Hallmark Of Asthma Research Articles

Butyrate ameliorates allergic airway inflammation by limiting eosinophil trafficking and survival

Lung eosinophilia is a hallmark of asthma, and eosinophils are believed to play a crucial role in the pathogenesis of allergic inflammatory diseases. Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are produced in high amounts in the gastrointestinal tract by commensal bacteria and can be absorbed into the bloodstream. Although there is recent evidence that SCFAs are beneficial in allergic asthma models, the effect on eosinophils has remained elusive. The role of SCFAs was investigated in human eosinophil function and a mouse model of allergic asthma. Eosinophils were purified from self-reported allergic or healthy donors. Migration, adhesion to the endothelium, and eosinophil survival were studied invitro. Ca2+ flux, apoptosis, mitochondrial membrane potential, and expression of surface markers were determined by using flow cytometry and in part by using real-time PCR. Allergic airway inflammation was assessed invivo in an ovalbumin-induced asthma model by using invasive spirometry. For the first time, we observed that SCFAs were able to attenuate human eosinophils at several functional levels, including (1) adhesion to the endothelium, (2) migration, and (3)survival. These effects were independent from GPR41 and GPR43 but were accompanied by histone acetylation and mimicked by trichostatin A, a pan-histone deacetylase inhibitor. Invivo butyrate ameliorated allergen-induced airway and lung eosinophilia, reduced type 2 cytokine levels in bronchial fluid, and improved airway hyperresponsiveness in mice. These invitro and invivo findings highlight the importance of SCFAs, especially butyrate as a promising therapeutic agent in allergic inflammatory diseases.

Induction of asthma causes sensitization of the carotid bodies to lysophosphatidic acid

Previously, we demonstrated an important role for the carotid bodies in asthmatic bronchoconstriction. Specifically, we showed that an allergen‐induced increase in circulating lysophosphatidic acid (LPA) in asthmatic rats activates LPA receptors (LPAr) in the carotid bodies and post‐ganglionic TRPV1 channels, provoking vagal activity and thereby triggering acute bronchoconstriction (Jendzjowsky et al. 2018 Nat Comm. 9, 4030). Here we report that induction of asthma causes molecular and functional changes to the carotid bodies that sensitize them to LPA.Experiments were carried out using the standard ovalbumin‐sensitized brown Norway rat model of asthma. Carotid bodies and petrosal ganglia were extracted 3 hours after the third ovalbumin challenge in asthmatic (OVA) or third saline challenge in naïve (N) rats. Using qPCR (Δctt OVA vs N), LPAr expression was increased in the carotid body (LPAr1: 556x; LPAr2: 20x; LPAr3: 2x; LPAr4: 150x; LPAr5 only detected in OVA: LPAr6: 175x; TRPV1 not detected, as demonstrated previously Roy et al. 2012 J Appl Physiol 112:212–224) whereas LPAr 1–6 and TRPV1 were similarly expressed in petrosal ganglia of OVA and N rats. Using the perfused ex vivo carotid body preparation, baseline normalized carotid sinus nerve responses to increasing doses of LPA activity, were significantly augmented in OVA compared to N rats (2.5uM‐ OVA: 1.12 ± 0.01 N: 1.05 ± 0.02, p=0.162; 5uM: OVA: 1.23 ± 0.03 N:1.10 ± 0.02, p=0.009; 10uM: OVA: 1.40 ± 0.07 N: 1.17 ± 0.03, p<0.001). In contrast, carotid body activity in response to hypoxia was not different between OVA (2.54 ± 0.47) and N (1.95 ± 0.10) rats (p=0.243).Our data suggest that asthmatic carotid bodies have enhanced responsiveness to LPA, independent of hypoxic sensitivity. These changes likely contribute to the acute allergen‐induced bronchoconstriction which is the hallmark of asthma that appears to be mediated, in part, by a novel carotid body‐vagal‐lung neuronal pathway. Targeting carotid body LPA signalling may reduce asthmatic bronchoconstriction and provide new pharmaceutical targets for inflammatory lung disease.Support or Funding InformationThis project was funded by The Lung Association and Canadian Institute for Health Research.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Asthmatic bronchial epithelial cells promote the establishment of a Hyaluronan-enriched, leukocyte-adhesive extracellular matrix by lung fibroblasts

