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CETP activity reduces plasma HDL-cholesterol concentrations, a correlate of an increased risk of atherosclerotic events. However, our recent findings suggest that CETP expression in macrophages promotes an intracellular antioxidant state, reduces free cholesterol accumulation and phagocytosis, and attenuates pro-inflammatory gene expression. To determine whether CETP expression in macrophages affects atherosclerosis development, we transplanted bone marrow from transgenic mice expressing simian CETP or non-expressing littermates into hypercholesterolemic LDL-receptor-deficient mice. The CETP expression did not change the lipid-stained lesion areas but decreased the macrophage content (CD68), neutrophil accumulation (LY6G), and TNF-α aorta content of young male transplanted mice and decreased LY6G, TNF-α, iNOS, and nitrotyrosine (3-NT) in aged female transplanted mice. These findings suggest that CETP expression in bone-marrow-derived cells reduces the inflammatory features of atherosclerosis. These novel mechanistic observations may help to explain the failure of CETP inhibitors in reducing atherosclerotic events in humans.
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Aterosclerose , Medula Óssea , Humanos , Camundongos , Animais , Masculino , Feminino , Idoso , Medula Óssea/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Proteínas de Transferência de Ésteres de Colesterol/genética , Proteínas de Transferência de Ésteres de Colesterol/metabolismo , Aterosclerose/metabolismo , Colesterol/metabolismo , Camundongos Transgênicos , Camundongos Endogâmicos C57BLRESUMO
Endothelial dysfunction is an early manifestation of atherosclerosis. The cholesteryl ester transfer protein (CETP) has been considered proatherogenic by reducing plasma HDL levels. However, CETP may exhibit cell- or tissue-specific effects. We have previously reported that male mice expressing the human CETP gene show impaired endothelium-mediated vascular relaxation associated with oxidative stress. Although sexual dimorphisms on the metabolic role of CETP have been proposed, possible sex differences in the vascular effects of CETP were not previously studied. Thus, here we investigated the endothelial function of female CETP transgenic mice as compared with nontransgenic controls (NTg). Aortas from CETP females presented preserved endothelium-dependent relaxation to acetylcholine and an endothelium-dependent reduction of phenylephrine-induced contraction. eNOS phosphorylation (Ser1177) and calcium-induced NO levels were enhanced, whereas reactive oxygen species (ROS) production and NOX2 and SOD2 expression were reduced in the CETP female aortas. Furthermore, CETP females exhibited increased aortic relaxation to 17ß-estradiol (E2) and upregulation of heat shock protein 90 (HSP90) and caveolin-1, proteins that stabilize estrogen receptor (ER) in the caveolae. Indeed, CETP females showed an increased E2-induced relaxation in a manner sensitive to estrogen receptor-α (ERα) and HSP90 inhibitors methylpiperidinopyrazole (MPP) and geldanamycin, respectively. MPP also impaired the relaxation response to acetylcholine in CETP but not in NTg females. Altogether, the study indicates that CETP expression ameliorates the anticontractile endothelial effect and relaxation to E2 in females. This was associated with less ROS production, and increased eNOS-NO and E2-ERα pathways. These results highlight the need for considering the sex-specific effects of CETP on cardiovascular risk.NEW & NOTEWORTHY Here we demonstrated that CETP expression has a sex-specific impact on the endothelium function. Contrary to what was described for males, CETP-expressing females present preserved endothelium-dependent relaxation to acetylcholine and improved relaxation response to 17ß-estradiol. This was associated with less ROS production, increased eNOS-derived NO, and increased expression of proteins that stabilize estrogen receptor-α (ERα), thus increasing E2-ERα signaling sensitivity. These results highlight the need for considering the sex-specific effects of CETP on cardiovascular risk.
