The relation between adrenal function and the severity of bronchial hyperresponsiveness in children as measured by the methacholine provocation test

Establishment and comparison of combining disease and syndrome model of asthma with "kidney yang deficiency" and "abnormal savda"

THE STUDY WAS THE FIRST TIME TO ESTABLISH AND COMPARE TWO RAT MODELS OF TWO COMMON SYNDROMES: Kidney Yang Deficiency syndrome (KYDS) in traditional Chinese medicine (TCM) and abnormal savda syndrome (ASS) in traditional Uighur medicine (TUM). Then, we also established and evaluated rat models of combining disease and syndrome models of asthma with KYDS or ASS. Results showed that usage of the high dose of corticosterone (CORT) injection or external factors could successfully establish the KYDS or ASS rat models, and the two models had similar changes in biological characterization, abnormal behaviors, dysfunction of hypothalamic-pituitary-target organ axes (HPTOA), and sympathetic/parasympathetic (S/P) nerve system but varied in different degrees. The rat models of combining disease and syndrome of asthma with KYDS or ASS had either pathological characteristics of asthma such as airway hyperresponsiveness (AHR), airway inflammation, airway remodeling, which were more serious than allergy exposure alone, or the syndrome performance of Kidney Yang Deficiency in TCM and abnormal savda in TUM. These findings provide a biological rationale for further investigation of combining disease and syndrome model of asthma as an effective animal model for exploring asthma based on the theory of traditional medicine.

Hypothalamic-pituitary-adrenal axis suppression in asthmatic school children

BACKGROUND AND OBJECTIVE

Hypothalamic-pituitary-adrenal axis suppression (HPAS) when treating children with corticosteroids is thought to be rare. Our objective was to determine the prevalence of and predictive factors for various degrees of HPAS.

METHODS

Clinical features of HPAS, doses, adherence, asthma score, and lung functions were recorded in 143 asthmatic children. The overnight metyrapone test was performed if morning cortisol was >83 nmol/L. Spearman correlations coefficients (r) were calculated between 3 postmetyrapone outcomes and each continuous variable. A multiple linear regression model of √postmetyrapone adrenocorticotropic hormone (ACTH) and a logistic regression model for HPAS were developed.

RESULTS

Hypocortisolemia was seen in 6.1% (1.8-10.5), hypothalamic-pituitary suppression (HPS) in 22.2% (14.5-29.9), adrenal suppression in 32.3% (23.7-40.9), HPAS in 16.3% (9.3-23.3), and any hypothalamic-pituitary-adrenal axis dysfunction in 65.1% (56.5-72.9). Log daily nasal steroid (NS) dose/m(2) was associated with HPAS in the logistic regression model (odds ratio = 3.7 [95% confidence interval: 1.1-13.6]). Daily inhaled corticosteroids (ICSs) + NS dose/m(2) predicted HPAS in the univariate logistic regression model (P = .038). Forced expiratory volume in 1 second/forced vital capacity <80% was associated with HPAS (odds ratio = 4.1 [95% confidence interval: 1.0-14.8]). Daily ICS + NS/m(2) dose was correlated with the postmetyrapone ACTH (r = -0.29, P < .001). BMI (P = .048) and percent adherence to ICS (P < .001) and NS (P = .002) were predictive of √postmetyrapone ACTH (R(2) = .176).

CONCLUSIONS

Two-thirds of children on corticosteroids may have hypothalamic-pituitary-adrenal axis dysfunction. In one-third, central function had recovered but adrenal suppression persisted. Predictive factors for HPAS are NS use, BMI, and adherence to ICS and NS.

Change of bronchial hyperresponsiveness in asthmatic children

INTRODUCTION

Bronchial hyperresponsiveness (BHR) is a factor in predicting bronchial asthma independently of inflammation markers.

OBJECTIVE

The aims were to determine the frequency and important predictive facts of BHR and the effect of prophylaxis by Global Initiative for Asthma (GINA) and National Asthma Education and Prevention Program (NAEPP) on BHR in asthmatic children.

METHODS

BHR in 106 children was evaluated by the bronchoprovocation test with methacholine.

RESULTS

The prevalence rate of symptomatic BHR is 18% for crucial point of PC20 = 4.1 +/- 3.03 mg/ml and PD20 = 3.22 +/- 2.59 micromol methacholine. On average asthmatic children express moderate BHR, which persists even two years after administering prophylaxis. After two years bronchial reactivity is significantly smaller, the change of FEV1 is significantly smaller, the velocity of change of slope dose response curve (sDRC) is faster and the provocative concentration of methacholine that causes wheezing is 2-3 times lower. A mild sDRC shows milder bronchoconstriction after two years. The fast change of bronchial reactivity in 41% of asthmatic children is contributed to aero-pollution with sulfur dioxide and/or, possible insufficient and/or inadequate treatment during two years of administering prophylaxis. A simultaneous effect of allergens from home environment and grass and tree pollens and of excessive aero-pollution on children's airways is important in the onset of symptomatic BHR. After two years of treatment by GINA and NAEPP children do not show asthma symptoms or show mild asthma symptoms, however bronchial sensitivity remains unchanged.

