Exhaled nitric oxide decreases during exercise-induced bronchoconstriction in children with asthma

Nitric oxide (NO) produced in the airways can be either detrimental or protective to the host. To investigate the role of NO in the pathogenesis of exercise-induced bronchoconstriction (EIB), we measured exhaled NO (ENO) after exercise challenge in 39 asthmatic and six normal children. FEV(1) and ENO were measured before and at 0, 5, 10, and 15 min after exercise performed on a treadmill for 6 min. EIB was defined as a decrease in FEV(1) of more than 15% after the exercise. Normal children (control group) did not have EIB. Twenty-one patients with asthma had EIB (EIB group) whereas the remaining 18 patients did not (non-EIB group). The baseline ENO value was significantly higher in the asthmatic children than in the normal children, and there was a positive correlation between the maximal percent decrease in FEV(1) and the baseline ENO value (r = 0.501, p = 0.012). At the end of the exercise, ENO had decreased in all the subjects. In the non-EIB and control groups, ENO rebounded to above the baseline at 5 min after the exercise and thereafter. In contrast, ENO remained at a decreased level in the EIB group. The change in ENO did not correlate with the change in minute ventilation, and beta-agonist inhalation at the peak of EIB that accelerated the recovery of FEV(1) did not affect the depressed level of ENO, demonstrating that the reduction of ENO is not a simple consequence of increased ventilation nor airway obstruction. Among the EIB group, steroid-treated patients showed sooner recovery in ENO after the exercise than steroid-naive patients. Our study suggests that NO production in response to exercise may be impaired in patients with EIB, and that ENO represents not only airway inflammation but also a protective function of NO in EIB.

Chemokines induce eosinophil degranulation through CCR-3

BACKGROUND

Such CC chemokines as eotaxin and RANTES induce preferential eosinophil recruitment in allergic inflammation. They also elicit proinflammatory effector functions of eosinophils, such as enhanced adhesion and superoxide generation. Eosinophil degranulation by chemokines, however, has not been studied in detail.

OBJECTIVE

The purpose of this study was to identify chemokines and their corresponding receptors that induce eosinophil degranulation by using a panel of chemokines and blocking antibodies to candidate receptors.

METHODS

Highly purified eosinophils were preloaded with Fura-2 and stimulated with a panel of chemokine ligands for 14 known chemokine receptors: CCR1 to CCR8, CXCR1 to CXCR4, CX3CR1, and XCR1. Calcium influx was measured with fluorescence spectrometry. Eosinophils were also stimulated with the chemokines in the presence or absence of IL-5, and levels of eosinophil-derived neurotoxin were measured in the supernatant with RIA. Specific antibodies to chemokine receptors were used to block degranulation.

RESULTS

Calcium influx was induced by monocyte chemotactic protein (MCP) 1, MCP-3, MCP-4, RANTES, eotaxin, IL-8, and stromal cell-derived factor 1alpha, which are chemokines that bind several chemokine receptors. However, degranulation was induced only by CCR3 ligands, including MCP-3, MCP-4, RANTES, and eotaxin. Priming of eosinophils with IL-5 enhanced CCR3 ligand-induced degranulation but did not cause non-CCR3 ligands to induce eosinophil-derived neurotoxin release. An antibody against CCR3 significantly inhibited degranulation induced by CCR3 ligands, eotaxin, or RANTES.

CONCLUSION

These results suggest that chemokine-induced eosinophil degranulation, a major effector of eosinophil functions, is mediated through only CCR3, although some non-CCR3 ligands induce calcium influx in eosinophils. CCR3 may be an important target in the treatment of eosinophilic inflammation.

Chemokine production by the BEAS-2B human bronchial epithelial cells: differential regulation of eotaxin, IL-8, and RANTES by TH2- and TH1-derived cytokines

BACKGROUND

Bronchial epithelial cells produce many types of chemokines and may contribute to lung inflammation by recruiting inflammatory cells. The CC chemokine eotaxin is a potent, eosinophil-specific chemoattractant that has been detected in the bronchial epithelium of patients with asthma.

OBJECTIVES

The aim of this study was to investigate the regulatory mechanisms of chemokine production from bronchial epithelium by inflammatory cytokines, especially T(H)2- and T(H)1-derived cytokines, in bronchial asthma.

