Severe Airway Hyperresponsiveness Research Articles

Small airway function in predicting asthma control in preschool children

AbstractAsthma control in children is often challenging. This retrospective cohort study aimed to investigate the potential contribution of small airway function in predicting asthma control within a 2‐ to 3‐month period following the initial diagnosis in preschool children with asthma. A total of 219 preschool children diagnosed with asthma were enrolled, and their follow‐up was conducted by pediatric pulmonary physicians. Clinical history and lung function results were collected for analysis. To identify risk factors associated with poor asthma control, a multivariable regression model was employed. Sixty‐nine of the patients (31.5%) exhibited poor asthma control. Poor adherence to therapy (14.5% vs. 6.0%, p = 0.038) and the presence of severe airway hyperresponsiveness (AHR) (20.6% vs. 1.6%, p < 0.001) were more prevalent in the group with poor control. Additionally, baseline forced expiratory volume in 1 s in predicting (94.5% vs. 101.4%, p = 0.001), forced expiratory flows (FEF)50% (66.1% vs. 86.0%, p < 0.001), FEF75% (60.9% vs. 75.3%, p = 0.001), and FEF25–75% (70.9% vs. 86.0%, p < 0.001) were significantly lower in the poorly‐controlled group than those of well‐controlled group. There was no significant difference in forced vital capacity in predicting (FVC%) between the two groups (92.4% vs. 96.7%, p = 0.093). Multivariable regression model unveiled initial severe AHR (OR 8.595, 95%CI 1.241–59.537, p = 0.021) and decreased FEF50% (OR 0.971, 95%CI 0.949–0.994, p = 0.012) were significantly associated with short‐term poor asthma control. Preschool children with asthma who exhibites initial severe AHR and/or decreased FEF50% faces an elevated risk of encountering poor asthma control during the subsequent 2–3 months.

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Obesity-associated Airway Hyperresponsiveness: Mechanisms Underlying Inflammatory Markers and Possible Pharmacological Interventions

Abstract: Obesity is rapidly becoming a global health problem affecting about 13% of the world’s population affecting women and children the most. Recent studies have stated that obese asthmatic subjects suffer from an increased risk of asthma, encounter severe symptoms, respond poorly to anti-asthmatic drugs, and ultimately their quality-of-life decreases. Although, the association between airway hyperresponsiveness (AHR) and obesity is a growing concern among the public due to lifestyle and environmental etiologies, however, the precise mechanism underlying this association is yet to establish. Apart from aiming at the conventional antiasthmatic targets, treatment should be directed towards ameliorating obesity pathogenesis too. Understanding the pathogenesis underlying the association between obesity and AHR is limited, however, a plethora of obesity pathologies have been reported viz., increased pro-inflammatory and decreased anti-inflammatory adipokines, depletion of ROS controller Nrf2/HO-1 axis, NLRP3 associated macrophage polarization, hypertrophy of WAT, and down-regulation of UCP1 in BAT following down-regulated AMPKα and melanocortin pathway that may be correlated with AHR. Increased waist circumference (WC) or central obesity was thought to be related to severe AHR, however, some recent reports suggest body mass index (BMI), not WC tends to exaggerate airway closure in AHR due to some unknown mechanisms. This review aims to co-relate the above-mentioned mechanisms that may explain the copious relation underlying obesity and AHR with the help of published reports. A proper understanding of these mechanisms discussed in this review will ensure an appropriate treatment plan for patients through advanced pharmacological interventions.

Small airway dysfunction and impulse oscillometry in adult patients with asthma: recent findings

Asthma is a respiratory disease affecting more than 300 million people around the world. Airflow obstruction and inflammation due to asthma usually involve large airways, but recently small airway involvement (internal diameter < 2 mm) has been shown to represent one of the main determinants of asthma and asthma control. In fact, compared to large airway involvement, small airway dysfunction (SAD) has been demonstrated across all the asthma severity in the majority of patients, as assessed with Global Initiative for Asthma (GINA) steps. Clinically, SAD is associated with, among other features, exercise-induced bronchoconstriction, asthma-related night awakenings, obesity/overweight, more severe airway hyperresponsiveness, worse asthma control, and more severe exacerbations. Impulse oscillometry (IOS), a forced oscillation technique (FOT) requiring less effort than spirometry from the patients, demonstrated to accurately measure SAD in children and adults. The fall in resistance from 5 Hz to 20 Hz (R5–R20), which is the most used index for the resistance of peripheral airways, is how SAD is usually identified by IOS. Other crucial parameters measured by IOS are the reactance at 5 Hz (X5), reflecting elastic recoil of the peripheral airways, the resonant frequency (Fres), which is the frequency at which the inertial properties of the airway and the capacitance of the lung periphery are equal, and the reactance area (AX), reflecting the elastic properties of the lung periphery. In this mini review, the latest findings on the utility of IOS to identify SAD and the associations between SAD and clinical features in adult asthmatic patients were addressed.

