Mechanisms of airway hyperresponsiveness in asthma

The Expression of Semaphorin3E in Vagal Ganglion and Lung Tissue Is Related to Airway Hyperresponsiveness in Murine Asthma Model

Objective

Semaphorin3E (Sema3E) mediates reorganization of the actin cytoskeleton, and plays an important role in ensuring the specificity of synapse formation and angiogenesis. However, the role of Sema3E in allergic asthma (AS) and eosinophilic bronchitis (EB) is still elusive. This study aimed to investigate the relationship between Sema3E in vagal ganglion and lung tissue, airway reactivity, and eosinophilic inflammation.

Methods

The frequency of coughs and airway reactivity as well as the airway inflammation were observed in ovalbumin- (OVA-) induced AS and EB mouse models. The expression of Sema3E was examined in the vagal ganglion and lung tissues by immunofluorescence staining and western blotting analyses. In the Sema3E treatment protocol, exogenous Sema3E was administrated intranasally before challenge in AS model to study the effect of Sema3E on airway hyperresponsiveness, airway inflammation, mucus production, and collagen deposition.

Results

The similar higher frequency of coughs and airway eosinophilic inflammation could be seen in AS and EB groups compared with nasal saline (NS) and dexamethasone (DXM) groups. The absence of the airway hyperresponsiveness was observed in EB and DXM group, while AS group showed increase in airway reactivity to methacholine. The expression of Sema3E in vagal ganglion and lung tissue was remarkably decreased in AS and DXM group compared with EB group. Sema3E-treated asthma mice displayed ameliorated airway hyperresponsiveness, mucus production, and collagen deposition.

Conclusion

Sema3E in lungs and vagal ganglia is related to eosinophilic inflammation and has a protective effect on OVA-induced AHR in asthma.

The contribution of reticular basement membrane proteins to basal airway epithelial attachment, spreading and barrier formation: implications for airway remodeling in asthma

Rationale

In the healthy lung, the pseudostratified conducting airway epithelium is anchored to the reticular basement membrane (RBM) via hemidesmosome junction complexes formed between basal cells and the extracellular matrix (ECM). The RBM within the healthy lung is composed of the ECM proteins laminin and collagen-IV. In patients with asthma, the RBM is remodeled with collagen-I, -III and fibronectin deposition. The goal of this study was to assess the effect of RBM ECM proteins on basal airway epithelial cell attachment, spreading and barrier formation using real-time electrical cell-substrate impedance sensing (ECIS).

Methods

ECIS 8-well arrays were coated with 50 μg/mL of fibronectin, collagen-I, collagen-III, collagen-IV, or laminin and compared to bovine serum albumin (BSA) or uncoated controls. The airway epithelial cell line (1HAEo-) was seeded 40, 50, 60, and 70 k cells/well and continuously monitored over 70 h to assess cell attachment, spreading and barrier formation using high (64 k Hz) and low (500 Hz) frequency resistance and capacitance. Data were analyzed using a one-phase decay model from which half-life (time cells cover half of the electrode area) and rate-constant (cell-spreading rate/h) were determined and a generalized additive mixed effect model (GAMM) was used to assess ECM proteins over the entire experiment.

Results

High-frequency (64 kHz) capacitance measures demonstrated the half-life for 1HAEo-cells to attach was fastest when grown on fibronectin (6.5 h), followed by collagen-I (7.2 h) and collagen-III (8.1 h), compared to collagen-IV (11.3 h), then laminin (13.2 h) compared to BSA (12.4 h) and uncoated (13.9 h) controls. High-frequency (64 kHz) resistance measures demonstrated that the rate of 1HAEo- cell spreading was significantly faster on fibronectin and collagen-I compared to collagen-III, collagen-IV, laminin, BSA and the uncoated control. Low-frequency (500 Hz) resistance measures demonstrated that 1HAEo-cells formed a functional barrier fastest when grown on fibronectin and collagen-I, compared to the other ECM conditions. Lastly, the distance of 1HAEo-cells from the ECM substrates was the smallest when grown on fibronectin reflecting high cell-matrix adhesion.

Conclusion

Airway epithelial cells attach, spread and form a barrier fastest on fibronectin, and collagen-I and these reticular basement membrane ECM proteins may play a protective role in preserving the epithelial barrier during airway remodeling in asthma.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

Clinical and Inflammatory Characteristics of the Chinese APAC Cough Variant Asthma Cohort

Background

The AtyPical Asthma in China (APAC) cohort is a multi-center prospective, observational cohort set-up to investigate the clinical, pathophysiological features, prognosis, and mechanisms of cough variant asthma (CVA).

Objectives

To present the characteristics of newly physician-diagnosed adults with CVA (n = 328) compared to mild-moderate classic asthma (CA, n = 206).

Methods and Main Results

CVA subjects showed a higher proportion of female (67.1 vs. 55.3%, P = 0.0084), abnormal laryngopharyngeal sensations (71 vs. 51%, p < 0.0001) than CA, but presented with near normal spirometry and higher methacholine PD20-FEV1 values [4.2 (1, 8.6) vs. 0.8 (0.4, 4.7), P < 0.0001]. Lower fractional exhaled nitric oxide (FENO) levels [38.5 (19.8, 72.5) vs. 53. (28.5, 92.2), P = 0.0019], blood eosinophil counts [0.2 (0.1, 0.4) vs. 0.3 (0.2, 0.5), P = 0.0014], and sputum eosinophils [2.3 (0.3, 8.0) vs. 12.2 (2, 34.5), p < 0.0001] were found in CVA. Despite lower total serum IgE levels in CVA, there was similar proportion of atopy in both groups. The prevalence of cough in CA was 86.4%, while CVA reported more severe cough on Visual Analog Scale, Cough Evaluation Test, and Leicester Cough Questionnaire, similar anxiety and depression scores but better asthma control scores as reflected by Asthma Control Test compared to CA. No correlation was found between cough assessment outcomes and sputum eosinophil count, blood eosinophil count, FENO, spirometry variables, or PD20-FEV1.

Conclusion

Cough variant asthma is distinctive from classic asthma in regard to clinical features, lung function, and airway inflammation. Quality of life is badly impaired as well in spite of better asthma control scores.

Beneficial effects of naringenin and morin on interleukin-5 and reactive oxygen species production in BALB/c mice with ovalbumin-induced asthma

We investigated the effects of naringenin and morin on IL-5 and ROS production in PMA+ionomycin-treated EL-4 cells with the corroboration of their antioxidant and anti-inflammatory properties using an asthma-induced mouse model. The EL-4 cell line was used to study the outcomes of naringenin or morin, followed by cell viability studies. Western blot analysis and ELISA test were used to determine Th2 mediated cytokines. In vivo studies were carried out on BALB/c mice to induce allergic asthma using ovalbumin administered intraperitoneally. Intracellular ROS was determined using 2’,7’-dichlorodihydrofluorescein diacetate, followed by serum enzymatic (AST and ALT) estimations and inflammatory cell count in the bronchoalveolar lavage fluid (BALF) and lung tissues. Histopathological studies were conducted to examine lung tissue-stained architecture. Our findings suggested that naringenin and morin significantly suppressed IL-5 and ROS production via various pathways. Interestingly, by reducing NFAT activity, naringenin and morin stimulated HO-1 expression, thereby suppressing IL-5 secretion due to regulating the transcription factor Nrf2 via P13/Akt or ERK/JNK signalling pathways in EL-4 cells, demonstrating the involvement of HO-1 expression in inhibiting asthmatic inflammation. The increased inflammatory cells in the BALF were substantially decreased by both naringenin and morin, followed by inhibition in the elevated Th-2 cytokines levels. The TNF-α protein levels in an allergic asthma mouse model were significantly reduced by suppressing Akt phosphorylation and eosinophil formation. Recent findings confirmed that naringenin and morin possess the potential to control asthma-related immune responses through antioxidant and anti-inflammatory properties, indicating potential therapeutic agents or functional foods.

Eosinophils in Asthma Models to House Dust Mite for Drug Development

Murine models of asthma are developed to better understand the mechanisms of asthma including eosinophil recruitment in the airways with the aim of evaluating new therapeutic strategies. They are intended to model the typical features of human disease, in particular airway inflammation, hyperresponsiveness (AHR), and remodeling. The phenotype of inflammatory cells recovered from the bronchoalveolar lavage fluid (BAL) is studied with innovative flow cytometry techniques while airway obstruction is measured using the forced oscillation technique, and airway responsiveness approached by barometric plethysmography in awake and unconstrained animals. We here describe models of asthma of house dust mite (HDM) as a clinically relevant allergen: a short study design (8 days) model of hypereosinophilic asthma and a chronic (31 days) asthma model, both suitable to evaluate the potential of new drug candidates to prevent allergic asthma.

