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Regulación de la autofagia del cardiomiocito por ligandos farmacológicos del receptor activado por proliferadores peroxisomales gama (PPARγ)Valenzuela Bassi, Rodrigo Andrés January 2011 (has links)
Doctor en Farmacología / Diversos estudios clínicos han revelado que las tiazolidinedionas, fármacos
para el tratamiento de la diabetes de tipo 2 y resistencia a insulina, podrían reducir
la morbimortalidad cardiovascular. Su mecanismo de acción es a través de la
activación de los Receptores Activados por Proliferadores Peroxisomales (PPARs),
los cuales son factores transcripcionales activados por ligandos. En el sistema
cardiovascular, los PPARs se expresan de forma variable y juegan un importante
papel en la regulación del metabolismo energético y en la respuesta inflamatoria.
Durante diversos estados patológicos como por ejemplo en el infarto al miocardio,
el tratamiento con tiazolidinedionas ha mostrado efectos cardioprotectores ya que
reducen la hipertrofia y el área infartada y atenúan la respuesta inflamatoria
cardiaca. Estos antecedentes sugieren un importante papel de PPARγ durante el
remodelado cardiaco, proceso fisiopatológico que consiste en un cambio estructural
y funcional del tejido, caracterizado por fibrosis, hipertrofia y pérdida progresiva de
los cardiomiocitos.
Se ha sugerido que la apoptosis es el principal mecanismo de muerte celular
en el corazón pero últimamente se ha avanzado en los estudios de la participación
de la autofagia o “muerte programada de tipo II”. Sin embargo, la autofagia se
describió inicialmente como un proceso fisiológico clave para la sobrevida celular
durante la privación de aminoácidos, diferenciación celular y desarrollo. Consiste
en un proceso dinámico y programado que procede con el secuestro de proteínas
citoplasmáticas y organelos enteros dentro de vacuolas de doble membrana, que
posteriormente se fusionan con los lisosomas formando los autolisosomas. Todos
estos elementos capturados en las vacuolas son degradados por proteasas
lisosomales y removidos de la célula por exocitosis. Evidencias recientes han mostrado que los agonistas de PPARγ podrían inducir la autofagia en algunas
líneas celulares. Sin embargo, aún no queda claro si la autofagia es realmente un
proceso de muerte o un mecanismo de sobrevida celular. Dado que prácticamente
se desconoce si la activación de PPARγ regula la autofagia cardiaca, en esta tesis
se postuló como hipótesis que “El agonista farmacológico de PPARγ rosiglitazona
induce la autofagia del cardiomiocito, protegiéndolo de la muerte”.
Los objetivos específicos propuestos fueron:
• Estudiar in vitro el efecto de agonistas farmacológicos de PPARα y/o PPARγ en la
viabilidad del cardiomiocito de rata.
• Determinar si rosiglitazona induce autofagia en el cardiomiocito y si ésta se relaciona
con sobrevida celular.
• Investigar si la estimulación con rosiglitazona afecta la viabilidad de cardiomiocitos
expuestos a estrés nutricional, estrés hiperosmótico o a isquemia/reperfusión
simulada.
El modelo experimental utilizado fue cultivo primario de cardiomiocitos de ratas
neonatas tratados con rosigllitazona en un rango creciente de concentraciones y de
tiempo. La autofagia se evaluó mediante procesamiento de la proteína LC3 endógena,
cambio en la distribución y degradación de la proteína GFP-LC3 en cardiomiocitos
transducidos con el adenovirus GFP-LC3.
Los resultados mostraron que PPARγ está presente en cardiomiocitos de ratas
y que es transcripcionalmente activo, lo cual se demostró mediante un plasmidio
reportero que contiene el elemento de respuesta para este factor transcripcional.
Además, rosiglitazona estimuló temprana y progresivamente la autofagia en los cultivos
primarios de cardiomiocitos, determinada por el procesamiento de la proteína
endógena LC3-I, efecto similar al observado en repuesta al tratamiento con rapamicina.
