Recombinant Slit2 attenuates tracheal fibroblast activation in benign central airway obstruction by inhibiting the TGF-β1/Smad3 signaling pathway

Airway fibrosis is among the pathological manifestations of benign central airway obstruction noted in the absence of effective treatments and requires new drug targets to be developed. Slit guidance ligand 2-roundabout guidance receptor 1 (Slit2-Robo1) is involved in fibrosis and organ development. However, its significance in airway fibrosis has not yet been reported. The study explored how the recombinant protein Slit2 functions in transforming growth factor-β1 (TGF-β1)-mediated airway fibrosis in vivo and in vitro. In this study, Slit2 expression initially increased in the tracheal granulation tissues of patients with tracheobronchial stenosis but decreased in the fibrotic tissue. In primary rat tracheal fibroblasts (RTFs), recombinant Slit2 inhibited the expression of extracellular matrices such as Timp1, α-SMA, and COL1A2, whereas recombinant TGF-β1 promoted the expression of Robo1, α-SMA, and COL1A2. Slit2 and TGF-β1 played a mutual inhibitory role in RTFs. Slit2 supplementation and Robo1 downregulation inhibited excessive extracellular matrix (ECM) deposition induced by TGF-β1 in RTFs via the TGF-β1/Smad3 pathway. Ultimately, exogenous Slit2 and Robo1 knockdown-mediated attenuation of airway fibrosis were validated in a trauma-induced rat airway obstruction model. These findings demonstrate that recombinant Slit2 alleviated pathologic tracheobronchial healing by attenuating excessive ECM deposition. Slit2-Robo1 is an attractive target for further exploring the mechanisms and treatment of benign central airway obstruction.

Evaluation of serum cytokine levels in recurrent airway obstruction

Recurrent airway obstruction (RAO) represents a serious health problem and is traditionally classified as an allergic disease, where contact with an antigen can induce clinical airway inflammation, bronchial hyper-responsiveness and reversible airway obstruction. Previous studies have demonstrated the presence of the Th2 response in the lungs of human patients with asthma and horses with heaves. These cells are involved in the production of cytokines which regulate the synthesis of immunoglobulins. 40 horses were evaluated: 30 horses with RAO and 10 healthy animals. The expression levels of interferon-alpha 1 (IFN-α1), interferon-gamma (IFN-γ), interleukin-1β, (IL-1β), IL-2, IL-4, IL-13 and tumor necrosis factor alpha (TNF-α) were measured in the serum obtained from control and RAO-susceptible horses during crisis. In all the patients, serum cytokine levels were detected. Serum median IL-13 and IFN-γ levels were significantly higher in RAO-affected horses than in the healthy group (p < 0.001). The serum median IFN-α1, IL-1β, IL-2, IL-4, and TNF-α levels were similar in both groups. These results indicate a low variability of the levels of cytokines and a high frequency of their detection in serum samples from horses with RAO. Immune mechanisms involved in equine RAO are more complex than those defined by a simple Th1/Th2 dichotomy.

Exercise-Induced Changes in Exhaled NO Differentiates Asthma With or Without Fixed Airway Obstruction From COPD With Dynamic Hyperinflation

Asthmatic patients with fixed airway obstruction (FAO) and patients with chronic obstructive pulmonary disease (COPD) share similarities in terms of irreversible pulmonary function impairment. Exhaled nitric oxide (eNO) has been documented as a marker of airway inflammation in asthma, but not in COPD. To examine whether the basal eNO level and the change after exercise may differentiate asthmatics with FAO from COPD, 27 normal subjects, 60 stable asthmatics, and 62 stable COPD patients were studied. Asthmatics with FAO (n = 29) were defined as showing a postbronchodilator FEV1/forced vital capacity (FVC) ≤70% and FEV1 less than 80% predicted after inhaled salbutamol (400 μg). COPD with dynamic hyperinflation (n = 31) was defined as a decrease in inspiratory capacity (ΔIC%) after a 6 minute walk test (6MWT). Basal levels of eNO were significantly higher in asthmatics and COPD patients compared to normal subjects. The changes in eNO after 6MWT were negatively correlated with the percent change in IC (r = -0.380, n = 29, P = 0.042) in asthmatics with FAO. Their levels of basal eNO correlated with the maximum mid-expiratory flow (MMEF % predicted) before and after 6MWT. In COPD patients with air-trapping, the percent change of eNO was positively correlated to ΔIC% (rs = 0.404, n = 31, P = 0.024). We conclude that asthma with FAO may represent residual inflammation in the airways, while dynamic hyperinflation in COPD may retain NO in the distal airspace. eNO changes after 6MWT may differentiate the subgroups of asthma or COPD patients and will help toward delivery of individualized therapy for airflow obstruction.

Airway factor XIII associates with type 2 inflammation and airway obstruction in asthmatic patients

BACKGROUND

Coagulation Factor XIII (FXIII) plays an important role in wound healing by stabilizing fibrin clots and cross-linking extracellular matrix proteins. FXIII is expressed in cells of the monocyte/macrophage and dendritic cell lineages in response to type 2 cytokines.

OBJECTIVE

We sought to determine the association between FXIII and asthma pathobiology.

METHODS

We analyzed the expression of FXIII mRNA and protein levels in bronchoalveolar lavage samples obtained before and after segmental allergen challenge from patients with mild asthma and in induced sputum samples collected from patients with mild-to-moderate and severe asthma.

RESULTS

FXIII mRNA and protein levels were highly upregulated in bronchoalveolar cells and fluid after allergen challenge and mRNA levels correlated with protein levels. In sputum of asthmatic patients, FXIII expression was positively correlated with type 2 immune response and dendritic cell markers (CD209 and CD207). FXIII expression was also associated with increased airflow limitation (FEV1/forced vital capacity and residual volume/total lung capacity ratios) and greater reversibility to β-agonists.

CONCLUSIONS

FXIII expression was upregulated in the airways of asthmatic patients after allergen exposure. Expression in the sputum of asthmatic patients correlated with the type 2 immune response and airflow limitation. Excessive activity of FXIII could contribute to the pathophysiology of airway obstruction in asthmatic patients.

Secretoglobin 1A1 and 1A1A differentially regulate neutrophil reactive oxygen species production, phagocytosis and extracellular trap formation

Secretoglobin family 1A member 1 (SCGB 1A1) is a small protein mainly secreted by mucosal epithelial cells of the lungs and uterus. SCGB 1A1, also known as club (Clara) cell secretory protein, represents a major constituent of airway surface fluid. The protein has anti-inflammatory properties, and its concentration is reduced in equine recurrent airway obstruction (RAO) and human asthma. RAO is characterized by reversible airway obstruction, bronchoconstriction and neutrophilic inflammation. Direct effects of SCGB 1A1 on neutrophil functions are unknown. We have recently identified that the SCGB1A1 gene is triplicated in equids and gives rise to two distinct proteins. In this study we produced the endogenously expressed forms of SCGBs (SCGB 1A1 and 1A1A) as recombinant proteins, and analyzed their effects on reactive oxygen species production, phagocytosis, chemotaxis and neutrophil extracellular trap (NET) formation ex vivo. We further evaluated whether NETs are present in vivo in control and inflamed lungs. Our data show that SCGB 1A1A but not SCGB 1A1 increase neutrophil oxidative burst and phagocytosis; and that both proteins markedly reduce neutrophil chemotaxis. SCGB 1A1A reduced chemotaxis significantly more than SCGB 1A1. NET formation was significantly reduced in a time- and concentration-dependent manner by SCGB 1A1 and 1A1A. SCGB mRNA in bronchial biopsies, and protein concentration in bronchoalveolar lavage fluid, was lower in horses with RAO. NETs were present in bronchoalveolar lavage fluid from horses with exacerbated RAO, but not in fluid from horses with RAO in remission or in challenged healthy horses. These findings indicate that SCGB 1A1 and 1A1A have overlapping and diverging functions. Considering disparities in the relative abundance of SCGB 1A1 and 1A1A in airway secretions of animals with RAO suggests that these functional differences may contribute to the pathogenesis of RAO and other neutrophilic inflammatory lung diseases.