Borneol inhibits CD4 + T cells proliferation by down-regulating miR-26a and miR-142-3p to attenuate asthma

BACKGROUND

Asthma is a chronic airway inflammatory disease caused by a variety of cytokines and signaling pathways closely related to immunoregulation. Corticosteroids are the most widely used drug in the asthma treatment. However, the use of corticosteroids could cause topical side effects. So, it's important to find new drugs for asthma treatment. Our study aims to explore the pharmacological effect of borneol on asthma and its underlying mechanism.

METHODS

We constructed the OVA-induced asthma model to investigate the effect of borneol on asthma in mice. HE and PAS staining was used to detect the effect of borneol on pathological change of mice with asthma. Inflammatory cytokines were measured by ELISA. qRT-PCR was used to explore the effect of borneol on microRNAs expression. Cell proliferation of CD4 + T cells was detected by CCK-8 assay and flow cytometry. Western blot was used to detect pten expression and Akt activation.

RESULTS

We found that borneol significantly alleviated asthma progression in mice. Borneol inhibited CD4 + T cells infiltration in vivo and proliferation in vitro by downregulating miR-26a and miR-142-3p. miR-26a and miR-142-3p promoted CD4 + T cells proliferation in vitro through targeting Pten. Overexpression of miR-26a and miR-142-3p abolished the effect of borneol in vivo.

CONCLUSION

In a word, these findings suggested that borneol attenuated asthma in mice by decreasing the CD4 + T cells infiltration. The molecular mechanism of borneol was dependent on the downregulation of miR-26a and miR-142-3p to upregulate the Pten expression.

The AKT inhibitor MK2206 suppresses airway inflammation and the pro‑remodeling pathway in a TDI‑induced asthma mouse model

The cellular and molecular mechanisms via which MK2206, an AKT inhibitor, prevents the activation of AKT in toluene diisocyanate (TDI)‑induced asthma remain unclear. Thus, the present study aimed to evaluate the potential effects of MK2206 on airway AKT activation, inflammation and remodeling in a TDI‑induced mouse model of asthma. A total of 24 BALB/c mice were selected and randomly divided into untreated (AOO), asthma (TDI), MK2206 (TDI + MK2206), and dexamethasone (TDI + DEX) groups. Phosphorylated AKT (p‑AKT), total AKT, airway remodeling indices, α‑smooth muscle actin (α‑SMA) and collagen I levels in pulmonary tissue were measured using western blotting. Airway inflammation factors, including interleukin (IL)‑4, ‑5, ‑6, and ‑13 in bronchoalveolar lavage fluid (BALF) and IgE in serum, were determined using ELISA. Additionally, the airway hyperresponsiveness (AHR) and pulmonary pathology of all groups were evaluated. The results of the present study demonstrated that p‑AKT levels in lung protein lysate were upregulated, and neutrophil, eosinophil and lymphocyte counts were increased in the lungs obtained from the asthma group compared with the AOO group. Both MK2206 and DEX treatment in TDI‑induced mice resulted not only in the attenuation of AKT phosphorylation, but also reductions in neutrophil, eosinophil and lymphocyte counts in the lungs of mice in the asthma group. Consistently, increases in the levels of the inflammatory cytokines IL‑4, ‑5, ‑6 and ‑13 analyzed in BALF, and serum IgE in the TDI group were demonstrated to be attenuated in the TDI + MK2206 and TDI + DEX groups. Furthermore, α‑SMA and AHR were significantly attenuated in the TDI + MK2206 group compared with the TDI group. These results revealed that MK2206 not only inhibited AKT activation, but also served a role in downregulating airway inflammation and airway remodeling in chemical‑induced asthma. Therefore, the findings of the present study may provide important insight into further combination therapy.

Inhalations with Brine Solution from the 'Wieliczka' Salt Mine Diminish Airway Hyperreactivity and Inflammation in a Murine Model of Non-Atopic Asthma

Inhalations with brine solutions are old but underestimated add-ons to pharmacological treatments of inflammatory lung diseases. Although widely used, not all features underlying their action on the respiratory system have been explored. The aim of the present study was to elucidate the mechanism of the beneficial action of inhalations of brine solution from the 'Wieliczka' Salt Mine, a Polish health resort, in a murine model of non-atopic asthma. Asthma was induced in BALB/c mice by skin sensitization with dinitrofluorobenzene followed by an intratracheal challenge of cognate hapten. All animals underwent 12 inhalation sessions with brine solution, pure water or physiological saline. Control mice were not inhaled. We found that brine inhalations reduced, as compared to non-inhaled mice, the typical asthma-related symptoms, like airway hyperreactivity (AHR), the infiltration of pro-inflammatory cells into the bronchial tree, and the inflammation of the airways at the level of pro-inflammatory cytokines IL-1α, IL-1β and IL-6. The level of the anti-inflammatory IL-10 was elevated in brine-inhaled mice. Inhalations with pure water increased AHR, whereas saline had no influence, either on AHR or cytokine concentrations. These observations indicate that inhalations with a brine solution from the 'Wieliczka' Salt Mine diminish the asthma-related symptoms, mostly by reducing the inflammatory status and by decreasing AHR.

Older age and obesity are associated with increased airway closure in response to methacholine in patients with asthma

BACKGROUND AND OBJECTIVE

The reduction of forced expiratory volume in 1 s (FEV₁ ) in response to methacholine challenge in asthma may reflect two components: airway narrowing, assessed by the change in FEV₁ /forced vital capacity (FVC), and airway closure, assessed by the change in FVC. The purpose of this study was to determine the degree and determinants of airway closure in response to methacholine in a large group of asthmatic patients participating in studies conducted by the American Lung Association-Airways Clinical Research Centers (ALA-ACRC).

METHODS

We used the methacholine challenge data from participants in five studies of the ALA-ACRC to determine the closing index, defined as the contribution of airway closure to the decrease in FEV₁ , and calculated as %ΔFVC/%ΔFEV₁ .

RESULTS

There were a total of 936 participants with asthma, among whom the median closing index was 0.67 relative to that of a published healthy population of 0.54. A higher closing index was associated with increased age (10-year increments) (0.04, 95% CI = 0.02, 0.05, P < 0.005) and obesity (0.07, 95% CI = 0.03, 0.10, P < 0.001). There was no association between the closing index and asthma control.

CONCLUSION

Our findings confirm that airway closure in response to methacholine occurs in a large, diverse population of asthmatic participants, and that increased airway closure is associated with older age and obesity. These findings suggest that therapies targeting airway closure may be important in patients with a high closing index.

Petiveria alliacea Suppresses Airway Inflammation and Allergen-Specific Th2 Responses in Ovalbumin-Sensitized Murine Model of Asthma

OBJECTIVE

To examine the effect of metanol extract of Petiveria alliacea (PM) on airway inflflammation in a murine model of chronic asthma.

METHODS

Two-month-old male BALB/c mice (n=6-8/group) were sensitized on days 0 and 14 by intraperitoneal injection of 20 μg ovalbumin (OVA). On day 25, the mice received an airway challenge with OVA (3%, w/v, in phosphate buffered saline). PM was administered orally by oral gavage to mice at doses of 100, 200 and 400 mg/kg body weight once daily from days 18 to 23. Control mice were orally administered phosphate buffered saline (PBS) to induce a model of asthma. At the end of the test, respiratory reactivity was assayed, the total cell number, interleukin-4 (IL-4), IL-5, IL-13, tumor necrosis factor-alpha (TNF-α) and reactive oxygen species (ROS) in the bronchoalveolar lavage fluid (BALF) were determined and the levels of serum IgE, intercellular cell adhesion molecule 1 (ICAM-1) and eotoxin were measured. In addition, lung tissue was used to qualify the IL-4, IL-5, IL-13, TNF-α and transforming growth factor beta 1 (TGF-β1). Histologic examination was performed to observe inflammatory cellular infiltration.

RESULTS

The administration of PM in comparison with the OVA-only treated group signifificantly attenuated the infifiltration of eosinophils and other inflflammatory cells (P<0.01). Airway resistance (RI) in the OVA-only induced group was significantly higher than that of the PBS control group (P<0.01) when methacholine was added. TNF-α, IgE, TGF-β1 and cytokine levels IL-4, IL-5, IL-13 in the BALF decreased compared to control mice (P<0.01 or P<0.05). PM treatment also inhibited the production of chemokines, eotaxin and ICAM-1 in BALF (P<0.01), which improved lung function. Histopathological examination revealed that the sensitized treated PM groups had significant lower in inflammatory scores similar to dexamethasone treatments and the untreated group.

