Emerging airway smooth muscle targets to treat asthma

The Impact of Monoclonal Antibodies on Airway Smooth Muscle Contractility in Asthma: A Systematic Review

Airway hyperresponsiveness (AHR) represents a central pathophysiological hallmark of asthma, with airway smooth muscle (ASM) being the effector tissue implicated in the onset of AHR. ASM also exerts pro-inflammatory and immunomodulatory actions, by secreting a wide range of cytokines and chemokines. In asthma pathogenesis, the overexpression of several type 2 inflammatory mediators including IgE, IL-4, IL-5, IL-13, and TSLP has been associated with ASM hyperreactivity, all of which can be targeted by humanized monoclonal antibodies (mAbs). Therefore, the aim of this review was to systematically assess evidence across the literature on mAbs for the treatment of asthma with respect to their impact on the ASM contractile tone. Omalizumab, mepolizumab, benralizumab, dupilumab, and tezepelumab were found to be effective in modulating the contractility of the ASM and preventing the AHR, but no available studies concerning the impact of reslizumab on the ASM were identified from the literature search. Omalizumab, dupilumab, and tezepelumab can directly modulate the ASM in asthma, by specifically blocking the interaction between IgE, IL-4, and TSLP, and their receptors are located on the surface of ASM cells. Conversely, mepolizumab and benralizumab have prevalently indirect impacts against AHR by targeting eosinophils and other immunomodulatory effector cells promoting inflammatory processes. AHR has been suggested as the main treatable trait towards precision medicine in patients suffering from eosinophilic asthma, therefore, well-designed head-to-head trials are needed to compare the efficacy of those mAbs that directly target ASM contractility specifically against the AHR in severe asthma, namely omalizumab, dupilumab, and tezepelumab.

The Action of Shenmai Injection on the Inflammation and Proliferation of Smooth Muscle Cells of the Airway in Asthmatic Rats

To observe the effect of transient receptor potential ankyrin 1 (TRPA1) channel on the proliferation and inflammation of airway smooth muscle cells (SMC) in asthmatic rats, the rats were randomly allocated into three treatment groups: control, asthma, and Shenmai injection (SMI), with 15 rats in each group. Asthmatic rat models were induced by ovalbumin (OVA) inhalation. Rats in the control and asthma groups were intraperitoneally injected 2 mL NS daily, whereas rats in the SMI treatment group were intraperitoneally injected with 2 mL SMI daily. RT-qPCR and western blotting were used to test for TRPA1 and proliferating cell nuclear antigen (PCNA) mRNA and protein expression. ELISA was used to test the expression of interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13) in the serum. Compared with the control group, there were significantly higher levels of TRPA1 and PCNA mRNA and protein, as well as of IL-4, IL-5, and IL-13 in asthmatic rats (P< 0.05). After SMI treatment, there was significantly lower expression of TRPA1, PCNA, IL-4, IL-5, and IL-13 compared to the levels in asthmatic rats (P < 0.05). TRPA1, IL-4, IL-5, and IL-13 were highly expressed in the tracheal SMC of asthmatic rats. Inhibiting TRPA1, IL-4, IL-5, and IL-13 using SMI may be one of the mechanisms that can intervene chronic airway inflammation and asthma proliferation.

Research progress in the mechanism of calcium ion on contraction and relaxation of airway smooth muscle cells

lntracellular calcium ion is the key secondary messenger system of the cellular processes in airway smooth muscle cells(ASMc). The treatment and regulation of Ca²⁺ in airway smooth muscle (ASM) is, in part, to associated with many airway diseases such as asthma, COPD and pulmonary fibrosis. The mechanism of contraction and relaxation of ASM is a concerned aspect in airway diseases. This review emphasizes established and recent discoveries whice show the research progress of Ca²⁺ on cell contraction and relaxation in ASM in recent years, to provide theoretical support and new targets for clinical prevention and treatment of perioperative bronchospasm and variousrespiratory related diseases.

