Effect of AMPK pathway on apoptosis of human thyroid papillary cancer B-CPAP cells under low glucose and hypoxia conditions through CPT1c regulated by PPARα / 中国肿瘤生物治疗杂志

@#[Abstract] Objective: To investigate the mechanisms of carnitine palmitoyltransferase 1c (CPT1c) expression to affect the proliferation and apoptosis of human thyroid papillary cancer B-CPAP cells through the AMP-dependent/activated protein kinase (AMPK) pathway in the low glucose and hypoxic conditions. Methods: Firstly,humanthyroidpapillarycarcinomaB-CPAP cells were cultured under normal condition or low glucose and hypoxic condition respectively, followed with the treatment of AMPK inhibitor compound C. Western blotting was used to detect the expressions of AMPK, p-AMPK, peroxisome proliferator-activated receptor α (PPARα) and CPT1c; the proliferation and apoptosis were detected by CCK-8 and Flow cytometry, respectively. Then PPARα-siRNA was synthesized and transfected into B-CPAP cells to knock down PPARα, and then the cells were cultured under normal or low glucose and hypoxic condition respectively.Above indicators were also detected to verify the regulation of PPARα on CPT1c. Finally, the human luciferase reporter plasmid containing CPT1c gene promoter was constructed, and the effect of PPARα on the activity of CPT1c promoter luciferase activity was observed by immunofluorescence. Results: The expressions ofAMPK, p-AMPK, PPARα and CPT1c were significantly increased in B-CPAP cells under low glucose and hypoxia condition (P<0.05 or P<0.01), while cell proliferation and apoptosis rate did not change significantly (P>0.05). After the treatment of AMPK inhibitor compound C, the expressions of p-AMPK, PPARα and CPT1c in low glucose and hypoxia group were significantly decreased (P<0.05 or P<0.01), the inhibitory rate on cell proliferation and apoptosis rate were significantly increased (P<0.05). However, the change range was smaller than that in the normal culture + compound C group (P<0.05).After PPARα knockdown, the expressions ofAMPK, p-AMPK, PPARα and CPT1c in cancer cells cultured under normal conditions were significantly decreased (P<0.05 or P<0.01), and the inhibitory rate on cell proliferation and apoptosis rate were significantly increased (P<0.05). While under low glucose and hypoxia condition, the expression of CPT1c in cells after transfection was significantly decreased (P<0.05), and the inhibition rate on cell proliferation and the apoptosis rate were significantly increased (P<0.05); However, the change range was still lower than that of normal condition group after transfection (P<0.05).After PPARα overexpression, the ratio of fluorescence in the empty vector group was not significantly different from that of the blank group (P>0.05), and the ratio of fluorescence was significantly increased in PPARα over-expression group (P<0.05). Conclusions: AMPK can increase the expression of PPARα to promote the expression of CPT1c in thyroid cancer B-CPAP cells under low glucose and hypoxia conditions, thereby inhibiting cell apoptosis and maintaining cell proliferation ability.

Deficiency or activation of peroxisome proliferator-activated receptor α reduces the tissue concentrations of endogenously synthesized docosahexaenoic acid in C57BL/6J mice

BACKGROUND/OBJECTIVES: Docosahexaenoic acid (DHA), an n-3 long chain polyunsaturated fatty acid (LCPUFA), is acquired by dietary intake or the in vivo conversion of α-linolenic acid. Many enzymes participating in LCPUFA synthesis are regulated by peroxisome proliferator-activated receptor alpha (PPARα). Therefore, it was hypothesized that the tissue accretion of endogenously synthesized DHA could be modified by PPARα. MATERIALS/METHODS: The tissue DHA concentrations and mRNA levels of genes participating in DHA biosynthesis were compared among PPARα homozygous (KO), heterozygous (HZ), and wild type (WT) mice (Exp I), and between WT mice treated with clofibrate (PPARα agonist) or those not treated (Exp II). In ExpII, the expression levels of the proteins associated with DHA function in the brain cortex and retina were also measured. An n3-PUFA depleted/replenished regimen was applied to mitigate the confounding effects of maternal DHA. RESULTS: PPARα ablation reduced the hepatic Acox, Fads1, and Fads2 mRNA levels, as well as the DHA concentration in the liver, but not in the brain cortex. In contrast, PPARα activation increased hepatic Acox, Fads1, Fads2 and Elovl5 mRNA levels, but reduced the DHA concentrations in the liver, retina, and phospholipid of brain cortex, and decreased mRNA and protein levels of the brain-derived neurotrophic factor in brain cortex. CONCLUSIONS: LCPUFA enzyme expression was altered by PPARα. Either PPARα deficiency or activation-decreased tissue DHA concentration is a stimulus for further studies to determine the functional significance.

