Airway Challenge Research Articles

Isoimperatorin attenuates airway inflammation and mucus hypersecretion in an ovalbumin-induced murine model of asthma

Isoimperatorin (IMP), an active natural furocoumarin, has numerous pharmacologic effects, including anti-inflammatory, analgesic, antispasmodic, and anticancer activities. This study aimed to evaluate the preventive activity of IMP in an ovalbumin (OVA)-induced murine model of asthma and to investigate its possible molecular mechanisms. Female BALB/c mice were sensitized on days 0 and 14 via intraperitoneal injection of 20μg OVA. On days 21–23 after the initial sensitization, the mice received an airway challenge with OVA (1% w/v in PBS) for 1h; meanwhile, IMP (10 or 30mg/kg once daily) was administered by gavage on days 18–23. Our results revealed that IMP significantly lowered the productions of interleukin (IL)-4, IL-5, IL-13, eotaxin, and immunoglobulin (Ig)E in bronchoalveolar lavage fluid (BALF), plasma, or lung tissues. Histological studies showed that IMP inhibited OVA-induced inflammatory cell infiltration and mucus production in the respiratory tract. In addition, pretreatment with IMP suppressed the activation of p38 mitogen-activated protein kinase (p38 MAPK), extracellular-signal-regulated kinases 1/2 (ERK1/2), and nuclear factor-κB (NF-κB). Together, these results suggest that IMP effectively inhibits airway inflammation and mucus hypersecretion by downregulating the levels of Th2 cytokines and inhibiting NF-κB and MAPK pathways.

Diagnosing Exercise Induced Bronchoconstriction

Eucapnic Voluntary Hyperpnoea (EVH) is a sensitive indirect airway challenge to assist in the diagnosis of Exercise Induced Bronchoconstriction (EIB). However, it has been previously reported that a positive EVH challenge may not necessarily predictive a positive exercise challenge (EX). EX have previously shown varying sensitivity due to differences in control over the inspired air water content, with studies being conducted in ambient lab conditions or using medical grade dry air. PURPOSE: To compare the EVH challenge with an EX in a controlled dry air environment, to see if a standardised EX can be used in the diagnosis or EIB. METHODS: Thirty-one healthy participants (10 female; 21 males, age 36 ± 10 yrs, exercising 7.7 ± 3.0 hrs per week) gave informed consent. Eight had a history of asthma but were not taking preventative medication. Participants completed an EVH and an EX on a cycle ergometer in a randomised order. The EVH required participants to breathe a gas mixture (5% CO2, 21% O2 and 74% N2, <2%RH) at a rate equivalent to 85% predicted MVV. The EX was conducted in an environmental chamber (16°c, 25%RH). Following a 4-min set warm up participants completed 6-mins of cycling at a work rate associated with 85% HRmax. Tests were deemed positive if there was a fall in FEV1 of ≥ 10% following the challenge. Results were analysed using paired t-tests and Pearson’s correlation and are presented as mean ± SD. RESULTS: Seven participants were positive to EVH. Of these, only two had a positive response to Ex. No differences in baseline FEV1 between EVH and EX were found (EVH:4.06 ± 0.79, EX: 4.06 ± 0.77 L, p = 0.746). There was a strong correlation between the % fall in FEV1 post EVH and EX (r = 0.520, p = 0.003). However, the % fall in FEV1 post EVH was significantly greater that post EX (EVH: -7.5 ± 5.4, EX: -2.0 ± 3.8 %, p < 0.001). The total amount of air expired was significantly higher in 6 mins EVH compared to 6 mins EX (EVH: 686.5 ± 141.7, EX: 617.9 ± 83.1 L, p = 0.002). CONCLUSION: A positive EVH challenge may not be predictive of a positive Exercise Challenge in a dry environment. EVH may have a greater sensitivity due to the lower water content of inspired air and a greater VE. This suggests that a mild positive EVH challenge (a fall in FEV1 of 10-15%), may not be predictive of EIB.

Parasternal intercostal muscle activity during methacholine-induced bronchoconstriction.

