ORCID Profile
0000-0002-9529-9943
Current Organisation
University of Ottawa
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Publisher: Springer Science and Business Media LLC
Date: 10-05-2011
Abstract: Glucocorticoids have been exploited therapeutically for more than six decades through the use of synthetic glucocorticoids as anti-inflammatory agents, and are still used in as many as 50% of patients suffering from inflammatory diseases such as rheumatoid arthritis (RA). Better understanding of the mechanisms of action of glucocorticoids could enable the development of therapies that dissociate the broad-spectrum benefits of glucocorticoids from their adverse metabolic effects. The glucocorticoid-induced leucine zipper protein (GILZ also known as TSC22 domain family protein 3) is a glucocorticoid-responsive molecule whose interactions with signal transduction pathways, many of which are operative in RA and other inflammatory diseases, suggest that it is a key endogenous regulator of the immune response. The overlap between the observed effects of GILZ on the immune system and those of glucocorticoids strongly suggest GILZ as a critical mediator of the therapeutic effects of glucocorticoids. Observations of the immunomodulatory effects of GILZ in human RA synovial cells, and in an in vivo model of RA, support the hypothesis that GILZ is a key glucocorticoid-induced regulator of inflammation in RA. Moreover, evidence that the effect of GILZ on bone loss might be in contrast to those of glucocorticoids suggests manipulation of GILZ as a potential means of dissociating the beneficial anti-inflammatory effects of glucocorticoids from their negative metabolic repercussions.
Publisher: American Society for Microbiology
Date: 06-2000
DOI: 10.1128/IAI.68.6.3200-3209.2000
Abstract: Immunoblotting sera from 26 patients with septicemia due to an epidemic strain of methicillin-resistant Staphylococcus aureus (EMRSA-15), 6 of whom died, revealed an immunodominant EMRSA-15 antigen at 61 kDa. There was a statistically significant correlate ( P 0.001) between survival and immunoglobulin G to the 61-kDa band. The antigen was identified by sequencing positive clones obtained by screening a genomic expression library of EMRSA-15 with pooled sera from patients taken after the septicemic episode. Eluted antibody reacted with the 61-kDa antigen on immunoblots. The amino terminus was obtained by searching the S. aureus NCTC 8325 and MRSA strain COL databases, and the whole protein was expressed in Escherichia coli TOP 10F′. The derived amino acid sequence showed homology with ABC transporters, with paired Walker A and Walker B motifs and 73% homology to YkpA from Bacillus subtilis . Epitope mapping of the derived amino acid sequence with sera from patients who had recovered from EMRSA-15 septicemia delineated seven epitopes. Three of these epitopes, represented by peptides 1 (KIKVYVGNYDFWYQS), 2 (TVIVVSHDRHFLYNNV), and 3 (TETFLRGFLGRMLFS), were synthesized and used to isolate human recombinant antibodies from a phage antibody display library. Recombinant antibodies against peptides 1 and 2 gave logarithmic reductions in organ colony counts, compared with control groups, in a mouse model of the infection. This study suggests the potential role of an ABC transporter as a target for immunotherapy.
Publisher: Wiley
Date: 30-07-2009
DOI: 10.1002/ART.24659
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.CELREP.2019.07.088
Abstract: In the ovary, follicular growth and maturation are complicated processes that involve a series of morphological and physiological changes in oocytes and somatic cells leading to ovulation and luteinization, essential processes for fertility. Given the complexity of ovulation, characterization of genome-wide regulatory elements is essential to understand the mechanisms governing the expression of specific genes in the rapidly differentiating follicle. We therefore employed a systems biology approach to determine global transcriptional mechanisms during the early stages of the ovulatory process. We demonstrate that, following the hormonal signal that initiates ovulation, granulosa cells undergo major modification of distal regulatory elements, which coincides with cistrome reprogramming of the indispensable orphan nuclear receptor liver receptor homolog-1 (LRH-1). This cistromic reorganization correlates with the extensive changes in gene expression in granulosa cells leading to ovulation. Together, our study yields a highly detailed transcriptional map delineating ovarian cell differentiation during the initiation of ovulation.
