Beta-adrenoceptor agonists and asthma--100 years of development

Modular and Practical 1,2-Aryl(Alkenyl) Heteroatom Functionalization of Alkenes through Iron/Photoredox Dual Catalysis

Efficient methods for synthesizing 1,2-aryl(alkenyl) heteroatomic cores, encompassing heteroatoms such as nitrogen, oxygen, sulfur, and halogens, are of significant importance in medicinal chemistry and pharmaceutical research. In this study, we present a mild, versatile and practical photoredox/iron dual catalytic system that enables access to highly privileged 1,2-aryl(alkenyl) heteroatomic pharmacophores with exceptional efficiency and site selectivity. Our approach exhibits an extensive scope, allowing for the direct utilization of a wide range of commodity or commercially available (hetero)arenes as well as activated and unactivated alkenes with diverse functional groups, drug scaffolds, and natural product motifs as substrates. By merging iron catalysis with the photoredox cycle, a vast array of alkene 1,2-aryl(alkenyl) functionalization products that incorporate a neighboring azido, amino, halo, thiocyano and nitrooxy group were secured. The scalability and ability to rapid synthesize numerous bioactive small molecules from readily available starting materials highlight the utility of this protocol.

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

Evaluation of the possible effect of inspiratory muscle training on inflammation markers and oxidative stress in childhood asthma

Airway inflammation characterized as asthma is one of the most common chronic diseases in the world. The aim of this study was to evaluate the possible effect of inspiratory muscle training on inflammation markers and oxidative stress levels in childhood asthma. A total of 105 children (age range 8-17 years), including 70 asthmatics and 35 healthy children, participated in the study. The 70 asthma patients were randomly assigned to the inspiratory muscle training (IMT) group (n = 35) and control group (n = 35), and healthy children were assigned to the healthy group (n = 35). The IMT group was treated with the threshold IMT device for 7 days/6 weeks at 30% of maximum inspiratory pressure. Respiratory muscle strength was evaluated with a mouth pressure measuring device, and respiratory function was evaluated with a spirometer. In addition, CRP, periostin, TGF-β, and oxidative stress levels were analyzed. The evaluation was performed only once in the healthy group and twice (at the beginning and end of 6 weeks) in asthma patients. In the study, there were significant differences between asthma patients and the healthy group in terms of MIP and MEP values, respiratory function, oxidative stress level, periostin, and TGF-β. Post-treatment, differences were observed in the oxidative stress level, periostin, and TGF-β of the IMT group (p < .05).

CONCLUSION

After 6 weeks of training, IMT positively contributed to reducing the inflammation level and oxidative stress. This suggests that IMT should be used as an alternative therapy to reduce inflammation and oxidative stress. (Trial Registration: The clinical trial protocol number is NCT05296707).

WHAT IS KNOWN

• It is known that adjunctive therapies given in addition to pharmacological treatment contribute to improving symptom control and quality of life in individuals with asthma.

WHAT IS NEW

• There are no studies about the effect of respiratory physiotherapy on biomarkers in asthmatic children. The sub-mechanism of improvement in individuals has not been elucidated. • In this context, inspiratory muscle training has a positive effect on inflammation and oxidative stress levels in children with asthma and IMT should be used as an alternative treatment for childhood asthma.

Anti-asthmatic fraction screening and mechanisms prediction of Schisandrae Sphenantherae Fructus based on a combined approach

Objective: Schisandrae Sphenantherae Fructus (SSF) is a traditional Chinese medicine used to treat coughs and pulmonary inflammatory diseases. However, the pharmacodynamic material basis and mechanisms for SSF in asthma treatment remain unclear. This study aims to screen the anti-asthmatic fraction and verify the pharmacodynamic material basis, predict the potential mechanism, and verify the interaction ability between compounds and core targets.

Methods: First, three fractions from SSF were compared in terms of composition, comparison, and anti-asthmatic effects. Then, the ultra-performance liquid chromatography-quadrupole/time-of-flight-mass spectrometry/mass spectrometry (UPLC-Q/TOF-MS/MS) strategy was used to identify the compounds from the active fraction, and the anti-asthmatic efficacy of the active fraction was further studied by the ovalbumin (OVA)-induced asthma murine model. Finally, network pharmacology and molecular methods were used to study the relationships between active compounds, core targets, and key pathways of PEF in asthma treatments.

Results: The petroleum ether fraction (PEF) of SSF showed better effects and could significantly diminish lung inflammation and mitigate the level of serum immunoglobulin E (IgE), interleukin (IL)-4, IL-5, IL-6, IL-13, and IL-17 in mice. A total of 26 compounds from the PEF were identified, among which the main compounds are lignans and triterpenes. Moreover, 21 active compounds, 129 overlap-ping targets, and 10 pathways were screened by network pharmacology tools. The top five core targets may play a great role in asthma treatment. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that the PEF can treat asthma by acting on multiple asthma pathological processes, including the IL-17 signaling pathway, T helper (Th) 17 cell differentiation, and the calcium signaling pathway. Molecular docking was performed to evaluate the interactions of the protein–ligand binding, and most docked complexes had a good binding ability.

Conclusion: The present results might contribute to exploring the active compounds with anti-asthmatic activity.

Discovery of a Highly Selective β2-Adrenoceptor Agonist with a 2-Amino-2-phenylethanol Scaffold as an Oral Antiasthmatic Agent

Asthma patients in resource-poor countries cannot obtain adequate basic asthma medications because most asthma medications are supplied as inhalants. An alternative approach is to create oral antiasthmatic drugs with high β₂/β₁-selectivity, which should reduce treatment costs. In this study, we designed a cohort of compounds 1 using 2-(4-amino-3-chloro-5-(trifluoromethyl)phenyl)-2-(tert-butylamino)ethan-1-ol hydrogen chloride (1a) as the lead compound with an aim to expand the library of compounds possessing the 2-amino-2-phenylethanol scaffold. Structure-activity relationship studies on these compounds revealed that compounds created showed remarkable β₂ selectivity compared to isoproterenol and gave additional insights on the rational design of β₂-adrenoceptor agonists. Moreover, 1a was found as the best candidate compound showing the greatest potential for drug development. Cell-based assays showed that 1a was about 10 times more selective than salbutamol toward the β₂-adrenoceptor. Moreover, 1a exhibited good oral bioavailability and low acute oral toxicity. These data reveal 1a as an oral antiasthmatic agent.

Molecular determinants of GPCR pharmacogenetics: Deconstructing the population variants in β2-adrenergic receptor

G protein-coupled receptors (GPCRs) are membrane proteins that play a central role in cell signaling and constitute one of the largest classes of drug targets. The molecular mechanisms underlying GPCR function have been characterized by several experimental and computational methods and provide an understanding of their role in physiology and disease. Population variants arising from nsSNPs affect the native function of GPCRs and have been implicated in differential drug response. In this chapter, we provide an overview on GPCR structure and activation, with a special focus on the β₂-adrenergic receptor (β₂-AR). First, we discuss the current understanding of the structural and dynamic features of the wildtype receptor. Subsequently, the population variants identified in this receptor from clinical and large-scale genomic studies are described. We show how computational approaches such as bioinformatics tools and molecular dynamics simulations can be used to characterize the variant receptors in comparison to the wildtype receptor. In particular, we discuss three examples of clinically important variants and discuss how the structure and function of these variants differ from the wildtype receptor at a molecular level. Overall, the chapter provides an overview of structure and function of GPCR variants and is a step towards the study of inter-individual differences and personalized medicine.

