996 resultados para Factor Prevents
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The aim of this study is to evaluate whether aspirin reduces Diabetis Mellitus (DM) oxidative damage in the lacrimal gland (LG), and ocular surface (OS). Ten weeks after streptozotocin induced DM and aspirin treatment, LG and OS of rats were compared for tear secretion, hidtology, peroxidase activity, and expression of uncoupling proteins (UCPs). DM reduction of tear secretion was prevented by aspirin (P < 0.01). Alterations of LG morphology and increased numbers of lipofucsin-like inclusions were observed in diabetic but not in aspirin-treated diabetic rats. Peroxidase activity levels were higher and UCP-2 was reduced in DM LG but not in aspirin treated (P = 0.0025 and P < 0.05, respectively). The findings prevented by aspirin indicate a direct inhibitory effect on oxidative pathways in LG and their inflammatory consequences, preserving the LG structure and function against hyperglycemia and/or insulin deficiency damage.
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Activated monocytes and macrophages secrete the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) TNF-alpha is produced as a 26 kd transmembrane protein that is cleaved to release a 17 kd soluble protein. TNF-alpha in both forms is biologically active. The intracellular trafficking of membrane-associated TNF-alpha in lipopolysaccharide-activated mouse macrophages was assessed after treatment with the metalloprotease inhibitor BB-3103, which prevents the cleavage of pro-TNF-alpha. Immunoprecipitation and immunofluorescence studies showed sustained expression of cell-associated TNF-alpha in the presence of the inhibitor. Cell immunoreactivity and surface biotinylation revealed that uncleaved TNF-alpha accumulated on the cell surface and was endocytosed, appearing in intracellular vesicles. Perturbation of post-Golgi traffic blocked the surface expression of 26 kd TNF-alpha. Tracking a bolus of TNF-alpha over time in cycloheximide-treated cells confirmed that uncleaved TNF-alpha is first transported to the cell surface and subsequently endocytosed. Vesicular structures immunoreactive for TNF-alpha were identified as endosomes by double labeling. The secretory and membrane-associated endocytic trafficking of TNF-alpha provides a mechanism for modulating the quantity of biologically active 26 kd TNF-alpha expressed on macrophages, allowing regulation of paracrine and autocrine responses.
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OBJECTIVE To establish the role of the transcription factor Pax4 in pancreatic islet expansion and survival in response to physiological stress and its impact on glucose metabolism, we generated transgenic mice conditionally and selectively overexpressing Pax4 or a diabetes-linked mutant variant (Pax4R129 W) in β-cells. RESEARCH DESIGN AND METHODS Glucose homeostasis and β-cell death and proliferation were assessed in Pax4- or Pax4R129 W-overexpressing transgenic animals challenged with or without streptozotocin. Isolated transgenic islets were also exposed to cytokines, and apoptosis was evaluated by DNA fragmentation or cytochrome C release. The expression profiles of proliferation and apoptotic genes and β-cell markers were studied by immunohistochemistry and quantitative RT-PCR. RESULTS Pax4 but not Pax4R129 W protected animals against streptozotocin-induced hyperglycemia and isolated islets from cytokine-mediated β-cell apoptosis. Cytochrome C release was abrogated in Pax4 islets treated with cytokines. Interleukin-1β transcript levels were suppressed in Pax4 islets, whereas they were increased along with NOS2 in Pax4R129 W islets. Bcl-2, Cdk4, and c-myc expression levels were increased in Pax4 islets while MafA, insulin, and GLUT2 transcript levels were suppressed in both animal models. Long-term Pax4 expression promoted proliferation of a Pdx1-positive cell subpopulation while impeding insulin secretion. Suppression of Pax4 rescued this defect with a concomitant increase in pancreatic insulin content. CONCLUSIONS Pax4 protects adult islets from stress-induced apoptosis by suppressing selective nuclear factor-κB target genes while increasing Bcl-2 levels. Furthermore, it promotes dedifferentiation and proliferation of β-cells through MafA repression, with a concomitant increase in Cdk4 and c-myc expression.
