New insights into the pathophysiology of the small airways in asthma

Correlation between impulse oscillometry parameters and test for respiratory and asthma control in kids (TRACK) in asthma control of preschoolers with asthma

BACKGROUND

Little research has been conducted to evaluate the correlation between impulse oscillometry (IOS), Childhood Asthma Control Test (C-ACT), and Test for Respiratory and Asthma Control in Kids (TRACK).

METHODS

This study was conducted at China Medical University Hospital between September 1, 2019, and March 31, 2021. Children aged 2-6 years who had been diagnosed with asthma with acute exacerbation were enrolled and followed-up until the end of the study. Correlations between the parameters of IOS, C-ACT and TRACK were assessed. The validity and reliability of TRACK were verified.

RESULTS

A total of 114 children with asthma and acute exacerbations were recruited. Their mean age was 4.1 ± 1.1 years, and 60.5% were males. After a year of treatment, the change of R5-R20 from baseline 0.64 ± 0.38 kPa/L/s to 12th month 0.48 ± 0.2 kPa/L/s (p = 0.022). TRACK and C-ACT scores were significantly correlated during the observation period. R5-R20 in IOS at baseline and at the 12th month of follow-up as well as the change in IOS parameters were significantly associated with C-ACT (p = 0.003, 0.015, and 0.001, respectively). R5% and R5-R20 changes in IOS were associated with TRACK (p = 0.04 and 0.025, respectively). Sensitivity and specificity of TRACK were 80.8% (67.5-90.4) and 100% (94.1-100), respectively, with cut-off points >95 and AUC 93.8%.

CONCLUSION

TRACK score appears to have a stronger association with the IOS parameter than C-ACT score. Our findings indicate that TRACK is a valid tool for assessing asthma control in preschool children.

Effects of Medication Use on Small Airway Function and Airway Inflammation in Patients with Clinically Controlled Asthma

OBJECTIVE

To observe effects of medication use on small airway function, airway inflammation and acute exacerbations in patients with clinically controlled asthma.

METHODS

Forced expiratory flow over the middle half of the forced expiratory curve (FEF_25%-75%), percentage of eosinophil, concentrations of eosinophil cationic protein (ECP) and interleukin (IL)-5 in induced sputum were assessed in patients with clinically controlled asthma who were given oral anti-inflammatory agents alone or in combination with inhaled therapy and inhaled therapy alone. Subsequently, acute exacerbations were compared between two groups during the 24-week follow-up period.

RESULTS

FEF_25%-75% in 43 patients with clinically controlled asthma given oral anti-inflammatory agents alone or in combination with inhaled therapy was significantly higher than that in 49 patients given inhaled therapy alone. Meanwhile, the percentage of eosinophils and levels of IL-5 and ECP in patients with clinically controlled asthma given oral anti-inflammatory agents alone or in combination with inhaled therapy were significantly lower than those in patients given inhaled therapy alone. Additionally, the patients with clinically controlled asthma given inhaled therapy were likely to have more acute exacerbation than the patients given oral anti-inflammatory agents alone or in combination with inhaled therapy during the 24-week follow-up period.

CONCLUSION

Systemic anti-inflammatory agents may have a greater effect on parameters reflecting small airway patency and reducing acute exacerbations, presumably secondary to reduction in airway inflammation.

Turkish Thoracic Society Consensus Report: Interpretation of Spirometry

ÖZET: Günümüzde spirometre ölçümlerinin uygulama ve yorumlama nitelik güvencesi "American Thoracic Society / European Respiratory Society" standartları ile belirlenmiştir. Dünyada olduğu gibi ülkemizde de birçok laboratuvar bu standartları kullanmaktadır. Buna karşın, farklı laboratuvarlardan farklı değerlendirme sonuçları görebilmek mümkündür. Bu rapor, ülkemizdeki solunum fonksiyon testi laboratuvarlarında yapılan değerlendirmelerin standardizasyonunu sağlamak amacı ile hazırlanmıştır.

An Official American Thoracic Society Research Statement: Current Challenges Facing Research and Therapeutic Advances in Airway Remodeling

BACKGROUND

Airway remodeling (AR) is a prominent feature of asthma and other obstructive lung diseases that is minimally affected by current treatments. The goals of this Official American Thoracic Society (ATS) Research Statement are to discuss the scientific, technological, economic, and regulatory issues that deter progress of AR research and development of therapeutics targeting AR and to propose approaches and solutions to these specific problems. This Statement is not intended to provide clinical practice recommendations on any disease in which AR is observed and/or plays a role.

METHODS

An international multidisciplinary group from within academia, industry, and the National Institutes of Health, with expertise in multimodal approaches to the study of airway structure and function, pulmonary research and clinical practice in obstructive lung disease, and drug discovery platforms was invited to participate in one internet-based and one face-to-face meeting to address the above-stated goals. Although the majority of the analysis related to AR was in asthma, AR in other diseases was also discussed and considered in the recommendations. A literature search of PubMed was performed to support conclusions. The search was not a systematic review of the evidence.

RESULTS

Multiple conceptual, logistical, economic, and regulatory deterrents were identified that limit the performance of AR research and impede accelerated, intensive development of AR-focused therapeutics. Complementary solutions that leverage expertise of academia and industry were proposed to address them.