Preformulation and Evaluation of Tofacitinib as a Therapeutic Treatment for Asthma

Preformulation studies on tofacitinib citrate, a small molecule JAK3 specific inhibitor, have not been previously reported in literature. We therefore conducted several preformulation studies on tofacitinib citrate, and its free base, to better understand factors that affect its solubility, stability, and solid-state characteristics. Further, the results of the preformulation studies helped facilitate the development of a nebulized formulation of tofacitinib citrate for inhalational delivery to house dust mite allergen-challenged, BALB/c mice as a potential treatment for eosinophilic asthma. The preformulation results indicated tofacitinib having a basic pKa of 5.2, with its stability dependent on pH, ionic strength, and temperature. Degradation of tofacitinib follows apparent first-order kinetics. In order to maximize stability of the drug, ionic strength and temperature should be minimized, with an optimal range pH between 2.0 and 5.0. Additionally, our findings demonstrate that tofacitinib citrate can successfully be nebulized at a suitable droplet size for inhalation (1.2 ± 0.2 μm MMAD) through a nose-only chamber. Animals dosed with tofacitinib citrate demonstrated marked reductions in BAL eosinophils and total protein concentrations following HDM challenge. These data suggest that tofacitinib citrate represents the potential to be an effective therapy for eosinophilic asthma.

Inhibition of H3K27me3 demethylases attenuates asthma by reversing the shift in airway smooth muscle phenotype

BACKGROUND

The shift in airway smooth muscle cells (ASMCs) phenotype between proliferation and contraction during asthma has been reported recently, highlighting a role of ASMCs plasticity in the pathophysiology of asthma. As an event involved in epigenetic post-translational modification, histone H3 lysine27 (H3K27) demethylation has attracted significant attention with respect to the epigenetic changes in diverse cells; however, little is known about its contribution to the switching of ASMCs phenotype in asthma.

OBJECTIVE

To investigate the role of trimethylated H3K27 (H3k27me3) demethylation in ASM remodelling as well as the underling mechanism.

METHODS

Mice were exposed five times a week to house dust mite (HDM) extract for 5 weeks. Lung function was measured following the final HDM challenge. Airway inflammation and remodelling were then assessed in lungs of individual mice. Human ASMCs were purchased from Sciencell Research Laboratories. Proliferation, synthesis, migration and contraction of ASMCs were analysed, respectively.

RESULTS

We observed demethylation at H3k27me3 sites in lungs harvested from mice exposed to HDM extract. Administration of a selective inhibitor of H3K27 demethylase (GSK-J4) could ameliorate the classical hallmarks of asthma, such as airway hyperresponsiveness, airway inflammation and remodelling. We established a proliferative as well as a contractive model of human ASMCs to explore the impacts of H3K27 demethylase inhibition on ASMCs phenotype. Our results indicated that GSK-J4 decreased ASMCs proliferation and migration elicited by PDGF through the Akt/JNK signalling; GSK-J4 also prevented the upregulation of contractile proteins in ASMCs induced by TGF-β through the Smad3 pathway.

CONCLUSIONS

Inhibition of H3K27me3 demethylation alleviated the development of asthmatic airway disease in vivo and modulated ASMCs phenotype in vitro. Collectively, our findings highlight a role of H3K27me3 demethylation in experimental asthma and ASMCs phenotype switch.

Heat Shock-Related Protein 20 Peptide Decreases Human Airway Constriction Downstream of β2-Adrenergic Receptor

Severe bronchospasm refractory to β-agonists is a challenging aspect of asthma therapy, and novel therapeutics are needed. β-agonist-induced airway smooth muscle (ASM) relaxation is associated with increases in the phosphorylation of the small heat shock-related protein (HSP) 20. We hypothesized that a transducible phosphopeptide mimetic of HSP20 (P20 peptide) causes relaxation of human ASM (HASM) by interacting with target(s) downstream of the β2-adrenergic receptor (β2AR) pathway. The effect of the P20 peptide on ASM contractility was determined in human and porcine ASM using a muscle bath. The effect of the P20 peptide on filamentous actin dynamics and migration was examined in intact porcine ASM and cultured primary HASM cells. The efficacy of the P20 peptide in vivo on airway hyperresponsiveness (AHR) was determined in an ovalbumin (OVA) sensitization and challenge murine model of allergic airway inflammation. P20 peptide caused dose-dependent relaxation of carbachol-precontracted ASM and blocked carbachol-induced contraction. The β2AR inhibitor, (±)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride (ICI 118,551), abrogated isoproterenol but not P20 peptide-mediated relaxation. The P20 peptide decreased filamentous actin levels in intact ASM, disrupted stress fibers, and inhibited platelet-derived growth factor-induced migration of HASM cells. The P20 peptide treatment reduced methacholine-induced AHR in OVA mice without affecting the inflammatory response. These results suggest that the P20 peptide decreased airway constriction and disrupted stress fibers through regulation of the actin cytoskeleton downstream of β2AR. Thus, the P20 peptide may be a potential therapeutic for asthma refractory to β-agonists.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels

Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.

Suppression of the increasing level of acetylcholine-stimulated intracellular Ca2+ in guinea pig airway smooth muscle cells by mabuterol

The present study aimed to establish an effective method for the in vitro culture of guinea pig airway smooth muscle (ASM) cells, and also investigate the suppressive effect of mabuterol hydrochloride (Mab) on the increased level of intracellular Ca²⁺ in ASM cells induced with acetylcholine (Ach). Two different methods, i.e. with or without collagenase to pretreat tracheal tissues, were applied to the manufacture of ASM cells. Cell viability was determined with the 3-(4,5-dimethylthinazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Immunocytochemistry and immunofluorescence were used for the identification of ASM cells. Different concentration levels (10^-3, 10^-4, 10^-5, 10^-6 and 10^-7 mmol/l) of Mab were administered 5 min before Ach (10^-4 M) treatment, respectively. The Ca²⁺ fluorescent probe, Fura-2/AM or Fluo-3/AM were applied to the inspection of Ca²⁺ fluorescent intensity with Varioskan Flash, immunocytometry systems and an inverted system microscope, respectively. The results showed that the fresh method, in which isolated tracheal tissues were previously treated with collagenase for 20 min, was more advantageous for the preparation of guinea pig ASM cells compared to when the enzyme was not used. The time for the ASM cells to initially migrate out of the 'tissue blocks' and the culture having to be generated due to the thick cell density was significantly less. On identification with immunocytochemistry or immunofluorescent staining, >95% of the cells were ASM cells. Mab (10^-3-10^-7 mmol/l) significantly suppressed the elevation of intracellular Ca²⁺ induced by Ach in a concentration-dependent manner. The inhibitory rates of intracellular Ca²⁺ by different concentrations of Mab, from low to high, were 14.93, 24.73, 40.06, 48.54 and 57.13%, respectively, when Varioskan Flash was used for determination. In conclusion, this novel method has a shorter harvesting period for ASM cells. Mab can suppress the increasing level of intracellular Ca²⁺ induced by Ach in guinea pig ASM cells. Further investigation into the precise mechanisms of action is required.

Computed tomography assessment of airways throughout bronchial tree demonstrates airway narrowing in severe asthma

RATIONALE AND OBJECTIVES

To analyze airway dimensions throughout the bronchial tree in severe asthmatic patients using multidetector row computed tomography (MDCT) focusing on airway narrowing.

MATERIALS AND METHODS

Thirty-two patients with severe asthma underwent automated (BronCare software) analysis of their right lung bronchi, with counts of airways >3 mm long arising from the main bronchi (airway count) and bronchial dimension quantification at segmental and subsegmental levels (lumen area [LA], wall area [WA], and WA%). Focal bronchial stenosis was defined as >50% narrowing of maximal LA on contiguous cross-sectional slices. Severe asthmatics were compared to 13 nonsevere asthmatic patients and nonasthmatic (pooled) subjects (Wilcoxon rank tests, then stepwise logistic regression). Finally, cluster analysis of severe asthmatic patients and stepwise logistic regression identified specific imaging subgroups.

