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252
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Mikuni S, Tamura M, Kinjo M. Analysis of intranuclear binding process of glucocorticoid receptor using fluorescence correlation spectroscopy. FEBS Lett 2007; 581:389-93. [PMID: 17239375 DOI: 10.1016/j.febslet.2006.12.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 12/08/2006] [Accepted: 12/21/2006] [Indexed: 11/17/2022]
Abstract
The diffusion properties of EGFP-hGRalpha and mutants C421G, A458T and I566 in living cells were analyzed. The wild type and mutants C421G and A458T translocated from the cytoplasm to the nucleus after addition of Dex; however, the Brownian motions of the proteins were different. The diffusion constant of wild-type GRalpha after addition of Dex slowed to 15.6% of that in the absence of Dex, whereas those of A458T and C421G slowed to 34.8% and 61.7%, respectively. This is the first report that dimer formation is less important than the binding activity of GRalpha to GRE in the living cell.
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Affiliation(s)
- Shintaro Mikuni
- Laboratory of Supramolecular Biophysics, Research Institute for Electronic Science, Hokkaido University, N12W6, Kita-ku, Sapporo 060-0812, Japan
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253
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Bros M, Jährling F, Renzing A, Wiechmann N, Dang NA, Sutter A, Ross R, Knop J, Sudowe S, Reske-Kunz AB. A newly established murine immature dendritic cell line can be differentiated into a mature state, but exerts tolerogenic function upon maturation in the presence of glucocorticoid. Blood 2007; 109:3820-9. [PMID: 17209058 DOI: 10.1182/blood-2006-07-035576] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Abstract
The phenotype and function of murine dendritic cells (DCs) are primarily studied using bone-marrow–derived DCs (BM-DCs), but may be hampered by the heterogenous phenotype of BM-DCs due to their differential state of maturation. Here we characterize a newly established murine DC line (SP37A3) of myeloid origin. During maintainance in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and M-CSF, SP37A3 cells resemble immature DCs characterized by low expression of major histocompatibility complex (MHC) II and costimulatory molecules and low T-cell stimulatory capacity. Upon stimulation, SP37A3 cells acquire a mature phenotype and activate naive T cells as potently as BM-DCs. Similar to BM-DCs, SP37A3 cells activated in the presence of dexamethasone-induced regulatory T cells, which were anergic upon restimulation and suppressed proliferation of naive T cells. This tolerogenic state was reflected by lower expression levels of costimulatory molecules and proinflammatory cytokines compared with mature cells, as well as up-regulated expression of FcγRIIB and interleukin-1RA (IL-1RA). SP37A3 cells were responsive to dexamethasone even when applied at later time points during activation, suggesting functional plasticity. Thus, DC line SP37A3 represents a suitable model to study functions of immature and mature as well as tolerogenic myeloid DCs, circumventing restrictions associated with the use of primary DCs and BM-DCs.
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Affiliation(s)
- Matthias Bros
- Clinical Research Unit Allergology, Department of Dermatology, Johannes Gutenberg-University, Obere Zahlbacher Strasse 63, D-55131 Mainz, Germany
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254
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Pace TWW, Hu F, Miller AH. Cytokine-effects on glucocorticoid receptor function: relevance to glucocorticoid resistance and the pathophysiology and treatment of major depression. Brain Behav Immun 2007; 21:9-19. [PMID: 17070667 PMCID: PMC1820632 DOI: 10.1016/j.bbi.2006.08.009] [Citation(s) in RCA: 426] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/18/2006] [Accepted: 08/25/2006] [Indexed: 12/22/2022] Open
Abstract
Glucocorticoids play an essential role in the response to environmental stressors, serving initially to mobilize bodily responses to challenge and ultimately serving to restrain neuroendocrine and immune reactions. A number of diseases including autoimmune, infectious and inflammatory disorders as well as certain neuropsychiatric disorders such as major depression have been associated with decreased responsiveness to glucocorticoids (glucocorticoid resistance), which is believed to be related in part to impaired functioning of the glucocorticoid receptor (GR). Glucocorticoid resistance, in turn, may contribute to excessive inflammation as well as hyperactivity of corticotropin releasing hormone and sympathetic nervous system pathways, which are known to contribute to a variety of diseases as well as behavioral alterations. Recent data indicate that glucocorticoid resistance may be a result of impaired GR function secondary to chronic exposure to inflammatory cytokines as may occur during chronic medical illness or chronic stress. Indeed, inflammatory cytokines and their signaling pathways including mitogen-activated protein kinases, nuclear factor-kappaB, signal transducers and activators of transcription, and cyclooxygenase have been found to inhibit GR function. Mechanisms include disruption of GR translocation and/or GR-DNA binding through protein-protein interactions of inflammatory mediators with the GR itself or relevant steroid receptor cofactors as well as alterations in GR phosphorylation status. Interestingly, cAMP signal transduction pathways can enhance GR function and inhibit cytokine signaling. Certain antidepressants have similar effects. Thus, further understanding the effects of cytokines on GR signaling and the mechanisms involved may reveal novel therapeutic targets for reversal of glucocorticoid resistance and restoration of glucocorticoid-mediated inhibition of relevant bodily/immune responses during stress and immune challenge.