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Proteínas de Transferência de Ésteres de Colesterol , Receptor alfa de Estrogênio , Óxido Nítrico Sintase Tipo III , Animais , Feminino , Camundongos , Acetilcolina/farmacologia , Proteínas de Transferência de Ésteres de Colesterol/genética , Endotélio/metabolismo , Endotélio Vascular/metabolismo , Estradiol/farmacologia , Receptor alfa de Estrogênio/genética , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Espécies Reativas de Oxigênio/metabolismo , VasodilataçãoRESUMO
AIMS: Considering the inconsistencies in the literature on the atorvastatin effect on blood pressure (BP), we performed these meta-analyses. METHODS AND RESULTS: Through a search of the Excerpta Medica Database (EMBASE), PubMed, and Web of Science databases, 1412 articles were identified, from which 33 randomized clinical trials (RCT) and 44 pre-clinical were selected. Populations from RCT were stratified according to baseline BP and lipid levels. We performed meta-analyses of the effect of atorvastatin on systolic (SBP), diastolic and mean BP; heart rate (HR); HR variability, and baroreflex. Atorvastatin reduced SBP in the overall population (P = 0.05 vs. placebo; P = 0.03 vs. baseline), in normotensive and hyperlipidaemic (P = 0.04 vs. placebo; P = 0.0001 vs. baseline) and in hypertensive and hyperlipidaemic (P = 0.02 vs. placebo; P = 0.008 vs. baseline) individuals in parallel RCT, but it did not affect SBP in normotensive and normolipidaemic individuals (P = 0.51 vs. placebo; P = 0.4 vs. baseline). Although an effect of atorvastatin was detected in hyperlipidaemic individuals, the meta-regression coefficient for the association of low density lipoprotein (LDL)-cholesterol reduction with SBP reduction in the overall population demonstrated that SBP reduction is not dependent on the changes in LDL-cholesterol. A meta-analysis of preclinical reports demonstrated that SBP was reduced in atorvastatin-treated hypertensive and normolipidaemic rats (spontaneously hypertensive rats: P < 0.00001), but not in normotensive and normolipidaemic rats (control rats: P = 0.97). Atorvastatin also reduced the HR in spontaneously hypertensive rat. CONCLUSION: Atorvastatin lowers BP independent of LDL-cholesterol levels. Additional studies are needed to estimate the involvement of the autonomic nervous system in the BP-lowering effect of atorvastatin.
Assuntos
Hipertensão , Humanos , Ratos , Animais , Atorvastatina/farmacologia , Atorvastatina/uso terapêutico , Pressão Sanguínea , Frequência Cardíaca , Hipertensão/tratamento farmacológico , ColesterolRESUMO
Plasma cholesteryl ester transfer protein (CETP) activity diminishes HDL-cholesterol levels and thus may increase atherosclerosis risk. Experimental evidence suggests CETP may also exhibit anti-inflammatory properties, but local tissue-specific functions of CETP have not yet been clarified. Since oxidative stress and inflammation are major features of atherogenesis, we investigated whether CETP modulates macrophage oxidant production, inflammatory and metabolic profiles. Comparing macrophages from CETP-expressing transgenic mice and non-expressing littermates, we observed that CETP expression reduced mitochondrial superoxide anion production and H2O2 release, increased maximal mitochondrial respiration rates, and induced elongation of the mitochondrial network and expression of fusion-related genes (mitofusin-2 and OPA1). The expression of pro-inflammatory genes and phagocytic activity were diminished in CETP-expressing macrophages. In addition, CETP-expressing macrophages had less unesterified cholesterol under basal conditions and after exposure to oxidized LDL, as well as increased HDL-mediated cholesterol efflux. CETP knockdown in human THP1 cells increased unesterified cholesterol and abolished the effects on mitofusin-2 and TNFα. In summary, the expression of CETP in macrophages modulates mitochondrial structure and function to promote an intracellular antioxidant state and oxidative metabolism, attenuation of pro-inflammatory gene expression, reduced cholesterol accumulation, and phagocytosis. These localized functions of CETP may be relevant for the prevention of atherosclerosis and other inflammatory diseases.
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Significance: Altered plasma triglyceride metabolism and changes in dietary fatty acid types and levels are major contributors to the development of metabolic and cardiovascular diseases such as fatty liver disease, obesity, diabetes, and atherosclerosis. Lipid accumulation in visceral adipose tissue and ectopically in other organs, as well as lipid-induced redox imbalance, is connected to mitochondrial dysfunction in a range of oxidative stress-associated metabolic and degenerative disorders. Recent Advances: Successful mitochondrial adaptive responses in the context of hypertriglyceridemia and dietary bioactive polyunsaturated fatty acids contribute to increase body energy expenditure and reduce oxidative stress, thus allowing several cell types to cope with metabolic challenges and stresses. These responses include mitochondrial redox signaling, mild uncoupling, and changes in network dynamic behavior. Critical Issues: Mitochondrial bioenergetics and redox changes in a lipid overload context are relatively well characterized. However, the turning point between adaptive and maladaptive mitochondrial responses remains a critical issue to be elucidated. In addition, the relationship between changes in fusion/fission machinery and mitochondrial function is less well understood. Future Directions: The effective mitochondrial responses described here support the research for new drug design and diet or nutraceutical formulations targeting mitochondrial mild uncoupling and effective quality control as putative strategies for cardiometabolic diseases. Antioxid. Redox Signal. 36, 953-968.
