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Biology of Sex Differences Jan 2023Asthma is a chronic airway condition that occurs more often in women than men during reproductive years. Population studies have collectively shown that long-term use of...
RATIONALE
Asthma is a chronic airway condition that occurs more often in women than men during reproductive years. Population studies have collectively shown that long-term use of oral contraceptives decreased the onset of asthma in women of reproductive age. In the current study, we hypothesized that steady-state levels of estrogen would reduce airway inflammation and airway hyperresponsiveness to methacholine challenge.
METHODS
Ovariectomized BALB/c mice (Ovx) were implanted with subcutaneous hormone pellets (estrogen, OVX-E2) that deliver consistent levels of estrogen [68 ± 2 pg/mL], or placebo pellets (OVX-Placebo), followed by ovalbumin sensitization and challenge. In conjunction with methacholine challenge, immune phenotyping was performed to correlate inflammatory proteins and immune populations with better or worse pulmonary outcomes measured by invasive pulmonary mechanics techniques.
RESULTS
Histologic analysis showed an increase in total cell infiltration and mucus staining around the airways leading to an increased inflammatory score in ovarectomized (OVX) animals with steady-state estrogen pellets (OVX-E2-OVA) as compared to other groups including female-sham operated (F-INTACT-OVA) and OVX implanted with a placebo pellet (OVX-Pl-OVA). Airway resistance (Rrs) and lung elastance (Ers) were increased in OVX-E2-OVA in comparison to F-INTACT-OVA following aerosolized intratracheal methacholine challenges. Immune phenotyping revealed that steady-state estrogen reduced CD3+ T cells, CD19+ B cells, ILC2 and eosinophils in the BAL across all experiments. While these commonly described allergic cells were reduced in the BAL, or airways, we found no changes in neutrophils, CD3+ T cells or CD19+ B cells in the remaining lung tissue. Similarly, inflammatory cytokines (IL-5 and IL-13) were also decreased in OVX-E2-OVA-treated animals in comparison to Female-INTACT-OVA mice in the BAL, but in the lung tissue IL-5, IL-13 and IL-33 were comparable in OVX-E2-OVA and F-INTACT OVA mice. ILC2 were sorted from the lungs and stimulated with exogenous IL-33. These ILC2 had reduced cytokine and chemokine expression when they were isolated from OVX-E2-OVA animals, indicating that steady-state estrogen suppresses IL-33-mediated activation of ILC2.
CONCLUSIONS
Therapeutically targeting estrogen receptors may have a limiting effect on eosinophils, ILC2 and potentially other immune populations that may improve asthma symptoms in those females that experience perimenstrual worsening of asthma, with the caveat, that long-term use of estrogens or hormone receptor modulators may be detrimental to the lung microenvironment over time.
Topics: Female; Animals; Mice; Interleukin-33; Estradiol; Immunity, Innate; Interleukin-13; Methacholine Chloride; Allergens; Airway Resistance; Interleukin-5; Bronchoalveolar Lavage Fluid; Lymphocytes; Lung; Asthma; Cytokines; Estrogens
PubMed: 36609358
DOI: 10.1186/s13293-022-00483-7 -
G3 (Bethesda, Md.) Sep 2016Allergic asthma is common airway disease that is characterized in part by enhanced airway constriction in response to nonspecific stimuli. Genome-wide association...
Allergic asthma is common airway disease that is characterized in part by enhanced airway constriction in response to nonspecific stimuli. Genome-wide association studies have identified multiple loci associated with asthma risk in humans, but these studies have not accounted for gene-environment interactions, which are thought to be important factors in asthma. To identify quantitative trait loci (QTL) that regulate responses to a common human allergen, we applied a house dust mite mouse (HDM) model of allergic airway disease (AAD) to 146 incipient lines of the Collaborative Cross (CC) and the CC founder strains. We employed a longitudinal study design in which mice were phenotyped for response to the bronchoconstrictor methacholine both before and after HDM sensitization and challenge using whole body plethysmography (WBP). There was significant variation in methacholine responsiveness due to both strain and HDM treatment, as reflected by changes in the WBP parameter enhanced pause. We also found that distinct QTL regulate baseline [chromosome (Chr) 18] and post-HDM (Chr 19) methacholine responsiveness and that post-HDM airway responsiveness was correlated with other features of AAD. Finally, using invasive measurements of airway mechanics, we tested whether the Chr 19 QTL affects lung resistance per se using C57BL/6J mice and a consomic strain but found that QTL haplotype did not affect lung resistance. We conclude that aspects of baseline and allergen-induced methacholine responsiveness are associated with genetic variation, and that robust detection of airway resistance QTL in genetically diverse mice will be facilitated by direct measurement of airway mechanics.
