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The European Respiratory Journal May 2017This international task force report updates general considerations for bronchial challenge testing and the performance of the methacholine challenge test. There are...
This international task force report updates general considerations for bronchial challenge testing and the performance of the methacholine challenge test. There are notable changes from prior recommendations in order to accommodate newer delivery devices. Rather than basing the test result upon a methacholine concentration (provocative concentration (PC) causing a 20% fall in forced expiratory volume in 1 s (FEV)), the new recommendations base the result upon the delivered dose of methacholine causing a 20% fall in FEV (provocative dose (PD)). This end-point allows comparable results from different devices or protocols, thus any suitable nebuliser or dosimeter may be used, so long as the delivery characteristics are known. Inhalation may be by tidal breathing using a breath-actuated or continuous nebuliser for 1 min (or more), or by a dosimeter with a suitable breath count. Tests requiring maximal inhalations to total lung capacity are not recommended because the bronchoprotective effect of a deep breath reduces the sensitivity of the test.
Topics: Administration, Inhalation; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Dose-Response Relationship, Drug; Europe; Forced Expiratory Volume; Humans; Methacholine Chloride; Nebulizers and Vaporizers; Practice Guidelines as Topic; Societies, Medical; Total Lung Capacity
PubMed: 28461290
DOI: 10.1183/13993003.01526-2016 -
PloS One 2023People experiencing asthma exacerbations are at increased risk of cardiovascular events. To better understand the relationship between asthma exacerbations and... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
People experiencing asthma exacerbations are at increased risk of cardiovascular events. To better understand the relationship between asthma exacerbations and cardiovascular risk, this randomized case-control, cross-over controlled trial assessed the immediate systemic inflammatory and vascular responses to acutely induced pulmonary inflammation and bronchoconstriction in people with asthma and controls.
METHODS
Twenty-six people with asthma and 25 controls underwent three airway challenges (placebo, mannitol, and methacholine) in random order. Markers of cardiovascular risk, including serum C-reactive protein, interleukin-6, and tumor necrosis factor, endothelial function (flow-mediated dilation), microvascular function (blood-flow following reactive hyperemia), and arterial stiffness (pulse wave velocity) were evaluated at baseline and within one hour following each challenge. The systemic responses in a) asthma/control and b) positive airway challenges were analyzed. (ClinicalTrials.gov reg# NCT02630511).
RESULTS
Both the mannitol and methacholine challenges resulted in clinically significant reductions in forced expiratory volume in 1 second (FEV1) in asthma (-7.6% and -17.9%, respectively). Following positive challenges, reduction in FEV1 was -27.6% for methacholine and -14.2% for mannitol. No meaningful differences in predictors of cardiovascular risk were observed between airway challenges regardless of bronchoconstrictor response.
CONCLUSION
Neither acutely induced bronchoconstriction nor pulmonary inflammation and bronchoconstriction resulted in meaningful changes in systemic inflammatory or vascular function. These findings question whether the increased cardiovascular risk associated with asthma exacerbations is secondary to acute bronchoconstriction or inflammation, and suggest that other factors need to be further evaluated such as the cardiovascular impacts of short-acting inhaled beta-agonists.
Topics: Humans; Methacholine Chloride; Cardiovascular Diseases; Pulse Wave Analysis; Risk Factors; Asthma; Bronchoconstriction; Bronchial Provocation Tests; Forced Expiratory Volume
PubMed: 37459335
DOI: 10.1371/journal.pone.0288623 -
The Journal of Allergy and Clinical... Nov 2023The emerging role of sphingosine-1-phosphate (S1P) in regulating smooth muscle functions has led to the exploration of the possibility that this sphingolipid could...
BACKGROUND
The emerging role of sphingosine-1-phosphate (S1P) in regulating smooth muscle functions has led to the exploration of the possibility that this sphingolipid could represent a potential therapeutic target in asthma and other lung diseases. Several studies in animal surrogates have suggested a role for S1P-mediated signaling in the regulation of airway smooth muscle (ASM) contraction, airway hyperresponsiveness, and airway remodeling, but evidence from human studies is lacking.
OBJECTIVE
We sought to compare the responsiveness of the airways to S1P in healthy and asthmatic individuals in vivo, in isolated human airways ex vivo, and in murine airways dissected from healthy and house dust mite (HDM)-sensitized animals.