Rosiglitazona también incrementó la distribución punteada de LC3-GFP, sin embargo no disminuyó la fluorescencia de la proteína LC3-GFP en los cardiomiocitos
transducidos con el adenovirus LC3-GFP. Por otra parte, rosiglitazona no modificó de
forma significativa los niveles intracelulares de ATP y ni afectó la viabilidad basal del
cardiomiocito. El tratamiento con gemfibrozilo, tampoco modificó su viabilidad.
Para determinar si la inducción de autofagia tiene un efecto en la viabilidad
del cardiomiocito, los cultivos celulares se expusieron a estrés mecánico por
hiperosmolaridad y se midió la viabilidad. El estrés hiperosmótico indujo de manera
rápida y potente la muerte de las células cardiacas. Sin embargo, rosiglitazona y
gemfibrozilo no previnieron este efecto. La muerte de las células cardiacas inducida
por el estrés hiperosmótico es mediante apoptosis, lo que se demostró la
evaluación por citometría de flujo de la subpoblación G1 en células permeabilizadas
y tratadas con yoduro de propidio y determinación de potencial mitocondrial.
Rosiglitazona y gemfibrozilo no previnieron la apoptosis del cardiomiocito inducida
por estrés hiperosmótico. Rosiglitazona tampoco bloqueó la muerte celular
inducida por isquemia y reperfusión simulada.
Finalmente, los resultados obtenidos con el desarrollo de esta tesis permiten
concluir que rosiglitazona induce la autofagia del cardiomiocito pero que ésta es
insuficiente para modificar la viabilidad celular / Clinical studies showed that thiazolidinediones, drugs used for type 2 diabetes
and insulin resistance treatment, can reduce cardiovascular morbid and mortality.
These compounds are highly specific ligands of peroxisome proliferator-activator
receptor gamma (PPARγ), a nuclear hormone receptor superfamily member. PPARs
are variably expressed in the cardiovascular system and play an important role in both
energetic metabolism regulation and inflammation response. In myocardial infarct,
treatment with thiazolidinediones has cardioprotective effects reducing cardiac
hypertrophy, infarcted area and inflammatory response. These data suggest an
important role of PPARγ during cardiac remodeling. Remodeling is a
physiopathological alteration in heart structure and function characterized by
cardiomyocytes fibrosis, hypertrophy and death.
Apoptosis has been described as the main cardiac cell death mechanism.
However, recent studies have also described the participation of autophagy, also known
as type II programmed cell death. Autophagy was first described as an adaptative
physiological process during amino acids starvation. It has also been described its
participation in cellular differentiation and development. Autophagy consists in the
sequestration of cytoplasm portions and organelles within double membrane vesicles,
named autophagosomes. These vesicles were subsequently fused with lysosomes
forming the autofagosomes. All elements captured in these vesicles are degraded by
lysosomal proteases and removed by exocytosis. Recent evidence has shown that
PPARγ agonists could induce autophagy in some cells lines. However, is not clear
whether autophagy is a mechanism for cell survival or death. Based on these
antecedents we postulated the following hypothesis: “The pharmacological PPARγ
agonist, rosiglitazone, induces cardiomyocyte autophagy protecting them from cell
death”. The specific aims were:
• To study in vitro the effects of PPARα and PPARγ pharmacological agonists on
neonatal rat cardiomyocytes.
• To determine whether rosiglitazone induces autophagy in cardiomyocyte and
whether this process is related with cell viability.
• To investigate if the stimulation with rosiglitazone affects cardiomyocyte viability
when exposed to nutritional stress, hyperosmotic stress and simulated
ischemia/reperfusion.
The experimental models were primary cultures of neonatal rat cardiomyocytes
treated with rosiglitazone at different concentrations and times. Autophagy was
evaluated by endogenous LC3-I processing, and by change in adenoviral expressing
GFP-LC3 distribution and degradation.
Results showed that PPARγ is expressed and is transcriptionally active in
neonatal rat cardiomyocytes as determined by western blot and activity of PPAR
reporter plasmid. Furthermore, rosiglitazone stimulated early and progressively
cardiac autophagy as determined by endogenous LC3-I processing. This effect was
similar to that induced by rapamycin. Rosiglitazone also increased the GFP-LC3
punctuated pattern, but without decreasing GFP-LC3 fluorescence. On the other
hand, rosiglitazone neither affects ATP levels nor viability of cardiomyocytes.