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Affiliation(s)
- Thaddeus W W Pace
- Department of Psychiatry and Behavioral Sciences, Winship Cancer Institute, Emory University School of Medicine, 101 Woodruff Cricle, Suite 4000, Atlanta, GA 30322, USA
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255
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Mikuni S, Pack C, Tamura M, Kinjo M. Diffusion analysis of glucocorticoid receptor and antagonist effect in living cell nucleus. Exp Mol Pathol 2006; 82:163-8. [PMID: 17274977 DOI: 10.1016/j.yexmp.2006.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 12/02/2006] [Indexed: 10/23/2022]
Abstract
The diffusion properties of hGRalpha in living cells have been analyzed. The hGRalpha translocalized from the cytosol to the nucleus after addition of Dex just as RU486; however, the Brownian motions of the proteins in nucleus were different. In order to analysis microenvironment of the nucleus of living cell, four different tandem EGFPs were constructed. Diffusion of tandem EGFP was dependent on the length of the protein as a rod-like molecule in solution. We found two kinds of mobility, fast diffusional mobility as a major component and much slower diffusional mobility as a major component in living cells nucleoplasm. On the bases of this analysis, we compared the diffusion property of hGRalpha in the nucleus at the presence of Dex or RU486 by distribution of diffusion constants. Our result may suggest that EGFP-hGRalpha is activated by RU486 and kept the stage of binding cofactor, GRE and final complex. Finally this means that dimerization is not required for association with GRE, although it is required for stabilization of a complex of EGFP-hGRalpha.
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Affiliation(s)
- Shintaro Mikuni
- Laboratory of Supramolecular Biophysics, Research Institute for Electronic Science, Hokkaido University, N12W6, Sapporo 060-0812, Japan
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256
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Donn R, Berry A, Stevens A, Farrow S, Betts J, Stevens R, Clayton C, Wang J, Warnock L, Worthington J, Scott L, Graham S, Ray D. Use of gene expression profiling to identify a novel glucocorticoid sensitivity determining gene, BMPRII. FASEB J 2006; 21:402-14. [PMID: 17185747 DOI: 10.1096/fj.06-7236com] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Wide variation in glucocorticoid (Gc) sensitivity exists between individuals which may influence susceptibility to, and treatment response of, inflammatory diseases. To determine a genetic fingerprint of Gc sensitivity 100 healthy human volunteers were polarized into the 10% most Gc-sensitive and 10% most Gc-resistant following a low dose dexamethasone (0.25 mg) suppression test. Gene expression profiling of primary lymphocytes identified the 98 most significantly Gc regulated genes. These genes were used to build a subnetwork of Gc signaling, with 54 genes mapping as nodes, and 6 non-Gc regulated genes inferred as signaling nodes. Twenty four of the 98 genes showed a difference in Gc response in vitro dependent on the Gc sensitivity of their donor individuals in vivo. A predictive model was built using both partial least squares discriminate analysis and support vector machines that predicted donor glucocorticoid sensitivity with 87% accuracy. Discriminating genes included bone morphogenetic protein receptor, type II (BMPRII). Transfection studies showed that BMPRII modulated Gc action. These studies reveal a broad base of gene expression that predicts Gc sensitivity and determine a Gc signaling network in human primary T lymphocytes. Furthermore, this combined gene profiling, and functional analysis approach has identified BMPRII as a modulator of Gc signaling.
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Affiliation(s)
- Rachelle Donn
- Centre for Molecular Medicine, University of Manchester, Oxford Rd., Manchester, M13 9PT, UK
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257
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Maier A, Zimmermann C, Beglinger C, Drewe J, Gutmann H. Effects of budesonide on P-glycoprotein expression in intestinal cell lines. Br J Pharmacol 2006; 150:361-8. [PMID: 17179942 PMCID: PMC2013900 DOI: 10.1038/sj.bjp.0706992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND AND PURPOSE P-glycoprotein (P-gp) is an important efflux transporter that supports the barrier function of the gut against invading antigens and against administered drugs. Since glucocorticoids, such as budesonide, are frequently used during inflammatory bowel disease we investigated how budesonide influences P-gp expression in different intestinal cell lines. EXPERIMENTAL APPROACH LS180 and Caco-2 cells were incubated with budesonide and changes in P-gp expression were determined on mRNA, protein and functional level. The mRNA expression levels of glucocorticoid receptor (GR) and pregnane X receptor (PXR) were determined in these cell lines. PXR receptor was transiently transfected into Caco-2 cells. KEY RESULTS Budesonide showed an induction of P-gp in LS180 cells and a down-regulation in Caco-2 cells. Expression levels of nuclear receptors revealed high expression of PXR only in LS180 cells and exclusive expression of GR in Caco-2 cells. Mifepristone, an anti-glucocorticoid, could not reverse the down-regulation of P-gp by budesonide in Caco-2 cells. In PXR-transfected Caco-2 cells the budesonide-mediated down-regulation of P-gp was abolished. Furthermore the expression of cytochrome P450 3A4 (CYP3A4), another PXR target gene, was induced in PXR-transfected Caco-2 cells after budesonide treatment. CONCLUSIONS AND IMPLICATIONS Budesonide has the potential to influence MDR1 expression in vitro. In LS180 cells, the induction of MDR1 by budesonide probably is mediated via PXR. The mechanism of the down-regulation in Caco-2 cells still remains unclear, but GR does not seem to be involved. Further studies are required to evaluate how budesonide alters P-gp expression in vivo.