Publisher: Public Library of Science (PLoS)
Date: 14-03-2013
Publisher: Wiley
Date: 31-08-2010
DOI: 10.1002/ART.27566
Abstract: Glucocorticoid-induced leucine zipper (GILZ) is a glucocorticoid-induced protein, the reported molecular interactions of which suggest that it functions to inhibit inflammation. However, the role of endogenous GILZ in the regulation of inflammation in vivo has not been established. This study was undertaken to examine the expression and function of GILZ in vivo in collagen-induced arthritis (CIA), a murine model of rheumatoid arthritis (RA), and in RA synoviocytes. GILZ expression was detected in mouse and human synovium by immunohistochemistry and in cultured cells by real-time polymerase chain reaction and permeabilization flow cytometry. GILZ function was assessed in vivo by small interfering RNA (siRNA) silencing using cationic liposome-encapsulated GILZ or control nontargeting siRNA and was assessed in vitro using transient overexpression. GILZ was readily detectable in the synovium of mice with CIA and was up-regulated by therapeutic doses of glucocorticoids. Depleting GILZ expression in vivo increased the clinical and histologic severity of CIA and increased synovial expression of tumor necrosis factor and interleukin-1 (IL-1), without affecting the levels of circulating cytokines or anticollagen antibodies. GILZ was highly expressed in the synovium of patients with active RA and in cultured RA synovial fibroblasts, and GILZ overexpression in synovial fibroblasts inhibited IL-6 and IL-8 release. Our findings indicate that GILZ functions as an endogenous inhibitor of chronic inflammation via effects on cytokine expression and suggest that local modulation of GILZ expression could be a beneficial therapeutic strategy.
Publisher: Oxford University Press (OUP)
Date: 19-11-2010
DOI: 10.1111/J.1365-2249.2010.04289.X
Abstract: The aim of this study was to determine the genetic regulation of macrophage migration inhibitory factor (MIF). DNase I hypersensitivity was used to identify potential hypersensitive sites (HS) across the MIF gene locus. Reporter gene assays were performed in different human cell lines with constructs containing the native or mutated HS element. Following phylogenetic and transcription factor binding profiling, electrophoretic mobility shift assay (EMSA) and RNA interference were performed and the effects of incubation with mithramycin, an antibiotic that binds GC boxes, were also studied. An HS centred on the first intron of MIF was identified. The HS acted as an enhancer in human T lymphoblasts (CEMC7A), human embryonic kidney cells (HEK293T) and human monocytic cells (THP-1), but not in a fibroblast-like synoviocyte (FLS) cell line (SW982) or cultured FLS derived from rheumatoid arthritis (RA) patients. Two cis-elements within the first intron were found to be responsible for the enhancer activity. Mutation of the consensus Sp1 GC box on each cis-element abrogated enhancer activity and EMSA indicated Sp1 binding to one of the cis-elements contained in the intron. SiRNA knock-down of Sp1 alone or Sp1 and Sp3 together was incomplete and did not alter the enhancer activity. Mithramycin inhibited expression of MIF in CEMC7A cells. This effect was specific to the intronic enhancer and was not seen on the MIF promoter. These results identify a novel, cell type-specific enhancer of MIF. The enhancer appears to be driven by Sp1 or related Sp family members and is highly sensitive to inhibition via mithramycin.
