The modulation of platelet function by growth hormone in growth hormone deficient Hypopituitary patients.

BACKGROUND: Growth hormone deficiency (GHD) has been implicated in increased cardiovascular and cerebrovascular disease risk seen in hypopituitarism, however the mechanism remains speculative. We hypothesise that platelet abnormalities may play a contributory role. Herein we examined platelet behaviour in GHD hypopituitary patients, pre- and post-growth hormone (GH) replacement. METHODS: This study utilizes a physiological flow-based assay to quantify platelet function in whole blood from patient cohorts under arterial shear. Thirteen GH Naïve hypopituitary adults with GHD and thirteen healthy matched controls were studied. Patients were assessed before and after GH treatment. All other pituitary replacements were optimised before the study. In addition to a full endocrine profile, whole blood was labelled and perfused over immobilised von Willibrand factor (vWF). Seven parameters of dynamic platelet-vWF interactions were recorded using digital image microscopy and analysed by customised platelet tracking software. RESULTS: We found a significantly altered profile of platelet-vWF interactions in GHD individuals compared to healthy controls. Specifically, we observed a marked increase in platelets shown to form associations such as tethering, rolling and adherence to immobilized vWF, which were reduced post GH treatment. Speed and distance platelets travelled across vWF was similar between controls and pre-therapy GHD patients, however, this was considerably increased post treatment. This may indicate reduced platelet signaling resulting in less stable adhesion of platelets post GH treatment. CONCLUSIONS: Taken together observed differences in platelet behaviour may contribute to an increased risk of thrombosis in GHD which can in part be reversed by GH therapy.

Precise Targeting of miRNA Sites Restores CFTR Activity in CF Bronchial Epithelial Cells.

MicroRNAs that are overexpressed in cystic fibrosis (CF) bronchial epithelial cells (BEC) negatively regulate CFTR and nullify the beneficial effects of CFTR modulators. We hypothesized that it is possible to reverse microRNA-mediated inhibition of CFTR using CFTR-specific target site blockers (TSBs) and to develop a drug-device combination inhalation therapy for CF. Lead microRNA expression was quantified in a series of human CF and non-CF samples and in vitro models. A panel of CFTR 3' untranslated region (UTR)-specific locked nucleic acid antisense oligonucleotide TSBs was assessed for their ability to increase CFTR expression. Their effects on CFTR activity alone or in combination with CFTR modulators were measured in CF BEC models. TSB encapsulation in poly-lactic-co-glycolic acid (PLGA) nanoparticles was assessed as a proof of principle of delivery into CF BECs. TSBs targeting the CFTR 3' UTR 298-305:miR-145-5p or 166-173:miR-223-3p sites increased CFTR expression and anion channel activity and enhanced the effects of ivacaftor/lumacaftor or ivacaftor/tezacaftor in CF BECs. Biocompatible PLGA-TSB nanoparticles promoted CFTR expression in primary BECs and retained desirable biophysical characteristics following nebulization. Alone or in combination with CFTR modulators, aerosolized CFTR-targeting TSBs encapsulated in PLGA nanoparticles could represent a promising drug-device combination therapy for the treatment for CFTR dysfunction in the lung.

MiRNA Expression in Cystic Fibrosis Bronchial Epithelial Cells.

Bronchial epithelial cells represent an invaluable tool to elucidate molecular signaling regulation in cystic fibrosis (CF). CF is a lethal genetic condition characterized by chronic inflammation in which bronchial epithelial cells play a pivotal role. Here we describe their use in analysis of microRNA (miRNA) and their target genes following a two-step RT-PCR miRNA profiling method in bronchial cell specimens from CF and control individuals where 667 human miRNA were examined. We also describe an approach to experimental modulation of these miRNA in vitro.

miRNA-221 is elevated in cystic fibrosis airway epithelial cells and regulates expression of ATF6.

BACKGROUND: MicroRNA (miRNA) and messenger RNA (mRNA) expression differs in cystic fibrosis (CF) versus non-CF bronchial epithelium. Here, the role of miRNA in basal regulation of the transcription factor ATF6 was investigated in bronchial epithelial cells in vitro and in vivo. METHODS: Using in silico analysis, miRNAs predicted to target the 3'untranslated region (3'UTR) of the human ATF6 mRNA were identified. RESULTS: Three of these miRNAs, miR-145, miR-221 and miR-494, were upregulated in F508del-CFTR homozygous CFBE41o- versus non-CF 16HBE14o- bronchial epithelial cells and also in F508del-CFTR homozygous or heterozygous CF (n = 8) versus non-CF (n = 9) bronchial brushings. ATF6 was experimentally validated as a molecular target of these miRNAs through the use of a luciferase reporter vector containing the full-length 3'UTR of ATF6. Expression of ATF6 was observed to be decreased in CF both in vivo and in vitro. miR-221 was also predicted to regulate murine ATF6, and its expression was significantly increased in native airway tissues of 6-week-old ßENaC-overexpressing transgenic mice with CF-like lung disease versus wild-type littermates. CONCLUSIONS: These results implicate miR-145, miR-221 and miR-494 in the regulation of ATF6 in CF bronchial epithelium, with miR-221 demonstrating structural and functional conservation between humans and mice. The altered miRNA expression evident in CF bronchial epithelial cells can affect expression of transcriptional regulators such as ATF6.

miR-17 overexpression in cystic fibrosis airway epithelial cells decreases interleukin-8 production.