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Affiliation(s)
- A Maier
- Department of Clinical Pharmacology and Toxicology, University Hospital Basel Basel, Switzerland
| | - C Zimmermann
- Department of Clinical Pharmacology and Toxicology, University Hospital Basel Basel, Switzerland
| | - C Beglinger
- Department of Internal Medicine, Division of Gastroenterology, University Hospital of Basel Basel, Switzerland
| | - J Drewe
- Department of Clinical Pharmacology and Toxicology, University Hospital Basel Basel, Switzerland
- Author for correspondence:
| | - H Gutmann
- Department of Clinical Pharmacology and Toxicology, University Hospital Basel Basel, Switzerland
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258
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Izumo M, Sato TR, Straume M, Johnson CH. Quantitative analyses of circadian gene expression in mammalian cell cultures. PLoS Comput Biol 2006; 2:e136. [PMID: 17040123 PMCID: PMC1599765 DOI: 10.1371/journal.pcbi.0020136] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 08/28/2006] [Indexed: 01/17/2023] Open
Abstract
The central circadian pacemaker is located in the hypothalamus of mammals, but essentially the same oscillating system operates in peripheral tissues and even in immortalized cell lines. Using luciferase reporters that allow automated monitoring of circadian gene expression in mammalian fibroblasts, we report the collection and analysis of precise rhythmic data from these cells. We use these methods to analyze signaling pathways of peripheral tissues by studying the responses of Rat-1 fibroblasts to ten different compounds. To quantify these rhythms, which show significant variation and large non-stationarities (damping and baseline drifting), we developed a new fast Fourier transform–nonlinear least squares analysis procedure that specifically optimizes the quantification of amplitude for circadian rhythm data. This enhanced analysis method successfully distinguishes among the ten signaling compounds for their rhythm-inducing properties. We pursued detailed analyses of the responses to two of these compounds that induced the highest amplitude rhythms in fibroblasts, forskolin (an activator of adenylyl cyclase), and dexamethasone (an agonist of glucocorticoid receptors). Our quantitative analyses clearly indicate that the synchronization mechanisms by the cAMP and glucocorticoid pathways are different, implying that actions of different genes stimulated by these pathways lead to distinctive programs of circadian synchronization. The circadian biological clock controls the adaptation of animals and plants to the daily environmental cycle of light and darkness. As such, this clock is responsible for jet lag and has consequences for mental health (e.g., depression), physical health (e.g., athletic performance and the timing of heart attacks), and social issues (e.g., shift work). The central circadian pacemaker is located in the hypothalamus of the mammalian brain, but essentially the same oscillating system operates in nonneural tissues. Using luciferase, an enzyme that emits light, the authors could monitor circadian gene expression in mammalian fibroblasts via luminescence emission that is controlled by the biological clock. Using this method, they report the collection and analysis of precise rhythmic data from these cells. These methods were used to analyze signaling pathways by studying the responses of fibroblasts to a variety of different treatments, including drugs, growth factors, and serum. The authors developed a new analysis procedure that specifically optimizes the quantification of amplitude for cyclic data to analyze these rhythms. This enhanced analysis method successfully distinguishes among the various signaling treatments for their rhythm inducing properties. The quantitative analyses clearly indicate that the synchronization mechanisms by the cyclic AMP and glucocorticoid pathways are different. Therefore, these pathways lead to distinctive programs of circadian synchronization.
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Affiliation(s)
- Mariko Izumo
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Takashi R Sato
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Martin Straume
- Customized Online Biomathematical Research Applications, Charlottesville, Virginia, United States of America
| | - Carl Hirschie Johnson
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- * To whom correspondence should be addressed. E-mail:
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259
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De Bosscher K, Vanden Berghe W, Haegeman G. Cross-talk between nuclear receptors and nuclear factor kappaB. Oncogene 2006; 25:6868-86. [PMID: 17072333 DOI: 10.1038/sj.onc.1209935] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A variety of studies have shown that some activated nuclear receptors (NRs), especially the glucorticoid receptor, the estrogen receptor and peroxisome proliferator-activated receptor, can inhibit the activity of the transcription factor nuclear factor kappaB (NF-kappaB), which plays a key role in the control of genes involved in inflammation, cell proliferation and apoptosis. This review describes the molecular mechanisms of cross-talk between NRs and NF-kappaB and the biological relevance of this cross-talk. The importance and mechanistic aspects of selective NR modulation are discussed. Also included are future research prospects, which will lead to a new era in the field of NR research with the aim of specifically inhibiting NF-kappaB-driven gene expression for anti-inflammatory, anti-tumor and immune-modulatory purposes.
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Affiliation(s)
- K De Bosscher
- Laboratory for Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Molecular Biology, Ghent University, Gent, Belgium.
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260
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Duma D, Jewell CM, Cidlowski JA. Multiple glucocorticoid receptor isoforms and mechanisms of post-translational modification. J Steroid Biochem Mol Biol 2006; 102:11-21. [PMID: 17070034 DOI: 10.1016/j.jsbmb.2006.09.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Glucocorticoids regulate diverse physiological effects in virtually every organ and tissue in the body. Glucocorticoid actions are mediated through the glucocorticoid receptor (GR), a ligand-dependent transcriptional factor that activates or represses gene transcription. Since, the cloning of the human GR in 1985, research efforts have been focused on describing the mechanism of action exerted by one of the GR isoforms, GRalpha. However, recent studies from our lab and others have suggested that multiple isoforms of hGR are generated from one single gene and one mRNA species by the mechanisms of alternative RNA splicing and alternative translation initiation. These isoforms display diverse cytoplasm-to-nucleus trafficking patterns and distinct transcription activities. In addition, this new information predicts that each hGR protein can be subjected to a variety of post-translational modifications, such as phosphorylation, sumoylation and ubiquitination. The nature and degree of post-translational modification, as well as subcellular localization, may differentially modulate stability and function among the GR isoforms in different tissues providing an additional important mechanism for regulation of GR action. We outline the recent advances made in identifying the processes that generate and modify multiple GR isoforms and the post-translational modifications that contribute to the increasing diversity in the glucocorticoid signaling pathway.
