Plasma endothelin-1 immunoreactivity in asthmatic children

Comorbidity of Neurally Mediated Syncope and Allergic Disease in Children

Neurally mediated syncope (NMS) is the most common underlying disease of pediatric syncope, which generally includes vasovagal syncope (VVS), postural tachycardia syndrome (POTS), and situational syncope. Allergic diseases involving the respiratory system, digestive system, skin, and other systems are prevalent in children. In recent years, increasing attention has been paid to children with the comorbidity of NMS and allergic diseases. This article reviews the featured clinical manifestations and pathogenesis of the comorbidity according to the progress of related studies. Clinical studies have shown that the comorbidity rate of pediatric VVS and/or POTS with allergic diseases amounts to ~30-40%, referring to the whole population of children with VVS and/or POTS. Additionally, children with the comorbidity present some relatively special clinical characteristics. A series of mechanisms or regulatory factors relating to allergies, such as the imbalance of vasoactive elements, dysfunction of the autonomic nervous system (ANS), and autoimmunity may play a role in the development of the comorbidity. Moreover, 90% of children with cough syncope, a type of situational syncope, have a history of asthma, indicating a potential relationship between asthma and NMS. Further studies exploring the clinical characteristics and pathogenesis of the comorbidity are still needed to aid in the diagnosis and treatment of children with NMS.

The effect of the endothelin-1 receptor antagonist, bosentan, on patients with poorly controlled asthma: a 17-week, double-blind, placebo-controlled crossover pilot study

OBJECTIVE

To determine the effect of bosentan on subjects with poorly controlled asthma.

METHODS

This was a double-blind, placebo-controlled crossover pilot study. Subjects were poorly controlled on anti-inflammatory and long acting β-agonist therapy, and had a baseline forced expiratory volume in 1 second (FEV1) percent of predicted of 40 -70%. Subjects were randomized to receive either bosentan or placebo at the therapeutic dose of 125 mg twice a day for 4 weeks, and then crossed over to the alternate therapy. The asthma control test, asthma symptom scores, rescue albuterol use, and FEV1 were measured at baseline and during the last week of bosentan and placebo. Acute changes in FEV1 were measured after the initial therapeutic bosentan and placebo dose.

RESULTS

Seven of eleven randomized subjects completed the protocol. There was no difference in change in FEV1 after the bosentan phase when compared with placebo (+0.08 ± 0.31 L and +0.23 ± 0.26 L p = .34). Changes from baseline values in the asthma control test and asthma symptom scores were also similar in bosentan and placebo phases (+1.71 ± 3.99 and +4.57 ± 4.39 p = .16) and (+0.14 ± 9.3 and -0.29 ± 5.28 p = .93). Rescue β-agonist use did not change significantly during the last week of the bosentan phase when compared with placebo phase (-5.86 ± 0.94 puffs and -5.14 ± 16.85 puffs p = .94). Additionally, there was no difference in the change in FEV1 4 hours after bosentan 125 mg and placebo (-0.08 L ± 0.07 vs. +0.04 L ± 0.20 p = .20).

CONCLUSIONS

In this pilot study, 4 weeks of bosentan did not improve FEV1, β-agonist use, asthma symptom score, or asthma control test score in patients with poorly controlled asthma when compared with placebo.

Vascular endothelial growth factor overexpression in induced sputum of children with bronchial asthma

Vascular endothelial growth factor (VEGF) induces angiogenesis and increases vascular permeability participating in narrowing of the airway lumen that follows lung injury. We sought to investigate the expression of VEGF in induced sputum during and after recovery from acute episodes of bronchial asthma in children. Eighteen asthmatic children with acute attacks of varying severity were subjected to VEGF estimation by an enzymatic immunoassay in induced sputum. They were followed up till complete remission of symptoms and signs and were then retested. VEGF was also estimated in sputum induced from age 34 and sex-matched healthy children enrolled as a control group. The sputum VEGF levels during acute asthma [median = 71 ng/ml; mean (s.d.) = 114.6 (121.8) ng/ml] were significantly higher than the levels estimated during remission [median = 50 ng/ml; mean (s.d.) = 45.7 (24.2) ng/ml] and both were higher than the corresponding levels of the control group [median = 36 ng/ml; mean (s.d.) = 31.3 (17.2) ng/ml]. VEGF levels during asthmatic episodes correlated positively to the recovery levels (r = 0.6, p = 0.009). The patients' VEGF expression did not vary with asthma severity, serum total IgE concentration, peripheral blood eosinophil count, or erythrocyte sedimentation rate of patients. Children on corticosteroids inhalation therapy at enrollment had sputum VEGF levels that were comparable to those on other therapies. The increased expression of sputum VEGF in asthmatic children reinforces the concept that it might have a pathogenetic role in bronchial asthma and may represent a biomarker of airway inflammation.

