Suppression of monosodium urate crystal-induced cytokine production by butyrate is mediated by the inhibition of class I histone deacetylases

2015 ◽  
Vol 75 (3) ◽  
pp. 593-600 ◽  
Author(s):  
Maartje C P Cleophas ◽  
Tania O Crişan ◽  
Heidi Lemmers ◽  
Helga Toenhake-Dijkstra ◽  
Gianluca Fossati ◽  
...  
Keyword(s):  
Hdac Inhibitor ◽  
Histone Deacetylases ◽  
Mononuclear Cells ◽  
Cytokine Production ◽  
Hdac Inhibitors ◽  
Class I ◽  
Acute Gout ◽  
Monosodium Urate ◽  
Healthy Donors ◽  
Anti Inflammatory

ObjectivesAcute gouty arthritis is caused by endogenously formed monosodium urate (MSU) crystals, which are potent activators of the NLRP3 inflammasome. However, to induce the release of active interleukin (IL)-1β, an additional stimulus is needed. Saturated long-chain free fatty acids (FFAs) can provide such a signal and stimulate transcription of pro-IL-1β. In contrast, the short-chain fatty acid butyrate possesses anti-inflammatory effects. One of the mechanisms involved is inhibition of histone deacetylases (HDACs). Here, we explored the effects of butyrate on MSU+FFA-induced cytokine production and its inhibition of specific HDACs.MethodsFreshly isolated peripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with MSU and palmitic acid (C16.0) in the presence or absence of butyrate or a synthetic HDAC inhibitor. Cytokine responses were measured with ELISA and quantitative PCR. HDAC activity was measured with fluorimetric assays.ResultsButyrate decreased C16.0+MSU-induced production of IL-1β, IL-6, IL-8 and IL-1β mRNA in PBMCs from healthy donors. Similar results were obtained in PBMCs isolated from patients with gout. Butyrate specifically inhibited class I HDACs. The HDAC inhibitor, panobinostat and the potent HDAC inhibitor, ITF-B, also decreased ex vivo C16.0+MSU-induced IL-1β production.ConclusionsIn agreement with the reported low inhibitory potency of butyrate, a high concentration was needed for cytokine suppression, whereas synthetic HDAC inhibitors showed potent anti-inflammatory effects at nanomolar concentrations. These novel HDAC inhibitors could be effective in the treatment of acute gout. Moreover, the use of specific HDAC inhibitors could even improve the efficacy and reduce any potential adverse effects.

Abstract 238: Class I HDAC inhibition prevents Ncx1 upregulation by stabilizing an HDAC5-HDAC1/Sin3a Repressor Complex during cardiac hypertrophy.

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Sabina Wang ◽  
Lillianne G Harris ◽  
Santhosh Mani ◽  
Donald Menick
Keyword(s):  
Cardiac Hypertrophy ◽  
Hdac Inhibitor ◽  
Histone Deacetylases ◽  
Hdac Inhibitors ◽  
Class I ◽  
Proximal Promoter ◽  
Hdac Inhibition ◽  
Repressor Complex

Cardiac hypertrophy is often associated with the activation of signaling pathways that perpetuate altered calcium efflux and influx. One gene that is upregulated and contributes to altered intracellular calcium concentrations and worsening contractility during cardiac hypertrophy is the Sodium Calcium Exchanger ( Ncx1 ). Molecular studies implicate histone deacetylases (HDACs) in possibly regulating the expression of this gene. Our recent work reveals that HDAC1, HDAC5 and Sin3a interact and are recruited to the Ncx1 promoter through the Nkx2.5 transcription factor. Interestingly, we observed greater associated/interaction of the HDAC1-HDAC5/Sin3a repressor complex upon broad HDAC inhibition. Taken together, we hypothesized that HDAC inhibition, stabilizes an HDAC1-HDAC5/Sin3a repressor complex during cardiac hypertrophy. We addressed this hypothesis by treating isolated adult cardiomyocytes with class specific HDAC inhibitors since HDAC1 is a Class I HDAC and HDAC5 is a Class IIa HDAC. Co-Immunoprecipitation (Co-IP) revealed a greater association of repressor complex molecules in the presence of Entinostat, a Class I HDAC inhibitor compared to both non-treated control and TSA, a broad HDAC inhibitor (n=3). These works show enhanced recruitment Sin3a (co-repressor) at the proximal promoter of NCX1 as demonstrated by Chromatin-Immunoprecipitation (ChIP) (n=3). To test whether these observations translated into in vivo models, we subjected mice to transaortic constriction (TAC) to induce hypertrophy. In this model, Co-IP revealed results that similar to our in vitro studies with greater immuno- detection of repressor complex component, Sin3a after immune-precipitation with HDAC1. Furthermore, our ChIP data showed a greater PCR product amplification of proximal Ncx1 promoter, from experimental groups that were subjected to Entinostat (n=3). Our cumulative data suggests that Class I HDAC inhibition stabilizes a repressor complex on the Ncx1 promoter that hinders hypertrophy- mediated Ncx1 upregulation. Class specific HDAC inhibition may be useful in the stabilization and repression of aberrantly expressed genes that contribute to poor clinical outcomes in cardiac hypertrophy.