Prevention and Treatment of Asthma Exacerbations in Adults

Asthma exacerbations are major contributors to disease morbidity in patients of all ages. To develop strategies that reduce the disease burden from exacerbations, it is helpful to review current concepts about the risk factors for asthma attacks and current approaches for prevention and treatment. Multiple factors contribute as risks and to the development of asthma exacerbations, including allergic and infectious processes. Viral respiratory infections, primarily from rhinoviruses, are the dominant exacerbating cause for most asthma patients. Allergic sensitization and allergen exposure contribute directly and enhance susceptibility for respiratory viral infections. Respiratory viruses infect airway epithelium to promote underlying type 2 inflammation with eosinophils, the predominant cellular component of increased inflammation. Deficiencies of antiviral interferon responses and generation have been identified that increase susceptibility to viral infections in asthma. Exacerbation treatment focuses on reducing airflow obstruction and suppressing inflammation, followed by improving long-term asthma control. Increasing concern exists regarding the side effects associated with frequent systemic corticosteroid use. A major advance has been the selective use of biologics to prevent exacerbations, primarily in patients with existing type 2 inflammation. Future research to prevent exacerbations is being directed toward antiviral activity and a more encompassing regulation of underlying airway inflammation.

VAMS and StAGE as innovative tools for the enantioselective determination of clenbuterol in urine by LC-MS/MS

Clenbuterol is a chiral, selective β₂-adrenergic agonist. It is administered as a racemic mixture for therapeutic purposes (as a bronchodilator or prospective neuroprotective agent), but also for non-therapeutic uses (athletic performance enhancement, cattle growth promotion). Aim of the present study is to develop an original, enantioselective workflow for the analysis of clenbuterol enantiomers in urine microsamples. An innovative miniaturised sampling procedure by volumetric absorptive microsampling (VAMS) and a microsample pretreatment strategy based on stop-and-go extraction (StAGE) tips were developed and coupled to an original, chiral analytical method, exploiting liquid chromatography with triple quadrupole detection (LC-MS/MS). The method was validated, with satisfactory results: good linearity (r² ≥ 0.9995) and LOQ values (0.3 ng/mL) were found over suitable concentration ranges. Extraction yield (>87 %), precision (RSD < 4.3 %) and matrix effect (85-90 %) were all within acceptable levels of confidence. After validation, the method was applied to the determination of clenbuterol in dried urine sampled by VAMS from patients taking the drug for therapeutic reasons. Analyte content ranged from 0.8 to 2.5 ng/mL per single enantiomer, with substantial retention of the original drug racemic composition. The VAMS-StAGE-LC-MS/MS workflow seems to be suitable for future application to anti-doping testing of clenbuterol in urine.

The strategies and techniques of drug discovery from natural products

Natural products have been the main sources of new drugs. The different strategies have been developed to find the new drugs based on natural products. The traditional and ethic medicines have provided information on the therapeutic effects and resulted in some notable drug discovery of natural products. The special activities of the medicine plants such as the side effects have inspired scientists to develop the novel small molecular. The microorganisms and the endogenous active substances from human or animal also become the important approaches to the drug discovery. The tremendous progress in technology led to the new strategies in drug discovery from natural products. The bioinformation and artificial intelligence have facilitated the research and development of natural products. We will provide a scene of strategies and technologies for drug discovery from natural products in this review.

Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis

β2-Agonists (β2-adrenergic agonists, bronchodilatants, and sympathomimetic drugs) are a group of drugs that are mainly used in asthma and obstructive pulmonary diseases. In practice, the substances used to contain one or more stereogenic centers in their structure and their enantiomers exhibit different pharmacological properties. In terms of bronchodilatory activity, (R)-enantiomers showed higher activity. The investigation of stereoselectivity in action and disposition of chiral drugs together with the preparation of pure enantiomer drugs calls for efficient stereoselective analytical methods. The overview focuses on the stereoselectivity in pharmacodynamics and pharmacokinetics of β2-agonists and summarizes the stereoselective analytical methods for the enantioseparation of racemic beta-agonists (HPLC, LC-MS, GC, TLC, CE). Some methods of the stereoselective synthesis for β2-agonists preparation are also presented.

New approach to intermittent and mild asthma therapy: evolution or revolution in the GINA guidelines?

New recommendations from the Global Initiative for Asthma (GINA) were released in a pocket guide form on April 12, 2019. These recommendations provide very important changes to the management of asthma, especially regarding the treatment of intermittent and mild asthma. Due to safety concerns, GINA experts no longer recommend treatment with a short-acting β2 agonist alone. Henceforth, all adults and adolescents (but not yet children) with mild asthma should receive either symptom-driven or daily low-dose ICS. The main goal of this new approach is to reduce the risk of serious asthma exacerbations and asthma-related deaths in the population of patients with mild asthma. Herein, the authors present the epidemiological and clinical data regarding the risks of excessive SABA use and the benefits of regular treatment with inhaled corticosteroids. The authors deliver a critical review on the evolution of the changes in the GINA experts’ standpoint and provide evidence-based background for the new approach to asthma treatment. Moreover, the authors identify gaps and unmet needs still present in the current asthma management recommendations and discuss them thoroughly.

Discovery of potential asthma targets based on the clinical efficacy of Traditional Chinese Medicine formulas

ETHNOPHARMACOLOGICAL RELEVANCE

Standard therapy for asthma, a highly heterogeneous disease, is primarily based on bronchodilators and immunosuppressive drugs, which confer short-term symptomatic relief but not a cure. It is difficult to discover novel bronchodilators, although potential new targets are emerging. Traditional Chinese Medicine (TCM) formulas have been used to treat asthma for more than 2000 years, forming the basis for representative asthma treatments.

AIM OF THE STUDY

Based on the efficacy of TCM formulas, anti-asthmatic herbal compounds bind proteins are potential targets for asthma therapy. This analysis will provide new drug targets and discovery strategies for asthma therapy.

MATERIALS AND METHODS

A list of candidate herbs for asthma was selected from the classical formulas (CFs) of TCM for the treatment of wheezing or dyspnea recorded in Treatise on Cold Damage and Miscellaneous Diseases (TCDMD) and from modern herbal formulas identified in the SAPHRON TCM Database using the keywords "wheezing" or "dyspnea". Compounds in the selected herbs and compounds that directly bind target proteins were acquired by searching the Herbal Ingredients' Targets Database (HITD), TCM Data Bank (TCMDB) and TCM Integrated Database (TCMID). Therapeutic targets of conventional medicine (CM) for asthma were collected by searching Therapeutic Target Database (TTD), DrugBank and PubMed as supplements. Finally, the enriched gene ontology (GO) terms of the targets were obtained using the Database for Annotation Visualization and Integrated Discovery (DAVID) and protein-protein interactions (PPI) networks were constructed using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING). The effects of two selected TCM compounds, kaempferol and ginkgolide A, on cellular resistance in human airway smooth muscle cells (ASMCs) and pulmonary resistance in a mouse model were investigated.