NFATc3 mediates chronic hypoxia-induced pulmonary arterial remodeling with alpha-actin up-regulation

Physiological responses to chronic hypoxia include polycythemia, pulmonary arterial remodeling, and vasoconstriction. Chronic hypoxia causes pulmonary arterial hypertension leading to right ventricular hypertrophy and heart failure. During pulmonary hypertension, pulmonary arteries exhibit increased expression of smooth muscle-alpha-actin and -myosin heavy chain. NFATc3 (nuclear factor of activated T cells isoform c3), which is aCa(2+)-dependent transcription factor, has been recently linked to smooth muscle phenotypic maintenance through the regulation of the expression of alpha-actin. The aim of this study was to determine if: (a) NFATc3 is expressed in murine pulmonary arteries, (b) hypoxia induces NFAT activation, (c) NFATc3 mediates the up-regulation of alpha-actin during chronic hypoxia, and (d) NFATc3 is involved in chronic hypoxia-induced pulmonary vascular remodeling. NFATc3 transcript and protein were found in pulmonary arteries. NFAT-luciferase reporter mice were exposed to normoxia (630 torr) or hypoxia (380 torr) for 2, 7, or 21 days. Exposure to hypoxia elicited a significant increase in luciferase activity and pulmonary arterial smooth muscle nuclear NFATc3 localization, demonstrating NFAT activation. Hypoxia induced up-regulation of alpha-actin and was prevented by the calcineurin/NFAT inhibitor, cyclosporin A (25 mg/kg/day s.c.). In addition, NFATc3 knock-out mice did not showed increased alpha-actin levels and arterial wall thickness after hypoxia. These results strongly suggest that NFATc3 plays a role in the chronic hypoxia-induced vascular changes that underlie pulmonary hypertension.

Montelukast decreases plasma endothelin-1 and serum eosinophil cationic protein levels in paediatric atopic asthma

BACKGROUND AND OBJECTIVE

Endothelin-1 (ET-1) is produced by vascular endothelial cells and epithelial cells, T-lymphocytes and phagocytes. Increased ET-1 levels have been demonstrated in the bronchial epithelium of asthma patients. In vitro, ET-1 stimulates mucus secretion, activates proinflammatory cells - macrophages and mast cells - and serves as a mitogenic stimulus for fibroblasts and smooth muscle. In addition, ET-1 activates phospholipase 2. Compared with healthy individuals, asthma patients have increased ET-1 levels during an attack and following stabilisation. Our study was designed to examine plasma ET-1 (P-ET) levels in paediatric atopic patients newly diagnosed with persistent mild bronchial asthma and 1 month after initiation of montelukast therapy.

METHODS

Patients' histories were examined, and their blood eosinophil leucocyte count and levels of total serum immunoglobulin E (S-IgE), serum eosinophil cationic protein (S-ECP) and P-ET were determined. Thirty-six patients with persistent mild bronchial asthma were treated with the leukotriene receptor antagonist montelukast, administered once a day for 4 weeks. Second P-ET and S-ECP level determinations were made 4 weeks later with all the children included in the study. P-ET levels were also determined in a group of 27 healthy children who had no atopy in their medical histories and were taking no drugs (including montelukast), and who served as controls.

RESULTS

The mean +/- SD pretreatment P-ET level in the 36 study children was 11.542 +/- 6.408 pg/L, and this decreased to 5.636 +/- 4.419 pg/L after 1 month's therapy with montelukast (statistically significant difference; p < 0.0001). Both of these values were significantly higher (p < 0.0001 and p < 0.031, respectively) than the mean level in the control group of 27 children (3.543 +/- 2.497 pg/L). The mean pretreatment S-ECP level was 35.78 +/- 19.58 microg/L, and this decreased to 19.54 +/- 13.86 microg/L after 1 month's therapy (p < 0.001).

CONCLUSIONS

This study demonstrated a decrease in P-ET levels in children with mild asthma receiving montelukast. This indicates a reduction in the severity of the inflammatory response and, hence, provides evidence for the anti-inflammatory effect of montelukast. Monitoring both ET-1 and ECP levels at regular follow-up may be useful in assessing these two facets of activity of chronic inflammation in bronchial asthma.