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Rationale: Experimental autoimmune myocarditis (EAM) mirrors important pathogenic aspects of inflammatory cardiomyopathy, a common cause of heart failure. In EAM, TGF-β-dependent conversion of heart-infiltrating prominin-1+ progenitors into myofibroblasts is critical for development of fibrosis and the end-stage heart failure phenotype. Therapeutic strategies modulating the in vivo fate of prominin-1+ progenitors might therefore prevent TGF-β-mediated cardiac fibrosis and pathological remodelling. Methods and Results: EAM was induced in BALB/c mice using alpha-myosin heavy chain (aMyHC) peptide/complete Freund's adjuvant (CFA) immunization. Prominin-1+ cells were isolated from the inflamed hearts at day 21 after immunization, expanded and treated with Macrophage Colony-Stimulating Factor (M-CSF) or Transforming Growth Factor-beta (TGF-β). Herein, we demonstrated that M-CSF turns, ex vivo and in the EAM, heart-infiltrating prominin-1+ progenitors into immunosuppressive F4/80/CD11b/CD16/32/NOS2-expressing, nitric oxide producing and E.coli bacteria phygocyting macrophages, and protect further TGF-β-stimulated differentiation into pathogenic myofibroblasts. Systemic M-CSF treatment during myocarditis completely prevented post-inflammatory fibrosis, T cell relapse and left ventricular dysfunction. Mechanistically, M-CSF-induced macrophage differentiation from prominin-1+ progenitors critically required nitric oxide synthase 2. Accordingly, M-CSF treatment failed to reduce myocardial fibrosis development in Nos2-/- mice. Conclusions: Altering the in vivo fate of inflammatory prominin-1 expressing progenitors from pro-fibrotic into the F4/80 expressing macrophage phenotype protects from myocarditis progression, cardiac fibrosis, and heart failure. These findings offer a modern therapeutic model and challenge former concepts, which attributed macrophages a detrimental role in inflammatory cardiomyopathy progression.
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OBJECTIVE: Blood-sucking arthropods' salivary glands contain a remarkable diversity of antihemostatics. The aim of the present study was to identify the unique salivary anticoagulant of the sand fly Lutzomyia longipalpis, which remained elusive for decades. METHODS AND RESULTS: Several L. longipalpis salivary proteins were expressed in human embryonic kidney 293 cells and screened for inhibition of blood coagulation. A novel 32.4-kDa molecule, named Lufaxin, was identified as a slow, tight, noncompetitive, and reversible inhibitor of factor Xa (FXa). Notably, Lufaxin's primary sequence does not share similarity to any physiological or salivary inhibitors of coagulation reported to date. Lufaxin is specific for FXa and does not interact with FX, Dansyl-Glu-Gly-Arg-FXa, or 15 other enzymes. In addition, Lufaxin blocks prothrombinase and increases both prothrombin time and activated partial thromboplastin time. Surface plasmon resonance experiments revealed that FXa binds Lufaxin with an equilibrium constant ≈3 nM, and isothermal titration calorimetry determined a stoichiometry of 1:1. Lufaxin also prevents protease-activated receptor 2 activation by FXa in the MDA-MB-231 cell line and abrogates edema formation triggered by injection of FXa in the paw of mice. Moreover, Lufaxin prevents FeCl(3)-induced carotid artery thrombus formation and prolongs activated partial thromboplastin time ex vivo, implying that it works as an anticoagulant in vivo. Finally, salivary gland of sand flies was found to inhibit FXa and to interact with the enzyme. CONCLUSIONS: Lufaxin belongs to a novel family of slow-tight FXa inhibitors, which display antithrombotic and anti-inflammatory activities. It is a useful tool to understand FXa structural features and its role in prohemostatic and proinflammatory events.
