Reproduction de : Thèse de doctorat : Immunologie : Lille 2 : 2008. / Résumé en français et en anglais. Titre provenant de l'écran-titre. Bibliogr. f. 60-79.

Cadmium (Cd) is present in food at low levels, particularly in crops and is also present in groundwater. Cd can also be obtained from tobacco smoking and occupational exposure. Cd is not effectively excreted from the body. The primary organ that accumulates Cd is liver. Liver is the main organ involved in metabolizing exogenous chemicals. While metabolism of chemicals causes detoxification, it can also result in liver oxidative damage. CYP2A6 (CYP2A5 in mice) is mainly expressed in the liver. CYP2A6 expression is increased in patients with alcoholic or non-alcoholic fatty liver. Alcohol feeding induced CYP2A5 in mice and alcohol-induced fatty liver disease was enhanced in CYP2A5 knockout (CYP2A5-/-) mice, suggesting a protective effect of CYP2A5 on alcoholic fatty liver disease. PPAR-alpha, a transcription factor, is a major regulator of lipid metabolism in the liver.  CYP2A5 and PPAR-alpha are suggested to work together in regulation of lipid metabolism and in protection against alcoholic fatty liver. It is also suggested that CYP2A5 along with PPAR-alpha protects against high fat diet induced metabolic syndrome. Cadmium can also induce CYP2a5 in mice. Recently it was discovered that there is a positive relation between soil heavy metals and fatty liver disease. Exposure to Cadmium leads to lipid accumulation in the liver, which can eventually lead to the development of Non-Alcoholic Fatty Liver Disease (NAFLD). In this study, the effects of CYP2A5 and PPAR-alpha on the acute cadmium-induced liver injury were tested using CYP2A5-/- mice and PPAR-alpha knockout (PPARα -/-) mice and CYP2A5 and PPAR-alpha wild-type mice. Cadmium chloride (CdCl2) was administered intraperitoneally at 5 mg/kg body weight. A control group of mice were injected saline for comparison. The mice were sacrificed after 24 hours of injection. Blood was collected to test for markers indicative of liver disease such as ALT and AST levels, triglyceride levels, and blood glucose levels. The liver was collected to examine the liver damage by biochemical assays and pathological evaluation. Both CYP2A5-/- and PPARα -/- mice exhibited less severe liver injury compared to their wild-type counterparts. These results suggest that despite the beneficial roles of both CYP2A5 and PPAR-alpha towards alcohol-induced liver injury and metabolic syndrome, they are not protective against Cd-induced liver injury.

No description available.

No description available.