METHODS

BEAS-2B human bronchial epithelial cells were cultured with TNF-alpha, IL-4, IL-13, and IFN-gamma alone or in combination, after which supernatants were assayed for eotaxin, IL-8, and RANTES proteins with ELISA. Reverse transcription-PCR was also performed.

RESULTS

TNF-alpha induced production of eotaxin, IL-8, and RANTES in a concentration-dependent manner. Both IL-4 and IL-13 synergistically enhanced TNF-alpha-induced eotaxin production, whereas IL-8 production induced by TNF-alpha was significantly down-regulated by the T(H)2-derived cytokines. IFN-gamma, a T(H)1 cytokine, counteracted the enhancing effects of IL-4 and IL-13 on eotaxin production. RANTES production by TNF-alpha was not affected by IL-4 and IL-13 but was markedly enhanced by IFN-gamma.

CONCLUSIONS

These results suggest that T(H)2 cytokines are involved in preferential recruitment of eosinophils in bronchial asthma by enhancing eotaxin and reducing IL-8 production from bronchial epithelial cells and that T(H)1 cytokines counteract the effects of T(H)2 cytokines by reducing eotaxin production.

An in vitro comparison of commonly used topical glucocorticoid preparations

BACKGROUND

Glucocorticoids (GC) are potent inhibitors of peripheral blood eosinophil, basophil, and airway epithelial cell function.

OBJECTIVES

We compared in vitro the inhibitory activity of synthetic GC used for topical treatment in asthma and rhinitis on basophil histamine release (HR), eosinophil viability, and expression of vascular cell adhesion molecule-1 (VCAM-1) in the human bronchial epithelial cell line BEAS-2B.

METHODS

Cells were treated for 24 hours with increasing concentrations (range 10(-13) to 10(-6) mol/L) of fluticasone propionate (FP), mometasone furoate (MF), budesonide (BUD), beclomethasone dipropionate (BDP), triamcinolone acetonide (TAA), hydrocortisone (HC), or dimethyl sulfoxide diluent before challenge. HR was measured by a fluorometric assay, viability of purified eosinophils was assessed by erythrosin B dye exclusion, and expression of VCAM-1 was measured by flow cytometry.

RESULTS

GC induced a concentration-dependent inhibition of anti-IgE-induced HR. Maximum inhibition ranged from 59. 7% to 81%, with a rank order of GC potency of FP > MF > BUD > BDP congruent with TAA >> HC. Three-day treatment of eosinophils with GC concentration-dependently inhibited IL-5-induced eosinophil viability, with a rank of potency almost identical to that observed with basophil HR. The rank order of potency of GC for inhibition of the expression of VCAM-1 in BEAS-2B cells was MF congruent with FP >> BUD > TAA > HC congruent with BDP. Inhibitory concentration of 50% values revealed that epithelial cells were the most sensitive and eosinophils were the least sensitive.

CONCLUSIONS

These data, combined with information on pharmacodynamics of these drugs in vivo, may be useful in estimating GC local anti-inflammatory effects.

Inhibition of VCAM-1 expression in human bronchial epithelial cells by glucocorticoids

We have demonstrated previously that cytokines induce surface expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) on BEAS-2B bronchial epithelial cells in vitro. The present studies demonstrate glucocorticoid inhibition of cytokine-induced VCAM-1 expression as detected using flow cytometry and Northern blot analysis. Several commonly used inhaled glucocorticoids were tested for their ability to inhibit VCAM-1 and ICAM-1 expression. All glucocorticoids tested inhibited VCAM-1 expression in a dose-dependent manner. No inhibition of ICAM-1 expression was observed. The most potent of the glucocorticoids tested for inhibition of VCAM-1 expression were mometasone furoate and fluticasone propionate (FP), which had IC50 values (i.e., concentrations at which each glucocorticoid produced 50% inhibition) of under 10 pM. Budesonide, triamcinolone acetonide, and beclomethasone dipropionate (BDP) had intermediate potency, and hydrocortisone and the BDP metabolite beclomethasone-17-monopropionate were the least potent of the steroids tested. Kinetic analysis of the ability of FP to inhibit VCAM-1 expression revealed that preincubation with FP for 3 h completely inhibited VCAM-1 expression induced by tumor necrosis factor-alpha (TNF-alpha). FP inhibited VCAM-1 expression by 50% even when added as late as 6 h after stimulation with TNF-alpha. Using Northern blot analysis, we confirmed inhibition of VCAM-1 and ICAM-1 messenger RNA (mRNA) expression by FP. Pretreatment with FP (10(-11) M to about 10(-7) M, 24 h) inhibited TNF-alpha-induced VCAM-1 mRNA expression in BEAS-2B in a dose-dependent manner, but did not inhibit expression of ICAM-1 mRNA. Studies with actinomycin D indicate that FP treatment accelerated the degradation of TNF-alpha-induced VCAM-1 mRNA. FP (10(-7) M) also inhibited VCAM-1 mRNA expression induced by TNF-alpha in primary human bronchial epithelial cells as assessed by reverse transcription-polymerase chain reaction. These results suggest that suppression of epithelial VCAM-1 expression by glucocorticoids may contribute to their anti-inflammatory effects.