CONCLUSIONS

To date, numerous factors related to the intrinsic difficulty in performing AR research, and economic forces that are disincentives for the pursuit of AR treatments, have thwarted the ability to understand AR pathology and mechanisms and to address it clinically. This ATS Research Statement identifies potential solutions for each of these factors and emphasizes the importance of educating the global research community as to the extent of the problem as a critical first step in developing effective strategies for: (1) increasing the extent and impact of AR research and (2) developing, testing, and ultimately improving drugs targeting AR.

Airway eosinophil migration into lymph nodes in mice depends on leukotriene C4

BACKGROUND

We previously demonstrated in mice that airway eosinophils traffic from the airway lumen into lung-draining paratracheal lymph nodes. However, mechanisms whereby eosinophils traverse from the lungs and home to paratracheal lymph nodes remain unclear. We investigated roles of cysteinyl leukotrienes in mediating eosinophil trafficking from lungs to paratracheal lymph nodes.

METHODS

The expression of CCR7 was determined by flow cytometry. Transwell assays were used to test chemotactic responses of leukotriene C₄ synthase-deficient and control airway eosinophils to the chemokine CCL19 ex vivo. Eosinophils from the spleens of IL-5 transgenic mice, fluorescently labeled ex vivo, were intratracheally injected into ovalbumin-sensitized and ovalbumin aerosol-challenged leukotriene C₄ synthase-deficient and control mice. Eosinophils were identified by microscopy and flow cytometry in the lungs and paratracheal lymph nodes.

RESULTS

Mouse eosinophils expressed CCR7, the receptor for CCL19, and responded chemotactically to CCL19. Leukotriene C₄ synthase-deficient eosinophils exhibited impaired chemotaxis to CCL19 that was restored by exogenous leukotriene C₄ . The migration of intratracheally injected eosinophils into paratracheal lymph nodes from distal alveolar lung was diminished in leukotriene C₄ synthase-deficient mice compared with wild-type mice, with increased retention of eosinophils in the lungs of leukotriene C₄ synthase-deficient mice. Exogenous administration of leukotriene C₄ restored trafficking of eosinophils to paratracheal lymph nodes in leukotriene C₄ synthase-deficient mice.

CONCLUSIONS

Our findings that cysteinyl leukotrienes are involved in regulating airway and lung eosinophil migration into paratracheal lymph nodes identify previously unrecognized roles for the cysteinyl leukotrienes in regulating the pulmonary trafficking of eosinophils in experimental allergic asthma.

Computer modeling of airway deposition distribution of Foster(®) NEXThaler(®) and Seretide(®) Diskus(®) dry powder combination drugs

Asthma is a serious global health problem with rising prevalence and treatment costs. Due to the growing number of different types of inhalation devices and aerosol drugs, physicians often face difficulties in choosing the right medication for their patients. The main objectives of this study are (i) to elucidate the possibility and the advantages of the application of numerical modeling techniques in aerosol drug and device selection, and (ii) to demonstrate the possibility of the optimization of inhalation modes in asthma therapy with a numerical lung model by simulating patient-specific drug deposition distributions. In this study we measured inhalation parameter values of 25 healthy adult volunteers when using Foster(®) NEXThaler(®) and Seretide(®) Diskus(®). Relationships between emitted doses and patient-specific inhalation flow rates were established. Furthermore, individualized emitted particle size distributions were determined applying size distributions at measured flow rates. Based on the measured breathing parameter values, we calculated patient-specific drug deposition distributions for the active components (steroid and bronchodilator) of both drugs by the help of a validated aerosol lung deposition model adapted to therapeutic aerosols. Deposited dose fractions and deposition densities have been computed in the entire respiratory tract, in distinct anatomical regions of the airways and at the level of airway generations. We found that Foster(®) NEXThaler(®) deposits more efficiently in the lungs (average deposited steroid dose: 42.32±5.76% of the nominal emitted dose) than Seretide(®) Diskus(®) (average deposited steroid dose: 24.33±2.83% of the nominal emitted dose), but the variance of the deposition values of different individuals in the lung is significant. In addition, there are differences in the required minimal flow rates, therefore at certain patients Seretide(®) Diskus(®) or pMDIs could be a better choice. Our results show that validated computer deposition models could be useful tools in providing valuable deposition data and assisting health professionals in the personalized drug selection and delivery optimization. Patient-specific modeling could open a new horizon in the treatment of asthma towards a more effective personalized medicine in the future.

Improved metered dose inhaler technique when a coordination cap is used

BACKGROUND

Patients often experience problems using metered dose inhalers (MDIs), particularly poor coordination between inhalation start and dose actuation (TsIn: time difference between the start of an inhalation and the actuation of a dose), and fast peak inspiratory flow (PIF). We investigated if a coordination cap (CAP), with instruction to prolong inhalation, solved these problems.

METHODS

Inhalation profiles [PIF, TsIn, inhalation volume (Vi), inhalation time (Ti)] of patients with stable asthma prescribed an MDI were measured using their real-life technique (MDI). Inhalation profiles were then measured with the cap fitted (MDI+CAP). These patients were then instructed to inhale through the MDI+CAP for 5 sec, and inhalation profiles measured (MDI+CAP+TRAIN). TsIn was only measured for the MDI.