RESULTS

The most significant differences between severe asthmatic patients and the pooled subjects were bronchial stenosis (subsegmental and all bronchi: P < .002) and WA% (P < .0003). Stepwise logistic regression retained WA% as the only explanatory covariable (P = .002). Two identified clusters of severe asthmatic patients differed for parameters characterizing airway narrowing (airway count: P = .0002; focal bronchial stenosis: P = .009). Airway count was as discriminant as forced expiratory volume in 1 second/forced vital capacity (P = .01) to identify patients in each cluster, with both variables being correlated (r = 0.59, P = .005).

CONCLUSIONS

Severe asthma-associated morphologic changes were characterized by focal bronchial stenoses and diffuse airway narrowing; the latter was associated with airflow obstruction. WA%, dependent on airway caliber, is the best parameter to identify severe asthmatic patients from pooled subjects.

Sex steroid signaling: implications for lung diseases

There is increasing recognition that sex hormones (estrogen, progesterone, and testosterone) have biological and pathophysiological actions in peripheral, non-reproductive organs, including the lung. Clinically, sex differences in the incidence, morbidity and mortality of lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, lung cancer and pulmonary hypertension have been noted, although intrinsic sex differences vs. the roles of sex steroids are still not well-understood. Accordingly, it becomes important to ask the following questions: 1) Which sex steroids are involved? 2) How do they affect different components of the lung under normal circumstances? 3) How does sex steroid signaling change in or contribute to lung disease, and in this regard, are sex steroids detrimental or beneficial? As our understanding of sex steroid signaling in the lung improves, it is important to consider whether such information can be used to develop new therapeutic strategies to target lung diseases, perhaps in both sexes or in a sex-specific manner. In this review, we focus on the basics of sex steroid signaling, and the current state of knowledge regarding how they influence structure and function of specific lung components across the life span and in the context of some important lung diseases. We then summarize the potential for sex steroids as useful biomarkers and therapeutic targets in these lung diseases as a basis for future translational research in the area of gender and individualized medicine.

Semisynthesis, ex vivo evaluation, and SAR studies of coumarin derivatives as potential antiasthmatic drugs

Asthma is a chronic inflammatory disorder that causes contraction in the smooth muscle of the airway and blocking of airflow. Reversal the contractile process is a strategy for the search of new drugs that could be used for the treatment of asthma. This work reports the semisynthesis, ex vivo relaxing evaluation and SAR studies of a series of 18 coumarins. The results pointed that the ether derivatives 1-3, 7-9 and 13-15 showed the best activity (Emax = 100%), where compound 2 (42 μM) was the most potent, being 4-times more active than theophylline (positive control). The ether homologation (methyl, ethyl and propyl) in position 7 or positions 6 and 7 of coumarins lead to relaxing effect, meanwhile formation of esters generated less active compounds than ethers. The SAR analysis showed that it is necessary the presence of two small ether groups and the methyl group at position 4 (site 3) encourage biological activity through soft hydrophobic changes in the molecule, without drastically affecting the cLogP.

Airway smooth muscle in airway reactivity and remodeling: what have we learned?

It is now established that airway smooth muscle (ASM) has roles in determining airway structure and function, well beyond that as the major contractile element. Indeed, changes in ASM function are central to the manifestation of allergic, inflammatory, and fibrotic airway diseases in both children and adults, as well as to airway responses to local and environmental exposures. Emerging evidence points to novel signaling mechanisms within ASM cells of different species that serve to control diverse features, including 1) [Ca(2+)]i contractility and relaxation, 2) cell proliferation and apoptosis, 3) production and modulation of extracellular components, and 4) release of pro- vs. anti-inflammatory mediators and factors that regulate immunity as well as the function of other airway cell types, such as epithelium, fibroblasts, and nerves. These diverse effects of ASM "activity" result in modulation of bronchoconstriction vs. bronchodilation relevant to airway hyperresponsiveness, airway thickening, and fibrosis that influence compliance. This perspective highlights recent discoveries that reveal the central role of ASM in this regard and helps set the stage for future research toward understanding the pathways regulating ASM and, in turn, the influence of ASM on airway structure and function. Such exploration is key to development of novel therapeutic strategies that influence the pathophysiology of diseases such as asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis.