CONCLUSION

Administration of PM could inhibit airway inflammation, regulate cytokines, chemokines and enhance pulmonary conditions in allergic murine model of asthma.

Inhaled corticosteroids for bronchiectasis

BACKGROUND

Bronchiectasis is being increasingly diagnosed and recognised as an important contributor to chronic lung disease in both adults and children in high- and low-income countries. It is characterised by irreversible dilatation of airways and is generally associated with airway inflammation and chronic bacterial infection. Medical management largely aims to reduce morbidity by controlling the symptoms, reduce exacerbation frequency, improve quality of life and prevent the progression of bronchiectasis. This is an update of a review first published in 2000.

OBJECTIVES

To evaluate the efficacy and safety of inhaled corticosteroids (ICS) in children and adults with stable state bronchiectasis, specifically to assess whether the use of ICS: (1) reduces the severity and frequency of acute respiratory exacerbations; or (2) affects long-term pulmonary function decline.

SEARCH METHODS

We searched the Cochrane Register of Controlled Trials (CENTRAL), the Cochrane Airways Group Register of trials, MEDLINE and Embase databases. We ran the latest literature search in June 2017.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing ICS with a placebo or no medication. We included children and adults with clinical or radiographic evidence of bronchiectasis, but excluded people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

We reviewed search results against predetermined criteria for inclusion. In this update, two independent review authors assessed methodological quality and risk of bias in trials using established criteria and extracted data using standard pro forma. We analysed treatment as 'treatment received' and performed sensitivity analyses.

MAIN RESULTS

The review included seven studies, involving 380 adults. Of the 380 randomised participants, 348 completed the studies.Due to differences in outcomes reported among the seven studies, we could only perform limited meta-analysis for both the short-term ICS use (6 months or less) and the longer-term ICS use (> 6 months).During stable state in the short-term group (ICS for 6 months or less), based on the two studies from which data could be included, there were no significant differences from baseline values in the forced expiratory volume in the first second (FEV₁) at the end of the study (mean difference (MD) -0.09, 95% confidence interval (CI) -0.26 to 0.09) and forced vital capacity (FVC) (MD 0.01 L, 95% CI -0.16 to 0.17) in adults on ICS (compared to no ICS). Similarly, we did not find any significant difference in the average exacerbation frequency (MD 0.09, 95% CI -0.61 to 0.79) or health-related quality of life (HRQoL) total scores in adults on ICS when compared with no ICS, though data available were limited. Based on a single non-placebo controlled study from which we could not extract clinical data, there was marginal, though statistically significant improvement in sputum volume and dyspnoea scores on ICS.The single study on long-term outcomes (over 6 months) that examined lung function and other clinical outcomes, showed no significant effect of ICS on any of the outcomes. We could not draw any conclusion on adverse effects due to limited available data.Despite the authors of all seven studies stating they were double-blind, we judged one study (in the short duration ICS) as having a high risk of bias based on blinding, attrition and reporting of outcomes. The GRADE quality of evidence was low for all outcomes (due to non-placebo controlled trial, indirectness and imprecision with small numbers of participants and studies).

AUTHORS' CONCLUSIONS

This updated review indicates that there is insufficient evidence to support the routine use of ICS in adults with stable state bronchiectasis. Further, we cannot draw any conclusion for the use of ICS in adults during an acute exacerbation or in children (for any state), as there were no studies.

Solitary Cholinergic Stimulation Induces Airway Hyperreactivity and Transcription of Distinct Pro-inflammatory Pathways

Airway hyperreactivity is a hallmark feature of asthma and can be precipitated by airway insults, such as ozone exposure or viral infection. A proposed mechanism linking airway insults to airway hyperreactivity is augmented cholinergic transmission. In the current study, we tested the hypothesis that acute potentiation of cholinergic transmission is sufficient to induce airway hyperreactivity. We atomized the cholinergic agonist bethanechol to neonatal piglets and forty-eight hours later measured airway resistance. Bethanechol-treated piglets displayed increased airway resistance in response to intravenous methacholine compared to saline-treated controls. In the absence of an airway insult, we expected to find no evidence of airway inflammation; however, transcripts for several asthma-associated cytokines, including IL17A, IL1A, and IL8, were elevated in the tracheas of bethanechol-treated piglets. In the lungs, prior bethanechol treatment increased transcripts for IFNγ and its downstream target CXCL10. These findings suggest that augmented cholinergic transmission is sufficient to induce airway hyperreactivity, and raise the possibility that cholinergic-mediated regulation of pro-inflammatory pathways might contribute.

Vitamin A maintains the airway epithelium in a murine model of asthma by suppressing glucocorticoid-induced leucine zipper

BACKGROUND

The effects of glucocorticoids (GCs) on the repair of the airway epithelium in asthma are controversial, and we previously reported that the GC dexamethasone (Dex) inhibits the repair of human airway epithelial cells and that this process is mediated by glucocorticoid-induced leucine zipper (GILZ) through MAPK-ERK signaling in vitro. Vitamin A (VA) is involved in the regulation of the MAPK-ERK pathway but has not been widely supplied during asthma treatment. It is unclear whether VA attenuates the negative regulation of GILZ on the MAPK-ERK pathway and maintains airway epithelium integrity during asthma treatment.

METHODS

Female BALB/c mice were sensitized and challenged with ovalbumin (OVA) and subsequently treated with Dex, VA or intranasal inhalation of adenovirus sh-GILZ vectors. Indexes of airway epithelium integrity, including pathological alterations, pulmonary EGFR expression and airway hyperresponsiveness (AHR), were then measured. The expression of GILZ and key components of activated MAPK-ERK signals (p-Raf-1, p-MEK, and p-Erk1/2) were also detected.

RESULTS

Dex failed to relieve OVA-induced asthma airway epithelium injury, as assessed through H&E staining, EGFR expression and AHR. Moreover, in the OVA-challenged mice treated with Dex, GLIZ expression was increased, whereas the ratios of p-Raf-1/Raf-1, p-MEK/MEK and p-Erk1/2/Erk1/2 were significantly decreased. Further study indicated that GILZ expression was decreased and that the ratios of p-Raf-1/Raf-1, p-MEK/MEK and p-Erk1/2/Erk1/2 were up-regulated in the GILZ-silenced OVA-challenged mice and VA-fed OVA-challenged mice, independent of Dex treatment. The airway epithelium integrity of the OVA-challenged mice was maintained by treatment with both VA and Dex.

CONCLUSIONS

Vitamin A maintained the Dex-treated asthma airway epithelium via the down-regulation of GILZ expression and the activation MAPK-ERK signaling, and these effects might contribute to improving the effects of GC therapeutics on asthma.

CF airway smooth muscle transcriptome reveals a role for PYK2

Abnormal airway smooth muscle function can contribute to cystic fibrosis (CF) airway disease. We previously found that airway smooth muscle from newborn CF pigs had increased basal tone, an increased bronchodilator response, and abnormal calcium handling. Since CF pigs lack airway infection and inflammation at birth, these findings suggest intrinsic airway smooth muscle dysfunction in CF. In this study, we tested the hypothesis that CFTR loss in airway smooth muscle would produce a distinct set of changes in the airway smooth muscle transcriptome that we could use to develop novel therapeutic targets. Total RNA sequencing of newborn wild-type and CF airway smooth muscle revealed changes in muscle contraction-related genes, ontologies, and pathways. Using connectivity mapping, we identified several small molecules that elicit transcriptional signatures opposite of CF airway smooth muscle, including NVP-TAE684, an inhibitor of proline-rich tyrosine kinase 2 (PYK2). In CF airway smooth muscle tissue, PYK2 phosphorylation was increased and PYK2 inhibition decreased smooth muscle contraction. In vivo NVP-TAE684 treatment of wild-type mice reduced methacholine-induced airway smooth muscle contraction. These findings suggest that studies in the newborn CF pig may provide an important approach to enhance our understanding of airway smooth muscle biology and for discovery of novel airway smooth muscle therapeutics for CF and other diseases of airway hyperreactivity.

A Novel in vivo System to Test Bronchodilators

The incidence and severity of asthma continue to rise worldwide. β-agonists are the most commonly prescribed therapeutic for asthma management but have less efficacy for some subsets of asthmatic patients and there are concerns surrounding the side effects from their long-term persistent use. The demand to develop novel asthma therapeutics highlights the need for a standardized approach to effectively screen and test potential bronchoprotective compounds using relevant in vivo animal models. Here we describe a validated method of testing potential therapeutic compounds for their fast-acting efficacy during the midst of an induced bronchoconstriction in a house dust mite challenged animal model.