RESULTS

Resistances of MDI and MDI+CAP were 0.0135 and 0.0243 (cm H2O)(½)/(L/min), respectively. Seventy-one patients were evaluated, with mean [standard deviation (SD)] forced expiratory volume over 1 sec % predicted normal of 78.3% (21.0). Following MDI, MDI+CAP, and MDI+CAP+TRAIN: mean (SD) PIF was 155.6 (61.5), 112.3 (48.4), and 73.8 (34.9) L/min, respectively (p<0.001); mean (SD) Ti was 1.60 (0.60), 1.92 (0.80), and 2.99 (1.03) sec, respectively (p<0.001); and Vi was similar between stages. Twelve patients used a slow flow with the MDI alone, but only two of these patients demonstrated good coordination. With the cap in place (which ensures good coordination), the number of patients using a slow flow increased to 25 for MDI+CAP and to 50 following MDI+CAP+TRAIN.

CONCLUSIONS

The cap with its effect of increasing resistance to airflow combined with the instruction to prolong inhalation time significantly decreased the inhalation flow.

Efficacy of theophylline plus salmeterol/fluticasone propionate combination therapy in patients with asthma

OBJECTIVE

To compare the efficacy of theophylline plus salmeterol/fluticasone propionate combination product (SFC) with SFC plus placebo in asthmatic patients.

METHODS

In this randomized, stratified, parallel-group study, 325 patients were randomized to receive either 200 mg theophylline plus 50/250 μg SFC or placebo tablet plus 50/250 μg SFC twice daily for 24 weeks. Outcome variables included the level of asthma control (assessed by the Asthma Control Test) and the number of patients experiencing ≥1 exacerbations during the 24-week treatment period. Testing of lung function as well as measurement of the levels of inflammatory markers in induced sputum was performed.

RESULTS

There were significantly fewer patients with ≥1 asthma exacerbation in the theophylline plus SFC group (29.6%) when compared with the SFC plus placebo group (46.9%) (p = 0.004). Theophylline plus SFC improved the FEF(25-75%) value, which indicates enhanced small airway function, to a greater extent than SFC plus placebo (66.9 ± 18.8% and 57.4 ± 17.6%, respectively; p < 0.001). A significant decrease in eosinophil count and concentration of eosinophil cationic protein in induced sputum was also seen in the theophylline plus SFC group when compared with the SFC plus placebo group (4.1 ± 2.2% and 6.3 ± 2.7%, 63.6 ± 39.5 μg/L and 89.4 ± 45.6 μg/L, respectively; all p < 0.01).

CONCLUSION

The combination of theophylline plus SFC may provide greater protection against asthma exacerbations, and its administration is accompanied by significant improvements in small airway function and airway inflammation.

Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo

We evaluated the airway distention during lung inflation of varying size in healthy and allergic-sensitised mice in vivo. Computed tomography (CT) images of healthy and ovalbumin-treated mice were acquired using a synchrotron in vivo CT system when lung pressures was 0 and 20 cmH(2)O, and the morphometric distension (diameter, length, and volume) and the compliance of airway segments (to as small as ~150 μm internal diameter) were calculated. With respect to airway size, in healthy mice, the changes in airway diameter and compliance were larger in the small-airway group. In contrast, in allergic-sensitised mice, there were no significant differences in the changes in airway distension or compliance. Airway wall thickness in allergic-sensitised mice increased significantly in all airway groups, but the change was much larger in the small than in the large-airway group. Compared with healthy airways, the changes in diameter and airway compliance of the allergic-sensitised mice were significantly smaller in the small-airway group.

Untangling asthma phenotypes and endotypes

Asthma phenotypes have been developed to address the complexities of the disease. However, owing to a lack of longitudinal studies, little is known about the onset as well as the stability of phenotypes. Distinguishing phenotypes with regard to the severity or duration of the disease is essential. A phenotype covers the clinically relevant properties of the disease, but does not show the direct relationship to disease etiology and pathophysiology. Different pathogenetic mechanisms might cause similar asthma symptoms and might be operant in a certain phenotype. These putative mechanisms are addressed by the term 'endotype'. Classification of asthma based on endotypes provides advantages for epidemiological, genetic, and drug-related studies. A successful definition of endotypes should link key pathogenic mechanisms with the asthma phenotype. Thus, the identification of corresponding molecular biomarkers for individual pathogenic mechanism underlying phenotypes or subgroups within a phenotype is important. Whether newly defined asthma endotypes predict the individual course of asthma has to be validated in longitudinal studies. The accurate endotyping reflects natural history of asthma and should help to predict treatment response. Thus, understanding asthma endotypes might be useful in clinical practice.

CCAAT/enhancer binding protein-α regulates the protease/antiprotease balance required for bronchiolar epithelium regeneration

Many transcription factors that regulate lung morphogenesis during development are reactivated to mediate repairs of the injured adult lung. We hypothesized that CCAAT/enhancer binding protein-α (C/EBPα), a transcription factor critical for perinatal lung maturation, regulates genes required for the normal repair of the bronchiolar epithelium after injury. Transgenic Cebpα(Δ/Δ) mice, in which Cebpa was conditionally deleted from Clara cells and Type II cells after birth, were used in this study. Airway injury was induced in mice by the intraperitoneal administration of naphthalene to ablate bronchiolar epithelial cells. Although the deletion of C/EBPα did not influence lung structure and function under unstressed conditions, C/EBPα was required for the normal repair of terminal bronchiolar epithelium after naphthalene injury. To identify cellular processes that are influenced by C/EBPα during repair, mRNA microarray was performed on terminal bronchiolar epithelial cells isolated by laser-capture microdissection. Normal repair of the terminal bronchiolar epithelium was highly associated with the mRNAs regulating antiprotease activities, and their induction required C/EBPα. The defective deposition of fibronectin in Cebpα(Δ/Δ) mice was associated with increased protease activity and delayed differentiation of FoxJ1-expressing ciliated cells. The fibronectin and ciliated cells were restored by the intratracheal treatment of Cebpα(Δ/Δ) mice with the serine protease inhibitor. In conclusion, C/EBPα regulates the expression of serine protease inhibitors that are required for the normal increase of fibronectin and the restoration of ciliated cells after injury. Treatment with serine protease inhibitor may aid in the recovery of injured bronchiolar epithelial cells, and prevent common chronic lung diseases.