Clinical utility of serum levels of eosinophil cationic protein (ECP) for monitoring and predicting clinical course in childhood asthma

BACKGROUND

The concentration of ECP in serum has been proposed as a marker of airway inflammation in asthma. However, its clinical significance is still to be determined.

OBJECTIVES

This study was performed to determine whether concentration of ECP in serum reflects clinical status in asthma and can serve as a predictive parameter.

METHODS

Cross-sectional analysis was performed in 28 children with asthma. A total of 91 blood samples was obtained to determine levels of ECP in serum and eosinophil counts. Forced expiratory volume in 1 s was also determined at the time of the sampling. Data were analysed on the basis of asthma symptoms in the 4 weeks before and the 4 weeks after sampling.

RESULTS

Serum levels of ECP were significantly lower in patients who had been asymptomatic for 3 or 4 weeks before sampling than in patients who had been symptomatic or asymptomatic for only 1 or 2 weeks. In the former group, serum levels of ECP were higher when patients became symptomatic after sampling than when they remained stable, a finding that suggests that serum levels of ECP may have a predictive value in certain situations. Although the concentration of ECP in serum was not proved to be predictive in the latter symptomatic group, the concentration of ECP was significantly lower when measured again 4 weeks later when the patients' symptoms had resolved. In contrast, levels of ECP were unchanged when patients remained symptomatic, a finding that suggests serum levels of ECP may reflect the clinical response to therapy.

CONCLUSIONS

Serum ECP may be a useful marker for monitoring and predicting the clinical course in asthma.

Phenotyping and cytokine regulation of the BEAS-2B human bronchial epithelial cell: demonstration of inducible expression of the adhesion molecules VCAM-1 and ICAM-1

Airway epithelium may actively participate in inflammatory responses, such as occur in asthma. The presence and regulation of surface molecules on the airway epithelium, however, is incompletely understood. We have determined the phenotype of the human bronchial epithelial cell line BEAS-2B by flow cytometry. We confirmed previous observations that human bronchial epithelial cells constitutively express CD29, CD44, CD49a, CD49b, CD49c, CD49d, CD49e, CD49f, CD51, CD54 (ICAM-1), CD61, and HLA class 1. BEAS-2B cells were also found to constitutively express CD9, CD13, CD15, CD15s, CD23, CD33, CD36, CD40, CD41b, CD42b, CD48, CD50, CD71, and CD102 (ICAM-2). Culture of BEAS-2B cells with tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta (1 ng/ml) was found to enhance intercellular adhesion molecule-1 (ICAM-1) expression (several fold) and induce de novo CD106 [vascular cell adhesion molecule-1 (VCAM-1)] expression. TNF-alpha or IL-1beta did not change the expression of CD9, CD13, CD16, CD23, CD29, CD31, CD32, CD35, CD45, CD61, or CD64 in BEAS-2B cells. IL-4 (1 ng/ml) also induced expression of VCAM-1 (1.5-fold) but not ICAM- expression while interferon-gamma (1 ng/ml) enhanced only ICAM-1 expression (2-fold). Maximal VCAM-1 expression was obtained with the combination of TNF-alpha and IL-4 (8-fold). Using Northern blot hybridization analysis, ICAM-1 and VCAM-1 mRNA was detected in BEAS-2B cells stimulated with cytokines. VCAM-1 on stimulated BEAS-2B was functionally active as determined by adhesion of purified eosinophils and blockade with specific antibodies. Primary isolates of bronchial epithelial cells produced detectable levels of VCAM-1 protein and mRNA as detected by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively. These results suggest that cytokine activation induces expression of ICAM-1 and VCAM-1 on airway epithelium, an event which may influence leukocyte infiltration and activation.