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Affiliation(s)
- Danielle Duma
- Laboratory of Signal Transduction, Molecular Endocrinology Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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261
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Psarra AMG, Solakidi S, Sekeris CE. The Mitochondrion as a Primary Site of Action of Regulatory Agents Involved in Neuroimmunomodulation. Ann N Y Acad Sci 2006; 1088:12-22. [PMID: 17192553 DOI: 10.1196/annals.1366.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A major system of neuroimmunomodulation is the hypothalamic-pituitary-adrenocortical (HPA) axis, acting through glucocorticoids and their intracellular signaling components, exerting both stimulatory and inhibitory effects on the immune reaction. Glucocorticoids inhibit the production of proinflammatory cytokines by interacting with nuclear transcription factors (nuclear factor [NF]-kappaB, activated protein [AP]-1) and induce the production of several anti-inflammatory cytokines by gene activation. In some cells and/or in extreme stress conditions, apoptosis is evoked. In most processes related to neuroimmunomodulation a prominent role is emerging for mitochondria. These organelles generate more than 90% of the cell's energy requirements through oxidative phosphorylation (OXPHOS), which is regulated by several agents, including steroid and thyroid hormones. These hormones are inducers of nuclear and mitochondrial OXPHOS gene transcription and they exert a primary action not only on nuclear but also on mitochondrial genes by way of cognate receptors. Recently, additional nuclear transcription factors involved in neuroimmunomodulation have been detected in mitochondria (NF-kappaB, AP-1, p53, calcium/cAMP response element binding protein [CREB]), and binding sites of these and putative binding sites of other nuclear transcription factors have been identified in the mitochondrial genome. The interaction of these factors with mitochondrial regulatory proteins, with receptors and with the genome has been shown and, in some cases, modulation of mitochondrial transcription was observed with possible effects on energy yield. The mitochondria store a host of critical apoptotic activators and inhibitors in their intermembrane space and the release of these factors could be another possible mode of action of the mitochondrially translocated regulatory agents and receptors.
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Affiliation(s)
- A M G Psarra
- Foundation for Biomedical Research of the Academy of Greece, Athens, Greece
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262
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Head CC, Farrow MJ, Sheridan JF, Padgett DA. Androstenediol reduces the anti-inflammatory effects of restraint stress during wound healing. Brain Behav Immun 2006; 20:590-6. [PMID: 16730942 DOI: 10.1016/j.bbi.2006.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Revised: 03/20/2006] [Accepted: 03/22/2006] [Indexed: 10/24/2022] Open
Abstract
Restraint stress (RST) delays wound closure and suppresses pro-inflammatory gene expression by a glucocorticoid-dependent mechanism. Because androstenediol (AED) ameliorates many of the anti-inflammatory influences of glucocorticoids (GC) in vitro, it was hypothesized that treatment of stressed animals with AED would ameliorate the suppressive influence of restraint and restore healing to control levels. To test this hypothesis, male CD1 mice were subjected to nightly cycles of RST beginning 3 days prior to placement of two 3.5 mm full-thickness cutaneous wounds. To assess the influence of AED treatment on wound repair, mice were injected subcutaneously with 2.0 mg of AED or an equivalent volume of delivery vehicle (VEH) prior to wounding. The rate of wound closure was assessed daily by photoplanimetry. In addition, at 3, 6, 12, and 24 h post wounding, IL-1beta, MCP-1, and PDGF RNAs were quantified in wounds as a measure of inflammatory gene expression. The data showed that RST significantly delayed closure as compared to controls. In parallel, RST significantly decreased IL-1beta and PDGF gene expression as early as 12 h after wounding. In contrast, treatment with AED prevented the stress-induced delay in healing. Whereas wounds on VEH/RST mice did not achieve 50% closure until day 7, wounds on AED-treated animals, whether subjected to RST or not, had closed by 50% within 3 days of wounding. In addition, AED treatment prevented the stress-induced suppression of IL-1beta and PDGF gene expression 24 h after injury. Therefore, AED may provide a pharmacologic approach to ameliorate the anti-inflammatory effects of behavioral stress and in doing so, may improve tissue repair.
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Affiliation(s)
- Cynthia C Head
- Section of Oral Biology, College of Dentistry, The Ohio State University, Columbus, OH 43218, USA
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263
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Fernandes PACM, Cecon E, Markus RP, Ferreira ZS. Effect of TNF-alpha on the melatonin synthetic pathway in the rat pineal gland: basis for a 'feedback' of the immune response on circadian timing. J Pineal Res 2006; 41:344-50. [PMID: 17014691 DOI: 10.1111/j.1600-079x.2006.00373.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A retino-hypothalamic-sympathetic pathway drives the nocturnal surge of pineal melatonin production that determines the synchronization of pineal function with the environmental light/dark cycle. In many studies, melatonin has been implicated in the modulation of the inflammatory response. However, scant information on the feedback action of molecules present in the blood on the pineal gland during the time course of an inflammatory response is available. Here we analyzed the effect of tumor necrosis factor-alpha (TNF-alpha) and corticosterone on the transcription of the Aa-nat, hiomt and 14-3-3 protein genes in denervated pineal glands of rats stimulated for 5 hr with norepinephrine, using real-time reverse transcription-polymerase chain reaction. The transcription of Aa-nat, a gene encoding the key enzyme in melatonin biosynthesis, together with the synthesis of the melatonin precursor N-acetylserotonin, was inhibited by TNF-alpha. This inhibition was transient, and a preincubation of TNF-alpha for more than 24 hr had no detectable effect. In fact, a protein(s) transcribed, later on, as shown by cycloheximide, was responsible for the reversal of the inhibition of Aa-nat transcription. In addition, corticosterone induced a potentiation of norepinephrine-induced Aa-nat transcription even after 48 hr of incubation. These data support the hypothesis that the nocturnal surge in melatonin is impaired at the beginning of an inflammatory response and restored either during the shutdown of an acute response or in a chronic inflammatory pathology. Here, we introduce a new molecular pathway involved in the feedback of an inflammatory response on pineal activity, and provide a molecular basis for understanding the expression of circadian timing in injured organisms.