Gemfibrozil treatment, also did not affect cardiomyocyte viability.
To determine whether autophagy affects cardiomyocyte viability, cultured cells
were exposed to hyperosmotic stress in the presence or absence of rosiglitazone or
gemfobrozil, and viability was measured. Hyperosmotic stress induced a rapid
decrease in cardiomyocyte viability. Cardiomyocyte death was also achieved by simulated ischemia/reperfusiom. Neither rosiglitazone nor gemfibrozil prevented
cardiomyocyte death induced by both procedures. Hyperosmotic stress-induced cell
death was characterized as apoptosis, as determined by mitochondrial potential decay
and DNA fragmentation visualized by sub G1 population in propidium iodide-treated
cells followed flow cytometry. Both rosiglitazone and gemfibrozil did not prevent the
hyperosmotic stress-induced apoptosis.
Finally, these results allow us to conclude that rosiglitazone induces
cardiomyocyte autophagy but this process does not affect cardiomyocyte viability
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Determinação de citocinas da via TH17 e da atividade imunomoduladora de novos derivados tiazolidinicos em PBMCs de crianças asmáticasANTUNES, Adriana Azoubel 28 May 2013 (has links)
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Previous issue date: 2013-05-28 / CNPq / A asma é uma doença heterogênea com quadros clínicos e mecanismos patogênicos
distintos. Sua fisiopatologia envolvendo a predominância de fenótipo Th2 não tem sido
suficiente para explicar a diversidade fenotípica observada nestes pacientes. Com a
descoberta das células Th17, produtoras de IL-17A, IL-17F e IL-22, várias evidências
têm sido descritas implicando sua participação na patogênese da asma. Com isso, novas
perspectivas terapêuticas a uma série de doenças vêm sendo consideradas. Os derivados
tiazolidínicos são drogas agonistas dos receptores ativados por proliferadores de
peroxissoma gama (PPARγ) e atuam em várias doenças auto-imunes e inflamatórias.
Em nosso estudo revisamos o papel das citocinas da via Th17 na asma brônquica. Esta
tese tem ainda dois artigos originais: No primeiro avaliamos a produção destas citocinas
em uma população de crianças com asma persistente moderada e grave, na tentativa de
correlacionar estes níveis com a gravidade da doença, e ainda comparar com controles
não asmáticos. Avaliamos ainda, in vitro, se as citocinas pró-inflamatórias presentes em
meio de cultura de células mononucleares de sangue periférico (PBMCs) seriam
inibidas pela presença de um composto tiazolidínico, o GQ-147, o que motivou o
segundo artigo original. Os pacientes foram avaliados e classificados clinicamente
quanto à gravidade da asma e submetidos a exames complementares. As citocinas foram
dosadas no soro e nos sobrenadantes das PBMCs. Observamos níveis séricos de IL-17 e
IL-22 abaixo do limite de detecção da técnica. Nas culturas celulares observamos uma
elevação da IL-17 quando comparamos o grupo de asmáticos persistentes graves com os
moderados, embora esta diferença não tenha sido estatisticamente significante. Com o
GQ-147, verificamos uma diminuição das IL-17, IFNγ e IL-22. Além disto,
demonstramos por reação em cadeia da polimerase em tempo real (Real-time PCR) que
o GQ-147 teria uma ação imunomoduladora nos PPARγ mais eficiente que a
rosiglitazona, tiazolidínico comercialmente disponível. Frente à complexidade que é
tratar uma doença de fenótipos inflamatórios tão distintos, outros estudos com um maior
número de pacientes, são necessários para a confirmação deste possível predomínio das
citocinas Th17 nos casos de asma grave, bem como a ação imunomoduladora do
composto estudado, para posterior avaliação em ensaios clínicos.