Topics: Allergens; Animals; Asthma; Disease Models, Animal; Gene-Environment Interaction; Humans; Hypersensitivity; Immunization; Lung; Methacholine Chloride; Mice; Plethysmography; Pyroglyphidae; Quantitative Trait Loci
PubMed: 27449512
DOI: 10.1534/g3.116.032912 -
Biochemical Pharmacology Sep 2020Demonstration of bronchial hyperresponsiveness is a key feature in asthma diagnosis. Methacholine challenge has proved to be a highly sensitive test to diagnose asthma...
Demonstration of bronchial hyperresponsiveness is a key feature in asthma diagnosis. Methacholine challenge has proved to be a highly sensitive test to diagnose asthma in patients with chronic respiratory symptoms and preserved baseline lung function (FEV1 > 70% pred.) but is time consuming and may sometimes reveal unpleasant to the patient. We conducted a retrospective study on 270 patients recruited from the University Asthma Clinic of Liege. We have compared the values of several lung function indices and fractional exhaled nitric oxide (FeNO) in predicting a provocative methacholine concentration ≤16 mg/ml on a discovery cohort of 129 patients (57 already on ICS) and on a validation cohort of 141 patients (66 already on ICS). In the discovery study (n = 129), 85 patients (66%) had a positive methacholine challenge with PC20M ≤ 16 mg/ml. Those patients had lower baseline % predicted FEV1 (92% vs. 100%; p < 0.01), lower FEV1/FVC ratio (79% vs. 82%; p < 0.05), higher RV/TLC ratio (114% vs. 100%; p < 0,0001), lower SGaw (specific conductance) (0.76 vs. 0.95; p < 0,001) and higher FeNO (29 ppb vs. 19 ppb; p < 0,01). When performing ROC curve the RV/TLC ratio provided the greatest AUC (0.74, p < 0.001), sGAW had intermediate AUC of 0.69 (p < 0.001) while FeNO, FEV1 and FEV1/FVC ratio were modestly predictive (AUC of 0.65 (p < 0.05), 0,67 (p < 0.001) and 0,63 (p < 0.001). These results were confirmed in the validation study (n = 141). Based on a logistic regression analysis, significant variables associated with positive methacholine challenge were FeNO and RV/TLC (% Pred). A combined application of FeNO and RV/TLC (% Pred) for predicting the PC20M had a specificity of 85%, a sensitivity of 59% and an AUC of 0.79. In the validation study, three variables (RV/TLC, FeNO and FEV1) were independently associated with positive methacholine challenge and the combination of these three variables yielded a specificity of 77%, a sensitivity of 39% and an AUC of 0.77. The RV/TLC ratio combined to FeNO may be of interest to predict significant methacholine bronchial hyperresponsiveness.
Topics: Adrenal Cortex Hormones; Adult; Aged; Anti-Asthmatic Agents; Asthma; Breath Tests; Bronchi; Female; Humans; Male; Methacholine Chloride; Middle Aged; Nitric Oxide; Plethysmography, Whole Body; Reproducibility of Results; Respiratory Function Tests
PubMed: 32305435
DOI: 10.1016/j.bcp.2020.113981 -
Journal of Applied Physiology... Jan 2021The obesity epidemic is causing a rise in asthma incidence due to the appearance of an obesity-specific late-onset nonallergic (LONA) phenotype. We investigated why only...
