Inhalation Challenge Research Articles

An O-Antigen Glycoconjugate Vaccine Produced Using Protein Glycan Coupling Technology Is Protective in an Inhalational Rat Model of Tularemia.

There is a requirement for an efficacious vaccine to protect people against infection from Francisella tularensis, the etiological agent of tularemia. The lipopolysaccharide (LPS) of F. tularensis is suboptimally protective against a parenteral lethal challenge in mice. To develop a more efficacious subunit vaccine, we have used a novel biosynthetic technique of protein glycan coupling technology (PGCT) that exploits bacterial N-linked glycosylation to recombinantly conjugate F. tularensis O-antigen glycans to the immunogenic carrier protein Pseudomonas aeruginosa exoprotein A (ExoA). Previously, we demonstrated that an ExoA glycoconjugate with two glycosylation sequons was capable of providing significant protection to mice against a challenge with a low-virulence strain of F. tularensis. Here, we have generated a more heavily glycosylated conjugate vaccine and evaluated its efficacy in a Fischer 344 rat model of tularemia. We demonstrate that this glycoconjugate vaccine protected rats against disease and the lethality of an inhalational challenge with F. tularensis Schu S4. Our data highlights the potential of this biosynthetic approach for the creation of next-generation tularemia subunit vaccines.

Are high- and low-molecular-weight sensitizing agents associated with different clinical phenotypes of occupational asthma?

High-molecular-weight (HMW) proteins and low-molecular-weight (LMW) chemicals can cause occupational asthma (OA) although few studies have thoroughly compared the clinical, physiological, and inflammatory patterns associated with these different types of agents. The aim of this study was to determine whether OA induced by HMW and LMW agents shows distinct phenotypic profiles. Clinical and functional characteristics, and markers of airway inflammation were analyzed in an international, multicenter, retrospective cohort of subjects with OA ascertained by a positive inhalation challenge response to HMW (n=544) and LMW (n=635) agents. Multivariate logistic regression analysis showed significant associations between OA caused by HMW agents and work-related rhinitis (OR [95% CI]: 4.79 [3.28-7.12]), conjunctivitis (2.13 [1.52-2.98]), atopy (1.49 [1.09-2.05]), and early asthmatic reactions (2.86 [1.98-4.16]). By contrast, OA due to LMW agents was associated with chest tightness at work (2.22 [1.59-3.03]), daily sputum (1.69 [1.19-2.38]), and late asthmatic reactions (1.52 [1.09-2.08]). Furthermore, OA caused by HMW agents showed a higher risk of airflow limitation (1.76 [1.07-2.91]), whereas OA due to LMW agents exhibited a higher risk of severe exacerbations (1.32 [1.01-1.69]). There were no differences between the two types of agents in the baseline sputum inflammatory profiles, but OA caused by HMW agents showed higher baseline blood eosinophilia and a greater postchallenge increase in fractional nitric oxide. This large cohort study describes distinct phenotypic profiles in OA caused by HMW and LMW agents. There is a need to further explore differences in underlying pathophysiological pathways and outcome after environmental interventions.

The leaky lung test: a pilot study using inhaled mannitol to measure airway barrier function in asthma

Objective: Airway epithelial barrier dysfunction is emerging as an important feature of asthma pathogenesis, but this is difficult to measure in individual subjects. We aimed to develop a noninvasive way to measure airway permeability in asthma. Methods: Healthy controls and subjects with mild asthma inhaled dry powder mannitol in a dose-escalating manner on two separate occasions, stopping at 155 mg or 315 mg. Serum mannitol levels were measured at baseline and then 30, 90, and 150 min after mannitol inhalation. Mannitol absorption was compared with measurements of airflow obstruction (FEV1) and airway inflammation (FeNO). Results: Serum mannitol levels increased in a time- and dose-dependent manner in both healthy control and subjects with asthma. There were no significant differences in mannitol absorption when comparing healthy controls and subjects with asthma. Mannitol absorption did not correlate with markers of airway obstruction or inflammation. Conclusions: Measuring serum concentrations of mannitol after inhalation challenge can potentially provide insights into airway barrier function in asthma.

