84 research outputs found
All-trans retinoic acid suppresses interleukin-6 expression in interleukin-1-stimulated synovial fibroblasts by inhibition of ERK1/2 pathway independently of RAR activation
International audienc
Inorganic pyrophosphate generation by transforming growth factor-beta-1 is mainly dependent on ANK induction by Ras/Raf-1/extracellular signal-regulated kinase pathways in chondrocytes
ANK is a multipass transmembrane protein transporter thought to play a role in the export of intracellular inorganic pyrophosphate and so to contribute to the pathophysiology of chondrocalcinosis. As transforming growth factor-beta-1 (TGF-β1) was shown to favor calcium pyrophosphate dihydrate deposition, we investigated the contribution of ANK to the production of extracellular inorganic pyrophosphate (ePPi) by chondrocytes and the signaling pathways involved in the regulation of Ank expression by TGF-β1. Chondrocytes were exposed to 10 ng/mL of TGF-β1, and Ank expression was measured by quantitative polymerase chain reaction and Western blot. ePPi was quantified in cell supernatants. RNA silencing was used to define the respective roles of Ank and PC-1 in TGF-β1-induced ePPi generation. Finally, selective kinase inhibitors and dominant-negative/overexpression plasmid strategies were used to explore the contribution of several signaling pathways to Ank induction by TGF-β1. TGF-β1 strongly increased Ank expression at the mRNA and protein levels, as well as ePPi production. Using small interfering RNA technology, we showed that Ank contributed approximately 60% and PC-1 nearly 20% to TGF-β1-induced ePPi generation. Induction of Ank by TGF-β1 required activation of the extracellular signal-regulated kinase (ERK) pathway but not of p38-mitogen-activated protein kinase or of protein kinase A. In line with the general protein kinase C (PKC) inhibitor calphostin C, Gö6976 (a Ca2+-dependent PKC inhibitor) diminished TGF-β1-induced Ank expression by 60%, whereas a 10% inhibition was observed with rottlerin (a PKCδ inhibitor). These data suggest a regulatory role for calcium in TGF-β1-induced Ank expression. Finally, we demonstrated that the stimulatory effect of TGF-β1 on Ank expression was inhibited by the suppression of the Ras/Raf-1 pathway, while being enhanced by their constitutive activation. Transient overexpression of Smad 7, an inhibitory Smad, failed to affect the inducing effect of TGF-β1 on Ank mRNA level. These data show that TGF-β1 increases ePPi levels, mainly by the induction of the Ank gene, which requires activation of Ras, Raf-1, ERK, and Ca2+-dependent PKC pathways in chondrocytes
Anti-inflammatory effect of antidiabetic thiazolidinediones prevents bone resorption rather than cartilage changes in experimental polyarthritis
Contrasting effects of peroxisome-proliferator-activated receptor (PPAR)γ agonists on membrane-associated prostaglandin E(2 )synthase-1 in IL-1β-stimulated rat chondrocytes: evidence for PPARγ-independent inhibition by 15-deoxy-Δ(12,14)prostaglandin J(2)