Epidemiology and Pulmonary Physiology of Severe Asthma

The epidemiology and physiology of severe asthma are inherently linked because of varying phenotypes and expressions of asthma throughout the population. To understand how to better treat severe asthma, we must use both population data and physiologic principles to individualize therapies among groups with similar expressions of this disease.

Regulator of G-protein signaling 2 repression exacerbates airway hyper-responsiveness and remodeling in asthma

G protein-coupled receptors (GPCRs) are important regulators of cell functions in asthma. We recently reported that regulator of G-protein signaling (RGS) 2, a selective modulator of Gq-coupled GPCRs, is a key regulator of airway hyper-responsiveness (AHR), the pathophysiologic hallmark of asthma. Because RGS2 protein levels in airway cells were significantly lower in patients with asthma compared with patients without asthma, we further investigated the potential pathological importance of RGS2 repression in asthma. The human RGS2 gene maps to chromosome 1q31. We first screened patients with asthma for RGS2 gene promoter single-nucleotide polymorphisms (SNPs) and found significant differences in the distribution of two RGS2 SNPs (A638G, rs2746071 and C395G, rs2746072) between patients with asthma and nonasthmatic subjects. These two SNPs are always associated with each other and have the same higher prevalence in patients with asthma (65%) as compared with nonasthmatic subjects (35%). Point mutations corresponding to these SNPs decrease RGS2 promoter activity by 44%. The importance of RGS2 down-regulation was then determined in an acute IL-13 mouse model of asthma. Intranasal administration of IL-13 in mice also decreased RGS2 expression in lungs by ∼50% and caused AHR. Although naive RGS2 knockout (KO) mice exhibit spontaneous AHR, acute IL-13 exposure further increased AHR in RGS2 KO mice. Loss of RGS2 also significantly enhanced IL-13-induced mouse airway remodeling, including peribronchial smooth muscle thickening and fibrosis, without effects on goblet cell hyperplasia or airway inflammation in mice. Thus, genetic variations and increased inflammatory cytokines can lead to RGS2 repression, which exacerbates AHR and airway remodeling in asthma.

Immune-modulatory effects of bu-zhong-yi-qi-tang in ovalbumin-induced murine model of allergic asthma

Background

Bu-zhong-yi-qi-tang (BZYQT), an herbal formula of traditional Chinese medicine, has been an effective regimen of allergic diseases for nearly 800 years. Our previous report has demonstrated its anti-inflammatory effects in patients with perennial allergic rhinitis, and the aim of this study is to investigate the anti-asthmatic effect of BZYQT.

Methods

Female BALB/cByJNarl mice were sensitized with normal saline (control group) or OVA. Mice sensitized by OVA were fed with distilled water (OVA group), oral 0.5 g/Kg (low-dose group) or 1 g/Kg (high-dose group) of BZYQT solution once daily on days 36-40 besides their routine diet. Airway hyper-responsiveness (AHR), eosinophil infiltration, levels of cytokines and total immunoglobulin E (IgE) in broncho-alveolar lavage fluid (BALF) were determined. The lungs and tracheas were removed, and histopathologic examination was subsequently performed.

Results

AHR was significantly reduced in both low- and high-dose BZYQT groups compared with the OVA group after inhalation of the highest dose of methacholine (50 mg/ml). The levels of eotaxin, Th2-related cytokines (IL-4, IL-5, IL-13), IgE, and eosinophil infiltration in BALF were significantly decreased in both BZYQT groups compared with the OVA group. Histopathologic examination revealed that eosinophil infiltration of the lung and trachea tissues was remarkably attenuated in both BZYQT groups.

Conclusions

Oral administration of BZYQT solution may exert anti-asthmatic effect by relieving AHR in OVA-sensitized mice, which is compatible with our clinical experience. Although detailed mechanism is to be determined, we surmise that it may be correlated with the immune-modulatory effects of inhibiting Th2 responses on the basis of our limited results.

Preliminary Investigations of the Anti-asthmatic Properties of the Aqueous Extract of Justicia pectoralis (Fresh Cut)

BACKGROUND

Justicia pectoralis (fresh cut plant), family Acantheceae, is a herb that is native to central America and the Caribbean. A crude extract prepared from the leaves of Justicia pectoralis is commonly used in Jamaican ethnotraditional medicine to reduce difficulty in breathing and suppress wheezing in asthmatic individuals.

OBJECTIVES

To investigate the anti-inflammatory and antihistamine activity of an aqueous extract of Justicia pectoralis.

METHOD

In in vivo experiments, guinea pigs were sensitized by the method of Weinrich and Undem (1987). The effect of water on the wheals was assessed in the control group, n = 4. The effect of 3.3 mg of the crude extract was noted in histamine-induced wheals over a period of three hours. The extract was injected via intraperitoneal injections. In in vitro experiments, 3.3 mg of crude sample was tested for its effectiveness against histamine-induced tracheal contraction caused by cumulative dosing of histamine.

RESULTS

The crude extract was efficacious in reducing the formation of histamine-induced wheals (p < 0.05). Results obtained from in vitro studies indicated that the crude extract (3.3 mg) caused significant reduction in tracheal smooth muscle contraction resulting from cumulative doses of histamine (p < 0.05). However, as the histamine doses increased, fresh cut extract was not able to maintain inhibition of histamine-induced tracheal smooth muscle contraction. This is an indication that the extract showed competitive reversible antagonism, possibly at histamine receptors.

CONCLUSION

A crude extract of the leaves Justicia pectoralis reduced the formation of histamine-induced wheals in sensitized guinea pigs (p < 0.05) and also reduced histamine-induced tracheal smooth muscle contractions (p < 0.05). It blocked the effect of contraction produced by histamine in the airways; this property supports folklore claims for its use as an antihistamine.

Airway response to methacholine following eucapnic voluntary hyperpnea in athletes

Aim

To evaluate the changes in airway responsiveness to methacholine inhalation test (MIT) when performed after an eucapnic voluntary hyperpnea challenge (EVH) in athletes.

Methods

Two MIT preceded (visit 1) or not (visit 2) by an EVH, were performed in 28 athletes and 24 non-athletes. Twelve athletes and 13 non-athletes had airway hyperresponsiveness (AHR) to methacholine, and 11 athletes and 11 non-athletes had AHR to EVH (EVH+).

Results

The MIT PC₂₀ post-EVH was significantly lower compared to baseline MIT PC₂₀ by 1.3±0.7 doubling-concentrations in EVH+ athletes only (p<0.0001). No significant change was observed in EVH- athletes and EVH+/EVH- non-athletes. A significant correlation between the change in MIT PC₂₀ post-EVH and EVH+/EVH- status and athlete/nonathlete status was found (Adjusted R²=0.26 and p<0.001). Three (11%) athletes and one (4%) non-athlete had a change in the diagnosis of AHR when MIT was performed consecutively to EVH.

Conclusion

The responsiveness to methacholine was increased by a previous indirect challenge in EVH+ athletes only. The mechanisms for such increase remain to be determined. MIT and EVH should ideally be performed on separate occasions as there is a small but possible risk to obtain a false-positive response to methacholine when performed immediately after the EVH.

Trial Registration

ClinicalTrials.gov NCT00686491

Eosinophils and the ovalbumin mouse model of asthma

Mouse models of asthma are essential to understand asthma pathogenesis and eosinophil recruitment in the airways, and to develop new therapeutic strategies. Animal models try to mimic features of the human disease including airway hyperresponsiveness (AHR), eosinophilic inflammation, and remodeling, which are the typical asthma-related characteristics. The mouse is now the species of choice for asthma research due to the availability of transgenic animals and a wide array of specific reagents and techniques available. Cellular responses may be studied with innovative imaging and flow cytometry methods while lung mechanics may be precisely measured by the forced oscillation technique, and airway responsiveness approached by barometric plethysmography in conscious and unconstrained animals. Here, we describe procedures to generate acute models of hypereosinophilic asthma in mice, with ovalbumin (OVA) as the allergen. The presented allergic asthma models offer a large and reproducible eosinophil recruitment, measured in the bronchoalveolar lavage (BAL), accompanied with AHR, inflammation, and remodeling, and are particularly suited to assess the activity of drug candidates. We here present the classical 21-day allergic asthma model to OVA, and adjustments for a rapid 8-day model of airway allergic hypereosinophilia, and a more chronic 57-day model suitable for C57BL/6 mice to develop AHR together with airway eosinophilic inflammation and remodeling.

