Association of epithelial damage and signs of neutrophil mobilization in the airways during acute exacerbations of paediatric asthma

Microcystin-LR aerosol induces inflammatory responses in healthy human primary airway epithelium

Harmful algal blooms plague bodies of freshwater globally. These blooms are often composed of outgrowths of cyanobacteria capable of producing the heptapeptide Microcystin-LR (MC-LR) which is a well-known hepatotoxin. Recently, MC-LR has been detected in aerosols generated from lake water. However, the risk for human health effects due to MC-LR inhalation exposure have not been extensively investigated. In this study, we exposed a fully differentiated 3D human airway epithelium derived from 14 healthy donors to MC-LR-containing aerosol once a day for 3 days. Concentrations of MC-LR ranged from 100 pM to 1 µM. Although there were little to no detrimental alterations in measures of the airway epithelial function (i.e. cell survival, tissue integrity, mucociliary clearance, or cilia beating frequency), a distinct shift in the transcriptional activity was found. Genes related to inflammation were found to be upregulated such as C-C motif chemokine 5 (CCL5; log2FC = 0.57, p = 0.03) and C-C chemokine receptor type 7 (CCR7; log2FC = 0.84, p = 0.03). Functionally, conditioned media from MC-LR exposed airway epithelium was also found to have significant chemo-attractive properties for primary human neutrophils. Additionally, increases were found in the concentration of secreted chemokine proteins in the conditioned media such as CCL1 (log2FC = 5.07, p = 0.0001) and CCL5 (log2FC = 1.02, p = 0.046). These results suggest that MC-LR exposure to the human airway epithelium is capable of inducing an inflammatory response that may potentiate acute or chronic disease.

Pulmonary Eosinophils at the Center of the Allergic Space-Time Continuum

Eosinophils are typically a minority population of circulating granulocytes being released from the bone-marrow as terminally differentiated cells. Besides their function in the defense against parasites and in promoting allergic airway inflammation, regulatory functions have now been attributed to eosinophils in various organs. Although eosinophils are involved in the inflammatory response to allergens, it remains unclear whether they are drivers of the asthma pathology or merely recruited effector cells. Recent findings highlight the homeostatic and pro-resolving capacity of eosinophils and raise the question at what point in time their function is regulated. Similarly, eosinophils from different physical locations display phenotypic and functional diversity. However, it remains unclear whether eosinophil plasticity remains as they develop and travel from the bone marrow to the tissue, in homeostasis or during inflammation. In the tissue, eosinophils of different ages and origin along the inflammatory trajectory may exhibit functional diversity as circumstances change. Herein, we outline the inflammatory time line of allergic airway inflammation from acute, late, adaptive to chronic processes. We summarize the function of the eosinophils in regards to their resident localization and time of recruitment to the lung, in all stages of the inflammatory response. In all, we argue that immunological differences in eosinophils are a function of time and space as the allergic inflammatory response is initiated and resolved.

Ceramide in apoptosis and oxidative stress in allergic inflammation and asthma

BACKGROUND

Nothing is known about the mechanisms by which increased ceramide levels in the lung contribute to allergic responses and asthma severity.

OBJECTIVE

We sought to investigate the functional role of ceramide in mouse models of allergic airway disease that recapitulate the cardinal clinical features of human allergic asthma.

METHODS

Allergic airway disease was induced in mice by repeated intranasal administration of house dust mite or the fungal allergen Alternaria alternata. Processes that can be regulated by ceramide and are important for severity of allergic asthma were correlated with ceramide levels measured by mass spectrometry.

RESULTS

Both allergens induced massive pulmonary apoptosis and also significantly increased reactive oxygen species in the lung. Prevention of increases in lung ceramide levels mitigated allergen-induced apoptosis, reactive oxygen species, and neutrophil infiltration. In contrast, dietary supplementation of the antioxidant α-tocopherol decreased reactive oxygen species but had no significant effects on elevation of ceramide level or apoptosis, indicating that the increases in lung ceramide levels in allergen-challenged mice are not mediated by oxidative stress. Moreover, specific ceramide species were altered in bronchoalveolar lavage fluid from patients with severe asthma compared with in bronchoalveolar lavage fluid from individuals without asthma.

CONCLUSION

Our data suggest that elevation of ceramide level after allergen challenge contributes to the apoptosis, reactive oxygen species generation, and neutrophilic infiltrate that characterize the severe asthmatic phenotype. Ceramide might be the trigger of formation of Creola bodies found in the sputum of patients with severe asthma and could be a biomarker to optimize diagnosis and to monitor and improve clinical outcomes in this disease.

