Phenotypic differences between asymptomatic airway hyperresponsiveness and remission of asthma

Accelerated decline in lung function in adults with a history of remitted childhood asthma

AIM

A significant number of children with asthma show remission in adulthood. Although these adults are often diagnosed with chronic obstructive pulmonary disease in later life, the effect of clinically remitted childhood asthma on the decline in lung function during adulthood is uncertain. We examined whether clinical remission of childhood asthma was associated with an accelerated decline in lung function in apparently non-asthmatic adults.

METHODS

Here, 3584 participants (mean age, 48.1 years; range, 35-65 years) who did not have adulthood asthma and other lung diseases and had normal lung function at the baseline visit were included. They were categorised as follows: those with remitted childhood asthma (n=121) and healthy controls (n=3463) according to their self-reported childhood asthma history. Spirometry was performed at baseline and follow-up visits.

RESULTS

The mean follow-up time was 5.3 years. Multivariate regression analysis showed that remitted childhood asthma and smoking were independently associated with a rapid decline in forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC). Besides, smoking was an independent predictor of a rapid decline in the FEV₁/FVC. The annual decline in FEV₁ and FVC was significantly greater in participants with remitted childhood asthma than in healthy controls, and the differences remained significant after adjusting for the propensity score.

CONCLUSION

A history of clinically remitted childhood asthma is an independent risk factor for accelerated decline in lung function in adults. Remitted childhood asthma and smoking may additively accelerate the development of obstructive lung disease.

Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults

BACKGROUND AND OBJECTIVE

While adult asthma has been shown to be a risk factor for COPD, the effect of remitted childhood asthma on adult lung function has not been clarified. The aim of this study was to examine whether remitted childhood asthma is a risk factor for airflow obstruction in a middle-aged general population.

METHODS

A total of 9896 participants (range: 35-60 years) from five healthcare centres were included in the study. The participants were classified into four categories based on the presence or absence of physician-diagnosed childhood/adulthood asthma and asthma symptoms as follows: healthy controls (n = 9154), remitted childhood asthma (n = 287), adulthood-onset asthma (n = 354) and childhood-adulthood asthma (n = 101).

RESULTS

The prevalence of respiratory symptoms was similar in both the participants with remitted childhood asthma and healthy controls. The prevalence of airflow obstruction (forced expiratory volume in 1 s (FEV₁ )/forced vital capacity (FVC) < 0.7) was significantly higher in the participants with remitted childhood asthma, those with adult-onset asthma and those with childhood-adulthood asthma (5.2%, 14.4% and 16.8%, respectively) compared with healthy controls (2.2%). Multivariate logistic regression showed that remitted childhood asthma was independently associated with airflow obstruction. Among the participants with remitted childhood asthma, ever-smokers had significantly lower FEV₁ /FVC than never-smokers.

CONCLUSION

Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults. Smoking and remitted childhood asthma may be additive factors for the development of airflow obstruction.

Potential role of pentosidine on susceptibility to small airway closure in elderly and smoking asthma

BACKGROUND

Small airway closure in asthma is determined by a complex interaction of structural and functional characteristics including lung elastic recoil. Recently, we determined that loss of elastic recoil might be attributable to pentosidine level in the airways. This study was designed to investigate the influences of aging and smoking on small airway closure in asthma.

METHODS

Sixty-one patients with asthma (20 non-smoking young adult, 23 non-smoking elderly, and 18 smoking young adult) and 36 control subjects (12 non-smoking young adult, 11 non-smoking elderly, and 13 smoking young adult) were included. We assessed airway responses during methacholine provocation and calculated the closing index. In addition, we measured pentosidine levels in induced sputum from all study subjects.

RESULTS

Pentosidine levels in induced sputum were markedly higher in asthmatic patients than in controls. In control subjects, the intergroup differences in pentosidine level among 3 subgroups were significant. Similarly, pentosidine levels were significantly higher in non-smoking elderly and smoking young adult asthmatics than in non-smoking young adult asthmatics. There was no significant difference in pentosidine levels between non-smoking elderly and smoking young adult asthmatics. The closing index was also significantly higher in non-smoking elderly and smoking young adult asthmatics than in non-smoking young adult asthmatics. Moreover, pentosidine levels in non-smoking elderly and smoking young adult asthmatics were closely correlated with closing index.

CONCLUSIONS

We determined the correlation of pentosidine level with susceptibility to small airway closure in elderly and smoking asthmatics. Our results might facilitate the understanding of elderly and smoking asthma.

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.