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In the pathogenesis of type I diabetes mellitus, activated leukocytes infiltrate pancreatic islets and induce beta cell dysfunction and destruction. Interferon (IFN)-gamma, tumor necrosis factor-alpha and interleukin (IL)-1 beta play important, although not completely defined, roles in these mechanisms. Here, using the highly differentiated beta Tc-Tet insulin-secreting cell line, we showed that IFN-gamma dose- and time-dependently suppressed insulin synthesis and glucose-stimulated secretion. As described previously IFN-gamma, in combination with IL-1 beta, also induces inducible NO synthase expression and apoptosis (Dupraz, P., Cottet, S., Hamburger, F., Dolci, W., Felley-Bosco, E., and Thorens, B. (2000) J. Biol. Chem. 275, 37672--37678). To assess the role of the Janus kinase/signal transducer and activator of transcription (STAT) pathway in IFN-gamma intracellular signaling, we stably overexpressed SOCS-1 (suppressor of cytokine signaling-1) in the beta cell line. We demonstrated that SOCS-1 suppressed cytokine-induced STAT-1 phosphorylation and increased cellular accumulation. This was accompanied by a suppression of the effect of IFN-gamma on: (i) reduction in insulin promoter-luciferase reporter gene transcription, (ii) decrease in insulin mRNA and peptide content, and (iii) suppression of glucose-stimulated insulin secretion. Furthermore, SOCS-1 also suppressed the cellular effects that require the combined presence of IL-1 beta and IFN-gamma: induction of nitric oxide production and apoptosis. Together our data demonstrate that IFN-gamma is responsible for the cytokine-induced defect in insulin gene expression and secretion and that this effect can be completely blocked by constitutive inhibition of the Janus kinase/STAT pathway.
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Bone loss secondary to inflammatory bowel diseases (IBD) is largely explained by activated T cells producing cytokines that trigger osteoclastogenesis and accelerate bone resorptionwhile inhibiting bone formation. In IBD, elevated expression of interleukin (IL)-15, a T cell growth factor, plays a central role in T cell activation, pro-inflammatory cytokine production and the development of colitis. We previously reported that IL-15 enhances RANKL-induced osteoclastogenesis and that an IL-15 antagonist, CRB-15, prevents weight and bone loss in a mousemodel of dextran sulfate sodium-induced colitis.We hypothesized that inhibition of IL-15 signalingmight prevent bone loss in IL-10 deficient (IL10−/−) mice, that develop spontaneous bowel inflammation associatedwith osteopeniawhen they are no longer raised under germ-free conditions.Mice received anIL-15 antagonist (CRB-15, 5 μg/day, n=5) or IgG2a (5 μg/day, n=4) fromweek 10 to 14 of age. The severity of colitis was assessed by histology and bowel cytokine gene expression by real time PCR. Bone mass and architecturewere evaluated by ex vivo DXA on femur and micro-computed tomography on femur and vertebra. Bodyweight gainwas similar in the two groups. After 4 weeks, colonwas 29% shorter in CRB-15 treatedmice (p<0.006), a sign of reduced inflammation. Histological analysis indicated a transmural infiltration of inflammatory cells, lymphoepithelial lesions and increased size of villi (histological score=4/6) in IgG2a treated mice, whereas colon from CRB-15 treated mice exhibited mild infiltration of inflammatory cells of the lamina propria, no mucosal damages and a minimal increased size of villi (histological score=1.6/6). Levels of TNFα, IL-17 and IL-6 mRNA in the colon were significantly reduced in CRB-15 treated mice (p<0.04 vs IgG2), indicating a decrease in colon inflammation. CRB-15 improved femur BMD (+10.6% vs IgG2a, p<0.002), vertebral trabecular bone volume fraction (BV/TV, +19.7% vs IgG2a, p<0.05) and thickness (+11.6% vs IgG2a, p<0.02). A modest but not significant increase in trabecular BV/TV was observed at the distal femur. Cortical thicknesswas also higher at themidshaft femur in CRB-15 treatedmice (+8.3% vs IgG2a, p<0.02). In conclusion, we confirm and extend our results about the effects of CRB-15 in colitis. Antagonizing IL-15 may exert favorable effects on intestinal inflammation and prevent bone loss and microarchitecture alterations induced by colitis. This article is part of a Special Issue entitled ECTS 2011. Disclosure of interest: B. Brounais-Le Royer Grant / Research Support from Novartis Consumer Health Foundation, S. Ferrari-Lacraz: none declared, D. Velin: none declared, X. Zheng: none declared, S. Ferrari: none declared, D. Pierroz: none declared.