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Hipertrigliceridemia , Mitocôndrias , Respiração Celular , Metabolismo Energético , Humanos , Hipertrigliceridemia/metabolismo , Lipídeos/farmacologia , Mitocôndrias/metabolismoRESUMO
Endothelial dysfunction precedes atherosclerosis and is an independent predictor of cardiovascular events. Cholesterol levels and oxidative stress are key contributors to endothelial damage, whereas high levels of plasma high-density lipoproteins (HDL) could prevent it. Cholesteryl ester transfer protein (CETP) is one of the most potent endogenous negative regulators of HDL-cholesterol. However, whether and to what degree CETP expression impacts endothelial function, and the molecular mechanisms underlying the vascular effects of CETP on endothelial cells, have not been addressed. Acetylcholine-induced endothelium-dependent relaxation of aortic rings was impaired in human CETP-expressing transgenic mice, compared to their non-transgenic littermates. However, endothelial nitric oxide synthase (eNOS) activation was enhanced. The generation of superoxide and hydrogen peroxide was increased in aortas from CETP transgenic mice, while silencing CETP in cultured human aortic endothelial cells effectively decreased oxidative stress promoted by all major sources of ROS: mitochondria and NOX2. The endoplasmic reticulum stress markers, known as GADD153, PERK, and ARF6, and unfolded protein response effectors, were also diminished. Silencing CETP reduced endothelial tumor necrosis factor (TNF) α levels, intercellular cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) expression, diminishing monocyte adhesion. These results support the notion that CETP expression negatively impacts endothelial cell function, revealing a new mechanism that might contribute to atherosclerosis.
Assuntos
Proteínas de Transferência de Ésteres de Colesterol/metabolismo , Células Endoteliais/metabolismo , Endotélio Vascular/patologia , Endotélio Vascular/fisiopatologia , Estresse Oxidativo , Animais , Caveolinas/metabolismo , Moléculas de Adesão Celular/metabolismo , Proteínas de Transferência de Ésteres de Colesterol/antagonistas & inibidores , Proteínas de Transferência de Ésteres de Colesterol/genética , Estresse do Retículo Endoplasmático , Ativação Enzimática , Humanos , Camundongos Transgênicos , NADPH Oxidases/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Fosforilação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Células THP-1 , VasodilataçãoRESUMO
OBJECTIVE: The systemic function of CETP has been well characterized. CETP plasma activity reduces HDL cholesterol and thus increases the risk of atherosclerosis. Here, we investigated whether CETP expression modulate adiposity. METHODS: Body adiposity and energy metabolism related assays and gene/protein expression were compared in CETP transgenic and non-transgenic mice and in hamsters treated with CETP neutralizing antibody. RESULTS: We found that transgenic mice expressing human CETP present less white adipose tissue mass and lower leptinemia than nontransgenic (NTg) littermates. No differences were found in physical activity, food intake, fat fecal excretion, lipogenesis or exogenous lipid accumulation in adipose depots. Nonetheless, adipose lipolysis rates and whole-body energy expenditure were elevated in CETP mice. In accordance, lipolysis-related gene expression and protein content were increased in visceral and brown adipose tissue (BAT). In addition, we verified increased BAT temperature and oxygen consumption. These results were confirmed in two other animal models: 1) hamsters treated with CETP neutralizing antibody and 2) an independent line of transgenic mice expressing simian CETP. CONCLUSIONS: These findings reveal a novel anti-adipogenic role for CETP.