T CELL-INDUCED BRONCHOCONSTRICTION IN MICE

Introduction To investigate a role of helper T (Th) cells in asthma, T cell-transfer model was analyzed for late phase asthmatic responses. Methods Ovalbumin (OVA) specific Th clones were derived from splenocytes of DO11.10 transgenic mice expressing T cell receptor specific for OVA/H-2d. Th clones were adoptively transferred into unprimed mice. After intranasal or inhalation challenge with OVA, airway resistance was continuously monitored by either unrestrained whole body plethysmography (BUXCO) or resistance/compliance analyzer under anesthetized condition. Supernatants of stimulated Th clones were analyzed for contractile activity using collagen gels embedded with murine primary bronchial smooth muscle cells. Effects of H1R and LTR1 antagonist were analyzed both in vitro and in vivo. Results When unprimed mice were transferred with Th clones, T5-1, T6-2, T6-4, and T6-7, Penh values were significantly increased 6 hr after OVA challenge. In contrast, mice transferred with other Th clones, BF7, T6-1, or T6-10 did not show any change. Airflow limitation was confirmed by a direct measurement of airway resistance under anesthetized, restrained, and intubated conditions. The airflow limitation was also efficiently induced by the challenge with T cell epitope peptide, OVA323-339. Contractile activity was detected in the supernatants of T6-2 stimulated with immobilized anti-CD3. T cell-induced contraction was not affected by H1R or LTR1 antagonist. Conclusions Activation of Th cells resulted in an airflow limitation besides eosinophilic inflammation, AHR, and mucous hyperplasia. T cell-derived bronchoconstrictor might be a target for treatment-resistant asthma.

Pearls and pitfalls in the diagnosis of cough variant asthma.

Cough alone may sometimes be the sole presenting symptom of asthma. Patients experience cough without wheeze or shortness of breath and with normal baseline pulmonary function test results. These patients do, however, demonstrate bronchial hyperreactivity. They also respond to specific traditional asthma therapy. These patients are considered to have a specific asthma phenotype: cough variant asthma (CVA).In prospective studies of patients with chronic cough, an average of 25% have CVA. Patients have chronic cough, normal baseline pulmonary function tests, positive bronchial inhalation challenge results, and response to specific asthma therapy. What makes these patients cough is still unknown. The cough reflex is complex. The specific cause of cough in CVA may be similar to cough mechanisms seen in typical bronchial asthma.All therapies for typical bronchial asthma have been successful in controlling cough in patients with CVA. The overall prognosis of CVA is excellent, with most patients requiring chronic inhaled corticosteroid therapy.

Pulmonary toxicity following inhalation exposure to VX in anesthetized rats: Possible roles for compromised immunity and oxidative stress-induced lung injury

The nerve agent VX is one of the most deadly threat agents available in weapons stockpiles for intentional release. While mostly considered a percutaneous toxicant, it can be fatal when aerosolized. The objective of this study was to investigate toxic responses in the lung up to two weeks following a single 10-minute exposure to inhaled VX. Anesthetized rats were exposed singly and only once to VX. The nebulization rate in this system was 0.2–0.3 ml per minute with the delivery of a consistent particle size of 2.1 µm. Following exposure, all rats were removed from the ventilator and allowed to recover in the glovebox for 10–15 minutes. Results showed that inhaled VX altered several respiratory parameters and caused increased lung resistance up to 6 h post-exposure (PE). There was a trending increase in SOD and xanthine oxidoreductase (XOR) activities, both of which are indicative of oxidative stress. Based on increased lung tissue p38 signaling, MAP kinase expression was activated after VX exposure. IL-6 expression was also increased at 6 h post-inhalation for the 31.6 mg/m3 exposed group. Innate survival response mechanisms in rats may be present due to increased lung tissue mRNA AChE expression 6 h after exposure. Immunohistochemistry showed reduced staining for surfactant D and increased expression of iNOS, indicating that the activation of •NO precursor pathways. Bronchoalveloar lavage fluid (BALF) results from 1 h to 2 weeks PE show that inflammatory cells are highly active as evidenced by the increased production of cytokines and chemokines. This is the first study linking VX-induced lung injury to a possible innate survival amplification of AChE and possibly compromised immune function. These results could supplement medical treatment strategies with regard to therapeutic approaches against VX inhalational challenge.