What is the central question of this study? The parasternal intercostal electromyogram (EMGpara) is known to provide an accurate, non-invasive index of respiratory load-capacity balance. Although relationships between EMGpara and both airflow obstruction and hyperinflation have been shown, the independent contribution of each factor has not been examined. What is the main finding and its importance? Reductions in airway calibre and inspiratory capacity along with increases in EMGpara were induced via methacholine challenge. A strong inverse relationship was observed between EMGpara and airway obstruction, with no influence of inspiratory capacity. These data suggest that EMGpara is more strongly influenced by airway calibre than by changes in end-expiratory lung volume during airway challenge testing. Neural respiratory drive, measured via the parasternal intercostal electromyogram (EMGpara), provides a non-invasive index of the load-capacity balance of the respiratory muscle pump. Previous studies in patients with obstructive lung disease have shown strong relationships between EMGpara and the extent of both airflow obstruction and hyperinflation. The relative influence of the two factors has not, however, been described. Airflow obstruction was induced via methacholine challenge testing in 25 adult humans. Forced expiratory volume in 1 s (FEV1 ) and surface EMGpara during tidal breathing were measured after each dose, with 20 of the participants also undergoing measurements of inspiratory capacity (IC) at each stage. Linear mixed model analysis was used to assess dose-wise changes in FEV1 and EMGpara, and thereafter to determine the influence of changes in FEV1 and IC on change in EMGpara. Median (interquartile range) FEV1 decreased significantly [from 96.00 (80.00-122.30) to 67.80 (37.98-92.27)% predicted, P<0.0001] and EMGpara increased significantly [from 5.37 (2.25-8.92) to 6.27 (3.37-19.60) μV, P<0.0001] from baseline to end of test. Linear mixed model analysis showed a significant interaction between methacholine dose and induced change in EMGpara, with an increase in EMGpara of 0.24 (95% confidence interval 0.11-0.37) μV per methacholine dose2 . Change in FEV1 further influenced this relationship [increase in slope of 0.002 (0.004-0.001) μVdose-2 per % predicted fall in FEV1 , P=0.011], but not with change in IC. These data suggest that bronchoconstriction exerts a more potent influence on levels of EMGpara than changes in end-expiratory lung volume during methacholine challenge.

In vivo targeting of protein antigens to dendritic cells using anti-DEC-205 single chain antibody improves HIV Gag specific CD4+ T cell responses protecting from airway challenge with recombinant vaccinia-gag virus.

IntroductionTargeting antigens to dendritic cells (DCs) in vivo via a DC‐restricted endocytic receptor, DEC205, has been validated to enhance immunity in several vaccine platforms. Particularly atttractive is selected delivery of proteins to DCs in vivo because it enables proteins to be more immunogenic and provides a cheaper and effective way for repeated immunizations.MethodsIn this study, we tested the efficacy of a single chain antibody to DEC205 (scDEC) to deliver protein antigens selectively to DCs in vivo and to induce protective immunity.ResultsIn comparison to soluble Ovalbumin (OVA) antigen, when recombinant scDEC:OVA protein was injected subcutaneously (s.c.) into mice, the OVA protein was selectively presented by DCs to both TCR transgenic CD8+ and CD4+ T cells approximately 500 and 100 times more efficient than soluble OVA, respectively, and could persist for seven days following s.c. injection of the scDEC205:OVA. Similarly selective targeting of HIV Gag P24 to DCs in vivo using scDEC‐Gag protein plus polyICLC vaccine resulted in strong, long lasting, polyfuntional CD4+ T cells in mice which were protective against airway challenge by a recombinant vaccinia‐gag virus.ConclusionThus targeting protein antigens to DCs using scDEC can be used either alone or in combination with other strategies for effective immunization.

Safety and benefits of inhaled hypertonic saline following airway challenges with endotoxin and allergen in asthmatics

ABSTRACTObjective: To determine whether induced sputum (IS) with hypertonic saline inhalation is safe to use in asthmatics within 24 hours of two commonly used airway challenges, namely endotoxin and dust mite allergen, and to assess whether IS can enhance mucociliary clearance (MCC) rates in asthmatics. Methods: IS (three 7-minute inhalation periods of 3%, 4%, and 5% hypertonic saline) was employed before (N = 29) and within 24 hours of inhaled challenges with endotoxin (N = 13) and dust mite allergen (N = 12) in a cohort of mild to moderate asthmatics. Safety was assessed by lung function (Forced Expiratory Volume in 1 second; FEV1) and MCC was measured using a radiolabeled gamma scintigraphy method (Tcm99 sulfur colloid). IS was performed pre and post MCC. Results: No significant lung function decrement was observed before or after inhaled challenges with endotoxin or dust mite allergen. IS significantly enhanced MCC rates before and after inhaled endotoxin challenge. Conclusion: Based on a small cohort, IS is safe to use in mild to moderate asthmatics before and within 24 hours of inhaled challenges with endotoxin and dust mite allergen. Furthermore, IS has beneficial effects on host defense function in asthmatics by enhancing MCC rates.