Environment and T regulatory cells in allergy

The central role of T regulatory cells in the responses against harmless environmental antigens has been confirmed by many studies. Impaired T regulatory cell function is implicated in many pathological conditions, particularly allergic diseases. The "hygiene hypothesis" suggests that infections and infestations may play a protective role for allergy, whereas environmental pollutants favor the development of allergic diseases. Developing countries suffer from a variety of infections and are also facing an increasing diffusion of environmental pollutants. In these countries allergies increase in relation to the spreading use of xenobiotics (pesticides, herbicides, pollution, etc.) with a rate similar to those of developed countries, overcoming the protective effects of infections. We review here the main mechanisms of non-self tolerance, with particular regard to relations between T regulatory cell activity, infections and infestations such as helminthiasis, and exposure to environmental xenobiotics with relevant diffusion in developing countries.

Airway dimensions and pulmonary function in chronic obstructive pulmonary disease and bronchial asthma

BACKGROUND AND OBJECTIVE

COPD and bronchial asthma are chronic airway diseases with a different pathogenesis. Comparisons of differences in airway calibre by bronchial generation between these diseases and their importance to pulmonary function have not been fully studied. We investigated airway calibre and wall thickness in relation to pulmonary function in patients with asthma, COPD, asthma plus emphysema and normal subjects using CT.

METHODS

Sixty-three asthmatic patients, 46 COPD, 23 patients with asthma plus emphysema and 61 control subjects were studied cross-sectionally. We used a software with curved multiplanar reconstruction to measure airway dimensions from 3rd- to 6th-generation bronchi of the right lower posterior bronchus.

RESULTS

Patients with COPD had increased wall thickness, but the airway was not narrow from the 3rd-(subsegmental) to 6th-generation bronchi. Mean bronchial inner diameter (Di) of 3rd- to 6th-generation bronchi in patients with asthma or asthma plus emphysema was smaller than that of COPD patients and normal subjects. Airway luminal area (Ai) of 5th-generation bronchi most closely correlated with pulmonary function in patients with stable asthma. Although Di was similar in patients with asthma and asthma plus emphysema, the Ai of 6th-generation bronchi correlated significantly with pulmonary function in patients with asthma plus emphysema.

CONCLUSIONS

Airway calibre in asthma may be smaller than in COPD. Airflow limitations correlated more closely with peripheral Ai in patients with asthma plus emphysema than in patients with asthma alone.

Comparison of high-dose salmeterol/fluticasone and moderate-dose salmeterol/fluticasone plus low-dose mometasone in patients with severe persistent asthma

BACKGROUND AND OBJECTIVE

The effects of adding a second inhaled corticosteroid with a different particle size, compared with using an increased dose of a single inhaled corticosteroid, were assessed in patients with persistent asthma.

METHODS

This was an open-label study of Japanese asthma patients over 20 years of age. After a 1-month run-in period, 36 patients with inadequate control while using salmeterol/fluticasone propionate 50/250 µg (SFC50/250) bd, were randomized to receive SFC50/500 bd or SFC50/250 plus mometasone 100 µg bd (SFC50/250/MF100) for 2 months.

RESULTS

Both treatments resulted in improvements in morning and evening PEF. There were no significant changes in FEV(1) , maximum mid-expiratory flow, maximum expiratory flow rate at 50%, maximum expiratory flow rate at 25% or exhaled NO (FENO) in the SFC50/500 group. On the other hand, there were significant improvements in FEV(1) % (+12.2%, P = 0.0142), %maximum mid-expiratory flow (+28.9%, P = 0.0181), %MEF50 (+32.4%, P = 0.0206) and %MEF25 (+30.3%, P = 0.0113) in the SFC50/250/MF100 group. The changes in FENO (-23.2% (P = 0.0157) in the SFC50/250/MF100 group and -14.5% (not significant) in the SFC50/500 group) did not differ significantly between the groups.

CONCLUSIONS

In patients with severe persistent asthma, addition of low-dose mometasone to SFC50/250 improved spirometric parameters, FENO and PEF, while an increase in dose from SFC50/250 to SFC50/ 500 only improved PEF.

[Inflammation and remodeling of the distal airways: studies in humans and experimental models]

Asthma is characterized by inflammation and remodeling of the airways, giving rise to airway obstruction and symptoms of wheezing, chest tightness, cough and dyspnea. Most of these observations arise from the study of samples obtained from the central airways by distinct methods. However, it is currently accepted that this inflammatory process occurs not only in the central airway but also in the small airway and even in the pulmonary parenchyma of all asthmatic patients, even those with mild asthma. CD4+ lymphocytes, activated eosinophils and IL-5 mRNA expression are present in a greater quantity in the small airways. Also present is remodeling, with an increase in submucosal thickness, the muscular layer and adventitia. This inflammatory process causes a disconnection between the pulmonary parenchyma and the airway, giving rise to obstruction of the small airway, which is currently considered to be predominant in asthmatic patients. Likewise, studies of experimental asthma in animals support the substantial role of the distal airway. Recognition that asthma affects the entire airway could be clinically important and lead to the distal lung being considered as a target in any effective therapeutic strategy. However, longitudinal studies are required to evaluate the impact of distal airway inflammation and its treatment in asthma.