The role of small airway function parameters in preschool asthmatic children

BackgroundSmall airways are the major sites of inflammation and airway remodeling in all severities of asthma patients. However, whether small airway function parameters could reflect the airway dysfunction feature in preschool asthmatic children remain unclear. We aim to investigate the role of small airway function parameters in evaluating airway dysfunction, airflow limitation and airway hyperresponsiveness (AHR).MethodsEight hundred and fifty-one preschool children diagnosed with asthma were enrolled retrospectively to investigate the characteristics of small airway function parameters. Curve estimation analysis was applied to clarify the correlation between small and large airway dysfunction. Spearman’s correlation and receiver-operating characteristic (ROC) curves were employed to evaluate the relationship between small airway dysfunction (SAD) and AHR.ResultsThe prevalence of SAD was 19.5% (166 of 851) in this cross-sectional cohort study. Small airway function parameters (FEF25-75%, FEF50%, FEF75%) showed strong correlations with FEV1% (r = 0.670, 0.658, 0.609, p<0.001, respectively), FEV1/FVC% (r = 0.812, 0.751, 0.871, p<0.001, respectively) and PEF% (r = 0.626, 0.635, 0.530, p<0.01, respectively). Moreover, small airway function parameters and large airway function parameters (FEV1%, FEV1/FVC%, PEF%) were curve-associated rather than linear-related (p<0.001). FEF25-75%, FEF50%, FEF75% and FEV1% demonstrated a positive correlation with PC20 (r = 0.282, 0.291, 0.251, 0.224, p<0.001, respectively). Interestingly, FEF25-75% and FEF50% exhibited a higher correlation coefficient with PC20 than FEV1% (0.282 vs. 0.224, p = 0.031 and 0.291 vs. 0.224, p = 0.014, respectively). ROC curve analysis for predicting moderate to severe AHR showed that the area under the curve (AUC) was 0.796, 0.783, 0.738, and 0.802 for FEF25-75%, FEF50%, FEF75%, and the combination of FEF25-75% and FEF75%, respectively. When Compared to children with normal lung function, patients with SAD were slightly older, more likely to have a family history of asthma and airflow obstruction with lower FEV1% and FEV1/FVC%, lower PEF% and more severe AHR with lower PC20 ( all p<0.05).ConclusionSmall airway dysfunction is highly correlated with large airway function impairment, severe airflow obstruction and AHR in preschool asthmatic children. Small airway function parameters should be utilized in the management of preschool asthma.

Comparison of positive and negative pressure extubation after mechanical ventilation in intensive care unit patients

