Steroid-naive adolescents with mild intermittent allergic asthma have airway hyperresponsiveness and elevated exhaled nitric oxide levels

Mild asthma is not mild: risk factors and predictive biomarkers for severe acute exacerbations and progression in mild asthma

INTRODUCTION

Asthma is a common chronic respiratory disease characterized by chronic airway inflammation, airway hyperresponsiveness, reversible airflow limitation, and airway remodeling. Mild asthma is the most common type of asthma, but it is the most neglected. Sometimes mild asthma can lead to acute severe exacerbations or even death.

AREAS COVERED

This article reviews the epidemiology, risk factors, and possible predictors of acute severe exacerbations and disease progression in mild asthma to improve the understanding of mild asthma and its severe acute exacerbations and progression.

EXPERT OPINION

There is a necessity to improve asthma patient categorization and redefine mild asthma's concept to heighten patient and physician attention. Identifying mild asthma patients that are highly vulnerable to severe acute exacerbations and researching the mechanisms are future prioritizations.

Questions in Mild Asthma: An Official American Thoracic Society Research Statement

Background: Patients with mild asthma are believed to represent the majority of patients with asthma. Disease-associated risks such as exacerbations, lung function decline, and death have been understudied in this patient population. There have been no prior efforts from major societies to describe research needs in mild asthma. Methods: A multidisciplinary, diverse group of 24 international experts reviewed the literature, identified knowledge gaps, and provided research recommendations relating to mild asthma definition, pathophysiology, and management across all age groups. Research needs were also investigated from a patient perspective, generated in conjunction with patients with asthma, caregivers, and stakeholders. Of note, this project is not a systematic review of the evidence and is not a clinical practice guideline. Results: There are multiple unmet needs in research on mild asthma driven by large knowledge gaps in all areas. Specifically, there is an immediate need for a robust mild asthma definition and an improved understanding of its pathophysiology and management strategies across all age groups. Future research must factor in patient perspectives. Conclusions: Despite significant advances in severe asthma, there remain innumerable research areas requiring urgent attention in mild asthma. An important first step is to determine a better definition that will accurately reflect the heterogeneity and risks noted in this group. This research statement highlights the topics of research that are of the highest priority. Furthermore, it firmly advocates the need for engagement with patient groups and for more support for research in this field.

Correlation between fractional exhaled nitric oxide and Asthma Control Test score and spirometry parameters in on-treatment-asthmatics in Ho Chi Minh City

Background

Although fractional exhaled nitric oxide (FeNO) is a reliable and easily applied marker of airway inflammation in asthma, the relationship between FeNO and indicators of asthma control [Asthma Control Test (ACT) score] and/or severity (spirometry parameters) remains unclear. This study aims to determine possible correlations between FeNO and ACT score; and between FeNO and spirometry parameters.

Methods

A cross-sectional study with convenience sampling was conducted among ambulatory patients in the Asthma & COPD clinic at the University Medical Center, Ho Chi Minh City from March 2016 to March 2017. Using measurement of FeNO, the ACT questionnaire and a spirometry test, correlations were determined between FeNO and the ACT score and spirometry parameters.

Results

Four hundred and ten asthmatic patients (mean age 42 years; 65% female) were included and analyzed; their mean time since onset of asthma was 9.5 years. All patients were treated following step 2 to 4 of GINA guidelines. Mean (SD) FeNO was 29.5 (24.4) parts per billion (ppb) and mean (SD) ACT score was 20.5 (40). A significant difference in FeNO values was found among the three groups with different asthma control levels categorized according to the ACT score (P=0.001) but was not found among the three groups with different asthma treatment levels (P=0.425). FeNO was significantly inversely correlated with the ACT score (Spearman’s r =−0.224, P<0.001) and with spirometry parameters indicate airway obstruction such as predicted FEV1, FEV1/FVC, predicted PEF and predicted FEF25–75% with Spearman’s r were −0.187; −0.143; −0.091 and −0.195, respectively (all P<0.05), whereas no correlation between FeNO and FVC—an indicator of airway restriction—was found.

Conclusions

In these asthmatic patients in Vietnam, an inverse correlation was found between FeNO and the ACT score and between FeNO and spirometry indicators of airway obstruction. Therefore, FeNO may be a useful tool in asthma management.