BackgroundAirway inflammation is a hallmark of asthma. Alterations in extracellular matrix (ECM) hyaluronan (HA) content have been shown to modulate the recruitment and retention of inflammatory cells. Bronchial epithelial cells (BECs) regulate the activity of human lung fibroblasts (HLFs); however, their contribution in regulating HLF production of HA in asthma is unknown. In this study, we tested the hypothesis that BECs from asthmatic children promote the generation of a pro-inflammatory, HA-enriched ECM by HLFs, which promotes the retention of leukocytes.MethodsBECs were obtained from well-characterized asthmatic and healthy children ages 6–18 years. HLFs were co-cultured with BECs for 96 h and samples were harvested for analysis of gene expression, synthesis and accumulation of HA, and subjected to a leukocyte adhesion assay with U937 monocytes.ResultsWe observed increased expression of HA synthases HAS2 and HAS3 in HLFs co-cultured with asthmatic BECs. Furthermore, we demonstrated greater total accumulation and increased synthesis of HA by HLFs co-cultured with asthmatic BECs compared to healthy BEC/HLF co-cultures. ECM generated by HLFs co-cultured with asthmatic BECs displayed increased HA-dependent adhesion of leukocytes in a separate in vitro binding assay.ConclusionsOur findings demonstrate that BEC regulation of HA production by HLFs is altered in asthma, which may in turn promote the establishment of a more leukocyte-permissive ECM promoting airway inflammation in this disease.

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

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

IFN-γ Influences Epithelial Antiviral Responses via Histone Methylation of the RIG-I Promoter.

The asthmatic lung is prone to respiratory viral infections that exacerbate the symptoms of the underlying disease. Recent work has suggested that a deficient T-helper cell type 1 response in early life may lead to these aberrant antiviral responses. To study the development of long-term dysregulation of innate responses, which is a hallmark of asthma, we investigated whether the inflammatory environment of the airway epithelium can modulate antiviral gene expression via epigenetic mechanisms. We primed AALEB cells, a human bronchial epithelial cell line, with IFN-γ and IL-13, and subsequently infected the cells with respiratory syncytial virus (RSV). We then analyzed the expression of innate antiviral genes and their epigenetic markers. Priming epithelial cells with IFN-γ reduced the RSV viral load. Microarray analysis identified that IFN-γ priming enhanced retinoic acid-inducible gene (RIG)-I mRNA expression, and this expression correlated with epigenetic changes at the RIG-I promoter that influenced its transcription. Using chromatin immunoprecipitation, we observed a reduction of trimethylated histone 3 lysine 9 at the RIG-I promoter. Addition of inhibitor BIX-01294 to this model indicated an involvement of lysine methyltransferase G9a in RIG-I epigenetic regulation. These data suggest that prior exposure to IFN-γ may leave an epigenetic mark on the chromatin that enhances airway cells' ability to resist infection, possibly via epigenetic upregulation of RIG-I. These observations provide further evidence for a crucial role of IFN-γ in the development of mature antiviral responses within a model of respiratory infection. Further clinical validation is required to determine whether this effect in early life leads to changes in antiviral responses associated with asthma.

TLR4 antagonist suppresses airway remodeling in asthma by inhibiting the T-helper 2 response.