More Than Just a Barrier: The Immune Functions of the Airway Epithelium in Asthma Pathogenesis

Allergic bronchial asthma is a chronic disease of the airways that is characterized by symptoms like respiratory distress, chest tightness, wheezing, productive cough, and acute episodes of broncho-obstruction. This symptom-complex arises on the basis of chronic allergic inflammation of the airway wall. Consequently, the airway epithelium is central to the pathogenesis of this disease, because its multiple abilities directly have an impact on the inflammatory response and thus the formation of the disease. In turn, its structure and functions are markedly impaired by the inflammation. Hence, the airway epithelium represents a sealed, self-cleaning barrier, that prohibits penetration of inhaled allergens, pathogens, and other noxious agents into the body. This barrier is covered with mucus that further contains antimicrobial peptides and antibodies that are either produced or specifically transported by the airway epithelium in order to trap these particles and to remove them from the body by a process called mucociliary clearance. Once this first line of defense of the lung is overcome, airway epithelial cells are the first cells to get in contact with pathogens, to be damaged or infected. Therefore, these cells release a plethora of chemokines and cytokines that not only induce an acute inflammatory reaction but also have an impact on the alignment of the following immune reaction. In case of asthma, all these functions are impaired by the already existing allergic immune response that per se weakens the barrier integrity and self-cleaning abilities of the airway epithelium making it more vulnerable to penetration of allergens as well as of infection by bacteria and viruses. Recent studies indicate that the history of allergy- and pathogen-derived insults can leave some kind of memory in these cells that can be described as imprinting or trained immunity. Thus, the airway epithelium is in the center of processes that lead to formation, progression and acute exacerbation of asthma.

Topical Spilanthol Inhibits MAPK Signaling and Ameliorates Allergic Inflammation in DNCB-Induced Atopic Dermatitis in Mice

Atopic dermatitis (AD) is a recurrent allergic skin disease caused by genetic and environmental factors. Patients with AD may experience immune imbalance, increased levels of mast cells, immunoglobulin (Ig) E and pro-inflammatory factors (Cyclooxygenase, COX-2 and inducible NO synthase, iNOS). While spilanthol (SP) has anti-inflammatory and analgesic activities, its effect on AD remains to be explored. To develop a new means of SP, inflammation-related symptoms of AD were alleviated, and 2,4-dinitrochlorobenzene (DNCB) was used to induce AD-like skin lesions in BALB/c mice. Histopathological analysis was used to examine mast cells and eosinophils infiltration in AD-like skin lesions. The levels of IgE, IgG1 and IgG2a were measured by enzyme-linked immunosorbent assay (ELISA) kits. Western blot was used for analysis of the mitogen-activated protein kinase (MAPK) pathways and COX-2 and iNOS protein expression. Topical SP treatment reduced serum IgE and IgG2a levels and suppressed COX-2 and iNOS expression via blocked mitogen-activated protein kinase (MAPK) pathways in DNCB-induced AD-like lesions. Histopathological examination revealed that SP reduced epidermal thickness and collagen accumulation and inhibited mast cells and eosinophils infiltration into the AD-like lesions skin. These results indicate that SP may protect against AD skin lesions through inhibited MAPK signaling pathways and may diminish the infiltration of inflammatory cells to block allergic inflammation.

Enhanced pause correlates with airway neutrophils and airway-epithelial injury in asthmatic mice treated with dexamethasone

OBJECTIVE

To investigate the correlations among airway inflammation, airway epithelial injury and airway hyperresponsiveness (AHR) in asthmatic mice treated with dexamethasone.

METHODS

Female BALB/c mice were sensitized with intraperitoneal and hypodermic injections of ovalbumin (OVA) and aluminum on days 0, 7 and 14, challenged with OVA starting on day 21 for 10 days, and treated with dexamethasone via intraperitoneal injection starting on day 28 for 3 days. Female C57BL/6 mice were treated intranasally with house dust mite (HDM) on days 1 and 14, challenged intranasally with HDM on days 21, 23, 25, 27 and 29, and treated with sivelestat (a selective neutrophil elastase inhibitor) via intraperitoneal injection after each challenge. Following the final challenge, enhanced pause (Penh) and differential cell counts in the broncho-alveolar lavage fluid were measured and the correlations were analyzed.

RESULTS

Compared with OVA-challenged BALB/c mice, the counterpart mice treated with dexamethasone showed reduced Penh and shedding of airway epithelial cells. In addition, we found that Penh 50 (an indicator of AHR) had positive correlations with airway neutrophils and shedding of airway epithelial cells, but no correlation with eosinophils, lymphocytes or macrophages. Moreover, shedding of airway epithelial cells had positive correlations with airway neutrophils, but no correlation with eosinophils, lymphocytes or macrophages. Further, sivelestat decreased Penh 50 and shed airway-epithelial cells in HDM-challenged C57BL/6 mice.

CONCLUSIONS

Collectively, our findings suggest that airway neutrophils and excessive shedding of airway epithelial cells, but not eosinophils, lymphocytes or macrophages, may be involved in AHR in asthmatic mice treated with dexamethasone.

Montelukast Reduces Serum Levels of Eosinophil-Derived Neurotoxin in Preschool Asthma

Purpose

Several markers for eosinophilic inflammation have been proposed to predict response to asthma treatment. However, definitive criteria for treatment decisions have not yet been established. We investigate a potentially useful relatively non-invasive biomarker, eosinophil-derived neurotoxin (EDN), to predict favorable responses to budesonide or montelukast, common treatment for children with asthma.

Methods

Young children (1 to 6 years old) were enrolled in this randomized, parallel, 2-group, open-label trial. Criteria for eligibility included: 1) being symptomatic during the run-in period; and 2) having a serum EDN (sEDN) level ≥ 53 ng/mL, with positive specific immunoglobulin E to house dust mite. Eligible patients were randomly placed into 2 groups: the BIS group received budesonide inhalation suspension (BIS) 0.5 mg once daily; the MONT group received montelukast 4 mg once daily. Ineligible patients were invited to receive montelukast 4 mg once daily (OBS group). Treatment period was 12 weeks.