Assuntos
Tecido Adiposo Marrom/metabolismo , Adiposidade/fisiologia , Proteínas de Transferência de Ésteres de Colesterol/metabolismo , Lipólise/fisiologia , Fígado/metabolismo , Animais , Anticorpos Neutralizantes , Proteínas de Transferência de Ésteres de Colesterol/genética , Cricetinae , Ingestão de Alimentos/fisiologia , Metabolismo Energético/fisiologia , Leptina/sangue , Camundongos , Camundongos Transgênicos , Atividade Motora/fisiologiaRESUMO
An early event in atherogenesis is the recruitment and infiltration of circulating monocytes and macrophage activation in the subendothelial space. Atherosclerosis subsequently progresses as a unresolved inflammatory disease, particularly in hypercholesterolemic conditions. Although physical exercise training has been a widely accepted strategy to inhibit atherosclerosis, its impact on arterial wall inflammation and macrophage phenotype and function has not yet been directly evaluated. Thus, the aim of this study was to investigate the effects of aerobic exercise training on the inflammatory state of atherosclerotic lesions with a focus on macrophages. Hypercholesterolemic LDL-receptor-deficient male mice were subjected to treadmill training for 8 weeks and fed a high-fat diet. Analyses included plasma lipoprotein and cytokine levels; aortic root staining for lipids (oil red O); macrophages (CD68, MCP1 and IL1ß); oxidative (nitrotyrosine and, DHE) and endoplasmic reticulum (GADD) stress markers. Primary bone marrow-derived macrophages (BMDM) were assayed for migration activity, motility phenotype (Rac1 and F-actin) and inflammation-related gene expression. Plasma levels of HDL cholesterol were increased, while levels of proinflammatory cytokines (TNFa, IL1b, and IL6) were markedly reduced in the exercised mice. The exercised mice developed lower levels of lipid content and inflammation in atherosclerotic plaques. Additionally, lesions in the exercised mice had lower levels of oxidative and ER stress markers. BMDM isolated from the exercised mice showed a marked reduction in proinflammatory cytokine gene expression and migratory activity and a disrupted motility phenotype. More importantly, bone marrow from exercised mice transplanted into sedentary mice led to reduced atherosclerosis in the recipient sedentary mice, thus suggesting that epigenetic mechanisms are associated with exercise. Collectively, the presented data indicate that exercise training prevents atherosclerosis by inhibiting bone marrow-derived macrophage recruitment and activation.
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In this chapter, we present the major advances in CETP research since the detection, isolation, and characterization of its activity in the plasma of humans and several species. Since CETP is a major modulator of HDL plasma levels, the clinical importance of CETP activity was recognized very early. We describe the participation of CETP in reverse cholesterol transport, conflicting results in animal and human genetic studies, possible new functions of CETP, and the results of the main clinical trials on CETP inhibition. Despite major setbacks in clinical trials, the hypothesis that CETP inhibitors are anti-atherogenic in humans is still being tested.
Assuntos
Doenças Cardiovasculares , Proteínas de Transferência de Ésteres de Colesterol , Metabolismo dos Lipídeos , Animais , Aterosclerose , Transporte Biológico , HumanosRESUMO
The atherosclerosis prone LDL receptor knockout mice (Ldlr-/-, C57BL/6J background) carry a deletion of the NADP(H)-transhydrogenase gene (Nnt) encoding the mitochondrial enzyme that catalyzes NADPH synthesis. Here we hypothesize that both increased NADPH consumption (due to increased steroidogenesis) and decreased NADPH generation (due to Nnt deficiency) in Ldlr-/- mice contribute to establish a macrophage oxidative stress and increase atherosclerosis development. Thus, we compared peritoneal macrophages and liver mitochondria from three C57BL/6J mice lines: Ldlr and Nnt double mutant, single Nnt mutant and wild-type. We found increased oxidants production in both mitochondria and macrophages according to a gradient: double mutant > single mutant > wild-type. We also observed a parallel up-regulation of mitochondrial biogenesis (PGC1a, TFAM and respiratory complexes levels) and inflammatory (iNOS, IL6 and IL1b) markers in single and double mutant macrophages. When exposed to modified LDL, the single and double mutant cells exhibited significant increases in lipid accumulation leading to foam cell formation, the hallmark of atherosclerosis. Nnt deficiency cells showed up-regulation of CD36 and down-regulation of ABCA1 transporters what may explain lipid accumulation in macrophages. Finally, Nnt wild-type bone marrow transplantation into LDLr-/- mice resulted in reduced diet-induced atherosclerosis. Therefore, Nnt plays a critical role in the maintenance of macrophage redox, inflammatory and cholesterol homeostasis, which is relevant for delaying the atherogenesis process.