San-Ao Decoction () Regulates Urine Volume on Bronchial Asthma Model Mice.

To observe the effect of San-Ao Decoction (, SAD) on water metabolism of bronchial asthra model mice. Forty-five female BALB/c mice were randomly divided into control, model and SAD groups by a random number table, 15 mice in each group. A composite method with ovalbumin (OVA) sensitization and challenge was developed to establish bronchial asthma model. Mice in the control group were intraperitoneally injected with distilled water without aerosol inhalation challenge. On day 15-22, 0.3 mL SAD was administered via gastric route in SAD group, one time per day, while an equivalent volume of normal saline was used for gastric administration in the control and model groups. Changes in airway resistance in the inspiratory phase (RI-R-Area) were detected using an AniRes2005 system, and 5-h urine output was collected by metabolic cages. Histopathological changes in lung and kidney were observed by hematoxylin-eosin staining. mRNA expressions of aquaporin (AQP) 1 and AQP2 in kidney were detected by reverse transcription-polymerase chain reaction, and the protein expressions of AQP1 and AQP2 in kidney were detected by immunohistochemistry. Enzyme-linked immune sorbent assay was used to detect the OVA-specific endothelium-1 (ET-1), antidiuretic hormone (ADH), atrial natriuretic peptide (ANP), prostaglandin E2 (PGE2), and angiotensin II (Ang II) levels in serum, lung and kidney tissues, respectively. The nitric oxide (NO) contents in serum, lung, and kidney tissues were tested by chemical method, respectively. Compared with the control group, the serum IgE level in model group increased (P<0.01). Following the pathologic changes in lung tissue, no significant change in kidney tissue was observed among 3 groups. Compared with the control group, the mice in the model group showed elevated airway resistance during inhalation phase, higher mRNA and protein expression levels on AQP1 and AQP2 in kidney tissue and higher ET-1 levels in serum, lung and kidney tissues, ADH and ANP in lung and serum, PGE2 in kidney, Ang II in lung and kidney tissues (P<0.05 or P<0.01), but decreased in 5-h urinary output as well as NO and PGE2 contents in serum and lung tissues (P<0.05 or P<0.01). Compared with the model group, the mice in the SAD group showed a weakened airway resistance in inspiratory phase, lower mRNA and protein expressions of AQP1 and AQP2 in kidney tissues, lower levels of ET-1, ADH, ANP in serum as well as ET-1, ANP, Ang II levels in kidney tissues (P<0.05 or P<0.01), whereas 5-h urinary output, NO content in kidney, ADH, ANP and PGE2 levels in lung and Ang II in serum increased (P<0.05 or P<0.01). San-Ao Decoction can regulate the urine volume through regulating AQP1 and AQP2 expression, and the expression of these in the kidneys might be regulated by ET-1, NO and Ang II.

Bronchial Allergen Challenge of Patients with Atopic Asthma Triggers an Alarmin (IL-33, TSLP, and IL-25) Response in the Airways Epithelium and Submucosa

