A contraction assay system using established human bronchial smooth muscle cells

Role of miR-185-5p as modulator of periostin synthesis and smooth muscle contraction in asthma

Asthma is a chronic respiratory disease produced by an aberrant immune response that originates with breathing difficulties and cough, through airway remodeling. The above pathophysiological events of asthma emerge the regulators of effectors, like epigenetics, which include microRNAs (miRNAs) who perform post‐transcriptional regulation, controlling diverse pathways in respiratory diseases. The objective of the study was to determine how miR‐185‐5p regulates the secretion of periostin by airway structural cells, and smooth muscle cells contraction, both related to airway remodeling in asthma. We used miR‐185‐5p mimic and inhibitors in bronchial smooth muscle cells (BSMCs) and small airway epithelial cells (SAECs) from healthy subjects. Gene expression and protein levels of periostin (POSTN), CDC42, and RHOA were analyzed by RT‐PCR and ELISA/Western blot, respectively. BSMC contractility was analyzed using cell‐embedded collagen gels and measurement of intracellular calcium was performed using Fura‐2. Additionally, miR‐185‐5p and periostin expression were evaluated in sputum from healthy and asthmatics. From these experiments, we observed that miR‐185‐5p modulation regulates periostin mRNA and protein in BSMCs and SAECs. A tendency for diminished miR‐185‐5p expression and higher periostin levels was seen in sputum cells from asthmatics compared to healthy, with an inverse correlation observed between POSTN and miR‐185‐5p. Inhibition of miR‐185‐5p produced higher BSMCs contraction induced by histamine. Calcium mobilization was not modified by miR‐185‐5p, showing that miR‐185‐5p role in BSMC contractility is performed by regulating CDC42 and RhoA pro‐contractile factors instead. In conclusion, miR‐185‐5p is a modulator of periostin secretion by airway structural cells and of smooth muscle contraction, which can be related to asthma pathophysiology, and thus, might be a promising therapeutic target.

Epithelial expression and role of secreted STC1 on asthma airway hyperresponsiveness through calcium channel modulation

BACKGROUND

Asthma is characterized by airway hyperresponsiveness (AHR), inflammation, and airway remodeling. Airway hyperresponsiveness results from enhanced airway smooth muscle (ASM) contraction potentially under the control of an epithelium-derived relaxing factor (EpDRF). However, relatively rare is known about EpDRF. We aimed to elucidate the role of epithelium-derived stanniocalcin-1 (STC1) on AHR and ASM contraction.

METHODS

Stanniocalcin-1 levels in the serum of asthmatic patients and healthy volunteers and in bronchoalveolar lavage fluid (BALF) from ovalbumin (OVA)-challenged mice were measured by ELISA. The effects of exogenous STC1 on AHR and on inflammation were examined in mice. IL-13 modulation of STC1 mRNA and protein levels was studied in human bronchial epithelial cell lines (16HBE). The function of STC1 on Ca²⁺ influx and ASM contraction was examined ex vivo.

RESULTS

Serum STC1 was decreased in asthma (n = 93) compared with healthy volunteers (1071 ± 30.4 vs 1414 ± 75.1 pg/ml, p < 0.0001, n = 23) and correlated with asthma control (p = 0.0270), lung function (FEV1, p = 0.0130), and serum IL-13 levels (p = 0.0009). Treatment of ten asthmatic subjects with inhaled corticosteroids/long-acting beta2-agonists (ICS/LABA) for 1 year enhanced STC1 expression which correlated with improved asthma control (p = 0.022). STC1 was mainly expressed in bronchial epithelium and intranasal administration of recombinant human STC1 (rhSTC1) reduced AHR and inflammation in mice. IL-13 suppressed STC1 release from 16HBE, whereas rhSTC1 blocked store-operated Ca²⁺ entry (SOCE) by suppressing stromal interaction molecule 1 (STIM1) and further inhibited ASM cell contractility by suppressing Ca²⁺ -dependent myosin light chain (MLC) phosphorylation.

CONCLUSION

Our data indicate that STC1 deficiency in asthmatic airways promotes STIM1 hyperactivity, enhanced ASM contraction, and AHR. STC1 may be a candidate EpDRF.