RSV-encoded NS2 promotes epithelial cell shedding and distal airway obstruction

Respiratory syncytial virus (RSV) infection is the major cause of bronchiolitis in young children. The factors that contribute to the increased propensity of RSV-induced distal airway disease compared with other commonly encountered respiratory viruses remain unclear. Here, we identified the RSV-encoded nonstructural 2 (NS2) protein as a viral genetic determinant for initiating RSV-induced distal airway obstruction. Infection of human cartilaginous airway epithelium (HAE) and a hamster model of disease with recombinant respiratory viruses revealed that NS2 promotes shedding of infected epithelial cells, resulting in two consequences of virus infection. First, epithelial cell shedding accelerated the reduction of virus titers, presumably by clearing virus-infected cells from airway mucosa. Second, epithelial cells shedding into the narrow-diameter bronchiolar airway lumens resulted in rapid accumulation of detached, pleomorphic epithelial cells, leading to acute distal airway obstruction. Together, these data indicate that RSV infection of the airway epithelium, via the action of NS2, promotes epithelial cell shedding, which not only accelerates viral clearance but also contributes to acute obstruction of the distal airways. Our results identify RSV NS2 as a contributing factor for the enhanced propensity of RSV to cause severe airway disease in young children and suggest NS2 as a potential therapeutic target for reducing the severity of distal airway disease.

Critical role of TLR4 in human metapneumovirus mediated innate immune responses and disease pathogenesis

Human metapneumovirus (hMPV) is one of the main causes of acute respiratory tract infections in children, elderly and immunocompromised patients. The mammalian Toll-like receptors (TLR) were identified as critical regulators of innate immunity to a variety of microbes, including viruses. We have recently shown that hMPV-induced cytokine, chemokine and type I interferon secretion in dendritic cells occurs via TLR4, however, its role in hMPV-induced disease is unknown. In this study, wild-type(WT) and TLR4-deficient mice (TLR4^−/−) were infected with hMPV and examined for clinical disease parameters, such as body weight loss and airway obstruction, viral clearance, lung inflammation, dendritic cell maturation, T-cell proliferation and antibody production. Our results demonstrate that absence of TLR4 in hMPV-infected mice significantly reduced the inflammatory response as well as disease severity, shown by reduced body weight loss and airway obstruction and hyperresponsiveness (AHR), compared to WT mice. Levels of cytokines and chemokines were also significantly lower in the TLR4^−/− mice. Accordingly, recruitment of inflammatory cells in the BAL, lungs, as well as in lymph nodes, was significantly reduced in the TLR4^−/− mice, however, viral replication and clearance, as well as T-cell proliferation and neutralizing antibody production, were not affected. Our findings indicate that TLR4 is important for the activation of the innate immune response to hMPV, however it does play a role in disease pathogenesis, as lack of TLR4 expression is associated with reduced clinical manifestations of hMPV disease, without affecting viral protection.

CFTR regulates early pathogenesis of chronic obstructive lung disease in βENaC-overexpressing mice

Background

Factors determining the onset and severity of chronic obstructive pulmonary disease remain poorly understood. Previous studies demonstrated that airway surface dehydration in βENaC-overexpressing (βENaC-Tg) mice on a mixed genetic background caused either neonatal mortality or chronic obstructive lung disease suggesting that the onset of lung disease was modulated by the genetic background.

Methods

To test this hypothesis, we backcrossed βENaC-Tg mice onto two inbred strains (C57BL/6 and BALB/c) and studied effects of the genetic background on neonatal mortality, airway ion transport and airway morphology. Further, we crossed βENaC-Tg mice with CFTR-deficient mice to validate the role of CFTR in early lung disease.

Results

We demonstrate that the C57BL/6 background conferred increased CFTR-mediated Cl⁻ secretion, which was associated with decreased mucus plugging and mortality in neonatal βENaC-Tg C57BL/6 compared to βENaC-Tg BALB/c mice. Conversely, genetic deletion of CFTR increased early mucus obstruction and mortality in βENaC-Tg mice.

Conclusions

We conclude that a decrease or absence of CFTR function in airway epithelia aggravates the severity of early airway mucus obstruction and related mortality in βENaC-Tg mice. These results suggest that genetic or environmental factors that reduce CFTR activity may contribute to the onset and severity of chronic obstructive pulmonary disease and that CFTR may serve as a novel therapeutic target.

Analysis of polymorphisms in T(H)2-associated genes in Russian patients with atopic bronchial asthma

BACKGROUND

Bronchial asthma is a chronic respiratory disorder characterized by airway inflammation, airway hyperresponsiveness, and periodic reversible airway obstruction. Subtype 2 helperT cell (T(H)2) cytokines play an important role in the development of allergic airway inflammation in patients with bronchial asthma.

OBJECTIVE

To investigate whether the single-nucleotide polymorphisms (SNPs) Ile75Val and Gln576Arg in the IL4RA gene, -33C>T in the IL4 gene, and Gly237Glu in the FCER1B gene contribute to the development and severity of atopic bronchial asthma in Russian patients from Moscow.

METHODS

We analyzed DNA samples from 224 patients with atopic bronchial asthma and 172 healthy individuals. Genotyping was performed by primer extension followed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

RESULTS

We observed a moderate association between the Arg/Arg genotype of Gln576Arg and protection against asthma (odds ratio [OR], 0.16; P < .012) and a strong association between the T allele and TT genotype of -33C> and atopic bronchial asthma (OR, 1.91 and 4.65, respectively; P < .0001). Carriers of the C allele had a reduced risk of asthma (OR, 0.53; P < .0001). Furthermore, we found that the TT genotype of -33C>T correlated with higher concentrations of total serum immunoglobulin E and interleukin 4 than the CC and CT genotypes.

CONCLUSION

We found an association between atopic bronchial asthma and the SNPs Gln576Arg in IL4RA and -33C>T in IL4. IL4RA and IL4 seem to be involved in the pathogenesis of asthma.

Leukotriene receptors are differently expressed in fibroblast from peripheral versus central airways in asthmatics and healthy controls

Leukotrienes are involved in airway inflammation, and are believed to stimulate airway remodeling in asthma. The aim of the project was to investigate the expression of leukotriene receptors in peripheral and central airway fibroblasts. Peripheral and central airway fibroblasts, from asthmatics and healthy controls, were investigated for the amount of cysteinyl-leukotriene receptors (CysLT(1) and CysLT(2)), leukotriene B(4) receptors (BLT(1) and BLT(2)), IL-13 receptor-α(1) (IL-13Rα(1)) and the IL-4 receptor (IL-4R). The mRNA expression of CysLT(1) in fibroblasts from peripheral airways was higher compared to central airways. There was no difference in CysLT(2) between peripheral and central airways. On the contrary, BLT(1) and BLT(2) were lower in fibroblasts from peripheral airways compared to central. The expression of CysLT(1) was higher than CysLT(2) in fibroblasts from peripheral airways, and the expression of BLT(1) was higher than BLT(2) in both peripheral and central airways. Both BLT(1) and BLT(2) were higher in asthmatics compared to healthy controls, while CysLT(1) and CysLT(2) did not differ. The expression of IL-13Rα(1) was higher in asthmatics compared to controls, and correlated to the BLTs. All fibroblasts stained for the different receptor proteins. Leukotriene receptors are differently expressed in fibroblasts from peripheral compared to central airways, which may explain a suggested cysteinyl-leukotriene driven remodeling mainly in the peripheral airways.