Results

Asthma control days increased significantly in the BIS and MONT groups (P < 0.000) over the 12-week study period. There was no significant change in sEDN in the BIS group but there was a significant decrease in the MONT group (P < 0.000). Patients in the OBS group with high EDN levels (< 53 ng/mL) showed a significant decrease due to MONT treatment (P = 0.023). Rescue medication usage significantly decreased in the BIS and MONT groups (P < 0.000).

Conclusions

EDN is a useful relatively non-invasive biomarker for predicting responses to montelukast and budesonide treatment of preschool children with beta2-agonist responsive recurrent wheeze and multiple-trigger wheeze (Trial registry at UMIN Clinical Trials Registry, UMIN000008335).

Pathological Roles of Neutrophil-Mediated Inflammation in Asthma and Its Potential for Therapy as a Target

Asthma is a chronic inflammatory disease that undermines the airways. It is caused by dysfunction of various types of cells, as well as cellular components, and is characterized by recruitment of inflammatory cells, bronchial hyperreactivity, mucus production, and airway remodelling and narrowing. It has commonly been considered that airway inflammation is caused by the Th2 immune response, or eosinophilia, which is a hallmark of bronchial asthma pathogenesis. Some patients display a neutrophil-dominant presentation and are characterized with low (or even absent) Th2 cytokines. In recent years, increasing evidence has also suggested that neutrophils play a key role in the development of certain subtypes of asthma. This review discusses neutrophils in asthma and potentially related targeted therapies.

X-ray-based lung function measurement reveals persistent loss of lung tissue elasticity in mice recovered from allergic airway inflammation

Chronic asthma patients experience difficulties even years after the inciting allergen. Although studies in small animal asthma models have enormously advanced progress in uncovering the mechanisms of inception and development of the disease, little is known about the processes involved in the persistence of asthma symptoms in the absence of allergen exposure. Long-term asthma mouse models have so far been scarce or not been able to reproduce the findings in patients. Here we used a common ovalbumin-induced acute allergic airway inflammation mouse model to study lung function and remodeling after a 4-mo recovery period. We show by X-ray-based lung function measurements that the recovered mice continue to show impaired lung function by displaying significant air trapping compared with controls. High-resolution synchrotron phase-contrast computed tomography of structural alterations and diaphragm motion analysis suggest that these changes in pulmonary function are the result of a pronounced loss in lung elasticity. Histology of lung sections confirmed that this is most likely caused by a decrease in elastic fibers, indicating that remodeling can develop or persist independent of acute inflammation and is closely related to a loss in lung function. Our findings demonstrate that this X-ray-based imaging platform has the potential to comprehensively and noninvasively unravel long-term effects in preclinical mouse models of allergic airway inflammation and thus benefits our understanding of chronic asthma.

Diurnal physiological and immunological responses to a 10-km run in highly trained athletes in an environmentally controlled condition of 6 °C

Purpose

The Clara cell protein CC16, secreted from Clara cells in the lung, is discussed as a potential biomarker for toxic effects on the airways. An increased concentration of CC16 in serum may be caused by increased permeability of the lungs. To investigate the changes in P-CC16 in response to an intense exercise bout performed at different times of day (9 am and 4 pm) of highly trained individuals.

Method

Using a crossover randomized design, 8 runners (mean VO_2max 71 ml kg⁻¹ min⁻¹, SD 6) performed a 10-km time trial run, at 9 am and 4 pm, in an environmental chamber set at 6 °C. Lung function tests and blood sampling occurred at baseline, immediately post and 1 h post time trial.

Result

Diurnal differences (P < 0.05) were found for blood neutrophil and lymphocyte counts; with higher values at 4 pm. P-CC16 was higher at the pre- and post-trial time point at 9 am compared to 4 pm. Lung function was not different between or within trials.

Conclusion

Morning trial in cold condition caused more physiological strain compared to the same trial in the evening. However, this extra stress caused by zeitgebers could be a useful strategy for athletes, coaches, and general population to improve their running performance and protect their health in cold conditions in the long-term plan.

[Role of serum neutrophil elastase determination in the diagnosis of acute exacerbation of asthma in preschool children]

OBJECTIVE

To study the role of serum neutrophil elastase (NE) level in acute exacerbation of asthma in preschool children.

METHODS

A total of 85 preschool children who were diagnosed with asthma between January 2008 and January 2010 were classified into acute exacerbation group (n=44) and non-acute exacerbation group (n=41). Thirty-five children who received physical examination served as the control group. The enzyme-linked immunosorbent assay was used to determine the serum levels of NE and interleukin-8 (IL-8). The receiver operating characteristic (ROC) curve was used for NE evaluation.

RESULTS

Both the acute and non-acute exacerbation groups had higher serum levels of NE and IL-8 than the control group, and the acute exacerbation group had significantly higher serum levels of NE and IL-8 than the non-acute exacerbation group (P<0.05). The serum level of NE was positively correlated with that of IL-8 (r=0.48, P<0.05). With serum NE level >27.73 μg/L as the cut-off value for diagnosing acute exacerbation of asthma, the sensitivity was 65.9%, the specificity was 95.1%, and the area under the ROC curve was 0.87 (P<0.01).