METHODS
Airway responsiveness was measured by spirometry during inhalation challenges and by wire myography in airways isolated from human and mouse lungs. Thymidine incorporation and calcium mobilization assays were used to study human ASM cell responses.
RESULTS
S1P did not induce contraction of airways isolated from healthy and HDM-exposed mice, nor in human airways. Similarly, there was no airway constriction observed in healthy and asthmatic subjects in response to increasing concentrations of inhaled S1P. However, a 30-minute exposure to S1P induced a significant concentration-dependent enhancement of airway reactivity to methacholine and to histamine in murine and human airways, respectively. HDM-sensitized mice demonstrated a significant increase in methacholine responsiveness, which was not further enhanced by S1P treatment. S1P also concentration-dependently enhanced proliferation of human ASM cells, an effect mediated through S1P receptor type 2, as shown by selective antagonism and S1P receptor type 2 small-interfering RNA knockdown.
CONCLUSIONS
Our data suggest that S1P released locally into the airways may be involved in the regulation of ASM hyperresponsiveness and hyperplasia, defining a novel target for future therapies.
Topics: Humans; Mice; Animals; Sphingosine-1-Phosphate Receptors; Methacholine Chloride; Asthma; Muscle, Smooth; Cell Proliferation
PubMed: 37474025
DOI: 10.1016/j.jaci.2023.05.028 -
Journal of Applied Physiology... Jul 2022Mice are a valuable model for elegant studies of complex, system-dependent diseases, including pulmonary diseases. Current tools to assess lung function in mice are...
Mice are a valuable model for elegant studies of complex, system-dependent diseases, including pulmonary diseases. Current tools to assess lung function in mice are either terminal or lack accuracy. We set out to develop a low-cost, accurate, head-out variable-pressure plethysmography system to allow for repeated, nonterminal measurements of lung function in mice. Current head-out plethysmography systems are limited by air leaks that prevent accurate measures of volume and flow. We designed an inflatable cuff that encompasses the mouse's neck preventing air leak. We wrote corresponding software to collect and analyze the data, remove movement artifacts, and automatically calibrate each dataset. This software calculates volume, inspiratory/expiratory time, breaths per minute, mid-expiratory flow, and end-inspiratory pause. To validate the use, we established that our plethysmography system accurately measured tidal breathing, the bronchoconstrictive response to methacholine, sex- and age-associated changes in breathing, and breathing changes associated with house dust mite sensitization. Our estimates of volume, flow, and timing of breaths are in line with published estimates, we observed dose-dependent decreases in volume and flow in response to methacholine ( < 0.05), increased lung volume, and decreased breathing rate with aging ( < 0.05), and that house dust mite sensitization decreased volume and flow ( < 0.05) while exacerbating the methacholine-induced increase in inspiratory time ( < 0.05). We describe an accurate, sensitive, low-cost, head-out plethysmography system that allows for longitudinal studies of pulmonary disease in mice. We describe a low-cost, variable-pressure head-out plethysmography system that can be used to assess lung function in mice. A balloon cuff is inflated around the mouse's neck to prevent air leak, allowing for accurate measurements of lung volume and air flow. Custom software facilitates system calibration, removes movement artifacts, and eases data analysis. The system was validated by measuring tidal breathing, responses to methacholine, and changes associated with house dust mite sensitization, sex, and aging.
Topics: Animals; Bronchoconstriction; Lung; Lung Volume Measurements; Methacholine Chloride; Mice; Plethysmography; Tidal Volume
PubMed: 35608203
DOI: 10.1152/japplphysiol.00835.2021 -
Respiratory Research Oct 2023The standard therapy for bronchial asthma consists of combinations of acute (short-acting ß-sympathomimetics) and, depending on the severity of disease, additional...
INTRODUCTION
The standard therapy for bronchial asthma consists of combinations of acute (short-acting ß-sympathomimetics) and, depending on the severity of disease, additional long-term treatment (including inhaled glucocorticoids, long-acting ß-sympathomimetics, anticholinergics, anti-IL-4R antibodies). The antidepressant amitriptyline has been identified as a relevant down-regulator of immunological T2-phenotype in asthma, acting-at least partially-through inhibition of acid sphingomyelinase (ASM), an enzyme involved in sphingolipid metabolism. Here, we investigated the non-immunological role of amitriptyline on acute bronchoconstriction, a main feature of airway hyperresponsiveness in asthmatic disease.