The obesity epidemic is causing a rise in asthma incidence due to the appearance of an obesity-specific late-onset nonallergic (LONA) phenotype. We investigated why only a subset of obese participants develop LONA asthma by determining how obesity, both alone and in combination with LONA asthma, affects the volume dependence of respiratory system impedance. We also determined how obesity and asthma affect impedance during and following challenge with the PC dose of methacholine. We found during passive exhalation that all obese participants, in contrast to lean controls and lean asthmatics, experienced similarly profound elevations in lung elastance as they approached functional residual capacity. We also found, however, that the LONA asthmatics had a greater negative dependence of airway resistance on lung volume over the middle of the volume range compared with the other groups. Methacholine challenge with the PC dose led to comparable changes in respiratory system impedance in the four study groups, but the doses themselves were substantially lower in both obese and lean asthmatic participants compared with obese and lean controls. Also, the obese LONA asthmatics had higher breathing frequencies and lower tidal volumes postchallenge compared with the other participants. Taken together, these results suggest that all obese individuals experience substantial lung collapse as they approach functional residual capacity, presumably due to the weight of the chest wall. It remains unclear why obese LONA asthmatics are hyperresponsive to methacholine while obese nonasthmatic individuals are not. Why only a subset of severely obese subjects develop late-onset nonallergic (LONA) asthma remains unknown, although it is widely assumed that compression of the lungs by the chest wall is somehow involved. We show that lung compression is common to obese individuals both without asthma and with LONA asthma but that those with LONA asthma may have increased airway wall compliance and possibly also a reduced ability to recruit collapsed lung.
Topics: Asthma; Bronchial Provocation Tests; Forced Expiratory Volume; Humans; Methacholine Chloride; Obesity
PubMed: 33119471
DOI: 10.1152/japplphysiol.00666.2020 -
Respiratory Care Dec 2021Methacholine bronchoprovocation or challenge testing (MCT) is commonly performed to assess airway hyper-responsiveness in the setting of suspected asthma. Nebulization...
BACKGROUND
Methacholine bronchoprovocation or challenge testing (MCT) is commonly performed to assess airway hyper-responsiveness in the setting of suspected asthma. Nebulization is an aerosol-generating procedure, but little is known about the risks of MCT in the context of the ongoing coronavirus disease 2019 (COVID-19) pandemic. We aimed to quantify and characterize aerosol generation during MCT by using different delivery methods and to assess the impact of adding a viral filter.
METHODS
Seven healthy subjects performed simulated MCT in a near particle-free laboratory space with 4 different nebulizers and with a dosimeter. Two devices continuously sampled the ambient air during the procedure, which detected ultrafine particles, from 0.02-1 μm, and particles of sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10 µm, respectively. Particle generation was compared among all the devices, with and without viral filter placement.
RESULTS
Ultrafine-particle generation during simulated MCT was significant across all the devices. Ultrafine-particle (0.02-1 μm) concentrations decreased 77%-91% with the addition of a viral filter and varied significantly between unfiltered < .001) and filtered devices < .001). Ultrafine-particle generation was lowest when using the dosimeter with filtered Hudson nebulizer (1,258 ± 1,644 particle/mL). Ultrafine-particle concentrations with the filtered nebulizer devices using a compressor were higher than particle concentrations detected when using the dosimeter: Monaghan (3,472 ± 1,794 particles/mL), PARI (4,403 ± 2,948), Hudson (6,320 ± 1,787) and AirLife (9,523 ± 5,098).
CONCLUSIONS
The high particle concentrations generated during MCT pose significant infection control concerns during the COVID-19 pandemic. Particle generation during MCT was significantly reduced by using breath-actuated delivery and a viral filter, which offers an effective mitigation strategy.
Topics: Aerosols; COVID-19; Humans; Infection Control; Methacholine Chloride; Nebulizers and Vaporizers; Pandemics; Particle Size; SARS-CoV-2
PubMed: 34789516
DOI: 10.4187/respcare.09236 -
Respiratory Physiology & Neurobiology Jan 2019To clarify the potential of dopamine to alter airway tone in the presence of different bronchoconstrictor stimuli, changes in airway function following dopamine...
