Comment citer ce document :
Nguyen, C., Coelho, A.-M., Grady, E., Compton, S. J., Wallace , J. L., Hollenberg, M. D., Cenac, N., Garcia Villar, R., Bueno, L., Steinhoff, M., Bunnett, N. W., Vergnolle, N. (2003). Colitis induced by proteinase-activatedreceptor-2 agonists is mediated by a neurogenic mechanism.
iNOS activity was determined in the presence of a calcium chelator, eth- ylene-glycol-bis( ␣-aminoethyl)-N,N,N⬘,N⬘-tetraacetic acid (EGTA, 1 mM). Nonspecific activity was determined in the presence of 1 mM EGTA and 20 mM L -NAME, a nonisoform specific NOS inhibitor. After 30 min of incubation at 37°C, the enzymatic reaction was stopped by adding cold HEPES buffer (pH 5.5) containing 1 mM EGTA and 1 mM EDTA. L - citrulline formed in the medium was separated by applying the samples to columns containing pre-equilibrated Dowex AG50W-X8 (Sigma-Aldrich, St. Quentin Fallavier, France), eluting them with water, and measuring the amount of radioactivity with a liquid scintillation beta counter (Kontron Instruments, St Quentin en Yvelines, France). Total NOS specific (i.e., iNOS ⫹ constitutive NOS (cNOS)) activity was determined by the difference between the L -citrulline generated in samples containing 2 mM CaCl 2 and samples containing 1 mM EGTA and 20 mM L -NAME;
To further assess the aggravated cartilage breakdown in GPR40 knock-out mice compared to wild-type mice, we analyzed the expression of a wide range of key markers implicated in OA after eight weeks of induction (Figure 4). Using quantitative PCR, we first determined the expres- sion of inflammatory factors (Figure 4a). PMMx GPR40 / joints showed a slightly increased expression of IL-6 (1.54 fold-change), inducible iNOS (1.44 fold-change) and cyclooxygenase COX-2 (1.58 fold-change), and a significant elevation of TNF-a expression (1.78 fold-change, P ¼ 0.02) compared to PMMx GPR40 þ/þ joints (Figure 4a). Overall the inflammatory level measured in GPR40 / knees was higher than in GPR40 þ/þ . In addition to inflammation, we observed an elevated expression of catabolic enzymes such as MMP-2 (1.44 fold-change, P ¼ 0.04), ADAMST4 (1.72 fold-change) and ADAMST5 (1.65 fold-change, P ¼ 0.01) in GPR40 deficient joints (Figure 4b). Cartilage anabolism was also investigated and we showed an increase of COMP and collagen X expressions in PMMx groups compared to sham-operated groups (Figure 4c). However, we noted that the fold-changes measured between PMMx and Sham groups were lower in GPR40 / knees than in GPR40 þ/þ knees (1.28 versus 1.79, P ¼ 0.04 for COMP and 1.28 versus 1.8, P ¼ 0.16 for ColX, respectively). In addition, the expres- sion of collagen type 2 was significantly lower in GPR40 /
In our mouse model, inhibition of PAR1 activation using the antagonist SCH79797 was clearly beneficial by decreasing the severity of hMPV disease. Most strikingly, when treatment was started simultaneously with hMPV-infection and was continued for 5 days, no weight loss or clinical signs were observed (Figure 2). Evaluation of pulmonary inflammation and viral titers was performed on day 5 pi, the time point at which both parameters peak in untreated hMPV-infected mice . During this acute phase of infection, pulmonary inflammation mostly consists of interstitial, perivascular and alveolar inflammation and all these parameters were significantly reduced by treatment with the PAR1 antagonist. In line with this observation, we also showed a significant reduction in the levels of key cytokines/chemokines that are usually increased in hMPV infection (including IFN-γ, IL-6, KC, MCP-1, MIP-1α and RANTES) . Some of these cytokines namely IL-6, IL-8 (the human equivalent of murine KC) and MCP-1 have been previously shown to be up-regulated by PAR1 activation or down-regulated by PAR1 inhibition in non-infected human respiratory epithelial cells in models of asthma and idiopathic pulmonary fibrosis [61–64]. Furthermore, SCH79797 significantly reduced MCP-1 expression in M. tuberculosis H37Rv-infected cells in vitro . Finally, Khoufache et al. recently demonstrated that SCH79797 treatment of influenza A-infected mice also significantly reduced IL-6, KC and RANTES levels in broncho-alveolar lavages .
cellular activation. Based on previous studies on the human IL-1Ra promoter, one can suggest that rosiglita- zone could have affected alternate IL-1–sensitive trans- acting factors such as CCAAT/enhancer binding pro- teins or activator protein 1 (60,61).