scholarly journals HDAC inhibitors impair Fshb subunit expression in murine gonadotrope cells

2019 ◽  
Vol 62 (2) ◽  
pp. 67-78 ◽  
Author(s):  
Gauthier Schang ◽  
Chirine Toufaily ◽  
Daniel J Bernard
Keyword(s):  
Hdac Inhibitor ◽  
Histone Deacetylases ◽  
Trichostatin A ◽  
Hdac Inhibitors ◽  
Class I ◽  
Subunit Expression ◽  
Beta Subunit Gene ◽  
Underlying Mechanisms

Fertility is dependent on follicle-stimulating hormone (FSH), a product of gonadotrope cells of the anterior pituitary gland. Hypothalamic gonadotropin-releasing hormone (GnRH) and intra-pituitary activins are regarded as the primary drivers of FSH synthesis and secretion. Both stimulate expression of the FSH beta subunit gene (Fshb), although the underlying mechanisms of GnRH action are poorly described relative to those of the activins. There is currently no consensus on how GnRH regulates Fshb transcription, as results vary across species and between in vivo and in vitro approaches. One of the more fully developed models suggests that the murine Fshb promoter is tonically repressed by histone deacetylases (HDACs) and that GnRH relieves this repression, at least in immortalized murine gonadotrope-like cells (LβT2 and αT3-1). In contrast, we observed that the class I/II HDAC inhibitor trichostatin A (TSA) robustly inhibited basal, activin A-, and GnRH-induced Fshb mRNA expression in LβT2 cells and in primary murine pituitary cultures. Similar results were obtained with the class I specific HDAC inhibitor, entinostat, whereas two class II-specific inhibitors, MC1568 and TMP269, had no effects on Fshb expression. Collectively, these data suggest that class I HDACs are positive, not negative, regulators of Fshb expression in vitro and that, contrary to earlier reports, GnRH may not stimulate Fshb by inhibiting HDAC-mediated repression of the gene.

scholarly journals AB0043 EFFECT OF ANTI-INFLAMMATORY MEDICATION ON INTERACTION OF SYNOVIAL FIBROBLASTS WITH MACROPHAGES IN RHEUMATOID ARTHRITIS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1054.1-1054
Author(s):  
M. Schmeller ◽  
M. Diller ◽  
R. Hasseli ◽  
A. Knothe ◽  
S. Rehart ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mononuclear Cells ◽  
Joint Inflammation ◽  
Synovial Fibroblasts ◽  
Therapeutic Effects ◽  
Synergistic Activity ◽  
M1 Macrophages ◽  
Healthy Donors ◽  
Proinflammatory Activity ◽  
Anti Inflammatory