Interleukin (IL)-8 levels are higher than normal in cystic fibrosis (CF) airways, causing neutrophil infiltration and non-resolving inflammation. Overexpression of microRNAs that target IL-8 expression in airway epithelial cells may represent a therapeutic strategy for cystic fibrosis. IL-8 protein and mRNA were measured in cystic fibrosis and non-cystic fibrosis bronchoalveolar lavage fluid and bronchial brushings (n=20 per group). miRNAs decreased in the cystic fibrosis lung and predicted to target IL-8 mRNA were quantified in ßENaC-transgenic, cystic fibrosis transmembrane conductance regulator (Cftr)-/- and wild-type mice, primary cystic fibrosis and non-cystic fibrosis bronchial epithelial cells and a range of cystic fibrosis versus non-cystic fibrosis airway epithelial cell lines or cells stimulated with lipopolysaccharide, Pseudomonas-conditioned medium or cystic fibrosis bronchoalveolar lavage fluid. The effect of miRNA overexpression on IL-8 protein production was measured. miR-17 regulates IL-8 and its expression was decreased in adult cystic fibrosis bronchial brushings, ßENaC-transgenic mice and bronchial epithelial cells chronically stimulated with Pseudomonas-conditioned medium. Overexpression of miR-17 inhibited basal and agonist-induced IL-8 protein production in F508del-CFTR homozygous CFTE29o(-) tracheal, CFBE41o(-) and/or IB3 bronchial epithelial cells. These results implicate defective CFTR, inflammation, neutrophilia and mucus overproduction in regulation of miR-17. Modulating miR-17 expression in cystic fibrosis bronchial epithelial cells may be a novel anti-inflammatory strategy for cystic fibrosis and other chronic inflammatory airway diseases.

miR-31 dysregulation in cystic fibrosis airways contributes to increased pulmonary cathepsin S production.

RATIONALE: Cathepsin S (CTSS) activity is increased in bronchoalveolar lavage (BAL) fluid from patients with cystic fibrosis (CF). This activity contributes to lung inflammation via degradation of antimicrobial proteins, such as lactoferrin and members of the ß-defensin family. OBJECTIVES: In this study, we investigated the hypothesis that airway epithelial cells are a source of CTSS, and mechanisms underlying CTSS expression in the CF lung. METHODS: Protease activity was determined using fluorogenic activity assays. Protein and mRNA expression were analyzed by ELISA, Western blotting, and reverse-transcriptase polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: In contrast to neutrophil elastase, CTSS activity was detectable in 100% of CF BAL fluid samples from patients without Pseudomonas aeruginosa infection. In this study, we identified epithelial cells as a source of pulmonary CTSS activity with the demonstration that CF airway epithelial cells express and secrete significantly more CTSS than non-CF control cells in the absence of proinflammatory stimulation. Furthermore, levels of the transcription factor IRF-1 correlated with increased levels of its target gene CTSS. We discovered that miR-31, which is decreased in the CF airways, regulates IRF-1 in CF epithelial cells. Treating CF bronchial epithelial cells with a miR-31 mimic decreased IRF-1 protein levels with concomitant knockdown of CTSS expression and secretion. CONCLUSIONS: The miR-31/IRF-1/CTSS pathway may play a functional role in the pathogenesis of CF lung disease and may open up new avenues for exploration in the search for an effective therapeutic target.

Regulation of cystic fibrosis transmembrane conductance regulator by microRNA-145, -223, and -494 is altered in ΔF508 cystic fibrosis airway epithelium.

Expression of the cystic fibrosis transmembrane conductance regulator (CFTR) is altered in individuals with the ΔF508 CFTR mutation. We previously reported differential expression of microRNA (miRNA) in CF airway epithelium; however, the role of miRNA in regulation of CFTR expression here remains unexplored. In this study, we investigated the role of upregulated miRNAs in CFTR regulation in vivo in bronchial brushings from individuals homozygous or heterozygous for ΔF508 CFTR, validated our observations in vitro, and assessed the impact of defective chloride ion conductance, genotype, and colonization status on miRNA expression. miRNA target prediction was performed in silico, and expression of miRNA and target genes were measured by quantitative real-time PCR and/or Western blotting. Overexpression and inhibition studies were performed with pre-miRs or antimiRs, respectively, and a luciferase reporter gene was used to elucidate direct miRNA-target interactions. miR-145, miR-223, and miR-494 were upregulated in CF versus non-CF bronchial brushings and cell lines; in ΔF508 CFTR homozygotes versus heterozygotes; in subjects positive for P. aeruginosa; and in cells treated with a CFTR inhibitor or IL-1ß. Reciprocal downregulation or upregulation of CFTR gene and/or protein expression was observed after miRNA manipulation and direct miRNA-target relationships demonstrated via a reporter system containing a wild type or mutated full-length CFTR 3' untranslated region. Increased expression of miR-145, miR-223, and miR-494 in vivo in bronchial epithelium of individuals carrying the ΔF508 CFTR mutation correlates with decreased CFTR expression. Defective CFTR function, Pseudomonas colonization, and inflammation may affect miRNA expression and contribute to the regulation of ΔF508 CFTR.