Recombinant protein CPSIT_0846 induces protective immunity against Chlamydia psittaci infection in BALB/c mice

Chlamydia psittaci is an obligate intracellular bacteria that causes respiratory disease in poultry and humans. Currently, there are no licensed vaccines against chlamydial infection in humans. The transmembrane head protein CPSIT_0846 of C. psittaci is a putative member of the larger Inc protein family. In this study, we investigated immunogenicity and protective efficacy of the recombinant CPSIT_0846 protein in BALB/c mice. Mice immunized with CPSIT_0846 developed strong T-lymphocyte responses that were recalled by the immunogen CPSIT_0846 in an in vitro restimulation assay. These T cells displayed a strong Th1-biased cytokine profile with high levels of IFN-γ. At the same time, a strong humoral immune response was also detected in the immunized mice with high titers of Chlamydia psittaci-specific serum IgG antibodies. More importantly, the robust immune responses correlated well with significantly reduced chlamydial burden and inflammatory pathology in the mouse lungs upon an airway challenge infection. The above results together suggest that the CPSIT_0846 protein may be a potential vaccine candidate antigen for inducing protection against C. psittaci infection and disease in the airway.

Entire Course Monitoring and Evaluation of Asthma Attack Following Allergen Airway Challenge In A Rat Model

Entire Course Monitoring and Evaluation of Asthma Attack Following Allergen Airway Challenge In A Rat Model

Detection of smoothly distributed spatial outliers, with applications to identifying the distribution of parenchymal hyperinflation following an airway challenge in asthmatics.

Methacholine challenge tests are used to measure changes in pulmonary function that indicate symptoms of asthma. In addition to pulmonary function tests, which measure global changes in pulmonary function, computed tomography images taken at full inspiration before and after administration of methacholine provide local air volume changes (hyper-inflation post methacholine) at individual acinar units, indicating local airway hyperresponsiveness. Some of the acini may have extreme air volume changes relative to the global average, indicating hyperresponsiveness, and those extreme values may occur in clusters. We propose a Gaussian mixture model with a spatial smoothness penalty to improve prediction of hyperresponsive locations that occur in spatial clusters. A simulation study provides evidence that the spatial smoothness penalty improves prediction under different data-generating mechanisms. We apply this method to computed tomography data from Seoul National University Hospital on five healthy and ten asthmatic subjects. Copyright © 2017 John Wiley & Sons, Ltd.

An unusual airway challenge in a patient with acromegaly.

An unusual airway challenge in a patient with acromegaly.

56 A Novel Method to Describe Emergency Airway Challenges, Techniques, and Success Rates: A One-Year Experience in a Busy County Emergency Department

56 A Novel Method to Describe Emergency Airway Challenges, Techniques, and Success Rates: A One-Year Experience in a Busy County Emergency Department

Murine models of epicutaneous sensitization to protease allergen, which leads to airway eosinophilia upon subsequent airway challenge

Murine models of epicutaneous sensitization to protease allergen, which leads to airway eosinophilia upon subsequent airway challenge

Adeno-Associated Virus Serotype 9-Expressed ZMapp in Mice Confers Protection Against Systemic and Airway-Acquired Ebola Virus Infection.

Adeno-associated viral vectors can be used as a platform for delivering biological countermeasures against pandemic and biological threats. We show that vector delivery of two antibody components of the ZMapp product is effective in mice against systemic and airway challenge with a mouse-adapted strain of Ebola virus. This platform provides a generic manufacturing solution and overcomes some of the delivery challenges associated with repeated administration of the protective protein.

The protective role of vitamin D3 in a murine model of asthma via the suppression of TGF-β/Smad signaling and activation of the Nrf2/HO-1 pathway.

