Exhaled nitric oxide as a simple assessment of airway hyperresponsiveness in bronchial asthma and chronic cough patients

The diagnostic value of bronchial provocation testing combined with fractional exhaled nitric oxide (FeNO) in children with chest tightness-variant asthma (CTVA)

BACKGROUND

Chest tightness-variant asthma (CTVA) is a novel atypical asthma characterized by chest tightness as the sole or primary symptom.

OBJECTIVES

To investigate the value of bronchial provocation testing combined with fractional exhaled nitric oxide (FeNO) in the diagnosis of CTVA in children.

METHODS

This study included 95 children aged 6-14 years with chest tightness as the sole symptom, with a duration of symptoms exceeding 4 weeks. All subjects underwent FeNO measurement, pulmonary function testing, and bronchial provocation testing using the Astograph method. Subjects with positive bronchial provocation testing were classified as the CTVA group, while those with negative results served as the non-CTVA control group.

RESULTS

The lung function of children in both groups was normal. The FeNO level in the CTVA group was (22.35 ± 9.91) ppb, significantly higher than the control group (14.85 ± 5.63) ppb, with a statistically significant difference (P < 0.05). The value of FeNO in diagnosing CTVA was analyzed using an ROC curve, with an area under the curve of 0.073 (P < 0.05). The optimal cutoff point for diagnosing CTVA using FeNO was determined to be 18.5 ppb, with a sensitivity of 60.3 % and specificity of 77.8 %. There was a negative correlation between FeNO and Dmin as well as PD15 (P = 0.006).

CONCLUSION

FeNO can serve as an adjunctive diagnostic tool for CTVA, with the optimal cutoff point for diagnosing CTVA being 18.5 ppb. However, FeNO is not a specific diagnostic marker for CTVA and should be used in conjunction with bronchial provocation testing to enhance its diagnostic value.

The CC16 A38G polymorphism is associated with asymptomatic airway hyper-responsiveness and development of late-onset asthma

BACKGROUND

Clara cell secretory protein (CC16) is expressed primarily in the respiratory tract and is a potent anti-inflammatory agent that protects the airway from inflammation. The associations of the A38G polymorphism in this gene with asymptomatic airway hyper-responsiveness (AHR), which is considered a risk factor for future asthma in adults, and the development of adult-onset asthma are unclear.

OBJECTIVE

To evaluate the association of the CC16 A38G polymorphism with asymptomatic AHR in healthy young adults and the development of adult-onset asthma and the association between plasma CC16 level according to this genotype and asymptomatic AHR.

METHODS

Nonspecific AHR was measured in 154 asymptomatic, young, healthy adults using a continuous methacholine inhalation method. The cumulative dose values of inhaled methacholine measured at the inflection point at which respiratory conductance started to decrease (Dmin) were used as an index of AHR. Case-control analysis was performed for the association between this polymorphism and the development of asthma in 1,086 unrelated Japanese subjects (504 subjects with asthma and 582 healthy subjects).

RESULTS

The 38AA + AG genotype was associated with lower Dmin values and lower plasma CC16 levels (P = .012 and .020). There was a significant positive correlation between Dmin values and plasma CC16 levels (P = .012). In the case-control study, the 38AA + AG genotype was significantly associated with late-onset asthma (onset at >40 years; odds ratio, 1.63; P = .016).

CONCLUSION

These results suggest that the CC16 A38G polymorphism may play a role in asymptomatic AHR and contribute to the development of late-onset asthma.

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.

Relationship between exhaled nitric oxide measured by two offline methods and bronchial hyperresponsiveness in Japanese adults with asthma

BACKGROUND

Exhaled nitric oxide (eNO) is a useful marker of eosinophilic airway inflammation in asthmatics. There have been no studies to show the relationship between eNO measured by offline methods and the degree of bronchial hyperresponsiveness in asthmatic patients treated with inhaled corticosteroids.