To clarify the potential of dopamine to alter airway tone in the presence of different bronchoconstrictor stimuli, changes in airway function following dopamine administrations were characterized when the bronchial tone was elevated by stimulating the histaminic or cholinergic pathway. Airway resistance, tissue damping and tissue elastance were measured in anesthetized mechanically ventilated rabbits under baseline conditions, during steady-state bronchoconstriction induced by methacholine or histamine, and following intravenous dopamine (5 and 15 μg/kg/min). Bronchoconstriction induced by methacholine and histamine was significantly ameliorated by dopamine (14.8 ± 2.9% and 14.9 ± 2.9%; p < 0.05 for both), with no difference between the mode of stimuli. Dopamine had no effect on the tissue mechanics. These findings indicate that dopamine relaxes the elevated airway smooth muscle tone without affecting the lung periphery, and this effect is independent of the mode of constrictor stimuli. This profile of dopamine suggests its ability to treat effectively cholinergic and histaminergic bronchoconstriction, besides its positive inotropic effects on the myocardial contractility.
Topics: Airway Resistance; Animals; Blood Pressure; Bronchoconstriction; Dopamine; Heart Rate; Histamine; Methacholine Chloride; Muscarinic Agonists; Muscle, Smooth; Rabbits; Respiratory Mechanics
PubMed: 30367990
DOI: 10.1016/j.resp.2018.10.006 -
Respiratory Care Aug 2015A low serum vitamin D level may represent a marker of other perplexing factors that may lead to increased asthma prevalence and severity. Our aim was to assess the...
BACKGROUND
A low serum vitamin D level may represent a marker of other perplexing factors that may lead to increased asthma prevalence and severity. Our aim was to assess the correlation between vitamin D levels and asthma and allergy markers in a subgroup of children with fewer confounding factors.
METHODS
Non-obese children (6-18 y old) with asthma who were not receiving anti-inflammatory treatment were recruited. Subjects underwent spirometry with a methacholine challenge test, and fractional exhaled nitric oxide (FENO), serum vitamin D levels, total immunoglobulin E (IgE) levels, blood eosinophil counts, and high-sensitivity C-reactive protein levels were determined. The primary end point was the correlation between vitamin D level and airway hyper-responsiveness as assessed by a methacholine challenge test. The secondary end point was the correlation between vitamin D level and FENO, systemic inflammatory markers, and allergy.
RESULTS
Seventy-one children with asthma (25 females, 35%; 12.5 ± 3.6 y of age) were included. The median vitamin D level was 23 ng/mL (range of 6-48.5, mean of 23.02 ± 7.74), the median IgE level was 305 IU/mL (range of 4.3-4,240), the median provocational concentration of methacholine that produced a 20% decrease in FEV1 was 1.1 mg/mL (range of 0-13.9), and the median FENO was 26.5 ppb (range of 3.6-285). No correlation was found between vitamin D level and response to the methacholine challenge test, FENO, high-sensitivity C-reactive protein levels, IgE levels, eosinophil counts, and frequency of allergic rhinitis or atopic dermatitis.
CONCLUSIONS
In our group of children with asthma, no correlation was found between the level of vitamin D and the degree of airway reactivity, airway inflammation, and allergy. The cause-and-effect relationship between vitamin D, asthma, and allergy should be further clarified. (ClinicalTrials.gov registration NCT01287455).
Topics: Adolescent; Asthma; Biomarkers; Bronchial Provocation Tests; Bronchoconstrictor Agents; C-Reactive Protein; Child; Eosinophils; Female; Humans; Hypersensitivity; Immunoglobulin E; Inflammation Mediators; Leukocyte Count; Male; Methacholine Chloride; Nitric Oxide; Pulmonary Elimination; Spirometry; Vitamin D
PubMed: 25899478
DOI: 10.4187/respcare.03763 -
International Archives of Allergy and... 2015There is increasing interest in the role of indirect bronchial challenges because clinical studies have shown that indirect airway hyperresponsiveness (AHR) reflects...