MicroRNAs in inflammatory lung disease--master regulators or target practice?

MicroRNAs (miRNAs) have emerged as a class of regulatory RNAs with immense significance in numerous biological processes. When aberrantly expressed miRNAs have been shown to play a role in the pathogenesis of several disease states. Extensive research has explored miRNA involvement in the development and fate of immune cells and in both the innate and adaptive immune responses whereby strong evidence links miRNA expression to signalling pathways and receptors with critical roles in the inflammatory response such as NF-κB and the toll-like receptors, respectively. Recent studies have revealed that unique miRNA expression profiles exist in inflammatory lung diseases such as cystic fibrosis, chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis and lung cancer. Evaluation of the global expression of miRNAs provides a unique opportunity to identify important target gene sets regulating susceptibility and response to infection and treatment, and control of inflammation in chronic airway disorders. Over 800 human miRNAs have been discovered to date, however the biological function of the majority remains to be uncovered. Understanding the role that miRNAs play in the modulation of gene expression leading to sustained chronic pulmonary inflammation is important for the development of new therapies which focus on prevention of disease progression rather than symptom relief. Here we discuss the current understanding of miRNA involvement in innate immunity, specifically in LPS/TLR4 signalling and in the progression of the chronic inflammatory lung diseases cystic fibrosis, COPD and asthma. miRNA in lung cancer and IPF are also reviewed.

17Beta-estradiol inhibits IL-8 in cystic fibrosis by up-regulating secretory leucoprotease inhibitor.

RATIONALE: An unexplained gender gap is observed in cystic fibrosis (CF). Females have poorer lung function, decreased survival, and earlier Pseudomonas colonization. OBJECTIVES: To evaluate the effect of 17beta-estradiol (E(2)) on CF bronchial epithelial cells in vitro and in vivo. METHODS: On exposure of CFBE41o- cultures to physiological concentrations of E(2), there was a significant dose-dependent inhibition of IL-8 release induced by toll-like receptor agonists, CF bronchoalveolar lavage fluid, or Pseudomonas-conditioned media. Estrogen receptor (ER)-alpha and -beta expression was quantified in cell lines and bronchial brushings from CF and non-CF patients. MEASUREMENTS AND MAIN RESULTS: Both receptors were expressed in vitro and in vivo, although ERbeta expression was significantly higher in CF. Using ER isoform-specific agonists and antagonists, we established that ERbeta mediates the inhibition of CF bronchoalveolar lavage fluid-induced IL-8 release. We also showed that secretory leucoprotease inhibitor gene expression and protein localization to the nucleus increased in response to E(2). Secretory leucoprotease inhibitor knockdown abrogated the inhibitory effects of E(2). CONCLUSIONS: E(2) inhibits IL-8 release by ERbeta in CF bronchial epithelial cells through up-regulation of secretory leucoprotease inhibitor, inhibition of nuclear factor (NF)-kappaB, and IL-8 gene expression. These data implicate a novel anti-inflammatory mechanism for E(2) in females with CF, which predisposes to infection and colonization. This could, in part, account for the observed gender dichotomy in CF.

miR-126 is downregulated in cystic fibrosis airway epithelial cells and regulates TOM1 expression.

Cystic fibrosis (CF) is one of the most common lethal genetic diseases in which the role of microRNAs has yet to be explored. Predicted to be regulated by miR-126, TOM1 (target of Myb1) has been shown to interact with Toll-interacting protein, forming a complex to regulate endosomal trafficking of ubiquitinated proteins. TOM1 has also been proposed as a negative regulator of IL-1beta and TNF-alpha-induced signaling pathways. MiR-126 is highly expressed in the lung, and we now show for the first time differential expression of miR-126 in CF versus non-CF airway epithelial cells both in vitro and in vivo. MiR-126 downregulation in CF bronchial epithelial cells correlated with a significant upregulation of TOM1 mRNA, both in vitro and in vivo when compared with their non-CF counterparts. Introduction of synthetic pre-miR-126 inhibited luciferase activity in a reporter system containing the full length 3'-untranslated region of TOM1 and resulted in decreased TOM1 protein production in CF bronchial epithelial cells. Following stimulation with LPS or IL-1beta, overexpression of TOM1 was found to downregulate NF-kappaB luciferase activity. Conversely, TOM1 knockdown resulted in a significant increase in NF-kappaB regulated IL-8 secretion. These data show that miR-126 is differentially regulated in CF versus non-CF airway epithelial cells and that TOM1 is a miR-126 target that may have an important role in regulating innate immune responses in the CF lung. To our knowledge, this study is the first to report of a role for TOM1 in the TLR2/4 signaling pathways and the first to describe microRNA involvement in CF.