Airway remodeling is a hallmark of bronchial asthma. Our group has previously reported that the thymic stromal lymphopoietin (TSLP), an airway epithelial-derived cytokine, has a central role in the pathogenesis of airway remodeling, and that toll-like receptor (TLR) 4 signaling in epithelial cells may trigger T-helper 2 (Th2) immune responses by overexpression of TSLP. However, it is currently unclear whether TLR4 is a target in the treatment of airway remodeling in asthma. The present study established a house dust mite (HDM)-induced chronic asthmatic model in female BALB/c mice and treated the HDM-exposed mice with 3 mg/kg TAK242, as a TLR4 antagonist, 30 min prior to HDM challenge for up to 2 weeks. General structural changes in the airways were subsequently evaluated and the levels of TSLP in the bronchoalveolar lavage fluid (BALF) and interleukin (IL)-4, IL-13 and interferon (IFN)-γ in the blood serum were determined. Results indicated that TAK242 treatment markedly reduced pathological changes in the airways of HDM-induced asthmatic mice, as demonstrated by reductions in airway wall thickening, peribronchial collagen deposition and subepithelial fibrosis. Furthermore, airway hyperresponsiveness to inhaled methacholine and the levels of TSLP in the BALF and IL-4, IL-13 and IFN-γ in the peripheral blood were significantly reduced by TAK242 treatment (P<0.05). Furthermore, the shift in the IFN-γ/IL-4 ratio induced by HDM treatment was significantly reversed following TAK242 pretreatment, which indicated that TAK242 modulated Th1/Th2 immune homeostasis in the chronic asthma mouse model. The present findings in a chronic asthma mouse model suggest that TAK242 may be an efficient treatment for airway remodeling, possibly through the inhibition of TSLP overexpression and Th2 airway inflammation.

Overweight in childhood and adolescence: Does it lead to airway hyperresponsiveness in adulthood?

ABSTRACTBackground: Obesity is increasing worldwide among children and adolescents, and has been associated with an increased incidence of asthma. However, the mechanisms underlying this association are incompletely understood. Objective: In this cohort study we aimed to investigate whether being overweight in childhood and adolescence is associated with an increased risk of airway hyperresponsiveness (AHR), a hallmark of asthma, in early adulthood. Methods: Of 527 subjects from a random population sample of children and adolescents (7–17 years) examined at baseline, a total of 184 subjects completed the follow-up visit 20 years later and were included in the present analysis. Both visits included assessment of height and weight, case history and spirometry. At both visits, bronchial provocation tests were performed using either histamine (baseline) or methacholine (follow-up). In addition, fractional exhaled nitric oxide (FeNO) was measured at follow-up. Results: No significant difference in the prevalence of AHR at follow-up was found between subjects who were overweight or obese at baseline visit (n = 26) (pediatric definition, body mass index ≥ 85%percentile) and normal weight subjects (n = 158) (positive bronchial provocation tests: 15.4% vs. 22.2%, respectively, p = 0.35). Likewise, follow-up FeNO levels did not differ significantly between subjects who were lean and those who were overweight or obese at baseline (geometric mean (95% confidence interval [CI]) 15.1 (13.7, 16.6) parts per billion (ppb) versus 13.0 (10.6, 15.9) ppb, p = 0.23). Conclusion: In children and adolescents, being obese or overweight seems not to be associated with an increased risk of AHR or increased FeNO levels in early adulthood.

Prenatal stress challenge impairs fetal lung development and asthma severity sex-specifically in mice

Allergic asthma is an increasing health problem worldwide. Interestingly, prenatal challenges such as stress have been associated with an increased risk for asthma during childhood. The underlying pathogenesis of how prenatal stress increases the risk for asthma still remains unclear. Potential targets could be that the fetal immune ontogeny or fetal lung development are compromised by prenatal challenges. Here, we aimed to identify whether prenatal stress challenge affects fetal lung development in mice. C57BL/6 pregnant mice were challenged with sound stress and fetal lung development was assessed histologically. Whilst prenatal stress challenge did not profoundly affect lung development in male fetuses, it resulted in less extensive terminal sacs, surrounded by thicker mesenchymal tissue in female fetuses. Thus, prenatal stress disrupted fetal lung development sex-specifically. Interestingly, upon prenatal stress challenge, the airway hyperresponsiveness and eosinophilic inflammation- two hallmarks of asthma – were significantly increased in adult female offspring, whilst regulatory CD4+ T cells were reduced. These findings strongly underpin the sex-specific association between s challenged fetal development and a sex-specific altered severity of asthma in adult offspring. Our model now allows to identify maternal markers through which the risk for asthma and possible other diseases is vertically transferred before birth in response to challenges. Such identification then opens avenues for primary disease prevention.