Research advances in the role and mechanism of peroxisome proliferator-activated receptor alpha in liver diseases / 临床肝胆病杂志

Peroxisome proliferator-activated receptor alpha (PPARα) is a member of the nuclear receptor superfamily and plays a central regulatory role in lipid metabolism. Recent studies have found that PPARα agonists play a key role in the prevention and treatment of nonalcoholic fatty liver disease, which has also been reported in other liver diseases. This article reviews the role and mechanism of PPARα in nonalcoholic fatty liver disease, alcoholic liver disease, viral hepatitis, cholestatic liver disease, drug-induced liver injury, and hepatocellular carcinoma, so as to provide a reference for the research on the new application of conventional drugs associated with PPARα.

Mechanisms of PPARα,sterol regulatory element binding proteins and AMP-activated protein kinase in alcoholic fatty liver diseases:review / 中国药理学与毒理学杂志

Alcoholic fatty liver disease (AFLD) is the first step to wards alcoholic liver disease (ALD). A beffer knowledge of AFLD will contribute to the prevention and therapy of ALD. It has been found that the occurrence and development of AFLD mainly involve the pathways of cytochrome P450 (CYP2E1),peroxisome proliferator-activated receptor α(PPARα),sterol regulatory element-binding proteins (SREBPs),AMP-activated protein kinase(AMPK),sirtuin 1(SIRT1),adiponectin and insulin.This review focuses on the importance of PPARα,SREBPs and AMPK pathway in alcoholic steatosis.It's reported that alcohol and its metabolite acetaldehyde inhibit PPARα and AMPK,and activate SREBP protein directly or indirectly,leading to liver lipid metabolic disorders,reducing the ability of fatty acid oxidation,causing lipid accumulation, and eventually inducing AFLD. Additionally, this review outlines the prospect of a therapeutics of AFLD targetting PPARα,SREBPs and AMPK.

Protective Effects of Ecklonia stolonifera Extract on Ethanol-Induced Fatty Liver in Rats

Chronic alcohol consumption causes alcoholic liver disease, which is associated with the initiation of dysregulated lipid metabolism. Recent evidences suggest that dysregulated cholesterol metabolism plays an important role in the pathogenesis of alcoholic fatty liver disease. Ecklonia stolonifera (ES), a perennial brown marine alga that belongs to the family Laminariaceae, is rich in phlorotannins. Many studies have indicated that ES has extensive pharmacological effects, such as antioxidative, hepatoprotective, and antiinflammatory effects. However, only a few studies have investigated the protective effect of ES in alcoholic fatty liver. Male Sprague-Dawley rats were randomly divided into normal diet (ND) (fed a normal diet for 10 weeks) and ethanol diet (ED) groups. Rats in the ED group were fed a Lieber-DeCarli liquid diet (containing 5% ethanol) for 10 weeks and administered ES extract (50, 100, or 200 mg/kg/day), silymarin (100 mg/kg/day), or no treatment for 4 weeks. Each treatment group comprised of eight rats. The supplementation with ES resulted in decreased serum levels of triglycerides (TGs), total cholesterol, alanine aminotransferase, and aspartate aminotransferase. In addition, there were decreases in hepatic lipid and malondialdehyde levels. Changes in liver histology, as analyzed by Oil Red O staining, showed that the ES treatment suppressed adipogenesis. In addition, the ES treatment increased the expression of fatty acid oxidation-related genes (e.g., PPAR-α and CPT-1) but decreased the expression of SREBP 1, which is a TG synthesis-related gene. These results suggest that ES extract may be useful in preventing fatty acid oxidation and reducing lipogenesis in ethanol-induced fatty liver.

