Atopy may be an important determinant of subepithelial fibrosis in subjects with asymptomatic airway hyperresponsiveness

Serum YKL-40 levels may help distinguish exacerbation of post-infectious bronchiolitis obliterans from acute bronchiolitis in young children

Children with post-infectious bronchiolitis obliterans (PIBO) are frequently hospitalized with acute exacerbation, but clinical differentiation of PIBO exacerbation from acute bronchiolitis is often challenging, which may result in treatment delay and chronic lung function impairment. We aimed to examine whether serum YKL-40 and growth factors could be markers for PIBO exacerbation. Thirty-seven children admitted with acute exacerbation of PIBO were enrolled and studied retrospectively. Diagnosis of PIBO was based on clinical history of acute respiratory infection followed by persistent airway obstruction and characteristic findings in high-resolution computed tomography. Serum levels of YKL-40, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1, and platelet-derived growth factor (PDGF)-BB were measured on admission. The biomarkers were also examined in children admitted with acute bronchiolitis serving as positive controls (N = 30) and in age-matched controls (N = 20). Only YKL-40 levels were found to be significantly higher in PIBO patients with exacerbation compared with that in bronchiolitis patients and showed a positive correlation with the severity of disease before diagnosis of PIBO.

CONCLUSION

Our results suggest that measuring serum YKL-40 levels might help distinguish exacerbation of PIBO from acute bronchiolitis in young children. What is Known: • The children with post-infectious BO (PIBO) usually have recurrent wheezing and need frequent hospitalization due to acute exacerbation during the first disease years. • Clinical differentiation of PIBO exacerbation from acute bronchiolitis in young children is often challenging, which may result in treatment delay and chronic lung function impairment. What is New: • Measuring serum YKL-40 levels might help distinguish exacerbation of PIBO from acute bronchiolitis in young children.

Less small airway dysfunction in asymptomatic bronchial hyperresponsiveness than in asthma

BACKGROUND

Bronchial hyperresponsiveness (BHR) can be present in subjects without any respiratory symptoms. Little is known about the role of the small airways in asymptomatic subjects with BHR.

METHODS

We investigated small airway function assessed by spirometry and impulse oscillometry, as well as Borg dyspnea scores at baseline and during a methacholine provocation test in 15 subjects with asymptomatic BHR, 15 asthma patients, and 15 healthy controls.

RESULTS

At baseline, small airway function (R5 -R20 and X5 ) was comparable between subjects with asymptomatic BHR and healthy controls, whereas asthma patients showed small airway dysfunction as reflected by higher R5 -R20 and lower X5 values. During methacholine provocation, small airway dysfunction was more severe in asthma patients than in subjects with asymptomatic BHR. Interestingly, a higher increase in small airway dysfunction during methacholine provocation was associated with a higher increase in Borg dyspnea scores in subjects with asymptomatic BHR, but not in asthma patients.

CONCLUSION

Subjects with asymptomatic BHR may experience fewer symptoms in daily life because they have less small airway dysfunction.

Antigen-induced airway hyperresponsiveness in absence of broncho-obstruction in sensitized guinea pigs

BACKGROUND

Airway obstruction after antigen challenge is not always observed in patients with allergic asthma, even if they develop hyperresponsiveness. A similar event is observed in our guinea pig model of allergic asthma. Our aim was to study this phenomenon.

METHODS

Sensitized guinea pigs were challenged with ovalbumin (OVA) 3 times every 10 days. Animals were divided into 2 groups: (1) Guinea pigs exhibiting airway obstruction after antigen challenge (R = responders), and (2) guinea pigs lacking airway obstruction response (NR = nonresponders). After the third antigen challenge, antigen-induced airway hyperresponsiveness (AI-AHR), serum OVA-specific immunoglobulins, bronchoalveolar lavage fluid (BALF) inflammatory cells, histamine, cysteinyl leukotrienes and thromboxane A2 (TxA2) BALF levels, and in vitro tracheal contraction induced by contractile mediators and OVA were evaluated.

RESULTS

R group consistently displayed a transient antigen-induced airway obstruction (AI-AO) as well as AI-AHR, high T×A2, histamine, OVA-IgG1, OVA-IgE and OVA-IgA levels, and intense granulocyte infiltration. NR group displayed no AI-AO and no changes in BALF measurements; nevertheless, AI-AHR and elevated OVA-IgG1 and OVA-IgA levels were observed. In all groups, histamine, TxA2 and leukotriene D4 induced a similar contraction. Tracheal OVA-induced contraction was observed only in R group. AI-AHR magnitude showed a direct association with OVA-IgG1 and OVA-IgA levels. The extent of AI-AO correlated directly with OVA-IgE and inversely with OVA-IgA levels.

CONCLUSIONS

Our data suggest that TxA2 and histamine participate in AI-AO likely through an IgE mechanism. AI-AHR might occur independently of AI-AO, contractile mediators release, and airway inflammatory cell infiltration, but IgA and IgG1 seem to be involved.

A brief history of asthma and its mechanisms to modern concepts of disease pathogenesis

The original concept of asthma being primarily a disease of airways smooth muscle drove the development of bronchodilator drugs. However when it was realised that airway inflammation underpinned the disordered airway function, this gave way to the development of controller therapies such as inhaled cromones and corticosteroids. More recently the discovery of complex interconnecting cytokine and chemokine networks has stimulated the development of biologics with varying success. With the recognition that airway wall "remodelling" is present early in asthma inception and is in part driven by aberrant epithelial-mesenchymal communication both genetic and environmental factors beyond allergen exposure such as virus infection and air pollution are being seen as being increasingly important not only in asthma exacerbations but in the origins of asthma and its evolution into different sub-phenotypes. This brings us round full circle to once again considering that the origins of asthma lie in defects in the formed elements of the airway; the epithelium, smooth muscle, and vasculature. Over the last 25 years Professor You Young Kim has engaged in the exciting discovery science of allergy and asthma and has made an enormous contribution in bringing Korea to the forefront of disease management and research, a position that both he and his colleagues can justly be proud of.

Clinical characteristics according to sensitized allergens in adult korean patients with bronchial asthma

Purpose

Allergic sensitization is a risk factor for the development of bronchial asthma. This study was conducted to investigate clinical manifestations according to sensitized allergens in adult Korean patients with bronchial asthma.

Methods

In total, 523 adult patients who were diagnosed with bronchial asthma between March 2002 and March 2008 were included in the study. All patients underwent skin prick tests for approximately 45 allergens or a specific IgE test. Sensitized allergens were grouped into the following categories: house dust mites, fungus, pollen, and animal dander. Atopy was defined as a positive skin prick test response or the presence of a specific IgE to one or more allergens.

Results

Of the 523 patients, 295 (56%) were sensitized to one or more allergens. A younger median age, greater proportion of males, higher eosinophil counts, and higher total IgE levels were observed in the atopic asthma group compared to the non-atopic asthma group. The PC20 value was negatively correlated with eosinophil counts and total IgE in the atopic asthma group. In the subgroup analysis, patients sensitized to Cladosporium showed poorer pulmonary function and a higher response to bronchodilators. In addition, patients sensitized to Alternaria showed severer bronchial hyperresponsiveness than non-atopic patients with asthma. Finally, a gradual increase in the number of sensitized allergens was noted with increasing age, eosinophil counts, and total IgE levels.

Conclusions

We suggest the need for identifying the existence of atopy and exact offending allergens at the time of asthma diagnosis, since significant differences in sex, age, blood test results, and lung function were observed according to atopy and sensitized allergens.