Background:One of the key mechanisms in the pathogenesis of rheumatoid arthritis (RA) is the interaction of macrophages and synovial fibroblasts during joint inflammation. Increased synergistic proinflammatory activity of both cell types leads to the release of high levels of proinflammatory cytokines, especially of interleukin-6 (IL-6), and of matrix degrading enzymes. If this mechanism is uncontrolled, progressive destruction of articular cartilage and bone will take place.In active disease, immediate anti-inflammatory treatment with glucocorticoids is usually replaced by disease-modifying anti-rheumatic drugs (DMARDS), especially by methotrexate (MTX) and biologics such as TNF-α- or IL-6-inhibitors. This led to great improvements in prognosis and outcome for RA patients. However, about 40% of patients experience no remission or suffer from side effects of medication. To optimize established substances and to develop new treatment strategies, it is necessary to understand the mechanisms underlying the limited therapeutic effects.Objectives:Evaluation of the effect of prednisolone, MTX, adalimumab, tocilizumab on IL-6 secretion by RA synovial fibroblasts (RASF) and macrophages.Methods:RA synovium was used for RASF isolation. Peripheral blood mononuclear cells (PBMCs) were isolated from blood of healthy donors and RA patients by using Ficoll© medium followed by density gradient centrifugation. Mononuclear cells were seeded on six well plates (6x10^6/well) and incubated for one week. Then they were stimulated with Interferon-у (20 ng/ml) and LPS (50 ng/ml) for 48h to initiate differentiation into proinflammatory M1 macrophages. The M1 macrophages were co-cultured with RASF (100.000/well) and different treatments added (prednisolone: 10, 25, 50, 75, 100 nM, 1 µM; adalimumab: 100, 500 µg/ml; tocilizumab: 1, 5 µg/ml; MTX: 0,5, 1, 5, 10, 100 nM, 1µM). After 24h culture supernatants were collected and IL-6- and TNFα-ELISAs were performed.Results:IL-6 concentrations of untreated controls were comparable, regardless whether M1 macrophages from healthy donors or RA-patients were used for co-culture. Prednisolone reduced co-culture-induced IL-6 up to 56% (p<0.001) in co-culture of RASF and M1 macrophages of healthy donors and up to 60% (p<0.001) in co-culture of RASF and RA M1 macrophages. Adalimumab reduced IL-6 up to 28% (p<0.05) in M1 of healthy donors and up to 45% (p<0.01) in RA M1 macrophage co-cultures. A minor reduction by 10-20% of IL-6 was observed with tocilizumab and no significant effect could be achieved after treatment with MTX.Conclusion:Prednisolone and adalimumab clearly decrease but do not eliminate proinflammatory synergistic activity of RASF and M1 macrophages. These results confirm the clinical observation, that there is a large number of RA-patients that independent of anti-inflammatory treatment still suffer from low-level joint inflammation.The synergistic proinflammatory activity of M1 macrophages and RASF seems to be a complex and multifactorial mechanism that is difficult to eliminate by a single treatment substance. Since it is one of the key mechanisms in RA pathogenesis, there is a critical need to investigate how therapy effects could be optimized. This study confirmed RASFs as one of the leading effector cells of increased synergistic proinflammatory activity, thus underlining their promising role as a treatment target in rheumatoid arthritis.Disclosure of Interests:None declared

scholarly journals Inhibition of class I histone deacetylase activity represses matrix metalloproteinase-2 and -9 expression and preserves LV function postmyocardial infarction

2015 ◽  
Vol 308 (11) ◽  
pp. H1391-H1401 ◽  
Author(s):  
Santhosh K. Mani ◽  
Christine B. Kern ◽  
Denise Kimbrough ◽  
Benjamin Addy ◽  
Harinath Kasiganesan ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Hdac Inhibitor ◽  
Histone Deacetylases ◽  
Left Ventricular ◽  
Class I ◽  
Matrix Metalloproteinase 2 ◽  
Lv Function ◽  
Extracellular Matrix Remodeling ◽  
Matrix Remodeling ◽  
Lv Remodeling

Left ventricular (LV) remodeling, after myocardial infarction (MI), can result in LV dilation and LV pump dysfunction. Post-MI induction of matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, have been implicated as causing deleterious effects on LV and extracellular matrix remodeling in the MI region and within the initially unaffected remote zone. Histone deacetylases (HDACs) are a class of enzymes that affect the transcriptional regulation of genes during pathological conditions. We assessed the efficacy of both class I/IIb- and class I-selective HDAC inhibitors on MMP-2 and MMP-9 abundance and determined if treatment resulted in the attenuation of adverse LV and extracellular matrix remodeling and improved LV pump function post-MI. MI was surgically induced in MMP-9 promoter reporter mice and randomized for treatment with a class I/IIb HDAC inhibitor for 7 days post-MI. After MI, LV dilation, LV pump dysfunction, and activation of the MMP-9 gene promoter were significantly attenuated in mice treated with either the class I/IIb HDAC inhibitor tichostatin A or suberanilohydroxamic acid (voronistat) compared with MI-only mice. Immunohistological staining and zymographic levels of MMP-2 and MMP-9 were reduced with either tichostatin A or suberanilohydroxamic acid treatment. Class I HDAC activity was dramatically increased post-MI. Treatment with the selective class I HDAC inhibitor PD-106 reduced post-MI levels of both MMP-2 and MMP-9 and attenuated LV dilation and LV pump dysfunction post-MI, similar to class I/IIb HDAC inhibition. Taken together, these unique findings demonstrate that selective inhibition of class I HDACs may provide a novel therapeutic means to attenuate adverse LV remodeling post-MI.