Publisher: Wiley
Date: 28-07-2014
DOI: 10.1002/ART.38689
Publisher: The American Association of Immunologists
Date: 07-2013
Abstract: Glucocorticoid-induced leucine zipper (GILZ) is an anti-inflammatory protein first identified in T lymphocytes. We recently observed that GILZ is highly expressed in synovial endothelial cells in rheumatoid arthritis. However, the function of GILZ in endothelial cells is unknown. To investigate the actions of GILZ in this cell type, we induced GILZ expression in HUVECs via transient transfection. GILZ overexpression significantly reduced the capacity of TNF-stimulated HUVECs to support leukocyte rolling, adhesion, and transmigration. These effects were associated with decreased expression of E-selectin, ICAM-1, CCL2, CXCL8, and IL-6. Experiments in a human microvascular endothelial cell line demonstrated that TNF-inducible NF-κB activity was significantly inhibited by overexpression of GILZ. Exogenous GILZ inhibited TNF-induced NF-κB p65 DNA binding, although this occurred in the absence of an effect on p65 nuclear translocation, indicating that the mechanism of action of exogenous GILZ in endothelial cells differs from that reported in other cell types. GILZ overexpression also inhibited TNF-induced activation of p38, ERK, and JNK MAPKs, as well as increased expression of the MAPK inhibitory phosphatase, MKP-1. In contrast, silencing endogenous GILZ in glucocorticoid-treated HUVECs did not alter their capacity to support leukocyte interactions. These data demonstrate that exogenous GILZ exerts inhibitory effects on endothelial cell adhesive function via a novel pathway involving modulation of NF-κB p65 DNA binding and MAPK activity. Induction of GILZ expression in endothelial cells may represent a novel therapeutic modality with the potential to inhibit inflammatory leukocyte recruitment.
Publisher: Wiley
Date: 23-04-2013
DOI: 10.1002/ART.37858
Abstract: Glucocorticoid-induced leucine zipper (GILZ) has effects on inflammatory pathways that suggest it to be a key inhibitory regulator of the immune system, and its expression is exquisitely sensitive to induction by glucocorticoids. We undertook this study to test our hypothesis that GILZ deficiency would exacerbate experimental immune-mediated inflammation and impair the effects of glucocorticoids on inflammation and, correspondingly, that exogenous GILZ would inhibit these events. GILZ(-/-) mice were generated using the Cre/loxP system, and responses were studied in delayed-type hypersensitivity (DTH), antigen-induced arthritis (AIA), K/BxN serum-transfer arthritis, and lipopolysaccharide (LPS)-induced cytokinemia. Therapeutic expression of GILZ via administration of recombinant adeno-associated virus expressing the GILZ gene (GILZ-rAAV) was compared to the effects of glucocorticoid in collagen-induced arthritis (CIA). Increased T cell proliferation and DTH were observed in GILZ(-/-) mice, but neither AIA nor K/BxN serum-transfer arthritis was affected, and GILZ deficiency did not affect LPS-induced cytokinemia. Deletion of GILZ did not impair the effects of exogenous glucocorticoids on CIA or cytokinemia. In contrast, overexpression of GILZ in joints significantly inhibited CIA, with an effect similar to that of dexamethasone. Despite effects on T cell activation, GILZ deficiency had no effect on effector pathways of arthritis and was unexpectedly redundant with effects of glucocorticoids. These findings do not support the hypothesis that GILZ is central to the actions of glucocorticoids, but the efficacy of exogenous GILZ in CIA suggests that further evaluation of GILZ in inflammatory disease is required.
Publisher: The American Association of Immunologists
Date: 15-05-2015
Abstract: Glucocorticoid (GC)-induced leucine zipper (GILZ) has been shown to mediate or mimic several actions of GC. This study assessed the role of GILZ in self-resolving and GC-induced resolution of neutrophilic inflammation induced by LPS in mice. GILZ expression was increased during the resolution phase of LPS-induced pleurisy, especially in macrophages with resolving phenotypes. Pretreating LPS-injected mice with trans-activator of transcription peptide (TAT)–GILZ, a cell-permeable GILZ fusion protein, shortened resolution intervals and improved resolution indices. Therapeutic administration of TAT-GILZ induced inflammation resolution, decreased cytokine levels, and promoted caspase-dependent neutrophil apoptosis. TAT-GILZ also modulated the activation of the survival-controlling proteins ERK1/2, NF-κB and Mcl-1. GILZ deficiency was associated with an early increase of annexin A1 (AnxA1) and did not modify the course of neutrophil influx induced by LPS. Dexamethasone treatment resolved inflammation and induced GILZ expression that was dependent on AnxA1. Dexamethasone-induced resolution was not altered in GILZ−/− mice due to compensatory expression and action of AnxA1. Our results show that therapeutic administration of GILZ efficiently induces a proapoptotic program that promotes resolution of neutrophilic inflammation induced by LPS. Alternatively, a lack of endogenous GILZ during the resolution of inflammation is compensated by AnxA1 overexpression.