CONCLUSIONS

The determination of serum NE level in preschool children with asthma helps to diagnose the acute exacerbation of asthma.

Systemic signs of neutrophil mobilization during clinically stable periods and during exacerbations in smokers with obstructive pulmonary disease

BACKGROUND

It is still unclear whether signs of neutrophil mobilization in the blood of patients with chronic obstructive pulmonary disease represent true systemic events and how these relate to bacterial colonization in the airways. In this study, we evaluated these issues during clinically stable periods and during exacerbations in smokers with obstructive pulmonary disease and chronic bronchitis (OPD-CB).

METHODS

Over a period of 60 weeks for each subject, blood samples were repeatedly collected from 60 smokers with OPD-CB during clinically stable periods, as well as during and after exacerbations. Myeloperoxidase (MPO) and neutrophil elastase (NE) protein and mRNA, growth of bacteria in sputum, and clinical parameters were analyzed. Ten asymptomatic smokers and ten never-smokers were included as controls.

RESULTS

We found that, during clinically stable periods, neutrophil and NE protein concentrations were increased in smokers with OPD-CB and in the asymptomatic smokers when compared with never-smokers. During exacerbations, neutrophil and MPO protein concentrations were further increased in smokers with OPD-CB, without a detectable increase in the corresponding mRNA during exacerbations. However, MPO and NE protein and mRNA displayed positive correlations. During exacerbations, only increased neutrophil concentrations were associated with growth of bacteria in sputum. Among patients with low transcutaneous oxygen saturation during exacerbations, PaO2 (partial oxygen pressure) correlated with concentrations of MPO and NE protein and neutrophils in a negative manner.

CONCLUSION

There are signs of systemic neutrophil mobilization during clinically stable periods and even more so during exacerbations in chronic obstructive pulmonary disease. In this condition, MPO and NE may share a cellular origin, but its location remains uncertain. Factors other than local bacteria, including hypoxemia, may be important for driving systemic signs of neutrophil mobilization.

Identification criteria of the rare multi-flagellate Lophomonas blattarum: comparison of different staining techniques

Bronchopulmonary lophomoniasis (BPL) is an emerging disease of potential importance. BPL is presented by non-specific clinical picture and is usually accompanied by immunosuppression. Culture of Lophomonas blattarum is difficult and its molecular diagnosis has not yet been developed. Therefore, microscopic examination of respiratory samples, e.g., bronchoalveolar lavage (BAL) or sputum, is the mainstay of BPL diagnosis. Creola bodies and ciliocytophthoria are two forms of bronchial cells which occur in chest diseases with non-specific clinical picture like that of BPL. Both forms could be misrecognized as multi-flagellates because of their motile cilia in the wet mounts and due to shape variability of L. blattarum in stained smears. The aim of the study is to compare different staining techniques for visualizing L. blattarum to improve the recognition and diagnosis of BPL, to distinguish respiratory epithelial cells from L. blattarum and to decide which stain is recommended in suspected cases of BPL. BAL samples from patients which contain L. blattarum, creola bodies, and ciliocytophthoria were collected then wet mounts were examined. The BAL samples were also stained by Papanicolaou (PAP), Giemsa, hematoxylin and eosin (H & E), trichrome, Gram, and Diff-Quik (DQ) stains. The different staining techniques were compared regarding the stain quality. In wet mounts, the ciliary movement was coordinate and synchronous while the flagellar movement was wavy and leaded to active swimming of L. blattarum. In stained slides, bronchial cells were characterized by the presence of basal nucleus and the terminal bar from which the cilia arise. Trichrome was the best stain in demonstration of cellular details of L. blattarum. H & E, PAP, and Giemsa stains showed good quality of stains. Gram and DQ stains showed only pale hues of L. blattarum. We recommended adding Wheatley's trichrome staining to the differential diagnosis workup of cases of non-specific chest infections, especially when BPL is suspected, to avoid overdiagnosis or underdiagnosis of it.

Pediatric allergy and immunology in Japan

The Japanese Society of Pediatric Allergy and Clinical Immunology (JSPACI) was started in 1966 and currently has 3613 members as of August 1, 2012. The number of pediatricians specializing in allergies who have been certified by the Japanese Society of Allergology is 817. Among these, there are 125 training directors and training facilities for allergy and clinical immunology. The JSPACI first published an asthma guideline specific for children in 2000, and this has been revised every 3 yrs, contributing to better control of pediatric asthma. Food allergy management guidelines were first developed in 2005, which have helped to improve the care of food allergy patients. Among 514 pediatric training programs by the Japanese Society of Pediatrics, there are 312 facilities routinely performing oral food challenges. Among these, there were already 53 facilities performing oral immunotherapy at the end of 2011, treating 1400 cases of food allergy. The prevalence of pediatric allergic diseases has increased in Japan over the past 50 yrs. A number of International Study of Asthma and Allergies in Childhood surveys have been conducted in the past at specific times. The prevalence of wheezing among children aged 13-14 yrs in 2002 was 13.0%. Multi-year surveys found a 1.5- to 2-fold increase every 10 yrs until 2002. However, according to the latest data in 2012, asthma prevalence seems to have slightly decreased in Japan. Food allergy mainly associated with infantile atopic eczema among infants younger than 1 yr of age is the most common form as with other developed countries. The estimated food allergy prevalence based on data from several surveys is 5-10% among infants (0-6 yrs) and 1-2% among schoolchildren (6-15 yrs). A variety of patients suffering from primary deficiency syndrome have been actively analyzed. Previously, antibody defects and well-defined syndromes with immunodeficiency were analyzed, but recent research is focusing on not only acquired immune disorders but also on innate immune disorders. In contrast to the widespread use of oral immunotherapy, one immediate issue is to develop and reassess subcutaneous and sublingual immunotherapies for mite and Japanese cedar pollen antigens that have been disused in Japan since the 1990s.