RESULTS

The list of 32 candidate herbs for asthma was selected from 10 CFs for the treatment of wheezing or dyspnea recorded in TCDMD and 1037 modern herbal formulas obtained from the SAPHRON TCM Database. A total of 130 compounds from the 32 selected herbs and 68 herbal compounds directly bind target proteins were acquired from HITD and TCMDB. Eighty-eight therapeutic targets of CM for asthma were collected by searching TTD and PubMed as supplements. DAVID and STRING analyses showed targets of TCM formulas are primarily related to cytochrome P450 (CYP) family, transient receptor potential (TRP) channels, matrix metalloproteinases (MMPs) and ribosomal protein. Both TCM formulas and CM act on the same types of targets or signaling pathways, such as G protein-coupled receptors (GPCRs), steroid hormone receptors (SHRs), and JAK-STAT signaling pathway. The proteins directly targeted by herbal compounds, TRPM8, TRPA1, TRPV3, CYP1B1, CYP2B6, CYP1A2, CYP3A4, CYP1A1, PPARA, PPARD, NR1I2, MMP1, MMP2, ESR1, ESR2, RPLP0, RPLP1 and RPLP2, are potential targets for asthma therapy. In vitro results showed kaempferol (1 × 10^-2 mM) and ginkgolide A (1 × 10^-5 mM) significantly increased the cell index (P < 0.05 vs. histamine, n = 3) and therefore relaxed human ASMCs. In vivo results showed kaempferol (145 μg/kg) and ginkgolide A (205 μg/kg) significantly reduced pulmonary resistance (P < 0.05 vs. methacholine, n = 6).

CONCLUSION

Potential target discovery for asthma treatment based on the clinical effectiveness of TCM is a feasible strategy.

Mechanisms and Management of Asthma Exacerbations

Acute asthma remains an important medical emergency, the most frequent cause of acute admissions in children and a major source of morbidity for adults with asthma. In all ages with asthma, the presence of exacerbations is an important defining characteristic of asthma severity. In this review, we assess the epidemiology of acute asthma, the triggers of acute exacerbations, and the mechanisms that underlie these exacerbations. We also assess current treatments that prevent exacerbations, with an emphasis on the role of type 2 airway inflammation in the context of acute exacerbations and the novel treatments that effectively target this. Finally we review current management strategies of the exacerbations themselves.

G Protein-Coupled Receptors in Asthma Therapy: Pharmacology and Drug Action

Asthma is a heterogeneous inflammatory disease of the airways that is associated with airway hyperresponsiveness and airflow limitation. Although asthma was once simply categorized as atopic or nonatopic, emerging analyses over the last few decades have revealed a variety of asthma endotypes that are attributed to numerous pathophysiological mechanisms. The classification of asthma by endotype is primarily routed in different profiles of airway inflammation that contribute to bronchoconstriction. Many asthma therapeutics target G protein-coupled receptors (GPCRs), which either enhance bronchodilation or prevent bronchoconstriction. Short-acting and long-acting β 2-agonists are widely used bronchodilators that signal through the activation of the β 2-adrenergic receptor. Short-acting and long-acting antagonists of muscarinic acetylcholine receptors are used to reduce bronchoconstriction by blocking the action of acetylcholine. Leukotriene antagonists that block the signaling of cysteinyl leukotriene receptor 1 are used as an add-on therapy to reduce bronchoconstriction and inflammation induced by cysteinyl leukotrienes. A number of GPCR-targeting asthma drug candidates are also in different stages of development. Among them, antagonists of prostaglandin D2 receptor 2 have advanced into phase III clinical trials. Others, including antagonists of the adenosine A2B receptor and the histamine H4 receptor, are in early stages of clinical investigation. In the past decade, significant research advancements in pharmacology, cell biology, structural biology, and molecular physiology have greatly deepened our understanding of the therapeutic roles of GPCRs in asthma and drug action on these GPCRs. This review summarizes our current understanding of GPCR signaling and pharmacology in the context of asthma treatment. SIGNIFICANCE STATEMENT: Although current treatment methods for asthma are effective for a majority of asthma patients, there are still a large number of patients with poorly controlled asthma who may experience asthma exacerbations. This review summarizes current asthma treatment methods and our understanding of signaling and pharmacology of G protein-coupled receptors (GPCRs) in asthma therapy, and discusses controversies regarding the use of GPCR drugs and new opportunities in developing GPCR-targeting therapeutics for the treatment of asthma.

Many continuous variables should be analyzed using the relative scale: a case study of β2-agonists for preventing exercise-induced bronchoconstriction

BACKGROUND

The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochrane systematic review that reported only absolute effects of inhaled β₂-agonists on exercise-induced decline in forced-expiratory volumes in 1 s (FEV₁).

METHODS

From the Cochrane review, we selected placebo-controlled cross-over studies that reported individual participant data (IPD). Reversal in FEV₁ decline after exercise was modeled as a mean uniform percentage point (pp) change (absolute effect) or average percent change (relative effect) using either intercept-only or slope-only, respectively, linear mixed-effect models. We also calculated the pooled relative effect estimates using standard random-effects, inverse-variance-weighting meta-analysis using study-level mean effects.

RESULTS

Fourteen studies with 187 participants were identified for the IPD analysis. On the absolute scale, β₂-agonists decreased the exercise-induced FEV₁ decline by 28 pp., and on the relative scale, they decreased the FEV₁ decline by 90%. The fit of the statistical model was significantly better with the relative 90% estimate compared with the absolute 28 pp. estimate. Furthermore, the median residuals (5.8 vs. 10.8 pp) were substantially smaller in the relative effect model than in the absolute effect model. Using standard study-level meta-analysis of the same 14 studies, β₂-agonists reduced exercise-induced FEV₁ decline on the relative scale by a similar amount: 83% or 90%, depending on the method of calculating the relative effect.

CONCLUSIONS

Compared with the absolute scale, the relative scale captures more effectively the variation in the effects of β₂-agonists on exercise-induced FEV₁-declines. The absolute scale has been used in the analysis of FEV₁ changes and may have led to sub-optimal statistical analysis in some cases. The choice between the absolute and relative scale should be determined based on biological reasoning and empirical testing to identify the scale that leads to lower heterogeneity.

