and prospective observational studies. Results: Re-analysis of AD patient-level data from failed clinical trials suggested by trend that use of simvastatin may slow the progression of cognitive decline, and to a greater extent in ApoE4 homozygotes. Evaluation of continual long-term use of various statins, in participants from multiple studies at baseline, revealed better cognitive performance in statin users. These findings were supported in an additional, observational cohort where the incidence of AD was significantly lower in statin users, and ApoE4/ApoE4-genotyped AD patients treated with statins showed better cognitive function over the course of 10-year follow-up. Conclusions: These results indicate that the use of statins may benefit all AD patients with potentially greater therapeutic efficacy in those homozygous for ApoE4.

Seulement 1 à 3% des cas de paludisme dégénèrent en NP. Cependant, les séquelles à long termes touchent 3 à 10% des adultes et 25% des enfants et ces personnes présentent des déficits cognitifs notamment au niveau de l'apprentissage. Au niveau de l'armée française, ce sont 15 000 militaires qui sont exposés chaque année dans les zones impaludées, avec au moins 350 accès palustres mais surtout 1 à 2 morts chaque année.Dans le but de lutter contre P. falciparum mais aussi diminuer les séquelles dans le cas du NP deux molécules ont été étudiées. D'une part, l'atorvastatine (AVA) et d'autre part le bleu de méthylène (BM). Les données, précédemment publiées, ont montré l'efficacité de l'AVA non seulement comme antibactérien, antiviral ou antiparasitique mais aussi comme modulateur de l'immunité et adjuvant potentiel pour les antipaludiques actuels. Le BM est un antipaludique qui jusqu'ici présentait une voie de synthèse avec métaux lourds. C'est une nouvelle voie de synthèse sans métaux lourds et une efficacité démontrée qui nous ont incités à étudier cette molécule.Pour estimer l'efficacité de l'AVA et du BM en association avec les antipaludiques actuels nous avons successivement testé ces molécules dans un modèle in vitro (micro test isotopique simplifié) contre P. falciparum, puis dans un modèle murin de neuropaludisme en utilisant des souris C57BL/6N infectées avec Plasmodium berghei. Un gain d'efficacité a été observé en associant l'AVA ou le BM avec les antipaludiques contre P. falciparum mais aussi une protection par rapport au NP chez les souris traitées par les associations. Le BM protégeant aussi bien contre le paludisme simple que le NP. / Only 1 to 3% of malaria infections turn into CM. Meanwhile, long term neurological sequelae range from 3 to 10 % in adults and 25% of child survivors present long term cognitive impairments. In a military framework, there are 15 000 soldiers localized in endemic malaria areas, with at less 350 infection cases giving clinical malaria syndrome but mainly 2 deaths each year.In the aim to fight against P. falciparum but also to decrease sequelae related to CM, two molecules were studied. In one hand, atorvastatin (AVA) and in the other hand methylene blue (MB). AVA is a synthetic inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (3HMG-CoA) reductase used in the treatment of hypercholesterolemia. Previous data, reported in numerous articles support the efficacy of AVA not only as antimicrobial, antiviral or antiparasitic agent but also as immune system modulator and potential adjuvant in vitro for common antimalarial drugs. BM is an antimalarial drug which until now had a synthesis pathway with heavy metals. It is a new synthesis pathway without heavy metals and an efficacy demonstrated which encouraged us to study this molecule.To evaluate AVA and BM efficacies in combination with common antimalarial drugs, we successively tested these molecules in an in vitro model (simplified isotopic microtest) against P. falciparum, then in experimental cerebral malaria using C57BL/6N mice infected with Plasmodium berghei. An increased efficacy was observed when AVA or MB is associated with common antimalarial drugs against P. falciparum but also a protection against CM in mice treated by drugs combinations. MB protects against malaria but also CM.