Publisher: The Endocrine Society
Date: 12-2012
DOI: 10.1210/EN.2012-1380
Abstract: Adipogenesis, the biological process by which preadipocytes differentiate into mature fat cells, is coordinated by a tightly regulated gene expression program. Indeed, it has been reported that a large number of genetic events, from fat cell-specific transcription factors expression, such as the master regulator of fat cell differentiation peroxisome proliferator-activated receptor (PPAR)γ2 to epigenetic modifications, govern the acquisition of a mature adipocyte phenotype. Here, we provide evidence that the E1A-binding protein p400 (p400) complex subunit bromo-containing protein 8 (Brd8) plays an important role in the regulation of PPARγ target genes during adipogenesis by targeting and incorporating the histone variant H2A.Z in transcriptional regulatory regions. The results reported here indicate that expression of both Brd8 and p400 increases during fat cell differentiation. In addition, small hairpin RNA-mediated knockdown of Brd8 or H2A.Z completely abrogated the ability of 3T3-L1 preadipocyte to differentiate into mature adipocyte, as evidenced by a lack of lipid accumulation. Chromatin immunoprecipitation experiments also revealed that the knockdown of Brd8 blocked the accumulation of PPARγ, p400, and RNA polymerase II and prevented the incorporation of H2A.Z at two PPARγ target genes. Taken together, these results indicate that the incorporation of the histone variant H2A.Z at the promoter regions of PPARγ target genes by p400/Brd8 is essential to allow fat cell differentiation.
Publisher: Public Library of Science (PLoS)
Date: 24-03-2015
Publisher: Wiley
Date: 25-05-2015
DOI: 10.1002/ART.39069
Abstract: Mesenchymal stem cells (MSCs) are potent immunosuppressive cells that have shown promise in the treatment of rheumatoid arthritis (RA). Deciphering the intrinsic characteristics of MSCs that correlate with their biologic activity will facilitate their clinical use. Recently, the role of glucocorticoid‐induced leucine zipper (GILZ) in the development of RA has been documented. The aim of this study was to evaluate whether GILZ expression by MSCs may contribute to their therapeutic effect. MSCs were isolated from GILZ‐deficient (GILZ −/− ) mice and wild‐type mice. MSCs (1 × 10 6 cells) were injected twice via the tail vein into mice with collagen‐induced arthritis (CIA). In vitro, we showed that GILZ is a key factor involved in the immunosuppressive potential of MSCs. MSCs derived from GILZ −/− mice did not suppress the proliferation of CD4+ T cells and were less efficient than MSCs derived from WT mice in altering Th17 cell polarization. Thus, we investigated the role of GILZ in an experimental model of arthritis and demonstrated that although WT MSCs significantly reduced paw swelling in arthritic mice, GILZ −/− MSCs did not. Moreover, the magnitude of the effects of GILZ −/− MSCs on Th17 cell frequency was significantly lower than that of WT MSCs. The therapeutic effect of MSCs correlated with the generation of Treg cells bearing the CD4 + RORγt+IL‐17 low IL‐10+ signature, and Th17 cell polarization was GILZ dependent. This study demonstrates that GILZ has an essential role in the therapeutic effectiveness of MSCs in arthritis by favoring Th17 cell polarization toward a regulatory phenotype. Therefore, potentiation of GILZ expression in MSCs could represent a means to enhance their therapeutic effect in autoimmune diseases.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Elaine Beaulieu.