The alarmin cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) play a critical role in asthma pathogenesis by inducing mucosal Th2-type cytokine production. Although environmental exposure to aeroallergens has been proposed as an alarmin trigger in asthma, there has been no systematic parallel study of the effects of allergen exposure on the expression of these cytokines in the airways of human asthmatics. Using single and sequential double immunohistochemistry, we evaluated the numbers and phenotypes of IL-25-, IL-33-, and TSLP-immunoreactive cells in sections of bronchial biopsies from mild atopic asthmatics (n = 16) before and 24 h after allergen inhalational challenge. Allergen challenge highly increased expression of baseline immunoreactivity for IL-25, IL-33, and TSLP, both in the bronchial epithelium and submucosa (p < 0.001), to a degree that correlated with the extent of the late phase of airway obstruction. Aside from epithelial cells, the principal source of immunoreactivity for all three alarmins, TSLP, and IL-33 immunoreactivity colocalized principally with endothelial cells and mast cells, neutrophils, and fibroblasts, whereas IL-25 immunoreactivity colocalized principally with eosinophils as well as endothelial cells, mast cells, and fibroblasts. The data implicate that allergen challenge directly increases airway alarmin expression in atopic asthmatics to a degree correlating with increase late-phase airway obstruction, affirming these molecules as potential molecular targets for the inhibition of allergen-induced airway inflammation and obstruction.

Hypersensitivity pneumonitis in fish processing workers diagnosed by inhalation challenge.

Hypersensitivity pneumonitis may be caused by occupational exposure in the fish processing industry http://ow.ly/GbEf30lFnyk

Cleaning agent occupational asthma in the West Midlands, UK: 2000–16

Cleaning agents are now a common cause of occupational asthma (OA) worldwide. Irritant airway and sensitization mechanisms are implicated for a variety of old and new agents. To describe the exposures responsible for cleaning agent OA diagnosed within a UK specialist occupational lung disease service between 2000 and 2016. The Birmingham NHS Occupational Lung Disease Service clinical database was searched for cases of OA caused by cleaning agents, and data were gathered on age, gender, atopic status, smoking history, symptom onset, diagnostic investigations (including Occupational Asthma SYStem analysis of workplace serial peak expiratory flow measurements and specific inhalational challenge), proposed mechanism, industry, occupation and causative agent. Eighty patients with cleaning agent OA (77% female, 76% arising de novo) were identified. The median annual number of cases was 4 (interquartile range = 2-7). The commonest cleaning agents causing OA were chloramines (31%), glutaraldehyde (26%) and quaternary ammonium compounds (11%) and frequently implicated industries were healthcare (55%), education (18%) and leisure (8%). Certain cleaning agents in common usage, such as chlorine-releasing agents, quaternary ammonium compounds and aldehydes, are associated with sensitization and asthma. Their use alters over time, and this is particularly evident in UK healthcare where cleaning and decontamination practice and policy have changed. Vigilance for OA in workplaces such as hospitals, nursing homes, leisure centres and swimming pools, where these cleaning agents are regularly used, is therefore essential.

Occupational Asthma From Epoxy Compounds

Two-component epoxy resin systems (ERSs) composed of epoxy resin and polyamine hardeners are extensively used in industrial and construction coating. Triglycidyl isocyanurate (TGIC) is another type of epoxy derivative, mostly encountered in polyester powder paints. Epoxy compounds are well-known skin sensitizers, but their respiratory-sensitizing potential is largely unknown. To report patients examined for occupational asthma (OA) from epoxy compounds. We retrospectively reviewed patient files of cases tested with a placebo-controlled specific inhalation challenge (SIC) according to their workplace exposure-either by mixing epoxy resin and the polyamine hardener of a 2-component paint or by dusting or heating TGIC-containing powder paint. The data were collected from the Finnish Institute of Occupational Health, Helsinki, Finland, and at Fundación Jiménez Díaz Hospital, Madrid, Spain, during 1997 to 2018. We also measured airborne polyamine and solvent vapors at the workplace and during SIC with ERSs. Altogether 113 patients with work-related asthma symptoms underwent SIC with ERSs. Fifteen cases (13%) had positive SIC reactions confirming OA; in 12 cases reactions were late-type, in 1 case early, and in 2 cases combined. The median duration of exposure for patients with OA was 10 years; 2 of them (13%) had a diagnosis of allergic contact dermatitis from ERS compounds. In addition, 3 cases had a positive SIC reaction to TGIC. The airborne polyamine levels measured were low. ERSs and TGIC can cause sensitizer-induced OA in some exposed workers. Respiratory exposure to ERSs is difficult to demonstrate using air measurements.