A Novel Cytosolic Isoform of Mitochondrial Trans-2-Enoyl-CoA Reductase Enhances Peroxisome Proliferator-Activated Receptor alpha Activity

BACKGROUND: Mitochondrial trans-2-enoyl-CoA reductase (MECR) is involved in mitochondrial synthesis of fatty acids and is highly expressed in mitochondria. MECR is also known as nuclear receptor binding factor-1, which was originally reported with yeast two-hybrid screening as a binding protein of the nuclear hormone receptor peroxisome proliferator-activated receptor alpha (PPARalpha). However, MECR and PPARalpha are localized at different compartment, mitochondria, and the nucleus, respectively. Therefore, the presence of a cytosolic or nuclear isoform of MECR is necessary for functional interaction between MECR and PPARalpha. METHODS: To identify the expression pattern of MECR and the cytosolic form of MECR (cMECR), we performed reverse transcription polymerase chain reaction (RT-PCR) with various tissue samples from Sprague-Dawley rats. To confirm the interaction between cMECR and PPARalpha, we performed several binding assays such as yeast two-hybrid, coimmunoprecipitation, and bimolecular fluorescence complementation. To observe subcellular localization of these proteins, immunocytochemistry was performed. A luciferase assay was used to measure PPARalpha activity. RESULTS: We provide evidence of an alternatively spliced variant of the rat MECR gene that yields cMECR. The cMECR lacks the N-terminal 76 amino acids of MECR and shows uniform distribution in the cytoplasm and nucleus of HeLa cells. cMECR directly bound PPARalpha in the nucleus and increased PPARalpha-dependent luciferase activity in HeLa cells. CONCLUSION: We found the cytosolic form of MECR (cMECR) was expressed in the cytosolic and/or nuclear region, directly binds with PPARalpha, and enhances PPARalpha activity.

Peroxisome Proliferator-Activated Receptor (PPAR) alpha/gamma Agonist / 대한내과학회지

Peroxisome proliferator-activated receptor (PPAR) agonists improve glucose control and insulin sensitivity, reduce concentrations of atherogenic lipoproteins, and decrease circulating levels of inflammatory mediators. PPAR activation is considered an important pharmacologic target for patients with type 2 diabetes. However, the PPAR agonists in clinical use have undesirable side effects, including weight gain, heart failure, and bone fractures. PPAR alpha/gamma dual agonists each target one or more of the key cardiometabolic risk factors of diabetic dyslipidemia, insulin resistance, hyperglycemia, and inflammation; thus, combining their benefits to provide glucose control and ameliorate cardiovascular risks has emerged as an attractive treatment option. Aleglitazar, which was designed to balance the activation of PPAR alpha/gamma, proved efficacious in improving glycemic control and lipid homeostasis and is anticipated to minimize PPAR-related side effects. Whether the effects of aleglitazar on cardiometabolic risk factors translate into improved cardiovascular outcomes, particularly in high-risk patients, is currently being evaluated by AleCardio, a large, long-term, time-, and event-driven outcome study of type 2 diabetics with recent acute coronary syndrome.

Peroxisome proliferator-activated receptor agonists (PPARs): a promising prospect in the treatment of psoriasis and psoriatic arthritis / Os receptores ativados pelo proliferador de peroxissoma (PPAR): uma perspectiva promissora na conducao da psoriase e artrite psoriasica

Psoriasis is a polygenic, inflammatory and progressive disease, characterized by an abnormal differentiation and hyperproliferation of keratinocytes, associated with impaired immunologic activation and systemic disorders, while psoriatic arthritis is a chronic inflammatory articular disease. Pathophysiology of psoriasis comprises a dysfunction of the immune system cells with an interactive network between cells and cytokines supporting the initiation and perpetuation of disease and leading to inflammation of skin, enthesis and joints. Recent studies have shown an important role of systemic inflammation in the development of atherosclerosis. Corroborating these findings, patients with severe Psoriasis have marked incidence of psoriatic arthritis, cardiovascular diseases, hypertension, dyslipidemia, obesity and diabetes mellitus, showing an increased risk for acute myocardial infarction, which suggests that the condition is not restricted to the skin. Nuclear receptors are ligand-dependent transcription factors, whose activation affects genes that control vital processes. Among them the peroxisome proliferator-activated receptor is responsible for establishing the relationship between lipids, metabolic diseases and innate immunity. In the skin, peroxisome proliferator-activated receptors have an important effect in keratinocyte homeostasis, suggesting a role in diseases such as psoriasis. The peroxisome proliferator-activated receptors agonists represent a relevant source of research in the treatment of skin conditions, however more clinical studies are needed to define the potential response of these drugs in patients with psoriasis and psoriatic arthritis.