To investigate the effect of positive and negative pressure extubation on mechanical ventilation patients in the intensive care unit (ICU). A prospective randomized controlled study was performed, 105 ICU patients who successfully passed the spontaneous breathing test (SBT) after mechanical ventilation of Nanjing Jiangbei Hospital Affiliated to Nantong University from January 2019 to March 2021 were enrolled. According to random number table method, they were randomly divided into positive pressure extubation group (53 cases) and negative pressure extubation group (52 cases). During extubation, all patients were placed in semi-decubitus position (raising the head of bed at an angle range from 30 degree angle- 45 degree angle), the secretions from mouth, nose, throat and trachea were removed. In the negative pressure extubation group, the sputum suction tube was inserted into the tracheal tube and passed over the distal opening to carry out continuous negative pressure suction in the tracheal tube after disconnecting the ventilator. Meanwhile, after the tracheal tube balloon was evacuated, the sputum suction tube was pulled out together with the tracheal tube. In the positive pressure extubation group, the patients were guided to inspiratory forcibly under the original SBT mode. When the patients reached the inspiratory peak, the ballon was evacuated and the tracheal tube was removed. After extubation, all patients were given nasal catheter oxygen inhalation (oxygen flow 5 L/min). Arterial blood gas analysis indexes [pH value, arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2)] were recorded 5 minutes and 1 hour after extubation in both groups. Vital signs (including tachypnea, tachycardia, elevated blood pressure and decreased oxygen saturation) and complications (including severe cough, airway hyperresponsiveness and pneumonia) were observed 30 minutes after extubation in both groups. Five minutes after extubation, blood gas analysis showed that the PaO2 of positive pressure extubation group was significantly higher than that of negative pressure extubation group [mmHg (1 mmHg ≈ 0.133 kPa): 123.4±30.2 vs. 111.0±21.1, P < 0.05], the pH value and PaCO2 in positive pressure extubation group were slightly lower than that of negative pressure extubation group [pH value: 7.411±0.042 vs. 7.419±0.040, PaCO2 (mmHg): 39.7±4.7 vs. 40.5±5.6], but the differences were not statistically significant (both P > 0.05). One hour after extubation, the pH value, PaO2 and PaCO2 in positive pressure extubation group were slightly lower than those in negative pressure extubation group, but the differences were not statistically significant. Within 30 minutes after extubation, the incedences of tachypnea, tachycardia, elevated blood pressure and oxygen desaturationin in positive pressure extubation group were significantly lower than those in negative pressure extubation group [tachypnea: 9.4% (5/53) vs. 28.8% (15/52), tachycardia: 15.1% (8/53) vs. 32.7% (17/52), elevated blood pressure: 11.3% (6/53) vs. 30.8% (16/52), oxygen desaturation: 7.5% (4/53) vs. 34.6% (18/52), all P < 0.05], the incidence of severe cough in positive pressure extubation group was significantly lower than that in negative pressure extubation group [9.4% (5/53) vs. 30.8% (16/52), P < 0.05], but there was no significant difference in the incidence of complications of airway hyperresponsiveness between the two groups [1.9% (1/53) vs. 5.8% (3/52), P > 0.05]. No pneumonia occurred in both groups within 48 hours after extubation. The positive pressure extubation method can ensure full oxygenation of patients undergoing mechanical ventilation in ICU, avoid hypoxia, and reduce the occurrence of hypoxia and severe cough, which is more conducive to the stability of vital signs.

Small-Airway Dysfunction is Involved in the Pathogenesis of Asthma: Evidence from Two Mouse Models.

BackgroundThere has been growing evidence of small-airway dysfunction in patients with asthma. Few studies have evaluated the mechanism of small-airway dysfunction in mouse models of asthma.PurposeWe explored the correlation between small-airway spirometric variables and large-airway function or inflammation in different endotypes of asthma.MethodsOvalbumin (OVA) sensitization/challenge was used to produce a type 2 (T2)-high asthma model, and OVA combined with ozone exposure (OVA + ozone) was used for the T2-low asthma model with increased neutrophils. Spirometry, airway responsiveness, cytokine levels in bronchoalveolar lavage fluid (BALF), and pathological analyses of lung slices stained with hematoxylin-eosin, periodic acid–Schiff, and Masson’s trichrome stain were all determined. Muc5ac expression in lung tissue was evaluated by the reverse transcription-polymerase chain reaction (RT-PCR), and alpha-smooth muscle actin was measured by immunohistochemistry.ResultsInflammatory cells infiltrated the lung tissue and inflammatory cytokines were increased in the BALF of both the OVA and OVA + ozone groups, compared with the control group. Peribronchial hypersecretion and collagen deposition were evident in the models. The OVA + ozone group showed greater neutrophilic infiltration and peribronchial smooth muscle proliferation than the OVA group. Large-airway obstruction, small-airway dysfunction, and airway hyperresponsiveness were confirmed in both models. Small-airway functional variables, such as MMEF (mean midexpiratory flow, average flow from 25 to 75% forced vital capacity [FVC]) and FEF50 (forced expiratory flow at 50% of FVC), were positively correlated with large-airway function and had a stronger negative correlation with airway inflammation, mucus secretion, and responsiveness than large-airway function.ConclusionSmall-airway dysfunction was evident in the two endotypes of asthma and was correlated with severe airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The small airways may be an important target in asthma treatment, and further research in the role of small-airway variables in the pathogenesis of asthma is warranted.

IL-4 and IL-17 Are Required for House Dust Mite-Driven Airway Hyperresponsiveness in Autoimmune Diabetes-Prone Non-Obese Diabetic Mice.

Allergic asthma is characterized by airway inflammation with a Th2-type cytokine profile, hyper-IgE production, mucus hypersecretion, and airway hyperreactivity (AHR). It is increasingly recognized that asthma is a heterogeneous disease implicating complex immune mechanisms resulting in distinct endotypes observed in patients. In this study, we showed that non-obese diabetic (NOD) mice, which spontaneously develop autoimmune diabetes, undergo more severe allergic asthma airway inflammation and AHR than pro-Th2 BALB/c mice upon house dust mite (HDM) sensitization and challenge. The use of IL-4-deficient NOD mice and the in vivo neutralization of IL-17 demonstrated that both IL-4 and IL-17 are responsible by the exacerbated airway inflammation and AHR observed in NOD mice. Overall, our findings indicate that autoimmune diabetes-prone NOD mice might become useful as a new HDM-induced asthma model to elucidate allergic dysimmune mechanisms involving Th2 and Th17 responses that could better mimic some asthmatic endoytpes.