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Affiliation(s)
- Pedro A C M Fernandes
- Laboratory of Chronopharmacology, Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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264
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Herman JP, Seroogy K. Hypothalamic-Pituitary-Adrenal Axis, Glucocorticoids, and Neurologic Disease. Neurol Clin 2006; 24:461-81, vi. [PMID: 16877118 DOI: 10.1016/j.ncl.2006.03.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Neurologic diseases often are accompanied by significant life stress and consequent increases in stress hormone levels. Glucocorticoid stress hormones are known to have deleterious interactions with neurodegenerative processes and are hypersecreted in neurologic disorders and comorbid psychiatric conditions. This review highlights the current state of knowledge of mechanisms controlling activation and inhibition of glucocorticoid secretion, outlines signalling mechanisms used by these hormones in neural tissue, and describes how endogenous glucocorticoids can mitigate neuronal damage in models of neurologic disease. This review highlights the importance of controlling stress and consequent stress hormone secretion in the context of neurologic disease states.
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Affiliation(s)
- James P Herman
- Department of Psychiatry, University of Cincinnati College of Medicine, Cincinnati, OH 45237-0506, USA.
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265
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Canlon B, Meltser I, Johansson P, Tahera Y. Glucocorticoid receptors modulate auditory sensitivity to acoustic trauma. Hear Res 2006; 226:61-9. [PMID: 16843624 DOI: 10.1016/j.heares.2006.05.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 05/18/2006] [Accepted: 05/26/2006] [Indexed: 02/07/2023]
Abstract
Glucocorticoids are widely used to treat different hearing disorders yet the exact mechanisms of glucocorticoid action on the inner ear are not known. The inner ear of both humans and experimental animals demonstrate an abundance of glucocorticoid receptors (GRs) in both neuronal and non-neuronal tissues. In this review, we discuss how activation of the hypothalamic-pituitary-adrenal axis can directly modulate hearing sensitivity. Recent findings indicate that several factors define the responsiveness of the peripheral auditory system to glucocorticoids including the concentration of agonist, availability of the GR, and the activation of GR and NF-kappaB. These findings will further our understanding of individual glucocorticoid responsiveness to steroid treatment, and will help improve the development of pharmaceuticals to selectively target GR in the inner ear for individuals with increased sensitivity to acoustic trauma.
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Affiliation(s)
- Barbara Canlon
- Department of Physiology and Pharmacology, Karolinska Institute, Von Eulers Vag 8, Stockholm 171 77, Sweden.
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266
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Negrini S, Fenoglio D, Balestra P, Fravega M, Filaci G, Indiveri F. Endocrine Regulation of Suppressor Lymphocytes: Role of the Glucocorticoid-Induced TNF-Like Receptor. Ann N Y Acad Sci 2006; 1069:377-85. [PMID: 16855164 DOI: 10.1196/annals.1351.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mechanisms responsible for peripheral immune tolerance are currently under investigation in several laboratories, in order to define the role of immune homeostasis in physiological processes and pathologic conditions, such as autoimmunity and cancer. In this context, recent studies attributed a relevant role to the glucocorticoid-induced TNFR-related gene (GITR). GITR is expressed at high levels on CD4(+)CD25(+). T regulatory (Treg) cells, but only at low levels on resting responder T lymphocytes, and is upregulated after activation. GITR triggering induces both pro- and anti-apoptotic effects through different intracellular pathways, abrogates the suppressive activity of Treg cells, and co-stimulates responder T cells. These data hint that GITR triggering overstimulates the immune system. Indeed, in vivo studies demonstrated that GITR stimulation may both induce autoimmune diseases and strengthen anti-virus and anti-tumor immune responses. Therefore, the GITR-GITRL system appears crucial in regulating immunity. Currently, the majority of studies about GITR's role on regulatory cells are focused on CD4(+)CD25(+) Treg cells, while very little is known about the importance of this molecule in other Treg subtypes. We have recently characterized a subpopulation of CD8+ T suppressor lymphocytes able to inhibit both T cell proliferation and cytotoxicity. Preliminary data show that GITR is expressed on such CD8+ T suppressor cells and that its activation by a specific antibody inhibits generation, but not function, of these cells. These early results suggest the importance of GITR in human T suppressor lymphocytes other than CD4(+)CD25(+) Treg cells.