[Clinical relevance of distal airway involvement in asthma]

Asthma continues to be a global health problem, despite advances in diagnostic techniques and treatment. The inflammatory nature of asthma is currently indisputable, as is the involvement of the entire respiratory tree, both the proximal and most distal airways, which has been demonstrated in multiple studies. The development of the therapeutic arsenal, with more potent drugs and improved inhalation devices, has allowed a certain control to be maintained over the inflammatory process, although the inability to reach the most distal points of the airways has posed a stumbling block that seems difficult to overcome. However, the available information on the real role of distal airway involvement in asthma remains very scarce. Physiopathological evidence shows that, in addition to the large airways, the small or distal airways (those with a diameter of less than 2 mm) substantially contribute to the severity of asthma. Several studies have shown that the inflammatory process seems to be more intense in this area. This finding has been related to nocturnal asthma and an increase in glucocorticoid receptor-beta-expressing cells, associated with corticosteroid-resistant asthma and fatal asthma. Equally, small airway involvement seems to be a highly important factor in asthma in the pediatric age group.

Improving asthma care for African American children by increasing national asthma guideline adherence

INTRODUCTION

Children, particularly African American children, bear a disproportionate burden of asthma and are at highest risk for associated morbidity and mortality. The under-utilization of the National Asthma Education and Prevention Program (NAEPP) guidelines across all demographics and the under use of inhaled corticosteroids (ICS) as controller therapy in these children are well-documented. The primary aim of this study was to increase health care provider (HCP) adherence to the NAEPP guidelines by means of a guideline reminder tool, the Multi-colored Simplified Asthma Guideline Reminder, consequently increasing the prescription of ICS in this population.

METHOD

This study had a pre-experimental design with descriptive analysis.

RESULTS

The Multi-colored Simplified Asthma Guideline Reminder was effective in increasing HCP adherence to the NAEPP guidelines as evidenced by increased use of ICS as controller therapy.

DISCUSSION

Despite the increasing prevalence and burden of asthma in African American children, the associated prescriptive use of ICS has not increased substantially in the past decade. The greatest obstacle in the scope of improving asthma outcomes is the underuse of ICS by HCPs.

Mega-dose vitamin C attenuated lung inflammation in mouse asthma model

Asthma is a Th2-dependent disease mediated by IgE and Th2 cytokines, and asthmatic patients suffer from oxidative stresses from abnormal airway inflammation. Vitamin C is a micro-nutrient functioning as an antioxidant. When administered at a mega-dose, vitamin C has been reported to shift immune responses toward Th1. Thus, we tried to determine whether vitamin C exerted beneficial effects in asthma animal model. Asthma was induced in mice by sensitizing and challenging with ovalbumin. At the time of challenge, 3~5 mg of vitamin C was administered and the effects were evaluated. Vitamin C did not modulate Th1/Th2 balance in asthma model. However, it decreased airway hyperreactivity to methacholine, decreased inflammatory cell numbers in brochoalveolar lavage fluid, and moderate reduction of perivascular and peribronchiolar inflammatory cell infiltration. These results suggest that vitamin C administered at the time of antigen challenge exerted anti-inflammatory effects. Further studies based on chronic asthma model are needed to evaluate a long-term effect of vitamin C in asthma. In conclusion, even though vitamin C did not show any Th1/Th2 shifting effects in this experiment, it still exerted moderate anti-inflammatory effects. Considering other beneficial effects and inexpensiveness of vitamin C, mega-dose usage of vitamin C could be a potential supplementary modality for the management of asthma.

Remodeling in asthma and COPD--differences and similarities

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are both inflammatory disorders. Diagnosis of these diseases is based upon limitation of expiratory airflow. The pathophysiological correlates to this impaired lung function are complex but they are associated with the development of structural changes in the airways and lung parenchyma. These remodeling processes differ between the two diseases. In asthma, airways obstruction is predominately located in the large airways, although recent studies indicate that inflammation and structural changes also is present in other compartments of the lungs. In COPD, remodeling of the small airways and lung parenchyma are the main correlates to the limitation of expiratory airflow. However, both asthma and COPD are heterogeneous disorders including various phenotypes and there is a considerable overlap between the two diseases.

METHODS AND RESULTS

In the present review, airway remodeling in asthma and COPD will be discussed in three different compartments of the airways: large airways, small airways and lung parenchyma. Different inflammatory cells will be mentioned, as well as markers of remodeling.

CONCLUSION

In COPD and severe asthma, current anti-inflammatory pharmacotherapy does not restore lung function impairment fully. It is therefore recognized that research aiming to explore mechanisms of airway remodeling should be encouraged.