Le carcinome rénal à cellules claires (cRCC) est le principal type histologique de carcinome rénal et l'une des tumeurs les plus résistantes à la chimio et à la radiothérapie. L'absence de biomarqueurs pour la détection précoce et pour le suivi des patients est responsable d'un mauvais pronostic. Il est nécessaire d'identifier de nouveaux biomarqueurs et des cibles thérapeutiques pour améliorer la prise en charge des patients. Les microARNs, des petits ARN non codants de 22 nucléotides, qui ont été précédemment montrés comme favorisant l'initiation et la progression tumoral, semblent être de bons candidats. Nous avons focalisé notre étude sur (i) miR-21 qui est le principal oncomiR surexprimé dans le cRCC et (ii) le récepteur nucléaire PPARα (Peroxisome Proliferator Activated Receptor), l'une des cibles de miR-21.D'une part, sur une cohorte de 99 échantillons de cRCC primaires, nous avons montré que l'expression de miR-21 était plus élevée dans les tissus cancéreux que dans les tissus non tumoraux adjacents. In vitro, miR-21 est également surexprimé dans les lignées cellulaires de carcinomes rénaux comparées à la lignée cellulaire épithéliale HK-2 provenant de tubes proximaux humains. De plus, nous avons également montré que la surexpression de miR-21 augmente les propriétés de migration et d'invasion des cellules cancéreuses rénales ainsi que les voies de signalisation prolifératives et anti-apoptotiques, alors que des résultats opposés ont été observés en utilisant une stratégie d'inhibition anti-miR-21. Enfin, nous avons évalué le rôle du miR-21 dans la chimiorésistance du cRCC et montré, en outre, que l'inhibition de miR-21 augmentait significativement la chimiosensibilité au paclitaxel, au 5-fluorouracile, à l'oxaliplatine et au dovitinib, diminuait l'expression des transporteurs à efflux MRP1-6/ABCC1-6 et augmentait l'expression des transporteurs à influx SLC22A1/OCT1, SLC22A2/OCT2 et SLC31A1/CTR1. Ces résultats ont permis la publication d'un article dans Tumor Biology se trouvant en annexe.D'autre part, dans les tissus de patients atteints de cRCC, nous avons montré pour la première fois que la surexpression de miR-21 est en corrélation avec une perte d'expression de PPARα. In vitro, nous avons montré que miR-21 cible le 3'-UTR de PPARα et diminue son expression protéique et que la surexpression de miR-21 diminue l'activité transcriptionnelle de PPARα. En outre, la surexpression et l'activation de PPARα diminuent l'expression de miR-21. En effet, PPARα interagit avec les facteurs de transcription AP-1 et NF-κB et empêche ainsi leur liaison au promoteur de miR-21 diminuant ainsi sa transcription.En conclusion, nous avons montré que (i) miR-21 est un acteur clé de la progression du cancer du rein et joue un rôle important dans la résistance aux chimiothérapies et (ii) qu'il existe une boucle de régulation négative entre miR-21 et PPARα dans le cRCC. / Renal clear cell carcinoma (cRCC) is the major histological type of renal carcinoma and one of the most chemo- and radio-resistant tumors. The absence of biomarkers for early detection and for monitoring patients is responsible of a poor prognosis. It is necessary to identify new biomarkers and therapeutic targets to improve patient care. MicroRNAs, small noncoding RNAs of 22 nucleotides, which have been previously shown to promote malignant initiation and progression, appear to be good candidates.We focused our study on (i) miR-21 which is the main overexpressed oncomirs in cRCC and (ii) the nuclear receptor PPARα (Peroxisome Proliferator Activated Receptor), one of miR-21 targets.In one hand, by using a cohort of 99 primary cRCC samples, we showed that miR-21 expression in cancer tissues was higher than in adjacent non-tumor tissues. In vitro, miR-21 was also overexpressed in renal carcinoma cell lines compared to HK-2 human proximal tubule epithelial cell line. Moreover, we also showed that miR-21 overexpression increased migratory, invasive, proliferative, and anti-apoptotic signaling pathways whereas opposite results were observed using an anti-miR-21-based silencing strategy. Finally, we assessed the role of miR-21 in mediating cRCC chemoresistance and further showed that miR-21 silencing significantly increased chemosensitivity of paclitaxel, 5-fluorouracil, oxaliplatin and dovitinib, decreased expression of multi-drug resistance genes and increased SLC22A1/OCT1, SLC22A2/OCT2 and SLC31A1/CTR1 platinum influx transporter expression. These results led to the publication of an article in Tumor Biology in annex.In other hand, in cRCC tissue patients, we showed for the first time that miR-21 overexpression correlates with a loss of expression of PPARα. In vitro, we showed that miR-21 targets PPARα 3'-UTR and decreases its protein expression and miR-21 overexpression decreases the transcriptional activity of PPARα. Furthermore, PPARα overexpression and activation decrease miR-21 expression. In fact, PPARα interacts with AP-1 and NF-kappaB transcription factors and thus prevents their binding to the miR-21 promoter thus decreasing its transcription.In conclusion, we have shown that (i) miR-21 is a key actor of renal cancer progression and plays an important role in the resistance to chemotherapeutic drugs and (ii) there is a negative regulatory loop between miR-21 and PPARα in cRCC.