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The use of CHS-131, a selective PPAR-gamma modulator to treat NAFLD/NASHJoshi, Aditya 05 June 2020 (has links)
BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) and its progression to non-alcoholic steatohepatitis (NASH) is a spectrum of diseases that is rising in prevalence and is strongly associated with obesity, diabetes, and insulin resistance. There has been much research into potential therapeutics, as the current recommended treatment, thiazolidinediones (TZDs) present a host of negative side effects such as fluid retention and weight gain. CHS-131 is a selective PPAR-γ modulator with antidiabetic effects and less side effects compared to TZDs. The aim of this study was to investigate the effects of CHS-131 on metabolic parameters and liver pathology in a diet-induced obese (DIO) and biopsy-confirmed mouse model of non-alcoholic steatohepatitis.
METHODS: Male C57BL/6JRj mice were fed an AMLN diet (40% fat with trans-fat, 20% fructose and 2% cholesterol) for 33 weeks prior to a liver biopsy procedure. Animals that were biopsy-confirmed to have steatosis and fibrosis were stratified into 3 treatment groups: 1) Low dose CHS-131 (10mg/kg), 2) High dose CHS-131 (30mg/kg), 3) Vehicle. Metabolic parameters, liver pathology including NAFLD activity score, metabolomics/lipidomics, markers of liver function and liver, subcutaneous and visceral adipose tissue gene expression was assessed.
RESULTS: CHS-131 did not affect body weight, fat, lean or water mass, or food intake in DIO-NASH mice with fibrosis. CHS-131 improved fasting insulin levels and insulin sensitivity as assessed by intraperitoneal insulin tolerance test. CHS-131 improved total cholesterol, ALT, AST and increased adiponectin levels in plasma. CHS-131 improved NAS in liver histology and tended to reduce markers of hepatic fibrosis. Diet induced NASH mice treated with CHS-131 demonstrated a hepatic shift to diacyl- and triacyl-glycerol’s with shorter chains, increased expression of genes stimulating fatty acid oxidation and browning and decreased expression of genes promoting fatty acid synthesis, triglyceride synthesis and inflammation in adipose tissue.
CONCLUSION: CHS-131 improves liver histology in a diet-induced obese and biopsy confirmed mouse model of NASH by affecting the hepatic lipidome, reducing insulin resistance and altering lipid metabolism and inflammation in adipose tissue. / 2022-06-04T00:00:00Z
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Étude des fibrates en tant qu'agents stimulateurs de la synthèse des cétones, des substrats énergétiques pour le cerveau vieillissantTremblay-Mercier, Jennifer January 2008 (has links)
Les fibrates sont utilisés cliniquement pour traiter l'hypertriglycéridémie. Leurs actions sont médiées par le peroxisome proliferator activated receptor [alpha] (PPAR [alpha]), un récepteur nucléaire hautement exprimé dans le foie, qui régule l'expression des gènes impliqués dans la lipolyse, la [bêta]-oxydation et la synthèse des cétones.Les cétones, produites à partir de la dégradation des acides gras, sont des substrats énergétiques alternatifs pour le cerveau lorsque les concentrations de glucose diminuent. Lors du vieillissement, dans des cas de déclin cognitif ou de maladie d'Alzheimer, la captation du glucose par le cerveau diminue ce qui perturbe son homéostasie énergétique.Les cétones, en concentration plasmatique suffisante, pourraient pallier efficacement au manque énergétique cérébral. Le potentiel des fibrates à stimuler la production des cétones n'a jamais été étudié chez l'homme. Objectif. Évaluer la capacité des fibrates, des agents activateurs du PPAR[alpha], à stimuler la production des cétones chez les humains. Méthodes : Trois études ont été réalisées. La première étude (a) comparait les concentrations plasmatiques de cétones d'un groupe traité avec les fibrates avec un groupe témoin, non traité aux fibrates.Les deux autres études cliniques comparaient les concentrations de cétones à jeun et lors d'une journée métabolique de 6 heures avant et après (b) un traitement de 12 semaines avec le bezafibrate sur 10 personnes légèrement hypertriglycéridémiques et (c) l'arrêt d'un traitement au fénofibrate pour une période de 6 semaines, sur 10 personnes déjà sous médication au fénofibrate. Résultats : Dans les trois études, les concentrations plasmatiques de cétones à jeun n'ont pas été augmentées significativement par les fibrates. Dans les deux études cliniques, comme attendu, les fibrates ont diminué significativement les triglycérides. Par contre, les fibrates n'ont pas augmenté les concentrations de cétones à jeun ni aux différents temps de la journée. Cependant, après 12 semaines de traitement avec le bezafibrate, la réponse post prandiale des cétones, obtenue par l'aire sous la courbe des données normalisées par rapport aux concentrations à jeun, a été augmentée de 85%. Conclusion : La cétogenèse n'est pas stimulée par la prise d'un fibrate quand le contexte métabolique n'est pas favorable. Un besoin énergétique est nécessaire pour initier la cétogenèse mais la présence d'un fibrate aurait un certain potentiel pour favoriser cette voie métabolique. Perspectives : Le recrutement se poursuit pour mieux définir l'effet des fibrates sur les cétones et d'autres stratégies devront être mises de l'avant, comme la combinaison d'un fibrate avec un apport en substrats facilement oxydables, pour induire un état de cétose chronique afin de favoriser la captation des cétones par le cerveau.