Relationships between IL-17A and macrophages or MUC5AC in eosinophilic chronic rhinosinusitis and proposed pathological significance

Recently, some researchers have reported that macrophages and neutrophils were related to severe asthma. Mucus hypersecretion and persistent airway inflammation result from increased expression of mucin gene (MUC5AC). Eosinophilic chronic rhinosinusitis (ECRS) is considered as intractable rhinosinusitis. From the viewpoint of “one way one disease,” we examined whether ECRS is associated with infiltrating macrophages, neutrophils, their promotive factors, and MUC5AC. We examined 21 nasal polyps with CRS. Each specimen was fixed in 10% phosphate-buffered formalin, embedded in paraffin, processed routinely, and then prepared as semithin sections (3.5 μm). We immunohistochemically observed the macrophages by using CD68, neutrophils by using neutrophil elastase and the promotive factors, monocyte chemotactic protein (MCP) 1, IL-17A, and IL-8, in both ECRS and non-ECRS. The number of macrophages (CD68⁺ cells), IL-17A, and MUC5AC⁺ cells in ECRS were significantly greater than in non-ECRS. The mean number of MCP-1⁺ cells in ECRS was greater than that in non-ECRS, but not significantly. There was a significant correlation in all cases between IL-17A and macrophages or MUC5AC⁺ cells. Neither the numbers of neutrophils (positive cells for neutrophil elastase) nor the IL-8⁺ cells showed any significant differences between ECRS and non-ECRS. Our study suggested that infiltrating macrophages, IL-17A and MUC5AC, as well as eosinophils could have roles in the development of ECRS.

Inhibition of common cold-induced aggravation of childhood asthma by leukotriene receptor antagonists

BACKGROUND

Virus infection is an important risk factor for aggravation of childhood asthma. The objective of this study was to examine the effect of drugs on aggravation of asthma induced by a common cold.

METHODS

Asthma control was examined in a survey of 1,014 Japanese pediatric patients with bronchial asthma. The occurrence of common cold, asthma control, and drugs used for asthma control were investigated using a modified Childhood Asthma Control Test (C-ACT) for patients aged <4 years old and 4 to 11 years old, and an Asthma Control Test (ACT) for patients aged 12 to 15 years old.

RESULTS

The status of asthma control did not differ among the age groups. The prevalence of common cold and aggravation of asthma were significantly higher in patients aged <4 years old. Control of asthma following common cold-induced aggravation was significantly less effective in patients aged <4 years old compared to those aged ≥4 years old. In patients aged <4 years old with a common cold, asthma control was significantly more effective for those treated with leukotriene receptor antagonists (LTRAs) compared to treatment without LTRAs. Asthma control did not differ between patients who did or did not take inhaled corticosteroids or long-acting β2 stimulants.

CONCLUSIONS

These findings showed a high prevalence of common cold in younger patients with childhood asthma and indicated that common cold can induce aggravation of asthma. LTRAs are useful for long-term asthma control in very young patients who develop an asthma attack due to a common cold.

What's new in asthma pathophysiology and immunopathology?

Research on asthma pathophysiology over the past decade has expanded the complex repertoire involved in the pathophysiology of asthma to include inflammatory, immune and structural cells, as well as a wide range of mediators. Studies have identified a role for connective and other mesenchymal tissues involved in airway remodeling. Recent findings have implicated the innate immune response in asthma and have revealed interesting patterns of interaction between the innate and adaptive immune response and the associated complex chronic inflammatory reaction. New immune cell populations have also been added to this repertoire, including Tregs, natural killer T cells and Th17 cells. The role of the eosinophil, a prominent pathological feature in most asthma phenotypes, has also been expanding to include roles such as tissue modifiers and immune regulators via a number of fascinating and hitherto unexplored mechanistic pathways. In addition, new and significant roles have been proposed for airway smooth muscle cells, fibroblasts, epithelial and endothelial cells. Tissue remodeling is now considered an integral element of asthma pathophysiology. Finally, an intricate network of mediators, released from both immune and inflammatory cells, including thymus stromal lymphopoietin and matrix metalloproteinases, have added to the complex milieu of asthma immunity and inflammation. These findings have implications for therapy and the search for novel strategies towards better disease management. Sadly, and perhaps due to the complex nature of asthma, advances in therapeutic discoveries and developments have been limited. Thus, understanding the precise roles played by the numerous dramatis personae in this odyssey, both individually and collectively within the context of asthma pathophysiology, continues to pose new challenges. It is clear that the next stage in this saga is to embark on studies that transcend reductionist approaches to involve system analysis of the complex and multiple variables involved in asthma, including the need to narrow down the phenotypes of this condition based on careful analysis of the organs (lung and airways), cells, mediators and other factors involved in bronchial asthma.

