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American Journal of Physiology. Lung... Feb 2022There are renewed interests in using the parameter K of Salazar-Knowles' equation to assess lung tissue compliance. K either decreases or increases when the lung's...
There are renewed interests in using the parameter K of Salazar-Knowles' equation to assess lung tissue compliance. K either decreases or increases when the lung's parenchyma stiffens or loosens, respectively. However, whether K is affected by other common features of respiratory diseases, such as inflammation and airway smooth muscle (ASM) contraction, is unknown. Herein, male C57BL/6 mice were treated intranasally with either saline or lipopolysaccharide (LPS) at 1 mg/kg to induce pulmonary inflammation. They were then subjected to either a multiple or a single-dose challenge with methacholine to activate ASM to different degrees. A quasi-static pressure-driven partial pressure-volume (P-V) maneuver was performed before and after methacholine. The Salazar-Knowles' equation was then fitted to the deflation limb of the P-V loop to obtain K, as well as the parameter A, an estimate of lung volume (inspiratory capacity). The fitted curve was also used to derive the quasi-static elastance (E) at 5 cmHO. The results demonstrate that LPS and both methacholine challenges increased E. LPS also decreased A, but did not affect K. In contradistinction, methacholine decreased both A and K in the multiple-dose challenge, whereas it decreased K but not A in the single-dose challenge. These results suggest that LPS increases E by reducing the open lung volume (A) and without affecting tissue compliance (K), whereas methacholine increases E by decreasing tissue compliance with or without affecting lung volume. We conclude that lung tissue compliance, assessed using the parameter K of Salazar-Knowles' equation, is insensitive to inflammation but sensitive to ASM contraction.
Topics: Airway Resistance; Animals; Inflammation; Lipopolysaccharides; Lung; Lung Compliance; Male; Methacholine Chloride; Mice; Mice, Inbred C57BL; Muscle Contraction; Respiratory Mechanics
PubMed: 34936511
DOI: 10.1152/ajplung.00384.2021 -
Archivos de Bronconeumologia Feb 2023The role of bronchial provocation tests in the diagnosis of asthma remains to be fully explored. We aimed to evaluate methacholine and mannitol challenge testing, and... (Randomized Controlled Trial)
Randomized Controlled Trial Observational Study
INTRODUCTION
The role of bronchial provocation tests in the diagnosis of asthma remains to be fully explored. We aimed to evaluate methacholine and mannitol challenge testing, and explore the factors associated with this broncoprovocation response.
METHODS
Observational, cross-over, randomized trial evaluating adult cases with suspected asthma, naïve to treatment, with normal pre-bronchodilator spirometry, and negative bronchodilator test. Patients were randomized to start with methacholine or mannitol. The diagnosis of bronchial asthma was confirmed if there was a good functional and clinical response to one month with twice daily formoterol/budesonide 9/320. The diagnostic profile and the concordance were calculated. Factors associated with a positive provocation test were entered into a multivariate binomial logistic regression analysis, and classification trees were created for both tests.
RESULTS
The study included 108 cases (50.0% diagnosed with asthma and 51.9% cases starting with methacholine). The percentage of cases positive to methacholine and mannitol were 30.6% and 25.0% respectively. Kappa values were 0.40 (p<0.001). The diagnostic profile for methacholine was sensitivity 59.3% and specificity 98.1%, while for mannitol it was sensitivity 48.1% and specificity 98.1%. Variables associated with a positive methacholine response included sex, atopy, FEV, FEV/FVC and FENO, whereas they were FEV/FVC and FENO for mannitol. A FENO value>26ppb, FEV1≤103.3% and female sex correctly classified 78.7% of methacholine responders. FENO value>26ppb was enough to correctly classify 81.5% of mannitol responders.
CONCLUSIONS
Our study confirms the diagnostic profile of methacholine and mannitol challenge tests and describes the variable associated to their positivity with new proposed cutoff values.
Topics: Adult; Humans; Bronchial Provocation Tests; Methacholine Chloride; Bronchodilator Agents; Cross-Over Studies; Nitric Oxide; Asthma; Mannitol
PubMed: 36371327
DOI: 10.1016/j.arbres.2022.10.008 -
American Journal of Physiology. Lung... Apr 2021Obesity increases incidence and severity of asthma but the molecular mechanisms are not completely understood. Hyperinsulinemia potentiates vagally induced...