RAGE and TLR4 differentially regulate airway hyperresponsiveness: Implications for COPD.

The receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4) is implicated in COPD. Although these receptors share common ligands and signalling pathways, it is not known whether they act in concert to drive pathological processes in COPD. We examined the impact of RAGE and/or TLR4 gene deficiency in a mouse model of COPD and also determined whether expression of these receptors correlates with airway neutrophilia and airway hyperresponsiveness (AHR) in COPD patients. We measured airway inflammation and AHR in wild-type, RAGE-/- , TLR4-/- and TLR4-/- RAGE-/- mice following acute exposure to cigarette smoke (CS). We also examined the impact of smoking status on AGER (encodes RAGE) and TLR4 bronchial gene expression in patients with and without COPD. Finally, we determined whether expression of these receptors correlates with airway neutrophilia and AHR in COPD patients. RAGE-/- mice were protected against CS-induced neutrophilia and AHR. In contrast, TLR4-/- mice were not protected against CS-induced neutrophilia and had more severe CS-induced AHR. TLR4-/- RAGE-/- mice were not protected against CS-induced neutrophilia but were partially protected against CS-induced mediator release and AHR. Current smoking was associated with significantly lower AGER and TLR4 expression irrespective of COPD status, possibly reflecting negative feedback regulation. However, consistent with preclinical findings, AGER expression correlated with higher sputum neutrophil counts and more severe AHR in COPD patients. TLR4 expression did not correlate with neutrophilic inflammation or AHR. Inhibition of RAGE but not TLR4 signalling may protect against airway neutrophilia and AHR in COPD.

IL-5 Exposure In Utero Increases Lung Nerve Density and Airway Reactivity in Adult Offspring.

Asthma is characterized by airway hyperreactivity and inflammation. In the lungs, parasympathetic and sensory nerves control airway tone and induce bronchoconstriction. Dysregulation of these nerves results in airway hyperreactivity. Humans with eosinophilic asthma have significantly increased sensory nerve density in airway epithelium, suggesting that type 2 cytokines and inflammatory cells promote nerve growth. Similarly, mice with congenital airway eosinophilia also have airway hyperreactivity and increased airway sensory nerve density. Here, we tested whether this occurs during development. We show that transgenic mice that overexpress IL-5, a cytokine required for eosinophil hematopoiesis, give birth to wild-type offspring that have significantly increased airway epithelial nerve density and airway hyperreactivity that persists into adulthood. These effects are caused by in utero exposure to maternal IL-5 and resulting fetal eosinophilia. Allergen exposure of these adult wild-type offspring results in severe airway hyperreactivity, leading to fatal reflex bronchoconstriction. Our results demonstrate that fetal exposure to IL-5 is a developmental origin of airway hyperreactivity, mediated by hyperinnervation of airway epithelium.

The correlation of adenosine challenge test results with subsequent clinical course among young children with suspected asthma: a retrospective cohort study

Our aim was to evaluate the correlation of Adenosine monophosphate challenge test (AMP-PCW) results with the patients' subsequent clinical course. We performed a 6-year retrospective cohort study of young children with suspected asthma who underwent AMP-PCW test. Fifty four children were included in the study (median age, 50.5 months; range, 26-90). AMP-PCW was positive in 35 (65%) children. During the 3-year follow-up period, among 22 of 35 patients in the positive AMP-PCW group and among 17 of 19 in the negative AMP-PCW group-prophylactic therapy was not changed. Prophylactic therapy was initiated or its dose was escalated in 12 of 13 (92.3%) of the children with a positive AMP-PCW test compared to none of the children with a negative challenge test (P < 0.001). Prophylactic therapy was discontinued in only one (7.6%) of the children with a positive test as compared to two (100%) of the children with a negative test (P < 0.001). There were significantly fewer severe asthma exacerbations during a 3-year follow-up period after the challenge test as compared to the preceding 3-year period both in children with a positive (from 34 to 9 total events, P = 0.01) or a negative challenge test (from 16 to 0 events P = 0.01). The severity of airway hyper responsiveness was found to associate with the number of severe asthma exacerbations (P = 0.04) and with a diagnosis of asthma during the following 3 years (P = 0.02). AMP-PCW test results correlates with the subsequent clinical course of young children with suspected asthma performing the test.