METHODS

The study population comprised asthmatics at our outpatient clinic. We measured eNO levels by two methods ("eNOs" was measured with a Sievers kit; and "eNOc" was measured with a kit from the Center for Environmental Information Science, Japan). We also used spirometry to test bronchial hyperresponsiveness to acetylcholine (PC(20Ach)).

RESULTS

We recruited 192 stable asthmatics. There was a significant relationship between eNOs and eNOc (r = 0.919, p < 0.001). LogPC(20Ach) levels were negatively correlated with eNOs or eNOc levels (eNOs, r = -0.31, p < 0.001; eNOc, r = -0.23, p = 0.0013). We classified the subjects into two groups based on eNOs levels ((A) the subjects with high eNOs levels (n = 92) and (B) the subjects with normal eNOs levels (n = 100)) ; logPC(20Ach) was significantly correlated with eNOs (r = -0.34, p = 0.001) or eNOc (r = -0.28, p = 0.0075) but not correlated with %FEV(1) in (A), whereas logPC(20Ach) was not significantly correlated with eNO but significantly correlated with %FEV(1) (r = 0.33, p = 0.002) in (B).

CONCLUSIONS

Levels of eNOs and eNOc were correlated with the degree of bronchial hyperresponsiveness to acetylcholine in adult asthmatics treated with inhaled corticosteroids. Our findings suggest that offline monitoring of eNO will facilitate the management of bronchial asthma in patients treated with these drugs.

Serum concentration of C-reactive protein is not a good marker of bronchial hyperresponsiveness

Introduction:

Asthmatic inflammation is responsible for vital features of the disease, including bronchial hyperresponsiveness (BHR). At present we do not have precise markers for monitoring asthmatic inflammation. C-reactive protein (CRP), a marker of systemic inflammation, seemed to be a factor which could also reflect the level of asthmatic inflammation expressed by BHR. Therefore the relationship between CRP concentration and BHR was evaluated.

Materials and Methods:

One hundred and two patients entered the study. A skin prick test with a broad spectrum of common aeroallergens as well as baseline spirometry and a histamine bronchoprovocation test were performed in each subject. Blood samples for high-sensitivity CRP (hsCRP) measurement were taken before the bronchial challenge tests.

Results:

Serum hsCRP concentrations ranged from 0.20 to 14.5 mg/l (median: 1.2 mg/l, 25–75% quartiles: 0.6–2.4). Positive skin prick tests were found in 26 subjects. Bronchial hyperresponsiveness was confirmed in 42 patients (first subgroup), while 60 subjects did not demonstrate BHR (second subgroup). Among the patients with BHR, asthma was diagnosed in 33 cases and Corrao syndrome in 9. In both subgroups, serum hsCRP concentrations had similar levels (median: 1.4 mg/l, 25–75% quartiles: 0.8–2.4 and median: 0.9 mg/l, 25–75% quartiles: 0.5–2.8, respectively; p=0.297). There was no statistically significant correlation (r= −0.163, p=0.302) between serum hsCRP concentration and the level of BHR expressed as the 20% provocative concentration for histamine. In addition, hsCRP serum concentration, after adjustment for age, atopy, body mass index, and gender, was not a significant predictor of positive histamine bronchoprovocation test results (p=0.22, OR=0.86, 95% CI).

Conclusions:

Serum hsCRP concentration is not a good marker of BHR, which is mainly dependent on asthmatic inflammation and is measured during bronchial challenge with histamine. This finding is important for interpreting and discussing results obtained from epidemiological and population-based studies on relationships between either CRP concentration and BHR or local and systemic inflammation.