Obesity increases incidence and severity of asthma but the molecular mechanisms are not completely understood. Hyperinsulinemia potentiates vagally induced bronchoconstriction in obese rats. Since bronchoconstriction results from airway smooth muscle contraction, we tested whether insulin changed agonist-induced airway smooth muscle contraction. Obesity-prone and resistant rats were fed a low-fat diet for 5 wk and treated with insulin (Lantus, 3 units/rat sc) 16 h before vagally induced bronchoconstriction was measured. Ex vivo, contractile responses to methacholine were measured in isolated rat tracheal rings and human airway smooth muscle strips before and after incubation (0.5-2 h) with 100 nM insulin or 13.1 nM insulin like growth factor-1 (IGF-1). M and M muscarinic receptor mRNA expression was quantified by qRT-PCR and changes in intracellular calcium were measured in response to methacholine or serotonin in isolated rat tracheal smooth muscle cells treated with 1 µM insulin. Insulin, administered to animals 16 h prior, potentiated vagally induced bronchoconstriction in both obese-prone and resistant rats. Insulin, not IGF-1, significantly increased methacholine-induced contraction of rat and human isolated airway smooth muscle. In cultured rat tracheal smooth muscle cells, insulin significantly increased M, not M mRNA expression and enhanced methacholine- and serotonin-induced increase in intracellular calcium. Insulin alone did not cause an immediate increase in intracellular calcium. Thus, insulin acutely potentiated agonist-induced increase in intracellular calcium and airway smooth muscle contraction. These findings may explain why obese individuals with hyperinsulinemia are prone to airway hyperreactivity and give insights into future targets for asthma treatment.
Topics: Animals; Bronchial Hyperreactivity; Bronchoconstriction; Calcium; Humans; Hyperinsulinism; Hypoglycemic Agents; Insulin; Male; Methacholine Chloride; Muscarinic Agonists; Muscle Contraction; Muscle, Smooth; Obesity; Rats; Rats, Sprague-Dawley; Receptors, Muscarinic; Trachea; Vagus Nerve
PubMed: 33501891
DOI: 10.1152/ajplung.00232.2020 -
Drug Design, Development and Therapy 2020Hesperetin-5,7,3'--trimethylether (HTME), a synthetic liposoluble hesperetin, has been reported to be a dual phosphodiesterase (PDE)3/4 inhibitor. We investigated its...
INTRODUCTION
Hesperetin-5,7,3'--trimethylether (HTME), a synthetic liposoluble hesperetin, has been reported to be a dual phosphodiesterase (PDE)3/4 inhibitor. We investigated its inhibitory effects on methacholine (MCh)-induced airway hyperresponsiveness (AHR) and its potential for treating atypical asthma and COPD.
METHODS
FlexiVent system was used to determine AHR in ovalbumin (OVA) sensitized and challenged mice. Determination of cytokines was performed by using mouse T helper (Th)1/Th2 cytokine CBA kits, and of total immunoglobulin (Ig)E and OVA-specific IgE using ELISA kits. The number of inflammatory cells was counted using a hemocytometer. Xylazine/ketamine-induced anesthesia was to assess nausea, vomiting, and gastric hypersecretion in these mice.
RESULTS
HTME dually and competitively inhibited PDE3/4 activities in the Lineweaver-Burk analysis. HTME (30 and 100 μmol/kg) dose-dependently and significantly decreased the airway resistance (R) and increased lung dynamic compliance (C) values induced by MCh. It significantly suppressed numbers of total inflammatory cells and neutrophils, and levels of cytokines in bronchoalveolar lavage fluid (BALF). HTME dose-dependently and significantly inhibited total and OVA-specific IgE levels in the BALF and serum. However, HTME did not influence xylazine/ketamine-induced anesthesia.
CONCLUSION
HTME exerted anti-inflammatory and bronchodilator effects and may be useful in treating chronic obstructive pulmonary disease and allergic atypical asthma with no gastrointestinal side effects.