Assuntos
Aterosclerose/metabolismo , Macrófagos Peritoneais/metabolismo , NADP/metabolismo , Estresse Oxidativo , Transportador 1 de Cassete de Ligação de ATP/genética , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Animais , Aterosclerose/induzido quimicamente , Aterosclerose/genética , Biomarcadores , Antígenos CD36/metabolismo , Dieta Hiperlipídica , Regulação da Expressão Gênica , Genótipo , Glutationa/metabolismo , Inflamação , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Mutação , NADP Trans-Hidrogenases , Receptores de LDL/genética , Superóxidos/metabolismoRESUMO
BACKGROUND: HMG-CoA reductase inhibitors (statins) are cholesterol-lowering drugs widely used to treat hypercholesterolemia and prevent cardiovascular disease. Statins are generally well tolerated, but adverse reactions may occur, particularly myopathy and new onset of diabetes. The exact mechanism of statin-induced myopathy and diabetes has not been fully elucidated. We have previously shown that treatment of hypercholesterolemic (LDLr-/-) mice with pravastatin for 2 months decreased pancreatic islet insulin secretion and increased oxidative stress and cell death, but no glucose intolerance was observed. The purpose of the current work was to study long-term pravastatin effects on glucose homeostasis, insulin sensitivity, muscle protein turnover and cell viability. METHODS: LDLr-/- mice were treated with pravastatin for 3, 6 and 10 months. Glucose tolerance, insulin resistance and glucose-stimulated insulin secretion were evaluated. The rates of protein synthesis and degradation were determined in gastrocnemius muscle after 10 months of treatment. Insulin signalling, oxidative stress and cell death were analysed in vitro using C2C12 myotubes. RESULTS: After 6 and 10 months of treatment, these mice became glucose intolerant, and after 10 months, they exhibited marked insulin resistance. Reduced islet glucose-stimulated insulin secretion was observed after the 3rd month of treatment. Mice treated for 10 months showed significantly decreased body weight and increased muscle protein degradation. In addition, muscle chymotrypsin-like proteasomal activity and lysosomal cathepsin were markedly elevated. C2C12 myotubes exposed to increasing concentrations of pravastatin presented dose-dependent impairment of insulin-induced Akt phosphorylation, increased apoptotic markers (Bax protein and cleaved caspase-3) and augmented superoxide anion production. CONCLUSIONS: In addition to reduced insulin secretion, long-term pravastatin treatment induces insulin resistance and muscle wasting. These results suggest that the diabetogenic effect of statins is linked to the appearance of myotoxicity induced by oxidative stress, impaired insulin signalling, proteolysis and apoptosis.
Assuntos
Diabetes Mellitus Experimental/complicações , Hipercolesterolemia/complicações , Resistência à Insulina , Miotoxicidade/complicações , Pravastatina/efeitos adversos , Animais , Apoptose , Glicemia/metabolismo , Peso Corporal , Linhagem Celular , Diabetes Mellitus Experimental/sangue , Jejum/sangue , Feminino , Intolerância à Glucose/sangue , Intolerância à Glucose/complicações , Homeostase , Hipercolesterolemia/sangue , Insulina/sangue , Secreção de Insulina , Camundongos Endogâmicos C57BL , Modelos Biológicos , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Proteínas Musculares/metabolismo , Miotoxicidade/sangue , Estresse Oxidativo , Fosforilação , Proteólise , Receptores de LDL/deficiência , Receptores de LDL/metabolismo , Transdução de Sinais , Superóxidos/metabolismoRESUMO
New onset of diabetes is associated with the use of statins. We have recently demonstrated that pravastatin-treated hypercholesterolemic LDL receptor knockout (LDLr-/- ) mice exhibit reductions in insulin secretion and increased islet cell death and oxidative stress. Here, we hypothesized that these diabetogenic effects of pravastatin could be counteracted by treatment with the antioxidant coenzyme Q 10 (CoQ 10 ), an intermediate generated in the cholesterol synthesis pathway. LDLr -/- mice were treated with pravastatin and/or CoQ 10 for 2 months. Pravastatin treatment resulted in a 75% decrease of liver CoQ 10 content. Dietary CoQ 10 supplementation of pravastatin-treated mice reversed fasting hyperglycemia, improved glucose tolerance (20%) and insulin sensitivity (>2-fold), and fully restored islet glucose-stimulated insulin secretion impaired by pravastatin (40%). Pravastatin had no effect on insulin secretion of wild-type mice. In vitro, insulin-secreting INS1E cells cotreated with CoQ 10 were protected from cell death and oxidative stress induced by pravastatin. Simvastatin and atorvastatin were more potent in inducing dose-dependent INS1E cell death (10-15-fold), which were also attenuated by CoQ 10 cotreatment. Together, these results demonstrate that statins impair ß-cell redox balance, function and viability. However, CoQ 10 supplementation can protect the statins detrimental effects on the endocrine pancreas.