A new approach for the study of lung smooth muscle phenotypes and its application in a murine model of allergic airway inflammation

Phenotypes of lung smooth muscle cells in health and disease are poorly characterized. This is due, in part, to a lack of methodologies that allow for the independent and direct isolation of bronchial smooth muscle cells (BSMCs) and vascular smooth muscle cells (VSMCs) from the lung. In this paper, we describe the development of a bi-fluorescent mouse that permits purification of these two cell populations by cell sorting. By subjecting this mouse to an acute allergen based-model of airway inflammation that exhibits many features of asthma, we utilized this tool to characterize the phenotype of so-called asthmatic BSMCs. First, we examined the biophysical properties of single BSMCs from allergen sensitized mice and found increases in basal tone and cell size that were sustained ex vivo. We then generated for the first time, a comprehensive characterization of the global gene expression changes in BSMCs isolated from the bi-fluorescent mice with allergic airway inflammation. Using statistical methods and pathway analysis, we identified a number of differentially expressed mRNAs in BSMCs from allergen sensitized mice that code for key candidate proteins underlying changes in matrix formation, contractility, and immune responses. Ultimately, this tool will provide direction and guidance for the logical development of new markers and approaches for studying human lung smooth muscle.

A review on leukotrienes and their receptors with reference to asthma

OBJECTIVE AND METHODS

Leukotrienes (LTs) including cysteinyl leukotrienes (CysLTs) and LTB4 are the most potent inflammatory lipid mediators and play a central role in the pathophysiology of asthma and other inflammatory diseases. These biological molecules mediate a plethora of contractile and inflammatory responses through specific interaction with distinct G protein-coupled receptors (GPCRs). The main objective of this review is to present an overview of the biological effects of CysLTs and their receptors, along with the current knowledge of mechanisms and role of LTs in the pathogenesis of asthma.

RESULTS

CysLTs including LTC4, LTD4 and LTE4 are ligands for CysLT1 and CysLT2 receptors, and LTB4 is the agonist for BLT1 and BLT2 receptors. The role of CysLT1 receptor is well established, and most of the pathophysiological effects of CysLTs in asthma are mediated by CysLT1 receptor. Several CysLT1 antagonists have been developed to date and are currently in clinical practice. Most common among them are classical CysLT1 receptor antagonists such as montelukast, zafirlukast, pranlukast, pobilukast, iralukast, cinalukast and MK571. The pharmacological role of CysLT2 receptor, however, is less defined and there is no specific antagonist available so far. The recent demonstration that mice lacking both known CysLT receptors exhibit full/augmented response to CysLT points to the existence of additional subtypes of CysLT receptors. LTB4, on the other hand, is another potent inflammatory leukotriene, which acts as a strong chemoattractant for neutrophils, but weaker for eosinophils. LTB4 is known to play an important role in the development of airway hyper-responsiveness in severe asthma. However there is no LTB4 antagonist available in clinic to date.

CONCLUSION

This review gives a recent update on the LTs including their biosynthesis, biological effects and the role of anti-LTs in the treatment of asthma. It also discusses about the possible existence of additional subtypes of CysLT receptors.

Effect of TRPV1 channel on the proliferation and apoptosis in asthmatic rat airway smooth muscle cells

BACKGROUND

Hyperplasia of airway smooth muscle cells (ASMC) is a major contributor to airway remodeling in asthma. Transient receptor potential vanilloid 1 (TRPV1) is an important channel to mediate Ca(2+) influx. This study explores the expression of TRPV1 channel and its effect on the proliferation and apoptosis in rat ASMC, in order to find a new target to treat airway remodeling in asthma.

METHODS

Rats were sensitized and challenged with ovalbumin to replicate asthmatic models. Proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry. Reverse transcriptase-polymerase chain reaction, immunocytochemistry, and Western blot were used to detect the mRNA and protein expression of TRPV1 channel. Intracellular calcium ([Ca(2+)]i) was detected using confocal fluorescence Ca(2+) imaging. [(3)H] thymidine incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were used to observe the DNA synthesis and proliferation. TUNEL assay was used to detect the apoptosis of ASMC.