Revising the Criteria for Occupational Mould-Related Disease: Arguments, Misconceptions, and Facts

Occupational exposure to indoor air moulds and the consequent development of dampness and mould hypersensitivity syndrome (DMHS) may cause lung damage; in most cases, this is not allergic asthma mediated by specific immunoglobulin E-class antibodies. Instead, it is often a hypersensitivity pneumonitis or bronchopneumonitis. In Finland, the current diagnostic criteria for occupational DMHS have been adapted from knowledge of immunoglobulin E-mediated asthma; however, the safety of the methods used in occupational medicine have been insufficiently addressed in the literature. Accordingly, the aim of this paper is to raise awareness about the safety of current methods: specific inhalation challenge, workplace peak expiratory flow monitoring, and histamine provocation tests, by illustrating four cases. The medical records of these four cases with documented occupational DMHS were reviewed. The presented evidence suggests that the methods applied to study the occupational nature of lung damage are not suitable and the current ethics are questionable. The authors claim that, in particular, serial inhalation challenge with extracts from moulds, workplace serial peak expiratory flow leading to continuous exposure to mycotoxins, and histamine provocation tests may irreversibly damage the health of DMHS patients. Therefore, there is a prompt need to revise current practice guidelines to assess occupational DMHS. The guidelines should not be based on old dogmas, nor should they be influenced by insurance considerations. Instead, they should be based solely on medical evidence and, crucially, they should be safe for the patient and, therefore, should be implemented with caution.

IL-22 promotes allergic airway inflammation in epicutaneously sensitized mice

Serum IL-22 levels are increased in patients with atopic dermatitis, which commonly precedes asthma in the atopic march. Epicutaneous sensitization in mice results in TH2-dominated skin inflammation that mimics atopic dermatitis and sensitizes the airways for antigen challenge-induced allergic inflammation characterized by the presence of both eosinophils and neutrophils. Epicutaneous sensitization results in increased serum levels of IL-22. We sought to determine the role of IL-22 in antigen-driven airway allergic inflammation after inhalation challenge in epicutaneously sensitized mice. Wild-type (WT) and Il22-/- mice were sensitized epicutaneously or immunized intraperitoneally with ovalbumin (OVA) and challenged intranasally with antigen. OVA T-cell receptor-specific T cells were TH22 polarized invitro. Airway inflammation, mRNA levels in the lungs, and airway hyperresponsiveness (AHR) were examined. Epicutaneous sensitization preferentially elicited an IL-22 response compared with intraperitoneal immunization. Intranasal challenge of mice epicutaneously sensitized with OVA elicited in the lungs Il22 mRNA expression, IL-22 production, and accumulation of CD3+CD4+IL-22+ T cells that coexpressed IL-17A and TNF-α. Epicutaneously sensitized Il22-/- mice exhibited diminished eosinophil and neutrophil airway infiltration and decreased AHR after intranasal OVA challenge. Production of IL-13, IL-17A, and TNF-α was normal, but IFN-γ production was increased in lung cells from airway-challenged and epicutaneously sensitized Il22-/- mice. Intranasal instillation of IFN-γ-neutralizing antibody partially reversed the defect in eosinophil recruitment. WT recipients of TH22-polarized WT, but not IL-22-deficient, T-cell receptor OVA-specific T cells, which secrete both IL-17A and TNF-α, had neutrophil-dominated airway inflammation and AHR on intranasal OVA challenge. Intranasal instillation of IL-22 with TNF-α, but not IL-17A, elicited neutrophil-dominated airway inflammation and AHR in WT mice, suggesting that loss of IL-22 synergy with TNF-α contributed to defective recruitment of neutrophils into the airways of Il22-/- mice. TNF-α, but not IL-22, blockade at the time of antigen inhalation challenge inhibited airway inflammation in epicutaneously sensitized mice. Epicutaneous sensitization promotes generation of antigen-specific IL-22-producing T cells that promote airway inflammation and AHR after antigen challenge, suggesting that IL-22 plays an important role in the atopic march.