Assuntos
Hipercolesterolemia/tratamento farmacológico , Células Secretoras de Insulina/efeitos dos fármacos , Pravastatina/efeitos adversos , Receptores de LDL/metabolismo , Ubiquinona/análogos & derivados , Animais , Linhagem Celular , Sobrevivência Celular , Diabetes Mellitus/induzido quimicamente , Suplementos Nutricionais , Feminino , Teste de Tolerância a Glucose , Peróxido de Hidrogênio , Insulina , Fígado/metabolismo , Camundongos , Camundongos Knockout , Pravastatina/uso terapêutico , Receptores de LDL/genética , Ubiquinona/farmacologiaRESUMO
Statins are the preferred therapy to treat hypercholesterolemia. Their main action consists of inhibiting the cholesterol biosynthesis pathway. Previous studies report mitochondrial oxidative stress and membrane permeability transition (MPT) of several experimental models submitted to diverse statins treatments. The aim of the present study was to investigate whether chronic treatment with the hydrophilic pravastatin induces hepatotoxicity in LDL receptor knockout mice (LDLr-/-), a model for human familial hypercholesterolemia. We evaluated respiration and reactive oxygen production rates, cyclosporine-A sensitive mitochondrial calcium release, antioxidant enzyme activities in liver mitochondria or homogenates obtained from LDLr-/- mice treated with pravastatin for 3 months. We observed that pravastatin induced higher H2O2 production rate (40%), decreased activity of aconitase (28%), a superoxide-sensitive Krebs cycle enzyme, and increased susceptibility to Ca2+-induced MPT (32%) in liver mitochondria. Among several antioxidant enzymes, only glucose-6-phosphate dehydrogenase (G6PD) activity was increased (44%) in the liver of treated mice. Reduced glutathione content and reduced to oxidized glutathione ratio were increased in livers of pravastatin treated mice (1.5- and 2-fold, respectively). The presence of oxidized lipid species were detected in pravastatin group but protein oxidation markers (carbonyl and SH- groups) were not altered. Diet supplementation with the antioxidants CoQ10 or creatine fully reversed all pravastatin effects (reduced H2O2 generation, susceptibility to MPT and normalized aconitase and G6PD activity). Taken together, these results suggest that 1- pravastatin induces liver mitochondrial redox imbalance that may explain the hepatic side effects reported in a small number of patients, and 2- the co-treatment with safe antioxidants neutralize these side effects.
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Mitochondrial redox imbalance and high Ca2+ uptake induce the opening of the permeability transition pore (PTP) that leads to disruption of energy-linked mitochondrial functions and triggers cell death in many disease states. In this review, we discuss the major results from our studies investigating the consequences of NAD(P)-transhydrogenase (NNT) deficiency, and of statins treatment for mitochondrial functions and susceptibility to Ca2+ -induced PTP. We highlight the aggravation of high fat diet-induced fatty liver disease in the context of NNT deficiency and the role of antioxidants in the prevention of statins toxicity to mitochondria.
Assuntos
Cálcio/metabolismo , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , NADP Trans-Hidrogenases/genética , Animais , Dieta Hiperlipídica , Fígado Gorduroso/tratamento farmacológico , Fígado Gorduroso/etiologia , Fígado Gorduroso/veterinária , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Mitocôndrias/efeitos dos fármacos , Poro de Transição de Permeabilidade Mitocondrial , NADP Trans-Hidrogenases/metabolismo , Permeabilidade/efeitos dos fármacos , Ubiquinona/análogos & derivados , Ubiquinona/química , Ubiquinona/metabolismoRESUMO
Cardiovascular diseases are major causes of death worldwide. Beyond the classical cholesterol risk factor, other conditions such as oxidative stress are well documented to promote atherosclerosis. The Mangifera indica L. extract (Vimang®) was reported to present antioxidant and hypocholesterolemic properties. Thus, here we evaluate the effects of Vimang treatment on risk factors of the atherosclerosis prone model of familial hypercholesterolemia, the LDL receptor knockout mice. Mice were treated with Vimang during 2 weeks and were fed a cholesterol-enriched diet during the second week. The Vimang treated mice presented significantly reduced levels of plasma (15%) and liver (20%) cholesterol, increased plasma total antioxidant capacity (10%) and decreased reactive oxygen species (ROS) production by spleen mononuclear cells (50%), P < 0.05 for all. In spite of these benefits, the average size of aortic atherosclerotic lesions stablished in this short experimental period did not change significantly in Vimang treated mice. Therefore, in this study we demonstrated that Vimang has protective effects on systemic and tissue-specific risk factors, but it is not sufficient to promote a reduction in the initial steps of atherosclerosis development. In addition, we disclosed a new antioxidant target of Vimang, the spleen mononuclear cells that might be relevant for more advanced stages of atherosclerosis.