Chronic inflammation in the cystic fibrosis lung: alterations in inter- and intracellular signaling

A vicious cycle of airway obstruction, infection, and inflammation continues to cause most of the morbidity and mortality in cystic fibrosis (CF). Mutations that result in decreased expression or function of the membrane Cl(-) channel, cystic fibrosis transmembrane regulator (CFTR), result in a decrease in the volume (and hence the depth) of liquid on the airway surface, impaired ciliary function, and dehydrated glandular secretions. In turn, these abnormalities contribute to a milieu, which promotes chronic infection with a limited but unique spectrum of microorganisms. Defects in CFTR also perturb regulation of several intracellular signaling pathways including signal transducers and activator of transcription, I-kappaB and nuclear factor-kappa B, and low molecular weight GTPases. Together, these abnormalities result in excessive production of NF-kappaB dependent cytokines such as interleukin (IL)-1, tumor necrosis factor (TNF), IL-6, and IL-8. There are decreased responses to interferon gamma and transforming growth factor beta leading to decreased production of iNOS and NO. Abnormalities of lipid mediators and decreased secretion of counter/regulatory cytokines have also been reported. Together, these effects combine to create a chronic inflammatory process, which damages and obstructs the airways, and eventually claims the life of the patient.

L-arginine attenuates acute lung injury after smoke inhalation and burn injury in sheep

Thermal injury results in reduced plasma levels of arginine (Arg). With reduced Arg availability, NOS produces superoxide instead of NO. We hypothesized that Arg supplementation after burn and smoke inhalation (B + S) injury would attenuate the acute insult to the lungs and, thus, protect pulmonary function. Seventeen Suffolk ewes (n = 17) were randomly divided into three groups: (1) sham injury group (n = 6), (2) B + S injury plus saline treatment (n = 6), and (3) B + S injury plus L-ARG infusion at 57 mg.kg(-1).h(-1) (n = 5). Burn and smoke inhalation injury was induced by standardized procedures, including a 40% area full thickness flame burn combined with 48 breaths of smoke from burning cottons. All animals were immediately resuscitated by Ringer solution and supported by mechanical ventilation for 48 h, during which various variables of pulmonary function were monitored. The results demonstrated that Arg treatment attenuated the decline of plasma Arg concentration after B + S injury. A higher plasma Arg concentration was associated with a less decline in Pao2/Fio2 ratio and a reduced extent of airway obstruction after B + S injury. Histopathological examinations also indicated a remarkably reduced histopathological scores associated with B + S injury. Nitrotyrosine stain in lung tissue was positive after B + S injury, but was significantly reduced in the group with Arg. Therefore, L-Arg supplementation improved gas exchange and pulmonary function in ovine after B + S injury via its, at least in part, effect on reduction of oxidative stress through the peroxynitrite pathway.

Equine recurrent airway obstruction does not alter airway muscarinic acetylcholine receptor expression and subtype distribution

In recurrent airway obstruction (RAO) or heaves, bronchospasm has been attributed to enhanced cholinergic activity. However, the expression and function of muscarinic acetylcholine receptors (mAChR) and their signaling components are not yet known. Thus, we examined the expression, subtype distribution and postreceptor signaling pathways of mAChR in the peripheral lung, bronchial and tracheal epithelia with the underlying smooth muscle from nine horses with RAO and 11 healthy control horses. In RAO horses, no significant segment-dependent alteration in mAChR density and subtype distribution (assessed by [N-methyl-3H]-scopolamine binding; ([3H]-NMS)), was found, except a trend in receptor down-regulation in some peripheral parts of the lung. The total number of high mAChR binding sites (assessed by carbachol-displacement experiments in the presence or absence of guanosine 5'-triphosphate) was not changed in RAO, suggesting that the functional coupling of mAChR to the corresponding G-proteins is intact. The M2-mediated inhibition of adenylate cyclase (AC) as well as the M3-receptor-G(q/11)-phospholipase C (PLC) activity was not different between RAO and control airway tissues. In conclusion, in equine RAO airways, mAChR expression and function were not altered, and thus appear not to account for the enhanced cholinergic activity in RAO.

Rat model of chronic recurrent airway obstructions to study the sleep apnea syndrome

STUDY OBJECTIVES

To implement a chronic rat model of recurrent airway obstructions to study the obstructive sleep apnea (OSA) syndrome.

DESIGN

Prospective controlled animal study.

SETTING

University laboratory.

PATIENTS OR PARTICIPANTS

24 male Sprague-Dawley rats (250-300 g).

INTERVENTIONS

The rats were placed in a setup consisting of a body chamber and a head chamber separated by a neck collar specially designed to apply recurrent airway obstructions with OSA patterns. Rats in the Obstruction group (n=8) were subjected to 5-s obstructions at a rate of 60 per hour, 6 h/day during 4 weeks. Sham rats (n=8) were placed in the setup but no obstructions were applied. Naive rats (n=8) were subjected to no intervention.

MEASUREMENTS AND RESULTS

Breathing flow, pressure, CO2 air concentration, and SpO2 showed that the model mimicked OSA respiratory events (obstructive apneas, increased respiratory efforts, and oxygen saturation dips). Animal stress, assessed by body weight and plasma corticosterone, was not significantly different across Obstruction and Sham groups. This supports the concept that this novel model does not introduce a significant burden of stress in the rat after acclimatization to the chamber. Thromboxane-B2/6-keto-Prostaglandin-Flalpha ratio in plasma, which is an index of vasoconstriction, was significantly increased in the rats subjected to obstructions.

CONCLUSIONS

The designed animal model of chronic recurrent airway obstructions is feasible and potentially useful to study the mechanisms involved in the cardiovascular consequences of OSA.

Endtidal carbon dioxide monitoring in children with congenital heart disease during sedation for cardiac catheterization by nonanesthesiologists

BACKGROUND

This prospective observational study compared endtidal carbon dioxide (P(E)CO(2)) with blood gas carbon dioxide (PaCO(2)) values in children sedated by nonanesthesiologists for cardiac catheterization.

METHODS

A nasal cannula designed to obtain gas sampling simultaneously from over the mouth and nares was taped into place after assuring a good waveform. Patients' cardiac lesions, site of blood gas sampling and P(E)CO(2)were recorded.

RESULTS

Two hundred and one blood/P(E)CO(2) pairs were measured in 59 patients from 4 days to 18 years of age. Linear regression, Pearson correlation, and Bland-Altman analysis revealed a reasonable relationship (r = 0.493, P < 0.01, bivariate Pearson correlation) for all blood/expired CO(2) pairs even when the blood sample was obtained from an area of the circulation with shunting. There was no significant difference in the accuracy of the blood/P(E)CO(2) pairs between infants who weighed </=15 kg compared with children who weighed >15 kg. Thirteen children were diagnosed with partial or complete airway obstruction.

CONCLUSIONS

Endtidal CO(2) measurement provides a reasonable reflection of blood CO(2) values if the expired gas-sampling catheter is taped in place after assuring a good waveform. The veracity of the data was the same throughout the patient size range. Expired CO(2) monitoring is useful for assessing the adequacy of respirations and the patency of the airway in children 3-89 kg.

Exhaled nitric oxide measurement in workers in a microwave popcorn production plant

Airways obstruction in microwave-popcorn workers has been attributed to inhalation of flavoring agents. Two former workers at a microwave-popcorn plant were found by lung biopsy to have bronchiolitis obliterans. The study's aim was to determine whether exhaled nitric oxide (FENO) levels were associated with exposure levels, respiratory symptoms, or airways obstruction. A questionnaire, spirometry, and FENO measurements were completed by 135 workers. The FENO levels of workers with high flavoring exposures (n = 107) were compared with those of workers with low exposures (n = 28) and healthy external controls (n = 31). FENO levels were significantly lower in the high-exposure group (p < 0.05). There is no indication that FENO is useful as a marker of lung injury in a flavoring-exposed worker population with a substantial lung disease burden, but the finding of low FENO in the high-exposure group should not be dismissed.