Beta-2 Adrenergic and Glucocorticoid Receptor Agonists Modulate Ozone-Induced Pulmonary Protein Leakage and Inflammation in Healthy and Adrenalectomized Rats

We have shown that acute ozone inhalation activates sympathetic-adrenal-medullary and hypothalamus-pituitary-adrenal stress axes, and adrenalectomy (AD) inhibits ozone-induced lung injury and inflammation. Therefore, we hypothesized that stress hormone receptor agonists (β2 adrenergic-β2AR and glucocorticoid-GR) will restore the ozone injury phenotype in AD, while exacerbating effects in sham-surgery (SH) rats. Male Wistar Kyoto rats that underwent SH or AD were treated with vehicles (saline + corn oil) or β2AR agonist clenbuterol (CLEN, 0.2 mg/kg, i.p.) + GR agonist dexamethasone (DEX, 2 mg/kg, s.c.) for 1 day and immediately prior to each day of exposure to filtered air or ozone (0.8 ppm, 4 h/day for 1 or 2 days). Ozone-induced increases in PenH and peak-expiratory flow were exacerbated in CLEN+DEX-treated SH and AD rats. CLEN+DEX affected breath waveform in all rats. Ozone exposure in vehicle-treated SH rats increased bronchoalveolar lavage fluid (BALF) protein, N-acetyl glucosaminidase activity (macrophage activation), neutrophils, and lung cytokine expression while reducing circulating lymphocyte subpopulations. AD reduced these ozone effects in vehicle-treated rats. At the doses used herein, CLEN+DEX treatment reversed the protection offered by AD and exacerbated most ozone-induced lung effects while diminishing circulating lymphocytes. CLEN+DEX in air-exposed SH rats also induced marked protein leakage and reduced circulating lymphocytes but did not increase BALF neutrophils. In conclusion, circulating stress hormones and their receptors mediate ozone-induced vascular leakage and inflammatory cell trafficking to the lung. Those receiving β2AR and GR agonists for chronic pulmonary diseases, or with increased circulating stress hormones due to psychosocial stresses, might have altered sensitivity to air pollution.

Revealing the Regional Localization and Differential Lung Retention of Inhaled Compounds by Mass Spectrometry Imaging

Background: For the treatment of respiratory disease, inhaled drug delivery aims to provide direct access to pharmacological target sites while minimizing systemic exposure. Despite this long-held tenet of inhaled therapeutic advantage, there are limited data of regional drug localization in the lungs after inhalation. The aim of this study was to investigate the distribution and retention of different chemotypes typifying available inhaled drugs [slowly dissolving neutral fluticasone propionate (FP) and soluble bases salmeterol and salbutamol] using mass spectrometry imaging (MSI). Methods: Salmeterol, salbutamol, and FP were simultaneously delivered by inhaled nebulization to rats. In the same animals, salmeterol-d₃, salbutamol-d₃, and FP-d₃ were delivered by intravenous (IV) injection. Samples of lung tissue were obtained at 2- and 30-minute postdosing, and high-resolution MSI was used to study drug distribution and retention. Results: IV delivery resulted in homogeneous lung distribution for all molecules. In comparison, while inhalation also gave rise to drug presence in the entire lung, there were regional chemotype-dependent areas of higher abundance. At the 30-minute time point, inhaled salmeterol and salbutamol were preferentially retained in bronchiolar tissue, whereas FP was retained in all regions of the lungs. Conclusion: This study clearly demonstrates that inhaled small molecule chemotypes are differentially distributed in lung tissue after inhalation, and that high-resolution MSI can be applied to study these retention patterns.

High Modulus Conductive Hydrogels Enhance In Vitro Maturation and Contractile Function of Primary Cardiomyocytes for Uses in Drug Screening

Effective and quick screening and cardiotoxicity assessment are very crucial for drug development. Here, a novel composite hydrogel composed of carbon fibers (CFs) with high conductivity and modulus with polyvinyl alcohol (PVA) is reported. The conductivity of the composite hydrogel PVA/CFs is similar to that of natural heart tissue, and the elastic modulus is close to that of natural heart tissue during systole, due to the incorporation of CFs. PVA/CFs remarkably enhance the maturation of neonatal rat cardiomyocytes (NRCM) in vitro by upregulating the expression of α-actinin, troponin T, and connexin-43, activating the signaling pathway of α5 and β1 integrin-dependent ILK/p-AKT, and increasing the level of RhoA and hypoxia-inducible factor-1α. As a result, the engineered cell sheet-like constructs NRCM@PVA/CFs display much more synchronous, stable, and robust beating behavior than NRCM@PVA. When exposed to doxorubicin or isoprenaline, NRCM@PVA/CFs can retain effective beating for much longer time or change the contractile rate much faster than NRCM@PVA, respectively, therefore representing a promising heart-like platform for in vitro drug screening and cardiotoxicity assessment.

Kinetics and Degradation Mechanism of Adrenaline Derivative CpQ in Diluted Aqueous Solutions

The degradation kinetics of an adrenaline (epinephrine) derivative, CpQ, was studied in solution in the pH range of 1-12 at 40-80 °C by high-performance liquid chromatography and ultraviolet-visible spectroscopy. The pH-rate profile exhibits a bell-shaped curve with two sigmoidal regions in the specific acid-catalyzed and specific base-catalyzed regions. The pH range of maximum stability was 2.5-4.5 with the main degradation pathway being the oxidative N-dealkylation of the aliphatic amino moiety followed by fast interconversion of the resulting fragments to stable degradation products. The autoxidation reaction was slower than the reaction of the oxygen reactive species. The chiral center underwent R to S racemization by a polar reaction mechanism under acidic conditions with a rate minimum at pH 4. The rates of degradation of the R and S enantiomers were similar across all pHs. CpQ degradation in the presence of hydrogen peroxide at 40 °C was significantly faster, and the extent of increases with pH. Metal ions bind to CpQ and catalyze its hydrolysis in the order Fe³⁺ > Fe²⁺ > Mg²⁺ > Mn²⁺ > Ti³⁺ > Sr²⁺ > Zn²⁺, with a rate enhancement of ≤1 order of magnitude at the studied pH values of 1 and 5. There was no buffer catalysis observed in the hydrolysis of the studied compound for maleate and phosphate but significant buffer catalysis in the case of citrate and malate.

Enantioselective resolution of Rac-terbutaline and evaluation of optically pure R-terbutaline hydrochloride as an efficient anti-asthmatic drug

Terbutaline is a β₂ -adrenoceptor agonist for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Among the two isomers of terbutaline (TBT 2), R-isomer was found to be the potent enantiomer in generating therapeutic effect, while S-isomer has been reported to show side effects. In this study, R-terbutaline hydrochloride (R-TBH 6) was synthesized through chiral resolution from the racemic terbutaline sulfate (rac-TBS 1) with 99.9% enantiomeric excess (ee) in good overall yield (53.6%). Further, R-TBH 6 nebulized solution was prepared in half dosage of Bricanyl®, which is a marketed product of racemic terbutaline and evaluated in vitro aerosol performance and in vivo anti-asthmatic effect on guinea pigs via. pulmonary delivery. From the investigation, it is evident that R-TBH 6 nebulized solution of half dosage performed similar fine aerosol characteristics and anti-asthmatic effect with Bricanyl®.