Assuntos
Colesterol/sangue , Mangifera/química , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Receptores de LDL/genética , Animais , Aorta/patologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Aterosclerose/veterinária , Colesterol/análise , Dieta Hiperlipídica , Leucócitos/citologia , Leucócitos/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Mangifera/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , NADP/química , NADP/metabolismo , Extratos Vegetais/química , Espécies Reativas de Oxigênio/metabolismo , Receptores de LDL/deficiência , Triglicerídeos/análise , Triglicerídeos/sangueRESUMO
This commentary introduces the subject, the context and the history of the Brazilian annually held meeting on Mitochondrial Research by the occasion of its 10th anniversary. Mitomeetings gather people interested in all aspects of mitochondrial biology in diverse species, including protists, animals, plants, and fungi.
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Mitocôndrias/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Aniversários e Eventos Especiais , Brasil , Fungos/metabolismo , Plantas/metabolismoRESUMO
Ageing and atherosclerosis are associated with oxidative stress. Mitochondrial redox function declines with ageing. Here we tested whether ageing LDL receptor knockout mice (LDLr-/-) develop spontaneous atherosclerosis and whether mitochondrial reactive oxygen species (mtROS) correlate with atherosclerosis. Compared with young mice, aged LDLr-/- mice exhibited 20-fold larger aortic lesion size, although the plasma cholesterol levels did not vary between age groups. The lesion sizes increased exponentially from 3 to 24months of age (r=0.92, p=0.0001) and were correlated with mtROS across the age range (r=0.81, p=0.0001). Thus, LDLr-/- mice develop spontaneous diet-independent atherosclerosis, that advances exponentially with ageing. We propose that age related increases in mtROS contribute to accelerate atherosclerosis development in hypercholesterolemic mice.
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Envelhecimento , Aterosclerose/etiologia , Hipercolesterolemia/complicações , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Masculino , Camundongos , Camundongos Knockout , Receptores de LDL/fisiologiaRESUMO
The mechanisms by which a high fat diet (HFD) promotes non-alcoholic fatty liver disease (NAFLD) appear to involve liver mitochondrial dysfunctions and redox imbalance. We hypothesized that a HFD would increase mitochondrial reliance on NAD(P)-transhydrogenase (NNT) as the source of NADPH for antioxidant systems that counteract NAFLD development. Therefore, we studied HFD-induced liver mitochondrial dysfunctions and NAFLD in C57Unib.B6 congenic mice with (Nnt+/+) or without (Nnt-/-) NNT activity; the spontaneously mutated allele (Nnt-/-) was inherited from the C57BL/6J mouse substrain. After 20 weeks on a HFD, Nnt-/- mice exhibited a higher prevalence of steatohepatitis and content of liver triglycerides compared to Nnt+/+ mice on an identical diet. Under a HFD, the aggravated NAFLD phenotype in the Nnt-/- mice was accompanied by an increased H2O2 release rate from mitochondria, decreased aconitase activity (a redox-sensitive mitochondrial enzyme) and higher susceptibility to Ca2+-induced mitochondrial permeability transition. In addition, HFD led to the phosphorylation (inhibition) of pyruvate dehydrogenase (PDH) and markedly reduced the ability of liver mitochondria to remove peroxide in Nnt-/- mice. Bypass or pharmacological reactivation of PDH by dichloroacetate restored the peroxide removal capability of mitochondria from Nnt-/- mice on a HFD. Noteworthy, compared to mice that were chow-fed, the HFD did not impair peroxide removal nor elicit redox imbalance in mitochondria from Nnt+/+ mice. Therefore, HFD interacted with Nnt mutation to generate PDH inhibition and further suppression of peroxide removal. We conclude that NNT plays a critical role in counteracting mitochondrial redox imbalance, PDH inhibition and advancement of NAFLD in mice fed a HFD. The present study provide seminal experimental evidence that redox imbalance in liver mitochondria potentiates the progression from simple steatosis to steatohepatitis following a HFD.