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In this study, we evaluated whether human serum and lipoproteins, especially high-density lipoprotein (HDL), affected serum amyloid A (SAA)-induced cytokine release. We verified the effects of SAA on THP-1 cells in serum-free medium compared to medium containing human serum or lipoprotein-deficient serum. SAA-induced tumour necrosis factor-alpha (TNF-α) production was higher in the medium containing lipoprotein-deficient serum than in the medium containing normal human serum. The addition of HDL inhibited the SAA-induced TNF-α release in a dose-dependent manner. This inhibitory effect was specific for HDL and was not affected by low-density lipoprotein or very low-density lipoprotein. In human peripheral blood mononuclear cells, the inhibitory effect of HDL on TNF-α production induced by SAA was less pronounced. However, this effect was significant when HDL was added to lipoprotein-deficient medium. In addition, a similar inhibitory effect was observed for interleukin-1 beta release. These findings confirm the important role of HDL and support our previous hypothesis that HDL inhibits the effects of SAA during SAA transport in the bloodstream. Moreover, the HDL-induced reduction in the proinflammatory activity of SAA emphasizes the involvement of SAA in diseases, such as atherosclerosis, that are characterized by low levels of HDL.
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Background and objectives Interleukin 18 (IL-18) is a pleiotropic cytokine involved in rheumatoid arthritis (RA) pathogenesis. This study was carried out to evaluate the effi cacy of IL-18 binding protein (IL-18BP) gene therapy in the rat adjuvant- induced arthritis (AIA) model and to decipher the mechanisms by which IL-18BP delivery lessens bone destruction.Materials and methods Arthritis was induced in female Lewis rat by Mycobacterium butyricum and the mRNA expression of IL-18 and IL-18BP was determined in the joints. In a preventive study, rats were divided into an adenovirus producing IL-18BP-Fc (AdmIL-18BP-Fc) group (n=8) and an adenovirus producing green fl uorescent protein (AdGFP) group (n=7). On day 8 after AIA induction, adenoviruses were injected. Clinical parameters were assessed. At day 18, during maximal arthritis, the rats were euthanized, ankles were collected and x-rays were performed. mRNA and protein were extracted from joints for analysis by quantitative reverse transcriptase-PCR, multiplex, Western blot and zymography.Results The authors observed a decrease in the (IL-18BP/ IL-18) ratio from day 7 to 45. Administration of AdmIL-18BPd-Fc decreased clinical parameters and prevented bone and joint destruction compared to AdGFP administration. IL-18BP delivery reduced the (receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG)) ratio by 70%, the matrix metalloproteinase 9 (MMP9) level by 33% and the tartrate-resistant acid phosphatase (TRAP) level by 44% in the joint homogenates from AdmIL-18BPd-Fc compared to AdGFP treated rats.Conclusions In rat AIA, a decrease in the (IL-18BP/IL-18) ratio was observed. IL-18BP delivery prevented joint and bone destruction by downregulating MMP9, (RANKL/OPG) and TRAP, suggesting a potential benefi t of a similar therapy in RA.Abstract topics Towards novel therapeutic strategies.
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Efficient initiation by the DNA polymerase of adenovirus type 2 requires nuclear factor I (NFI), a cellular sequence-specific transcription factor. Three functions of NFI--dimerization, DNA binding, and activation of DNA replication--are colocalized within the N-terminal portion of the protein. To define more precisely the role of NFI in viral DNA replication, a series of site-directed mutations within the N-terminal domain have been generated, thus allowing the separation of all three functions contained within this region. Impairment of the dimerization function prevents sequence-specific DNA binding and in turn abolishes the NFI-mediated activation of DNA replication. NFI DNA-binding activity, although necessary, is not sufficient to activate the initiation of adenovirus replication. A distinct class of NFI mutations that abolish the recruitment of the viral DNA polymerase to the origin also prevent the activation of replication. Thus, a direct interaction of NFI with the viral DNA polymerase complex is required to form a stable and active preinitiation complex on the origin and is responsible for the activation of replication by NFI.