Inhalation of electronic cigarette aerosol induces reflex bronchoconstriction by activation of vagal bronchopulmonary C-fibers.

The electronic cigarette (e-cig) has been suggested as a safer alternative to tobacco cigarettes. However, the health effects of e-cigs on the airways have not been fully investigated. Nicotine, the primary chemical constituent of the e-cig aerosol, has been shown to stimulate vagal bronchopulmonary C-fiber sensory nerves, which upon activation can elicit vigorous pulmonary defense reflexes, including airway constriction. In this study, we investigated the bronchomotor response to e-cig inhalation challenge in anesthetized guinea pigs and the mechanisms involved in regulating these responses. Our results showed that delivery of a single puff of e-cig aerosol into the lung triggered immediately a transient bronchoconstriction that sustained for >2 min. The increase in airway resistance was almost completely abolished by a pretreatment with either intravenous injection of atropine or inhalation of aerosolized lidocaine, suggesting that the bronchoconstriction was elicited by cholinergic reflex mechanism and stimulation of airway sensory nerves was probably involved. Indeed, electrophysiological recording further confirmed that inhalation of e-cig aerosol exerted a pronounced stimulatory effect on vagal bronchopulmonary C-fibers. These effects on airway resistance and bronchopulmonary C-fiber activity were absent when the e-cig aerosol containing zero nicotine was inhaled, indicating a critical role of nicotine. Furthermore, a pretreatment with nicotinic acetylcholine receptor antagonists by inhalation completely prevented the airway constriction evoked by e-cig aerosol inhalation. In conclusion, inhalation of a single puff of e-cig aerosol caused a transient bronchoconstriction that was mediated through cholinergic reflex and triggered by a stimulatory effect of nicotine on vagal bronchopulmonary C-fiber afferents.

An increase of fractional exhaled nitric oxide after specific inhalation challenge is highly predictive of occupational asthma.

An increase of fractional exhaled nitric oxide (FeNO) has been described after specific inhalation challenges (SICs) with occupational allergens, but the clinical role of FeNO measurements before and after SIC is unknown. It was the aim of this study to assess the diagnostic accuracy of FeNO measurements before and after SIC in subjects with suspected occupational asthma (OA). One hundred forty-eight patients with suspected OA were examined by SIC with various occupational allergens. Subjects were assigned to pulmonary responders, nonresponders or doubtful by standard lung function criteria. FeNO was measured before SIC (baseline) and 24h afterwards. Subjects with negative or doubtful SIC but increase of FeNO were evaluated individually by an overall expert rating. Effect modifiers of FeNO increases were assessed by regression analyses. Thirty-one patients (21%) were classified as pulmonary responders, 105 (71%) as nonresponders and 12 (8%) as doubtful. With the pulmonary responder status as gold standardan increase of FeNO ≥ 13ppb showed a specificity of 0.9 and a sensitivity of 0.5. Seventeen subjects with negative or doubtful responder status showed such an increase of FeNO, among them 13 subjects with definitive or probable OA after expert rating. Regression analyses revealed no significant modifiers for the FeNO increase. An increase of FeNO after SIC is highly predictive of OA and should be regarded as an additional criterion for the interpretation of SIC with occupational agents.

Hopkins syndrome following the first episode of bronchial asthma associated with enterovirus D68: a case report