IL-5 as a strong secretagogue for human eosinophils

The ability of IL-5 to induce eosinophil degranulation was investigated. Peripheral blood eosinophils from patients with mildly allergic individuals were isolated with CD16- selection method. Eosinophils were then incubated with interleukin-5 (IL-5) (0.1-100 ng/ml) for 1-48 h and EPX in the supernatants were measured with RIA. We found that IL-5 induced significant amount of eosinophil protein X in a concentration-dependent manner at 24 h. Eosinophil viability was about 90% either in the presence or absence of IL-5 at 24 h. Eosinophils stimulated with IL-5 adhered to the plate. Anti-CD18 mAb blocked adhesion and degranulation induced by IL-5. Dexamethasone and TGFbeta significantly inhibited degranulation in a concentration-dependent manner. These results suggest that IL-5 may be a strong secretagogue for eosinophils, that adhesion via beta2 integrin is a requisite for degranulation, and that the anti-inflammatory effect of corticosteroids and TGFbeta may be exerted at least in part, through the inhibition of eosinophil degranulation.

[The relationship of eosinophil viability enhancing activity in sputum and clinical symptoms in asthma]

We studied the correlation of eosinophil viability enhancing activity (EVEA) in sputum from asthmatic children and clinical symptoms. Sputum from asthmatic children and equal volume of saline were mixed with a Vortex mixer and centrifuged at 40000 G. Clear supernatants were obtained and filtered with 0.22 micron membrane filter. Periphral blood eosinophils purified by Percoll density gradient centrifugation and CD16 negative selection/ immunomagnetic beads technique were incubated with sputum extract for 4 days. Eosinophil viability was examined by staining the cells with fluorescen diacetate and propidium iodide and expressed as eosinophil viability enhancing activity (EVEA). Eosinophil cationic protein (ECP) concentrations in sputum were also measured by a radioimmunoassay. Correlation between EVEA in sputum and pulmonary functions, attack score, treatment score, or sputum ECP was determined by Spearman correlation test. Sputum EVEA was correlated 1) inversely with pulmonary functions on sampling, 2) with attack score of 2 weeks period before sampling, 3) with treatment score of 1 month to 1 week before and 1 to 2 weeks after sampling, and 4) with sputum ECP in individual cases. Sputum EVEA may serve as a suitable parameter for monitoring airway inflammation in asthma.

Inhibitory effect of transforming growth factor beta 1 on cytokine-enhanced eosinophil survival and degranulation

The effects of transforming growth factor (TGF) beta 1 on cytokine-enhanced eosinophil survival and degranulation were investigated in vitro to determine whether it is an inhibitory regulator of allergic inflammation. Peripheral blood eosinophils purified by Percoll density gradient centrifugation and the CD16 negative selection technique were incubated in the presence of eosinophil-activating cytokines (interleukin-5 (IL-5), IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-gamma) with and without TFG-beta 1 for 1-3 days. On day 1, eosinophil protein X release was measured by radioimmunoassay. Eosinophil viability on day 3 was determined by staining the cells with fluorescein diacetate and propidium iodide, and on the same day DNA was extracted and subjected to gel electrophoresis to test for fragmentation. TGF-beta 1 significantly inhibited eosinophil survival enhanced by IL-5, IL-3, GM-CSF and IFN-gamma in a dose-dependent manner. The inhibitory effects of TGF-beta 1 on IL-5-enhanced survival was partially reversed by high concentrations of IL-5 and was completely neutralized with anti-TGF-beta antibody. IL-5 inhibited DNA fragmentation of eosinophils in vitro. TGF-beta reversed the effect of IL-5, indicating that TGF-beta 1 activates the pathway of apoptosis. TGF-beta 1 significantly suppressed eosinophil protein X release induced by IL-5. These results suggest that TGF-beta 1 may play a role in the modulation of allergic inflammation.