TNFα enhances force generation in airway smooth muscle.

Airway inflammation is a hallmark of asthma, triggering airway smooth muscle (ASM) hyperreactivity and airway remodeling. TNFα increases both agonist-induced cytosolic Ca2+ concentration ([Ca2+]cyt) and force in ASM. The effects of TNFα on ASM force may also be due to an increase in Ca2+ sensitivity, cytoskeletal remodeling, and/or changes in contractile protein content. We hypothesized that 24 h of exposure to TNFα increases ASM force by changing actin and myosin heavy chain (MyHC) content and/or polymerization. Porcine ASM strips were permeabilized with 10% Triton X-100, and force was measured in response to increasing concentrations of Ca2+ (pCa 9.0 to 4.0) in control and TNFα-treated groups. Relative phosphorylation of the regulatory myosin light chain (p-MLC) and total actin, MLC, and MyHC concentrations were quantified at pCa 9.0, 6.1, and 4.0. Actin polymerization was quantified by the ratio of filamentous to globular actin at pCa 9.0 and 4.0. For determination of total cross-bridge formation, isometric ATP hydrolysis rate at pCa 4.0 was measured using an enzyme-coupled NADH-linked fluorometric technique. Exposure to TNFα significantly increased force across the range of Ca2+ activation but did not affect the intrinsic Ca2+ sensitivity of force generation. The TNFα-induced increase in ASM force was associated with an increase in total actin, MLC, and MyHC content, as well as an increase in actin polymerization and an increase in maximum isometric ATP hydrolysis rate. The results of this study support our hypothesis that TNFα increases force generation in ASM by increasing the number of contractile units (actin-myosin content) contributing to force generation.

Biomarkers of oxidative stress and antioxidants in severe asthma: A Prospective Case-Control Study

BackgroundBronchial airway inflammation is the hallmark of asthma, which may be driven by an imbalance between oxidative stress and antioxidant defenses. Antioxidants deficiency may play a role, but this has remained unconfirmed. ObjectiveTo evaluate the oxidative stress burden and antioxidants defenses in patients with increasing asthma severity. MethodsThis prospective case-control study compared fractional exhaled nitric oxide (FeNO), exhaled breath condensate nitrite/nitrate (EBC-NOx), spirometry, and serum vitamins and trace elements among patients with and without asthma. ResultsSixty participants were recruited (30 with severe asthma number; 23 women [76.7%]; mean age, 41.4 years; mean forced expiratory volume in 1 second [FEV1], 2.2 L [72.2% predicted]; mean inhaled corticosteroid dosage, 2,540 μg/d; 18/30 [60%] receiving maintenance oral corticosteroids; 15 with mild asthma; all corticosteroids naïve; 9 women [60%]; mean age, 34.6 years; mean FEV1, 3.48 L [100.5% predicted]; 15 healthy controls; 12 women [80%]; mean age, 37.6 years; and mean FEV1, 3.53 L [111.7% predicted]). The mean FeNO levels increased significantly with increasing asthma severity (P = .01), but the EBC-NOx levels did not change significantly (P = .90). Paradoxically, vitamin A and vitamin E increased with increased disease severity, with vitamin E levels increasing significantly (P = .07 and P < .001, respectively). There was no significant difference between groups in the levels of copper (P = .37), zinc (P = .97), or selenium (P = .90). ConclusionFeNO but not EBC-NOx is increased significantly with asthma severity with no evidence of vitamins or trace elements deficiency in severe asthma. Impaired oxidative stress defenses in severe asthma may be driven by factors other than vitamins or trace elements deficiency.