scholarly journals Histone Deacetylation Inhibitors as Therapy Concept in Sepsis

2019 ◽  
Vol 20 (2) ◽  
pp. 346 ◽  
Author(s):  
Andreas von Knethen ◽  
Bernhard Brüne
Keyword(s):  
Organ Failure ◽  
Expression Profile ◽  
Histone Deacetylases ◽  
Hdac Inhibitors ◽  
Histone Deacetylation ◽  
Histone Acetyltransferases ◽  
Open Chromatin ◽  
Nucleosome Structure ◽  
Active Transcription ◽  
Anti Inflammatory

Sepsis is characterized by dysregulated gene expression, provoking a hyper-inflammatory response occurring in parallel to a hypo-inflammatory reaction. This is often associated with multi-organ failure, leading to the patient’s death. Therefore, reprogramming of these pro- and anti-inflammatory, as well as immune-response genes which are involved in acute systemic inflammation, is a therapy approach to prevent organ failure and to improve sepsis outcomes. Considering epigenetic, i.e., reversible, modifications of chromatin, not altering the DNA sequence as one tool to adapt the expression profile, inhibition of factors mediating these changes is important. Acetylation of histones by histone acetyltransferases (HATs) and initiating an open-chromatin structure leading to its active transcription is counteracted by histone deacetylases (HDACs). Histone deacetylation triggers a compact nucleosome structure preventing active transcription. Hence, inhibiting the activity of HDACs by specific inhibitors can be used to restore the expression profile of the cells. It can be assumed that HDAC inhibitors will reduce the expression of pro-, as well as anti-inflammatory mediators, which blocks sepsis progression. However, decreased cytokine expression might also be unfavorable, because it can be associated with decreased bacterial clearance.

scholarly journals Induction of Pro- and Anti-Inflammatory Cytokines by Borrelia burgdorferi Lipoproteins in Monocytes Is Mediated by CD14

1999 ◽  
Vol 67 (1) ◽  
pp. 140-147 ◽  
Author(s):  
Guillermo H. Giambartolomei ◽  
Vida A. Dennis ◽  
Barbara L. Lasater ◽  
Mario T. Philipp
Keyword(s):  
Borrelia Burgdorferi ◽  
Inflammatory Cytokines ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Cytokine Production ◽  
Human Peripheral Blood ◽  
Peptide Sequence ◽  
Monocytic Cell ◽  
Anti Inflammatory ◽  
Pro Inflammatory Cytokines

ABSTRACT We previously showed that heat-killed Borrelia burgdorferi spirochetes and lipidated outer surface protein A (L-OspA) stimulated the in vitro production of interleukin-10 (IL-10) in peripheral blood mononuclear cells (PBMC) from uninfected humans and rhesus monkeys (G. Giambartolomei et al., Infect. Immun. 66:2691–2697, 1998). Here we demonstrate that uninfected human peripheral blood monocytes, but not B or T cells, are the cells that transcribe the IL-10 cytokine gene in response to heat-killed B. burgdorferi. B. burgdorferi similarly induced an upregulation of the IL-1β and IL-6 cytokine genes in monocytes and the production of IL-10 and IL-6 in culture supernatants of the human monocytic cell line THP-1. Purified L-OspA (but not unlipidated OspA [U-OspA] or U-OspC) also stimulated the production of both cytokines in THP-1 cells in a dose-dependent fashion, suggesting that acylation of the OspA protein molecule is required for the production of both anti- and pro-inflammatory cytokines in naive monocytes. A lipohexapeptide that contained the tripalmitoyl-modified cysteine motif (Pam3Cys-Hex) of B. burgdorferi lipoproteins but with an arbitrary peptide sequence had the same effect. Monoclonal antibodies (MAbs) MY4 and 60bca, both of which bind to CD14 and are known to block lipopolysaccharide (LPS)-mediated cytokine production, were able to block L-OspA-mediated IL-10 and IL-6 cytokine production. In contrast, MAb 26ic, which also binds to CD14 but does not block LPS function, failed to inhibit L-OspA-mediated cytokine production. These data suggest that activation of monocytes and production of both anti- and pro-inflammatory cytokines induced by lipoproteins proceeds via the CD14 receptor. LPS binding protein was not required for OspA-induced cytokine production. Our results demonstrate that pro- and anti-inflammatory cytokines induced by B. burgdorferilipoproteins in PBMC are produced by monocytes and that lipoprotein and LPS signaling pathways share at least the initial signaling event that involves the CD14 receptor.