New production of eosinophils and the corresponding TH1/TH2 balance in the lungs after allergen exposure in BALB/c and C57BL/6 mice

Allergic asthma is associated with eosinophilic inflammation in the airways. Animal models commonly used to elucidate allergic inflammation mechanisms include BALB/c and C57BL/6 mice. Our aim was to evaluate lung eosinophilia and the corresponding Th1/Th2 balance in the two strains after allergen exposure. BALB/c and C57BL/6 mice were subjected to ovalbumin-induced allergic airway inflammation using BrdU to label newly produced cells. The numbers of new eosinophils were evaluated by differential cell count and immunocytochemistry (MBP+BrdU+). Proliferation rate of lung eosinophils was measured by analysis of CD45+CCR3+BrdU+ cells by FACS. Distribution of newly produced eosinophils in the lung and the Th1/Th2 (CD4+T-bet+/CD4+GATA-3+) balance was evaluated by immunohistochemistry. Allergen challenge with ovalbumin induced comparable eosinophilia in bone marrow (BM), blood and lung tissue in both strains of mice compared to phosphate-buffered saline controls, which was confirmed by immunocytochemistry. There was a small increase in the number of lung MBP+BrdU(-) eosinophils in C57BL/6 mice compared to BALB/c mice, which suggests a basal increase in this strain following sensitization. While there was no difference in eosinophilic proliferation in the lung, the distribution of the newly produced eosinophils differs between the two strains. BALB/c mice showed staining primarily around vessels and airways, whereas C57BL/6 mice showed a more even distribution in the lung tissue. No difference in the Th1/Th2 balance was observed between two strains. This study shows that there is a difference in the distribution of eosinophils in the lung between the C57BL/6 and BALB/c mice, but no difference in eosinophil production or Th1/Th2 balance.

Choosing inhaler devices for people with asthma: current knowledge and outstanding research needs

Recommendations in asthma guidelines presuppose that practitioners have the evidence, information, knowledge, and tools to select inhaler devices appropriate for individual patients. Randomised controlled trials usually exclude patients with suboptimal inhaler technique. There is therefore little evidence on which to base inhaler selection in the real world, where patients often use their inhalers incorrectly. The lung deposition of inhaled drug varies according to inhaler device, drug particle size, inhalation technique, and pattern of inspiratory flow. Even with training, not all patients can use their inhalers correctly and maintain inhaler technique; patients may have inability to handle the inhaler, strong negative preferences, or natural breathing patterns that do not match their prescribed inhaler. Therefore, matching device to the patient may be a better course of action than increasing therapy or training and retraining a patient to use a specific inhaler device. Several research questions require answers to meet the goal of helping prescribers make a more informed choice of inhaler type. Is the level of drug deposition in the lungs a key determinant of clinical short- and long-term outcomes? What should be measured by a clinical tool designed to check inhaler technique and therefore help with device selection? If we have a tool to help in individualising inhaler choice, will we achieve better asthma outcomes? Do we have to refine inhaler device choice for each individual, or will we get better outcomes if we select our current best option in light of current knowledge and apply this on a population level?

Effect of inhaled corticosteroids on small airways in asthma: investigation using impulse oscillometry

BACKGROUND

Small airways appear to have an important role in asthma. Hydrofluoroalkane-134a beclomethasone dipropionate (HFA-BDP) has ultrafine particles and accordingly greater deposition in the small airways than chlorofluorocarbon (CFC)-BDP. Impulse oscillometry systems (IOS), a new and non-invasive measure of pulmonary function, can examine the resistance of total (R5), large (R20), and small airways (R5-R20) separately, and low-frequency reactance area (AX), also considered a measure of small airways dysfunction.

METHODS

Mild-to-moderate asthmatics who were inhaled corticosteroid naïve were randomized to receive 200 mcg HFA-BDP bid (n 1/4 26) or 400 mcg CFC-BDP bid (n 1/4 12) for 12 weeks in an open-label manner. Following baseline measurements, IOS and spirometry were repeated every 4 weeks, and methacholine challenge to separately assess airway sensitivity and airway reactivity and lung volumes at 12 weeks.

RESULTS

Moderate correlations were found between R5-R20 or AX and spirometry and lung volume indices of small airways, and between R20 and peak expiratory flow at baseline. The two groups did not significantly differ in baseline clinical or functional parameters. At 12 weeks, all IOS indices improved in the HFA-BDP group, whereas all but R5-R20 improved with CFC-BDP. R5-R20 and AX progressively improved with HFA-BDP; these changes achieved statistical significance at 12 weeks versus the CFC-BDP group. Other IOS and spirometry indices failed to show such trends. HFA-BDP significantly attenuated methacholine airway sensitivity; the degree of this attenuation strongly correlated with R5-R20 and AX baseline values, and with improvement of AX with treatment.

CONCLUSION

HFA-BDP is an effective treatment of small airways in asthma. Prolonged treatment provides a progressive effect over time, which is associated with an attenuation of airway responsiveness.

Irreversiblity of remodeled features on high-resolution computerized tomography scans of asthmatic patients on conventional therapy: a 6-year longitudinal study

Airway remodeling can be assessed using high-resolution computerized tomography (HRCT) scanning of both parenchymal-and airway abnormalities in patients with asthma. The aim of this study was to examine structural changes in large and small airways of asthmatic patients using HRCT to determine if remodeling changes had occurred after prolonged use of conventional anti-asthma therapy. HRCT scans were evaluated prospectively for evidence of the following abnormalities: bronchial wall thickening (BWT), bronchiectasis, mucoid impactions, small centrilobular opacities, thick linear opacities, focal hyperlucency, and emphysema. Fifty mild and moderate asthmatics were enrolled in the study group. These abnormalities were re-evaluated in the patients after the passage of 6 years of regular anti-asthma medication. Forty-six of the patients completed the study. The probability of finding at least one abnormality by HRCT investigation was statistically higher in the second scan than in the first (26 patients [56.5%] versus 18 patients [39.1%], p = 0.02]. Irreversibility ratios of abnormalities were 80%, 100%, 75%, 87.7%, 77.8%, and 100% for BWT, bronchiectasis, small centrilobular opacities, focal hyperlucency, thick linear opacity, and emphysema, respectively. The ratios for newly detected structural abnormalities were 25%, 2.5%, 0%, 7.9%, 8.1%, and 0% for BWT, bronchiectasis, small centrilobular opacities, focal hyperlucency, thick linear opacity, and emphysema, respectively. New occurrences and progression in BWT are associated with the duration of asthma affliction (p = 0.03). The results of our study indicate that HRCT remodeling features, once occurring, are irreversible in most of the patients, and new remodeling features also occur despite administering the standard asthma treatment.