Yuen, Yee Lok. / On t.p. "alpha" appears as the Greek letter. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 165-177). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iv / Acknowledgement --- p.vii / Table of Contents --- p.viii / List of Abbreviations --- p.xiii / List of Figures --- p.xv / List of Tables --- p.xx / Chapter Chapter 1 --- Literature review --- p.1 / Chapter 1.1 --- Peroxisome proliferator-activated receptor (PPAR) --- p.1 / Chapter 1.1.1 --- PPARα isoforms --- p.1 / Chapter 1.2 --- PPARα ligands --- p.2 / Chapter 1.3 --- Biological roles of PPARα --- p.3 / Chapter 1.3.1 --- Lipid metabolism --- p.3 / Chapter 1.3.2 --- Bile acid metabolism --- p.4 / Chapter 1.3.3 --- Biotransformation --- p.6 / Chapter 1.4 --- Roles of PPARα in hepatocarcinogenesis --- p.7 / Chapter 1.4.1 --- Cell proliferation and apoptosis --- p.7 / Chapter 1.4.2 --- Oxidative stress --- p.8 / Chapter 1.5 --- Discovery of novel PPARα target genes --- p.9 / Chapter 1.5.1 --- Identification of a novel PPARα-regulated gene L5#55 by fluorescent differential mRNA display (FDD) analysis --- p.9 / Chapter 1.6 --- Sulfotransferase (SULT) --- p.15 / Chapter 1.7 --- Objective of the present study --- p.16 / Chapter Chapter 2 --- Molecular cloning and characterization of mouse liver sulfotransferase-like (mL-STL) gene --- p.17 / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Materials and methods --- p.17 / Chapter 2.2.1 --- Animals --- p.17 / Chapter 2.2.2 --- Treatments --- p.18 / Chapter 2.2.3 --- Total RNA extraction --- p.18 / Chapter 2.2.3.1 --- Materials --- p.18 / Chapter 2.2.3.2 --- Methods --- p.19 / Chapter 2.2.4 --- Rapid amplification of cDNA ends (RACE) --- p.19 / Chapter 2.2.4.1 --- Materials --- p.19 / Chapter 2.2.4.2 --- Methods --- p.20 / Chapter 2.2.4.2.1 --- Primer design --- p.20 / Chapter 2.2.4.2.2 --- Rapid amplification of 5'- and 3'-cDNA ends --- p.20 / Chapter 2.2.5 --- Cloning of the 5'- and 3' RACE products --- p.25 / Chapter 2.2.5.1 --- Materials --- p.25 / Chapter 2.2.5.2 --- Methods --- p.25 / Chapter 2.2.6 --- Northern blot analysis --- p.28 / Chapter 2.2.6.1 --- Materials --- p.28 / Chapter 2.2.6.2 --- Methods --- p.28 / Chapter 2.2.6.2.1 --- Formaldehyde-agarose gel electrophoresis and blotting of RNA --- p.31 / Chapter 2.2.6.2.2 --- PCR DIG-labeling --- p.31 / Chapter 2.2.6.2.3 --- Hybridization and signal detection --- p.32 / Chapter 2.2.7 --- Reverse transcription (RT)-PCR --- p.34 / Chapter 2.2.7.1 --- Materials --- p.34 / Chapter 2.2.7.2 --- Methods --- p.34 / Chapter 2.3 --- Results and discussion --- p.37 / Chapter 2.3.1 --- Cloning of the full-length mL-STL cDNA --- p.37 / Chapter 2.3.2 --- In silico analysis of the mL-STL cDNAs --- p.50 / Chapter 2.3.3 --- Genomic organization of the mL-STL gene --- p.61 / Chapter 2.3.4 --- Tissue distribution of mL-STL mRNA transcript --- p.68 / Chapter 2.3.5 --- "PPARα-dependent regulation of mL-STL mRNA expression by fasting and Wy-14,643 treatment" --- p.74 / Chapter Chapter 3 --- Identification of the native mL-STL protein in mouse liver --- p.86 / Chapter 3.1 --- Introduction --- p.86 / Chapter 3.2 --- Materials and methods --- p.87 / Chapter 3.2.1 --- Animal and treatments --- p.87 / Chapter 3.2.2 --- Cloning of the mL-STL cDNA into a modified pRSET (mpRSET) expression vector --- p.88 / Chapter 3.2.2.1 --- Materials --- p.88 / Chapter 3.2.2.2 --- Methods --- p.88 / Chapter 3.2.2.2.1 --- Amplification of mL-STL cDNA fragments --- p.88 / Chapter 3.2.2.2.2 --- Preparation of mpRSET expression vector --- p.92 / Chapter 3.2.2.2.3 --- "Ligation, transformation, and screening of recombinants" --- p.92 / Chapter 3.2.3 --- Over-expression of the mL-STL recombinant proteins in E coli strains --- p.94 / Chapter 3.2.3.1 --- Materials --- p.94 / Chapter 3.2.3.2 --- Methods --- p.94 / Chapter 3.2.4 --- Mass spectrometry analysis of the mL-STL recombinant proteins --- p.95 / Chapter 3.2.4.1 --- Materials --- p.96 / Chapter 3.2.4.2 --- Methods --- p.96 / Chapter 3.2.4.2.1 --- Trypsin digestion and peptide extraction --- p.96 / Chapter 3.2.4.2.2 --- Matrix-assisted laser desorption/ionization time-of- flight (MALDI-TOF) mass spectrometry --- p.97 / Chapter 3.2.5 --- Purification of the mL-STL recombinant proteins --- p.98 / Chapter 3.2.5.1 --- Materials --- p.98 / Chapter 3.2.5.2 --- Methods --- p.98 / Chapter 3.2.5.2.1 --- Semi-purification of the mL-STL recombinant proteins by preparative SDS-PAGE --- p.98 / Chapter 3.2.5.2.2 --- Purification of mL-STL recombinant proteins by column chromatography --- p.99 / Chapter 3.2.6 --- Rabbit immunization using purified mL-STL recombinant proteins --- p.101 / Chapter 3.2.7 --- Subcellular fractionation of mouse liver by ultracentrifugation --- p.101 / Chapter 3.2.7.1 --- Materials --- p.101 / Chapter 3.2.7.2 --- Methods --- p.102 / Chapter 3.2.8 --- Western blot analysis of the native mL-STL protein --- p.104 / Chapter 3.2.8.1 --- Materials --- p.104 / Chapter 3.2.8.2 --- Methods --- p.104 / Chapter 3.2.8.2.1 --- SDS-PAGE and electro-blotting of proteins --- p.104 / Chapter 3.2.8.2.2 --- Immunostaining and signal detection --- p.105 / Chapter 3.3 --- Results and discussion --- p.106 / Chapter 3.3.1 --- Cloning of the mL-STLl and mL-STL2 cDNAs into a modified pRSET (mpRSET) vector --- p.106 / Chapter 3.3.2 --- IPTG induction of the mpRSET-mL-STL protein expression --- p.106 / Chapter 3.3.3 --- Confirmation of mL-STL recombinant proteins by mass spectrometry --- p.118 / Chapter 3.3.4 --- Purification of mL-STL recombinant proteins for rabbit immunization and polyclonal antisera production --- p.130 / Chapter 3.3.5 --- Antigenicity of mL-STL antisera --- p.134 / Chapter 3.3.6 --- Identification of mL-STL native protein and its induction pattern in mouse liver --- p.139 / Chapter 3.3.7 --- "Time-course of fasting and Wy-14,643 treatment on the mL- STLl native protein expression" --- p.147 / Chapter Chapter 4 --- Overall discussion --- p.153 / Future study --- p.163 / References --- p.165 / "Appendix A. Alignment of nucleotide sequences of mouse chromosome 7，Riken2810007J24, mL-STLl, and mL-STL2 cDNA sequences" --- p.178 / Appendix Bl. Theoretical tryptic peptide masses of mpRSET- mL-STLl protein --- p.217 / Appendix B2. Raw data from mass spectrometry analysis of mpRSET-mL-STLl protein --- p.218 / Appendix C1. Residue molecular mass of amino acids --- p.219 / Appendix C2. Di-peptide table --- p.220 / Appendix D1. Theoretical tryptic peptide masses of mpRSET- mL-STL2 protein --- p.221 / Appendix D2. Raw data from mass spectrometry analysis of mpRSET-mL-STL2 protein --- p.222