RESULTS

(1) The expression of PCNA was significantly increased in intact asthmatic rat ASMC. (2) The expression of TRPV1 channel was significantly increased in asthmatic rat ASMC. (3) [Ca(2+)]i in ASMC of the asthmatic group was significantly increased. After treatment with TRPV1 agonist capsaicin (CAP), [Ca(2+)]i was further increased, whereas [Ca(2+)]i was decreased after administration of TRPV1 antagonist capsazepine (CPZ) in ASMC of the asthmatic group. (4) The DNA synthesis and absorbance of MTT were significantly increased, while apoptosis was significantly decreased in asthmatic ASMC. CAP further enhanced proliferation and decreased apoptosis. CPZ significantly inhibited the effect of CAP in asthmatic ASMC.

CONCLUSION

TRPV1 channel was involved in the regulation of proliferation and apoptosis in asthmatic ASMC.

Glucocorticoid-induced changes in gene expression of airway smooth muscle in patients with asthma

RATIONALE

Glucocorticoids are the mainstay of asthma therapy. However, it is unclear whether the benefits of glucocorticoids in asthma are merely based on antiinflammatory properties. Glucocorticoids may also alter gene expression of airway smooth muscle (ASM). We hypothesized that the gene expression profile of the ASM layer in endobronchial biopsies of patients with asthma is altered by oral glucocorticoid therapy as compared with placebo.

OBJECTIVES

First, we investigated the change in ASM transcriptomic profile in endobronchial biopsies after 14 days of oral glucocorticoid therapy. Second, we investigated the association between changes in ASM transcriptomic profile and lung function.

METHODS

Twelve steroid-free patients with atopic asthma were included in this double-blind intervention study. Endobronchial biopsies were taken before and after 14 days of oral prednisolone (n = 6) or placebo (n = 6). RNA of laser-dissected ASM was sequenced (RNA-Seq) using GS FLX+ (454/Roche). Gene networks were identified by Ingenuity Pathway Analysis. RNA-Seq reads were assumed to follow a negative binomial distribution. At the current sample size the estimated false discovery rate was approximately 3%.

MEASUREMENTS AND MAIN RESULTS

Fifteen genes were significantly changed by 14 days of oral prednisolone. Two of these genes (FAM129A, SYNPO2) were associated with airway hyperresponsiveness (provocative concentration of methacholine causing a 20% drop in FEV1: r = -0.740, P < 0.01; r = -0.746, P < 0.01). Pathway analysis revealed three gene networks that were associated with cellular functions including cellular growth, proliferation, and development.

CONCLUSIONS

Oral prednisolone changes the transcriptomic profile of the ASM layer in asthma. This indicates that in parallel to antiinflammatory properties, glucocorticoids also exert effects on gene expression of ASM, which is correlated with improved airway function.

Curcumin inhibits the proliferation of airway smooth muscle cells in vitro and in vivo

The inhibition of the proliferation of airway smooth muscle cells (ASMCs) is crucial for the prevention and treatment of asthma. Recent studies have revealed some important functions of curcumin; however, its effects on the proliferation of ASMCs in asthma remain unknown. Therefore, in this study, we performed in vitro and in vivo experiments to investigate the effects of curcumin on the proliferation of ASMCs in asthma. The thickness of the airway wall, the airway smooth muscle layer, the number of ASMCs and the expression of extracellular signal-regulated kinase (ERK) were significantly reduced in the curcumin-treated group as compared with the model group. Curcumin inhibited the cell proliferation induced by platelet-derived growth factor (PDGF) and decreased the PDGF-induced phosphorylation of ERK1/2 in the rat ASMCs. Moreover, the disruption of caveolae using methyl-β-cyclodextrin (MβCD) attenuated the anti-proliferative effects of curcumin in the ASMCs, which suggests that caveolin is involved in this process. Curcumin upregulated the mRNA and protein expression of caveolin-1. The data presented in this study demonstrate that the proliferation of ASMCs is inhibited by curcumin in vitro and in vivo; curcumin exerts these effects by upregulating the expression of caveolin-1 and blocking the activation of the ERK pathway.

Anti-inflammatory dimethylfumarate: a potential new therapy for asthma?