A gender difference in circulating neutrophils in malnourished patients with COPD

Background

Circulating markers of inflammation in chronic obstructive pulmonary disease (COPD) may correlate to disease progression and extrapulmonary complications such as malnourishment. However, surprisingly little is known about gender-related differences for circulating inflammatory markers in COPD.

Purpose

To characterize differences in circulating markers of inflammation in malnourished female and male patients with COPD.

Subjects

Thirty female and 11 male patients with a clinical diagnosis of COPD and malnourishment were examined. A group of control subjects without evidence of COPD was recruited for comparison of some variables.

Methods

Blood samples were drawn, and the following parameters were studied: leukocytes and differential counts, C-reactive protein (CRP), tumor necrosis factor-α, interleukin (IL)-6 and IL-8, myeloperoxidase (MPO), neutrophil elastase (NE), intracellular adhesion molecule-1, vascular endothelial adhesion molecule-1, and E-selectin.

Results

The mean neutrophil concentration was significantly (P = 0.019) higher in female (4.5 × 10⁹/L) than in male patients with COPD (3.5 × 10⁹/L) and significantly higher than in female control subjects (3.1 × 10⁹/L) (P < 0.01, n = 85). The mean CRP values were considerably higher in female (4.9 mg/mL) than in male patients with COPD (1.5 mg/mL), but the difference was not statistically significant (P = 0.20). The mean concentrations of IL-6 and IL-8 tended to be higher in female than in male patients with COPD, but these differences did not reach statistical significance either (P > 0.05). Confounding factors (smoking, medication) could not explain the gender differences noted. The concentrations of MPO and NE displayed a strong correlation (r = 0.89; P < 0.01, n = 41) but revealed no gender differences. The latter was true for concentrations of adhesion molecules as well.

Conclusions

Our study puts forward evidence of a gender-related difference in systemic inflammation in malnourished patients with COPD in terms of circulating neutrophils being more abundant in female patients. Among these female patients, there was also a trend toward an increase in two neutrophil-mobilizing cytokines. New and better-powered studies are warranted to confirm and characterize this potentially important phenomenon in greater detail.

Creola bodies in infancy with respiratory syncytial virus bronchiolitis predict the development of asthma

BACKGROUND

Creola bodies (CrBs) in the sputum are an indicator of respiratory epithelial damage and appear specifically in bronchial asthma. We studied the presence and clinical significance of CrBs in infants with respiratory syncytial virus (RSV) bronchiolitis contributing to the development of asthma.

METHODS

Aspirated sputum samples were collected from 33 infants admitted with acute RSV bronchiolitis. The samples were then examined for the presence (or absence) of CrBs and classified into the RSV-CrB group and RSV-non-CrB group. Eosinophil cationic protein (ECP) and neutrophil elastase (NE) concentrations in the sputum were compared between the two groups. History of wheeze and asthma was collected at 2 years and 5 years after their discharge from hospital.

RESULTS

CrBs were detected in 23 of the 33 subjects (69.7%). No significant difference in the ECP and the NE concentration were observed between the RSV-CrB group and RSV-non-CrB group. A significant relationship was observed between CrBs detected with RSV bronchiolitis and the development of recurrent wheezing and asthma (after 2 years: relative risk [RR], 3.09; p = 0.002; after 5 years: RR 7.00; p = 0.019).

CONCLUSIONS

These findings suggest that a high rate of CrBs in the sputum is present in infants with RSV bronchiolitis, and notably the CrBs are associated with the progression to recurrent wheezing and asthma.

Resolution of cell-mediated airways diseases

"Inflammation resolution" has of late become a topical research area. Activation of resolution phase mechanisms, involving select post-transcriptional regulons, transcription factors, 'autacoids', and cell phenotypes, is now considered to resolve inflammatory diseases. Critical to this discourse on resolution is the elimination of inflammatory cells through apoptosis and phagocytosis. For major inflammatory diseases such as asthma and COPD we propose an alternative path to apoptosis for cell elimination. We argue that transepithelial migration of airway wall leukocytes, followed by mucociliary clearance, efficiently and non-injuriously eliminates pro-inflammatory cells from diseased airway tissues. First, it seems clear that numerous infiltrated granulocytes and lymphocytes can be speedily transmitted into the airway lumen without harming the epithelial barrier. Then there are a wide range of 'unexpected' findings demonstrating that clinical improvement of asthma and COPD is not only associated with decreasing numbers of airway wall inflammatory cells but also with increasing numbers of these cells in the airway lumen. Finally, effects of inhibition of transepithelial migration support the present hypothesis. Airway inflammatory processes have thus been much aggravated when transepithelial exit of leukocytes has been inhibited. In conclusion, the present hypothesis highlights risks involved in drug-induced inhibition of transepithelial migration of airway wall leukocytes. It helps interpretation of common airway lumen data, and suggests approaches to treat cell-mediated airway inflammation.