Treat to target approach for asthma

Recognition that about half of asthma deaths might be preventable if recommended guidelines are followed suggests that better implementation of established management strategies is needed. However, to achieve a further substantive reduction in asthma mortality, novel strategies will also be required. It is well established that asthma is a disease of chronic inflammation, with episodes of worsening inflammation associated with increased symptoms and/or exacerbations; however, current guidelines paradoxically recommend that initial treatment is only symptomatic, rather than directed at the underlying inflammatory mechanism. The "Treat to target" (TTT) approach has become a popular concept in the medical management of several common chronic conditions, including rheumatoid arthritis (RA), diabetes, hypertension and hyperlipidemia. For example, as part of a TTT approach, rheumatologists recommend methotrexate for RA with onset within 6 months. Applying the TTT approach to asthma, the primary target could be clinical remission and the primary goals as follows: eliminate symptoms and exacerbation risk; prevent airway remodeling; and normalize lung function. To construct a TTT algorithm for chronic asthma, the proposal is to eradicate short-acting β2-agonists (SABA) at all asthma severity levels and replace SABA with "Anti-Inflammatory Reliever Therapy" (AIR), using inhaled corticosteroids (ICS)/SABA or ICS/formoterol. For individuals with equal to or less than 12 months' history of symptoms, fewer than two symptoms per month, no exacerbations in the last 12 months and normal lung function, the recommendation is early initiation of ICS/SABA or ICS/formoterol as AIR.

Small airway impairment and bronchial hyperresponsiveness in asthma onset

Purpose

Our study tried to find a relationship between baseline FEF_25-75% and airway hyperresponsiveness (AHR) and whether a greater FEF_25-75% impairment may be a marker of a more severe hyperresponsiveness in subjects with normal FEV1 and FEV1/FVC and suggestive asthma symptoms. Besides, we tried to asses a FEF_25-75% cut-off value to identify hyper-reactive subjects.

Methods

4,172 subjects (2,042 M; mean age: 38.3±14.9; mean FEV1 % predicted: 100.5±12.7 and FEV1/FVC: 85.4±6.8) were examined after performing a methacholine (Mch) test. All subjects reported a symptom onset within 3 years before the test. Subjects with PD20<400 or >400 µg were arbitrarily considered affected by moderate/severe and borderline AHR, respectively.

Results

PD20 values were 213 (IQR:86-557), 340 (IQR:157-872) and 433 (IQR:196-1032) µg in subjects with baseline FEF_25-75≤50%, FEF_25-75 between 50 and 70% and FEF_25-75>70% respectively (P<0.0001). Only in moderate/severe hyper-reactive subjects (excluded borderlines), PD20 was lower in the FEF_25-75≤50% subgroup than in the 1 with FEF_25-75>70%. The hyperreactive subjects percentage, was higher in those with FEF_25-75≤50% and lower in those with FEF_25-75>70% (P<0.0001). FEF_25-75<50% (compared to FEF_25-75>70%) was a higher AHR risk factor, especially in subjects with moderate/severe AHR (OR: 2.18 [IQR:1.41-3.37]; P<0.0001). Thresholds yielding the highest combined sensitivity/specificity for FEF_25-75% were 75.19 (area under curve [AUC]: 0.653) and 74.95 (AUC:0.688) in subjects with PD20<2,400 and <400 µg respectively. FEV1, FVC, and FEV1/FVC measured in subjects with different FEF_25-75≤50%, FEF_25-75>50 and ≤70% or FEF_25-75>70% levels were similar both in normoreactive and hyperreactive subjects.

Conclusions

At asthma onset, reduced baseline FEF_25-75 values with normal FEV1 and FEV1/FVC may predict AHR. Detectable predictive cut-off values do not exist because even normoreactive subjects can show lower FEF_25-75 values. Furthermore, a greater FEF_25-75 reduction may be associated to a more severe AHR, suggesting a possible FEF_25-75 role in the management of asthma when FEV1 and FEV1/FVC are normal.

Airway inflammation and bronchial hyperreactivity in steroid naive children with intermittent and mild persistent asthma

BACKGROUND

Intermittent and mild persistent asthma are defined according to symptom frequency and spirometry and treated differently. To our knowledge, there is no study comparing airway inflammation between intermittent and mild persistent asthmatic children.

MATERIALS AND METHODS

Children aged 7-16 years, referred to our pediatric allergy clinic for recurrent respiratory complaints underwent a detailed clinical history and spirometry with reversibility. None of the subjects had been using regular anti-inflammatory treatment. After a 2-week run-in period during which asthma symptoms were recorded, exhaled NO measurement, bronchial provocation test with adenosine monophosphate and methacholine and sputum induction were performed. Data of patients with intermittent and mild persistent asthma and a control group were compared.