Asthma is a common worldwide health burden, the prevalence of which is increasing. Recently, the biologically active form of vitamin D3, 1,25-dihydroxyvitamin D3, has been reported to have a protective role in murine asthma; however, the molecular mechanisms by which vitamin D3 attenuates asthma-associated airway injury remain elusive. In the present study, BALB/c mice were sensitized to ovalbumin (OVA) and were administered 100 ng 1,25-dihydroxyvitamin D3 (intraperitoneal injection) 30 min prior to each airway challenge. The inflammatory responses were measured by ELISA, airway damage was analyzed by hematoxylin and eosin staining, airway remodeling was analyzed by Masson staining and periodic acid-Schiff staining, markers of oxidative stress were measured by commercial kits, and the expression levels of α-smooth muscle actin (α-SMA) and the activity of the NF-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) and the transforming growth factor-β (TGF-β)/Smad signaling pathways were measured by immunohistochemistry and western blotting. The results demonstrated that OVA-induced airway inflammation and immunoglobulin E overexpression were significantly reduced by vitamin D3 treatment. In addition, treatment with vitamin D3 decreased α-SMA expression, collagen deposition and goblet cell hyperplasia, and inhibited TGF-β/Smad signaling in the asthmatic airway. The upregulated levels of malondialdehyde, and the reduced activities of superoxide dismutase and glutathione in OVA-challenged mice were also markedly restored following vitamin D3 treatment. Furthermore, treatment with vitamin D3 enhanced activation of the Nrf2/HO-1 pathway in the airways of asthmatic mice. In conclusion, these findings suggest that vitamin D3 may protect airways from asthmatic damage via the suppression of TGF-β/Smad signaling and activation of the Nrf2/HO-1 pathway; however, these protective effects were shown to be accompanied by hypercalcemia.

Mechanical Ventilation Alters the Development of Staphylococcus aureus Pneumonia in Rabbit.

Ventilator-associated pneumonia (VAP) is common during mechanical ventilation (MV). Beside obvious deleterious effects on muco-ciliary clearance, MV could adversely shift the host immune response towards a pro-inflammatory pattern through toll-like receptor (TLRs) up-regulation. We tested this hypothesis in a rabbit model of Staphylococcus aureus VAP. Pneumonia was caused by airway challenge with S. aureus, in either spontaneously breathing (SB) or MV rabbits (n = 13 and 17, respectively). Pneumonia assessment regarding pulmonary and systemic bacterial burden, as well as inflammatory response was done 8 and 24 hours after S. aureus challenge. In addition, ex vivo stimulations of whole blood taken from SB or MV rabbits (n = 7 and 5, respectively) with TLR2 agonist or heat-killed S. aureus were performed. Data were expressed as mean±standard deviation. After 8 hours of infection, lung injury was more severe in MV animals (1.40±0.33 versus [vs] 2.40±0.55, p = 0.007), along with greater bacterial concentrations (6.13±0.63 vs. 4.96±1.31 colony forming units/gram, p = 0.002). Interleukin (IL)-8 and tumor necrosis factor (TNF)-αserum concentrations reached higher levels in MV animals (p = 0.010). Whole blood obtained from MV animals released larger amounts of cytokines if stimulated with TLR2 agonist or heat-killed S. aureus (e.g., TNF-α: 1656±166 vs. 1005±89; p = 0.014). Moreover, MV induced TLR2 overexpression in both lung and spleen tissue. MV hastened tissue injury, impaired lung bacterial clearance, and promoted a systemic inflammatory response, maybe through TLR2 overexpression.

Selective COX-2 Inhibition Exerts No Negative Effects on Peripheral Blood Lymphocytes in Allergic Asthmatics