The contribution of Ca2+ signaling and Ca2+ sensitivity to the regulation of airway smooth muscle contraction is different in rats and mice

To determine the relative contributions of Ca(2+) signaling and Ca(2+) sensitivity to the contractility of airway smooth muscle cells (SMCs), we compared the contractile responses of mouse and rat airways with the lung slice technique. Airway contraction was measured by monitoring changes in airway lumen area with phase-contrast microscopy, whereas changes in intracellular calcium concentration ([Ca(2+)](i)) of the SMCs were recorded with laser scanning microscopy. In mice and rats, methacholine (MCh) or serotonin induced concentration-dependent airway contraction and Ca(2+) oscillations in the SMCs. However, rat airways demonstrated greater contraction compared with mice, in response to agonist-induced Ca(2+) oscillations of a similar frequency. Because this indicates that rat airway SMCs have a higher Ca(2+) sensitivity compared with mice, we examined Ca(2+) sensitivity with Ca(2+)-permeabilized airway SMCs in which the [Ca(2+)](i) was experimentally controlled. In the absence of agonists, high [Ca(2+)](i) induced a sustained contraction in rat airways but only a transient contraction in mouse airways. This sustained contraction of rat airways was relaxed by Y-23672, a Rho kinase inhibitor, but not affected by GF-109203X, a PKC inhibitor. The subsequent exposure of Ca(2+)-permeabilized airway SMCs, with high [Ca(2+)](i), to MCh elicited a further contraction of rat airways and initiated a sustained contraction of mouse airways, without changing the [Ca(2+)](i) of the SMCs. Collectively, these results indicate that airway SMCs of rats have a substantially higher innate Ca(2+) sensitivity than mice and that this strongly influences the transduction of the frequency of Ca(2+) oscillations into the contractility of airway SMCs.

Inhaled beclometasone dipropionate/formoterol extra-fine fixed combination in the treatment of asthma: evidence and future perspectives

BACKGROUND

Combinations of a long-acting beta(2)-agonist (LABA) and an inhaled corticosteroid (ICS) are effective and safe options in asthma management.

OBJECTIVE

To review available data on a recently developed combination of beclometasone dipropionate (BDP) and formoterol (F) given via a pressurized metered-dose inhaler.

METHODS

Published data on preclinical and clinical studies were reviewed.

RESULTS/CONCLUSION

In the treatment of asthma, BDP/F was shown to be at least as effective and well-tolerated as other available combinations of ICS and LABA with the advantage of a better cost effectiveness, and more effective in improving asthma control than BDP and formoterol given via separate inhalers. The extra-fine BDP/F combination appears to be a valuable therapeutic option in the management of asthma.

Tissue Doppler echocardiographic assessment of cardiac function in children with bronchial asthma

BACKGROUND

The aim of the present study was to evaluate the role of tissue Doppler echocardiography in assessment of ventricular function in pediatric patients with bronchial asthma (BA).

PATIENTS AND METHODS

Fifty-one pediatric patients with BA and 30 age- and sex-matched healthy subjects were studied. BA patients were divided into two groups: mild BA (n = 33) and moderate to severe BA (n = 18). All subjects were examined on conventional and tissue Doppler echocardiography, and 44 patients had pulmonary function tests on spirometry within 1 week of echocardiographic examination.

RESULTS

Conventional echocardiographic parameters were all similar in mild asthmatic patients and control subjects. Tricuspid E velocity, E/A ratio and isovolumetric relaxation time (IVRT) in moderate and severe cases differed significantly from mild cases and control subjects. E', A', E'/A' ratio and IVRT of the lateral tricuspid annulus, and IVRT of the medial and lateral mitral annuli were different between mild cases and control subjects. E' velocity and IVRT of the lateral tricuspid annulus and IVRT of the medial and lateral mitral annuli were also different between mild cases and moderate to severe cases. Pulmonary function tests correlated well with E', E'/A' and IVRT of lateral tricuspid annulus.

CONCLUSION

Patients with BA have subclinical right ventricular diastolic dysfunction even in the early stages. The severity of the functional impairment is parallel with the severity of the disease. Tissue Doppler echocardiography has a greater predictive value than conventional imaging, and is useful for evaluating ventricular function in patients with BA.

Part III: Location of asthma inflammation and the distal airways: clinical implications

Accumulating evidence suggests that the airway inflammation and remodeling characteristic of asthma occur not only in the central airways, but also in the distal lung and the lung parenchyma. The distal airways are increasingly being recognized as important sites of airflow obstruction. Research indicates that distal inflammation may play a crucial role in airway hyperresponsiveness, nocturnal asthma, and spontaneous exacerbations of asthma symptoms. Although the effectiveness of inhaled corticosteroids in improving asthmatic symptoms and preventing exacerbations is well established, the ability of conventional formulations to reach the distal airways is limited. The impaired ability of these formulations to reach the distal airways may contribute to the observation that inhaled corticosteroids do not always provide adequate control of asthma symptoms. Newer formulations of inhaled corticosteroids that use hydrofluoroalkane (HFA) propellants in solution have greater access to the distal airways and produce beneficial changes in lung function. Due to their highly targeted delivery systems, newer HFA-based formulations have the potential to effectively treat asthma at reduced doses.