RESULTS

Thirty intermittent, 26 mild persistent asthmatic children, and 21 control subjects were studied. Sputum was obtained from 19 of intermittent asthmatics (63.3%), 18 of mild persistent asthmatics (69.2%), and 13 of control subjects (61.9%). Eosinophil count and exhaled nitric oxide were not different between asthmatic groups. Neutrophil count of children with mild persistent asthma was higher than the intermittent asthmatic group (P = 0.003). Geometric mean of PC20 methacoline values were not different between groups (P = 0.058). Geometric mean of PC20 AMP was lower among patients with mild persistent asthma (P = 0.102).

CONCLUSION

Eosinophilic airway inflammation and direct BHR may not be significantly different in intermittent asthmatic children from their peers with mild persistent disease. Neutrophilic airway inflammation and BHR to an indirect stimuli are more pronounced in the mild persistent group.

Non-asthmatic patients show increased exhaled nitric oxide concentrations

OBJECTIVE

Evaluate whether exhaled nitric oxide may serve as a marker of intraoperative bronchospasm.

INTRODUCTION

Intraoperative bronchospasm remains a challenging event during anesthesia. Previous studies in asthmatic patients suggest that exhaled nitric oxide may represent a noninvasive measure of airway inflammation.

METHODS

A total of 146,358 anesthesia information forms, which were received during the period from 1999 to 2004, were reviewed. Bronchospasm was registered on 863 forms. From those, three groups were identified: 9 non-asthmatic patients (Bronchospasm group), 12 asthmatics (Asthma group) and 10 subjects with no previous airway disease or symptoms (Control group). All subjects were submitted to exhaled nitric oxide measurements (parts/billion), spirometry and the induced sputum test. The data was compared by ANOVA followed by the Tukey test and Kruskal-Wallis followed by Dunn's test.

RESULTS

The normal lung function test results for the Bronchospasm group were different from those of the asthma group (p <0.05). The median percentage of eosinophils in induced sputum was higher for the Asthma [2.46 (0.45-6.83)] compared with either the Bronchospasm [0.55 (0-1.26)] or the Control group [0.0 (0)] (p <0.05); exhaled nitric oxide followed a similar pattern for the Asthma [81.55 (57.6-86.85)], Bronchospasm [46.2 (42.0 -62.6] and Control group [18.7 (16.0-24.7)] (p< 0.05).

CONCLUSIONS

Non-asthmatic patients with intraoperative bronchospasm detected during anesthesia and endotracheal intubation showed increased expired nitric oxide.

Atopic sensitization to common allergens without symptoms or signs of airway disorders does not increase exhaled nitric oxide

BACKGROUND

Elevated fractional exhaled nitric oxide (FENO) associates positively with symptomatic atopy among asthmatics and in the general population. It is, however, unclear whether sensitization to common allergens per se- as verified with positive skin prick tests--affects FENO in healthy individuals.

OBJECTIVE

The aim of this study was to examine the association between FENO and sensitization to common allergens in healthy nonsmoking adults with no signs or symptoms of airway disorders.

METHODS

FENO measurements (flow rate: 50 mL/s), skin prick tests to common inhalant allergens, structured interviews, spirometry, bronchodilatation tests and bronchial histamine challenges were performed on a randomly selected population of 248 subjects. Seventy-three of them (29%) were nonsmoking asymptomatic adults with no history of asthma, persistent or recurrent upper or lower airway symptoms and no signs of airway disorders in the tests listed above.

RESULTS

FENO concentrations were similar in skin prick test positive (n = 32) and negative (n = 41) healthy subjects, with median values of 13.2 and 15.5 ppb, respectively (P = 0.304). No correlation appeared between FENO and the number of positive reactions (r = -0.138; P = 0.244), or the total sum of wheal diameters (r = -0.135; P = 0.254). The nonparametric one-tailed 95% upper limits of FENO among skin prick positive and negative healthy nonsmoking subjects were 29 and 31 ppb, respectively.

CONCLUSIONS

Atopic constitution defined as positive skin prick test results does not increase FENO in healthy nonsmoking adults with no signs or symptoms of airway disorders. This suggests that same reference ranges for FENO can be applied to both skin prick test positive and negative subjects.

The value of exhaled nitric oxide in predicting bronchial hyperresponsiveness in children

Reduced attention span and motor skills in children limit the practicability of bronchial provocation tests. To assess exhaled nitric oxide (FeNO) as a surrogate for bronchial hyperresponsiveness (BHR) in children with possible reactive airway disease, FeNO was measured using the single-breath method in 169 successive outpatients 11 +/- 5 years of age before lung function testing and subsequent bronchial provocation by exercise (n = 165) and methacholine (n = 134). Baseline forced expiratory volume in 1 second (FEV(1)) less than 80% of predicted and/or BHR were seen in 59%. FeNO correlated weakly with PD(20) to methacholine (r = -0.24, p < 0.05), but not with the change in FEV(1) due to exercise-induced bronchoconstriction (EIB) (r = 0.1, p > 0.05). The negative predictive value of FeNO less than 10 ppb for EIB was 94%, but overall accuracy for predicting BHR was low. Measurement of FeNO is not a substitute for bronchial provocation in children.