Cystathionine γ-lyase deficiency enhances airway reactivity and viral-induced disease in mice exposed to side-stream tobacco smoke.

BACKGROUND:Environmental tobacco smoke (ETS) is a known risk factor for severe respiratory syncytial virus (RSV) infections, yet the mechanisms of ETS/RSV co-morbidity are largely unknown. Cystathionine γ-lyase regulates important physiological functions of the respiratory tract.METHODS:We used mice genetically deficient in the cystathionine γ-lyase enzyme (CSE), the major H2S-generating enzyme in the lung to determine the contribution of H2S to airway disease in response to side-stream tobacco smoke (TS), and to TS /RSV co-exposure.RESULTS:Following a two-week period of exposure to TS, CSE-deficient mice (KO) showed a dramatic increase in airway hyperresponsiveness (AHR) to methacholine challenge, and greater airway cellular inflammation, compared to wild type (WT) mice. TS-exposed CSE KO mice that were subsequently infected with RSV exhibited more severe clinical disease, airway obstruction and AHR, enhanced viral replication and lung inflammation, compared to TS-exposed RSV-infected WT mice. TS-exposed RSV-infected CSE KO mice had also a significant increase in the number of neutrophils in bronchoalveolar lavage (BAL) fluid and increased levels of inflammatory cytokines and chemokines.CONCLUSION:This study demonstrates the critical contribution of the H2S-generating pathway to airway reactivity and disease following exposure to ETS alone or in combination with RSV infection.

A retrospective study of clinical features of cough variant asthma in Chinese adults

BackgroundClinical features of cough variant asthma (CVA) in Chinese adults are largely uncertain.MethodsA total of 303 patients newly diagnosed as uncontrolled asthma (symptom control and future risk of adverse outcomes), including 175 CVA and 128 classic asthma (CA), were enrolled in this retrospective survey. Clinical features including basic characteristics, pulmonary function, airway hyperresponsiveness (AHR) and cell counts of induced sputum, were compared retrospectively. All patients were classified into four inflammatory subtypes based on the counts of induced sputum eosinophils and neutrophils as eosinophilic (E), neutrophilic (N), mixed granulocytic (M), and paucigranulocytic (P) subtypes. Inflammatory subtype distribution was also compared.ResultsCompared with CA patients, CVA patients were younger (P = 0.009), had a higher prevalence of female patients (P = 0.001), higher parameter values of baseline pulmonary function (P ≤ 0.01 for all), shorter duration of disease (P = 0.002), lower AHR (P = 0.001) and lower sputum eosinophil% (P = 0.009). There was a difference in the AHR distribution as the percentage of moderate and severe AHR in CVA was significantly lower than in CA (41.72% VS 64.70%, P = 0.001). The inflammatory subtype distribution was different as the proportion of E and M subtypes in CVA was lower than in CA (56.0% vs 67.19%, P = 0.049). The proportion of subtype P was the lowest and subtype M was the highest in both CVA and CA patients. There was a similar negative correlation of sputum eosinophil% with AHR in CVA and CA (r = − 0.337, P < 0.0001 and r = − 0.27, P = 0.026, respectively), and a positive correlation between sputum eosinophil% and improvement rate of FEV1 after inhalation of bronchodilator (ΔFEV1%) (r = 0.33, P = 0.01).ConclusionsCVA patients showed a better pulmonary function and lower airway inflammation in contrast to CA patients, which may participate in the pathogenesis of chronic cough in CVA.

ITGB4 is essential for containing HDM-induced airway inflammation and airway hyperresponsiveness.

Airway epithelial cells play a significant role in the pathogenesis of asthma. Although the structural and functional defects of airway epithelial cells have been postulated to increase asthma susceptibility and exacerbate asthma severity, the mechanism and implication of these defects remain uncertain. Integrin β4 (ITGB4) is a structural adhesion molecule that is downregulated in the airway epithelium of asthma patients. In this study, we demonstrated that ITGB4 deficiency leads to severe allergy-induced airway inflammation and airway hyper-responsiveness (AHR) in mice. After house dust mite (HDM) challenge, epithelial cell-specific ITGB4-deleted mice showed increased lymphocyte, eosinophil, and neutrophil infiltration into lung compared with that of the wild-type mice. ITGB4 deficiency also resulted in increased expression of the Th2 cytokine IL-4, IL-13, and the Th17 cytokine IL-17A in the lung tissue and in the T cells after HDM challenge. The aggravated inflammation in ITGB4 defect mice was partly caused by enhanced disrupted epithelial barrier integrity after HDM stress, which induced the increased thymic stromal lymphopoietin secretion from airway epithelial cells. This study therefore demonstrates that ITGB4 plays a pivotal role in containing allergen-mediated lung inflammation and airway hyper-responsiveness in allergic asthma.