METHODS
After stimulation of precision cut lung slices (PCLS) from mice (wildtype and ASM-knockout), rats, guinea pigs and human lungs with mediators of bronchoconstriction (endogenous and exogenous acetylcholine, methacholine, serotonin, endothelin, histamine, thromboxane-receptor agonist U46619 and leukotriene LTD4, airway area was monitored in the absence of or with rising concentrations of amitriptyline. Airway dilatation was also investigated in rat PCLS by prior contraction induced by methacholine. As bronchodilators for maximal relaxation, we used IBMX (PDE inhibitor) and salbutamol (ß-adrenergic agonist) and compared these effects with the impact of amitriptyline treatment. Isolated perfused lungs (IPL) of wildtype mice were treated with amitriptyline, administered via the vascular system (perfusate) or intratracheally as an inhalation. To this end, amitriptyline was nebulized via pariboy in-vivo and mice were ventilated with the flexiVent setup immediately after inhalation of amitriptyline with monitoring of lung function.
RESULTS
Our results show amitriptyline to be a potential inhibitor of bronchoconstriction, induced by exogenous or endogenous (EFS) acetylcholine, serotonin and histamine, in PCLS from various species. The effects of endothelin, thromboxane and leukotrienes could not be blocked. In acute bronchoconstriction, amitriptyline seems to act ASM-independent, because ASM-deficiency (Smdp1) did not change the effect of acetylcholine on airway contraction. Systemic as well as inhaled amitriptyline ameliorated the resistance of IPL after acetylcholine provocation. With the flexiVent setup, we demonstrated that the acetylcholine-induced rise in central and tissue resistance was much more marked in untreated animals than in amitriptyline-treated ones. Additionally, we provide clear evidence that amitriptyline dilatates pre-contracted airways as effectively as a combination of typical bronchodilators such as IBMX and salbutamol.
CONCLUSION
Amitriptyline is a drug of high potential, which inhibits acute bronchoconstriction and induces bronchodilatation in pre-contracted airways. It could be one of the first therapeutic agents in asthmatic disease to have powerful effects on the T2-allergic phenotype and on acute airway hyperresponsiveness with bronchoconstriction, especially when inhaled.
Topics: Mice; Rats; Humans; Animals; Guinea Pigs; Bronchoconstriction; Methacholine Chloride; Amitriptyline; Histamine; Bronchodilator Agents; Serotonin; Acetylcholine; Sympathomimetics; 1-Methyl-3-isobutylxanthine; Dilatation; Lung; Asthma; Albuterol; Endothelins; Thromboxanes
PubMed: 37907918
DOI: 10.1186/s12931-023-02580-6 -
Experimental Lung Research 2023Force adaptation is a process whereby the contractile capacity of the airway smooth muscle increases during a sustained contraction (aka tone). Tone also increases the...
Force adaptation is a process whereby the contractile capacity of the airway smooth muscle increases during a sustained contraction (aka tone). Tone also increases the response to a nebulized challenge with methacholine , presumably through force adaptation. Yet, due to its patchy pattern of deposition, nebulized methacholine often spurs small airway narrowing heterogeneity and closure, two important enhancers of the methacholine response. This raises the possibility that the potentiating effect of tone on the methacholine response is not due to force adaptation but by furthering heterogeneity and closure. Herein, methacholine was delivered homogenously through the intravenous (i.v.) route. Female and male BALB/c mice were subjected to one of two i.v. methacholine challenges, each of the same cumulative dose but starting by a 20-min period either with or without tone induced by serial i.v. boluses. Changes in respiratory mechanics were monitored throughout by oscillometry, and the response after the final dose was compared between the two challenges to assess the effect of tone. For the elastance of the respiratory system (E), tone potentiated the methacholine response by 64 and 405% in females (37.4 ± 10.7 61.5 ± 15.1 cmHO/mL; = 0.01) and males (33.0 ± 14.3 166.7 ± 60.6 cmHO/mL; = 0.0004), respectively. For the resistance of the respiratory system (R), tone potentiated the methacholine response by 129 and 225% in females (9.7 ± 3.5 22.2 ± 4.3 cmHO·s/mL; = 0.0003) and males (10.7 ± 3.1 34.7 ± 7.9 cmHO·s/mL; < 0.0001), respectively. As previously reported with nebulized challenges, tone increases the response to i.v. methacholine in both sexes; albeit sexual dimorphisms were obvious regarding the relative resistive elastic nature of this potentiation. This represents further support that tone increases the lung response to methacholine through force adaptation.