Changes in the levels of interferon-gamma and transforming growth factor-beta influence bronchial stenosis during the treatment of endobronchial tuberculosis

BACKGROUND

Endobronchial tuberculosis (EBTB) has been shown to frequently complicate bronchial stenosis, a condition which can induce dyspnea as a result of airway obstruction, and is also frequently misdiagnosed as either bronchial asthma or lung cancer.

OBJECTIVES

This study attempted to determine whether there was a correlation between interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) levels in the serum and bronchial washing fluid (BWF), and the results of the treatment of EBTB patients.

METHODS

Thirty patients, all of whom were diagnosed as EBTB, were enrolled, as were 10 healthy control subjects. IFN-gamma and TGF-beta levels were measured by the ELISA method in the serum and BWF of these 30 EBTB patients before and after treatment. The EBTB patients were divided into two groups: those who exhibited bronchial stenosis after treatment and those who did not. Chest computed tomography (CT) and pulmonary function test (PFT) were performed in 16 and 25 patients, respectively, at initial bronchoscopy.

RESULTS

IFN-gamma and TGF-beta levels in the BWF of the EBTB patients were elevated compared to the controls (p < 0.05). After 2 months of treatment, 13 of the 30 EBTB patients exhibited bronchial fibrostenosis and the other 17 cases had recovered without sequelae. In the bronchial stenosis group, the initial serum TGF-beta levels were lower than in the patients without bronchial stenosis (p < 0.05). Moreover, the levels of serum TGF-beta after treatment were shown to have decreased more than in the patients without bronchial stenosis (p < 0.05). On chest CT findings of 16 EBTB patients, bronchial narrowing was suspected except in 2 cases (1 edematous-hyperemic type, 1 actively caseating type of segmental bronchus). The common features of PFT in EBTB at the initial diagnosis were a restrictive pattern and normal ventilatory function.

CONCLUSIONS

Elevated IFN-gamma and TGF-beta levels in the BWF of the EBTB patients may be related to EBTB pathogenesis. Lowered initial serum TGF-beta levels as well as the observed changes in the levels of TGF-beta in the serum after treatment have been implicated in bronchial fibrostenosis during the course of the disease.

Inhibition of mucin secretion with MARCKS-related peptide improves airway obstruction in a mouse model of asthma

Allergic asthma is associated with airway epithelial cell mucous metaplasia and mucin hypersecretion, but the consequences of mucin hypersecretion on airway function are unclear. Recently, a peptide derived from the myristoylated alanine-rich C kinase substrate protein NH(2)-terminal sequence (MANS) was shown to inhibit methacholine (MCh)-induced mucin secretion from airway mucous cells by >90%. We studied the effect of intranasal pretreatment with this peptide on specific airway conductance (sGaw) during challenge with MCh in mice with allergen-induced mucous cell metaplasia. sGaw was noninvasively measured in spontaneously breathing restrained mice, using a double-chamber plethysmograph. Pretreatment with MANS peptide, but not a control peptide [random NH(2)-terminal sequence (RNS)], resulted in partial inhibition of the fall in sGaw induced by 60 mM MCh (mean +/- SE; baseline 1.15 +/- 0.06; MANS/MCh 0.82 +/- 0.05; RNS/MCh 0.55 +/- 0.05 cmH(2)O/s). The protective effect of MANS was also seen in mice challenged with allergen for 3 consecutive days to increase airway hyperresponsiveness, although the degree of protection was less (baseline 1.1 +/- 0.08; MANS/MCh, 0.65 +/- 0.06; RNS/MCh 0.47 +/- 0.03 cmH(2)O/s). Because routine sGaw measurement in mice includes nasal airways, the effectiveness of MANS was also confirmed in mice breathing through their mouths after nasal occlusion (baseline 0.92 +/- 0.05; MANS/MCh 0.83 +/- 0.06; RNS/MCh 0.61 +/- 0.03 cmH(2)O/s). In all instances, sGaw in the MANS-pretreated group was approximately 35% higher than in RNS-treated controls, and mucous obstruction accounted for approximately 50% of the MCh-induced fall in sGaw. In summary, mucin secretion has a significant role in airway obstruction in a mouse model of allergic asthma, and strategies to inhibit mucin secretion merit further investigation.

The metabolic syndrome in patients with chronic obstructive pulmonary disease

PURPOSE

This study was undertaken to evaluate the presence of the metabolic syndrome in COPD patients who participated in a cardiopulmonary rehabilitation program. The metabolic syndrome is characterized by the presence of abdominal obesity, atherogenic dyslipidemia, raised blood pressure, presence of insulin resistance, and prothrombotic and inflammatory states that predispose to cardiovascular diseases.

METHODS

Thirty-eight COPD patients (age: 66 +/- 7 years, [mean +/- SD], FEV1: 43 +/- 16% predicted) and 34 control participants matched for age and gender are included in this study. The criteria for the identification of the metabolic syndrome include 3 or more of the following features: abdominal obesity (waist circumference: > 102 cm in men, > 88 cm in women), triglycerides levels (>or= 1.69 mmol/L), high-density lipoprotein cholesterol levels (< 1.0 mmol/L in men, < 1.3 mmol/L in women), blood pressure (>or= 130/ >or= 85 mm Hg), and fasting glucose levels (>or= 6.1 mmol/L).

RESULTS

Forty-seven percent of COPD patients and 21% of control participants presented 3 or more determinants of the metabolic syndrome.

CONCLUSIONS

The presence of metabolic syndrome is frequent in patients with COPD who participated in a cardiopulmonary program. Hence, this population should be considered for screening for the metabolic syndrome.

Increased serum levels of chromogranin A in male smokers with airway obstruction

The neuroendocrine (NE) system may play an important role in smoking-induced airway diseases. The aim of the present study was to examine the relationship between serum levels of the general NE marker chromogranin A (CgA) and smoking habits, respiratory symptoms and lung function. The study population consisted of never-smokers with normal lung function, smokers with normal lung function and smokers with airway obstruction who were randomly selected from the lung study of the Nord-Trøndelag Health Study (HUNT). Serum CgA was determined in 151, 138 and 116 subjects, respectively. All subjects were seronegative for Helicobacter pylori. Male smokers with airway obstruction had significantly higher serum CgA levels (median 3.70 nmol x L(-1) (interquartile range 3.10-5.15)) than both smokers with normal lung function (3.00 nmol x L(-1) (2.50-3.67)) and never-smokers with normal lung function (2.90 nmol x L(-1) (2.57-3.30)). The elevated levels of CgA correlated with the degree of airway obstruction. Moreover, the presence of respiratory symptoms and chronic bronchitis among male smokers were associated with increased serum CgA levels. Females had CgA levels similar to male smokers independent of smoking status and lung function. Elevated serum chromogranin A levels in subjects with airway obstruction and respiratory symptoms may represent neuroendocrine activation in inflammatory or remodelling processes in the lung.