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NUTRIENT MEDIATED PROTECTION AGAINST ENDOTHELIAL CELL DYSFUNCTIONReiterer, Gudrun 01 January 2004 (has links)
Atherosclerosis is thought to be initiated by endothelial cell dysfunction. Research described in this dissertation is focused on interactions of nutrients, cytokines and pharmaceutical compounds in the intracellular signaling pathways leading to endothelial cell activation. The flavonoid quercetin could significantly downregulate the inflammatory pathways induced by linoleic acid as determined by DNA binding assays of the proinflammatory transcription factors nuclear factor-kappaB and activator protein-1 as well as by gene expression studies of interleukin-6 and vascular adhesion molecule-1. Interestingly, quercetin and vitamin E also prevented the linoleic acid-induced activation of PPAR DNA binding - suggesting a role of oxidation in the fatty acid-mediated induction of PPAR. In addition, we studied an interaction of zinc with the antiinflammatory transcription factors, peroxisome proliferator activated receptors (PPARs) alpha and gamma. Our data suggest that PPAR alpha and gamma and their synthetic agonists require zinc for their antiinflammatory properties in endothelial cells. We could confirm the importance of zinc in PPAR gamma signaling in vivo by a decreased PPAR DNA binding activity in livers of zinc deficient mice. Furthermore, zinc had dramatic lipid lowering effects in LDL-receptor deficient mice on a diet rich in corn oil. Triglycerides, phospholipids and cholesterol levels were significantly elevated in mice receiving a zinc deficient diet when compared to control and where decreased in zinc supplemented animals. Zinc deficiency also increased oxidative stress as determined by quantitation of plasma isoprostanes and mRNA expression of glutathione reductase. In conclusion, our data show novel interactions of proinflammatory nutrients, such as linoleic acid, with antioxidant and anti-inflammatory nutrients, such as quercetin and zinc.
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Interação entre as vias de sinalização CD40/CD40L e os PPARs / Interections between CD40/CD40L and PPARs signaling pathwaysOxer, Daniella Stefani 15 December 2008 (has links)
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 a expressão de CD80, cuja expressão encontra-se aumentada logo após a ativação do CD40 de acordo com a literatura. O resultado mostra que, com o silenciamento de PPAR , há um aumento de CD80 logo após a ativação do CD40, evidenciando assim a interação entre essas duas vias de sinalização. A fim de verificar se os achados encontrados in vitro poderiam ser observados in vivo, foi isolada a fração mononuclear de sangue periférico de pacientes com LES com a doença em atividade (n=17), a doença inativa (n=21) ou doadores saudáveis (n=12) e foi medida a expressão de PPAR e por real time PCR. PPAR apresenta um aumento em pacientes com a doença ativa ou inativa em comparação aos doadores saudáveis. Já a expressão de PPAR apresenta aumento apenas em lúpicos em atividade quando comparados com lúpicos inativos ou doadores saudáveis. Quando considerado nesta análise o efeito do tratamento dos pacientes com corticosteróides nos níveis de PPAR, obsevou-se que a expressão de PPAR apresenta o mesmo padrão anterior. Estes resultados sugerem a hipótese de que PPAR seja um possível marcador de atividade de LES. Para confirmar esta especificidade, foram adicionadas à analise células mononucleares retiradas de pacientes com tuberculose e com infecções agudas. Os dados mostram que os níveis elevados de PPAR se mantém apenas em pacientes com lúpus ativo, o que confirma nossa hipótese. Nossos achados sugerem que PPAR e são regulados especificamente em reposta a ativação da via do CD40/CD40L, em monócitos em cultura e em células obtidas de pacientes com LES. Podemos também sugerir que PPAR possa ser um marcador para a atividade de LES. Estes resultados podem representar um novo mecanismo de controle da via de sinalização do CD40/CD40L, participando no controle da resposta inflamatória em cultura e em células de pacientes lúpicos / 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 to increase after CD40 activation. The results show an increase in CD40L-stimulated CD80 expression upon silencing