A psoríase é uma doença poligênica, inflamatória, progressiva e recorrente, caracterizada por um ciclo evolutivo acelerado dos queratinócitos, associado à ativação imune desordenada e a alterações sistêmicas correlacionadas, sendo a artrite psoriásica o comprometimento articular inflamatório crônico que pode ocorrer em pacientes com a doença cutânea. Na inflamação autoimune, uma rede interativa entre células e citocinas suporta o início e a perpetuação da doença. A fisiopatologia da psoríase e da artrite psoriásica compreende uma disfunção das células do sistema imune e da rede de citocinas, levando à inflamação de pele, enteses e articulações. Estudos recentes têm demonstrado um papel importante da inflamação sistêmica no desenvolvimento da aterosclerose. Corroborando esses achados, pacientes portadores de psoríase grave apresentam marcada incidência de artrite psoriásica, doença cardiovascular, hipertensão arterial sistêmica, dislipidemia, obesidade e diabetes mellitus, evidenciando um risco aumentado para infarto agudo do miocárdio e sugerindo que a doença não se restringe à pele. Os receptores nucleares são fatores de transcrição ligante-dependente cuja ativação afeta genes controladores de processos vitais. Entre eles, destacam-se os receptores ativados pelo proliferador de peroxissoma, responsáveis por estabelecer a relação entre os lipídios, doenças metabólicas e imunidade inata. Na pele, os receptores ativados pelo proliferador de peroxissoma têm ação importante na homeostase dos ceratinócitos, exibindo uma função pró-diferenciação, antiproliferativa e imunomoduladora, sugerindo um papel relevante ...

Fenofibrato (agonista do receptor ativador da proliferação peroxissomal) modula o sistema renina-angiotensina no coração de camundongos alimentados com dieta hiperlipídica / Fenofibrate (peroxisome proliferator-activated receptor alpha agonist) modulates the renin-angiotensin system in the heart of mice fed with a high-fat diet

O objetivo deste trabalho foi estudar a ação do fenofibrato, um agonista do receptor ativador da proliferação peroxissomal alfa, no remodelamento cardíaco e na expressão de componentes do sistema renina-angiotensina (SRA) em um modelo de obesidade induzida por dieta. Camundongos machos C57B1/6 com três meses de idade foram alimentados durante 11 semanas com dieta controle (grupo C, 3,57 kcal/g de dieta) ou dieta hiperlipídica (grupo HL, 5,40 kcal/g de dieta), em seguida foram separados em quatro grupos e estudados durante cinco semanas: C; HO; C-L (C mais fenofibrato) e HL-F (HL mais fenofibrato). Os animais HL foram mais pesados e apresentaram maior pressão arterial (PA) comparados aos animais C, mas HL-F foram mais leves e tiveram PA menor que HL. A resistência insulínica vista nos camundongos HL foi melhorada com fenofibrato nos camundongos HL-F. Fenofibrato reduziu colesterol total, triglicerídeos e aumentou HDL-c. Os animais HL apresentou um ventrículo esquerdo (VE) mais pesado e com espessura da parede maior, como também cardiomiócitos maiores e uma menor razão cardiomiócito/capilares que os animais C. Fenofibrato foi eficiente em melhorar estas alterações. As expressões cardíacas de Angiotensina II (ANG II) e de seu receptor tipo 1 (AT1R) foram maiores, enquanto que a expressão de seu receptor tipo 2 (AT2R) foi menor nos animais HL que nos animais C, e fenofibrato foi eficiente em atenuar estas diferenças. Como conclusão, a dieta HL lidera para a obesidade, elevação da PA, hipertrofia cardíaca, alterações metabólicas e expressão proteica alterada do SRA em camundongos, sugerindo a participação do SRA nestas alterações. Fenofibrato é eficiente em diminuir a PA e controlar a expressão proteica do SRA, assim como no tratamento da resistência insulínica e do remodelamento cardíaco adverso, diminuindo a hipertrofia dos cardiomiócitos e melhorando a vascularização do miocárdio, desta maneira, diminuindo importantes fatores de risco para doenças ...