Second, we searched for the possible contribution of PPAR / , since high-dose rosiglitazone was shown to activate the PPAR-responsive promoter in cells express- ing PPAR / but not PPAR (19), whereas it inhibited inflammatory genes through activation of the PPAR / isotype in macrophages (62). This hypothesis was further supported by the inability of other PPAR (troglita- zone) and PPAR (Wy-14,643) agonists to affect IL-1 – induced IL-1Ra production. We demonstrated that PPAR / was expressed constitutively in synovial fibro- blasts, both at the mRNA and protein levels, and that its expression was not changed by cellular activation. In contrast, we showed that PPAR level decreased dra- matically in activated synoviocytes, thus confirming that this isotype was regulated negatively by inflammatory stimuli in articular cells (28). Such low levels of PPAR in inflammatory conditions would likely favor the bind- ing of rosiglitazone to PPAR / , despite its low affinity for this isotype (55). Consistent with a PPAR / - dependent mechanism, we demonstrated that induction of IL-1Ra secretion by rosiglitazone was abolished by transfection with a dominant-negative form of PPAR / . We showed further that a low concentration of GW-501516, a highly selective PPAR / agonist (27,63,64), reproduced the stimulating effect of high- dose rosiglitazone on IL-1Ra secretion. Taken together, these data demonstrate that rosiglitazone enhanced IL-1Ra secretion in a PPAR / -dependent manner and that this likely occurred because its relative affinity for PPAR isotypes was counterbalanced by the pattern of expression of PPAR isotypes in response t o IL-1 stimulation.
The PPAR subfamily of nuclear receptors comprises three isotypes: PPARα, PPARβ/δ and PPARγ, each encoded by separate genes and with a unique albeit overlapping tissue distribution. These three isotypes share a common structural organization, namely, a variable N-terminal domain with a ligand-independent activation function, a conserved DNA binding domain, and a C-terminal ligand-binding domain, which con- tains the ligand-dependent activation function 2 (AF2) (Fig. 3 ) [ 95 ]. Attention has focused on PPARα given that (1) it is highly prevalent in metabolically active tissues such as the liver, kidney, heart, muscle, brown adipose, and macrophages, and (2) has a key role in transcriptional regulation of lipoprotein metabolism, specifically fatty acid transport and beta-oxidation, as well as vascular inflammation [ 95 ]. Hepatic PPARα agonism accounts for most of these effects. Under cir- cumstances of diminished hepatic PPARα function, PPARα-dependent regulation of fatty acid oxidation in peripheral tissues may also become relevant [ 96 ].
Figure 1. RSV inhibits colon cancer cell survival through a PPARγ pathway. (A) After 24 h of culture, colon cancer cell lines, HCT-116, Caco-2 and SW480 and their metastatic phenotype SW620 cells were left untreated (Co, 0.1% ethanol) or treated with RSV at 30 µM (R30) with or without GW9662 at 2.5 (GW2.5) or 5 (GW5) µM for the indicated times, and the percentage of cell survival was determined using trypan blue exclusion. (B) SW480 cells were transiently transfected with either an empty plasmid (pcDNA3) or a plasmid encoding a double dominant-negative mutant of PPARγ (PPARγ/DN). Twenty-four hours later, cells were treated with either 30 µM of RSV (R30) or with the vehicle (Co, 0.1% ethanol) for 48 h before measuring cell survival. (C) SW480 cells were left untreated (black bars) or treated with RSV at 30 µM (R30) (white bars) with or without the PPARα antagonist, GW6471 or the PPARβ/δ antagonist, GSK0660 at indicated concentrations (0–5 µM) for 48 h. Cell survival was measured by trypan blue exclusion. All panels: mean ± SD (n=6) of three independent experiments; *, p<0.05 and **, p<0.001.
Riu et al.
estrogenic activity of chlorinated congeners could be similar to or higher than that of BPA (Mutou et al. 2006; Takemura et al. 2005). Similarly, both TBBPA and TCBPA interact with and disrupt thyroid hormone receptor signaling (Kitamura et al. 2002). Recently, Somm et al. (2009) showed that peri natal exposure to BPA altered early adipogenesis in the rat, which is mediated by peroxisome proliferator–activatedreceptor γ (PPARγ), a nuclear hormone receptor whose dysregulation is involved in the onset of diabetes and obesity (Swedenborg et al. 2009). This suggests that BPA and its derivatives may also interact with this receptor. In the present study, we exam ined the capacity of BPA and halogenated BPA derivatives to inter act with and perturb signaling by ERα, ERβ, PPARα, PPARδ, and PPARγ. We provide the first experimental evidence that flame retardants TBBPA and TCBPA are ligands and partial agonists of human PPARγ and also activate the corre sponding zebrafish and Xenopus receptors. Our findings indicate that these compounds should certainly be evaluated as EDCs with possible deleterious effects on humans and wildlife.