Reduction of collagen VII anchoring fibrils in the airway basement membrane zone of infant rhesus monkeys exposed to house dust mite

Collagen VII anchoring fibrils in the basement membrane zone (BMZ) are part of a supracellular anchoring network that attaches the epithelium to the BMZ. Sloughing of airway epithelium in asthmatics (creola bodies) is a pathology associated with the supracellular anchoring network. In a rhesus monkey model of house dust mite (HDM)-induced allergic asthma, we found increased deposition of collagen I in the BMZ. In this study, we determine whether HDM also affected deposition of collagen VII in the BMZ. In the developing airway of rhesus monkeys, the width of collagen VII anchoring fibrils in the BMZ was 0.02 +/- 0.04 microm at 1 mo of age. At 6 mo the width had increased to 1.28 +/- 0.34 microm and at 12 mo 2.15 +/- 0.13 microm. In animals treated with HDM, we found a 42.2% reduction in the width of collagen VII layer in the BMZ at 6 mo (0.74 +/- 0.15 microm; P < 0.05). During recovery, the rate of collagen VII deposition returned to normal. However, the amount of collagen VII lost was not recovered after 6 mo. We concluded that normal development of the collagen VII attachment between the epithelium and BMZ occurs in coordination with development of the BMZ. However, in HDM-treated animals, the collagen VII attachment with the epithelium was significantly reduced. Such a reduction in collagen VII may weaken the supracellular anchoring network and be associated with sloughing of the epithelium and formation of creola bodies in asthmatics.

Decreased fibronectin production significantly contributes to dysregulated repair of asthmatic epithelium

RATIONALE

Damage to airway epithelium is followed by deposition of extracellular matrix (ECM) and migration of adjacent epithelial cells. We have shown that epithelial cells from children with asthma fail to heal a wound in vitro.

OBJECTIVES

To determine whether dysregulated ECM production by the epithelium plays a role in aberrant repair in asthma.

METHODS

Airway epithelial cells (AEC) from children with asthma (n = 36), healthy atopic control subjects (n = 23), and healthy nonatopic control subjects (n = 53) were investigated by microarray, gene expression and silencing, transcript regulation analysis, and ability to close mechanical wounds.

MEASUREMENTS AND MAIN RESULTS

Time to repair a mechanical wound in vitro by AEC from healthy and atopic children was not significantly different and both were faster than AEC from children with asthma. Microarray analysis revealed differential expression of multiple gene sets associated with repair and remodeling in asthmatic AEC. Fibronectin (FN) was the only ECM component whose expression was significantly lower in asthmatic AEC. Expression differences were verified by quantitative polymerase chain reaction and ELISA, and reduced FN expression persisted in asthmatic cells over passage. Silencing of FN expression in nonasthmatic AEC inhibited wound repair, whereas addition of FN to asthmatic AEC restored reparative capacity. Asthmatic AEC failed to synthesize FN in response to wounding or cytokine/growth factor stimulation. Exposure to 5', 2'deoxyazacytidine had no effect on FN expression and subsequent analysis of the FN promoter did not show evidence of DNA methylation.

CONCLUSIONS

These data show that the reduced capacity of asthmatic epithelial cells to secrete FN is an important contributor to the dysregulated AEC repair observed in these cells.

Asthma in infants and children

Asthma is the most common chronic illness in childhood and represents a significant burden to health care and educational systems. Between one quarter and two thirds of childhood asthma cases persist into adulthood. Childhood asthma may be particularly difficult to diagnose because of the high prevalence of episodic wheezing and cough in childhood illnesses such as upper respiratory tract infections. National and worldwide guidelines for the management of asthma in children are continually being updated. These guidelines recommend first establishing a diagnosis and assessing the severity of disease, initiating pharmacologic therapy based on symptoms and lung function, and adjusting doses and agents as required based on the level of asthma control. Inhaled corticosteroids are the cornerstone of long-term asthma management in children of all ages. Recent research efforts have focused on ways to improve inhalant drug delivery to the lungs and minimize oral and systemic bioavailability so as to improve the therapeutic benefit:risk ratio.

Presence of eosinophils in nasal secretion during acute respiratory tract infection in young children predicts subsequent wheezing within two months

BACKGROUND

In young children with wheezing or bronchiolitis, especially with respiratory syncitial virus, blood eosinophilia and a high eosinophil cationic protein level in nasal secretions predicts subsequent wheezing in later childhood. However, whether eosinophil activation results from virus-induced inflammation or local eosinophilia per se precedes the onset of wheezing remains unknown. In the present study, we examined the association between the presence of nasal eosinophils during respiratory tract infection (RTI) and subsequent wheezing in young children.

METHODS

A total of 35 young children less than 3 years of age who visited our outpatient clinic with rhinorrhea between April and July 2004 were enrolled in this prospective cohort study. Subjects who were given diagnoses of allergic rhinitis were excluded. In all the subjects, the presence of eosinophils in nasal secretions was determined. The subjects were followed, and the cumulative incidences of wheezing during the subsequent 2- and 12-month periods were examined.

RESULTS

According to a logistic regression analysis adjusted for age, sex, family history, allergies, and wheezing at entry, young children with nasal eosinophil infiltration during acute RTI had a significantly higher risk of wheezing during the subsequent 2 months, compared with those without nasal eosinophil infiltration (adjusted odds ratio, 27.618, p = 0.016).