Positive interaction of the novel beta2-agonist carmoterol and tiotropium bromide in the control of airway changes induced by different challenges in guinea-pigs

This study evaluated the bronchodilating activity of the beta(2)-agonist carmoterol and the muscarinic M(3)-antagonist tiotropium, given intratracheally alone or in combination in anaesthetized artificially ventilated normal and actively sensitized guinea-pigs. Carmoterol (0.3-100pmol) and tiotropium (10-1000pmol) were superfused (0.01ml/min) for 5min before challenges with acetylcholine (20mug/kg i.v.), histamine (10mug/kg i.v.) or ovalbumin (5mg/kg i.v.). Both compounds given alone were markedly active against all the challenges. Tiotropium resulted more effective towards cholinergic challenge and carmoterol was very potent against histamine and ovalbumin-induced reaction, being effective already at 1pmol. In the presence of tiotropium, the bronchodilating activity of carmoterol was significantly augmented. The ED(50) value of carmoterol on the acetylcholine challenge was reduced by about 10 and 28 times (0.1 and 0.3pmol of tiotropium), that on the histamine one by 4.5 and 13 times (1 and 3pmol of tiotropium) and that on the ovalbumin-induced one by 8 and 25 times (10 and 30pmol of tiotropium). A positive interaction was also evident when other parameters were evaluated. The histamine-induced release of thromboxane B(2) was markedly reduced (56%, P<0.001) by combining completely ineffective doses of the two drugs (0.3 and 3pmol for carmoterol and tiotropium, respectively). In ovalbumin-challenged animals the time to death, amounting in control animals to 7.2+/-0.9min, was dose-dependently prolonged up to achieve complete protection from death with combination of 1 and 30pmol of carmoterol and tiotropium, respectively. The favorable interaction between carmoterol and tiotropium can represent a good option in the control of bronchopulmonary diseases marked by an increase of airway resistances.

An inverse relationship between peroxisome proliferator-activated receptor gamma and allergic airway inflammation in an allergen challenge model

BACKGROUND

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) expression has not been evaluated in bronchoalveolar lavage (BAL) cells from allergic asthmatic patients.

OBJECTIVE

To determine whether inappropriate down-regulation of PPAR-gamma in alveolar macrophages may contribute to persistent airway inflammation in allergic asthma.

METHODS

We used segmental allergen challenge as a model of in vivo experimental allergic asthmatic exacerbation and airway inflammation. PPAR-y gene expression was evaluated at baseline and 24 hours later in asthmatic patients and controls using real-time polymerase chain reaction. Immunofluorescence was used to determine cellular location of the PPAR-gamma protein.

RESULTS

We demonstrate for the first time to our knowledge that PPAR-gamma messenger RNA and protein, which are highly expressed in alveolar macrophages of healthy individuals, are significantly reduced in asthmatic patients after segmental allergen challenge. In allergic asthmatic patients (n=9), PPAR-gamma gene expression decreased significantly from baseline to postchallenge BAL (median decrease, 45%; P = .008). Furthermore, immunofluorescence staining demonstrated that PPAR-gamma protein was associated with alveolar macrophages and not with inflammatory eosinophils and neutrophils.

CONCLUSION

Results implicate down-regulation of PPAR-gamma in BAL cells as a potential factor in dysregulation of lung homeostasis in asthmatic patients. The present findings suggest that PPAR-gamma agonists could have a future role in asthma therapy and warrant further study.

Effects of changes to the stable environment on the exhalation of ethane, carbon monoxide and hydrogen peroxide by horses with respiratory inflammation

The aim of this study was to assess the effects of changes to the stable environment on exhaled markers of respiratory inflammation in six horses with clinical histories of recurrent airway obstruction. The horses were maintained for two weeks under conventional stable management (straw bedding and hay) and for two weeks on a reduced-dust regimen (paper bedding and ensiled grass), in a crossover study design. Exhaled ethane and carbon monoxide (CO) and exhaled breath condensate hydrogen peroxide (H(2)O(2)) were measured every three days under each regimen. The presence of clinical signs of airway inflammation (nasal discharge and cough) was monitored daily. The reduced-dust regimen was associated with fewer clinical signs of airway inflammation than the conventional regimen. Exhaled ethane and CO were significantly lower on the reduced-dust regimen and these markers were correlated with clinical signs of respiratory inflammation, but exhaled H(2)O(2) was not affected by the management regimen.

Obstructive sleep apnea syndrome: a potential cause of lower airway obstruction in cystic fibrosis

A six-year-old healthy female with cystic fibrosis (CF) and pancreatic sufficiency presented with cough, weight loss, and lung function decline. Further history suggested obstructive sleep apnea, and nocturnal polysomnography (NPSG) confirmed this. Adenotonsillectomy resulted in resolution of clinical symptoms with return of normal lung function. This case establishes that obstructive sleep apnea syndrome (OSAS) may be a potential cause of lower airway inflammation and resulting weight loss in the young CF population.

Airway clearance in bronchiectasis: a randomized crossover trial of active cycle of breathing techniques versus Acapella

BACKGROUND

The efficacy of a new airway clearance device (Acapella) has not been previously investigated. Active cycle of breathing techniques (ACBT) is the standard airway clearance technique used in patients with bronchiectasis.

OBJECTIVE

The objective of this study was to compare the efficacy of ACBT with Acapella as methods of airway clearance in adults with stable, productive bronchiectasis.

METHODS

Twenty patients (7 males), age 58 +/- 11 years (mean +/- SD), FEV1 64 +/- 22% predicted with stable (change of not greater than FEV1 10% predicted during 3 months prior to study), productive (history of expectoration of half an egg cup sputum/day) bronchiectasis attended the respiratory clinic on 3 days. Day 1: 40-min training session on ACBT and Acapella. Days 2 and 3: 30-min treatment session of either ACBT or Acapella. Treatment order was determined by a concealed randomization procedure. The following outcomes were measured before and after treatment spirometry, SpO2 and breathlessness by an independent assessor who was blinded to treatment order. Weight of sputum (during treatment plus 30 min after treatment), number of coughs and patient preference were also recorded.

RESULTS

No significant differences were found at baseline indicating that patients were stable. No significant differences were found between weight of sputum expectorated with ACBT treatment and weight of sputum expectorated with Acapella treatment--mean difference 0.54 g (95% CI -0.39 to 1.46). A greater proportion of patients preferred Acapella (14/20).

CONCLUSION

Acapella is as effective a method of airway clearance as ACBT and may offer a user-friendly alternative to ACBT for patients with bronchiectasis.

Agonist-independent alteration in beta-adrenoceptor-G-protein-adenylate cyclase system in an equine model of recurrent airway obstruction

We examined the inhibitory sympathetic beta-adrenergic mechanisms in peripheral lung, bronchi and trachea of an equine model of recurrent airway obstruction (RAO), to support the hypothesis that the beta-adrenergic receptor dysfunction is not only restricted to cell surface receptor density but rather encompasses a mechanistic defect apart from the receptor, to the intracellular signaling components. The non-asthmatic lung possessed 3.2-fold more beta-adrenergic receptors than bronchi (496 +/- 19.4 vs. 155.1+/- 19.6 fmol/mg protein; P < 0.01) and 6.2-fold higher than in the trachea (79.8 +/- 12.6 fmol/mg protein; P < 0.001) (assessed by radioligand binding assays using (-)-[(125)I]-iodocyanopindolol, ICYP) and in all tissues a greater proportion of the beta(2)- than the beta(1)-subtype (75-80%). The receptor density (B(max)) in lung parenchyma and bronchial membranes was 33 and 42%, respectively, lower (P < 0.001) in RAO than in control animals, attributable to a decrease in the beta(2)-subtype. This receptor down-regulation was accompanied with an attenuated coupling efficiency of the receptor to the stimulatory G(S)-protein (P < 0.05 vs. control). Concomitantly, activation of adenylate cyclase evoked by isoproterenol was significantly reduced in lung and bronchial membranes of animals with RAO, whereas effects of 10 microM GTP, 10mM NaF, 10 microM forskolin and 10 mM Mn(2+) were not altered. There was no difference in beta-adrenergic receptor density, G(S)-protein or adenylate cyclase coupling in the trachea between asthmatic and control animals. In conclusion, in stable asthma the pulmonary beta-adrenergic receptor-G(S)-protein-adenylate cyclase system is impaired, thus the pathologic process involves all signaling components, and due to its close similarity, this animal model seems to serve as a suitable model, at least partly, of chronic asthmatic patients.