[Exhaled nitric oxide in the diagnosis and monitoring of lung diseases]

In recent 10 years there has been an explosion of interest in the analysis of breath constituents as a way of monitoring airway inflammation in lung diseases. Monitoring of inflammation may assist in differential diagnosis of lung diseases, assessment of their severity and response to appropriate treatment. Among these novel non-invasive methods, exhaled nitric oxide has been the most extensively studied. Its measurement has recently been standardized, and there are now commercially available nitric oxide analyzers. Concentration of exhaled nitric oxide is markedly elevated in asthma, and its elevation is positively related to the degree of eosinophilic airway inflammation, airway hyperresponsiveness and symptoms. Furthermore, evidence suggests that exhaled nitric oxide-driven asthma treatment provides more precise asthma control compared to conventional treatment protocols. With regard to other lung diseases, in chronic obstructive pulmonary disease exhaled nitric oxide may be useful in predicting steroid responsiveness, while in lung transplant recipients its measurement could contribute to the detection of asymptomatic infections and rejection processes.

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.

History of serious asthma exacerbations should be included in guidelines of asthma severity

BACKGROUND

It is unclear whether asthma severity measured with consensus guidelines is better than a history of a serious asthma exacerbation in predicting current disease activity and future clinical course.

OBJECTIVES

We sought to (1) compare asthma severity determined by using the Global Initiative for Asthma guidelines with a history of a serious asthma exacerbation as predictors of pulmonary function, bronchial hyperreactivity, and disease activity and (2) determine whether exacerbation history significantly adds to asthma severity in its ability to predict the same variables.

METHODS

Forty-eight adolescents with a history of a serious asthma exacerbation were compared with 69 adolescents with asthma but without such a history. Groups were matched for age, sex, and ethnicity (age, 14.59 +/- 1.74 years; 56% male; 58% white).

RESULTS

Forty-two percent of subjects had severe, 28% had moderate, 15% had mild persistent, and 15% had mild intermittent asthma. Asthma severity and exacerbation history were associated with pulmonary function and markers of disease activity, whereas only exacerbation history predicted bronchial hyperreactivity (P <or= .001). Including exacerbation history significantly augmented the ability of the severity categories to predict the asthma measures.

CONCLUSION

Although asthma severity and a history of a serious asthma exacerbation both predict pulmonary function abnormalities and current disease activity, bronchial hyperreactivity was only associated with exacerbation history. Exacerbation history improves the ability of severity to predict these key asthma measures.

CLINICAL IMPLICATIONS

Adding a history of a serious asthma exacerbation to the consensus guidelines for asthma severity is likely to improve the ability of these clinical tools to predict current disease activity and future clinical course.

Association between nonspecific airway hyperresponsiveness and Arg16Gly beta2-adrenergic receptor gene polymorphism in asymptomatic healthy Japanese subjects

BACKGROUND

Nonspecific airway hyperresponsiveness (AHR), a cardinal feature of asthma, is thought to result from several genetic and environmental factors. Asymptomatic AHR in nonasthmatic healthy subjects might be a risk factor for the development of asthma. Genetic variations in codons 16 and 27 of the human beta(2)-adrenergic receptor (beta(2)-AR) alter receptor function in vitro and are associated with various asthma-related phenotypes, including asthma severity and AHR. To date, however, few reports have examined the impact of beta(2)-AR gene polymorphism on AHR in asymptomatic healthy subjects.

OBJECTIVE

To determine whether polymorphism of the beta(2)-AR gene (Arg16Gly and Gln27Glu) might influence nonspecific AHR in asymptomatic healthy Japanese subjects.

DESIGN AND PARTICIPANTS

A cohort of 120 asymptomatic healthy subjects was analyzed using a stepwise linear regression model. Nonspecific airway responsiveness was measured using a continuous methacholine inhalation method (Astograph; Chest; Tokyo, Japan). We used values of the cumulative dose of inhaled methacholine measured at the inflection point at which respiratory conductance starts to decrease (Dmin) as an index of AHR. Genotyping to identify polymorphisms at codons 16 and 27 was conducted using an assay combining kinetic real-time quantitative polymerase chain reaction with allele-specific amplification.