uated the secretion of proinflammatory cytokines in response to fibrilar A␤. Furthermore, the conditioned medium of these stim- ulated microglia was neurotoxic, whereas the medium from mi- croglia stimulated with A␤ but treated with NSAIDs displayed a protective effect in neurons (Klegeris et al., 1999; Combs et al., 2000). Interestingly, the thiazolidinedione (TZD) drugs (Willson et al., 2000), agonists of the peroxisome proliferator-activatedreceptor ␥ (PPAR␥), showed the same anti-inflammatory neuro- protective effect as NSAIDs (Combs et al., 2000). Because some NSAIDs are agonists of PPAR␥ (Lehmann et al., 1995), and given the evidence for a direct role of NSAIDs on amyloid pathology (Lim et al., 2000; Weggen et al., 2001; Jantzen et al., 2002; Q. Yan et al., 2003), the possible role of PPAR ␥ in this context deserves additional investigation. PPAR␥ is a nuclear transcription factor belonging to the PPAR family. These transcription factors play important physiological roles in the regulation of lipid metabo- lism (Mangelsdorf et al., 1995; Lemberger et al., 1996). PPAR␥ is involved in adipocyte differentiation (Chawla et al., 1994; Ton- tonoz et al., 1994; Hu et al., 1995; Rosen et al., 1999), insulin action (Olefsky, 2000; Steppan et al., 2001), and cell proliferation (Wang et al., 2001; Okano et al., 2002). The recent discovery that PPAR ␥ stimulation reduces inflammation in vitro (Lemberger et al., 1996; Colville-Nash et al., 1998; Jiang et al., 1998; Petrova et al., 1999; Ricote et al., 1999; Combs et al., 2000) and in vivo (Heneka et al., 2000; Dehmer et al., 2004), together with the fact that PPAR␥ agonists (Willson et al., 2000) have been used for years in the treatment of diabetes type II, have raised the hope that PPAR␥ could become a drug target for the treatment of neurological diseases with an inflammatory component-like AD. Based on the NSAID studies mentioned above, we speculated that activation of PPAR␥ could have, in addition to its well known
ALK (anaplastic lymphoma kinase) is a receptor tyrosine kinase, initially discovered as part of the NPM-ALK fusion protein, resulting from the t(2 ;5) translocation that is frequently associated with anaplastic large cell lymphomas. The native ALK protein is normally expressed in the developing and, at a weaker level, adult nervous system. We recently demonstrated that the oncogenic, constitutively kinase activated NPM-ALK protein was antiapoptotic when expressed in Jurkat lymphoblastic cells treated with cytotoxic drugs. In contrast, we now show that Jurkat cells overexpressing the wild type ALK receptor are more sensitive to doxorubicin-induced apoptosis than parental cells. Moreover, the ALK protein is cleaved during apoptosis in a caspase-dependent manner. Mutation of aspartic residues to asparagine allowed us to map the caspase cleavage site in the juxta-membrane region of ALK. In order to assess the role of ALK in a neural derived tissue, we transiently expressed ALK in the 13.S.1.24 rat neuroblast immortalized cell line. ALK expression led to apoptotic cell death of the neuroblasts. ALK ligation by specific activating antibodies decreased ALK-facilitated apoptosis in both lymphoid and neuronal cell lines. Moreover, ALK transfection reduced the survival of primary cultures of cortical neurons. Thus, ALK has a proapoptotic activity in the absence of ligand, whereas it is antiapoptotic in the presence of its ligand and when the kinase is intrinsically activated. These properties place ALK in the growing family of dependence receptors.
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 4 Institute for Theoretical Physics, University of Göttingen, D-37077, Göttingen, Germany
(Dated: November 19, 2019)
Perturbations of fluid media can give rise to non-equilibrium dynamics, which may in turn cause motion of immersed inclusions. We consider perturbations (“activations”) that are local in space and time, of a fluid density which is conserved, and study the resulting diffusiophoretic phenomena that emerge at a large distance. Specifically, we consider cases where the perturbations propagate diffusively, providing examples from passive and active matter for which this is expected to be the case. Activations can, for instance, be realized by sudden and local changes in interaction potentials of the medium, or by local changes of its activity. Various analytical results are provided for the case of confinement by two parallel walls. We investigate the possibility of extracting work from inclusions which are moving through the activated fluid. Further, we show that a time-dependent density profile, created via suitable activation protocols, allows for conveyance of inclusions along controlled and stable trajectories. In contrast, in states with a steady density, inclusions cannot be held at stable positions, reminiscent of Earnshaw’s theorem of electrostatics. We expect these findings to be applicable in a range of experimental systems.