Xu, Jian. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 238-255). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016).

A la phase aiguë des accidents vasculaires cérébraux, les stratégies thérapeutiques reposent sur l'utilisation d'agents fibrinolytiques dont l'utilisation est limitée par une fenêtre thérapeutique étroite en raison du risque d'hémorragies intra-cérébrales lié à des altérations vasculaires et parenchymateuses. Cette approche fibrinolytique nécessiterait d'être complétée par une double protection de la paroi vasculaire et du parenchyme cérébral. Au sein de l'unité neurovasculaire, les leucocytes, et particulièrement les polynucléaires neutrophiles, jouent un rôle important dans l'inflammation, tant vasculaire que parenchymateuse qui conduit aux lésions cérébrales.<br />Ce travail a pour objectif de déterminer si dans un modèle d'ischémie cérébrale la modulation des interactions leucocytes-endothélium pourrait représenter une cible pertinente : (i) pour diminuer les conséquences lésionnelles de l'ischémie ; (ii) limiter le risque de complications hémorragiques de la thrombolyse. Ceci s'est fait par une double approche pharmacologique : (i) une modulation directe des polynucléaires neutrophiles ; (ii) une modulation des interactions par l'activation des récepteurs nucléaires PPAR-alpha.<br />Dans un premier temps, nos résultats suggèrent une contribution importante des leucocytes dans les altérations vasculaires post-ischémiques ainsi que dans la survenue des complications hémorragiques induites par la fibrinolyse. Dans la deuxième partie de notre travail, l'activation des récepteurs nucléaires PPAR-alpha prévient les altérations endothéliales vasculaires post-ischémiques parallèlement à un effet neuroprotecteur. Ces effets étaient associés à une diminution des complications hémorragiques et du recrutement leucocytaire au sein du foyer ischémique.<br />En conclusion, la protection neurovasculaire après une ischémie cérébrale suivie ou non d'une fibrinolyse apparaît comme une cible intéressante susceptible de prévenir la maturation de l'ischémie cérébrale et les complications hémorragiques. Les récepteurs nucléaires PPAR-alpha représentent expérimentalement une stratégie thérapeutique potentielle de protection de la paroi vasculaire et du tissu cérébral en modulant les interactions leucocytes-endothélium