The Histone Deacetylase (HDAC) Inhibitor PCI-24781 Decreases Pro-Inflammatory Cytokine Secretion In Vitro and In Vivo and Protects Against Endotoxemia In a Sepsis Model

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3914-3914
Author(s):  
Sriram Balasubramanian ◽  
Mint Sirisawad ◽  
Susanne Steggerda ◽  
Wangsen Cao ◽  
Charles Lowenstein ◽  
...  
Keyword(s):  
Hdac Inhibitor ◽  
Research Funding ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Employment Equity ◽  
Inflammatory Disorders ◽  
Equity Ownership ◽  
Anti Inflammatory

Abstract Abstract 3914 Inhibitors of histone deacetylases (HDACs) are currently in clinical testing for treating various cancers, and two have been recently approved by the US FDA for treating cutaneous T-cell lymphoma. Here we describe novel anti-inflammatory properties of the HDAC inhibitor PCI-24781 which is in clinical trials for multiple indications including lymphoma (Evens et al., Blood 114: 2726, ASH 2009 Annual Meeting Abstracts). Cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a) have been shown to be involved in human inflammatory disorders, and an anti-IL-6 treatment was recently approved for rheumatoid arthritis (RA). Therefore, the effect of PCI-24781 on cytokine production by lipopolysaccharide (LPS)-stimulated human peripheral mononuclear blood cells (PBMC) as well as isolated monocytes was studied at the RNA expression level by microarrays and Taqman, and at the protein level by ELISA. PCI-24781 potently inhibits the production and secretion of several pro-inflammatory cytokines, including IL-6, TNF-a and interleukin-1beta (IL-1b), at both RNA and protein levels. In murine RAW macrophages as well, PCI-24781 inhibited LPS-stimulated IL-6 secretion at 20nM. PCI-24781 was most effective when given with or before LPS, but was still effective when given an hour after LPS. Similarly, PCI-24781 greatly attenuated in vivo pro-inflammatory cytokine production in LPS-treated Balb/c mice; the IC50 for IL-6 inhibition was < 5 mg/kg. Both the in vitro and in vivo IC50s for IL-6 inhibition are considerably less than the concentrations required to inhibit growth and induce apoptosis in tumor cells (0.2-0.5mM) and in xenograft models (60-80 mg/kg). The mechanism by which these cytokines are controlled involves attenuation of the LPS receptor TLR4 signaling at multiple levels, including acetylation of targets such as MKP-1 and NF-kB subunit p65 in the downstream MAPK and NF-kB pathways; other factors include reduced expression of proteasome, IKK and other NF-kB subunits. Interestingly, we observed a large reduction in levels of NOS2, which causes hypotension during sepsis by producing the inflammatory mediator nitric oxide (NO). Therefore the activity of PCI-24781 was tested in a model of sepsis where mice were treated with a lethal dose of 100 mg/kg LPS, an endotoxin known to be a major mediator of sepsis in humans. PCI-24781 was injected twice, first 16 h before LPS and then 2 h before LPS, in groups of 10 mice each. Control mice that did not receive any PCI-24781 all died within 2 days after LPS (mortality 100%). Pretreatment with PCI-24781 led to dose-dependent increase in survival with 60% of the mice surviving past 6 days with 2 doses of 50mg/kg PCI-24781. These data show that the HDAC inhibitor PCI-24781 protects mice from lethal endotoxemia. Thus, taken together, our data suggest that PCI-24781 has potent anti-inflammatory activities and may be useful to treat inflammatory disorders including RA and sepsis in humans. Disclosures: Balasubramanian: Pharmacyclics: Employment, Equity Ownership. Sirisawad:Pharmacyclics: Employment, Equity Ownership. Steggerda:Pharmacyclics: Employment, Equity Ownership. Cao:Pharmacyclics: Research Funding. Lowenstein:Pharmacyclics: Research Funding. Buggy:Pharmacyclics: Employment, Equity Ownership.

scholarly journals Downregulation of Inflammatory Cytokine Release from IL-1β and LPS-Stimulated PBMC Orchestrated by ST2825, a MyD88 Dimerisation Inhibitor