BACKGROUND
There is increasing interest in the role of indirect bronchial challenges because clinical studies have shown that indirect airway hyperresponsiveness (AHR) reflects underlying airway inflammation better than direct AHR. Fractional exhaled nitric oxide (FeNO) appears to be a useful clinical tool for assessing airway inflammation noninvasively. We examined whether FeNO is more closely related to AHR to indirect stimuli than AHR to direct stimuli in children with mild to moderate asthma.
METHODS
Fifty-nine asthmatic children aged 6-16 years without rhinitis, underwent spirometry, FeNO measurement and blood tests for serum total IgE, blood eosinophil count and serum eosinophil cationic protein (ECP). All subjects underwent methacholine and adenosine 5-monophosphate (AMP) challenge tests at intervals of 3 days.
RESULTS
In a univariate linear regression analysis, FeNO was significantly associated with both PC20 AMP (R(2) = 0.341, p < 0.001) and PC20 methacholine (R(2) = 0.188, p = 0.001). After adjustment for age, sex, serum total IgE and blood eosinophil count, the association between FeNO and PC20 AMP (β = -1.98, p = 0.001) was more robust than that between FeNO and PC20 methacholine (β = -0.87, p = 0.081). The significant correlation between FeNO and PC20 AMP was observed in the steroid-naïve group (β = -2.48, p = 0.001), but not in the steroid-treated group (β = 0.88, p = 0.463).
CONCLUSIONS
FeNO levels were more closely associated with PC20 AMP than with PC20 methacholine. This relationship could only be seen in the steroid-naïve subjects. These results suggest that FeNO levels in children with asthma may be more closely related to indirect AHR than to direct AHR.
Topics: Adenosine Monophosphate; Adolescent; Asthma; Breath Tests; Bronchial Provocation Tests; Child; Eosinophil Cationic Protein; Eosinophils; Female; Humans; Immunoglobulin E; Inflammation; Linear Models; Male; Methacholine Chloride; Nitric Oxide
PubMed: 25792296
DOI: 10.1159/000375237 -
BMJ Open Respiratory Research May 2024Methods used to assess ventilation heterogeneity through inert gas washout have been standardised and showed high sensitivity in diagnosing many respiratory diseases. We... (Observational Study)
Observational Study Comparative Study
BACKGROUND
Methods used to assess ventilation heterogeneity through inert gas washout have been standardised and showed high sensitivity in diagnosing many respiratory diseases. We hypothesised that nitrogen single or multiple breath washout tests, respectively nitrogen single breath washout (NSBW) and nitrogen multiple breath washout (NMBW), may be pathological in patients with clinical suspicion of asthma but normal spirometry. Our aim was to assess whether NSBW and NMBW are associated with methacholine challenge test (MCT) results in this population. We also postulated that an alteration in S at NSBW could be detected before the 20% fall of forced expiratory volume in the first second (FEV) in MCT.
STUDY DESIGN AND METHODS
This prospective, observational, single-centre study included patients with suspicion of asthma with normal spirometry. Patients completed questionnaires on symptoms and health-related quality-of-life and underwent the following lung function tests: NSBW (S), NMBW (Lung clearance index (LCI), S, S), MCT (FEV and sGeff) as well as NSBW between each methacholine dose.
RESULTS
182 patients were screened and 106 were included in the study, with mean age of 41.8±14 years. The majority were never-smokers (58%) and women (61%). MCT was abnormal in 48% of participants, NSBW was pathological in 10.6% at baseline and NMBW abnormality ranged widely (LCI 81%, S 18%, S 43%). The dose response rate of the MCT showed weak to moderate correlation with the subsequent NSBW measurements during the provocation phases (ρ 0.34-0.50) but no correlation with NMBW.
CONCLUSIONS
Both MCT and N washout tests are frequently pathological in patients with suspicion of asthma with normal spirometry. The weak association and lack of concordance across the tests highlight that they reflect different but not interchangeable pathological pathways of the disease.