Topics: Animals; Anti-Inflammatory Agents; Dose-Response Relationship, Drug; Female; Hesperidin; Methacholine Chloride; Mice; Mice, Inbred BALB C; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Respiratory Hypersensitivity
PubMed: 32099334
DOI: 10.2147/DDDT.S227432 -
International Journal of Occupational... Mar 2020Various indirect or direct airway challenge tests are used to measure nonspecific bronchial hyper-responsiveness (NSBHR). The evaluation of NSBHR in diagnosing...
OBJECTIVES
Various indirect or direct airway challenge tests are used to measure nonspecific bronchial hyper-responsiveness (NSBHR). The evaluation of NSBHR in diagnosing occupational asthma (OA) is performed, e.g., to monitor the specific inhalation challenge test (SICT). The aim of this study was to preliminarily compare the results of methacholine and mannitol inhalation challenge tests in SICT monitoring in bakers with work-related airway symptoms.
MATERIAL AND METHODS
Four bakery workers with a suspicion of OA underwent single-blind placebo-controlled SICTs involving workplace allergens, accompanied by the evaluation of NSBHR with mannitol and methacholine, both before and after SICTs. Clinical examinations, spirometry tests, skin prick tests (SPTs) to common aeroallergens and occupational allergens, as well as tests to determine serum specific IgE antibodies to occupational aeroallergens were also performed.
RESULTS
Positive SPTs results to occupational aeroallergens were found in all bakery workers, and specific IgE antibodies to flour were detected in 2 subjects. Three patients displayed positive SICT reactions. In all of these 3 patients, airway responsiveness to methacholine increased significantly. In 2 patients, airway reaction to mannitol was significant, whereas in 1 subject there was no increase in NSBHR after mannitol inhalation. The patient with a negative SICT result did not reveal any changes in NSBHR before and after the test, either to methacholine or mannitol.
CONCLUSIONS
The data obtained by the authors show that there is no clear correlation between the methacholine and mannitol inhalation challenge tests in SICT monitoring. Preliminary results indicate the need for further investigations to evaluate the usefulness of the mannitol challenge test in the diagnostics of OA. Int J Occup Med Environ Health. 2020;33(2):235-9.
Topics: Adult; Allergens; Asthma, Occupational; Bronchial Provocation Tests; Female; Humans; Male; Mannitol; Methacholine Chloride; Middle Aged; Single-Blind Method
PubMed: 32080681
DOI: 10.13075/ijomeh.1896.01459 -
International Archives of Allergy and... 2020Bronchoconstriction was recently shown to cause airway remodeling and induce allergic airway inflammation in asthma. However, the mechanisms how mechanical stress via...
INTRODUCTION
Bronchoconstriction was recently shown to cause airway remodeling and induce allergic airway inflammation in asthma. However, the mechanisms how mechanical stress via bronchoconstriction could induce airway inflammation and remodeling remain unclear.
OBJECTIVE
We investigated the effect of bronchoconstriction induced by methacholine inhalation in a murine model of asthma.
METHODS
BALB/c female mice were sensitized and challenged with ovalbumin (OVA), followed by treatment with methacholine by a nebulizer twice a day for 7 days. Twenty-four hours after the last methacholine treatment, the bronchoalveolar lavage fluid (BALF) and lung tissues were collected. The BALF was analyzed for total and differential cell counts and cytokine levels. The lung tissues were analyzed for goblet cell metaplasia, thickness of the smooth muscle, and lung fibrosis. The expression of cytokines in the lung was also examined.
RESULTS
OVA sensitization and challenge induced infiltration of total cells, macrophages, and eosinophils in the BALF along with goblet cell metaplasia and increased airway smooth muscle hypertrophy. Seven days after the last OVA challenge, untreated mice achieved reduction in airway inflammation, while methacholine maintained the number of BALF total cells, macrophages, and eosinophils. The percentage of goblet cells and the thickness of airway smooth muscle were also maintained by methacholine. Moreover, the treatment of methacholine induced the expression of transforming growth factor (TGF)-β in the lung. This result indicates that the production of TGF-β is involved in induction of airway remodeling caused by bronchoconstriction with methacholine.
CONCLUSIONS
Repeated bronchoconstriction caused by methacholine inhalation elicited allergic airway inflammation and airway remodeling.