Transforming growth factor-beta1 and IL-13 response to allergen predict steroid needs in asthmatic children

BACKGROUND

The remission of asthma, which is induced during specific immunotherapy (SIT) or appears spontaneously in children is not completely understood and predictors of this phenomenon are still undefined.

OBJECTIVE

To assess CD4(+)CD25(+)Foxp3(+) Treg cells and cytokine/proliferation response to allergen-specific stimulation of PBMC as predictors of steroid sparing effect of SIT and steroid dosage needs without SIT during 5 years of follow-up in asthmatic children.

METHODS

This is a 5-year long study of 32 asthmatic children, sensitive only to house dust mite (HDM). Eighteen children who had completed 5 years of HDM SIT - SIT group, and 14 children without SIT as a control group were studied. All patients had baseline clinical/immunological assessment; before and after observation the minimum effective ICS dose was defined and lung function was measured.

RESULTS

In children from SIT group minimum effective ICS dose was reduced more than in children from control group (median reduction 65% vs. 0%; p<0.001). Among patients in control group asthma severity was reduced after 5 years of observation in those who had at baseline higher TGF-beta1 and lower IL-13 answer to allergen stimulation of PBMC. Better response to 5 years immunotherapy was observed in those who had at baseline higher TGF-beta1 and lower proliferation answer to allergen stimulation of PBMC.

CONCLUSION

Similar processes may decide on both, SIT-induced and spontaneously appearing, reduction in asthma severity. Immunotherapy was much more effective than pharmacotherapy in our study. IL-13 overproduction may impede reduction of disease severity in asthmatic children independently from TGF-beta pathway.

Association of airway pentosidine levels with bronchodilator response mediated by salbutamol administration in asthmatic patients

BACKGROUND

Recently, increased levels of pentosidine, an intermolecular cross-linking type of advanced glycation end products, are observed in the airways of asthmatic patients. This study was designed to determine whether differences in bronchodilator response among individuals with asthma are attributable to pentosidine levels in their airways.

METHODS

Fifty-six asthmatic patients (21 with airway obstruction, 35 without airway obstruction) and 10 normal controls were included in this study. For asthmatic patients, we evaluated the spontaneous reversibility of airway obstruction or the reversibility that can be obtained after methacholine provocation. And we also measured pentosidine levels and percentage of sputum eosinophils in induced sputum, and exhaled nitric oxide (NO) levels.

RESULTS

The pentosidine levels did not significantly differ between the two asthmatic subgroups with and without airway obstruction. In asthmatic patients without airway obstruction, airway hyperresponsiveness to methacholine (PC20 methacholine) was significantly correlated with sputum eosinophils and exhaled NO levels. In contrast, PC20 methacholine was not significantly correlated with pentosidine levels. In asthmatic patients with or without airway obstruction, bronchodilator response was not significantly correlated with sputum eosinophils and exhaled NO levels. However, bronchodilator response was closely correlated with pentosidine levels (asthmatics without airway obstruction: r = -0.54, p = 0.002; asthmatics with airway obstruction: r = -0.48, p = 0.03).

CONCLUSIONS

Our results showed that pentosidine might be a potential biomarker reflecting the reduced bronchodilator response in asthma. This study will provide new insights into the mechanisms underlying persistent airway obstruction.

Characteristics of young atopic adults with self-reported past wheeze and airway hyperresponsiveness

BACKGROUND

The present study aimed to illustrate clinical characteristics of spirometric measures and allergy sensitisation among young atopic adults who reported wheezing episodes before adulthood but were not diagnosed with asthma by physicians and have no current wheeze symptoms (self-reported past-wheezers), especially those who exhibited airway hyperresponsiveness (AHR).

METHODS

Fifty self-reported past-wheezers were divided into two groups according to AHR to methacholine. Spirometric functions and blood atopic parameters were compared in these groups with those in 25 age-matched atopic adults with a history of childhood asthma diagnosed by specialists but have no current wheeze symptoms (past-asthmatics) and in 60 counterparts without a previous and current wheezing episode (never-wheezers).

RESULTS

Twenty-one of the 50 past-wheezers exhibited AHR (PC(20) < 8 mg/ml). Levels of spirometric function and allergic sensitization in both past-wheezer groups were intermediate between those in never-wheezers and past-asthmatics. Lower FEV(1) and FEF(25-75) values (% predicted) were observed in self-reported past-wheezers with AHR relative to those without AHR. More blood eosinophils and higher serum levels of total IgE and IgE specific to house dust mites were observed in self-reported past-wheezers with AHR relative to those without AHR.

CONCLUSIONS

Our findings raise the possibility that self-reported past-wheezers with AHR might form a distinct subgroup with features similar to past-asthmatics, which is one of the risk groups for adult asthma.