Topics: Male; Female; Animals; Mice; Methacholine Chloride; Lung; Respiratory Mechanics; Bronchial Provocation Tests; Airway Resistance
PubMed: 37477352
DOI: 10.1080/01902148.2023.2237127 -
The Journal of Clinical Investigation Sep 2023Asthma is a chronic inflammatory disease associated with episodic airway narrowing. Inhaled β2-adrenergic receptor (β2AR) agonists (β2-agonists) promote - with...
Asthma is a chronic inflammatory disease associated with episodic airway narrowing. Inhaled β2-adrenergic receptor (β2AR) agonists (β2-agonists) promote - with limited efficacy - bronchodilation in asthma. All β2-agonists are canonical orthosteric ligands that bind the same site as endogenous epinephrine. We recently isolated a β2AR-selective positive allosteric modulator (PAM), compound-6 (Cmpd-6), which binds outside of the orthosteric site and modulates orthosteric ligand functions. With the emerging therapeutic potential of G-protein coupled receptor allosteric ligands, we investigated the impact of Cmpd-6 on β2AR-mediated bronchoprotection. Consistent with our findings using human β2ARs, Cmpd-6 allosterically potentiated β2-agonist binding to guinea pig β2ARs and downstream signaling of β2ARs. In contrast, Cmpd-6 had no such effect on murine β2ARs, which lack a crucial amino acid in the Cmpd-6 allosteric binding site. Importantly, Cmpd-6 enhanced β2 agonist-mediated bronchoprotection against methacholine-induced bronchoconstriction in guinea pig lung slices, but - in line with the binding studies - not in mice. Moreover, Cmpd-6 robustly potentiated β2 agonist-mediated bronchoprotection against allergen-induced airway constriction in lung slices obtained from a guinea pig model of allergic asthma. Cmpd-6 similarly enhanced β2 agonist-mediated bronchoprotection against methacholine-induced bronchoconstriction in human lung slices. Our results highlight the potential of β2AR-selective PAMs in the treatment of airway narrowing in asthma and other obstructive respiratory diseases.
Topics: Humans; Mice; Animals; Guinea Pigs; Methacholine Chloride; Ligands; Asthma; Lung; Binding Sites; Receptors, Adrenergic, beta-2
PubMed: 37432742
DOI: 10.1172/JCI167337 -
American Journal of Respiratory Cell... Nov 2020Impaired sphingolipid synthesis is linked genetically to childhood asthma and functionally to airway hyperreactivity (AHR). The objective was to investigate whether...
Impaired sphingolipid synthesis is linked genetically to childhood asthma and functionally to airway hyperreactivity (AHR). The objective was to investigate whether sphingolipid synthesis could be a target for asthma therapeutics. The effects of GlyH-101 and fenretinide via modulation of sphingolipid synthesis on AHR was evaluated in mice deficient in SPT (serine palmitoyl-CoA transferase), the rate-limiting enzyme of sphingolipid synthesis. The drugs were also used directly in human airway smooth-muscle and epithelial cells to evaluate changes in sphingolipid metabolites and calcium release. GlyH-101 and fenretinide increased sphinganine and dihydroceramides ( sphingolipid metabolites) in lung epithelial and airway smooth-muscle cells, decreased the intracellular calcium concentration in airway smooth-muscle cells, and decreased agonist-induced contraction in proximal and peripheral airways. GlyH-101 also decreased AHR in SPT-deficient mice . This study identifies the manipulation of sphingolipid synthesis as a novel metabolic therapeutic strategy to alleviate AHR.
Topics: Alveolar Epithelial Cells; Bradykinin; Bronchial Hyperreactivity; Calcium; Calcium Signaling; Fenretinide; Glycine; Humans; Hydrazines; Metabolome; Methacholine Chloride; Muscle Contraction; Serine C-Palmitoyltransferase; Sphingolipids
PubMed: 32706610
DOI: 10.1165/rcmb.2020-0194OC -
Respiratory Research Jul 2023Accumulating clinical evidence links Obstructive Sleep Apnea (OSA) with worse outcomes of asthma, but impact on airway function remains sparsely studied. We tested...