Topics: Administration, Inhalation; Allergens; Animals; Asthma; Bronchoconstriction; Disease Models, Animal; Eosinophils; Female; Humans; Lung; Macrophages; Methacholine Chloride; Mice; Mice, Inbred BALB C; Ovalbumin; Transforming Growth Factor beta
PubMed: 32791506
DOI: 10.1159/000509606 -
Occupational Medicine (Oxford, England) Feb 2022Firefighter applicants (FFAs) with a history of asthma may be refused entry to the fire service because of potentially putting themselves and others at risk.
BACKGROUND
Firefighter applicants (FFAs) with a history of asthma may be refused entry to the fire service because of potentially putting themselves and others at risk.
AIMS
We undertook a service evaluation to identify respiratory and employment outcomes of FFAs with a history of asthma who had undergone additional respiratory assessment at our specialist occupational lung disease clinic during 2005-19.
METHODS
We reviewed FFA medical records and categorized them as having either no current asthma or definite/probable asthma at the time of clinic assessment. 'No current asthma' was defined as negative non-specific bronchial hyper-responsiveness (BHR) to histamine/methacholine, and no symptoms or treatment within the 2 years before clinic. 'Definite/probable current asthma' was defined as either positive BHR, or negative BHR with symptoms and/or treatment within the previous 2 years. Around 1 year later, we contacted FFAs to enquire about their application outcome and current respiratory symptoms.
RESULTS
Data were available on 116 applicants; of whom, 45% (n = 52) had definite/probable current asthma and were significantly more likely to be older, atopic to common aeroallergens, report atopic disease and have a lower forced expiratory volume in one second/forced vital capacity ratio compared with applicants with no current asthma. Only two individuals' applications were rejected due to asthma. At follow-up, just 2 (2%) of the 90 operational firefighters reported any recent trouble with asthma.
CONCLUSIONS
A history of asthma alone is not sufficient to determine current asthma in FFAs. Even with a diagnosis of current asthma, FFAs are mostly successful in their application to join the fire service.
Topics: Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Firefighters; Forced Expiratory Volume; Humans; Methacholine Chloride
PubMed: 34919722
DOI: 10.1093/occmed/kqab162 -
American Journal of Respiratory Cell... Mar 2021Vitamin D (VitD) has pleiotropic effects. VitD deficiency is closely involved with obesity and may contribute to the development of lung fibrosis and aggravation of...
Vitamin D (VitD) has pleiotropic effects. VitD deficiency is closely involved with obesity and may contribute to the development of lung fibrosis and aggravation of airway hyperresponsiveness (AHR). We evaluated the causal relationship between VitD deficiency and the lung pathologies associated with obesity. effects of VitD supplementation were analyzed using high-fat diet (HFD)-induced obese mice and TGF-β1 (transforming growth factor-β1) triple transgenic mice. Effects of VitD supplementation were also evaluated in both BEAS-2B and primary lung cells from the transgenic mice. Obese mice had decreased 25-OH VitD and VitD receptor expressions with increases of insulin resistance, renin and angiotensin-2 system (RAS) activity, and leptin. In addition, lung pathologies such as a modest increase in macrophages, enhanced TGF-β1, IL-1β, and IL-6 expression, lung fibrosis, and AHR were found. VitD supplementation to HFD-induced obese mice recovered these findings. TGF-β1-overexpressing transgenic mice enhanced macrophages in BAL fluid, lung expression of RAS, epithelial-mesenchymal transition markers, AHR, and lung fibrosis. VitD supplementation also attenuated these findings in addition to the attenuation of the expressions of TGF-β1, and phosphorylated Smad-2/3 in lung. Supplementing -stimulated BEAS-2B and primary lung cells with VitD inhibited TGF-β1 expression, supporting the suppressive effect of VitD for TGF-β1 expression. These results suggest that obesity leads to VitD deficiency and worsens insulin resistance while enhancing the expression of leptin, RAS, TGF-β1, and proinflammatory cytokines. These changes may contribute to the development of lung fibrosis and AHR. VitD supplementation rescues these changes and may have therapeutic potential for asthma with obesity.