BackgroundHopkins syndrome (HS) is a rare disorder presenting with acute flaccid paralysis of the limbs following an asthma attack. Neurologists encounter a diagnostic challenge if patients without a history of bronchial asthma develop neurologic features mimicking HS following acute respiratory distress. We report a case of HS occurring after a first episode of bronchial asthma associated with enterovirus D68 infection.Case presentationA 5-year-old girl developed acute respiratory distress. On the fourth hospital day, both her legs became paralyzed except for slight muscle contraction in the right lower limb. Tendon reflexes in the lower limbs were diminished and there was a positive Babinski sign on the right. Sensation was normal in all modalities, and there was no uro-rectal disturbance. Spinal magnetic resonance imaging identified T2-hyperintense lesions with spinal cord edema, mainly involving the bilateral T11 to L1 anterior horns, with left side dominance extending to the left posterior horn. The neurological and neuro-radiological findings of our case were suggestive of HS; however, she had no history of bronchial asthma. An acetylcholine inhalation challenge eventually proved the presence of reversible airway hyper-responsiveness, allowing us to diagnose HS. We identified enterovirus D68 in the patient’s intratracheal aspirates using a sensitive polymerase chain reaction assay. Intravenous immunoglobulin administrations at 2 g/kg2 for 5 consecutive days were repeated every month up to four times. After these treatments, the muscle strength of her right lower limb slightly improved while her left lower leg remained completely paralyzed.ConclusionThis case emphasizes the importance of provocation tests to reveal the presence of airway hyper-responsiveness when a child shows neurological signs mimicking HS following acute respiratory distress. Furthermore, the present case suggests a possible link between HS and acute flaccid paralysis following lower respiratory tract infection by enterovirus D68.

Do laboratory challenge tests for occupational asthma represent what happens in the workplace?

Specific inhalation challenge (SIC) is the diagnostic reference standard for occupational asthma; however, a positive test cannot be considered truly significant unless it can be reproduced by usual work exposures. We have compared the timing and responses during SIC in hospital to Oasys analysis of serial peak expiratory flow (PEF) during usual work exposures.All workers with a positive SIC to occupational agents between 2006 and 2015 were asked to measure PEF every 2 h from waking to sleeping for 4 weeks during usual occupational exposures. Responses were compared between the laboratory challenge and the real-world exposures at work.All 53 workers with positive SIC were included. 49 out of 53 had records suitable for Oasys analysis, 14 required more than one attempt and all confirmed occupational work-related changes in PEF. Immediate SIC reactors and deterioration within the first 2 h of starting work were significantly correlated with early recovery, and late SIC reactors and a delayed start to workplace deterioration were significantly correlated with delayed recovery. Dual SIC reactions had features of immediate or late SIC reactions at work rather than dual reactions.The concordance of timings of reactions during SIC and at work provides further validation for the clinical significance of each test.

Methacholine challenge testing: comparative pharmacology.

Standardization of the methacholine inhalation challenge, the most common direct bronchoprovocation test, is important. One aspect of standardization is the appropriate washout period for pharmacologic agents which affect the response. This review summarizes the available data on pharmacologic inhibition of the methacholine response. Specific (anti-muscarinic) agents demonstrate marked bronchoprotection (up to 7 days for the long-acting drugs) which lasts longer than the duration of bronchodilation. The functional antagonist (beta 2 agonist class of medications) shows marked, but less, bronchoprotection which is relatively short lived and is similar to the duration of bronchodilator efficacy. Tolerance develops quickly, especially to the long-acting agents. Single doses of controller medications, such as inhaled corticosteroids (ICS) and leukotriene receptor antagonists, have no effect on the methacholine test, while regular use, at least for ICS, has a modest protective effect whose duration is uncertain and likely variable. Theophylline has a small effect and H1 blockers (all generations) have a negligible effect.

IL-33 and Its Receptor ST2 after Inhaled Allergen Challenge in Allergic Asthmatics