INTRODUCTION
Accumulating clinical evidence links Obstructive Sleep Apnea (OSA) with worse outcomes of asthma, but impact on airway function remains sparsely studied. We tested effects of Chronic Intermittent Hypoxia (CIH) - a hallmark of OSA - on airway hyperresponsiveness (AHR), in a rat model of chronic allergen-induced inflammation.
METHODS
Brown Norway rats were exposed to six weeks of CIH or normoxia (NORM) concurrent with weekly house dust mites (HDM) or saline (SAL) challenges. At endpoint, we assessed responses to seven Methacholine (Mch) doses (0, 4, 8, 16, 32, 64, 128 mg/mL) on a FlexiVent system (Scireq). Maximal (or plateau) responses (reactivity) for total respiratory system Resistance (R) and Elastance (E), Newtonian airway resistance (R a measure of central airways function) and tissue damping (G, a measure of distal airways function) were plotted.
RESULTS
HDM/CIH-treated animals demonstrated the highest reactivity to Mch in R and E compared to all other groups (HDM/NORM, SAL/CIH and SAL/NORM p < 0.05 for all comparisons, for doses 5-7 for R, and for doses 4-7 for E). The enhanced R response was due to an increase in G (doses 4-7, p < 0.05 for comparisons to all other groups), whereas R was not affected by CIH.
CONCLUSIONS
In rats chronically challenged with HDM, concurrent CIH exposure induces AHR primarily in the distal airways, which affects the respiratory system frequency-dependent elastic properties.
Topics: Rats; Animals; Pyroglyphidae; Allergens; Respiratory Hypersensitivity; Lung; Hypoxia; Methacholine Chloride; Inflammation; Sleep Apnea, Obstructive; Disease Models, Animal
PubMed: 37468919
DOI: 10.1186/s12931-023-02493-4 -
Chest Apr 2023The purpose of this study was to investigate physiological phenotypes of asthma in obesity.
BACKGROUND
The purpose of this study was to investigate physiological phenotypes of asthma in obesity.
RESEARCH QUESTION
Do physiological responses during bronchoconstriction distinguish different groups of asthma in people with obesity, and also differentiate from responses simply related to obesity?
STUDY DESIGN AND METHODS
Cross-sectional study of people with obesity (31 with asthma and 22 without lung disease). Participants underwent methacholine challenge testing with measurement of spirometry and respiratory system impedance by oscillometry.
RESULTS
Participants had class III obesity (BMI, 46.7 ± 6.6 kg/m in control subjects and 47.2 ± 8.2 kg/m in people with asthma). Most participants had significant changes in peripheral airway impedance in response to methacholine: in control subjects, resistance at 5 Hz measured by oscillometry increased by 45% ± 27% and area under the reactance curve (AX) by 268% ± 236% in response to 16 mg/mL methacholine; in people with asthma, resistance at 5 Hz measured by oscillometry increased by 52% ± 38% and AX by 361% ± 295% in response to provocation concentration producing a 20% fall in FEV dose of methacholine. These responses suggest that obesity predisposes to peripheral airway reactivity. Two distinct groups of asthma emerged based on respiratory system impedance: one with lower reactance (baseline AX, 11.8; interquartile range, 9.9-23.4 cm HO/L) and more concordant bronchoconstriction in central and peripheral airways; the other with high reactance (baseline AX, 46.7; interquartile range, 23.2-53.7 cm HO/L) and discordant bronchoconstriction responses in central and peripheral airways. The high reactance asthma group included only women, and reported significantly more gastroesophageal reflux disease, worse chest tightness, more wheeze, and more asthma exacerbations than the low reactance group.
INTERPRETATION
Peripheral airway reactivity detected by oscillometry is common in obese control subjects and obese people with asthma. There is a subgroup of obese asthma characterized by significant peripheral airway dysfunction by oscillometry out of proportion to spirometric airway dysfunction. This peripheral dysfunction represents clinically significant respiratory disease not readily assessed by spirometry.
Topics: Female; Humans; Methacholine Chloride; Cross-Sectional Studies; Asthma; Respiratory System; Spirometry; Bronchial Provocation Tests; Obesity; Airway Resistance; Forced Expiratory Volume
PubMed: 36610669
DOI: 10.1016/j.chest.2022.12.030