Effect of inhaled steroid therapy on exhaled nitric oxide and bronchial responsiveness in children with asthma

Inhaled steroid therapy is reported to reduce the level of exhaled nitric oxide (eNO), but the effects of inhaled corticosteroids (ICS) on bronchial hyperresponsiveness (BHR) have been controversial. The aim of this study was to determine the effects of ICS on the relationship between eNO and BHR. Twenty-six children with asthma were recruited, including 14 children who were receiving ICS (ICS group) and 12 who were not (ICS-naive group). The fractional exhaled nitric oxide concentration (FE(NO)) was examined by the recommended online method. To evaluate BHR, an acetylcholine challenge test was performed. In the ICS-naive group, FE(NO) was significantly correlated with PC20 (p < 0.05, r = -0.70), but not in the ICS group. In conclusion, FE(NO) was significantly correlated with BHR in the ICS-naive group, but this relationship was not present in the ICS group. Our results suggest that the use of ICS should be taken into consideration when evaluating the relation between BHR and airway inflammation.

Allergic rhinitis and asthma: inflammation in a one-airway condition

Background

Allergic rhinitis and asthma are conditions of airway inflammation that often coexist.

Discussion

In susceptible individuals, exposure of the nose and lungs to allergen elicits early phase and late phase responses. Contact with antigen by mast cells results in their degranulation, the release of selected mediators, and the subsequent recruitment of other inflammatory cell phenotypes. Additional proinflammatory mediators are released, including histamine, prostaglandins, cysteinyl leukotrienes, proteases, and a variety of cytokines, chemokines, and growth factors. Nasal biopsies in allergic rhinitis demonstrate accumulations of mast cells, eosinophils, and basophils in the epithelium and accumulations of eosinophils in the deeper subepithelium (that is, lamina propria). Examination of bronchial tissue, even in mild asthma, shows lymphocytic inflammation enriched by eosinophils. In severe asthma, the predominant pattern of inflammation changes, with increases in the numbers of neutrophils and, in many, an extension of the changes to involve smaller airways (that is, bronchioli). Structural alterations (that is, remodeling) of bronchi in mild asthma include epithelial fragility and thickening of its reticular basement membrane. With increasing severity of asthma there may be increases in airway smooth muscle mass, vascularity, interstitial collagen, and mucus-secreting glands. Remodeling in the nose is less extensive than that of the lower airways, but the epithelial reticular basement membrane may be slightly but significantly thickened.

Conclusion

Inflammation is a key feature of both allergic rhinitis and asthma. There are therefore potential benefits for application of anti-inflammatory strategies that target both these anatomic sites.

Treating asthma as an inflammatory disease

Asthma is a chronic inflammatory disease involving many different cell types and cellular elements. Evidence suggests that, in the long term, this inflammation leads to remodeling of the airways, airflow obstruction, and the bronchial hyperreactivity symptoms of asthma, and is present even in patients with intermittent disease. Patients with allergic asthma and those with seasonal allergic rhinitis are believed to have minimal persistent inflammation, and the two diseases often occur together. Early intervention with inhaled corticosteroids (ICS) is believed to modify the disease process and may limit long-term remodeling. ICS remain the cornerstone and "gold standard" of treatment for asthma.

Titrating steroids on exhaled nitric oxide in children with asthma: a randomized controlled trial

RATIONALE

Corticosteroids are the antiinflammatory treatment of choice in asthma. Treatment guidelines are mainly symptom-driven but symptoms are not closely related to airway inflammation. The fraction of nitric oxide in exhaled air (FENO) is a marker of airway inflammation in asthma.

OBJECTIVE

We evaluated whether titrating steroids on FENO improved asthma management in children.

METHODS

Eighty-five children with atopic asthma, using inhaled steroids, were allocated to a FENO group (n=39) in which treatment decisions were made on both FENO and symptoms, or to a symptom group (n=46) treated on symptoms only. Children were seen every 3 months over a 1-year period.

MEASUREMENTS

Symptoms were scored during 2 weeks before visits and 4 weeks before the final visit. FeNO was measured at all visits, and airway hyperresponsiveness and FEV1 were measured at the start and end of the study. Primary endpoint was cumulative steroid dose.