Stability of FeNO and airway hyperresponsiveness to mannitol in untreated asthmatics

ABSTRACTObjective: Airway hyperresponsiveness and airway inflammation are important hallmarks of asthma and are useful in asthma diagnosing, monitoring and treatment. The aim of the study was to assess whether two commonly used clinical tests, the mannitol challenge and Fraction of exhaled NO (FeNO), were stable clinical indicators over time in stable untreated asthmatics. Methods: 54 non-smoking, asthma patients not treated with steroids were enrolled in the study and assessed at baseline and a median of 6 months later. At baseline and follow-up, FeNO and airway hyperesponsiveness to mannitol were measured, and asthma control was assessed with the Asthma Control Questionnaire (ACQ). Results: A total of 41 subjects completed both visits. Mean (SD) FEV1% at baseline was 94.1% (17.7) and at re-examination 94.6% (19.7) (ns). The ACQ score was unchanged from baseline (Mean (SD): 0.90 (± 0.73)) to follow-up 0.90 (± 0.74) (ns), as was the FEV1% (94.1% (±17.1%) vs 94.6% (19.7%)(ns) indicating that patients were clinically stable during follow-up. The response to mannitol was unchanged at follow-up (Geometric mean (CI) of Response Dose Ratio (RDR) to mannitol: 0.026(0.013–0.046) vs 0.026(0.012–0.050) (ns). There was a slight decrease in FeNO at follow-up (25.5 ppb (19.7–32.9) to 21.9 ppb (17.1–28.2) (p < 0.001). Conclusions: In steroid-free non-smoking asthmatics with constant symptom scores and lung function, airway responsiveness to mannitol remained at the same level over a period of months, while a minor change in exhaled FeNO was reported. These results suggest that mannitol is a stable, reliable marker of clinical disease activity.

Inhaled Mannitol in the Diagnosis and the Management of Asthma

The need for a diagnostic test for asthma was established when it was realized that asthma symptoms could not be relied upon to predict the presence, or not, of airway hyper-responsiveness and inflammation, the hallmarks of asthma. A need to identify asthmatic patients who were overtreated or undertreated with inhaled corticosteroids (ICS) has also been recognized. Dry-powder mannitol, given by inhalation, is used as a bronchial provocation test to meet this need. Mannitol is an osmotic agent and causes the release of mediators that provoke the airways to narrow. This airway response to mannitol is dependent on the presence of inflammatory cells, and it is reduced or even completely inhibited by treatment with ICS. Studies in large populations have shown that mannitol has a high specificity (95%) for identifying asthma and can be used to monitor treatment with ICS. Importantly, when mannitol responsiveness is reduced by treatment with ICS, all other indices of airway inflammation are reduced, in association with improvements in clinical symptoms. The responsiveness to mannitol is more frequent than the responsiveness to exercise in both adults and children. Mannitol responsiveness is not necessarily associated with other markers of airway inflammation such as a high exhaled nitric oxide and/or a sputum eosinophilia. This may be due to mast cells being the important cell for the mannitol response. In adults, a negative mannitol test result is common in asthmatic patients taking ICS, and consideration should be given to the back titration of the dose to confirm the diagnosis and reduce risks from overtreatment.

Characteristics of Allergic Pulmonary Inflammation in CXCR3Knockout Mice Sensitized and Challenged with House Dust Mite Protein.