Exploring GPCR-Ligand Interactions with the Fragment Molecular Orbital (FMO) Method

The understanding of binding interactions between any protein and a small molecule plays a key role in the rationalization of affinity and selectivity. It is essential for an efficient structure-based drug design (SBDD) process. FMO enables ab initio approaches to be applied to systems that conventional quantum-mechanical (QM) methods would find challenging. The key advantage of the Fragment Molecular Orbital Method (FMO) is that it can reveal atomistic details about the individual contributions and chemical nature of each residue and water molecule toward ligand binding which would otherwise be difficult to detect without using QM methods. In this chapter, we demonstrate the typical use of FMO to analyze 19 crystal structures of β1 and β2 adrenergic receptors with their corresponding agonists and antagonists.

Molecular dynamic simulations reveal suboptimal binding of salbutamol in T164I variant of β2 adrenergic receptor

The natural variant C491T (rs1800088) in ADRB2 gene substitutes Threonine to Isoleucine at 164^th position in β2AR and results in receptor sequestration and altered binding of agonists. Present investigation pursues to identify the effect of T164I variation on function and structure of β2AR through systematic computational approaches. The study, in addition, addresses altered binding of salbutamol in T164I variant through molecular dynamic simulations. Methods involving changes in free energy, solvent accessibility surface area, root mean square deviations and analysis of binding cavity revealed structural perturbations in receptor to incur upon T164I substitution. For comprehensive understanding of receptor upon substitution, OPLS force field aided molecular dynamic simulations were performed for 10 ns. Simulations revealed massive structural departure for T164I β2AR variant from the native state along with considerably higher root mean square fluctuations of residues near the cavity. Affinity prediction by molecular docking showed two folds reduced affinity of salbutamol in T164I variant. To validate the credibility docking results, simulations for ligand-receptor complex were performed which demonstrated unstable salbutamol-T164I β2AR complex formation. Further, analysis of interactions in course of simulations revealed reduced ligand-receptor interactions of salbutamol in T164I variant. Taken together, studies herein provide structural rationales for suboptimal binding of salbutamol in T164I variant through integrated molecular modeling approaches.

β2 Agonists

History suggests β agonists, the cognate ligand of the β₂ adrenoceptor, have been used as bronchodilators for around 5,000 years, and β agonists remain today the frontline treatment for asthma and chronic obstructive pulmonary disease (COPD). The β agonists used clinically today are the products of significant expenditure and over 100 year's intensive research aimed at minimizing side effects and enhancing therapeutic usefulness. The respiratory physician now has a therapeutic toolbox of long acting β agonists to prophylactically manage bronchoconstriction, and short acting β agonists to relieve acute exacerbations. Despite constituting the cornerstone of asthma and COPD therapy, these drugs are not perfect; significant safety issues have led to a black box warning advising that long acting β agonists should not be used alone in patients with asthma. In addition there are a significant proportion of patients whose asthma remains uncontrolled. In this chapter we discuss the evolution of β agonist use and how the understanding of β agonist actions on their principal target tissue, airway smooth muscle, has led to greater understanding of how these drugs can be further modified and improved in the future. Research into the genetics of the β₂ adrenoceptor will also be discussed, as will the implications of individual DNA profiles on the clinical outcomes of β agonist use (pharmacogenetics). Finally we comment on what the future may hold for the use of β agonists in respiratory disease.

Selaginella uncinata flavonoids ameliorated ovalbumin-induced airway inflammation in a rat model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella uncinata (Desv.) Spring, known as "Cuiyuncao", is a perennial herb widely distributed in the Southeast Asian countries. In the folk medicine, the local minority commonly use it to treat cough and asthma for centuries.

AIM OF THE STUDY

This study was carried out to investigate the protective mechanisms of total flavonoids from S. uncinata (SUF) on airway hyperresponsiveness, cytokine release and bitter taste receptors (T2Rs) signaling with emphasis on inflammatory responses in a rat model of ovalbumin (OVA)-induced asthma.

MATERIALS AND METHODS

Rats were sensitized and challenged with OVA to induce typical asthmatic reactions. Pathological changes of lung tissue were examined by HE staining. The serum levels of T cell-associated cytokines (IFN-γ, IL-4, IL-5 and IL-13), total IgE and OVA-specific IgE were determined by enzyme-linked immunosorbent assay (ELISA). Gene expressions of T2R10, IP3R1 and Orai1 in lung tissue were assayed by fluorescence quantitative real-time polymerase chain reaction (FQ-PCR) while protein expressions of NFAT1 and c-Myc were assayed by western blot analysis. The activation of SUF was investigated on tansgentic T2R10-GFP HEK293 cells.

RESULTS

SUF treatment attenuated airway hyperresponsiveness and goblet cell hyperplasia compared with OVA-challenged asthmatic rats. The serum levels of IL-4, IL-5 and IL-13 as well as total and OVA-specific IgE were decreased while serum IFN-γ was increased in SUF-treated rats. SUF treatment significantly up-regulated T2R10 gene expression, down-regulated IP3R1 and Orai1 gene expression. SUF further suppressed eotaxin, NFAT1 and c-Myc protein expression in lung tissues of OVA-challenged rats.

CONCLUSIONS

These results imply that SUF exerts anti-inflammatory function through the T2R10/IP3R1/NFAT1 dependent signaling pathway, and may warrant further evaluation as a possible agent for the treatment of asthma.

β-Blockers, heart disease and COPD: current controversies and uncertainties

Treating people with cardiovascular disease and COPD causes significant clinician anxiety. β-Blockers save lives in people with heart disease, specifically postinfarction and heart failure. COPD and heart disease frequently coexist and people with both disorders have particularly high cardiovascular mortality. There are concerns about giving β-blockers to people with concomitant COPD that include reduced basal lung function, diminished effectiveness of emergency β-agonist treatments, reduced benefit of long-acting β-agonist treatment and difficulty in discriminating between asthma and COPD. β-Blockers appear to reduce lung function in both the general population and those with COPD because they are poorly selective for cardiac β1-adrenoceptors over respiratory β2-adrenoceptors, and studies have shown that higher β-agonist doses are required to overcome the β-blockade. COPD and cardiovascular disease share similar environmental risks and both disease states have high adrenergic and inflammatory activation. β-Blockers may therefore be particularly helpful in reducing cardiovascular events in this high-risk group. They may reduce the background inflammatory state, and inhibit the tachycardia and hypertension associated with both the endogenous adrenaline and high-dose β-agonist treatment associated with acute exacerbations of COPD. Some studies have suggested no increased and, at times, reduced mortality in patients with COPD taking β-blockers for heart disease. However, these are all observational studies and there are no randomised controlled trials. Potential ways to improve this dilemma include the development of highly β1-selective β-blockers or the use of non-β-blocking heart rate reducing agents, such as ivabridine, if these are proven to be beneficial in randomised controlled trials.