Congenital diaphragmatic hernia, tracheal occlusion, thyroid transcription factor-1, and fetal pulmonary epithelial maturation

Congenital diaphragmatic hernia (CDH) occurs in ∼1:2,500 human births and has high morbidity and mortality rates, primarily due to pulmonary hypoplasia and pulmonary hypertension. Tracheal occlusion (TO), in experimental animals, distends lungs and increases lung growth and alveolar type I cell maturation but decreases surfactant components and reduces alveolar type II cell density. We examined effects of CDH and CDH+TO on lung growth and maturation in fetal rats. To induce CDH, we administered nitrofen (100 mg) to dams at 9.5 days of gestation. We compared lungs from fetuses with CDH, CDH+TO, and those exposed to nitrofen without CDH. CDH decreased lung wet weight bilaterally ( P < 0.0001) and DNA content in lung ipsilateral to CDH ( P < 0.05). CDH+TO significantly increased lung wet weights bilaterally; DNA content was intermediate between CDH and NC. To evaluate effects on the distal pulmonary epithelium, we examined surfactant mRNA and protein levels, type I and II cell-specific markers (RTI40 and RTII70, respectively), and transcriptional regulator thyroid transcription factor-1 (TTF-1). Decreased lung distension (due to CDH) increased SP-C mRNA and TTF-1 protein expression and reduced RTI40 ( P < 0.05 for all). Increased lung distension (due to CDH+TO) reduced expression of SP mRNAs and pro-SP-C and TTF-1 proteins and enhanced expression of RTI40 (mRNA and protein; P < 0.05 for all). We conclude that CDH+TO partially reverses effects of CDH; it corrects the pulmonary hypoplasia and restores type I cell differentiation but adversely affects SP expression in type II cells. These effects may be mediated through changes in TTF-1 expression.

Overexpression of eCLCA1 in small airways of horses with recurrent airway obstruction

The human hCLCA1 and murine mCLCA3 (chloride channels, calcium-activated) have recently been identified as promising therapeutic targets in asthma. Recurrent airway obstruction in horses is an important animal model of human asthma. Here, we have cloned and characterized the first equine CLCA family member, eCLCA1. The 913 amino acids eCLCA1 polypeptide forms a 120-kDa transmembrane glycoprotein that is processed to an 80-kDa protein in vivo. Three single nucleotide polymorphisms were detected in the eCLCA1 coding region in 14 horses, resulting in two amino acid changes (485H/R and 490V/L). However, no functional differences were recorded between the channel properties of the two variants in transfected HEK293 cells. The eCLCA1 protein was detected immunohistochemically in mucin-producing cells in the respiratory and intestinal tracts, cutaneous sweat glands, and renal mucous glands. Strong overexpression of eCLCA1 was observed in the airways of horses with recurrent airway obstruction using Northern blot hybridization, Western blotting, immunohistochemistry, and real-time quantitative RT-PCR. The results suggest that spontaneous or experimental recurrent airway obstruction in horses may serve as a model to study the role of CLCA homologs in chronic airway disease with overproduction of mucins.

Inhibition of obliterative airway disease development in murine tracheal allografts by matrix metalloproteinase-9 deficiency

This study was designed to define the roles of matrix metalloproteinase (MMP)-2 and MMP-9 in obliterative airway disease (OAD) in heterotopic murine tracheal allografts, considered a suitable animal model for chronic lung allograft rejection. BALB/c tracheal allografts were transplanted into MMP-2-deficient (-/-) and MMP-9-/- mice. Also, wild-type recipients were treated with doxycycline, a nonspecific MMP inhibitor. After 10, 20 and 30 days, allografts were analyzed for OAD development, intragraft levels of MMP-2 and MMP-9 and the frequency and cytokine/chemokine production profile of alloreactive T cells. Allografts transplanted into wild-type mice developed OAD lesions within 30 days. These allografts revealed significant upregulation of both MMP-2 and MMP-9. Allografts transplanted into MMP-9-/- and doxycycline-treated recipients did not develop OAD. In contrast, allografts transplanted into MMP-2-/- mice developed OAD lesions with normal kinetics. Interestingly, MMP-9-/- recipients showed an enhanced T cell alloreactivity associated with an abnormal profile of cytokine/chemokine production. The enhanced T cell alloreactivity in MMP-9-/- mice was mediated by enhanced dendritic cell stimulatory capacity as well as enhanced T cell responsive capacity. These results suggest that MMP-9 plays an important role in the pathogenesis of OAD and may represent a target for the therapeutic intervention of chronic lung allograft rejection.

Chronic resistive airway loading reduces weight due to low serum IGF-1 in rats

One of the consequences of chronic resistive airway loading in rats is malfunction in body weight gain post-surgery. The lower body weight of the obstructed animals was not related to lower caloric intake or to the oxygen consumption/food intake ratio. In the current study, we determined whether the retardation in body weight gain was related to impairment of serum insulin-like growth factor-1 (IGF-1) level or due to activation of inflammatory factors 21 weeks post-surgery. During the observation period, the airway-loaded animals (n=8) gained 44% less body weight (P<0.001) compared with controls (n=8) with no apparent effect on skeletal growth, i.e., body, tail and tibia length. Chronic airway-loaded animals had 32.5% lower serum IGF-1 levels (P<0.001) compared to the controls. Interleukin-6 and tumor necrosis factor-alpha levels were below 30 pg/ml in both groups. These data suggest that the weight loss in the chronic airway-loading rats is associated with a decreased IGF-1 level and not to activation of the inflammatory response.

Mycoplasma pneumoniae induces host-dependent pulmonary inflammation and airway obstruction in mice

Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is a common etiologic agent of acute respiratory infection in children and adults that has been associated with wheezing in 20-40% of individuals. The current study was undertaken to elucidate the host-dependent pulmonary and immunologic response to M. pneumoniae respiratory infection by studying mice with different immunogenetic backgrounds (BALB/c mice versus C57BL/6 mice). After M. pneumoniae infection, only BALB/c mice developed significant airway obstruction (AO) compared with controls. M. pneumoniae-infected BALB/c mice manifested significantly elevated airway hyperresponsiveness (AHR) compared with C57BL/6 mice 4 and 7 d after inoculation as well as BALB/c control mice. Compared with C57BL/6 mice, BALB/c mice developed worse pulmonary inflammation, including greater peribronchial infiltrates. Infected BALB/c mice had significantly higher concentrations of tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-1beta, IL-6, IL-12, KC (functional IL-8), and macrophage inflammatory protein 1alpha in the bronchoalveolar lavage fluid compared with infected C57BL/6 mice. No differences in IL-2, IL-4, IL-5, IL-10, and granulocyte/macrophage colony-stimulating factor concentrations were found. The mice in this study exhibited host-dependent infection-related AO and AHR associated with chemokine and T-helper type (Th)1 pulmonary host response and not Th2 response after M. pneumoniae infection.