L'épilepsie affecte environ 1% de la population. Il s'agit d'une maladie où les crises d'épilepsie surviennent de façon spontanée et imprévue. La prise en charge de ces crises peut se faire par des antiépileptiques, mais dans environ 20 à 30% des cas, les épilepsies ne répondent pas ou peu aux médicaments. Il s'agit alors d'épilepsies pharmacorésistantes. Un des traitements de recours utilisé pour la prise en charge de ces épilepsies est le régime cétogène. Le régime cétogène consiste à apporter une large quantité de lipides, pour une faible quantité de protéines et de glucides. Le régime possède des propriétés anticonvulsivantes, décrites chez l'Homme et le rongeur, mais les mécanismes d'action restent inconnus à ce jour. Plusieurs mécanismes ont été suggérés tels que : les propriétés anticonvulsivantes des corps cétoniques, la modulation de la neurotransmission, la modulation de l'excitabilité cérébrale via la modulation de canaux ioniques tels que les KATP. L'implication des acides gras poly-insaturés (AGPI) a également été suggérée. Ceux-ci pourraient moduler la fluidité membranaire, l'activité des canaux ioniques ou encore les voies de l'inflammation. Notre hypothèse de travail a été d'explorer des voies supposées être impliquées dans les propriétés anticonvulsivantes du régime cétogène. Nous nous sommes intéressés aux AGPI et à l'activation des récepteurs nucléaires PPAR-alpha (peroxisome proliferator-activated receptor alpha) en comparaison au régime cétogène. Nous avons utilisé un modèle murin d'état de mal épileptique (lithium-pilocarpine) et l'induction de crises épileptiques avec mesure du seuil au pentylènetétrazole.<br />Dans un premier temps, nous avons administré per-os, pendant 4 semaines un mélange d'AGPI contenant 70% d'oméga-3 et 25% d'oméga-6 à des rats Wistar. Les animaux ayant reçu la complémentation alimentaire par des AGPI présentaient une augmentation du seuil au PTZ comparable à celle obtenue chez les animaux ayant reçu un régime cétogène. Les animaux supplémentés par les AGPI ou ayant reçu le régime cétogène présentaient des variations plasmatiques en AGPI concernant l'acide arachidonique, l'acide alpha linolénique et l'acide eicosapentaenoïque. Aucune modification du statut nutritionnel ou des phospholipides cérébraux membranaires n'était retrouvée. Dans un second temps, nous avons administré pendant 14 jours de la nourriture contenant 0,2% de fénofibrate (agoniste des récepteurs PPAR-alpha) à des rats Wistar. Le traitement par 0,2% de fénofibrate conduisait à augmenter le seuil au PTZ et retarder le début de l'état de mal épileptique dans le modèle lithium-pilocarpine. Ces résultats étaient comparables à ceux obtenus avec le régime cétogène. En revanche le traitement associant le régime cétogène et le fénofibrate ne conduisait pas à moduler le seuil au PTZ chez les animaux.<br />Ces travaux ont permis de montrer que les AGPI ont des propriétés anticonvulsivantes, comparables à celles du régime cétogène. Ces propriétés anticonvulsivantes ont également été retrouvées suite à l'activation des récepteurs nucléaires PPAR-alpha par le fénofibrate. Les propriétés anticonvulsivantes portées par les AGPI ne sont pas liées à une variation de la composition des membranes cellulaires cérébrales en phospholipides. Les récepteurs nucléaires PPAR-alpha modulent quant à eux de nombreuses voies (métaboliques, inflammatoires, stress oxydant) via des variations d'expression génique et peuvent être activés par les AGPI. L'implication de ces différentes voies dans l'efficacité anticonvulsivante du fénofibrate, reste à explorer. Ces résultats, s'ils sont confirmés par des études complémentaires dans d'autres modèles, laissent penser qu'une simplification du régime cétogène pourrait être envisagée via l'utilisation des AGPI et/ou via l'activation des récepteurs nucléaires PPAR-alpha

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