Topics: Animals; Biomarkers; Body Weight; Cells, Cultured; Cytokines; Diet, High-Fat; Dietary Supplements; Epithelial-Mesenchymal Transition; Glucose Tolerance Test; Inflammation; Insulin; Leptin; Lung; Male; Methacholine Chloride; Mice, Inbred C57BL; Mice, Transgenic; Obesity; Pulmonary Fibrosis; Receptors, Calcitriol; Renin; Renin-Angiotensin System; Respiratory Hypersensitivity; Transforming Growth Factor beta1; Vitamin D; Vitamin D Deficiency; Mice
PubMed: 33296297
DOI: 10.1165/rcmb.2020-0086OC -
Automated, high temporal resolution mechanics measurements during incubation of contractile tissues.Journal of Biomechanics May 2023Muscle tissue mechanics and contractility measurements have a great advantage over cultured cell level experiments as their mechanical and contractile properties are...
Muscle tissue mechanics and contractility measurements have a great advantage over cultured cell level experiments as their mechanical and contractile properties are much closer to in vivo tissue properties. However, tissue level experiments cannot be combined with incubation with the same time resolution and consistency as cell culture studies. Here we present a system in which contractile tissues can be incubated for days while intermittently being tested for their mechanical and contractile properties. A two-chamber system was developed with control of temperature in the outer chamber and CO and humidity control in the inner, sterile chamber. Incubation medium, to which biologically active components may be added, is reused after each mechanics test to preserve both added and released components. Mechanics and contractility are measured in a different medium to which, through a high accuracy syringe pump, up to 6 different agonists in a 100-fold dose range can be added. The whole system can be operated through fully automated protocols from a personal computer. Testing data shows accurate maintenance of temperature, CO and relative humidity at pre-set levels. Equine trachealis smooth muscle tissues tested in the system showed no signs of infection after 72 h with incubation medium replacement every 24 h. Methacholine dosing and electrical field stimulation every 4 h showed consistent responses. In conclusion, the developed system is a great improvement on the manual incubation techniques being used thus far, improving on time resolution, repeatability and robustness, while reducing contamination risk and tissue damage from repeated handling.
Topics: Animals; Horses; Carbon Dioxide; Muscle, Smooth; Muscle Contraction; Methacholine Chloride; Cells, Cultured
PubMed: 37058766
DOI: 10.1016/j.jbiomech.2023.111577 -
American Journal of Physiology. Lung... Oct 2022The enzyme, nitric oxide-sensitive guanylyl cyclase (NO-GC), is activated by binding NO to its prosthetic heme group and catalyzes the formation of cGMP. The NO-GC is...
The enzyme, nitric oxide-sensitive guanylyl cyclase (NO-GC), is activated by binding NO to its prosthetic heme group and catalyzes the formation of cGMP. The NO-GC is primarily known to mediate vascular smooth muscle relaxation in the lung, and inhaled NO has been successfully used as a selective pulmonary vasodilator. In comparison, NO-GC's impact on the regulation of airway tone is less acknowledged and, most importantly, little is known about the issue that NO-GC signaling is accomplished by two isoforms: NO-GC1 and NO-GC2, implying the existence of distinct "cGMP pools." Herein, we investigated the functional role of the NO-GC isoforms in respiration by measuring lung function parameters of isoform-specific knockout (KO) mice using noninvasive and invasive techniques. Our data revealed the participation and ongoing influence of NO-GC1-derived cGMP in the regulation of airway tone by showing that respiratory resistance was enhanced in NO-GC1-KOs and increased more pronouncedly after the challenge with the bronchoconstrictor methacholine. The tissue resistance and stiffness of NO-GC1-KOs were also higher because of narrowed airways that cause tissue distortion. Contrariwise, NO-GC2-KOs displayed reduced tissue elasticity, elastic recoil, and airway reactivity to methacholine, which did not even increase in an ovalbumin model of asthma that induced hyperresponsiveness in NO-GC1-KOs. In addition, conscious NO-GC2-KOs showed a higher breathing rate with a shorter duration of inspiration and expiration time, which remained faster even in the presence of bronchoconstrictors that slow down breathing. Thus, we provide evidence of two distinct NO/cGMP pathways in airways, accomplished by either NO-GC1 or NO-GC2, adjusting differentially the airway reactivity.
Topics: Animals; Bronchoconstrictor Agents; Cyclic GMP; Guanylate Cyclase; Heme; Methacholine Chloride; Mice; Mice, Knockout; Nitric Oxide; Ovalbumin; Protein Isoforms; Soluble Guanylyl Cyclase; Vasodilator Agents
PubMed: 35972838
DOI: 10.1152/ajplung.00404.2021