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Affiliation(s)
- Simone Negrini
- Department of Internal Medicine (DIMI), University of Genoa, Genoa, Italy
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267
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Banciu M, Schiffelers RM, Fens MHAM, Metselaar JM, Storm G. Anti-angiogenic effects of liposomal prednisolone phosphate on B16 melanoma in mice. J Control Release 2006; 113:1-8. [PMID: 16707187 DOI: 10.1016/j.jconrel.2006.03.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 03/28/2006] [Accepted: 03/30/2006] [Indexed: 11/26/2022]
Abstract
Prednisolone phosphate (PLP) encapsulated in long-circulating liposomes can inhibit tumor growth after intravenous administration (i.v.). These antitumor effects of liposomal PLP are the result of the tumor-targeting property of the liposome formulation. The mechanism by which liposomal PLP inhibits tumor growth is unclear. We investigated the effects of liposome-encapsulated PLP versus free PLP on angiogenic protein production in tumor tissue in vivo and on viability and proliferation of tumor and endothelial cells in vitro. In vivo, liposomal PLP had a stronger reducing effect on pro-angiogenic protein levels than free PLP, whereas levels of anti-angiogenic proteins were hardly affected. Cell viability was only slightly affected with either treatment. Liposomal PLP had strong anti-proliferative effects on human umbilical vein endothelial cells, whereas free PLP had hardly any effect. Taken together, the present study points to a strong inhibitory effect of liposomal PLP on tumor angiogenesis by reduction of the intratumoral production of the majority of pro-angiogenic factors studied and direct inhibition of endothelial cell proliferation, which is the result of high prolonged levels of prednisolone in the tumor by liposomal delivery.
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Affiliation(s)
- Manuela Banciu
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Utrecht, The Netherlands
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268
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Novac N, Baus D, Dostert A, Heinzel T. Competition between glucocorticoid receptor and NFκB for control of the human FasL promoter. FASEB J 2006; 20:1074-81. [PMID: 16770006 DOI: 10.1096/fj.05-5457com] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glucocorticoids mediate a variety of biological effects via binding their intracellular receptor. Ligand-bound glucocorticoid receptor (GR) translocates to the nucleus and regulates gene transcription in a DNA binding-dependent or independent manner. The predominant biological effect of glucocorticoids on peripheral T cells is immunosupression via transcriptional repression of genes induced during T cell activation. Glucocorticoids have been implicated in the inhibition of activation-induced T cell apoptosis by virtue of their down-regulation of Fas ligand (fasL) expression. It is believed that FasL, similar to other cytokines, is repressed by glucocorticoids via GR interaction with other transcription factors, interfering with their transactivation ability. Here, we show that human fasL is directly regulated by GR in a DNA binding-dependent manner. A negative GR element found at position -990 in the fasL promoter binds GR in vitro as well as in the chromatin context. This negative glucocorticoid response element overlaps with a known NFkappaB binding site. GR down-regulates fasL promoter by competing with NFkappaB for binding to the common response element. Thus, fasL is the first gene described whose repression by GR is mediated by sterical occlusion of NFkappaB DNA binding. This type of repression represents an additional mechanism for the GR-NFkappaB mutual antagonism.
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Affiliation(s)
- Natalia Novac
- Georg-Speyer-Haus, Institute for Biomedical Research, Frankfurt, Germany
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269
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Okazaki SI, Yamakawa M, Maeda K, Ohta N, Aoyagi M. Expression of glucocorticoid receptors in non-neoplastic lymphoid follicles and B cell type malignant lymphomas. J Clin Pathol 2006; 59:410-6. [PMID: 16461807 PMCID: PMC1860370 DOI: 10.1136/jcp.2005.025858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE To evaluate the expression of human glucocorticoid receptors (hGRs), such as hGR (4H2), hGR-alpha, and hGR-beta, in non-neoplastic lymphoid follicles and B cell type malignant lymphomas. METHODS The expression of hGRs in non-neoplastic lymphoid follicles and malignant lymphomas, including diffuse large cell lymphoma, mantle cell lymphoma, and follicular lymphoma, was examined immunohistochemically. HGR (4H2) expression was confirmed by double immunostaining of tissues and in isolated cells from tonsillar germinal centres, and by immunoelectronmicroscopy. RESULTS In secondary lymphoid follicles of any non-neoplastic diseases--such as chronic tonsillitis, reactive lymphadenitis, and Kimura's disease--the germinal centre cells often expressed hGR (4H2) and hGR-alpha. Double immunocytochemical staining of isolated germinal centre cells showed that the majority of hGR (4H2) positive cells were CD20 positive B cells, and that follicular dendritic cells also expressed hGR. Immunoelectronmicroscopy revealed the presence of nuclear hGR (4H2) in the binucleated follicular dendritic cells and germinal centre cells. The frequency of hGR (4H2) expression in diffuse large B cell lymphoma was higher, that in mantle cell lymphoma was lower, and that in follicular lymphoma was intermediate among the types of malignant lymphoma. The hGR (4H2) expression was less frequent in cases of grade I follicular lymphoma. CONCLUSIONS There are differences in hGR expression between the germinal centre and the mantle zone in non-neoplastic lymphoid follicles, and differences of hGR (4H2) expression among the types of malignant lymphoma and grades of follicular lymphoma, which probably contribute to the different steroid sensitivities.