The aim was to study the action of fenofibrate, a peroxisome proliferator-activated receptor alpha agonist, in cardiac remodeling and protein expressions of RAS components in a model of obesity induced by diet. 3-mo-old C57B1/6 male were fed for 11 weeks with standard chow (SC group, 3.57 kcal/g of chow) or high-fat chow (HF group, 5.40 kcal/g of chow), then they were separated into four groups and studied for five weeks: SC; HF; SC-F (SC plus fenofibrate) and HF-F (HF plus fenofibrate). HF was heavier and had higher blood pressure (BP) than SC, but HF-F was lighter and had lower BP than HF. The insulin resistance seen in HF mice was corrected by fenofibrate in HF-F mice. Fenofibrate reduced total cholesterol, triglycerides and raised the HDL-c. HF had thicker and heavier left ventricle (LV) with bigger LV cardiomyocyte and smaller cardiomyocyte-to-capillaries ratio than SC, and fenofibrate was efficient in treating these alterations. Cardiac expressions of angiotensin II (ANG II) and ANG II receptor 1 were higher, and ANG II receptor 2 was lower in HF than in SC, and fenofibrate was efficient in attenuating these differences. In conclusion , HF diet leads to obesity, BP elevation, cardiac hypertrophy, metabolic changes and altered RAS protein expression in mice, suggesting that RAS is involved. Fenofibrate is efficient in decreasing BP and in controlling RAS protein expressions, and treats the insulin resistance and the adverse cardiac remodeling decreasing the cardiomyocyte hypertrophy and improving the myocardial vascularization, therefore, decreasing important cardiovascular risk factors

Role of Peroxisome Proliferator-Activated Receptor alpha in Diabetic Nephropathy

With a developing worldwide epidemic of diabetes mellitus, the renal complications associated with diabetes have become a serious health concern. Primary therapy for treating diabetic nephropathy is a multifactorial process. Peroxisome proliferator-activated receptor alpha (PPARalpha) agonists have been used primarily in clinical practice for the treatment of dyslipidemia and insulin resistance. Given that PPARalpha expression and regulation of metabolic pathways are involved in oxidative stress, inflammation, blood pressure regulation, and the renin-angiotensin aldosterone system, PPARalpha likely influences the development and pathogenesis of diabetic nephropathy via indirect effects on glucose and lipid homeostasis and also by direct action on the kidneys. These findings suggest that PPARalpha may become an important therapeutic target for treating diabetic renal complications.

Interaction among peroxisome proliferators-activated receptor alpha, cytochrome P450 oxysterol 7α-hydroxylase and estrogen receptor and its association with intrahepatic cholestasis in pregnant rats / 中华妇产科杂志