Differential flow analysis of exhaled nitric oxide in patients with asthma of differing severity

BACKGROUND

The majority of asthmatic patients achieve control of their illness; others do not. It is therefore crucial to validate/develop strategies that help the clinician monitor the disease, improving the response to treatment.

METHODS

We have quantified the inflammation in central and peripheral airways by measuring exhaled nitric oxide (NO) at multiple exhalation flows in 56 asthmatics at different levels of severity (mild, n = 10; moderate stable, n = 17; moderate during exacerbation, n = 11; severe, n = 18, 7 of whom were receiving oral corticosteroids) and 18 healthy control subjects. The reproducibility of the measurement was also assessed.

RESULTS

Bronchial NO (Jno) in patients with mild asthma (2,363 +/- 330 pL/s) [mean +/- SD] was higher than in patients with moderate stable asthma (1,300 +/- 59 pL/s, p < 0.0005), in patients with severe asthma receiving inhaled corticosteroids (ICS) [1,015 +/- 67 pL/s, p < 0.0005], and healthy control subjects (721 +/- 22 pL/s, p < 0.0001). There were no differences between Jno in patients with mild asthma compared to patients with severe asthma receiving ICS and oral corticosteroids (2,225 +/- 246 pL/s). Patients with exacerbations showed a higher Jno (3,475 +/- 368.9 pL/s, p < 0.05) compared to the other groups. Alveolar NO was higher in patients with severe asthma receiving oral corticosteroids (3.0 +/- 0.1 parts per billion [ppb], p < 0.0001) than in the other groups but was not significantly higher than in patients with moderate asthma during exacerbation (2.8 +/- 0.3 ppb). No differences were seen in NO diffusion levels between the different asthma groups. All the measurements were highly reproducible and free of day-to-day and diurnal variations.

CONCLUSIONS

Differential flow analysis of exhaled NO provides additional information about the site of inflammation in asthma and may be useful in assessing the response of peripheral inflammation to therapy.

Asthma: new developments concerning immune mechanisms, diagnosis and treatment

PURPOSE OF REVIEW

This brief review discusses how recent research may modify our understanding of the immunology of asthma. Consideration is given to the possible impact that these observations may have upon diagnostic and therapeutic strategies.

RECENT FINDINGS

New studies indicate that current conceptions regarding the balance between Th1 and Th2 systems may need modification. The relationship between infection and the development of asthma in children has proven to be much more complex than originally suggested by the 'hygiene hypothesis'. In addition, important genetic differences have been found in the response of asthmatic patients to therapeutic agents.

SUMMARY

Greater insight into the mechanisms responsible for asthma and the introduction of new drugs will depend in part upon the development of reliable and simple methods for detecting airway inflammation. As the immunologic aspects of asthma are dissected, we can expect that many more potential targets for treatment will be discovered, but treatment may have to be individualized for genetic differences between different individuals.

Discovery of a potent and long-acting bronchorelaxing capsazepinoid, RESPIR 4-95

BACKGROUND

Current drugs including beta-agonists have limited smooth muscle relaxant effects on human small airways. Yet this is a major site of obstruction in asthma and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

This study explores human small airway relaxant effects of RESPIR 4-95, a novel chemical analogue (capsazepinoid) to capsazepine. Capsazepine was recently shown to relax small airways in a way which was independent of its TRPV1 antagonism and independent of current bronchodilator drug mechanisms.

METHOD

In vitro preparations of human small airways, 0.5-1.5mm in diameter and responding with reproducible contractions to leukotriene D4 (LTD4) for 12h, were used.

RESULTS

RESPIR 4-95 reversibly prevented LTD4-induced contractions as well as relaxed the established tonic contraction by LTD4. RESPIR 4-95 exhibited marked improvements over the reference capsazepinoid, capsazepine, by being 10 times more potent, exhibiting twice as long duration of action after wash-out (9h), and inhibiting equally well LTD4-, histamine-, prostaglandin D2 (PGD2)-, and acetylcholine (ACh)-induced contractions. RESPIR 4-95 was distinguished from l-type calcium channel antagonist nifedipine by its greater efficacy and potency and by exhibiting increased relaxant effect by repeated exposures. Furthermore, RESPIR 4-95 was more efficacious and longer acting than the long-acting beta-agonist formoterol.

CONCLUSION

Efficacy, potency, duration of action, and inexhaustibility of its relaxation of human small airways make RESPIR 4-95 an interesting lead compound for further developments aiming at drug treatment of small airway obstruction in asthma and COPD. Further work is warranted to unveil the molecular biology behind its relaxant actions.

Small airway relaxation--a forgotten medical need

The current exclusive focus on airway inflammation and remodelling in asthma and chronic obstructive pulmonary disease has dwarfed the interest in simple relaxation of the bronchi. This commentary highlights the particular importance of reducing smooth muscle constriction of human small airways in these obstructive diseases. Furthermore, the need of novel drugs in this area is underscored by in vitro and in vivo data demonstrating limited small airway relaxant efficacy of currently available bronchodilators.