PI3K\u03b4 contributes to ER stress-associated asthma through ER-redox disturbances: the involvement of the RIDD\u2013RIG-I\u2013NF-\u03baB axis

Hyperactivation of phosphoinositol 3-kinase (PI3K) has been suggested to be a potential mechanism for endoplasmic reticulum (ER) stress-enhanced airway hyperresponsiveness, and PI3K inhibitors have been examined as asthma therapeutics. However, the regulatory mechanism linking PI3K to ER stress and related pathological signals in asthma have not been defined. To elucidate these pathogenic pathways, we investigated the influence of a selective PI3Kδ inhibitor, IC87114, on airway inflammation in an ovalbumin/lipopolysaccharide (OVA/LPS)-induced asthma model. In OVA/LPS-induced asthmatic mice, the activity of PI3K, downstream phosphorylation of AKT and activation of nuclear factor-κB (NF-κB) were all significantly elevated; these effects were reversed by IC87114. IC87114 treatment also reduced the OVA/LPS-induced ER stress response by enhancing the intra-ER oxidative folding status through suppression of protein disulfide isomerase activity, ER-associated reactive oxygen species (ROS) accumulation and NOX4 activity. Furthermore, inositol-requiring enzyme-1α (IRE1α)-dependent degradation (RIDD) of IRE1α was reduced by IC87114, resulting in a decreased release of proinflammatory cytokines from bronchial epithelial cells. These results suggest that PI3Kδ may induce severe airway inflammation and hyperresponsiveness by activating NF-κB signaling through ER-associated ROS and RIDD–RIG-I activation. The PI3Kδ inhibitor IC87114 is a potential therapeutic agent against neutrophil-dominant asthma.

Celastrol Alleviates Airway Hyperresponsiveness and Inhibits Th17 Responses in Obese Asthmatic Mice.

Severe airway hyperresponsiveness (AHR) is a clinical feature of asthma, which has been associated with obesity and has shown a poor response to standard asthma treatments such as glucocorticoids. Numerous studies have shown that Interleukin (IL)-17 producing CD4+T cells (Th17 cells), which could be inhibited by celastrol, is essential in mediating steroid-resistant AHR. The following study investigates the impact of celastrol and its mechanism on the regulation of AHR in murine model of obesity and asthma. C57BL/6 mice were sensitized by intraperitoneal injection of ovalbumin (OVA) on day 1 and 13 starting from 12th week, which was followed by aerosol OVA challenge that lasted for 30 min per daily for 7 consecutive days starting from 16th week. Diet-induced obesity (DIO) mice were fed a high fat diet (HFD) for 16 weeks. Celastrol was administrated orally for 7 consecutive days, 30 min before every challenge in DIO-OVA-induced mice. Lung functions were analyzed by measuring the airway resistance (Rn) and methacholine (MCh) AHR, while H&E staining was used to examine histological changes in the lungs. Immunohistochemistry was used to observe IL-17A protein in lung tissues; flow cytometry to detect the proportion of Th17 cells in CD4+T cells. The concentration of cytokines IL-17A in serum was assessed by standardized sandwich ELISA, while the expression of IL-17A mRNA in lung was examined by quantitative real-time RT-PCR. Briefly, our data indicated that celastrol reduced body mass in DIO-OVA-induced obesity and asthma. Both baseline Rn and MCh AHR were significantly lower in celastrol group. Moreover, celastrol treatment decreased the frequency of Th17 cell expansion and reduced the production of IL-17A in both lung and serum. To sum up, our findings indicated that Th17 and its cytokine measured in the spleen and lung were closely associated with AHR. In addition, celastrol has shown the ability to suppress AHR through Th17 inhibition in obese asthmatic mice.

The airway hyperresponsiveness to methacholine may be predicted by impulse oscillometry and plethysmography in children with well-controlled asthma