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4322
Author(s):  
Sergio Ramírez-Pérez ◽  
Luis Alexis Hernández-Palma ◽  
Edith Oregon-Romero ◽  
Brian Uriel Anaya-Macías ◽  
Samuel García-Arellano ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Inflammatory Cytokine ◽  
Mononuclear Cells ◽  
Cytokine Production ◽  
Primary Response ◽  
Peripheral Blood Mononuclear ◽  
Inflammatory Cytokine Production ◽  
Ifn Γ ◽  
Anti Inflammatory ◽  
Pathway Inhibition

The inflammatory process implicates homeostasis disruption and increased production of inflammatory mediators. Myeloid differentiation primary response 88 (MyD88) is an essential protein recruited after lipopolysaccharide (LPS) and interleukin (IL)-1β stimulation, a process that converges in nuclear factor kappa B (NF-κB) activation, as well as a transcription of several genes of both pro- and anti-inflammatory cytokines. The inhibition of MyD88 has shown efficacy by decrease inflammatory response, and has demonstrated potential application as a therapeutic target in chronic diseases. In this study, we investigate the effect of MyD88 dimerisation inhibitor ST2825 on cytokine production from rhIL-1β and LPS-stimulated peripheral blood mononuclear cells (PBMC) from healthy blood donors (HBD). ST2825 significantly downregulates the production of IFN-γ, IL-6, IL-12, IL-2, IL-15, IL-7, VEGF, IL-1Ra, IL-4, IL-5, IL-13 and IL-9 (p < 0.05) in LPS-stimulated PBMC. Moreover, ST2825 had a relatively low impact on IL-1β signalling pathway inhibition, showing that only a few specific cytokines, such as IFN-γ and IL-1Ra, are inhibited in rhIL-1β-stimulated PBMC (p < 0.01). In conclusion, MyD88 dimerisation inhibitor ST2825 showed high efficacy by inhibiting pro- and anti-inflammatory cytokine production in LPS-stimulated PBMC. Moreover, although rhIL-1β induced a sustained cytokine production (p < 0.05), ST2825 did not show a significant effect in the secretion of neither pro- nor anti-inflammatory cytokines in rhIL-1β-stimulated PBMC.

scholarly journals Cytoplasmic Interactions between the Glucocorticoid Receptor and HDAC2 Regulate Osteocalcin Expression in VPA-Treated MSCs

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 217 ◽  
Author(s):  
Marcella La Noce ◽  
Luigi Mele ◽  
Luigi Laino ◽  
Giovanni Iolascon ◽  
Gorizio Pieretti ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Hdac Inhibitor ◽  
Histone Deacetylases ◽  
Molecular Mechanisms ◽  
Severe Combined Immunodeficiency ◽  
Hdac Inhibitors ◽  
Stem Cell Differentiation ◽  
Mechanistic Explanation ◽  
Nonobese Diabetic

Epigenetic regulation has been considered an important mechanism for influencing stem cell differentiation. In particular, histone deacetylases (HDACs) have been shown to play a role in the osteoblast differentiation of mesenchymal stem cells (MSCs). In this study, the effect of the HDAC inhibitor, valproic acid (VPA), on bone formation in vivo by MSCs was determined. Surprisingly, VPA treatment, unlike other HDAC inhibitors, produced a well-organized lamellar bone tissue when MSCs–collagen sponge constructs were implanted subcutaneously into nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice, although a decrease of osteocalcin (OC) expression was observed. Consequently, we decided to investigate the molecular mechanisms by which VPA exerts such effects on MSCs. We identified the glucocorticoid receptor (GR) as being responsible for that downregulation, and suggested a correlation between GR and HDAC2 inhibition after VPA treatment, as evidenced by HDAC2 knockdown. Furthermore, using co-immunoprecipitation analysis, we showed for the first time in the cytoplasm, binding between GR and HDAC2. Additionally, chromatin immunoprecipitation (ChIP) assays confirmed the role of GR in OC downregulation, showing recruitment of GR to the nGRE element in the OC promoter. In conclusion, our results highlight the existence of a cross-talk between GR and HDAC2, providing a mechanistic explanation for the influence of the HDAC inhibitor (namely VPA) on osteogenic differentiation in MSCs. Our findings open new directions in targeted therapies, and offer new insights into the regulation of MSC fate determination.

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