Objective To investigate the relationship between interaction of peroxisome proliferators-activated receptor alpha (PPARα), cytochrome P450 oxysterol 7α-hydroxylase (CYP7B1) and estrogen receptor (ER) and intrahepatic cholestasis in pregnant rats. Methods Eighty clean SD pregnant rats were selected and divided into four groups randomly with 20 in each. Since the 13th day of pregnancy,rats in the control group was injected subcutaneously with refined vegetable oil 2.0 ml · kg-1 · d -1 , those in the low-dose, moderate-dose and high-dose groups received 17-α-ethynylestradiol (EE) 1.0 mg · kg-1 · d-1,1.25 mg · kg-1 · d-1 and 1.5 mg · kg-1 · d-1, respectively. All rats were sacrificed at the 21at day of pregnancy and maternal hepatic tissues were collected. The serum levels of alanine aminotransferase(ALT), aspartate transaminase (AST), total bile acid (TBA) and bilirubin (BIL) were determined by enzyme linked immunosorbent assay (ELISA). The mRNA expressions of PPARα, CYP7B1, Erα and Erβ in maternal rat livers were examined by real-time PCR. Results (1) Biochemical indicators: the serum levels of ALT,AST, TBA and BIL were significantly lower in the control group than in the rest 3 groups,respectively [ control group: (41.1 ± 2.8 ) U/L, (44.4 ± 3.6) U/L, (26.4 ± 5.6 ) μmol/L and( 2.8 ± 0.2)U/L;low-dose group: (48.2 ±3.4) U/L,(47.9 ±3.7) U/L,(36.4 ±4.2) μmol/L and (4.2 ±0.2) U/L;moderate-dose group: (70.4 ± 5.3 ) U/L, (68.4 ± 5.6) U/L, (64.3 ± 3.8 ) μmol/L and ( 6.2 ± 1.2)U/L; high-dose group: (72.4 ±7.6) U/L, (70.2 ±3.8) U/L, (72.4 ±7.8) μmol/L and (8.2 ±2.2)U/L, P<0.05], and those in the moderate or high-dose groups were higher than in the low-dose group (P<0.05). (2) mRNA expression of Erα and Erβ: the mRNA expression of Erα in pregnant rat livers increased in a dose-dependent manner, which were all significantly higher than that in the control group,respectively ( low-dose group: 0.76 ± 0.02 ); moderate -dose group: ( 0.99 ± 0.04; high-dose group:1.21 ±0.01 ;control group:0.65 ±0.01, P <0.05), but no difference was found among the 4 groups in the mRNA expression of Erβ ( P > 0.05 ). (3) mRNA expression of CYP7B1 and PPARα: the mRNA expression of CYP7B1 in pregnant rat livers increased from the low-dose group to the high-dose group, and were all higher than that of the control group ( low-dose group: 0.93 ± 0.01; moderate-dose group: 0.99 ±0.06; high-dose group: 1.22 ± 0.04; control group: 0.75 ± 0.02, P < 0.05 ). However, the mRNA expression of PPARα decreased from the low-dose group to the high-dose group, and were all lower than that of the control group (low-dose group: 0.83 ± 0.05; moderate-dose group: 0.71 ± 0.02; high-dose group:0.64 ± 0.03; control group: 1.35 ± 0. 05; P < 0.05 ) . Conclusions The down regulated mRNA expression of PPARα, caused by higher dose of estrogen, may increase the expression of CYP7B1 due to the ineffectiveness of the inhibition of PPARα on CYP7B1, which may further stimulate the Erα activity and then induce intrahepatic cholestasis. Abnormal expression of PPARα, CYP7B1 and ER may play a role in the pathogenesis of estrogen-induced intrahepatic cholestasis.

Effect of peroxisome proliferator-activated receptor α agonist on mechanical ventilation-induced lung injury in rats / 中华麻醉学杂志

Objective To investigate the effect of peroxisome proliferator-activated receptor α agonist Wy14643 on mechanical ventilation-induced lung injury in rats.Methods Thirty-two healthy male SD weighing 250-300 g were randomly divided into 4 groups(n = 8 each): group Ⅰ control(group C);group Ⅱ mechanical ventilation(group V)and group Ⅲ,Ⅳ pretreated with different doses of Wy14643(group W1 ,W2).The animals were anesthetized with intraperitoneal 3% pentobarbital 30 mg/kg and tracheostomized.The femoral artery and external jugular vein were cannulated for blood sampling and drug administration.Group C received no mechanical ventilation.In group V,W1 and W2 the animals were mechanically ventilated for 2 h(VT 40 ml/kg,RR40 bpm,I:E=1:2,FiO2 21%).In group W1 and W2 Wy14643 1 and 3 mg/kg were administered iv at 1 h before mechanical ventilation.Arterial blood samples were collected at 1 and 2 h of mechanical ventilation for determination of PaO2/FiO2.Serum SOD activity and MDA concentration were measured at the end of 2 h mechanical ventilation.The animals were then killed and the lungs removed for microscopic examination,lung lavage and W/D lung weight ratio.The MIP-2 and TNF-α concentrations in BALF were measured.Results Two hour mechanical ventilation significantly decreased serum SOD activity and increased serum MDA concentration,W/D lung weight ratio and TNF-α and MIP-2 concentrations in BALF as compared with group C.Wy14643 pretreatment significantly attenuated these mechanical ventilation-induced changes in group W1 and W2 in a dose-dependent manner.Conclusion Wy14643 can attenuate mechanical ventilation induced lung injury in rats and it is related to the dose.