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Activation of the transcription factor PPARγ by the n-3 fatty acid docosahexaenoic acid (DHA) is implicated in controlling proinflammatory cytokine secretion, but the intracellular signaling pathways engaged by PPARγ are incompletely characterized. Here, we identify the adapter-encoding gene SOCS3 as a critical transcriptional target of PPARγ. SOCS3 promoter binding and gene transactivation by PPARγ was associated with a repression in differentiation of proinflammatory T-helper (TH)17 cells. Accordingly, TH17 cells induced in vitro displayed increased SOCS3 expression and diminished capacity to produce interleukin (IL)-17 following activation of PPARγ by DHA. Furthermore, naïve CD4 T cells derived from mice fed a DHA-enriched diet displayed less capability to differentiate into TH17 cells. In two different mouse models of cancer, DHA prevented tumor outgrowth and angiogenesis in an IL-17-dependent manner. Altogether, our results uncover a novel molecular pathway by which PPARγ-induced SOCS3 expression prevents IL-17-mediated cancer growth. Cancer Res; 73(12); 3578-90. ©2013 AACR.
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OBJECTIVE: Chronic activation of the nuclear factor-kappaB (NF-kappaB) in white adipose tissue leads to increased production of pro-inflammatory cytokines, which are involved in the development of insulin resistance. It is presently unknown whether peroxisome proliferator-activated receptor (PPAR) beta/delta activation prevents inflammation in adipocytes. RESEARCH DESIGN AND METHODS AND RESULTS: First, we examined whether the PPARbeta/delta agonist GW501516 prevents lipopolysaccharide (LPS)-induced cytokine production in differentiated 3T3-L1 adipocytes. Treatment with GW501516 blocked LPS-induced IL-6 expression and secretion by adipocytes and the subsequent activation of the signal transducer and activator of transcription 3 (STAT3)-Suppressor of cytokine signaling 3 (SOCS3) pathway. This effect was associated with the capacity of GW501516 to impede LPS-induced NF-kappaB activation. Second, in in vivo studies, white adipose tissue from Zucker diabetic fatty (ZDF) rats, compared with that of lean rats, showed reduced PPARbeta/delta expression and PPAR DNA-binding activity, which was accompanied by enhanced IL-6 expression and NF-kappaB DNA-binding activity. Furthermore, IL-6 expression and NF-kappaB DNA-binding activity was higher in white adipose tissue from PPARbeta/delta-null mice than in wild-type mice. Because mitogen-activated protein kinase-extracellular signal-related kinase (ERK)1/2 (MEK1/2) is involved in LPS-induced NF-kappaB activation in adipocytes, we explored whether PPARbeta/delta prevented NF-kappaB activation by inhibiting this pathway. Interestingly, GW501516 prevented ERK1/2 phosphorylation by LPS. Furthermore, white adipose tissue from animal showing constitutively increased NF-kappaB activity, such as ZDF rats and PPARbeta/delta-null mice, also showed enhanced phospho-ERK1/2 levels. CONCLUSIONS: These findings indicate that activation of PPARbeta/delta inhibits enhanced cytokine production in adipocytes by preventing NF-kappaB activation via ERK1/2, an effect that may help prevent insulin resistance.