Asthma is a chronic inflammatory disease of the airways, which results from the deregulated interaction of inflammatory cells and tissue forming cells. Beside the derangement of the epithelial cell layer, the most prominent tissue pathology of the asthmatic lung is the hypertrophy and hyperplasia of the airway smooth muscle cell (ASMC) bundles, which actively contributes to airway inflammation and remodeling. ASMCs of asthma patients secrete proinflammatory chemokines CXCL10, CCL11, and RANTES which attract immune cells into the airways and may thereby initiate inflammation. None of the available asthma drugs cures the disease—only symptoms are controlled. Dimethylfumarate (DMF) is used as an anti-inflammatory drug in psoriasis and showed promising results in phase III clinical studies in multiple sclerosis patients. In regard to asthma therapy, DMF has been anecdotally reported to reduce asthma symptoms in patients with psoriasis and asthma. Here we discuss the potential use of DMF as a novel therapy in asthma on the basis of in vitro studies of its inhibitory effect on ASMC proliferation and cytokine secretion in ASMCs.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger in muscarinic receptor-induced contraction of guinea pig trachea

Nicotinic acid adenine dinucleotide phosphate (NAADP) is increasingly being demonstrated to be involved in calcium signaling in many cell types and species. Although it has been shown to play a role in smooth muscle cell contraction in several tissues, nothing is known about its possible role in tracheal smooth muscle, a muscle type that is clinically relevant to asthma. To determine whether NAADP functions as a second messenger in tracheal smooth muscle contraction, we used the criteria set out by Sutherland for a molecule to be designated a second messenger. We report that NAADP satisfies all five criteria as follows. First, the NAADP antagonist Ned-19 inhibited contractions in tracheal rings and calcium increases in isolated smooth muscle cells induced by the muscarinic agonist carbachol. Second, NAADP increased cytosolic calcium in isolated cells when microinjected and was blocked by Ned-19. Third, tracheal homogenates could synthesize NAADP by base exchange from exogenous NADP and nicotinic acid and metabolize exogenous NAADP to nicotinic acid adenine dinucleotide by a 2'-phosphatase. Fourth, carbachol induced a rapid and transient increase in endogenous NAADP levels. Fifth, tracheal homogenates contained NAADP-binding sites of high affinity. Taken together, these data demonstrate that NAADP functions as a second messenger in tracheal smooth muscle, and therefore, steps in the NAADP signaling pathway might provide possible new drug targets.

BRET Biosensor Analysis of Receptor Tyrosine Kinase Functionality

Bioluminescence resonance energy transfer (BRET) is an improved version of earlier resonance energy transfer technologies used for the analysis of biomolecular protein interaction. BRET analysis can be applied to many transmembrane receptor classes, however the majority of the early published literature on BRET has focused on G protein-coupled receptor (GPCR) research. In contrast, there is limited scientific literature using BRET to investigate receptor tyrosine kinase (RTK) activity. This limited investigation is surprising as RTKs often employ dimerization as a key factor in their activation, as well as being important therapeutic targets in medicine, especially in the cases of cancer, diabetes, neurodegenerative, and respiratory conditions. In this review, we consider an array of studies pertinent to RTKs and other non-GPCR receptor protein-protein signaling interactions; more specifically we discuss receptor-protein interactions involved in the transmission of signaling communication. We have provided an overview of functional BRET studies associated with the RTK superfamily involving: neurotrophic receptors [e.g., tropomyosin-related kinase (Trk) and p75 neurotrophin receptor (p75NTR)]; insulinotropic receptors [e.g., insulin receptor (IR) and insulin-like growth factor receptor (IGFR)] and growth factor receptors [e.g., ErbB receptors including the EGFR, the fibroblast growth factor receptor (FGFR), the vascular endothelial growth factor receptor (VEGFR) and the c-kit and platelet-derived growth factor receptor (PDGFR)]. In addition, we review BRET-mediated studies of other tyrosine kinase-associated receptors including cytokine receptors, i.e., leptin receptor (OB-R) and the growth hormone receptor (GHR). It is clear even from the relatively sparse experimental RTK BRET evidence that there is tremendous potential for this technological application for the functional investigation of RTK biology.