Chemokine C-X-C motif receptor 3 (CXCR3) is a chemokine receptor that is mainly expressed by activated T lymphocytes. T cells play important roles in allergic pulmonary inflammation, which is a hallmark of asthma and elicits the localized accumulation of activated T cells in the lung. In China, a marked increase in the incidence rate of chronic allergic pulmonary inflammation has made it a major public health threat. In the present study, we investigated the role of CXCR3 and its ligands in airway inflammation induced by house dust mite protein (HDMP) in a CXCR3 knockout (CXCR3KO) asthma mouse model. Pathological manifestations in the lung, cell counts and bronchoalveolar lavage fluid (BALF) classifications were studied using hematoxylin and eosin (H&E) staining. The levels of IL-4 and IFN-γ in the BALF and splenocyte supernatants were measured using ELISA. CD4+ and CD8+ T cells in the lung and spleen were analyzed by flow cytometry. RT-PCR was applied to measure the mRNA transcript levels of monokines induced by IFN-γ(CXCL9) and IFN-γ inducible protein 10(CXCL10). The total cell counts, eosinophil counts, and IL-4 levels in the BALF and cultured splenocyte supernatants were significantly increased, while the levels of IFN-γ were reduced in the HDMP groups(P<0.01). Changes in the total cell counts, eosinophil counts, and lymphocyte counts, as well as the total protein levels in the BALF, the levels of IL-4 in splenocyte supernatants, and the pathological manifestations in the lung, were all greater in CXCR3KO mice than in C57BL/6 wild-type mice. Furthermore, the expression levels of CXCL9 and CXCL10 mRNA transcripts in the lungs of CXCR3KO mice were lower than those in C57BL/6 wild-type mice (P<0.05). CXCR3 and its ligands (i.e., CXCL9 and CXCL10) may play anti-inflammatory roles in this animal model. Promoting the expression of CXCR3 and its ligands may represent a novel therapeutic approach for preventing and curing asthma.

What lies beyond Asthma Control Test: Suggestions for clinical practice

Background: Asthma Control Test (ACT ™) validity relies on Global Initiative for Asthma (GINA) definition of control. It includes neither reversibility nor inflammation assessment despite their importance as hallmark of asthma, partially unrelated to symptoms. Furthermore though rhinitis may affect the patient's perception of asthma control, its impact on ACT accuracy has not been systematically evaluated. Objective: To explore ACT validity according to a definition of control including: forced expiratory volume in 1 s (FEV1) ≥ 80%, negative reversibility test, exhaled nitric oxide at a flow rate of 50 ml/s (FeNO) < 50 ppb. Results: 177 asthmatics referring to our Unit have been studied. ACT with cut-off score ≥20 showed a good positive predictive value (83.5%) but low sensitivity (47.8%), specificity (66.7%), and negative predictive value (26.5%). ROC curves analysis indicates that ACT in patients with mild intermittent rhinitis is more reliable (AUC: 0.714; p < 0.05) than in patients with nasal polyposis/chronic rhino-sinusitis (AUC: 0.176; p > 0.05). Considering asthma classification, the probability that ACT detects patients with uncontrolled asthma is significantly higher in moderate persistent asthma subgroup than in mild persistent asthma one (OR 5.464; IC 95%: 2.5-11,9; p < 0.05). Conclusions: As ACT mainly relies on patient's reported outcomes, it may not completely reflect the airways inflammation and airways obstruction. The presence and severity of rhinitis may affect ACT outcome. The awareness of the variables that could influence ACT evaluation is much more important in the primary care setting where ACT may often represent the only tool for asthma assessment.

New Role of Adult Lung c-kit+ Cells in a Mouse Model of Airway Hyperresponsiveness.