Fenofibrate Reduces Age-related Hypercholesterolemia in Normal Rats on a Standard Diet

Plasma cholesterol is increased in normal aging in both rodents and humans. This is associated with reduced elimination of cholesterol and decreased receptor-mediated clearance of plasma low-density lipoprotein (LDL) cholesterol. The aims of this study were: (1) to determine age-related changes in plasma lipid profiles, and (2) to determine the effect of fenofibrate, an activator of peroxisome proliferator activated receptor alpha (PPAR alpha), on plasma lipid profiles in normal rats on a standard diet. Male Sprague-Dawley (SD) rats (n=15) were fed standard chow and water from 10 to 25 weeks of age. During that period, we measured daily food intake, body weight, fasting and random blood glucose levels, plasma total cholesterol (TC), triglycerides (TG), and free fatty acid (FFA) levels. At 20 weeks of age, all rats were randomly divided into two groups: a fenofibrate group (in which rats were gavaged with 300 mg/kg/day of fenofibrate) and a control group (gavaged with water). Fenofibrate treatment lasted 5 weeks. There were no significant changes in daily food intake, blood glucose, and plasma TG level with age. Body weight, plasma TC, and FFA levels were significantly increased with age. Fenofibrate significantly decreased plasma concentrations of TC and FFA, which had been increased with age. However, fenofibrate did not influence the plasma concentration of TG, which had not increased with age. These results suggest that fenofibrate might have a novel role in preventing age-related hypercholesterolemia in SD rats on a normal diet.

Interação entre as vias de sinalização CD40/CD40L e os PPARs / Interections between CD40/CD40L and PPARs signaling pathways

O receptor CD40 e seu ligante CD40L possuem um papel importante na interface entre a resposta imune inata e a adaptativa. Disfunções desta via de sinalização são descritas em doenças de origem inflamatória e autoimunes. Em Lúpus eritematoso sistêmico (LES) foi descrito um aumento nos níveis séricos de CD40L solúvel, que participa na produção de autoanticorpos. Receptores ativados por proliferadores de peroxisomos (PPARs) são fatores de transcrição que inicialmente foram descritos como envolvidos apenas no metabolismo lipídico, mas que atualmente são também descritos como atuantes no controle da resposta imune. Com isso, nosso objetivo é determinar se a ativação dos PPARs modula o processo inflamatório através da interação com CD40/CD40L in vitro ou in vivo. Células de linhagem monocítica humana THP-1 foram tratadas por 24 horas com forbol-éster (PMA, 40 nM) e posteriormente estimuladas com CD40L recombinante (rhCD40L, 1 g/ml) por diferentes períodos. Transcritos de mRNA foram analisados por real time PCR e os resultados expressos como razão da expressão do gene housekeeping GAPDH. As células THP-1 apresentam um aumento na expressão de PPAR e após 16 e 2 horas de estímulo com rhCD40L, respectivamente. Estas células também foram estimuladas com LPS (10 g/ml) e LPS+rhCD40L para sabermos se a resposta obtida anteriormente era específica ao estímulo com rhCD40L. O resultado mostra que há uma diminuição na expressão de PPAR e após o estimulo com LPS ou LPS+rhCD40L, indicando que nessas condições a modulação da expressão de PPARs é especifica para a via de sinalização CD40/CD40L. Foi medida também a expressão de CD36, que é descrito na literatura como um indicador da atividade de PPARs. O resultado mostra que o estímulo com CD40L promove um aumento de CD36, o que indica indiretamente que o PPAR estava ativo neste modelo experimental. Para mostrar a interação direta destas duas vias de sinalização, silenciamos o gene de PPAR por siRNA e posteriormente anlisamos...

The membrane receptor CD40 and its ligand CD40L play an important role in the interface between innate and acquired immunity. Dysfunction of this signaling pathway was described in inflammatory and autoimmune diseases. In systemic lupus erythematosus (SLE), increased serum levels of soluble CD40L have been detected, where it plays a significant role in the generation of auto-antibodies. Peroxisome proliferator activator receptors (PPARs) are transcription factors originally described in lipid metabolism. More recently, they were also characterized as inflammatory modulators. Therefore, our objective was to determine whether the activation of PPARs may modulate the inflammatory process through interaction with the CD40/CD40L signaling pathway in vitro and in vivo. Macrophages derived from the human monocytic cell line THP-1 by 24h-treatment with PMA (40 nM) were stimulated with human recombinant CD40L (rhCD40L, 1 g/ml) for different periods. Messenger RNA (mRNA) transcripts for PPAR , and were determined by real time PCR and expressed as a ratio of the housekeeping gene GAPDH transcripts. THP-1 cells express a basal level of PPAR and gene transcription, which is increased 16 and 2 hours after exposure to rhCD40L, respectively. We also stimulated the THP-1 cells with LPS (10 g/ml) and LPS+rhCD40L to see if the increase of PPAR was a response specific to the rhCD40L stimuli. The data show that there is a decrease in PPAR and genes expression upon LPS or LPS+rhCD40L stimulation, indicating that in these times (2 and 16 hours) the response is specific for the CD40/CD40L signaling pathway. Increased expression of CD36 is known as an indicator of PPARs activity. We measured CD36 and saw an increase of this receptor after rhCD40L stimulus, indicating indirectly that PPARs were active in this experimental model. To prove the direct interaction between CD40/CD40L and PPAR , we silenced the PPAR gene by siRNA and analyzed the expression of CD80, which is known...