Inhibitory effects of kaempferol-3-O-rhamnoside on ovalbumin-induced lung inflammation in a mouse model of allergic asthma

The modification of natural flavonoid by glycosylation alters their physicochemical and pharmacokinetic properties, such as increased water solubility and stability, reduced toxicity, and sometimes enhanced or even new pharmacological activities. Kaempferol (KF), a plant flavonoid, and its glycosylated derivative, kaempferol-3-O-rhamnoside (K-3-rh), were evaluated and compared for their anti-inflammatory, anti-oxidant, and anti-asthmatic effects in an asthma model mouse. The results showed that K-3-rh fully maintained its anti-inflammatory and anti-asthmatic effects compared with KF in an asthma model mouse. Both KF and K-3-rh significantly reduced the elevated inflammatory cell numbers in the bronchoalveolar lavage fluid (BALF). KF and K-3-rh also significantly inhibited the increase in Th2 cytokines (IL-4, IL-5, and IL-13) and TNF-α protein levels through inhibition of the phosphorylation Akt and effectively suppressed eosinophilia in a mouse model of allergic asthma. The total immunoglobulin (Ig) E levels in the serum and BALF were also blocked by KF and K-3-rh to similar extents. K-3-rh exerts similar or even slightly higher inhibitory effects on Th2 cytokines and IgE production compared with KF, whereas K-3-rh was less effective at DPPH radical scavenging and the inhibition of ROS generation in inflammatory cells compared with KF. These results suggested that the K-3-rh, as well as KF, may also be a promising candidate for the development of health beneficial foods or therapeutic agents that can prevent or treat allergic asthma.

Relationship between the baseline alveolar volume-to-total lung capacity ratio and airway responsiveness

BACKGROUND AND OBJECTIVE

Ventilation heterogeneity (VH) has been linked to airway responsiveness (AR) based on various measures of VH involving inert gas washout, forced oscillation and lung imaging. We explore whether VH at baseline, as measured by the simple ratio of single breath alveolar volume to plethysmographically determined total lung capacity (VA/TLC), would correlate with AR as measured by methacholine challenge testing.

METHODS

We analysed data from spirometry, lung volumes, diffusing capacity and methacholine challenge to derive the VA/TLC and the dose-response slope (DRS) of forced expiratory volume in 1 s (DRS-FEV1) during methacholine challenge from 136 patients. We separated out airway closure versus narrowing by examining the DRS for forced vital capacity (DRS-FVC) and the DRS for FEV1/FVC (DRS-FEV1/FVC), respectively. Similarly, we calculated the DRS for sGaw (DRS-sGaw) as another measure of airway narrowing. We performed statistical analysis using Spearman rank correlation and multifactor linear regression using a backward stepwise modelling procedure.

RESULTS

We found that the DRS-FEV1 correlated with baseline VA/TLC (rho = -0.26, P < 0.01), and VA/TLC and FEV1 were independently associated with DRS-FEV1 (R(2)  = 0.14, P = 0.01). In addition, VA/TLC was associated with both airway narrowing and closure in response to methacholine.

CONCLUSIONS

These results confirm that baseline VA/TLC is associated with AR, and reflects both airway closure and airway narrowing following methacholine challenge.

Antihistamine Effect of a Pure Bioactive Compound Isolated from Slug (Diplosolenodes occidentalis) Material

OBJECTIVE

Folklore claims of the therapeutic effect of garden slug (Diplosolenodes occidentalis) extract used to relieve bronchoconstriction in asthmatic individuals were never validated scientifically. The aim of this study was to isolate the pure bioactive compound from slug extract causing this effect.

METHODS

The crude ground material was prepared in ethanol and after filtration, separation by flash column chromatography method was done. The structure was elucidated by data from hydrogen and carbon nuclear magnetic resonance (NMR) profiles. The bioactive compound was assessed for dose-dependent response effects on guinea pig tracheal smooth muscle pre-contracted with histamine. Receptor specificity studies were done by using HTMT dimaleate (H1 agonist). The type of antagonism was also identified.

RESULTS

The pure component isolated from garden slug material was identified by spectral studies as glyceryl trilinolenate (GT). It caused dose-dependent relaxation in guinea pig tracheal smooth muscle strips pre-contracted with histamine, it acted via H1 type receptors and showed non-competitive antagonism.

CONCLUSION

Glyceryl trilinolenate produced dose-dependent relaxation in tracheal smooth muscle strips in the presence of the agonist histamine. Glyceryl trilinolenate displayed non-competitive antagonism at H1 receptors in the trachea. This agent was able to alleviate bronchoconstriction in individuals presenting with atopic asthma in rural agricultural areas in Jamaica (verbal communications). It is possible that GT can be useful therapeutically to produce tracheal smooth muscle relaxation in individuals presenting with atopic asthma.

Ventilation heterogeneity in asthma

Non-uniform distribution of inspired gas within the lung, termed ventilation heterogeneity, is present in patients with even mild asthma. Current evidence strongly supports ventilation heterogeneity as a fundamental derangement of lung function in asthma that contributes per se to hypoxemia and airway hyper-responsiveness. An extreme example of ventilation heterogeneity is the identification by hyperpolarized gas MRI of lung regions with no ventilation, termed filling defects. Lung filling defects in patients with asthma can persist over time, increase in size with methacholine-induced bronchospasm and more likely are caused by obstruction of the peripheral and not the proximal airways. Ventilation heterogeneity can be quantified in the conducting and acinar lung zones with the multiple gas washout method, and in the acinar zone does not fully resolve following bronchodilator treatment in patients with asthma. In prospective studies, the degree of ventilation heterogeneity at baseline predicts airway hyper-responsiveness and response to corticosteroid dose titration. An important unanswered question is the relationship of airways inflammation to ventilation heterogeneity. In consideration of the importance of ventilation heterogeneity in its pathobiology, asthma is more a focal disorder with regional pathology akin to regional ileitis and not the generalized disorder of the airways as it has been viewed in the past.

CD4+ T cells enhance the unloaded shortening velocity of airway smooth muscle by altering the contractile protein expression

Abundant data indicate that pathogenesis in allergic airways disease is orchestrated by an aberrant T-helper 2 (Th2) inflammatory response. CD4(+) T cells have been localized to airway smooth muscle (ASM) in both human asthmatics and in rodent models of allergic airways disease, where they have been implicated in proliferative responses of ASM. Whether CD4(+) T cells also alter ASM contractility has not been addressed. We established an in vitro system to assess the ability of antigen-stimulated CD4(+) T cells to modify contractile responses of the Brown Norway rat trachealis muscle. Our data demonstrated that the unloaded velocity of shortening (Vmax) of ASM was significantly increased upon 24 h co-incubation with antigen-stimulated CD4(+) T cells, while stress did not change. Enhanced Vmax was dependent upon contact between the CD4(+) T cells and the ASM and correlated with increased levels of the fast (+)insert smooth muscle myosin heavy chain isoform. The levels of myosin light chain kinase and myosin light chain phosphorylation were also increased within the muscle. The alterations in mechanics and in the levels of contractile proteins were transient, both declining to control levels after 48 h of co-incubation. More permanent alterations in muscle phenotype might be attainable when several inflammatory cells and mediators interact together or after repeated antigenic challenges. Further studies will await new tissue culture methodologies that preserve the muscle properties over longer periods of time. In conclusion, our data suggest that inflammatory cells promote ASM hypercontractility in airway hyper-responsiveness and asthma.

Early life arsenic exposure and acute and long-term responses to influenza A infection in mice

BACKGROUND

Arsenic is a significant global environmental health problem. Exposure to arsenic in early life has been shown to increase the rate of respiratory infections during infancy, reduce childhood lung function, and increase the rates of bronchiectasis in early adulthood.

OBJECTIVE

We aimed to determine if early life exposure to arsenic exacerbates the response to early life influenza infection in mice.

METHODS

C57BL/6 mice were exposed to arsenic in utero and throughout postnatal life. At 1 week of age, a subgroup of mice were infected with influenza A. We then assessed the acute and long-term effects of arsenic exposure on viral clearance, inflammation, lung structure, and lung function.

RESULTS

Early life arsenic exposure reduced the clearance of and exacerbated the inflammatory response to influenza A, and resulted in acute and long-term changes in lung mechanics and airway structure.

CONCLUSIONS

Increased susceptibility to respiratory infections combined with exaggerated inflammatory responses throughout early life may contribute to the development of bronchiectasis in arsenic-exposed populations.