of PPAR , showing that there is an interaction between these signaling pathways. To confirm whether these findings also occur in vivo, mononuclear cells were isolated from whole blood samples from SLE patients with active (n=17) and inactive disease (n=21), and healthy donors (n=12). The mRNA transcripts for PPARs were detected by real time PCR. In both active and inactive SLE patients, monocytes show an increase in PPAR mRNA expression, as compared to healthy donors. PPAR mRNA is increased only in active patients when compared to healthy donors and inactive lupus patients. Further in this analysis, when we separated the patients with and without the administration of corticosteroids, PPAR displayed the same pattern as above. These results suggested that PPAR may be a marker for lupus activity. To validate this hypothesis, we compared the results obtained from patients with tuberculosis and acute infections. Results showed that only active-lupus patients have an increase in PPAR , confirming the specificity of this phenomenon and hence our hypothesis Our findings suggest that PPAR and are up-regulated specifically in response to CD40/CD40L activation, in both cultured macrophages and in monocytes obtained from SLE patients. We could also suggest that PPAR may be marker for lupus activity. Our results may represent a new control mechanism of the CD40/CD40L signaling pathway and seem to be implicated in the control of the inflammatory response in both human macrophages in vitro and SLE patients
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Exercício aeróbio crônico reduz o acúmulo de gordura hepático, mas promove inflamação no fígado de camundongos PPAR-alpha knockout, via inibição do PPAR-gama. / Aerobic Exercise decreases NAFLD, but promotes liver inflammation in PPAR-alpha knockout mice via PPAR-gamma inhibition.Batatinha, Helena Angelica Pereira 24 September 2015 (has links)
A NAFLD é uma das principais patologias de fígado. Estudos reportam o exercício físico como um dos principais alvos terapêuticos para esta doença. Verificamos se o treinamento melhora a resistência à insulina, inflamação e esteatose hepática causados pela dieta hiperlipídica (HF) e se o PPAR-alpha está envolvido neste processo. Animais selvagens C57BL6 (WT) e knockout para PPARα (KO) foram alimentados com dieta padrão ou HF durante 12 semanas e treinados por 8 semana. Metade dos animais KO treinados receberam rosiglitazona. A dieta HF aumentou TAG hepático, e resistência periférica à insulina levando a NALFD. O treinamento foi eficiente em reduzir esses parâmetros em ambos genótipos. O desenvolvimento da NAFLD não foi associado à inflamação hepática, entretanto animais KO treinados apresentaram uma resposta inflamatória exacerbada, causada pela redução de PPARγ. Quando eles receberam rosi apresentaram melhora no quadro inflamatório hepático e na resistência à insulina. O exercício diminuiu os danos causados pela dieta HF independente do PPARα; a ausência do PPARα junto com exercício leva a queda na expressão de PPARγ, e a uma resposta inflamatória exacerbada, que é revertida pela administração da rosiglitazona. / NAFLD is one of the main liver diseases. Studies have shown the beneficial effects of exercise on reverse NAFLD. We verify whether exercise improve insulin resistance, liver inflammation and steatohepatitis caused by a high fat diet (HF) and whether PPARα is involved in these actions. C57BL6 wild type (WT) and PPAR-α knockout (KO) mice were fed with a standard (SD) or HF during 12 weeks and trained on a treadmill during 8 weeks, half of KO trained animals received 15mg/kg/day of rosiglitazone. HF diet increased TAG in the liver and peripheral insulin resistance leading to NAFLD. Exercise reduced all this parameters in both animals genotype. NAFLD was not associated with inflammation, however KO mice when trained presented an inflammatory response that was caused by a decrease on PPARγ. When these mice were treated with rosiglitazone, they presented decrease on inflammatory cytokines as well as improvement on insulin sensitivity. Exercise improved the damage caused by a HF independently of PPARα and the absence of PPARα together with exercise leads to decrease on PPARγ expression and an inflammatory response, which was attenuated by rosiglitazone administration.