RESULTS

Changes in steroid dose from baseline did not differ between groups. In the FENO group, hyperresponsiveness improved more than in the symptom group (2.5 vs. 1.1 doubling dose, p=0.04). FEV1 in the FENO group improved, and the change in FEV1 was not significantly different between groups. The FENO group had 8 severe exacerbations versus 18 in the symptom group. The change in symptom scores did not differ between groups. FENO increased in the symptom group; the change in FENO from baseline differed between groups (p=0.02).

CONCLUSION

In children with asthma, 1 year of steroid titration on FENO did not result in higher steroid doses and did improve airway hyperresponsiveness and inflammation.

Clinical implications of airway inflammation in mild intermittent asthma

OBJECTIVE

To determine whether inhaled corticosteroids should be prescribed to patients with milder forms of asthma and whether markers of airway inflammation should be considered when making therapy decisions.

DATA SOURCES

A PubMed search was performed of the English-language literature published in the preceding 10 years (January 1, 1993, through December 31, 2003) concerning epidemiology, pathophysiology, therapy, and prognosis of mild intermittent asthma, with asthma, mild, and intermittent as indexing terms.

STUDY SELECTION

All relevant studies including author's expert opinions were selected.

RESULTS

Several studies have addressed the question of a possible benefit of maintenance therapy (ie, inhaled steroids) in patients with mild intermittent asthma. Although a diminishing effect on airway inflammation has been widely demonstrated, even in patients with mild disease, the impact of inhaled steroids on the long-term prognosis is much less clear. For patients with mild disease who are long-term inhaled steroid users, alternative therapy strategies, including low-dose inhaled steroids and leukotriene receptor antagonists, have been advocated.

CONCLUSIONS

Mild intermittent asthma is a disease characterized not only by infrequent symptoms and normal lung function but also by chronic airway inflammation, possibly resulting in irreversible airflow limitation if left unattended. Therefore, maintenance therapy, such as (low-dose) inhaled steroids or leukotriene receptor antagonists, should be considered in patients with mild disease. Future studies should give more insight into the impact of prolonged anti-inflammatory therapy on the long-term prognosis of mild intermittent asthma patients. Whether results from these studies will justify a more aggressive treatment for these patients remains to be answered.

Categorizing asthma severity: an overview of national guidelines

Asthma is an inflammatory disease of the airways associated with intermittent episodes of bronchospasm. Corticosteroids are the most effective anti-inflammatory class of medication currently available for the treatment of asthma. However, as higher doses of inhaled corticosteroids are used the risks of systemic exposure and side effects will correspondingly increase. Justification of the benefits from higher doses of inhaled corticosteroids can only be made if patients with more severe asthma can be identified. Methods to categorize asthma severity have been introduced in various national asthma management guidelines. Unfortunately, there are substantial conceptual and practical differences among these recommended approaches to asthma severity categorization. Furthermore, these recommended approaches suffer from a focus on features of asthma control, such as symptoms, short-acting beta-agonist use, and lung function rather than actual measures of asthma severity that would encompass markers of airway inflammation. Without the endpoints necessary to assess airway inflammation, current recommendations for asthma severity categorization may lead to systematic under dosing of appropriate anti-inflammatory therapy with subsequent perpetuation of the asthma exacerbation cycle.

Exhaled nitric oxide in the assessment of asthma

PURPOSE

Asthma is now defined as a TH2-mediated inflammatory disease involving both large and small airways. However, assessment of airways inflammation is limited by techniques that are time consuming and possibly distressing to the patient. Exhaled nitric oxide, an easily and rapidly obtained noninvasive study, is a potential surrogate for measuring airways inflammation, but its clinical utility remains to be determined. This review examines the role of exhaled nitric oxide in assessing and directing therapy of asthmatic airways inflammation.

RECENT FINDINGS

It is well established that exhaled nitric oxide is increased in patients with untreated asthma and decreases with corticosteroid treatment. Exhaled nitric oxide also generally correlates with eosinophilic inflammation in asthmatic patients. Recent studies show that this correlation is especially pronounced in atopic subjects with asthma when compared with nonatopic subgroups. Recent studies also show that exhaled nitric oxide may be useful in identifying subclinical inflammation, assessing the antiinflammatory effects of asthma medications other than inhaled or oral corticosteroids, and heralding an asthma exacerbation. A number of new studies assert the utility of exhaled nitric oxide as a diagnostic tool for asthma.

SUMMARY

Exhaled nitric oxide may be a useful parameter for monitoring asthmatic inflammation, adjusting therapy, and diagnosing asthma, although prospective longitudinal trials investigating the correlation between exhaled nitric oxide and clinical outcomes are necessary to determine its utility.