A nebulized complex traditional Chinese medicine inhibits Histamine and IL-4 production by ovalbumin in guinea pigs and can stabilize mast cells in vitro

Background

Traditional Chinese medicines have been used for anti-asthma treatment for several centuries in many Asian countries, and have been shown to effectively relieve symptoms. Our previous study demonstrated that a complex traditional Chinese medicine (CTCM) administered in nebulized form through the intratracheal route is effective against early-phase air-flow obstruction and can inhibit IL-5 production in ovalbumin (OVA)-sensitized guinea pigs. However, the antiasthmatic mechanisms of CTCMs are still unclear.

Methods

In this study, we examined the underlying mechanism of a CTCM that we used in our previous study in order to ascertain its function in the early-phase response to OVA challenge.

In each group, 10–12 unsensitized or OVA-sensitized guinea pigs were treated with nebulized CTCM before OVA challenge, and the airway responses of the animals to OVA were recorded. Bronchoalveolar lavage fluid (BALF) samples were collected 5 min after OVA challenge, and the histamine and IL-4 contents in the BALF were measured. P815 cells (a mouse mast cell line) were untreated or pretreated with CTCM or cromolyn sodium (a mast cell stabilizer), and incubated with Compound 48/80 (mast cell activator) for 9 hr. The levels of histamine and IL-4 released from the cells were quantified.

Results

We found that the inhibition of bronchoconstriction by the CTCM was attenuated by pretreatment with propranolol, suggesting that the CTCM has a bronchodilator effect that is associated with beta-adrenergic receptor. Our results also showed that the CTCM inhibited histamine and IL-4 secretion in the OVA-induced airway hypersensitivity in guinea pigs at 5 min post-OVA challenge, and in vitro study revealed that the CTCM is able to stabilize mast cells.

Conclusion

In conclusion, our results suggested that the CTCM is a kind of bronchodilator and also a mast cell stabilizer. Our findings provide useful information regarding the possible mechanism of the CTCM, and show its potential for application in the treatment of allergenic airway disease.

Acute Asthma Models to Ovalbumin in the Mouse

Human asthma is defined as a chronic inflammatory disease of the airways. Animal models are required to study asthma pathophysiology and identify and/or evaluate new therapeutic strategies. Several models of asthma have been developed in mice to mimic asthma symptoms, and can be divided in two groups as acute and chronic models. They are characterized by airway hyperresponsiveness (AHR), inflammation, and remodeling. Several experimental procedures have been implemented, the one mostly used being acute asthma models to ovalbumin. It comprises a sensitization step in the presence of aluminum hydroxide as an adjuvant, and a second step where mice are challenged with the allergen introduced directly into the airways to induce the modeled asthma features. This article describes procedures to efficiently and reproducibly obtain acute asthma features in mice, with ovalbumin as the allergen, which allow group comparisons and/or assessment of the activity of drug candidates. Curr. Protoc. Mouse Biol. 3:31-37 © 2013 by John Wiley & Sons, Inc.

Are mouse models of asthma appropriate for investigating the pathogenesis of airway hyper-responsiveness?

Whether mouse models of chronic asthma can be used to investigate the relationship between airway inflammation/remodeling and airway hyper-responsiveness (AHR) is a vexed question. It raises issues about the extent to which such models replicate key features of the human disease. Here, we review some of the characteristic pathological features of human asthma and their relationship to AHR and examine some limitations of mouse models that are commonly used to investigate these relationships. We compare these conventional models with our mouse model of chronic asthma involving long-term low-level inhalational challenge and review studies of the relationship between inflammation/remodeling and AHR in this model and its derivatives, including models of an acute exacerbation of chronic asthma and of the induction phase of childhood asthma. We conclude that while extrapolating from studies in mouse models to AHR in humans requires cautious interpretation, such experimental work can provide significant insights into the pathogenesis of airway responsiveness and its molecular and cellular regulation.

Airway closure on imaging relates to airway hyperresponsiveness and peripheral airway disease in asthma

The regional pattern and extent of airway closure measured by three-dimensional ventilation imaging may relate to airway hyperresponsiveness (AHR) and peripheral airways disease in asthmatic subjects. We hypothesized that asthmatic airways are predisposed to closure during bronchoconstriction in the presence of ventilation heterogeneity and AHR. Fourteen asthmatic subjects (6 women) underwent combined ventilation single photon emission computed tomography/computed tomography scans before and after methacholine challenge. Regional airway closure was determined by complete loss of ventilation following methacholine challenge. Peripheral airway disease was measured by multiple-breath nitrogen washout from which S(cond) (index of peripheral conductive airway abnormality) was derived. Relationships between airway closure and lung function were examined by multiple-linear regression. Forced expiratory volume in 1 s was 87.5 ± 15.8% predicted, and seven subjects had AHR. Methacholine challenge decreased forced expiratory volume in 1 s by 23 ± 5% and increased nonventilated volume from 16 ± 4 to 29 ± 13% of computed tomography lung volume. The increase in airway closure measured by nonventilated volume correlated independently with both S(cond) (partial R(2) = 0.22) and with AHR (partial R(2) = 0.38). The extent of airway closure induced by methacholine inhalation in asthmatic subjects is greater with increasing peripheral airways disease, as measured by ventilation heterogeneity, and with worse AHR.

Regulator of G protein signaling 2 is a key modulator of airway hyperresponsiveness

BACKGROUND

Drugs targeting individual G protein-coupled receptors are used as asthma therapies, but this strategy is limited because of G protein-coupled receptor signal redundancy. Regulator of G protein signaling 2 (RGS2), an intracellular selective inhibitor of multiple bronchoconstrictor receptors, may play a central role in the pathophysiology and treatment of asthma.

OBJECTIVE

We defined functions and mechanisms of RGS2 in regulating airway hyperresponsiveness (AHR), the pathophysiologic hallmark of asthma.

METHODS

Real-time PCR and Western blot were used to determine changes in RGS2 expression in ovalbumin-sensitized/-challenged mice. We also used immunohistochemistry and real-time PCR to compare RGS2 expression between human asthmatic and control subjects. The AHR of RGS2 knockout mice was assessed by using invasive tracheostomy and unrestrained plethysmography. Effects of loss of RGS2 on mouse airway smooth muscle (ASM) remodeling, contraction, intracellular Ca(2+), and mitogenic signaling were determined in vivo and in vitro.

RESULTS

RGS2 was highly expressed in human and murine bronchial epithelium and ASM and was markedly downregulated in lungs of ovalbumin-sensitized/-challenged mice. Lung tissues and blood monocytes from asthma patients expressed significantly lower RGS2 protein (lung) and mRNA (monocytes) than from nonasthma subjects. The extent of reduction of RGS2 on human monocytes correlated with increased AHR. RGS2 knockout caused spontaneous AHR in mice. Loss of RGS2 augmented Ca(2+) mobilization and contraction of ASM cells. Loss of RGS2 also increased ASM mass and stimulated ASM cell growth via extracellular signal-regulated kinase and phosphatidylinositol 3-kinase pathways.

CONCLUSION

We identified RGS2 as a potent modulator of AHR and a potential novel therapeutic target for asthma.

Targeting phosphoinositide 3-kinase γ in airway smooth muscle cells to suppress interleukin-13-induced mouse airway hyperresponsiveness

We recently reported that phosphoinositide 3-kinase γ (PI3Kγ) directly regulates airway smooth muscle (ASM) contraction by modulating Ca(2+) oscillations. Because ASM contraction plays a critical role in airway hyperresponsiveness (AHR) of asthma, the aim of the present study was to determine whether targeting PI3Kγ in ASM cells could suppress AHR in vitro and in vivo. Intranasal administration into mice of interleukin-13 (IL-13; 10 μg per mouse), a key pathophysiologic cytokine in asthma, induced AHR after 48 h, as assessed by invasive tracheostomy. Intranasal administration of a broad-spectrum PI3K inhibitor or a PI3Kγ-specific inhibitor 1 h before AHR assessment attenuated IL-13 effects. Airway responsiveness to bronchoconstrictor agonists was also examined in precision-cut mouse lung slices pretreated without or with IL-13 for 24 h. Acetylcholine and serotonin dose-response curves indicated that IL-13-treated lung slices had a 40 to 50% larger maximal airway constriction compared with controls. Furthermore, acetylcholine induced a larger initial Ca(2+) transient and increased Ca(2+) oscillations in IL-13-treated primary mouse ASM cells compared with control cells, correlating with increased cell contraction. As expected, PI3Kγ inhibitor treatment attenuated IL-13-augmented airway contractility of lung slices and ASM cell contraction. In both control and IL-13-treated ASM cells, small interfering RNA-mediated knockdown of PI3Kγ by 70% only reduced the initial Ca(2+) transient by 20 to 30% but markedly attenuated Ca(2+) oscillations and contractility of ASM cells by 50 to 60%. This report is the first to demonstrate that PI3Kγ in ASM cells is important for IL-13-induced AHR and that acute treatment with a PI3Kγ inhibitor can ameliorate AHR in a murine model of asthma.