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Role of PPAR[gamma] and retinol binding protein 7 in the vascular endotheliumWoll, Addison Wayne 15 December 2017 (has links)
Peroxisome Proliferator-Activated Receptors (PPARs) are a family of conserved ligand activated nuclear receptor transcription factors heterogeneously expressed in mammalian tissues. PPARγ is recognized as a master regulator of adipogenesis, fatty acid metabolism, and glucose homeostasis, but genetic evidence also supports the concept that PPARγ regulates the cardiovascular system, particularly vascular function and blood pressure. There is now compelling evidence that the beneficial blood pressure lowering effects of PPARγ activation are due to its activity in vascular smooth muscle and endothelium, through its modulation of nitric oxide-dependent vasomotor function. Endothelial PPARγ regulates the production and bioavailability of nitric oxide, while PPARγ in the smooth muscle regulates the vasomotor response to nitric oxide. We recently identified retinol binding protein 7 (RBP7) as a PPARγ target gene that is specifically and selectively expressed in the endothelium. We will discuss the evidence that RBP7 is required to mediate the antioxidant effects of PPARγand mediate PPARγ target gene selectivity in the endothelium, as well as the work so far in determining the mechanism of RBP7:PPARγ interaction. (56)
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Suppression of Oxidative Stress in the Rostral Ventrolateral Medulla Contributes to Antihypertensive Effect of the Peroxisome Proliferator Activated Receptor Activator RosiglitazoneWu, Chiung-ai 30 July 2008 (has links)
Peroxisome proliferator activated receptors (PPAR) are members of the nuclear receptor family that act as transcription factors to regulate target gene expression. In addition to their well-known effects in regulation of glucose homeostasis and lipid metabolism, PPAR activators have recently been shown to exert antihypertensive effects, although the underlying mechanism is not clear. Our laboratory has previously demonstrated that oxidative stress of an augmented tissue level of superoxide anion (£R2¡E−) in the rostral ventrolateral medulla (RVLM), where promotor neurons for generation of sympathetic vasomotor outflow reside, contributes to neural mechanism of hypertension. I therefore propose to test in my thesis the hypothesis that protection against oxidative stress after activation of the PPARs in the RVLM may contribute to the antihypertensive effect of these transcription factors.
Experiments were performed in the spontaneously hypertensive rats (SHR) or normotensive Wistar-Kyoto (WKY) rats under anesthesia or conscious condition. Compared to WKY rats, microinjection bilaterally into the RVLM of a synthetic activator of PPAR£^, rosiglitazone (1 nmol), evoked significantly greater decreased in mean systemic arterial pressure (MSAP) and heart rate (HR) in SHR. These cardiovascular suppressive
effects of rosiglitazone were accompanied by greater decrease in tissue level of O2
- and upregulation of the antioxidant uncoupling proteins (UCPs) in the RVLM of SHR. Rosiglitazone also caused a significant greater increase in PPAR£^ expression in the nuclear extracts from RVLM of SHR than WKY rats. All these cellular events induced by rosiglitazone were antagonized by co-administration into the RVLM of the PPAR£^ inhibitor, GW9662 (5 nmol). This PPAR£^ inhibitor also significantly reversed the cardiovascular depressive effects of rosiglitazone. Together these results suggest that PPAR£^ in the RVLM may participate in central cardiovascular regulation by promoting hypotension and bradycardia via amelioration of O2- production and upregulation of antioxidant UCPs. Moreover, a downregulation of the PPAR£^ in the RVLM may contribute to neural mechanism of hypertension.
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Transcriptional regulation of T helper cell differentiation in autoimmunityGocke, Anne Elizabeth January 2006 (has links)
Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2006. / Vita. Bibliography: pp. 152-183.
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