ABSTRACTObjective: Airway hyperresponsiveness (AHR) is a hallmark of asthma. Methacholine challenge test which is mostly used to confirm AHR is not routinely available. The aim of this study was to investigate the predictive values of fractional exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and plethysmography for the assessment of AHR in children with well-controlled asthma. Methods: 60 children with controlled allergic asthma aged 6–18 years participated in the study. FeNO measurement, spirometry, IOS, and plethysmography were performed. Methacholine challenge test was done to assess AHR. PC20 and dose response slope (DRS) of methacholine was calculated. Results: Mild to severe AHR with PC20 < 4 mg/ml was confirmed in 31 (51.7%) patients. Baseline FeNO and total specific airway resistance (SRtot)%pred and residual volume (RV)%pred levels in plethysmography were significantly higher and FEV1%pred, FEV1/FVC%pred, MMEF%pred values were lower in the group with PC20 < 4 mg/ml. FeNO, SRtot%pred, and RV%pred levels were found to be positively correlated with DRS methacholine. The higher baseline FeNO, frequency dependence of resistance (R5–R20) in IOS and SRtot%pred in plethysmography were found to be significantly related to DRS methacholine in linear regression analysis (β: 1.35, p = 0.046, β: 4.58, p = 0.002, and β: 0.78, p = 0.035, respectively). The cut-off points for FeNO and SRtot% for differentiating asthmatic children with PC20 < 4 mg/ml from those with PC20 ≥ 4 mg/ml were 28 ppb (sensitivity: 67.7%, specificity: 72.4%, p < 0.001) and 294.9% (sensitivity: 35.5%, specificity: 96.6%, p = 0.013), respectively. Conclusion: IOS and plethysmography may serve as reliable and practical tools for prediction of mild to severe methacholine induced AHR in otherwise “seemingly well-controlled’’ asthma.

Methacholine Challenge Test Reveals a High Prevalence of Subclinical Severe Airway Hyper-Reactivity in Children and Yound Adults with Sickle Cell Disease Which Correlates with Higher Sickle Acute Events and Acute Chest

▪Background: Although increase prevalence of airway hyper-reactivity (AHR) has been detected in children, and even adults with sickle cell disease (SCD) using methacholine provocative challenge test (MCT), AHR was not been found to be associated with clinical asthma.Hence, the clinical implications of AHR in SCD are unknown. Furthermore, AHR studies in SCD patients using MCT lack comparisons with a control population. We recently showed that increased placenta growth factor (PlGF) levels in sickle mice causes AHR by upregulating leukotriene synthesis and inflammation. We therefore designed a prospective study to determine the prevalence of AHR in children and young adults with SCD, and in unaffected siblings living in the same household as a control population, and also determine the biochemical and clinical implications of AHR in SCD.Methods: A total of 67 patients with SCD and 14 unaffected siblings of the patients enrolled on to the study for determining baseline AHR (ClinicalTrials.gov Identifier: NCT00448370). Chief eligibility criteria included a diagnosis of SCD (HbSS, HbSC or HbS b-thalassemia) confirmed by hemoglobin electrophoresis or gene sequencing, ages 5.5 years to 30 years who were able to complete pulmonary function testing and were at baseline/steady state (no acute sickle events 3 weeks prior or acute chest syndrome (ACS) 4 weeks prior). Excluded were patients taking anti-leukotriene medications within 30 days prior, although patients with SCD who had a known history of asthma but not on leukotriene inhibitors were eligible. Patients with chronic transfusions, congenital lung or heart condition, or other medical condition that could affect the pulmonary function testing were also ineligible. Unaffected siblings of the 67 enrolled SCD patients living in the same household were offered enrollment for MCT and those consenting were enrolled.Results: 64 SCD patients and 14 siblings underwent a MCT; 3 of 67 SCD patients had FEV1<70% of predicted at baseline, and therefore, for safety reasons, were not subjected to MCT. The degree of AHR was defined by the provocative concentration of methacholine that resulted in a 20% decline in FEV1 (PC20): no AHR=PC20 >16mg/mL; borderline AHR=PC20 4-16mg/mL; mild AHR=PC20 1-3mg/mL and moderate-severe AHR=PC20 <1mg/mL. All subjects were given a dose of albuterol after completion of MCT. MCT was safe in all subjects, and no AHR or acute sickle events occurred in any subject for three weeks after the MCT. Overall, 25 of 67 (37%) SCD patients had no AHR, 8 of 67 (12%) had borderline AHR (PC20 9±1.4mg/ml), 10 of 67 (15%) had mild AHR (PC20 1.72 ±0.16) and 24 of 67 (36%) had moderate-severe AHR (PC20 0.6 ±0.06). Of unaffected siblings, 10 of 14 (71%) had no AHR, 2 of 14 (14%) had borderline AHR (PC20 10±0.4) and 2 of 14 (14%) had mild AHR (PC20 1.7±0.4). Moderate to severe AHR was only seen in SCD patients and not sibling controls. Severe AHR prevalence was highest in the HbSS group. We analyzed the clinical characteristics of the SCD subjects, including acute sickle episodes, defined as admission for one of the following: pain crises, fever with or without a known source of infection, cough/wheezing/chest pain, impending acute chest syndrome, enlarged and splenic sequestration or priapism. SCD patients with AHR had significantly higher (P<0.05) admissions from acute sickle episodes (2.7±0.1) and acute chest syndrome (1.5±0.15). We next assessed PlGF and leukotriene levels in SCD subjects. PlGF levels were not quantifiable due to presence of hemolysis, which confounds PlGF ELISA. However, we found a trend towards higher (1.3-2 fold) expression of PlGF-induced target genes (VEGF, IL-1β, IL-8, CCL2) in the mononuclear cells of patients with severe AHR; Also, circulating cysteinyl leukotriene D4 levels in their plasma were significantly higher.Conclusions: There was a higher prevalence of mild to severe AHR (51%) in patients with SCD, compared to a 14% prevalence of mild AHR in siblings living in the same household. The higher degree of AHR was associated with increased SCD morbidity - increased rates of admission from ACS and pain crisis, when compared to those with no AHR. AHR was associated with higher leukotrienes and a trend towards higher PlGF target gene induction. Together, our data suggests that AHR may be a biomarker for SCD morbidity, and may also be a therapeutic target, since blockade of PlGF or leukotriene synthesis in patients with severe AHR may reduce SCD morbidity. DisclosuresNo relevant conflicts of interest to declare.