Structural changes contribute to airway hyperresponsiveness and airflow obstruction in asthma. Emerging evidence points to the involvement of c-kit+ cells in lung homeostasis, although their potential role in asthma is unknown. Our aim was to isolate c-kit+ cells from normal mouse lungs and to test whether these cells can interfere with hallmarks of asthma in an animal model. Adult mouse GFP-tagged c-kit+ cells, intratracheally delivered in the ovalbumin-induced airway hyperresponsiveness, positively affected airway remodeling and improved airway function. In bronchoalveolar lavage fluid of cell-treated animals, a reduction in the number of inflammatory cells and in IL-4, IL-5, and IL-13 release, along with an increase of IL-10, was observed. In MSC-treated mice, the macrophage polarization to M2-like subset may explain, at least in part, the increment in the level of anti-inflammatory cytokine IL-10. After in vitro stimulation of c-kit+ cells with proinflammatory cytokines, the indoleamine 2,3-dioxygenase and TGFβ were upregulated. These data, together with the increased apoptosis of inflammatory cells in vivo, indicate that c-kit+ cells downregulate immune response in asthma by influencing local environment, possibly by cell-to-cell contact combined to paracrine action. In conclusion, intratracheally administered c-kit+ cells reduce inflammation, positively modulate airway remodeling, and improve function. These data document previously unrecognized properties of c-kit+ cells, able to impede pathophysiological features of experimental airway hyperresponsiveness.

The Role of Ion Channels to Regulate Airway Ciliary Beat Frequency During Allergic Inflammation.

Overproduction of mucus is a hallmark of asthma. The aim of this study was to identify potentially effective therapies for removing excess mucus. The role of voltage-gated (Kir 6.1, KCa 1.1) and store-operated ion channels (SOC, CRAC) in respiratory cilia, relating to the tracheal ciliary beat frequency (CBF), was compared under the physiological and allergic airway conditions. Ex vivo experiments were designed to test the local effects of Kir 6.1, KCa 1.1 and CRAC ion channel modulators in a concentration-dependent manner on the CBF. Cilia, obtained with the brushing method, were monitored by a high-speed video camera and analyzed with ciliary analysis software. In natural conditions, a Kir 6.1 opener accelerated CBF, while CRAC blocker slowed it in a concentration-dependent manner. In allergic inflammation, the effect of Kir 6.1 opener was insignificant, with a tendency to decrease CBF. A cilio-inhibitory effect of a CRAC blocker, while gently reduced by allergic inflammation, remained significant. A KCa 1.1 opener turned out to significantly enhance the CBF under the allergic OVA-sensitized conditions. We conclude that optimally attuned concentration of KCa 1.1 openers or special types of bimodal SOC channel blockers, potentially given by inhalation, might benefit asthma.

Plasma total thiol pool in children with asthma: Modulation during montelukast monotherapy

Inflammation, which is a hallmark of asthma, is one of the main sources of oxidative stress in the human body. Thiols are powerful antioxidants that protect cells against the consequences of oxidative stress. We aimed to investigate whether asthma and montelukast monotherapy affect the total plasma thiol pool in children. A total of 60 children with asthma and 35 healthy controls participated in the study. Group I consisted of newly diagnosed asthmatics who did not have regular anti-asthmatic therapy previously. Group II consisted of patients who had been undertaking montelukast monotherapy regularly for at least 4 months. Plasma total antioxidant status (TAS) and plasma total thiol (PTT) were measured using spectrophotometric methods. Bronchial asthma patients in both groups I and II had decreased median TAS levels compared with the control group (1.59 [interquartile range, 1.04-1.70] and 1.67 [1.50-1.75] vs. 2.98 [2.76-3.16] Trolox equiv./L, respectively; P<0.001). Group I had decreased PTT concentrations compared with the control group (0.18 [0.16-0.20] vs. 0.21 [0.19-0.22] mmol/L; P<0.001), and group II had similar PTT levels to the control group (0.20 [0.17-0.22] mmol/L; P>0.05). In addition, the median TAS and PTT levels for groups I and II were not statistically different (P>0.05). There was a positive correlation between TAS and PTT levels (rho=0.38, P<0.05) in group I. In order to balance the oxidative stress, both TAS and PTT which are markers of the antioxidant system are reduced in children with asthma. Montelukast monotherapy can limit oxidative stress and thus restore PTT levels but not TAS levels in asthmatic children.