Background: Previous murine models have demonstrated interleukin (IL)-33 to be an important mediator of type-2 inflammation and to promote airway hyperresponsiveness in allergic asthma. A number of inflammatory cells produce IL-33 and eosinophils express ST2 mRNA. The relationship between IL-33 and eosinophils in allergic asthma, however, remains unclear. Objective: The aim of this work was to evaluate in vitro the effect of allergen inhalation on IL-33 levels and expression of its receptor (ST2L) on eosinophils in allergic asthmatics, and the effect of IL-33 stimulation on eosinophil activity. Methods: Plasma and sputum IL-33, soluble ST2 (sST2) levels, and ST2L expression on eosinophils were measured in 10 healthy controls and 10 allergic asthmatics. Asthmatics underwent allergen and diluent inhalation challenges. Blood and sputum samples were collected to measure IL-33, sST2, and ST2L eosinophil expression before and 24 h after allergen inhalation. Purified blood eosinophils from allergic asthmatics were incubated overnight with IL-33 to assess ST2 and intracellular IL-5 expression. Results: Baseline levels of IL-33 in sputum and sST2 in plasma and sputum were similar in allergic asthmatics compared to healthy controls. In addition, there was no difference in blood or sputum eosinophil ST2L expression in healthy controls versus allergic asthmatics. Eosinophil ST2L expression was significantly increased 24 h postallergen inhalation in allergic asthmatics. In vitro stimulation of human eosinophils with IL-33 and LPS significantly increased eosinophil ST2L expression and IL-33 stimulation increased intracellular IL-5 expression, which was attenuated by treatment with sST2 and ST2 blockade. Conclusion and Clinical Relevance: In mild asthmatics, there was a significant upregulation of ST2 surface expression on eosinophils from blood and sputum following allergen inhalation challenge. In vitro, IL-33 stimulation of eosinophils increases both ST2 membrane expression and IL-5 production. These results support a role for IL-33 in causing allergen-induced eosinophilia. Blockade of IL-33 and ST2 signaling may present a novel therapeutic avenue for asthma treatment.

Cough response to sulfur dioxide inhalation challenge is enhanced by tumor necrosis factor alpha: a primary role of vagal bronchopulmonary C‐fibers

Tumor necrosis factor alpha (TNFα), a pro‐inflammatory cytokine, plays a significant role in the pathogenesis of asthma. We recently reported that TNFα pretreatment elevated the sensitivities of vagal bronchopulmonary C‐fibers and silent rapidly adapting rectors (RARs) to capsaicin (Front. Physiol. 2017). In this study, we investigated the effect of TNFα on cough response to sulfur dioxide (SO2), a common irritant gas, and the relative contributions of these vagal afferents. Our results showed: 1) Inhalation of SO2 (300 and 600 ppm; 8 min each) consistently elicited coughs in a concentration‐dependent manner in awake mice moving freely in a recording chamber; coughs were recorded via telemetry sensors implanted in the intrapleural space. The cough frequencies during and immediately after the SO2 inhalation challenges increased markedly in the same animals after TNFα (10 μg/ml; 0.03 ml) was administered into the lung by intratracheal instillation, and this increase in cough sensitivity sustained for &gt;7 days after the TNFα pretreatment. In contrast, the cough response to SO2 inhalation challenges did not change after pretreatment with vehicle (0.03 ml of PBS) in a matching group of control mice. 2) In single‐fiber recording experiments in anesthetized mice, the same SO2 inhalation challenges (for 8 min) evoked a pronounced stimulatory effect on C‐fiber afferents, reaching a peak in 1–4 min. The increased fiber activity was concentration dependent and lingered for several more minutes after the termination of SO2 challenge. This stimulatory effect of SO2 was significantly elevated in the TNFα‐treated mice. 3) The same SO2 inhalation challenges, either 300 or 600 ppm, did not activate any of the silent RARs in vehicle‐treated mice, and only 600 ppm SO2 caused a very weak stimulation in 2 out of 7 of these silent RARs in TNFα‐treated mice. 4) Inhalation of SO2 (300 or 600 ppm) consistently induced an inhibitory effect on both slowly adapting receptors and phasic RARs; these afferents ceased to discharge completely in 1–5 min after the onset of SO2 (600 ppm) inhalation challenge, and a majority of them slowly returned to controls after resuming air breathing for &gt;1 hr. No detectable difference in this inhibitory effect was found between TNFα‐ and vehicle‐treated mice. In conclusion, the cough response to SO2 inhalation challenge is enhanced by the TNFα pretreatment in wake mice, and an increase in the bronchopulmonary C‐fiber sensitivity to SO2 is primarily responsible.Support or Funding InformationNIH grant AI123832This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.