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Affiliation(s)
- S-I Okazaki
- Department of Pathology, Yamagata University School of Medicine, Yamagata, Japan
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270
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Dvorák Z, Vrzal R, Maurel P, Ulrichová J. Differential effects of selected natural compounds with anti-inflammatory activity on the glucocorticoid receptor and NF-κB in HeLa cells. Chem Biol Interact 2006; 159:117-28. [PMID: 16289013 DOI: 10.1016/j.cbi.2005.10.105] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 09/27/2005] [Accepted: 10/05/2005] [Indexed: 01/29/2023]
Abstract
Natural compounds have been used in the treatment of various diseases for centuries. Herein, we investigated the effects of structurally diverse alkaloids with anti-inflammatory activity (berberine, sanguinarine, chelerythrine, and colchicine) on two important anti-inflammatory and pro-inflammatory players, i.e. glucocorticoid receptor (GR) and nuclear factor kappa B (NF-kappaB), respectively. Sanguinarine and chelerythrine elicited nuclear translocation of the p65 subunit of NF-kappaB. The nuclear import of p65 was strongly augmented by these akaloids in non-stimulated cells as well as in cells challenged with tumor necrosis factor alpha (TNFalpha). Colchicine and berberine had no effect on p65 nuclear translocation regardless of the presence or absence of TNFalpha. Colchicine caused rapid degradation of the GR protein, whereas berberine had no effect on GR content or cellular localization. Sanguinarine and chelerythrine induced accumulation of GR in the nucleus with concomitant diminution of cytosolic GR. Analyses on the transcriptional activity of GR and NF-kappaB monitored by reporter assays using HeLa cells transiently transfected with glucocorticoid response element (pGRE-LUC) and/or NF-kappaB elements fused to luciferase gene (pNF-kappaB-luc) showed that none of the compounds tested had the capability to trigger GR and/or NF-kappaB transcriptional activities, respectively. The ligand binding assay showed that colchicine and berberine are not GR ligands whereas sanguinarine and chelerythrine significantly decreased binding of (3)H-labelled dexamethasone to GR. In conclusion, structurally diverse natural antiflogistics displayed differential effects on GR and NF-kappaB in HeLa cells.
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Affiliation(s)
- Zdenek Dvorák
- Institute of Medical Chemistry and Biochemistry, Medical Faculty, Palacký University Olomouc, Hnevotínská 3, 77515 Olomouc, Czech Republic.
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271
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Matsune S, Sun D, Ohori J, Nishimoto K, Fukuiwa T, Ushikai M, Kurono Y. Inhibition of vascular endothelial growth factor by macrolides in cultured fibroblasts from nasal polyps. Laryngoscope 2006; 115:1953-6. [PMID: 16319604 DOI: 10.1097/01.mlg.0000177031.06112.50] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE In order to study a new mechanism of efficacy of 14-membered ring macrolides in treating chronic rhinosinusitis, inhibitory effects of macrolides on vascular endothelial growth factor production were examined in vitro. METHODS Vascular endothelisal growth factor production in cultured fibloblasts from human nasal polyps obtained from surgery for chronic paranasal sinusitis stimulated by hypoxia or tumor necrosis factor-alpha was assessed under the administration of Clarithromycin or Roxisthromycin by enzyme linked immunosorbent assay and reverse transcriptase polymerase chain-reaction. RESULTS Dose-dependent inhibitory effects on vascular endothelisal growth factor production stimulated by hypoxia or tumor necrosis factor-alpha were noted in the groups treated with Clarithromycin and Roxisthromycin, including inhibition of vascular endothelisal growth factor mRNA levels. CONCLUSION While, to date, several evidences have indicated that the mechanisms by which 14-membered ring macrolides reduce inflammation are not simply bactericidal, these results suggest another new mechanism of efficacy of macrolides in treating chronic rhinosinusitis.
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Affiliation(s)
- Shoji Matsune
- Department of Otolaryngology, Head and Neck Surgery, Field of Sensory Organology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
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272
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Oerlemans R, van der Heijden J, Vink J, Dijkmans BAC, Kaspers GJL, Lems WF, Scheffer GL, Ifergan I, Scheper RJ, Cloos J, Assaraf YG, Jansen G. Acquired resistance to chloroquine in human CEM T cells is mediated by multidrug resistance–associated protein 1 and provokes high levels of cross-resistance to glucocorticoids. ACTA ACUST UNITED AC 2006; 54:557-68. [PMID: 16447232 DOI: 10.1002/art.21569] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To explore the onset and molecular mechanism of resistance to the antimalarial disease-modifying antirheumatic drug (DMARD) chloroquine (CQ) in human CEM T cells. METHODS Human CEM cells were used as an in vitro model system to study the development of CQ resistance by growing cells in stepwise increasing concentrations of CQ. RESULTS Over a period of 6 months, CEM cell lines developed 4-5-fold resistance to CQ. CQ resistance was associated with the specific overexpression of multidrug resistance-associated protein 1 (MRP-1), an ATP-driven drug efflux pump. This was illustrated by 1) overexpression of MRP-1 by Western blotting and 2) the complete reversal of CQ resistance by the MRP-1 transport inhibitors MK571 and probenecid. Importantly, CQ-resistant CEM cells retained full sensitivity to other DMARDs, including methotrexate, leflunomide, cyclosporin A, and sulfasalazine, but exhibited a high level of cross-resistance (>1,000-fold) to the glucocorticoid dexamethasone. The mechanistic basis for the latter was associated with aberrant signaling via the cAMP-protein kinase A pathway, since the cAMP-inducing agent forskolin reversed dexamethasone resistance. Finally, CQ-resistant CEM cells displayed a markedly reduced capacity to release proinflammatory cytokines (tumor necrosis factor alpha) and chemokines (interleukin-8). CONCLUSION Induction of overexpression of the multidrug resistance efflux transporter MRP-1 can emerge after long-term exposure to CQ and results in CQ resistance and collateral resistance to dexamethasone. These findings warrant further detailed investigations into the possible role of MRP-1 and other members of the superfamily of drug efflux pumps in diminishing the efficacy of DMARDs in rheumatoid arthritis treatment.