Prostate cancer is the most common form of cancer in men, and the second leading cause of 15
cancer deaths. Tumor growth is originally androgen dependent. Androgens exert their effects through activation of the Androgen receptor (AR), a member of the hormone nuclear receptor superfamily. In the mature prostatic gland, AR regulates the expression of genes involved in cell division and proliferation of the epithelial cells (26). AR is also involved in several other aspects of prostate cellular metabolism, including lipid biosynthesis and controls the production of 20
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PPAR activation increases 11 -HSD1 activity in M2 macrophages leading to the induction of GR-target genes by cortisone γ β
RM (A) , M1 (B) and M2 (C) macrophages were treated for 24h in the absence or in the presence of GW1929 (600nM) and subsequently incubated with radio-labelled cortisone (E) for the indicated time periods. Production of cortisol (F) was then measured. 11 -HSD1 reductase β activity was determined as the percentage conversion of cortisone to cortisol. Results are representative of two independent experiments. Statistically significant differences between control and treated cells are indicated ( p<0.05). RM and M2 macrophages were activated or not * with GW1929 (600nM) for 24h and subsequently treated for another 24h with cortisone (1 M). PDK4 μ (D) , GILZ (E) and ANGPTL4 (F)
Kuiken, T., Riteau, B., Fouchier, R.A., Rimmelzwaan, G.F., 2012. Pathogenesis of influenza
virus infections: the good, the bad and the ugly. Curr Opin Virol 2, 276-286.
Le, V.B., Schneider, J.G., Boergeling, Y., Berri, F., Ducatez, M., Guerin, J.L., Adrian, I.,
Errazuriz-Cerda, E., Frasquilho, S., Antunes, L., Lina, B., Bordet, J.C., Jandrot-Perrus, M.,
Diabetes & Metabolism 40 (2014) S1-S3
Type 2 diabetes is among the most important and preva- lent chronic diseases, and any novel therapy that is able to address chronic hyperglycaemia is welcome as another tool for clinicians to help prevent the development of diabetic complications . It is widely recommended that, if lifestyle interventions are inadequate, the first line of drug treatment is metformin, followed by a sulphonylurea, a glitazone, a dipeptidyl peptidase (DPP)-4 inhibitor or even a glucagon- like peptide (GLP)-1 analogue, before starting insulin . However, every antidiabetic drug class has its own side-effects and limitations, including metformin . Sulphonylureas, glitazones and insulin all cause weight gain, which can worsen insulin resistance. Sulphonylureas and insulin can also cause hypoglycaemia, while pioglitazone can induce oedema, heart failure and bone fractures . These limitations of the classical glucose-lowering therapies have paved the way towards the development and success of incretin-based therapies for the management of hyperglycaemia in type 2 diabetes. However, beyond the potential safety issues, a major drawback of DPP-4 inhibitors (and, to a lesser extent, of GLP-1 analogues) is that a substantial proportion of diabetic patients will not respond sufficiently to these drugs and, thus, will fail to achieve glycated haemoglobin (HbA 1c ) targets. Therefore, diabetologists clearly need novel therapies with higher rates of clinical response, while the complexity of type 2 diabetes probably also requires combined therapies in most cases.
Bicyclic petasite eremophilane-type
sesquiterpenes potentiate the effects of PPARγ agonists on BmDC maturation and activation
Petasite sesquiterpenes have been shown to have anti-inflammatory activity in a variety of settings. We sought to assess the effects of two petasite ere- mophilane-type sesquiterpene compounds Fukinone (ZYFDC21) and 10βH-8α,12-Epidioxyeremophil- 7(11)-en-8β-ol (ZYFDC22) isolated from the rhi- zome of P. tatewakianus on the maturation and activation of BmDCs. To evaluate the cytotoxic effects of the bicyclic compounds, we performed dose-response assays with several cell lines, using the XTT assay kit (Roche, data not shown). We selected sub-toxic doses of ZYFDC21 (50 µM) and ZYFDC22 (25 µM) and further evaluated their cyto- toxic effects on BmDC after 1, 3, 24 and 48 h incu- bation, measuring viability by trypan blue exclusion (supplementary Figure 2). BmDC viability was ⩾95% under all tested conditions, and therefore, these concentrations were used for all experiments.