Project description:Glucocorticoids are the cornerstone of asthma and other inflammatory disease therapy. Resistance or insensitivity to glucocorticoids presents a substantial and challenging clinical problem. MicroRNAs are emerging as central regulators of inflammation, but it is not clear whether they could augment or attenuate glucocorticoid responses. We aimed to identify microRNAs that regulate cytokine and chemokine expression in airway epithelial cells and whether these miRNAs are subject to the effects of glucocorticoids. MicroRNAomic analyses of primary bronchial epithelial cells and the A549 airway epithelial cell line identified 7 miRNAs that were altered by inflammatory cytokine treatment and 22 that were regulated by glucocorticoids (n=3 for each treatment). miR-146a emerged as a central candidate, whose expression was induced by TNF-alpha and repressed by glucocorticoids. Its role as a candidate in asthmatic inflammation was supported by expression profiling in human asthmatics, which showed that plasma miR-146a expression was elevated in asthma and associated with measures related to worse asthma outcomes, including elevated blood eosinophil counts, higher asthma control questionnaire scores, and need for higher doses of inhaled glucocorticoids. However, transfection of miR-146a in A549 cells treated with TNF-alpha +/- glucocorticoids produced an anti-inflammatory effect and with increased efficacy of glucocorticoids. We propose a model whereby miR-146a is induced by inflammatory conditions as a feedback mechanism to limit inflammation. Glucocorticoids may limit this regulatory pathway by preventing miR-146a expression. Consequently, exogenous administration of miR-146a could be a novel therapeutic strategy to enhance effects of glucocorticoids.
Project description:BackgroundMicroRNAs (miRNAs) are emerging as central regulators of inflammation, but their role in asthma and airway epithelial cells is not well studied. Glucocorticoids are the cornerstone of therapy in asthma and other inflammatory disease, yet their mechanisms of action are not completely elucidated, and it is not clear whether miRNAs modulate their effects.ObjectiveWe aimed to identify miRNAs that regulate cytokine and chemokine expression in airway epithelial cells and whether these miRNAs are subject to the effects of glucocorticoids.Methods and resultsMicroRNAomic analyses of immortalized, normal human bronchial epithelial cells identified 7 miRNAs that were altered by inflammatory cytokine treatment and 22 that were regulated by glucocorticoids (n = 3 for each treatment condition). MiR-146a emerged as a central candidate, whose expression was induced by TNF-? and repressed by glucocorticoids. Its role as a candidate in asthmatic inflammation was supported by expression profiling in human asthmatics, which showed that plasma miR-146a expression was elevated in asthma and associated with measures related to worse asthma outcomes, including elevated blood eosinophil counts, higher asthma control questionnaire scores, and need for higher doses of inhaled glucocorticoids. However, transfection of miR-146a in A549 cells treated with TNF-? +/- glucocorticoids produced an anti-inflammatory effect and increased efficacy of glucocorticoids.ConclusionsWe propose a model whereby miR-146a is induced by inflammatory conditions as a feedback mechanism to limit inflammation. Exogenous administration of miR-146a augmented the effects of glucocorticoids and could be a novel therapeutic strategy to enhance efficacy of these medications.
Project description:miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context.
Project description:This study addressed mechanisms through which glucocorticoids exert repressive effects on pro-inflammatory TNF signaling using Global Run-on Sequencing (GRO-seq) in Beas-2B airway epithelial cells treated with dexamethasone and/or TNF for 10 or 30 minutes.
Project description:This study was designed to explore the role of miRNA-146a (miR-146a) and its target genes in the endothelial cells. In this study we have demonstrated that lipopolysaccharide (LPS) induced upregulation of miR-146a in the human umbilical vein endothelial cells (HUVEC) and the induction was blocked by the silencing of the toll-like receptors (TLRs) adaptor molecules MyD88 and nonspecific NF-κB inhibitor BAY 11-7082. In addition, knockdown of miR-146a by transfection of the locked nucleic acid (LNA)-antimiR-146a significantly decreased the increased cell migration and tube formation induced by LPS. A combined analysis of the bioinformatics miRanda algorithms and the whole genome expression microarray of the immunoprecipitated Ago2 ribonucleoprotein complex identified 14 transcripts as the potential target genes. Subsequent transfection with miR-146a precursor pre-miR-146a into the HUVEC validated that the CARD10 was the target gene of the miR-146a both in the transcript and protein level.
Project description:Glucocorticoids, which activate glucocorticoid receptor signaling and thus modulate gene expression, are widely used to treat asthma. Glucocorticoids exert their therapeutic effects in part through modulating airway smooth muscle structure and function. However, the effects of genes that are regulated by GCs on airway function are not fully understood. Here, we used transcription profiling to characterize the effects of a potent glucocorticoid, dexamethasone, on cultured human airway smooth muscle gene expression at 4 and 24 hours.
Project description:Glucocorticoids, which activate glucocorticoid receptor signaling and thus modulate gene expression, are widely used to treat asthma. Glucocorticoids exert their therapeutic effects in part through modulating airway smooth muscle structure and function. However, the effects of genes that are regulated by GCs on airway function are not fully understood. Here, we used transcription profiling to characterize the effects of a potent glucocorticoid, dexamethasone, on cultured human airway smooth muscle gene expression at 4 and 24 hours. This study examined differential gene expression induced by treatment of cultured human airway smooth muscle cells with dexamethasone. There were 3 groups of samples and each group had 4 biological replicates. Group 1 was no treatment, Group 2 was dexamethasone (dex) treatment for 4 hours, Group 3 was dex treatment for 24 hours. Cultures were synchronized so harvest occurred at the same time for all three groups. 2 samples are not included in this analysis (based on unsupervised clustering of samples and diagnostic plots).
Project description:miR-146a is a known anti-inflammatory miRNA. Intringuigly, it is overexpressed in RAS-induced senescent cells which is accompanied with a rich pro-inflammatoy secretpry phenotype. We aim to study possible sponges for miR-146a.
Project description:Expression data from airway brush biopsy samples, differentiated primary cultures of human airway epithelia, CaLu3 cultures at the air liquid interface, and primary cultures of human airway epithelia submerged in nutrient media Organotypic cultures of primary human airway epithelial cells have been used to investigate the morphology, ion and fluid transport, innate immunity, transcytosis, infection, inflammation, signaling, cilia and repair functions of this complex tissue. However, we do not know how close these cultures resemble the epithelia in vivo. In this study, we examine the genome-wide expression profile of human airway epithelial cells in vivo obtained from brush biopsies of the trachea and bronchus of healthy volunteers and compare it to the expression profile of primary cultures of human airway epithelia grown at the air-liquid interface. For comparison we also investigate the expression profile of Calu3 cells grown at the air-liquid interface and primary cultures of human airway epithelia submerged in nutrient media. We compare the transcriptional profile of human in vivo airway epithelia from trachea and bronchus to differentiated primary human airway epithelia cultures, also from trachea and bronchus, and grown at the air-liquid interface. We also included the profile of Calu3 cultures grown at the air-liquid interface and primary cultures submerged in nutrient media.
Project description:MiR-146a is an important regulator of innate inflammatory responses and is also implicated in cell death and survival. Here, we identified microglia as the main cellular source of miR-146a among mouse CNS resident cells. We further characterized the phenotype of miR-146a KO microglia cells during in vivo demyelination induced by cuprizone (CPZ) and found reduced number of CD11c+ microglia in the KO compared to WT mice. Microglia were also isolated from the brain, and the proteome was analyzed by liquid chromatography mass spectrometry.