Evaluation of the anti-inflammatory effects of β-adrenoceptor agonists on human lung macrophages

The principal mechanism by which bronchodilator β-adrenoceptor agonists act is to relax airways smooth muscle although they may also be anti-inflammatory. However, the extent of anti-inflammatory activity and the cell types affected by these agonists are uncertain. The purpose of this study was to evaluate whether β-adrenoceptor agonists prevent pro-inflammatory cytokine generation from activated human lung macrophages. Macrophages were isolated and purified from human lung. The cells were pre-treated with both short-acting (isoprenaline, salbutamol, terbutaline) and long-acting (formoterol, salmeterol, indacaterol) β-agonists before activation with lipopolysaccharide (LPS) to induce cytokine (TNFα, IL-6, IL-8 and IL-10) generation. The experiments showed that short-acting β-agonists were poor inhibitors of cytokine generation. Of the long-acting β-agonists studied, formoterol was also a weak inhibitor of cytokine generation whereas only indacaterol and salmeterol showed moderate inhibitory activity. Further experiments using the β₂-adrenoceptor antagonist ICI-118,551 suggested that the effects of indacaterol were likely to be mediated by β₂-adrenoceptors whereas those of salmeterol were not. These findings were corroborated by functional desensitization studies in which the inhibitory effects of indacaterol appeared to be receptor-mediated whereas those of salmeterol were not. Taken together, the data indicate that the anti-inflammatory effects of β-adrenoceptor agonists on human lung macrophages are modest.

Step 4: stick or twist? A review of asthma therapy

Many people with asthma do not achieve disease control, despite bronchodilators and inhaled corticosteroid therapy. People with uncontrolled asthma are at higher risk of an asthma attack and death, with mortality rates estimated at 1000 deaths/year in England and Wales. The recent National Review of Asthma Deaths (NRAD) report, ‘Why asthma still kills’, recommended that patients at step 4 or 5 of the British Thoracic Society/Scottish Intercollegiate Guidelines Network (BTS/SIGN) guidance must be referred to a specialist asthma service. This article reviews the 2014 evidence base for therapy of asthma patients at BTS/SIGN step 4 of the treatment cascade, in response to key findings of the NRAD report and lack of preferred treatment option at this step.

Surgical Repair of Mitral Valve Disease in Children: Perioperative Changes in Respiratory Function

OBJECTIVE

To assess the profile of changes in airway and respiratory tissue mechanics within a follow-up study performed in children with mitral valve disease, before and after surgical valve repair.

DESIGN

Perioperative measurements in a prospective, consecutive cross-sectional study.

SETTING

University hospital, tertiary care teaching hospital

PARTICIPANTS

The study comprised 24 children with congenital or post-rheumatic mitral valve insufficiency.

INTERVENTIONS

Input impedance of the respiratory system during spontaneous breathing was measured before and 5 days and 3 weeks after mitral valve surgery. In addition, airway and respiratory tissue mechanics and pulmonary arterial pressure were assessed with the patient under general anesthesia preoperatively and immediately postoperatively. Respiratory tissue elastance and changes in airway measurements were estimated from forced oscillatory impedance data by fitting an appropriate model.

MEASUREMENT AND MAIN RESULTS

Relating airway and respiratory tissue mechanics to previously established reference values obtained in age-matched healthy control patients revealed abnormal respiratory function (135±6.2% and 148±13% in respiratory elastance and resistance, respectively; p<0.001). Improvement in the airway properties was observed immediately after surgery (-15.2±3.4%; p<0.005) and lasted for the study period (-19±4.1%; p<0.001). Respiratory tissue elastance, which correlated preoperatively to the diastolic pulmonary arterial pressure, decreased only 5 days postoperatively (-20.6±4.1%; p<0.005). However, there was no evidence of a clear, immediate effect of surgery on the tissue mechanical parameters measured intraoperatively despite a decrease in diastolic pulmonary pressure.

CONCLUSIONS

Mitral valve disease in children leads to abnormal airway and respiratory tissue mechanics. Even though surgical repair of mitral insufficiency alleviates abnormal airway function, residual lung tissue stiffening may persist even weeks after the surgery, contributing to a sustained impairment in lung function.

Bronchoprotection and bronchorelaxation in asthma: New targets, and new ways to target the old ones

Despite over 50years of inhaled beta-agonists and corticosteroids as the default management or rescue drugs for asthma, recent research suggests that new therapeutic options are likely to emerge. This belief stems from both an improved understanding of what causes and regulates airway smooth muscle (ASM) contraction, and the identification of new targets whose inhibition or activation can relax ASM. In this review we discuss the recent findings that provide new insight into ASM contractile regulation, a revolution in pharmacology that identifies new ways to "tune" G protein-coupled receptors to improve therapeutic efficacy, and the discovery of several novel targets/approaches capable of effecting bronchoprotection or bronchodilation.

Characterization of Troponin Responses in Isoproterenol-Induced Cardiac Injury in the Hanover Wistar Rat

The investigations aimed to evaluate the usefulness of cardiac troponins as biomarkers of acute myocardial injury in the rat. Serum from female Hanover Wistar rats treated with a single intraperitoneal (IP) injection of isoproterenol (ISO) was assayed for cardiac troponin I (cTnI) (ACS: 180SE, Bayer), cTnI (Immulite 2000, Diagnostic Products Corporation) and cardiac troponin T (cTnT) (Elecsys 2010, Roche). In a time-course study (50.0 mg/kg ISO), serum cTnI (ACS:180SE) and cTnT increased above control levels at 1 hour postdosing, peaking at 2 hours (cTnI, 4.30 μg/L; cTnT, 1.79 μg/L), and declined to baseline by 48 hours, with histologic cardiac lesions first seen at 4 hours postdosing. The Immulite 2000 assay gave minimal cTnI signals, indicating poor immunoreactivity towards rat cTnI. In a dose-response study (0.25 to 20.0 mg/kg ISO), there was a trend for increasing cTnI (ACS:180SE) values with increasing ISO dose levels at 2 hours postdosing. By 24 hours, cTnI levels returned to baseline although chronic cardiac myodegeneration was present. We conclude that serum cTnI and cTnT levels are sensitive and specific biomarkers for detecting ISO induced myocardial injury in the rat. Serum troponin values reflect the development of histopathologic lesions; however peak troponin levels precede maximal lesion severity.

Overview of the Anatomy, Physiology, and Pharmacology of the Autonomic Nervous System

Comprised of the sympathetic nervous system, parasympathetic nervous system, and enteric nervous system, the autonomic nervous system (ANS) provides the neural control of all parts of the body except for skeletal muscles. The ANS has the major responsibility to ensure that the physiological integrity of cells, tissues, and organs throughout the entire body is maintained (homeostasis) in the face of perturbations exerted by both the external and internal environments. Many commonly prescribed drugs, over-the-counter drugs, toxins, and toxicants function by altering transmission within the ANS. Autonomic dysfunction is a signature of many neurological diseases or disorders. Despite the physiological relevance of the ANS, most neuroscience textbooks offer very limited coverage of this portion of the nervous system. This review article provides both historical and current information about the anatomy, physiology, and pharmacology of the sympathetic and parasympathetic divisions of the ANS. The ultimate aim is for this article to be a valuable resource for those interested in learning the basics of these two components of the ANS and to appreciate its importance in both health and disease. Other resources should be consulted for a thorough understanding of the third division of the ANS, the enteric nervous system. © 2016 American Physiological Society. Compr Physiol 6:1239-1278, 2016.