RESULTS

The Gly16Gly genotype was associated with lower Dmin values. The log Dmin value of asymptomatic healthy subjects carrying the Arg16 allele (Arg16/Arg or Arg16/Gly, n = 90) was 1.09 +/- 0.56 (mean +/- SD), while those homozygous for the Gly16 allele (n = 30) yielded a log Dmin value of 0.85 +/- 0.56 (p < 0.05).

CONCLUSION

This study indicates that a specific beta(2)-AR polymorphism at codon 16 might be a genetic determinant of AHR, as judged by methacholine-induced bronchoconstriction in asymptomatic healthy subjects.

Airway inflammation in subjects with gastro-oesophageal reflux and gastro-oesophageal reflux-related asthma

STUDY OBJECTIVES

Asthma and gastro-oesophageal reflux (GER) are both characterized by airway inflammation.

DESIGN

The purposes of this work were (i) to study airway inflammation in patients troubled by gastro-oesophageal reflux (GER) and GER associated with asthma, (ii) to ascertain whether GER can aggravate asthma by exacerbating the pre-existing airway inflammation and oxidative stress and (iii) to establish the validity of analysing breath condensate and induced sputum when studying the airways of subjects affected by GER. PATIENT S AND METHODS: We enrolled 14 patients affected by mild asthma associated with GER (40 +/-12 years), nine with mild but persistent asthma (39 +/- 13 years), eight with GER (35 +/- 11 years) and 17 healthy subjects (37 +/- 9 years). Sputum cell counts and concentrations of interleukin-4 (IL-4), IL-6 and 8-isoprostane were measured in breath condensate and supernatant.

MEASUREMENTS AND RESULTS

GER-related asthma is characterized by an eosinophilic inflammation, as determined by elevated concentrations of IL-4 in breath condensate and sputum supernatant, and by sputum cell analysis. GER alone presents a neutrophilic pattern of inflammation when determined by elevated concentrations of IL-6 in sputum cell analysis. A concomitant increase has been found in 8-isoprostane in GER associated (or not associated) with asthma.

CONCLUSIONS

We conclude that GER is characterized by a neutrophilic airway inflammation and by increased oxidative stress. GER does not however aggravate pre-existing airway inflammation in asthma patients. Determinations of inflammatory and oxidant markers in the breath condensate of subjects with GER reflect these measured in the induced sputum.

Exhaled markers in the monitoring of airways inflammation and its response to steroid's treatment in mild persistent asthma

The measure of inflammatory cytokines in the exhaled breath condensate has been recently proposed for use in monitoring asthma and the therapeutic response to steroids. The aim of the present study was to investigate the usefulness of measuring exhaled IL-6, IL-4 and pH in mild persistent asthma. Furthermore the effects on these markers of inhaled steroids were assessed. The study enrolled 28 asthmatic (15 males, 38+/-12 years) and 15 healthy subjects (5 males, 35+/-6 years). IL-6, IL-4 and pH were measured in the exhaled breath condensate of the subjects studied. Significantly higher concentrations of IL-6 and IL-4 were observed in the breath condensate of asthmatic patients (7.1+/-1.1 and 64.4+/-8.3 pg/ml) compared to controls (2.7+/-0.6 and 31.7+/-3.5 pg/ml), p<0.001. Furthermore, exhaled IL-4 fell significantly after treatment with inhaled steroids for 6 months (47.9+/-3.2 pg/ml, p<0.001) while exhaled IL-6 did not (6.4+/-1.0 pg/ml, p=0.8). The exhaled pH turned out to be lower in asthmatic subjects than in controls (7.39+/-0.11 vs. 7.85+/-0.14; P<0.001) but trended towards control levels after steroid treatment (7.65+/-0.16, P<0.001). We conclude that the measurement of exhaled IL-4 and pH in mild asthmatic subjects could be a useful way of monitoring their airway inflammation as well as their response to the treatment.