Relevance of sensitization to occupational allergy and asthma in the detergent industry

There exists considerable historic experience of the relationship between exposure and both the induction of sensitization and the elicitation of respiratory symptoms from industrial enzymes of bacterial and fungal origin used in a wide variety of detergent products. The detergent industry in particular has substantial experience of how the control of exposure leads to limitation of sensitization with low risk of symptoms. However, the experience also shows that there are substantial gaps in knowledge, even when the potential occupational allergy problem is firmly under control, and also that the relationship between exposure and sensitization can be hard to establish. The latter aspect includes a poor appreciation of how peak exposures and low levels of exposure over time contribute to sensitization. Furthermore, while a minority of workers develop specific IgE, essentially none appear to have symptoms, a situation which appears to contradict the allergy dogma that, once sensitized, an individual will react to much lower levels of exposure. For enzymes, the expression of symptoms occurs at similar or higher levels than those that cause induction. In spite of some knowledge gaps, medical surveillance programs and constant air monitoring provide the tools for successful management of enzymes in the occupational setting. Ultimately, the knowledge gained from the occupational setting facilitates the completion of safety assessments for consumer exposure to detergent enzymes. Such assessments have been proven to be correct by the decades of safe use both occupationally and in consumer products.

Fisetin, a bioactive flavonol, attenuates allergic airway inflammation through negative regulation of NF-κB

Persistent activation of nuclear factor-κB (NF-κB) has been associated with the development of asthma. Fisetin (3,7,3',4'-tetrahydroxyflavone), a naturally occurring bioactive flavonol, has been shown to inhibit NF-κB activity. We hypothesized that fisetin may attenuate allergic asthma via negative regulation of the NF-κB activity. Female BALB/c mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was assessed for total and differential cell counts, and cytokine and chemokine levels. Lung tissues were examined for cell infiltration and mucus hypersecretion, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Fisetin dose-dependently inhibited ovalbumin-induced increases in total cell count, eosinophil count, and IL-4, IL-5 and IL-13 levels recovered in bronchoalveolar lavage fluid. It attenuated ovalbumin-induced lung tissue eosinophilia and airway mucus production, mRNA expression of adhesion molecules, chitinase, IL-17, IL-33, Muc5ac and inducible nitric oxide synthase in lung tissues, and airway hyperresponsiveness to methacholine. Fisetin blocked NF-κB subunit p65 nuclear translocation and DNA-binding activity in the nuclear extracts from lung tissues of ovalbumin-challenged mice. In normal human bronchial epithelial cells, fisetin repressed TNF-α-induced NF-κB-dependent reporter gene expression. Our findings implicate a potential therapeutic value of fisetin in the treatment of asthma through negative regulation of NF-κB pathway.

Molecular expression and functional role of canonical transient receptor potential channels in airway smooth muscle cells

Multiple canonical or classic transient receptor potential (TRPC) molecules are expressed in animal and human airway smooth muscle cells (SMCs). TRPC3, but not TRPC1, is a major molecular component of native non-selective cation channels (NSCCs) to contribute to the resting [Ca(2+)](i) and muscarinic increase in [Ca(2+)](i) in freshly isolated airway SMCs. TRPC3-encoded NSCCs are significantly increased in expression and activity in airway SMCs from ovalbumin-sensitized/challenged "asthmatic" mice, whereas TRPC1-encoded channel activity, but not its expression, is largely augmented. The upregulated TRPC3- and TRPC1-encoded NSCC activity both mediate "asthmatic" membrane depolarization in airway SMCs. Supportively, tumor necrosis factor-α (TNFα), an important asthma mediator, increases TRPC3 expression, and TRPC3 gene silencing inhibits TNFα-mediated augmentation of acetylcholine-evoked increase in [Ca(2+)](i) in passaged airway SMCs. In contrast, TRPC6 gene silencing has no effect on 1-oleoyl-2-acetyl-sn-glycerol (OAG)-evoked increase in [Ca(2+)](i) in primary isolated cells. These findings provide compelling information indicating that TRPC3-encoded NSCCs are important for physiological and pathological cellular responses in airway SMCs. However, continual studies are necessary to further determine whether, which, and how TRPC-encoded channels are involved in cellular responses in normal and diseased (e.g., asthmatic) airway SMCs.

Effect of inhibition of the ubiquitin-proteasome-system and IκB kinase on airway inflammation and hyperresponsiveness in a murine model of asthma

The current treatment of asthma is far from optimal and there is a need for novel therapeutic approaches. NFkB has recently been highlighted as an important pro-inflammatory transcriptional factor and its blockade is believed to represent a new therapeutic approach for asthma. The purpose of this study is to investigate the effects of blocking the actions of NFkB, through inhibition of the ubiquitin-proteasome system (UPS) or IkB kinase (IKK), in a murine model of asthma. Treatment with the UPS inhibitor, MG-132 (0.03 and 0.1 mg/kg), did not significantly affect the ovalbumin-induced increase in total and differential cell numbers, histological changes such as perivascular and peribronchial inflammatory cell infiltration, perivascular and peribronchial fibrosis or the increased Penh to methacholine. In contrast, treatment of mice with the IKK inhibitor, BAY 11-7085, (3 and 10 mg/kg) dose-dependently inhibited the ovalbumin-induced increase in airway leukocyte influx and decreased the percentage of airway lymphocytes, neutrophils and eosinophils. Also, BAY 11-7085-treated (10 mg/kg) mice showed a significant decrease in the histologically assessed inflammatory indices as well as a significant reduction in the ovalbumin-induced increase in Penh to inhaled methacholine. Furthermore, BAY 11-7085 significantly inhibited the ovalbumin-induced increase in the level of phosphorylation of IkBalpha and extracellular regulated kinases (ERK) 1/2, whilst MG-132 significantly increased the phosphorylation of (ERK) 1/2. These findings confirm the critical role that NFkB plays in airway inflammation, highlight the importance of IKK in regulating the pro-inflammatory activity of NFkB and also suggest that UPS may not be a useful drug target for asthma treatment.

Application of texture analysis to ventilation SPECT/CT data

It is demonstrated that textural parameters calculated from functional pulmonary CT data have the potential to provide a robust and objective quantitative characterisation of inhomogeneity in lung function and classification of lung diseases in routine clinical applications. Clear recommendations are made for optimum data preparation and textural parameter selection. A new set of platform-independent software tools are presented that are implemented as plug-ins for ImageJ. The tools allow segmentation and subsequent histogram-based and grey-level co-occurrence matrix based analysis of the regions of interest. The work-flow is optimised for use in a clinical environment for the analysis of transverse Computed Tomography (CT) scans and lung ventilation scans based on SPECT. Consistency tests are made against other texture analysis plug-ins and simulated lung CT data. The same methods are then applied to patient data consisting of a healthy reference group and one patient group each who suffered from asthma, chronic obstructive pulmonary disease (COPD), and COPD plus lung cancer. The potential for disease classification based on computer analysis is evaluated.

Behavioral inhibition is associated with airway hyperresponsiveness but not atopy in a monkey model of asthma

OBJECTIVE

To determine whether indicators of behavioral inhibition and cortisol responses to stressful situations, obtained in infancy, were associated with asthma-related measures (atopy and airway hyperresponsiveness [AHR]) approximately 2 years later.

METHODS

Measures reflecting inhibited temperament and cortisol response after a 25-hour separation from mother and relocation to a novel room were obtained for 21 rhesus monkeys (mean age, 109 days; range, 91-122 days). Inhibited temperament was measured by reduced emotionality and increased vigilance. Atopy and AHR were assessed after 2 years (age range, 19-35 months) using skin tests to common aeroallergens and inhaled methacholine challenge, respectively.

RESULTS

No associations were found between atopy and either behavioral inhibition or cortisol levels (p > .56). Low emotionality was associated with AHR (r = 0.47, p = .03), and a trend was found for blunted cortisol responsiveness and AHR (r = 0.42, p = .06).

CONCLUSIONS

Inhibited temperament and blunted cortisol responsiveness may be related to the development of AHR that is common to both nonatopic and atopic asthma phenotypes and may indicate risk for nonatopic asthma specifically.