PI3K and ERK1/2 kinase inhibition potentiate protease inhibitor to attenuate allergen induced Th2 immune response in mouse

Proteases affect immune response by activating PI3K, ERK1/2 and p38 kinase. In present study, therapeutic effect of PI3K, ERK1/2 and p38 kinase inhibitor in combination with serine protease inhibitor was evaluated in cockroach extract (CE) induced airway inflammatory disease. Mice were sensitized on day 0, 7 and 14 and challenged on day 27, 28 and 29 with CE. Mice were given PI3K, ERK1/2 and the p38 kinase inhibitor (iPI3K, iERK1/2 and the ip38) alone or with serine protease inhibitor 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF), 1h before challenge. On day 30 airway resistance of mice were determined and euthanized to collect blood, BAL fluid and lung for analysis. CE immunized mice showed PI3K, ERK1/2 and p38 kinase activation, increased airway resistance, cellular infiltration, Th2 cytokines IgE and IgG1. AEBSF given to mice reduced the CE induced allergic response. AEBSF given in combination of iPI3K/iERK1/2 reduced cellular infiltration in lungs. Furthermore, iPI3K/iERK1/2 with AEBSF significantly reduced the CE induced Th2 cytokines in comparison to monotherapy of kinase inhibitor and AEBSF (P<0.05). The combination of iPI3K/iERK1/2 with AEBSF enhanced IL-12 level that could further provide a mean of Th2 reduction. Best effect in reduction of allergic response in mice was observed on administration of AEBSF with iPI3K. Conclusively, the combination of PI3K kinase inhibitor with AEBSF reduced allergen induced airway response and has therapeutic potential for add-on therapy in allergic airway disease.

Resolution of Rac-Bambuterol via Diastereoisomeric Salt Formation with o-Chloromandelic Acid and Differences in the Enantiomers' Pharmacodynamical Effects in Guinea Pigs and Beagles

In this study an enantioseparation method for rac-bambuterol (5-(2-(tert-butylamino)-1-hydroxyethyl)-1,3-phenylene bis(dimethylcarbamate)) via diastereoisomeric salt formation with o-chloromandelic acid was developed. The enantiomeric excess (ee) values and chemical purities of the desired products were confirmed by high-performance liquid chromatography (HPLC) using chiral stationary phase and reverse-phase HPLC analyses, respectively. The ee values and the chemical purities both exceeded 99%. Animal experiments showed that (R)-bambuterol was a potent inhibitor for histamine-induced asthma reactions. (S)-bambuterol was ineffective in relaxing the airways. Both enantiomers increased heart rates in beagles. Therefore, replacing rac-bambuterol with (R)-bambuterol could be beneficial for asthma patients.

Development of a Efficient and Sensitive Dispersive Liquid-Liquid Microextraction Technique for Extraction and Preconcentration of 10 β2-Agonists in Animal Urine

Dispersive liquid–liquid microextraction (DLLME) coupled with ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) was developed for the extraction and determination of 10 β₂-agonists in animal urine. Some experimental parameters, such as the type and volume of the extraction solvent, the concentration of the dispersant, the salt concentration, the pH value of the sample solution, the extraction time and the speed of centrifugation, were investigated and optimized. Under the optimized conditions, a good enrichment factors (4.8 to 32.3) were obtained for the extraction. The enrichment factor show that the concentration rate of DLLME is significantly higher than other pretreatment methods, and the detection sensitivity has been greatly improved. The calibration curves were linear, the correlation coefficient ranged from 0.9928 to 0.9999 for the concentration range of 0.05 to 50 ngmL^-1 and 0.1 to 50 ngmL^-1, and the relative standard deviations (RSDs, n = 15, intra and inter-day precision) at a concentration of 5 ngmL^-1 were in the range of 1.8 to 14.6%. The limits of detection (LODs) for the 10 β₂-agonists, based on a signal-to-noise ratio (S/N) of 3, were in the range of 0.01 to 0.03 ngmL^-1. The proposed method was used to identify β₂-agonists in three types of animal urine (swine, cattle, sheep), and the relative recoveries from each matrix were in the range of 89.2 to 106.8%, 90.0 to 109.8% and 89.2 to 107.2%, respectively.

Identification and Functional Characterization of Cis-Regulatory Elements Controlling Expression of the Porcine ADRB2 Gene

The beta-2 adrenergic receptor (beta-2 AR) modulates metabolic processes in skeletal muscle, liver, and adipose tissue in response to catecholamine stimulation. We showed previously that expression of the porcine beta-2 AR gene (ADRB2) is affected by cis-regulatory polymorphisms. These are most likely responsible for the association of ADRB2 with economically relevant muscle-related traits in pigs. The present study focused on characterization of promoter elements involved in basal transcriptional regulation of the porcine ADRB2 in different cell types to aid identification of its cis-regulatory polymorphisms. Based on in silico analysis, luciferase reporter gene assays and gel shift assays were performed using COS-7, HepG2, C2C12, and 3T3-L1 cells. Deletion mapping of the 5´ flanking region (-1324 to +33) of ADRB2 revealed the region between -307 and -269 to be the minimal promoter, including regulatory elements essential for the basal transcriptional activity in all four tested cell types. Directly upstream (-400 to -323) we identified an important enhancer element required for maximal promoter activity. In silico analysis and gel shift assays revealed that this GC-rich element harbors two evolutionarily conserved binding sites of Sp1, a constitutive transcriptional activator. Significant transcriptional activation of the porcine ADRB2 promoter was demonstrated by overexpression of Sp1. Our results demonstrate, for the first time, an important role of Sp1 and of the responsive enhancer element in the regulation of ADRB2 expression. Polymorphisms located in this domain of the porcine ADRB2 promoter represent candidate causal cis-regulatory variants.

Epithelial function and dysfunction in asthma

Asthma was previously defined as an allergic Th2-mediated inflammatory immune disorder. Recently, this paradigm has been challenged because not all pathological changes observed in the asthmatic airways are adequately explained simply as a result of Th2-mediated processes. Contemporary thought holds that asthma is a complex immune disorder involving innate as well as adaptive immune responses, with the clinical heterogeneity of asthma perhaps a result of the different relative contribution of these two systems to the disease. Epidemiological studies show that exposure to certain environmental substances is strongly associated with the risk of developing asthma. The airway epithelium is first barrier to interact with, and respond to, environmental agents (pollution, viral infection, allergens), suggesting that it is a key player in the pathology of asthma. Epithelial cells play a key role in the regulation of tissue homeostasis by the modulation of numerous molecules, from antioxidants and lipid mediators to growth factors, cytokines, and chemokines. Additionally, the epithelium is also able to suppress mechanisms involved in, for example, inflammation in order to maintain homeostasis. An intrinsic alteration or defect in these regulation mechanisms compromises the epithelial barrier, and therefore, the barrier may be more prone to environmental substances and thus more likely to exhibit an asthmatic phenotype. In support of this, polymorphisms in a number of genes that are expressed in the bronchial epithelium have been linked to asthma susceptibility, while environmental factors may affect epigenetic mechanisms that can alter epithelial function and response to environmental insults. A detailed understanding of the regulatory role of the airway epithelium is required to develop new therapeutic strategies for asthma that not only address the symptoms but also the underlining pathogenic mechanism(s) and prevent airway remodelling.