Safety and Efficacy of Peroxisome Proliferator-Activated Receptor-alpha Agonist for Treating Cardiovascular Disease

Peroxisome proliferator-activated receptor (PPAR)-alpha belongs to the nuclear family of ligand-activated transcriptional factors. The main role of PPAR-alpha is to activate the expression of the genes that are involved in fatty acid oxidation to achieve energy homeostasis. Fibrates are a known class of PPAR-alpha agonists, and they been used clinically for their effects of lowering triglycerides and elevating high-density lipoprotein-cholesterol (HDL-C). Further, recent experimental studies have demonstrated the anti-inflammatory and anti-atherosclerotic actions of PPAR-alpha agonists directly on the vascular wall. PPAR agonists are currently emerging as a promising therapeutic option to control systemic and vascular atherogenic factors. Regardless of their strong anti-atherosclerotic properties, large clinical studies have demonstrated inconsistent results for the cardioprotective effect of PPAR-alpha agonists; moreover, it has been observed that they did not decrease the total mortality, which stands in contrast to the statin trials. This review summarizes the current knowledge regarding the PPAR biology and the mechanisms of the effects of PPAR-alpha on lipid metabolism, the vessel wall and the cardiac metabolism. We also describe the results and lessons learned from the important clinical trials of PPAR-alpha agonists and we discuss these drugs' efficacy and safety.

Phenotype of peroxisome proliferator-activated receptor-alpha(PPARalpha)deficient mice on mixed background fed high fat diet

Considerable controversy exists in determining the role of peroxisome proliferator-activated receptor-alpha(PPARalpha) on obesity. Previous reports demonstrated that PPARalpha is a critical modulator of lipid homeostasis, but the overt, obese phenotypic characterization in the strain of PPAR deficient (PPARalpha-/-) mice is influenced by other factors, including diet and genetics. Therefore, it is necessary to establish the phenotypic characterization of PPARalpha-/- mice prior to the obesity-related study. In this study, we observed phenotype of PPARalpha-/- mice on mixed genetic background (C57BL/6Nx129/Sv) fed a high fat diet for 16 weeks. PPARalpha-/- mice, regardless of sex, raised body growth rate significantly comparing with wild type and showed male-specific fatty change in the liver. They were shown to lack hepatic induction of PPARalpha target genes encoding enzymes for fatty acid beta-oxidation.

Fenofibrate regulates obesity and lipid metabolism with sexual dimorphism

To determine whether the PPARalpha agonist fenofibrate regulates obesity and lipid metabolism with sexual dimorphism, we examined the effects of fenofibrate on body weight, white adipose tissue (WAT) mass, circulating lipids, and the expression of PPARalpha target genes in both sexes of high fat diet-fed C57BL/6J mice. Both sexes of mice fed a high-fat diet for 14 weeks exhibited increases in body weight, visceral WAT mass, as well as serum triglycerides and cholesterol, although these effects were more pronounced among males. Feeding a high fat diet supplemented with fenofibrate (0.05% w/w) reduced all of these effects significantly in males except serum cholesterol level. Females on a fenofibrate-enriched high fat diet had reduced serum triglyceride levels, albeit to a smaller extent compared to males, but did not exhibit decreases in body weight, WAT mass, and serum cholesterol. Fenofibrate treatment resulted in hepatic induction of PPAR alpha target genes encoding enzymes for fatty acid beta-oxidation, the magnitudes of which were much higher in males compared to females, as evidenced by results for acyl-CoA oxidase, a first enzyme of the beta-oxidation system. These results suggest that observed sexually dimorphic effects on body weight, WAT mass and serum lipids by fenofibrate may involve sexually related elements in the differential activation of PPARalpha.