CONCLUSION

Optimal duration of anti-inflammatory treatment in asthmatic children who show moderate bronchial hyperresponsiveness should be longer than two years.

Hypothalamic-pituitary-adrenal axis suppression in asthmatic children on inhaled and nasal corticosteroids: is the early-morning serum adrenocorticotropic hormone (ACTH) a useful screening test?

BACKGROUND

Hypothalamic-pituitary-adrenal axis suppression (HPAS) in asthmatic children treated with inhaled corticosteroids (ICS), with or without nasal steroids (NS), may be more common than previously thought. Only dynamic testing will identify children at risk of adrenal crisis. It is impractical to test all asthmatic children for HPAS with a gold standard adrenal function test, i.e. the metyrapone or insulin tolerance test.

OBJECTIVE

To determine which clinical or biochemical parameter is the most useful screening test for HPAS in asthmatic children.

METHODS

Twenty-six asthmatic children, 5-18 yr old, on ICS ± NS, not treated with oral or topical steroids in the preceding year were recruited. Height, weight, height velocity, weight velocity and a change in systolic blood pressure from the recumbent to the standing position (ΔSBP) were recorded. Early-morning urine for urinary free cortisol (UFC) and urinary cortisol metabolites (UCM) was collected. UFC was analysed by both a chemiluminescent assay and gas chromatography/mass spectrometry (GC-MS). Morning serum cortisol and adrenocorticotropic hormone (ACTH) levels were measured. The overnight metyrapone test was performed if the fasting morning serum cortisol was >83 nmol/l. HPAS was diagnosed if the ACTH failed to rise >100 pg/ml after metyrapone. Spearman correlation coefficients (r) were calculated between the post-metyrapone ACTH and each variable. A receiver-operating characteristics (ROC) curve was drawn for the most promising test, and the diagnostic performance was calculated.

RESULTS

All clinical and biochemical parameters investigated were weakly and non-significantly correlated with the post-metyrapone ACTH, except for the morning serum ACTH (r = 0.68; p <0.001). The best discrimination between those who have and those who do not have HPAS is a morning serum ACTH level of 11.7 pg/ml. This corresponds to a sensitivity of 0.89 (0.57-0.98), a specificity of 0.77 (0.53-0.90), a positive predictive value of 0.67 (0.39-0.87), a negative predictive value of 0.93 (0.69-0.99), an accuracy of 0.81 (0.61-0.94), a positive likelihood ratio of 3.78 (1.68-9.49) and a negative likelihood ratio of 0.15 (0.03-0.60).

CONCLUSIONS

The morning serum ACTH level was found to be the most useful screening test to detect HPAS in this sample of children receiving ICS ± NS. A larger study should be undertaken to refine the diagnostic precision of the morning serum ACTH level.

Dysregulation of the stress response in asthmatic children

The stress system co-ordinates the adaptive responses of the organism to stressors of any kind. Inappropriate responsiveness may account for increased susceptibility to a variety of disorders, including asthma. Accumulated evidence from animal models suggests that exogenously applied stress enhances airway reactivity and increases allergen-induced airway inflammation. This is in agreement with the clinical observation that stressful life events increase the risk of a new asthma attack. Activation of the hypothalamic-pituitary-adrenal (HPA) axis by specific cytokines increases the release of cortisol, which in turn feeds back and suppresses the immune reaction. Data from animal models suggest that inability to increase glucocorticoid production in response to stress is associated with increased airway inflammation with mechanical dysfunction of the lungs. Recently, a growing body of evidence shows that asthmatic subjects who are not treated with inhaled corticosteroids (ICS) are likely to have an attenuated activity and/or responsiveness of their HPA axis. In line with this concept, most asthmatic children demonstrate improved HPA axis responsiveness on conventional doses of ICS, as their airway inflammation subsides. Few patients may experience further deterioration of adrenal function, a phenomenon which may be genetically determined.

The hypothalamic-pituitary-adrenal axis in asthmatic children

Reduced responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in patients with various chronic allergic inflammatory disorders and a blunted HPA axis response of poorly controlled asthmatics before long-term treatment with inhaled corticosteroids (ICS) have been reported. It seems that pro- and anti-inflammatory cytokines might be involved in the attenuation of cortisol and adrenocorticotropic hormone (ACTH) responses to stress in these patients. Although long-term ICS treatment might produce mild adrenal suppression in some asthmatic children, improvement of adrenal function has been detected in the majority of cases. We postulate that the anti-inflammatory effects of ICS result both in asthma remission and HPA axis improvement. Adrenal suppression of some asthmatic patients on maintenance ICS seems to be a separate phenomenon, possibly constitutionally or genetically determined.