Topics: Humans; Asthma; Methacholine Chloride; Female; Male; Prospective Studies; Adult; Spirometry; Breath Tests; Middle Aged; Nitrogen; Bronchial Provocation Tests; Forced Expiratory Volume; Respiratory Function Tests; Lung; Bronchoconstrictor Agents
PubMed: 38697675
DOI: 10.1136/bmjresp-2023-001919 -
JVS-vascular Science 2023Arterial ring testing is the gold standard for measuring arterial function. Increased arterial tone through arterial contraction and impaired endothelial relaxation...
OBJECTIVE
Arterial ring testing is the gold standard for measuring arterial function. Increased arterial tone through arterial contraction and impaired endothelial relaxation (endothelial dysfunction) are key metrics of impaired arterial health in peripheral arterial disease (PAD). To allow for comparative testing of arteries during standard laboratory hours, storage buffers and conditions have been used to extend the functional life of arteries. Various storage conditions have been compared, but there has not been a robust comparison or validation in human arteries. The objective of this work is to optimize storage of arterial segments for endothelial cell (EC) testing in a murine model and to test EC function in human PAD arteries. We hypothesized that certain storage conditions would be superior to others.
METHODS
Healthy murine aortas were harvested from 10- to 14-week-old C57/Bl6J male and female mice and compared under different storage protocols (24 hours) to immediate arterial testing. The storage conditions tested were: Opti-MEM (37°C or 4°C), Krebs-HEPES with 1.8 mmol/L or 2.5 mmol/L calcium (4°C), or Wisconsin (WI) solution at 4°C. Vascular function was evaluated by isometric force testing. Endothelium-dependent and -independent relaxation were measured after precontraction with addition of methacholine or sodium nitroprusside, respectively. Arterial contraction was stimulated with potassium chloride or phenylephrine. Analysis of variance was used to determine significance compared with immediate testing with < .05. Under institutional review board approval, 28 PAD arteries were collected at amputation and underwent vascular function testing as described. Disturbed flow conditions were determined by indirect (upstream occlusion) flow to the harvested tibial arteries. Stable flow arteries had in-line flow. Arterial calcification was quantified manually as present or not present.
RESULTS
We found that 4°C WI and 37°C Opti-MEM best preserved endothelium-dependent relaxation and performed similarly to immediately testing aortas (termed fresh for freshly tested) ( > .95). Other storage conditions were inferior to freshly tested aortas ( < .05). Vascular smooth muscle function was tested by endothelial-independent relaxation and contractility. All storage conditions preserved endothelial-independent relaxation and contractility similar to freshly tested arteries. However, 4°C WI and 37°C Opti-MEM storage conditions most closely approximated the maximum force of contraction of freshly tested arteries in response to potassium chloride ( > .39). For human arterial testing, 28 tibial arteries were tested for relaxation and contraction with 16 arteries with peripheral artery occlusive disease (PAD with disturbed flow) and 12 without peripheral artery occlusive disease (PAD with stable flow), of which 14 were calcified and 14 were noncalcified. Endothelial-dependent relaxation data was measurable in 9 arteries and arterial contraction data was measurable in 14 arteries. When comparing flow conditions, arteries exposed to disturbed flow (n = 4) had significantly less relaxation (2% vs 59%; = .03) compared with stable flow conditions (n = 5). In contrast, presence the (n = 6) or absence of calcification (n = 3) did not impact arterial relaxation. Arterial contraction was not different between groups in either comparison by flow (n = 9 disturbed; n = 5 stable) or calcification (n = 6 present; n = 8 absent).
CONCLUSIONS
In healthy murine aortas, arterial storage for 24 hours in 4°C WI or 37°C Opti-MEM both preserved endothelium-dependent relaxation and maximum force of contraction. In human PAD arteries stored in 4° WI, flow conditions before arterial harvest, but not arterial calcification, led to differences in arterial relaxation in human PAD arteries. Arterial contractility was more robust (11/28 arteries) compared with arterial relaxation (7/28 arteries), but was not significantly different under flow or calcification parameters. This work defines ideal storage conditions for arterial ring testing and identifies that EC dysfunction from disturbed flow may persist in delayed ex vivo arterial testing.
PubMed: 37649473
DOI: 10.1016/j.jvssci.2023.100122