Extracellular matrix modulates beta2-adrenergic receptor signaling in human airway smooth muscle cells

The airways of patients with chronic asthma commonly develop an element of fixed airway obstruction, which fails to reverse with inhaled beta2-adrenoceptor agonists. Airway remodeling refers to the structural changes of the bronchi in longstanding asthma and is characterized by increased deposition and altered ratios of extracellular matrix (ECM) proteins. We therefore assessed whether ECM proteins alter beta2-adrenoceptor signaling in human airway smooth muscle cells. We report that a fibronectin environment increases responses to beta2-adrenoceptor stimulation, whereas exposure to collagen V or laminin decreases accumulation of the second messenger cyclic AMP when compared with collagens I or IV. These differences are likely to be physiologically significant as they translate into altered phosphorylation of the downstream target VASP. The altered cAMP levels are due to differences in adenylyl cyclase activity, although expression of the relevant isoforms of enzyme appears unaltered. However, inhibition of Galphai abrogates the differences in beta2-adrenoceptor-mediated cAMP accumulation in cells exposed to different matrix factors. The difference in Galphai signaling is not due to altered Galphai expression. We conclude therefore that ECM modulates Galphai activity in human airway smooth muscle cells, and propose that these changes could contribute to the fixed airway obstruction seen in patients with chronic asthma.

Role of endogenous endothelin-1 in transplant obliterative airway disease in the rat

Endothelin-1 (ET-1) expression is increased after lung transplantation in association with ischemia reperfusion injury and acute rejection. However, little is known of the role of ET-1 during the development of obliterative bronchiolitis. In this study, we investigated the biological significance of ET-1 in obliterative airway disease development using a rat tracheal allograft model. Immunoreactivity of ET-1 and its receptors ET-RA and ET-RB was increased four-fold in allografts compared with syngrafts and localized to mononuclear cells and smooth muscle cells of the myofibroproliferative lesion and airway wall, indicating that ET-1 may mediate its effects in both a paracrine and autocrine manner in smooth muscle cells. Inhibition of ET-1 action by a nonselective ET-1 receptor antagonist, bosentan, significantly decreased tracheal occlusion, which was linked to delayed epithelial necrosis, suppressed smooth muscle cell proliferation, and a marked reduction in the number of interleukin-1beta and interleukin-2 immunoreactive cells. Our findings show that endogenous ET-1 activation is associated with obliteration of the airway wall, and blocking signaling downstream of ET-1 receptors leads to attenuation of obliterative airway disease. The results suggest that ET-1 has a proproliferative and proinflammatory role in the development of obliterative bronchiolitis.

Airway glycoprotein secretion parallels production and predicts airway obstruction in pulmonary allergy

BACKGROUND

Airway obstruction, perhaps the most relevant clinical feature of asthma, is typically assessed in allergic asthma models as airway hyperresponsiveness. Excess secretion of airway glycoproteins also contributes to airway obstruction in asthma but is not measured as part of most experimental models.

OBJECTIVE

The purposes of this study were to develop a reliable, quantitative assay for detecting secreted airway glycoproteins and to assess the secretion of airway glycoproteins in comparison with other markers of airway obstruction resulting from allergic lung inflammation.

METHODS

Two microtiter plate-based glycoprotein-detecting methods were developed, one using an antiglycoprotein antibody and the other using the glycoprotein-binding plant lectin, jacalin. Both methods were used to assess airway glycoprotein secretion in response to 2 defined agonists given intranasally, IL-13 and an allergen derived from Aspergillus fumigatus. Glycoprotein secretion was assessed concomitant with another measure of airway obstruction, airway hyperresponsiveness provoked by acetylcholine challenge, and a histologic method for quantitating glycoprotein production.

RESULTS

Both assays were sufficient for quantitating airway glycoproteins over the full range of values encountered from murine bronchoalveolar lavage and yielded highly reproducible data. Secretion of airway glycoproteins increased commensurate with the detection of both airway hyperresponsiveness and airway glycoprotein production induced by IL-13 and allergen.

CONCLUSION

Airway glycoprotein secretion is a consistent feature of the allergic lung phenotype and likely contributes to airway obstruction induced by allergen in both humans and rodents.

Neurotrophins and neurotrophin receptors in allergic asthma

The neurotrophins nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 (NT-3) and NT-4 play a pivotal role in the development of the nervous system. Despite their well-known effects on neurons, elevated neurotrophin concentrations have been observed under pathological conditions in sera of patients with inflammatory disorders. Patients with asthma feature both airway inflammation and an abnormal airway reactivity to many unspecific stimuli, referred to as airway hyperresponsiveness, which is, at least partly, neuronally controlled. Interestingly, these patients show increased levels of neurotrophins in the blood as well as locally in the lung. It has been demonstrated that neurotrophin release from immune cells is triggered by allergen contact. The presence of neurotrophins and the neurotrophin receptors p75 (p75NTR), tyrosine kinase A (TrkA), TrkB and TrkC have been described in several immune cells. There is strong evidence for an involvement of neurotrophins in regulation of hematopoiesis and, in addition, in modulation of immune cell function in mature cells circulating in blood or resting in lymphatic organs and peripheral tissues. The aim of this review is to demonstrate possible roles of neurotrophins during an allergic reaction in consideration of the temporospatial compartimentalization.

Relationship between surface tension of upper airway lining liquid and upper airway collapsibility during sleep in obstructive sleep apnea hypopnea syndrome

Lowering surface tension (gamma) of upper airway lining liquid (UAL) reduces upper airway opening (anesthetized humans) and closing (anesthetized rabbits) pressures. We now hypothesize that in sleeping obstructive sleep apnea hypopnea syndrome (OSAHS) patients lowering gamma of UAL will enhance upper airway stability and decrease the severity of sleep-disordered breathing. Nine OSAHS patients [respiratory disturbance index (RDI): 49 +/- 8 (SE) events/h, diagnostic night] participated in a two-part, one-night, polysomnography study. In the first part, upper airway closing pressures (during non-rapid eye movement sleep, Pcrit) were measured and samples of UAL (awake) were obtained before and after 2.5 ml of surfactant (Exosurf, Glaxo Smith Kline) was instilled into the posterior pharynx. The gamma of UAL was determined with the use of the "pull-off" force technique. In the second part, subjects received a second application of 2.5 ml of surfactant and then slept the remainder of the night (205 +/- 30 min). Instillation of surfactant decreased the gamma of UAL from 60.9 +/- 3.1 mN/m (control) to 45.2 +/- 2.5 mN/m (surfactant group) (n = 9, P < 0.001). Pcrit decreased from 1.19 +/- 1.14 cmH2O (control) to -0.56 +/- 1.15 cmH2O (surfactant group) (n = 7, P < 0.02). Compared with the second half of diagnostic night, surfactant decreased RDI from 51 +/- 8 to 35 +/- 8 events/h (n = 9, P < 0.03). The fall in RDI (deltaRDI) correlated with the fall in gamma of UAL (deltagamma) (deltaRDI = 1.8 x deltagamma, r = 0.68, P = 0.04). Hypopneas decreased approximately 50% from 42 +/- 8 to 20 +/- 5 events/h (n = 9, P < 0.03, paired t-test). The gamma of UAL measured the next morning remained low at 49.5 +/- 2.7 mN/m (n = 9, P < 0.001, ANOVA, compared with control). In conclusion, instillation of surfactant reduced the gamma of UAL in OSAHS patients and decreased Pcrit and the occurrence of hypopneas. Therapeutic manipulation of gamma of UAL may be beneficial in reducing the severity of sleep-disordered breathing in OSAHS patients.

The tachykinin NK1 receptor is crucial for the development of non-atopic airway inflammation and hyperresponsiveness

Mast cell activation, bronchoconstriction, inflammation and airway hyperreactivity are prominent features of non-atopic hypersensitivity reactions in mouse airways. We studied the role of tachykinin receptors in mice that were skin-sensitized with dinitrofluorobenzene (or vehicle) and challenged intranasally with dinitrobenzene sulfonic acid. Tachykinin NK1 receptor blockade, by treatment with the antagonist RP67580, or absence of the tachykinin NK1 receptor resulted in a strong reduction in the accumulation of neutrophils in the bronchoalveolar lavage fluid, and in the development of tracheal hyperreactivity in mice 48 h after challenge. In contrast, treatment with the tachykinin NK2 receptor antagonist SR48968 did not affect the dinitrofluorobenzene-induced hypersensitivity reaction. We have previously shown that mast cells play a crucial role in the development of non-atopic asthma. However, we did not observe an inhibitory effect of the tachykinin receptor antagonists or the genetic absence of tachykinin NK1 receptors on mast cell protease release. In conclusion, distal from mast cell activation, the tachykinin NK1 receptor is crucial for the infiltration of pulmonary neutrophils and the development of tracheal hyperreactivity in non-atopic asthma.