Marijuana smoke induces severe pulmonary hyperresponsiveness, inflammation, and emphysema in a predictive mouse model not via CB1 receptor activation.

Sporadic clinical reports suggested that marijuana smoking induces spontaneous pneumothorax, but no animal models were available to validate these observations and to study the underlying mechanisms. Therefore, we performed a systematic study in CD1 mice as a predictive animal model and assessed the pathophysiological alterations in response to 4-mo-long whole body marijuana smoke with integrative methodologies in comparison with tobacco smoke. Bronchial responsiveness was measured with unrestrained whole body plethysmography, cell profile in the bronchoalveolar lavage fluid with flow cytometry, myeloperoxidase activity with spectrophotometry, inflammatory cytokines with ELISA, and histopathological alterations with light microscopy. Daily marijuana inhalation evoked severe bronchial hyperreactivity after a week. Characteristic perivascular/peribronchial edema, atelectasis, apical emphysema, and neutrophil and macrophage infiltration developed after 1 mo of marijuana smoking; lymphocyte accumulation after 2 mo; macrophage-like giant cells, irregular or destroyed bronchial mucosa, goblet cell hyperplasia after 3 mo; and severe atelectasis, emphysema, obstructed or damaged bronchioles, and endothelial proliferation at 4 mo. Myeloperoxidase activity, inflammatory cell, and cytokine profile correlated with these changes. Airway hyperresponsiveness and inflammation were not altered in mice lacking the CB1 cannabinoid receptor. In comparison, tobacco smoke induced hyperresponsiveness after 2 mo and significantly later caused inflammatory cell infiltration/activation with only mild emphysema. We provide the first systematic and comparative experimental evidence that marijuana causes severe airway hyperresponsiveness, inflammation, tissue destruction, and emphysema, which are not mediated by the CB1 receptor.

Clinical predictors of remission and persistence of adult-onset asthma

Adult-onset asthma is an important but relatively understudied asthma phenotype and little is known about its natural course and prognosis. The remission rate is believed to be low, and it is still obscure which factors predict remission or persistence of the disease. This study sought to determine the remission rate and identify predictors of persistence and remission of adult-onset asthma. Two hundred adult patients with recently diagnosed (<1year) asthma were recruited from secondary and tertiary pulmonary clinics and prospectively followed for 5years. Clinical, functional, and inflammatory parameters were assessed at baseline and at yearly visits. Asthma remission was defined as absence of asthma symptoms for ≥1year and no asthma medication use for ≥1year. Descriptive statistics and logistic regression analysis were performed. Five-year follow-up data of 170 patients (85%) was available. Of these, 27 patients (15.9%) experienced asthma remission. Patients with asthma persistence were older, had worse asthma control, required higher doses of inhaled corticosteroids, had more severe airway hyperresponsiveness, more often nasal polyps, and higher levels of blood neutrophils as compared to patients who experienced clinical remission. In a multivariable logistic regression analysis, only moderate to severe bronchial hyperresponsiveness and nasal polyps were independent predictors of asthma persistence. Patients with these 2 characteristics had <1% chance of asthma remission. One in 6 patients with adult-onset asthma experiences remission within the first 5years of the disease. Inpatients with moderate to severe bronchial hyperresponsiveness and nasal polyposis, the chance of remission is close to zero.