Background: Selective inhibition of cyclooxygenase-2 (COX-2) reduces the production of prostaglandin E₂ (PGE₂), which can have both pro- and anti-inflammatory effects on allergic inflammation. Moreover, in vitro PGE₂ has been shown to affect inflammation through the modulation of lymphocyte responses. Methods: Sixteen subjects with mild allergic asthma were recruited to a two-period cross-over study: one treatment period with the selective COX-2 inhibitor etoricoxib and one without. Each treatment period ended with an airway challenge with the patient's relevant allergen. Antigen-specific proliferation with the major cat allergen, Fel d 1, was analysed in PBMCs. CD4+ T cells were phenotyped using flow cytometry, and mRNA expression of FOXP3 in anti-CD3-stimulated CD4+ cells were analysed. Results: No significant impact of in vivo inhibition of COX-2 was detected on the proportion of Th1, Th2, or Treg cells in peripheral blood. Likewise, the treatment had minor effects on the stimulated expression of FOXP3 mRNA in CD4+ T cells. Proliferation of PBMCs to the major cat allergen Fel d 1 was slightly reduced by etoricoxib treatment in cat-allergic patients. Conclusions: Short-term treatment with the COX-2 inhibitor etoricoxib had a minor impact on T-cell responses, supporting its safe use also in subjects exposed to triggers of lymphocyte activation.

Pediatric Airway Management and Prehospital Patient Safety: Results of a National Delphi Survey by the Children's Safety Initiative-Emergency Medical Services for Children.

The objective of this study was to determine what aspects of prehospital pediatric airway management may contribute to patient safety events. We conducted a 3-phase Delphi survey in prehospital professionals across the United States to identify potential contributors to patient safety events. Respondents ranked how likely factors were to contribute on a 9-point Likert-type scale and were allowed to elaborate through open-ended questions. Analysis was conducted using a mixed-methods approach, including Likert-type responses and open-ended questions which were analyzed for specific themes. All 3 phases of the survey were completed by 492 participants; 50.8% of respondents were paramedics, 22% were emergency medical technician-basics/first responders, and 11.4% were physicians. Seventy-five percent identified lack of experience with advanced airway management, and 44% identified medical decision making regarding airway interventions as highly likely to lead to safety events. Within the domain of technical skills, advanced airway management was ranked in the top 3 contributors to safety events by 71% of participants, and bag-mask ventilation by 18%. Qualitative analysis of questions within the domains of equipment and technical skills identified endotracheal intubation as the top contributor to safety events, with bag-mask ventilation second. In the domains of assessment and decision making, respiratory assessment and knowing when to perform an advanced airway were ranked most highly. This national Delphi survey identified lack of experience with pediatric airway management and challenges in decision making in advanced airway management as high risk for safety events, with endotracheal intubation as the most likely of these.

Airway management and training in obstetric anaesthesia.

Airway management and failed intubation in the pregnant woman requires unique considerations, which differ from the nonpregnant patient. Factors that influence airway management in this setting include anatomical and physiological changes in pregnancy, environmental factors as well as training matters. In addition, surgery is often being performed with extreme urgency, which requires rapid decision-making process that takes into account safe outcome of mother and baby. The purpose of this review is to focus on recent developments that address these exceptional airway challenges in obstetrics. The first national UK obstetric difficult airway guidelines that have been recently published, are based around algorithms that deal with induction of general anaesthesia, failed intubation and front-of-the-neck access. As well as emphasising good practice in planning, preparation, and rapid sequence induction (RSI) technique, they outline how to make a provisional plan prior to the induction of general anaesthesia, on whether to awaken or continue general anaesthesia, should failed intubation occur. Current recommendations aim to move away from the traditional and outdated obstetric RSI technique to introduce changes, which are in keeping with anaesthetic practice in the nonpregnant patients. Such changes include the choice of induction agent and muscle relaxant, preoxygenation techniques, and mask ventilation during RSI; and the early release of cricoid pressure should failed intubation occur. Recent advances and recommendations in the management of the obstetric airway should help to bring consistency of clinical practice, reduce adverse events, and standardize teaching by providing a structure for teaching and training on failed tracheal intubation in obstetrics. Opportunities during elective caesarean sections and simulation should be used as teaching tools to improve anaesthetists' and team performance during a crisis.

The role of type 2 innate lymphoid cells in RSV-induced asthma exacerbation.