CONCLUSIONS

Our findings not only suggest that nasal eosinophil testing may serve as a convenient clinical marker for identifying young children at risk for subsequent wheezing, but also shed new light on the role of eosinophils in the onset of wheezing in young children.

Allergy and the lung

Among the 'allergic' conditions involving the lung, asthma is the more frequent and the most extensively investigated, although asthma itself may be caused by different disorders. The triggering event in allergic subjects is the reaction allergen-specific immunoglobulin E (IgE) that activates mast cells and initiates a complex and redundant inflammatory process, where cells, cytokines and adhesion molecules are involved at different stages. In fact, mucosal eosinophilic inflammation is one of the distinctive features of asthma and the particular T helper type 2 (Th2) phenotype of allergic patients favours it. In general, the clinical severity of asthma correlates well with the degree of inflammation. None the less, other phenomena such as non-specific bronchial hyperresponsiveness and remodelling intervene in the pathophysiology of allergic asthma. These phenomena are only partially inflammation-related. In particular, the remodelling of the bronchial wall seems to start very early in life and also seems to be a distinctive histological feature of the asthmatic bronchus. The recent introduction of biological treatments (monoclonal antibodies) has allowed elucidation of some of the pathogenic features of allergic asthma.

Neutrophil Proteases Activate Eosinophil Function in vitro

BACKGROUND

Recent evidence suggests that both neutrophilic and eosinophilic inflammation persist in the airways of patients with severe asthma. Mechanisms for interaction between neutrophils and eosinophils are still to be understood. Since eosinophils express protease-activated receptor 2, neutrophil-derived serine proteases may activate eosinophils.

OBJECTIVE

We investigated the effect of neutrophil serine proteases on eosinophil effector functions.

METHODS

Peripheral blood eosinophils were stimulated with elastase, cathepsin G and proteinase 3. Superoxide generation was quantitated with the cytochrome C reduction method. A panel of cytokines and chemokines in the culture supernatants were measured with a multiplex beads array system. Effects of an elastase inhibitor, sivelestat, and a serine protease inhibitor, PMSF, on the protease-induced reactions were also tested.

RESULTS

Neutrophil proteases significantly induced superoxide production from eosinophils. Elastase was the most potent among them. Sivelestat and PMSF inhibited the reaction. The proteases induced production of IL-6, IL-8, TNF-alpha and GRO-alpha, that have a possible connection with neutrophilic inflammation.

CONCLUSION

Neutrophil proteases activate eosinophils to produce superoxide, proinflammatory cytokines and neutrophilotactic chemokines and may further aggravate airway inflammation in patients with severe asthma.

Viral infection in asthma

In bronchial asthma, respiratory virus infection involves several issues: 1) respiratory virus infection in infancy is a risk factor for, and may predispose to, the development of asthma later in life; 2) respiratory virus infection is associated with the acute exacerbation of bronchial asthma; and, 3) glucocorticosteroids (GC) are not adequate for controlling asthma-related symptoms upon respiratory virus infection. Various cells, inflammatory mediators and cytokines participate in the production of airway inflammation upon respiratory virus infection. Bronchial epithelial cells are a site of infection and replication of respiratory virus. They actively participate in the production of airway inflammation: 1) they produce various proinflammatory cytokines, chemokines and mediators; and, 2) they undergo apoptosis, thereby impairing the repair process. It is therefore important to understand the role of bronchial epithelial cells in the pathophysiology of bronchial asthma. In this review, the interaction between viral infection and asthma is discussed to elucidate the role of bronchial epithelial cells in viral infection.

Effects of triterpenoid-rich extracts of Ganoderma tsugae on airway hyperreactivity and Th2 responses in vivo

BACKGROUND

Airway inflammation and Th2 responses play central roles in allergic asthma. We have previously reported that Ganoderma tsugae supplementation could attenuate airway inflammation in the murine model. Since it remains unclear which part of the G. tsugae exerts this effect on allergic asthma in vivo, this study was meant to investigate if triterpenoid extracts have anti-inflammatory effects on airway responses and regulatory effects on Th2 responses.

METHODS

BALB/c mice sensitized intraperitoneally and challenged with ovalbumin (OVA) were treated with either triterpenoid-rich extracts (TRE) of G. tsugae or prednisolone for 2 weeks. The effects of TRE on bronchial airway hyperresponsiveness (AHR), airway inflammation, serum antigen-specific antibody levels, and cytokine secretions from splenocytes were evaluated.

RESULTS

TRE supplementation significantly decreased AHR and reduced the total infiltrating leukocytes and eosinophils, as well as the levels of inflammatory mediators, such as interleukin (IL)-4, IL-5 and eotaxin in bronchoalveolar lavage fluid when compared with those of the control group. Lung histology also showed less cell recruitment and lung damage. TRE supplements suppressed IL-5 secretions from OVA-stimulated splenocytes, but did not affect the cell number of splenocytes, which was also reduced by prednisolone. Although OVA-specific immunoglobulin E levels were not significantly different among the groups, a lower level of OVA-specific immunoglobulin G1, another Th2-related antibody, was found in TRE and prednisolone treatment.

CONCLUSIONS

TRE of G. tsugae exert anti-inflammatory effects on airway responses and attenuate Th2 responses without the overall immunosuppression effects in allergic murine models of asthma.