Multiscale mathematical models of airway constriction and disease

Loss of lung function in airway disease frequently involves many complex phenomena and interconnected underlying causes. In many conditions, such as asthmatic airway hyper-responsiveness, hypothesised underlying causes span multiple spatial scales. In cases like this, it is insufficient to take a reductionist approach, wherein each subsystem (at a given spatial scale) is considered in isolation and then the whole is taken to be merely the sum of the parts; this is because there can be significant and important interactions and synergies between spatial scales. Experimentally this can manifest as, for example, significant differences between behaviour in isolated tissue and that seen in vivo, while from a modelling perspective, it necessitates multiscale modelling approaches. Because it is precisely in these complex environs that models have the greatest potential to improve understanding of underlying behaviours, these multiscale models are of particular importance. This paper reviews several examples of multiscale models from the most important models in the literature, with a particular emphasis on those concerned with airway hyper-responsiveness and airway constriction.

Could an increase in airway smooth muscle shortening velocity cause airway hyperresponsiveness?

Airway hyperresponsiveness (AHR) is a characteristic feature of asthma. It has been proposed that an increase in the shortening velocity of airway smooth muscle (ASM) could contribute to AHR. To address this possibility, we tested whether an increase in the isotonic shortening velocity of ASM is associated with an increase in the rate and total amount of shortening when ASM is subjected to an oscillating load, as occurs during breathing. Experiments were performed in vitro using 27 rat tracheal ASM strips supramaximally stimulated with methacholine. Isotonic velocity at 20% isometric force (Fiso) was measured, and then the load on the muscle was varied sinusoidally (0.33 ± 0.25 Fiso, 1.2 Hz) for 20 min, while muscle length was measured. A large amplitude oscillation was applied every 4 min to simulate a deep breath. We found that: 1) ASM strips with a higher isotonic velocity shortened more quickly during the force oscillations, both initially (P < 0.001) and after the simulated deep breaths (P = 0.002); 2) ASM strips with a higher isotonic velocity exhibited a greater total shortening during the force oscillation protocol (P < 0.005); and 3) the effect of an increase in isotonic velocity was at least comparable in magnitude to the effect of a proportional increase in ASM force-generating capacity. A cross-bridge model showed that an increase in the total amount of shortening with increased isotonic velocity could be explained by a change in either the cycling rate of phosphorylated cross bridges or the rate of myosin light chain phosphorylation. We conclude that, if asthma involves an increase in ASM velocity, this could be an important factor in the associated AHR.

Thymic stromal lymphopoietin in cigarette smoke-exposed human airway smooth muscle

Thymic stromal lymphopoietin (TSLP) is a newly identified IL-7-like cytokine known to be expressed in airway biopsies of patients with asthma and chronic obstructive pulmonary disease. As both diseases may be induced or exacerbated by cigarette smoking, it is possible that TSLP represents an important link between cigarette smoke exposure and inflammatory signaling in the airways. In this regard, TSLP appears to also be expressed in airway smooth muscle (ASM); however, its role is unknown. In the current study, we examined TSLP and the TSLP receptor (TSLP-R) expression and function in human ASM cells under normal conditions and following exposure to cigarette smoke extract (CSE). Western blot analysis of human ASM cells showed significant expression of TSLP and TSLP-R, with increased expression of both by overnight exposure to 1 or 2% CSE. Furthermore, CSE increased TSLP release by ASM. In parallel experiments using enzymatically dissociated human ASM cells loaded with the Ca(2+) indicator fura 2-AM and imaged using fluorescence microscopy, we evaluated the effects of CSE exposure on intracellular Ca(2+) ([Ca(2+)](i)) responses to agonist stimulation. [Ca(2+)](i) responses to histamine were increased with overnight CSE exposure. Exposure to TSLP also resulted in elevated responses, which were blunted by TSLP and TSLP-R Abs. Importantly, the enhancing effects of CSE on [Ca(2+)](i) responses were also blunted by these Abs. These effects were associated with CSE- and TSLP-induced changes in STAT5 phosphorylation. Overall, these novel data suggest that cigarette smoke, TSLP, and ASM are functionally linked and that cigarette smoke-induced increase in airway contractility may be mediated via ASM-derived increases in TSLP signaling.

A standardized aqueous extract of Anoectochilus formosanus modulated airway hyperresponsiveness in an OVA-inhaled murine model

Anoectochilus formosanus HAYATA, a Chinese herb, is a valued folk medicine for fever, pain, and diseases of the lung and liver. Allergic asthma is characterized by increased serum IgE level and inflammation of the airways with high levels of interleukin (IL)-4 and IL-5 in bronchoalveolar lavage fluids (BALF). Constriction of airway smooth muscle and development of airway hyperresponsiveness (AHR) are the most important symptoms of allergic asthma. In our previous study, a standardized aqueous extract of A. formosanus (SAEAF) was used to modulate innate immunity of normal mice. In this study, airway inflammatory infiltrations, including T cell differentiation, cytokine modulation, allergic antibodies estimation, pulmonary pathology, and enhanced pause (Penh) of AHR were used to evaluate SAEAF treatment of an ovalbumin (OVA)-inhaled airway allergic murine model. The resulting cytokine profiles demonstrated that SAEAF can significantly reduce Th2 polarization after administration of SAEAF in OVA inhalation. These results also suggest that SAEAF modulates cytokine secretion in allergic asthma. Modulated natural T regulatory cells (CD25+/CD4+, Treg) were also shown to increase immuno-suppression in the allergic lung inflammation and further down-regulate airway inflammatory infiltration in eosinophils and macrophages. Finally, decreased airway anti-OVA IgE secretion and reduced AHR were observed. Our results indicate that the administration of SAEAF can modulate cytokines and T cell subpopulation by regulating inflammatory cell infiltration and modulating the allergic response.

Anti-inflammatory and immunosuppressive effects of the enaminone E121

Asthma is a chronic inflammatory disease of the airways. The treatment of asthma is far from optimal and hence the need for novel therapeutic agents exists. The purpose of this study was to assess the anti-asthma effects of an enaminone, E121, and also its effects on human peripheral blood mononuclear cell proliferation and cytokine release. The effects of E121 were assessed in an ovalbumin-induced model of airway inflammation and airway hyperresponsiveness. In addition, the effects of E121 on phytohemagglutinin (PHA), anti-CD3 monoclonal antibody and lipopolysaccharide (LPS)-induced human peripheral blood mononuclear cell proliferation and cytokine release, respectively, were assessed. Treatment of mice with E121 significantly decreased the ovalbumin-induced increase in airway total cell influx and eosinophil infiltration and this was associated with an inhibition of ovalbumin-induced airway hyperresponsiveness. Moreover, E121 reduced PHA and anti-CD3-induced human peripheral blood mononuclear cell proliferation in vitro. E121 also inhibited PHA, anti-CD3 monoclonal antibody and LPS-induced cytokine release from human peripheral blood mononuclear cell cultures. These findings indicate that E121 exhibits anti-inflammatory and immunosuppressive activities.

Interferon-gamma and pulmonary macrophages contribute to the mechanisms underlying prolonged airway hyperresponsiveness

BACKGROUND

Airway hyperresponsiveness (AHR) in asthmatics includes a variable component that persists following an allergen challenge. This may be dissociated from inflammatory cell recruitment, implying a role for resident pulmonary cells in regulating the response.

OBJECTIVE

Using improved methods of assessing AHR in a mouse model of allergic airway disease, to investigate the basis of the development of prolonged AHR.

METHOD

BALB/c mice were systemically sensitized and then challenged with aerosolized ovalbumin (OVA). Airway and tissue responsiveness were measured at baseline and at 1 day, and 1, 2 and 3 weeks after the last OVA challenge. Inflammatory cell numbers in BALF and levels of mRNA for eotaxin-1 and -2, IFN-gamma, IL-5 and -13 in the lung were measured at each time-point. In further experiments, the roles of IFN-gamma and of CCR3(+) and CD4(+) cells in the development of prolonged AHR were assessed by blockade or depletion with monoclonal antibodies. The role of pulmonary macrophages was assessed by selective chemical depletion of these cells.

RESULTS

Airway responsiveness was increased above baseline at 1 day after the last OVA challenge, and this was sustained for 1 week. In contrast, tissue-specific responsiveness was only significantly increased above baseline at 1 day. Development of prolonged AHR was inhibited by neutralization of IFN-gamma or by depletion of pulmonary macrophages, but not by depletion of either CD4(+) T cells or CCR3(+) eosinophils.

CONCLUSION

An interaction between IFN-gamma and pulmonary macrophages contributed to the prolongation of airway hyperresponsiveness. In contrast, T cells and eosinophils did not contribute to prolongation of AHR. These findings emphasize the importance of the innate host response in the development of manifestations of asthma, as well as its potential relevance as a target for therapeutic intervention.