Microsomal prostaglandin E synthase (mPGES)-1 is a newly identified inducible enzyme of the arachidonic acid cascade with a key function in prostaglandin (PG)E(2 )synthesis. We investigated the kinetics of inducible cyclo-oxygenase (COX)-2 and mPGES-1 expression with respect to the production of 6-keto-PGF(1α )and PGE(2 )in rat chondrocytes stimulated with 10 ng/ml IL-1β, and compared their modulation by peroxisome-proliferator-activated receptor (PPAR)γ agonists. Real-time PCR analysis showed that IL-1β induced COX-2 expression maximally (37-fold) at 12 hours and mPGES-1 expression maximally (68-fold) at 24 hours. Levels of 6-keto-PGF(1α )and PGE(2 )peaked 24 hours after stimulation with IL-1β; the induction of PGE(2 )was greater (11-fold versus 70-fold, respectively). The cyclopentenone 15-deoxy-Δ(12,14)prostaglandin J(2 )(15d-PGJ(2)) decreased prostaglandin synthesis in a dose-dependent manner (0.1 to 10 μM), with more potency on PGE(2 )level than on 6-keto-PGF(1α )level (-90% versus -66% at 10 μM). A high dose of 15d-PGJ(2 )partly decreased COX-2 expression but decreased mPGES-1 expression almost completely at both the mRNA and protein levels. Rosiglitazone was poorly effective on these parameters even at 10 μM. Inhibitory effects of 10 μM 15d-PGJ(2 )were neither reduced by PPARγ blockade with GW-9662 nor enhanced by PPARγ overexpression, supporting a PPARγ-independent mechanism. EMSA and TransAM(® )analyses demonstrated that mutated IκBα almost completely suppressed the stimulating effect of IL-1β on mPGES-1 expression and PGE(2 )production, whereas 15d-PGJ(2 )inhibited NF-κB transactivation. These data demonstrate the following in IL-1-stimulated rat chondrocytes: first, mPGES-1 is rate limiting for PGE(2 )synthesis; second, activation of the prostaglandin cascade requires NF-κB activation; third, 15d-PGJ(2 )strongly inhibits the synthesis of prostaglandins, in contrast with rosiglitazone; fourth, inhibition by 15d-PGJ(2 )occurs independently of PPARγ through inhibition of the NF-κB pathway; fifth, mPGES-1 is the main target of 15d-PGJ(2)
Impact of the Exposome on the Epigenome in Inflammatory Bowel Disease Patients and Animal Models
peer reviewedInflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract that encompass two main phenotypes, namely Crohn’s disease and ulcerative colitis. These conditions occur in genetically predisposed individuals in response to environmental factors. Epigenetics, acting by DNA methylation, post-translational histones modifications or by non-coding RNAs, could explain how the exposome (or all environmental influences over the life course, from conception to death) could influence the gene expression to contribute to intestinal inflammation. We performed a scoping search using Medline to identify all the elements of the exposome that may play a role in intestinal inflammation through epigenetic modifications, as well as the underlying mechanisms. The environmental factors epigenetically influencing the occurrence of intestinal inflammation are the maternal lifestyle (mainly diet, the occurrence of infection during pregnancy and smoking); breastfeeding; microbiota; diet (including a low-fiber diet, high-fat diet and deficiency in micronutrients); smoking habits, vitamin D and drugs (e.g., IBD treatments, antibiotics and probiotics). Influenced by both microbiota and diet, short-chain fatty acids are gut microbiota-derived metabolites resulting from the anaerobic fermentation of non-digestible dietary fibers, playing an epigenetically mediated role in the integrity of the epithelial barrier and in the defense against invading microorganisms. Although the impact of some environmental factors has been identified, the exposome-induced epimutations in IBD remain a largely underexplored field. How these environmental exposures induce epigenetic modifications (in terms of duration, frequency and the timing at which they occur) and how other environmental factors associated with IBD modulate epigenetics deserve to be further investigated
Lack of Adipocytes Alters Hematopoiesis in Lipodystrophic Mice.