Abstract Respiratory viral infections cause devastating airway inflammation and remodeling in asthmatic children and adults. Type 2 innate lymphoid cells (ILC2) have been characterized individually in both asthma and viral infections. We hypothesize that ILC2 are activated by IL-33 in our model, and thereby enhance the asthmatic phenotype in the lung. Asthma induction was performed in eight week old, female BALB/c mice using ovalbumin (OVA) sensitization and airway challenge. After the last airway challenge, mice were infected with RSV (3,250 TCID50 U/mouse). Lungs were collected for ILC2 sorting, immune cell quantitation, and analysis of IL-4, IL-13, IL-33 and IL-25 on days 1–4 of infection. A subset of lungs were collected and fixed for histological analysis. Results show that mucus production (PAS+ cells) and lymphocytic recruitment were enhanced with RSV infection and asthma. The expression of MUC5AC, CLCA3, IL-25 and IL-33 mRNA levels were increased at least two-fold in the lungs of OVA+RSV mice compared to RSV-infected alone. We detected comparable numbers of ILC2 in BAL fluid from both OVA+ and OVA+RSV mice, yet an evaluation of total lung lymphocytes yielded more ILC2 in the OVA+RSV mice as compared to OVA alone. ILC2 from OVA+RSV mice were sorted and treated with IL-33 for 24 hours. These cells produced greater IL-4 mRNA than cells isolated from OVA only mice. Our results describe a potential role for ILC2 in the exacerbation of asthma with RSV infection. Future studies are planned to determine the exact contribution of ILC2 to type 2 immunity and pulmonary function in our asthma-viral infection model.

Subcutaneous Allergic Sensitization to Protease Allergen Is Dependent on Mast Cells but Not IL-33: Distinct Mechanisms between Subcutaneous and Intranasal Routes.

Protease activity of papain, a plant-derived occupational allergen homologous to mite major allergens, is essential to IgE/IgG1 production and lung eosinophilia induced by intranasal papain administration in mice, and IL-33 contributes to these responses. In this work, we investigate skin and Ab responses induced by s.c. papain administration into ear lobes and responses induced by subsequent airway challenge with papain. Subcutaneous papain injection induced swelling associated with increased epidermal thickness, dermal inflammation, serum IgE/IgG1 responses, and Th2 cytokine production in draining lymph node cells restimulated in vitro. These responses were markedly less upon s.c. administration of protease inhibitor-treated papain. Results obtained by using mast cell-deficient mice and reconstitution of tissue mast cells suggested the contribution of mast cells to papain-specific IgE/IgG1 responses and eosinophil infiltration. The responses were equivalent between wild-type and IL-33(-/-) mice. After the subsequent airway challenge, the s.c. presensitized wild-type mice showed more severe lung eosinophilia than those without the presensitization. The presensitized IL-33(-/-) mice showed modest lung eosinophilia, which was absent without the presensitization, but its severity and IgE boost by the airway challenge were markedly less than the presensitized wild-type mice, in which protease activity of inhaled papain contributed to the responses. The results suggest that mechanisms for the protease-dependent sensitization differ between skin and airway and that cooperation of mast cell-dependent, IL-33-independent initial sensitization via skin and protease-induced, IL-33-mediated mechanism in re-exposure via airway to protease allergens maximizes the magnitude of the transition from skin inflammation to asthma in natural history of progression of allergic diseases.

Neuro-immune interactions in chemical-induced airway hyperreactivity.

Asthma may be induced by chemical sensitisers, via mechanisms that are still poorly understood. This type of asthma is characterised by airway hyperreactivity (AHR) and little airway inflammation. Since potent chemical sensitisers, such as toluene-2,4-diisocyanate (TDI), are also sensory irritants, it is suggested that chemical-induced asthma relies on neuro-immune mechanisms.We investigated the involvement of transient receptor potential channels (TRP) A1 and V1, major chemosensors in the airways, and mast cells, known for their ability to communicate with sensory nerves, in chemical-induced AHR.In vitro intracellular calcium imaging and patch-clamp recordings in TRPA1- and TRPV1-expressing Chinese hamster ovarian cells showed that TDI activates murine TRPA1, but not TRPV1. Using an in vivo model, in which an airway challenge with TDI induces AHR in TDI-sensitised C57Bl/6 mice, we demonstrated that AHR does not develop, despite successful sensitisation, in Trpa1 and Trpv1 knockout mice, and wild-type mice pretreated with a TRPA1 blocker or a substance P receptor antagonist. TDI-induced AHR was also abolished in mast cell deficient Kit(Wsh) (/Wsh) mice, and in wild-type mice pretreated with the mast cell stabiliser ketotifen, without changes in immunological parameters.These data demonstrate that TRPA1, TRPV1 and mast cells play an indispensable role in the development of TDI-elicited AHR.