Turning a molecule into a medicine: the development of indacaterol as a novel once-daily bronchodilator treatment for patients with COPD

Indacaterol is the first once-daily, long-acting β2-adrenergic agonist (LABA) approved for the treatment of chronic obstructive pulmonary disease (COPD). Indacaterol was developed using a combination of informed drug design and molecular chemistry to generate a β2-adrenergic agonist with a fast onset and long duration of action, enabling once-daily dosing with an acceptable safety profile. Early preclinical studies with indacaterol demonstrated these characteristics, and this promising molecule was taken into clinical development, originally for asthma treatment. Subsequent safety concerns over LABA monotherapy in patients with asthma redirected indacaterol's development to centre on COPD, where a good evidence base and guideline recommendations for bronchodilator monotherapy existed. Clinical development was initially complicated by different inhaler devices and differing doses of indacaterol. Using a phase III innovative adaptive-design clinical trial (INHANCE), indacaterol 150 and 300 μg once-daily doses were selected to be taken forward into the phase III INERGIZE programme. This programme delivered placebo-controlled and active-comparator data, including comparisons with formoterol, tiotropium and salmeterol/fluticasone, as well as the use of indacaterol in combination with tiotropium. Together, these studies provided a comprehensive assessment of the benefit-risk profile of indacaterol, allowing for regulatory submission. Indacaterol was first approved at once-daily doses of 150 and 300 μg in the European Union in 2009, followed by 150 µg in Japan (2011) and China (2012), and 75 μg in the United States (2011). To date, indacaterol is approved and marketed in more than 100 countries worldwide for once-daily maintenance treatment of COPD.

In vitro comparison of duration of action of melatonin agonists on melatonin MT1 receptor: possible link between duration of action and dissociation rate from receptor

Melatonin MT1 and MT2 receptors are Gi protein-coupled receptors and promising therapeutic targets for a number of diseases. A proportion of G protein-coupled receptor agonists and antagonists have been classified according to their duration of action, which influences their pharmacological efficacy. However, the duration of action of melatonin agonists remains unclear. In this study, we investigated the duration of action of melatonin agonists (melatonin, 2-iodomelatonin, ramelteon, and the ramelteon metabolite M-II) at the melatonin MT1 receptor, which is more resistant to agonist-induced desensitization than the melatonin MT2 receptor. In Chinese hamster ovary cells stably expressing the human melatonin MT1 receptor, significant differences in the duration of action were observed after 2-h pretreatment with agonists followed by washout. In contrast to melatonin and M-II, the agonist activities of ramelteon and 2-iodomelatonin were persistent (i.e. inhibition of forskolin-stimulated cAMP formation and increase in ERK 1/2 phosphorylation) even after repeated washouts. Similar activities were observed for INS-1 cells endogenously expressing the rat MT1 receptor. Further, we examined potential factors linked to the duration of action. Residual activities of melatonin agonists after washout strongly correlated with their dissociation rates from the human melatonin MT1 receptor, but not their lipophilicity or extent of desensitization. These data suggest that the in vitro duration of action significantly differs between melatonin agonists and might dictate dissociation kinetics. Characterization of these in vitro properties may facilitate further in vivo study of the duration of action.

Salmeterol's extreme β2 selectivity is due to residues in both extracellular loops and transmembrane domains

Salmeterol is a long-acting β2-agonist, widely used as an inhaled treatment of asthma and chronic obstructive pulmonary disease. It has very high β2-affinity (log KD -8.95) and is very selective for the β2-adrenoceptor (1000-fold selectivity over the β1-adrenoceptor). This study used a mutagenesis approach to determine the exact amino acids in the human β2-adrenoceptor responsible for this very high selectivity. Wild-type β2- and β1-adrenoceptors, chimeric β2/β1-adrenoceptors, and receptors with single-point mutations were transfected into Chinese hamster ovary-K1 cells, and affinity and function were studied using [(3)H]CGP 12177 [(-)-4-(3-tert-butylamino-2-hydroxypropoxy)-benzimidazol-2-one] whole-cell binding and [(3)H]cAMP accumulation. Extracellular loop 3 (and specifically amino acid K305) had the largest single effect by reducing salmeterol's affinity for the β2-adrenoceptor by 31-fold. H296 in transmembrane 6 also had a major effect (18-fold reduction in salmeterol affinity). Combining these, in the double mutant β2-H296K-K305D, reduced salmeterol's affinity by 275-fold, to within 4-fold of that of the β1-adrenoceptor, without affecting the affinity or selectivity of other β2-agonists (salbutamol, formoterol, fenoterol, clenbuterol, or adrenaline). Another important amino acid was Y308 in transmembrane 7, although this also affected the affinity and selectivity of other agonists. F194 in extracellular loop 2 and R304 in extracellular loop 3 also had minor effects. None of these mutations (including the double mutant β2-H296K-K305D) affected the efficacy or duration of action of salmeterol. This suggests that the high affinity and selectivity of salmeterol are due to specific amino acids within the receptor itself, but that the duration of action is at least in part due to other factors, for example lipophilicity.

Eosinophils in the lung - modulating apoptosis and efferocytosis in airway inflammation

Due to the key role of the lung in efficient transfer of oxygen in exchange for carbon dioxide, a controlled inflammatory response is essential for restoration of tissue homeostasis following airway exposure to bacterial pathogens or environmental toxins. Unregulated or prolonged inflammatory responses in the lungs can lead to tissue damage, disrupting normal tissue architecture, and consequently compromising efficient gaseous exchange. Failure to resolve inflammation underlies the development and/or progression of a number of inflammatory lung diseases including asthma. Eosinophils, granulocytic cells of the innate immune system, are primarily involved in defense against parasitic infections. However, the propagation of the allergic inflammatory response in chronic asthma is thought to involve excessive recruitment and impaired apoptosis of eosinophils together with defective phagocytic clearance of apoptotic cells (efferocytosis). In terms of therapeutic approaches for the treatment of asthma, the widespread use of glucocorticoids is associated with a number of adverse health consequences after long-term use, while some patients suffer from steroid-resistant disease. A new approach for therapeutic intervention would be to promote the resolution of inflammation via modulation of eosinophil apoptosis and the phagocytic clearance of apoptotic cells. This review focuses on the mechanisms underpinning eosinophil-mediated lung damage, currently available treatments and therapeutic targets that might in future be harnessed to facilitate inflammation resolution by the manipulation of cell survival and clearance pathways.

An optical multi-sensing system for detection of cardiovascular toxicity

A mini-microscope-based system for multisite detection of cardiovascular toxicity was developed. The mini-microscope consisted of an image sensor and lens module extracted from an inexpensive webcam. The flipped lens module enabled cells to be magnified and monitored during testing. The portability and compactness of this system enables short-term and potential long-term experimentation inside a conventional incubator. The toxicity test results demonstrated that the normalized beating rates of cardiac muscle cells selected from multiple regions increased over time when treated with 100 nM isoprenaline. The presented system could be a promising cost-effective cell-based testing tool for discovering and screening drugs.

Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations

An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 μm column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively.