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Hawkins R.D.,University of California at San Diego | Hon G.C.,University of California at San Diego | Yang C.,Morgridge Institute for Research | Antosiewicz-Bourget J.E.,University of Wisconsin - Madison | And 15 more authors.
Cell Research | Year: 2011

Pluripotency, the ability of a cell to differentiate and give rise to all embryonic lineages, defines a small number of mammalian cell types such as embryonic stem (ES) cells. While it has been generally held that pluripotency is the product of a transcriptional regulatory network that activates and maintains the expression of key stem cell genes, accumulating evidence is pointing to a critical role for epigenetic processes in establishing and safeguarding the pluripotency of ES cells, as well as maintaining the identity of differentiated cell types. In order to better understand the role of epigenetic mechanisms in pluripotency, we have examined the dynamics of chromatin modifications genome-wide in human ES cells (hESCs) undergoing differentiation into a mesendodermal lineage. We found that chromatin modifications at promoters remain largely invariant during differentiation, except at a small number of promoters where a dynamic switch between acetylation and methylation at H3K27 marks the transition between activation and silencing of gene expression, suggesting a hierarchy in cell fate commitment over most differentially expressed genes. We also mapped over 50 000 potential enhancers, and observed much greater dynamics in chromatin modifications, especially H3K4me1 and H3K27ac, which correlate with expression of their potential target genes. Further analysis of these enhancers revealed potentially key transcriptional regulators of pluripotency and a chromatin signature indicative of a poised state that may confer developmental competence in hESCs. Our results provide new evidence supporting the role of chromatin modifications in defining enhancers and pluripotency. © 2011 IBCB, SIBS, CAS All rights reserved. Source


Xie Y.,University of Maryland Baltimore County | Akpinarli A.,National Institutes of Allergy and Infectious Disease | Maris C.,Johns Hopkins University | Hipkiss E.L.,Johns Hopkins University | And 6 more authors.
Journal of Experimental Medicine | Year: 2010

In vitro differentiated CD8+ T cells have been the primary focus of immunotherapy of cancer with little focus on CD4+ T cells. Immunotherapy involving in vitro differentiated T cells given after lymphodepleting regimens significantly augments antitumor immunity in animals and human patients with cancer. However, the mechanisms by which lymphopenia augments adoptive cell therapy and the means of properly differentiating T cells in vitro are still emerging. We demonstrate that naive tumor/self-specific CD4+ T cells naturally differentiated into T helper type 1 cytotoxic T cells in vivo and caused the regression of established tumors and depigmentation in lymphopenic hosts. Therapy was independent of vaccination, exogenous cytokine support, CD8+, B, natural killer (NK), and NKT cells. Proper activation of CD4+ T cells in vivo was important for tumor clearance, as naive tumor-specific CD4+ T cells could not completely treat tumor in lymphopenic common gamma chain (γc)-deficient hosts. γc signaling in the tumor-bearing host was important for survival and proper differentiation of adoptively transferred tumor-specific CD4 + T cells. Thus, these data provide a platform for designing immunotherapies that incorporate tumor/self-reactive CD4+ T cells. © 2010 Xie et al. Source


Kubler A.,Imperial College London | Kubler A.,Johns Hopkins University | Luna B.,Johns Hopkins University | Larsson C.,Umea University | And 26 more authors.
Journal of Pathology | Year: 2015

Active tuberculosis (TB) often presents with advanced pulmonary disease, including irreversible lung damage and cavities. Cavitary pathology contributes to antibiotic failure, transmission, morbidity and mortality. Matrix metalloproteinases (MMPs), in particular MMP-1, are implicated in TB pathogenesis. We explored the mechanisms relating MMP/TIMP imbalance to cavity formation in a modified rabbit model of cavitary TB. Our model resulted in consistent progression of consolidation to human-like cavities (100% by day 28), with resultant bacillary burdens (>107 CFU/g) far greater than those found in matched granulomatous tissue (105 CFU/g). Using a novel, breath-hold computed tomography (CT) scanning and image analysis protocol, we showed that cavities developed rapidly from areas of densely consolidated tissue. Radiological change correlated with a decrease in functional lung tissue, as estimated by changes in lung density during controlled pulmonary expansion (R2 = 0.6356, p < 0.0001). We demonstrated that the expression of interstitial collagenase (MMP-1) was specifically greater in cavitary compared to granulomatous lesions (p < 0.01), and that TIMP-3 significantly decreased at the cavity surface. Our findings demonstrated that an MMP-1/TIMP imbalance is associated with the progression of consolidated regions to cavities containing very high bacterial burdens. Our model provided mechanistic insight, correlating with human disease at the pathological, microbiological and molecular levels. It also provided a strategy to investigate therapeutics in the context of complex TB pathology. We used these findings to predict a MMP/TIMP balance in active TB and confirmed this in human plasma, revealing the potential of MMP/TIMP levels as key components of a diagnostic matrix aimed at distinguishing active from latent TB (PPV = 92.9%, 95% CI 66.1-99.8%, NPV = 85.6%; 95% CI 77.0-91.9%). © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Source


Lobanenkov V.,National Institutes of Allergy and Infectious Disease | Loukinov D.,National Institutes of Allergy and Infectious Disease | Pugacheva E.,National Institutes of Allergy and Infectious Disease
Epigenomics | Year: 2011

The main objective of this conference was to provide solid evidence that environmental exposures during early development can affect faithful reproduction of individual parental epigenomes without changing DNA sequence in the offspring. No doubt, this important goal has been successfully achieved owing to the high quality of presented epidemiological and experimental studies and engaging discussions of many yet to be published results. Compelling data suggested a strong causal link between prenatal vulnerability of future parental epigenomes to damaging environmental factors aggravated by abnormal socio-cultural conditions (including, for instance, malnutrition and chronic stress) and the alarming risk of developing heritable complex medical conditions later in life, such as asthma, autism, cancer, cardiovascular disease, diabetes, obesity, schizophrenia and a whole range of rare neuromuscular pathologies. It was concluded that modern epigenetic research promises to markedly improve our ability to diagnose, prevent and treat these and other pathological conditions of humans. However, the complex heritability pattern of epigenetic syndromes also introduces unique legal and ethical issues that were discussed at the end of this outstanding meeting. © 2011 Future Medicine Ltd. Source


Kelada S.,University of North Carolina at Chapel Hill | Sethupathy P.,University of North Carolina at Chapel Hill | Okoye I.S.,UK National Institute for Medical Research | Kistasis E.,UK National Institute for Medical Research | And 11 more authors.
PLoS Pathogens | Year: 2013

A diverse suite of effector immune responses provide protection against various pathogens. However, the array of effector responses must be immunologically regulated to limit pathogen- and immune-associated damage. CD4+Foxp3+ regulatory T cells (Treg) calibrate immune responses; however, how Treg cells adapt to control different effector responses is unclear. To investigate the molecular mechanism of Treg diversity we used whole genome expression profiling and next generation small RNA sequencing of Treg cells isolated from type-1 or type-2 inflamed tissue following Leishmania major or Schistosoma mansoni infection, respectively. In-silico analyses identified two miRNA "regulatory hubs" miR-10a and miR-182 as critical miRNAs in Th1- or Th2-associated Treg cells, respectively. Functionally and mechanistically, in-vitro and in-vivo systems identified that an IL-12/IFNγ axis regulated miR-10a and its putative transcription factor, Creb. Importantly, reduced miR-10a in Th1-associated Treg cells was critical for Treg function and controlled a suite of genes preventing IFNγ production. In contrast, IL-4 regulated miR-182 and cMaf in Th2-associed Treg cells, which mitigated IL-2 secretion, in part through repression of IL2-promoting genes. Together, this study indicates that CD4+Foxp3+ cells can be shaped by local environmental factors, which orchestrate distinct miRNA pathways preserving Treg stability and suppressor function. Source

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