Bronchoconstriction induced by inhaled methacholine delays desflurane uptake and elimination in a piglet model

Bronchoconstriction is a hallmark of asthma and impairs gas exchange. We hypothesized that pharmacokinetics of volatile anesthetics would be affected by bronchoconstriction. Ventilation/perfusion (VA/Q) ratios and pharmacokinetics of desflurane in both healthy state and during inhalational administration of methacholine (MCh) to double peak airway pressure were studied in a piglet model.In piglets, MCh administration by inhalation (100μg/ml, n=6) increased respiratory resistance, impaired VA/Q distribution, increased shunt, and decreased paO2 in all animals. The uptake and elimination of desflurane in arterial blood was delayed by nebulization of MCh, as determined by Micropore Membrane Inlet Mass Spectrometry (wash-in time to P50, healthy vs. inhalation: 0.5min vs. 1.1min, to P90: 4.0min vs. 14.8min). Volatile elimination was accordingly delayed.Inhaled methacholine induced severe bronchoconstriction and marked inhomogeneous VA/Q distribution in pigs, which is similar to findings in human asthma exacerbation. Furthermore, MCh-induced bronchoconstriction delayed both uptake and elimination of desflurane. These findings might be considered when administering inhalational anesthesia to asthmatic patients.

Bronchial hyperresponsiveness, airway inflammation, and reversibility in patients with chronic obstructive pulmonary disease.

BackgroundBronchial hyperresponsiveness (BHR), sputum eosinophilia, and bronchial reversibility are often thought to be a hallmark of asthma, yet it has been shown to occur in COPD as well.ObjectivesTo evaluate the relationship between BHR, lung function, and airway inflammation in COPD patients.MethodsThirty-one, steroid-free patients with stable, mild and moderate COPD were studied. The following tests were carried out: baseline lung function, reversibility, provocative dose of methacholine causing a 20% fall in forced expiratory volume in 1 second, a COPD symptom score, and sputum induction.ResultsTwenty-nine patients completed the procedures. About 41.4% had BHR, 31.0% had increased sputum eosinophils, and 37.9% had bronchial reversibility. Some of the patients had only one of these characteristics while others had two or the three of them. Patients with BHR had higher sputum eosinophils than patients without BHR (P=0.046) and those with sputum eosinophils ≥3% had more exacerbations in the previous year and a higher COPD symptom score than patients with sputum eosinophils <3% (P=0.019 and P=0.031, respectively). In patients with BHR, the cumulative dose of methacholine was negatively related to the symptom score and the number of exacerbations in the previous year. When patients with bronchial reversibility were considered, bronchodilation was positively related to sputum eosinophils.ConclusionOur study showed that BHR, sputum eosinophilia, and bronchial reversibility were not clustered in one single phenotype of COPD but could be present alone or together. Of interest, BHR and airway eosinophilia were associated with clinical data in terms of exacerbations and symptoms. Further investigation is needed to clarify this topic.

Monitoring asthma in childhood: lung function, bronchial responsiveness and inflammation.

This review focuses on the methods available for measuring reversible airways obstruction, bronchial hyperresponsiveness (BHR) and inflammation as hallmarks of asthma, and their role in monitoring children with asthma. Persistent bronchial obstruction may occur in asymptomatic children and is considered a risk factor for severe asthma episodes and is associated with poor asthma outcome. Annual measurement of forced expiratory volume in 1 s using office based spirometry is considered useful. Other lung function measurements including the assessment of BHR may be reserved for children with possible exercise limitations, poor symptom perception and those not responding to their current treatment or with atypical asthma symptoms, and performed on a higher specialty level. To date, for most methods of measuring lung function there are no proper randomised controlled or large longitudinal studies available to establish their role in asthma management in children. Noninvasive biomarkers for monitoring inflammation in children are available, for example the measurement of exhaled nitric oxide fraction, and the assessment of induced sputum cytology or inflammatory mediators in the exhaled breath condensate. However, their role and usefulness in routine clinical practice to monitor and guide therapy remains unclear, and therefore, their use should be reserved for selected cases.