Assuntos
Peróxido de Hidrogênio/metabolismo , Mitocôndrias Hepáticas/enzimologia , NADP Trans-Hidrogenase Específica para A ou B/genética , Hepatopatia Gordurosa não Alcoólica/etiologia , Estresse Oxidativo , Complexo Piruvato Desidrogenase/metabolismo , Aconitato Hidratase/metabolismo , Animais , Dieta Hiperlipídica , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Hepáticas/metabolismo , Proteínas Mitocondriais/genética , Mutação , Hepatopatia Gordurosa não Alcoólica/enzimologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Triglicerídeos/metabolismoRESUMO
Statins are efficient cholesterol-lowering medicines utilized worldwide. However, 10% of patients suffer from adverse effects specially related to skeletal muscle function. Pro- or anti-oxidant effects of statins have been reported. Here we hypothesized that statins induce muscle mitochondrial oxidative stress leading to mitochondrial permeability transition (MPT) which may explain statin muscle toxicity. Thus, our aims were to investigate the effects of statin chronic treatment on muscle mitochondrial respiration rates, MPT and redox state indicators in the context of hypercholesterolemia. For this purpose, we studied muscle biopsies of the hypercholesterolemic LDL receptor knockout mice (LDLr-/-) treated with pravastatin during 3 months. Plantaris, but not soleus muscle of treated mice showed significant inhibition of respiration rates induced by ADP (-14%), oligomycin (-20%) or FCCP (-40%). Inhibitions of respiratory rates were sensitive to EGTA (Ca2+ chelator), cyclosporin A (MPT inhibitor), ruthenium red (inhibitor of mitochondria Ca2+ uptake) and coenzyme Q10 (antioxidant), indicating that pravastatin treatment favors Ca2+ induced MPT. Diet supplementation with creatine (antioxidant) also protected treated mice against pravastatin sensitization to Ca2+ induced MPT. Among several antioxidant enzymes analyzed, only catalase activity was increased by 30% in plantaris muscle of pravastatin treated mice. Oxidized lipids, but not proteins biomarkers were identified in treated LDLr-/- plantaris muscle. Taken together, the present results suggest that chronic pravastatin administration to a model of familial hypercholesterolemia promotes mitochondrial dysfunctions in plantaris muscle that can be counteracted by antioxidants administered either in vitro (CoQ10) or in vivo (creatine). Therefore, we propose that inhibition of muscle mitochondrial respiration by pravastatin leads to an oxidative stress that, in the presence of calcium, opens the permeability transition pore. This mitochondrial oxidative stress caused by statin treatment also signals for cellular antioxidant system responses such as catalase upregulation. These results suggest that the detrimental effects of statins on muscle mitochondria could be prevented by co-administration of a safe antioxidant such as creatine or CoQ10.
RESUMO
Nonalcoholic fatty liver disease (NAFLD) is the principal manifestation of liver disease in obesity and metabolic syndrome. By comparing hypertriglyceridemic transgenic mice expressing apolipoprotein (apo) CIII with control nontransgenic (NTg) littermates, we demonstrated that overexpression of apoCIII, independent of a high-fat diet (HFD), produces NAFLD-like features, including increased liver lipid content; decreased antioxidant power; increased expression of TNFα, TNFα receptor, cleaved caspase-1, and interleukin-1ß; decreased expression of adiponectin receptor-2; and increased cell death. This phenotype is aggravated and additional NAFLD features are differentially induced in apoCIII mice fed a HFD. HFD induced glucose intolerance together with increased gluconeogenesis, indicating hepatic insulin resistance. Additionally, the HFD led to marked increases in plasma TNFα (8-fold) and IL-6 (60%) in apoCIII mice. Cell death signaling (Bax/Bcl2), effector (caspase-3), and apoptosis were augmented in apoCIII mice regardless of whether a HFD or a low-fat diet was provided. Fenofibrate treatment reversed several of the effects associated with diet and apoCIII expression but did not normalize inflammatory traits even when liver lipid content was fully corrected. These results indicate that apoCIII and/or hypertriglyceridemia plays a major role in liver inflammation and cell death, which in turn increases susceptibility to and the severity of diet-induced NAFLD.