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Affiliation(s)
- Ruud Oerlemans
- VU University Medical Center, Amsterdam, The Netherlands
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273
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Abstract
The molecular mechanisms whereby PPARgamma inhibits inflammatory gene expression in macrophages are poorly understood. In a recent Nature paper, provide a new model for trans-repression in which ligand-dependent SUMOylation of PPARgamma results in its recruitment to the promoters of inflammatory genes where it inhibits transcription by preventing clearance of corepressor complexes.
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Affiliation(s)
- Noam Zelcer
- Howard Hughes Medical Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, California 90055, USA
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274
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Betageri R, Zhang Y, Zindell RM, Kuzmich D, Kirrane TM, Bentzien J, Cardozo M, Capolino AJ, Fadra TN, Nelson RM, Paw Z, Shih DT, Shih CK, Zuvela-Jelaska L, Nabozny G, Thomson DS. Trifluoromethyl group as a pharmacophore: Effect of replacing a CF3 group on binding and agonist activity of a glucocorticoid receptor ligand. Bioorg Med Chem Lett 2005; 15:4761-9. [PMID: 16112571 DOI: 10.1016/j.bmcl.2005.07.025] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 07/20/2005] [Accepted: 07/21/2005] [Indexed: 11/25/2022]
Abstract
Compound 1, a potent glucocorticoid receptor ligand, contains a quaternary carbon bearing trifluoromethyl and hydroxyl groups. This paper describes the effect of replacing the trifluoromethyl group on binding and agonist activity of the GR ligand 1. The results illustrate that replacing the CF3 group with a cyclohexylmethyl or benzyl group maintains the GR binding potency. These substitutions alter the functional behavior of the GR ligands from agonists to antagonists. Docking studies suggest that the benzyl analog 19 binds in a similar fashion as the GR antagonist, RU486. The central benzyl group of 19 and the C-11 dimethylaniline moiety of RU486 overlay. Binding of compound 19 is believed to force helix 12 to adopt an open conformation and this leads to the antagonist properties of the non-CF3 ligands carrying a large group at the center of the molecule.
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Affiliation(s)
- Raj Betageri
- Department of Medicinal Chemistry, Boehringer Ingelheim Pharmaceuticals Inc., 900 Ridgebury Road, P.O. Box 368, Ridgefield, CT 06877, USA.
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275
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SILVERMAN MARNIN, PEARCE BRADD, BIRON CHRISTINEA, MILLER ANDREWH. Immune modulation of the hypothalamic-pituitary-adrenal (HPA) axis during viral infection. Viral Immunol 2005; 18:41-78. [PMID: 15802953 PMCID: PMC1224723 DOI: 10.1089/vim.2005.18.41] [Citation(s) in RCA: 325] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Compelling data has been amassed indicating that soluble factors, or cytokines, emanating from the immune system can have profound effects on the neuroendocrine system, in particular the hypothalamic- pituitary-adrenal (HPA) axis. HPA activation by cytokines (via the release of glucocorticoids), in turn, has been found to play a critical role in restraining and shaping immune responses. Thus, cytokine-HPA interactions represent a fundamental consideration regarding the maintenance of homeostasis and the development of disease during viral infection. Although reviews exist that focus on the bi-directional communication between the immune system and the HPA axis during viral infection (188,235), others have focused on the immunomodulatory effects of glucocorticoids during viral infection (14,225). This review, however, concentrates on the other side of the bi-directional loop of neuroendocrine-immune interactions, namely, the characterization of HPA axis activity during viral infection and the mechanisms employed by cytokines to stimulate glucocorticoid release.
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Affiliation(s)
- MARNI N. SILVERMAN
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
| | - BRAD D. PEARCE
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
| | - CHRISTINE A. BIRON
- Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Providence, Rhode Island
| | - ANDREW H. MILLER
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia
- Address reprint requests to: Dr. Andrew H. Miller, Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 101 Woodruff Circle, WMRB Suite 4000, Atlanta, Georgia 30322, E-mail:
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276
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Chen B, Tsui S, Smith TJ. IL-1β Induces IL-6 Expression in Human Orbital Fibroblasts: Identification of an Anatomic-Site Specific Phenotypic Attribute Relevant to Thyroid-Associated Ophthalmopathy. THE JOURNAL OF IMMUNOLOGY 2005; 175:1310-9. [PMID: 16002736 DOI: 10.4049/jimmunol.175.2.1310] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human orbital fibroblasts exhibit a unique inflammatory phenotype. In the present study, we report that these fibroblasts, when treated with IL-1beta, express high levels of IL-6, a cytokine involved in B cell activation and the regulation of adipocyte metabolism. The magnitude of this induction is considerably greater than that in dermal fibroblasts and involves up-regulation of IL-6 mRNA levels. IL-1beta activates both p38 and ERK 1/2 components of the MAPK pathways. Disrupting these could attenuate the IL-6 induction. The up-regulation involves enhanced IL-6 gene promoter activity and retardation of IL-6 mRNA decay by IL-1beta. Dexamethasone completely blocked the effect of IL-1beta on IL-6 expression. Orbital fibroblasts also express higher levels of IL-6R than do skin-derived cells. When treated with rIL-6 (10 ng/ml), STAT3 is transiently phosphorylated. Thus, the exaggerated capacity of orbital fibroblasts to express high levels of both IL-6 and its receptor in an anatomic site-selective manner could represent an important basis for immune responses localized to the orbit in Graves' disease.
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Affiliation(s)
- Beiling Chen
- Division of Molecular Medicine, Department of Medicine, Harbor-University of California at Los Angeles, Medical Center, 1124 West Carson Street, Torrance, CA 90502, USA
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