Adult hematopoiesis takes place in the perivascular zone of the bone cavity, where endothelial cells, mesenchymal stromal/stem cells and their derivatives such as osteoblasts are key components of bone marrow (BM) niches. Defining the contribution of BM adipocytes to the hematopoietic stem cell niche remains controversial. While an excess of medullar adiposity is generally considered deleterious for hematopoiesis, an active role for adipocytes in shaping the niche has also been proposed. We thus investigated the consequences of total adipocyte deletion, including in the BM niche, on adult hematopoiesis using mice carrying a constitutive deletion of the gene coding for the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ). We show that Pparg <sup>Δ/Δ</sup> lipodystrophic mice exhibit severe extramedullary hematopoiesis (EMH), which we found to be non-cell autonomous, as it is reproduced when wild-type donor BM cells are transferred into Pparg <sup>Δ/Δ</sup> recipients. This phenotype is not due to a specific alteration linked to Pparg deletion, such as chronic inflammation, since it is also found in AZIP <sup>tg/+</sup> mice, another lipodystrophic mouse model with normal PPARγ expression, that display only very moderate levels of inflammation. In both models, the lack of adipocytes alters subpopulations of both myeloid and lymphoid cells. The CXCL12/CXCR4 axis in the BM is also dysregulated in an adipocyte deprived environment supporting the hypothesis that adipocytes are required for normal hematopoietic stem cell mobilization or retention. Altogether, these data suggest an important role for adipocytes, and possibly for the molecular interactions they provide within the BM, in maintaining the appropriate microenvironment for hematopoietic homeostasis
Prise en compte de la gestion des risques liés à l'utilisation du MEOPA dès la conception des locaux (proposition d'un cahier des charges fonctionnel pour une approche pluridisciplinaire)
NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF
Place de l'ézétimibe ezetrol® dans la stratégie thérapeutique normolipémiante
NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF
Intérêts de l'approche pharmacoépidémiologique dans l'étude des effets indésirables inattendus en population (exemples récents observés avec les vaccins)
NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF
Etude des potentialités des agonistes des récepteurs activés par les proliférateurs de péroxysomes (PPAR) sur les réponses chondrocytaires induites par le transforming growth factor beta (TGF-b)
[Résumé en français] Considérant les effets bi-potentiels du TGF-b1 et les effets anti-fibrotiques des agonistes PPAR dans divers tissus d'origine non articulaire, le but de cette thèse est d'étudier la capacité de certains agonistes des trois isotypes PPAR (a, b/ et g) à contrecarrer les réponses métaboliques induites par le TGF-b1 dans les chondrocytes de rat. Dans ce rapport, nous démontrons que l'alginate constitue un système de culture optimal. De plus, au moyen d'un panel de gènes cibles spécifiques des PPAR, nous démontrons que le Wy14643, le GW501516, et la rosiglitazone induisent préférentiellement des réponses dépendantes de PPARa, b/ et g respectivement, alors que la pioglitazone induit des réponses dépendantes de PPAR" g>a". En présence de TGF-b1, nous montrons que les tous agonistes réduisent la biosynthèse des protéoglycanes ou des collagènes via une inhibition précoce et/ou tardive des voies dépendantes de Smad2/3, ERK1/2 et PGE2. Nous démontrons aussi que les agonistes régulent le turnover de la matrice extracellulaire et inhibent les activités cruciales pour la biosynthèse des composants matriciels en restaurant l'activité des MMPs. Ces régulations sont dépendantes du profil de sélectivité de chaque agoniste. Ceci suggère que la part de chondroprotection, fournie par les agonistes via une diminution de la production des cytokines pro-inflammatoires, semble être diminuée par une réduction de la sensibilité des chondrocytes à certains facteurs de croissance. Nos résultats sous-tendent une complexité des mécanismes mis en jeu qui nécessitent davantage d'investigations vis-à-vis du rôle du TGF-b1 et des PPAR au sein même de l'articulation.[Résumé en anglais] When considering the bipotential effects of TGF-b1 and the antifibrotic effect associated with PPAR activation in many organs, we investigated the ability of synthetic PPAR agonists of the three isotypes (a, b/ and g) to affect TGF-b1-induced metabolism responses in rat chondrocytes. ln our report, we choose alginate as the optimal culture system. ln addition, using a panel of PPAR target genes, we demonstrate that Wy14643, GW501516 and rosiglitazone induced preferentially a-, b/ - and g-dependent responses respectively, while pioglitazone induced "g >a responses. Moreover, the stimulating effect of TGF-b1 on proteoglycans or collagens synthesis is reduced dramatically by all PPAR agonists via early and/or tardive inhibitions of Smads, ERK1/2 and/or PGE2 pathways. This could suggest that PPAR agonists inhibit crucial activities and regulate extracellular matrix (ECM) turnover biosynthesis by restoring MMPs activities. These regulations were found to be dependant of the selectivity profile of each agonist in rat chondrocytes. Taken all together, our data demonstrate that PPAR agonists reduce TGF-b1-induced responses in rat chondrocytes and may favour an altered repair capacity of cartilage in response to some articular joint growth factors, like TGF-b. Due to the complexity of the involved mechanisms related to the physiopathological role of TGF-b1 and to the lack of chondroprotection provided by PPAR agonists in cartilage, further studies are required.NANCY1-SCD Medecine (545472101) / SudocSudocFranceF
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