Mucin genes in horse airways: MUC5AC, but not MUC2, may play a role in recurrent airway obstruction

REASONS FOR PERFORMING STUDY

Increased mucin gene expression may be an important cause of mucus accumulation observed in recurrent airway obstruction (RAO)-affected horses. To date, however, no mucin gene sequences are available for the horse.

OBJECTIVES

To identify equine homologues of gel-forming mucins and investigate their expression at different airway generations of healthy and RAO-affected horses.

METHODS

Two equine homologues were identified by cloning and sequencing fragments of equine (eq)MUC5AC and eqMUC2.

RESULTS

Semiquantitative RT-PCR on RNA from airways (generations 1, 5, 10, 15; small airways and parenchyma), stomach (glandular), and colon revealed that eqMUC5AC is expressed in equine stomach and in all of the airway samples. In contrast, eqMUC2 steady-state mRNA levels were detected in colon and very faintly in stomach, but not in airway tissue. EqMUC5AC expression was also compared to that of ZO-1, a tight junction protein, and eqMUC5AC/ZO-1 ratios were higher in RAO-affected compared to control horses at all airway generations.

CONCLUSIONS

That eqMUC5AC is expressed in horse airways, but any expression of MUC2 is undetectable and unlikely to be of physiological consequence.

POTENTIAL RELEVANCE

EqMUC5AC up-regulation may be a primary mechanism responsible for mucus hypersecretion and accumulation in RAO.

Neuronal nitric oxide synthase is associated with airway obstruction in BALB/c mice exposed to ozone

BACKGROUND

The functional role of nitric oxide (NO) and the various nitric oxide synthase (NOS) isoforms in asthma is controversial.

OBJECTIVE

To investigate the role of NO in mice exposed to ozone, three known isoforms of NOS [inducible NOS (iNOS), neuronal NOS (nNOS), and endothelial NOS (eNOS)] were studied.

METHODS

The expression of iNOS, nNOS, and eNOS was determined in lung by Western blot analysis after exposure to filtered air and ozone (0.12, 0.5, 1 or 2 ppm) for 3 h. Using barometric whole-body plethysmography and increase in enhanced pause (P(enh)) as an index of airway obstruction, we measured airway responses to ozone exposure. Bronchoalveolar lavage (BAL) was performed. Nitrate and nitrite were measured using a modified Griess reaction.

RESULTS

The nitrate concentration in BAL fluid, which indicates the in vivo generation of NO in airways, from the ozone-exposed group was significantly greater than that from the group exposed to filtered air (631.0 +/- 86.4 vs. 152.1 +/- 16.9 micromol/l, p < 0.05). The nitrate concentration in BAL fluid was increased more in mice exposed to 2-ppm ozone than that in mice exposed to filtered air or 0.12-, 0.5-, or 1-ppm ozone. Increases in P(enh) after exposure to ozone or filtered air were significantly higher in the ozone-exposed groups than in the group exposed to filtered air (p < 0.01). Increases in P(enh) were dependent on the ozone concentration. Although the protein levels of eNOS and iNOS determined were within normal levels, the amount of nNOS protein was markedly elevated in airway tissue homogenates of the group exposed to 2-ppm ozone.

CONCLUSION

These findings demonstrate that the nNOS isoform may be involved in airway obstruction in mice exposed to ozone.

[Role of fibroblasts in bronchial asthma]

The major role of fibroblasts is maintaining integrity, solidity and form of lung tissue. This is achieved by producing a vest variety of extracellular matrix (ECM) components such as collagen, laminin, fibronectin, hyaluronic acid and proteoglycans. Remodeling in the airways as seen in asthma is largely a result of altered fibroblast behavior. Fibroblasts produces a variety of inflammatory cytokines, chemokines and surface molecules which are able to activate and attract that stimulate inflammatory reactions. This paper presents a review of the fibroblast behavior and their interaction in the ongoing inflammatory and remodeling processes of the airway in asthma. Further we discuss the influence of glucocorticoids and long-acting beta 2-agonists on fibroblast in relation to their beneficial clinical effects in asthma therapy.

Evaluation of leukotriene biosynthetic capacity in lung tissues from horses with recurrent airway obstruction

OBJECTIVE

To evaluate leukotriene (LT) biosynthetic capacity in lung tissue from healthy horses and horses with recurrent airway obstruction (RAO).

SAMPLE POPULATION

Lung parenchyma and airway specimens from 8 RAO-affected and 5 healthy horses.

PROCEDURE

Horses were stabled for > or = 72 hours. Blood was drawn before euthanasia, after which lung specimens were collected. Tissue strips from small airways and parenchyma were incubated in organ baths with the precursor LTA4 or stimulated with calcium ionophore A23187 or the tripeptide N-formyl-Met-Leu-Phe (fMLP), with or without exogenous arachidonic acid, in the presence of isolated blood neutrophils.

RESULTS

Stabling induced typical clinical signs of airway obstruction in RAO-affected horses but not control horses. When lung parenchyma or airway specimens from both groups of horses were incubated with calcium ionophore, with or without arachidonic acid, they did not form LT. In contrast, addition of LTA4 to both tissues resulted in conversion to LTB4, although concentrations of LTC4 were negligible in airways and parenchymal strips from healthy and RAO-affected horses. Incubation of airway and parenchymal strips with suspensions of autologous neutrophils did not influence formation of LT stimulated by calcium ionophore or fMLP, with or without exogenous arachidonic acid.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that lung parenchyma and airway tissues themselves are not of substantial importance for LT formation in the lungs, although these tissues possessed some LTA4 hydrolase activity, enabling LTB4 formation. It may be speculated that LTB4 originates primarily from neutrophils and may play a role in the inflammatory events of RAO.

Piceatannol, a Syk-selective tyrosine kinase inhibitor, attenuated antigen challenge of guinea pig airways in vitro

Activation of nontransmembrane protein tyrosine kinases, such as Lyn and Syk, has been shown to be the earliest detectable signaling response to Fc receptor (Fc epsilon RI) cross-linking on mast cells leading to mast cell degranulation. The present study examined the effects of piceatannol (3,4,3',5'-tetrahydroxy-trans-stilbene, 10-100 microM), a Syk-selective tyrosine kinase inhibitor, on ovalbumin-induced anaphylactic contraction of isolated guinea pig bronchi and release of histamine and peptidoleukotrienes from chopped lung preparations. Pretreatment with piceatannol slightly suppressed ovalbumin-induced peak anaphylactic bronchial contraction but markedly (P<0.05) facilitated relaxation of the anaphylactically contracted bronchi. Piceatannol did not inhibit direct histamine-, leukotriene D(4)- or KCl-induced bronchial contraction, nor revert an existing anaphylactic bronchial contraction. Piceatannol, at 30 microM and above, significantly (P<0.05) prevented ovalbumin-induced release of both histamine and peptidoleukotrienes from lung fragments. Piceatannol did not inhibit exogenous arachidonic acid-induced release of peptidoleukotrienes from lung fragments. Our data show for the first time that inhibition of Syk tyrosine kinase can attenuate anaphylactic bronchial contraction in vitro, probably via inhibition of mast cell degranulation.