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Chronic renal failure (CRF) is associated with the development of secondary hyperparathyroidism and vascular calcifications. We evaluated the efficacy of PA21, a new iron-based noncalcium phosphate binder, in controlling phosphocalcic disorders and preventing vascular calcifications in uremic rats. Rats with adenine-diet-induced CRF were randomized to receive either PA21 0.5, 1.5, or 5% or CaCO3 3% in the diet for 4 weeks, and were compared with uremic and nonuremic control groups. After 4 weeks of phosphate binder treatment, serum calcium, creatinine, and body weight were similar between all CRF groups. Serum phosphorus was reduced with CaCO3 3% (2.06 mM; P ≤ 0.001), PA21 1.5% (2.29 mM; P < 0.05), and PA21 5% (2.21 mM; P ≤ 0.001) versus CRF controls (2.91 mM). Intact parathyroid hormone was strongly reduced in the PA21 5% and CaCO3 3% CRF groups to a similar extent (1138 and 1299 pg/ml, respectively) versus CRF controls (3261 pg/ml; both P ≤ 0.001). A lower serum fibroblast growth factor 23 concentration was observed in the PA21 5%, compared with CaCO3 3% and CRF, control groups. PA21 5% CRF rats had a lower vascular calcification score compared with CaCO3 3% CRF rats and CRF controls. In conclusion, PA21 was as effective as CaCO3 at controlling phosphocalcic disorders but superior in preventing the development of vascular calcifications in uremic rats. Thus, PA21 represents a possible alternative to calcium-based phosphate binders in CRF patients.
The cyclophilin inhibitor alisporivir prevents hepatitis C virus-mediated mitochondrial dysfunction.
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Alisporivir (Debio-025) is an analogue of cyclosporine A and represents the prototype of a new class of non-immunosuppressive cyclophilin inhibitors. In vitro and in vivo studies have shown that alisporivir inhibits hepatitis C virus (HCV) replication, and ongoing clinical trials are exploring its therapeutic potential in patients with chronic hepatitis C. Recent data suggest that the antiviral effect is mediated by inhibition of cyclophilin A, which is an essential host factor in the HCV life cycle. However, alisporivir also inhibits mitochondrial permeability transition by binding to cyclophilin D. Because HCV is known to affect mitochondrial function, we explored the effect of alisporivir on HCV protein-mediated mitochondrial dysfunction. Through the use of inducible cell lines, which allow to investigate the effects of HCV polyprotein expression independent from viral RNA replication and which recapitulate the major alterations of mitochondrial bioenergetics observed in infectious cell systems, we show that alisporivir prevents HCV protein-mediated decrease of cell respiration, collapse of mitochondrial membrane potential, overproduction of reactive oxygen species and mitochondrial calcium overload. Strikingly, some of the HCV-mediated mitochondrial dysfunctions could even be rescued by alisporivir. Conclusion: These observations provide new insights into the pathogenesis of HCV-related liver disease and reveal an additional mechanism of action of alisporivir that is likely beneficial in the treatment of chronic hepatitis C. (HEPATOLOGY 2012).
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The pro-inflammatory cytokine IL-1β has been shown to promote angiogenesis. It can have a neurotoxic or neuroprotective effect. Here, we have studied the expression of IL-1β in vivo and the effect of the IL-1 receptor antagonist on choroidal neovascularization (CNV) and retinal degeneration (RD). IL-1β expression significantly increased after laser injury (real time PCR) in C57BL/6 mice, in the C57BL/6 Cx3cr1(-/-) model of age-related macular degeneration (enzyme-linked immunoabsorbent assay), and in albino Wistar rats and albino BALB Cx3cr1(+/+) and Cx3cr1(-/-) mice (enzyme-linked immunoabsorbent assay) after light injury. IL-1β was localized to Ly6G-positive, Iba1-negative infiltrating neutrophils in laser-induced CNV as determined by IHC. IL-1 receptor antagonist treatment significantly inhibited CNV but did not affect Iba1-positive macrophage recruitment to the injury site. IL-1β significantly increased endothelial cell outgrowth in aortic ring assay independently of vascular endothelial growth factor, suggesting a direct effect of IL-1β on choroidal endothelial cell proliferation. Inhibition of IL-1β in light- and laser-induced RD models did not alter photoreceptor degeneration in Wistar rats, C57BL/6 mice, or RD-prone Cx3cr1(-/-) mice. Our results suggest that IL-1β inhibition might represent a valuable and safe alternative to inhibition of vascular endothelial growth factor in the control of CNV in the context of concomitant photoreceptor degeneration as observed in age-related macular degeneration.