Functional characterization of 3D contractile smooth muscle tissues generated using a unique microfluidic 3D bioprinting technology

Conditions such as asthma and inflammatory bowel disease are characterized by aberrant smooth muscle contraction. It has proven difficult to develop human cell-based models that mimic acute muscle contraction in 2D in vitro cultures due to the nonphysiological chemical and mechanical properties of lab plastics that do not allow for muscle cell contraction. To enhance the relevance of in vitro models for human disease, we describe how functional 3D smooth muscle tissue that exhibits physiological and pharmacologically relevant acute contraction and relaxation responses can be reproducibly fabricated using a unique microfluidic 3D bioprinting technology. Primary human airway and intestinal smooth muscle cells were printed into rings of muscle tissue at high density and viability. Printed tissues contracted to physiological concentrations of histamine (0.01-100 μM) and relaxed to salbutamol, a pharmacological compound used to relieve asthmatic exacerbations. The addition of TGFβ to airway muscle rings induced an increase in unstimulated muscle shortening and a decreased response to salbutamol, a phenomenon which also occurs in chronic lung diseases. Results indicate that the 3D bioprinted smooth muscle is a physiologically relevant in vitro model that can be utilized to study disease pathways and the effects of novel therapeutics on acute contraction and chronic tissue stenosis.

The therapeutic potential of histamine receptor ligands in inflammatory bowel disease

In the intestine of patients suffering from inflammatory bowel disease concentrations of histamine are increased compared to healthy controls. Genetic ablation of histamine production in mice ameliorates the course of experimentally induced colitis. These observations and first pharmacological studies indicate a function of histamine in the pathogenesis of inflammatory bowel disease. However, a closer examination reveals that available data are highly heterogeneous, limiting the rational design of strategies addressing specific histamine receptor subtypes as possible target for pharmacological interaction. However, very recently first clinical data indicate that antagonism at the histamine receptor subtype H4 provides a beneficial effect in at least the skin. Here, we discuss the available data on histamine effects and histamine receptor subtype functions in inflammatory bowel disease with a special emphasis on the histamine H4-receptor.

Development of vascular smooth muscle contractility by endothelium-derived transforming growth factor β proteins

It is well established that the release of vasodilators and vasoconstrictors from vascular endothelium regulates vascular smooth muscle contraction. In this report, we investigate the role of the endothelium in the development and maintenance of constitutive vascular contractility. For that purpose, contractile activity of cultured bovine aortic smooth muscle cells (BASMCs) embedded in collagen gels was monitored by changes in gel diameter. After culturing for 5 days, ATP- and high KCl solution-induced contractions were significantly enhanced in the gels that were overlaid with bovine aortic endothelial cells (BAECs) or were cultured with conditioned medium of cultured BAECs. ATP-induced Ca(2+) transients, recorded in BASMCs cultured with conditioned medium of BAECs, were markedly augmented, but high KCl-induced Ca(2+) transients were not affected. BASMCs in control gels were spindle shaped, and those in endothelium-treated gels were more elongated and interconnected. The endothelial conditioned medium also strongly affected the intracellular distribution of actin fibers. Conditioned medium of BAECs contained TGFβ1 and TGFβ2. The TGFβ receptor antagonist SB431542 as well as simultaneous treatment with TGFβ1 and TGFβ2 neutralizing antibodies completely reversed the above effects of endothelial conditioned medium on BASMCs. BAECs medium induced phosphorylation of Smad2 and increased ATP-induced phosphorylation of myosin light chain in BASMCs. The present results indicate that the release of TGFβ1 and TGFβ2 from vascular endothelium affects the contractility of vascular smooth muscle cells by altering their morphology and agonist-induced Ca(2+) mobilization.

A contraction assay system using primary cultured mouse bronchial smooth muscle cells

BACKGROUND

Contraction of bronchial smooth muscle is the main mechanism of asthmatic responses. Inflammatory cells such as eosinophils and mast cells produce chemical mediators that induce smooth muscle contraction. To investigate the mechanisms of IgE-independent asthmatic response in murine asthma models, a novel in vitro assay system using primary cultured mouse bronchial smooth muscle cells (BSMC) was explored.

METHOD

Trachea and bronchi were taken from young mice and underwent primary culture. BSMC were expanded in culture and then embedded in a collagen gel. The well-known constrictors leukotriene D4 (LTD4), methacholine and histamine were applied to the BSMC gels. The gel images were captured by an image analyzer and contractile responses were evaluated.

RESULTS

LTD4 and methacholine significantly induced the gel contraction in a dose-dependent manner, but histamine did not. Montelukast, a CysLT type ΙΙ receptor antagonist, and atropine, a muscarinic acetylcholine receptor antagonist, inhibited the contractile responses in an agonist-specific manner.

CONCLUSION

A contraction assay system using cultured mouse BSMC was successfully established for the first time. It may go a long way toward identifying bronchoconstricting mediators involved in murine asthma models.