Consecutive cerebral MRI findings of acute relapsing disseminated encephalomyelitis

A seven year old girl with acute relapsing disseminated encephalomyelitis (ARDEM) was observed with serial magnetic resonance imaging (MRI) examination. She had the first encephalomyelitis episode at the age of 2 years 9 months. She entered remission with steroid therapy. She suffered a recurrence at the age of 7. Steroid therapy was instituted and consecutive magnetic resonance imaging (MRI) was performed. In spite of rapid improvement of neurological abnormality with steroid and steroid pulse therapy, disseminated high intensity lesions in T2-weighted imaging which were considered as demyelination remained for a long time. Magnetic resonance imaging seems to be most suitable for evaluating the clinical condition and long-term follow-up of ARDEM.

[Inhibitory effect of TGF-beta 1 on cytokine-enhanced eosinophil survival]

TGF-beta 1 has many biological activities in various cell types and is regarded as a multifunctioning regulator of cell growth. We studied the effect of TGF-beta 1 on cytokine-enhanced eosinophil survival in vitro. Eosinophils were purified from patients with mild atopic dermatitis by Percoll density gradient centrifugation and the CD16 negative selection/immunomagnetic beads technique. Eosinophil purity was greater than 95%. The purified eosinophils were incubated in the presence of eosinophil-activating cytokines (IL-5, IL-3, GM-CSF, IFN-gamma) with and without TGF-beta 1 for 3 days. Eosinophil viability was determined by staining the cells with fluorescein diacetate and propidium iodide. Without cytokine, most eosinophils died by day 3 in culture, but human recombinant IL-5, IL-3, GM-CSF, and IFN-gamma enhanced eosinophil survival in a dose-dependent manner. To test the effect of TGF-beta 1 on enhanced eosinophil survival, eosinophils were cultured with activating cytokine and TGF-beta 1. TGF-beta 1 inhibited eosinophil survival in a dose-dependent manner. The inhibitory effects of TGF-beta 1 on IL-5 enhanced survival was partially reversed by high concentrations of IL-5 and was completely neutralized with anti-TGF-beta antibody. Moreover, the apoptosis of eosinophils induced by TGF-beta 1 was determined with the assay of DNA fragmentation on agarose gel electrophoresis. It is possible that TGF-beta 1 activates the pathway of apoptosis. The results suggest that TGF-beta 1 may play a crucial role in the regulation of allergic inflammation.

Mechanism of eosinophil infiltration in the patient with subcutaneous angioblastic lymphoid hyperplasia with eosinophilia (Kimura's disease). Mechanism of eosinophil chemotaxis mediated by candida antigen and IL-5

Kimura's disease is a chronic granulomatous disease of unknown etiology. Although eosinophilia is one of the characteristic features in this disease, little is known about the mechanism of eosinophilia. In the present study it was demonstrated that interleukin-5 (IL-5) was produced and released from the site of a granuloma and lymph nodes after stimulation with candida antigen. It was also shown that peripheral blood eosinophils from patients with Kimura's disease contained a large proportion of hypodense eosinophils and that their viability was prolonged. These results strongly suggest that locally produced IL-5 induced by candida antigen contributes to the eosinophilia in this disease.

Interferon-gamma induces interleukin-3 release from peripheral blood eosinophils

Interferon-gamma (IFN-gamma) upregulates eosinophil effector functions and prolongs the in vitro survival of eosinophils. We examined the possible capacity of IFN-gamma to stimulate eosinophils to produce eosinophil-activating cytokines. Eosinophils purified from mild atopic volunteers were cultured with 100 U/ml IFN-gamma. Viability of eosinophils was counted and supernatants were tested for the presence of cytokines by neutralization of eosinophil viability-enhancing activity with specific antibodies to IFN-gamma, interleukin-5 (IL-5), IL-3, or granulocyte-macrophage colony-stimulating factor (GM-CSF). IFN-gamma-enhanced eosinophil viability was up to 95% on the 4th day of culture. Pretreatment with anti-IL-3 antibody partially blocked the IFN-gamma-enhanced eosinophil survival. IFN-gamma-stimulated eosinophil supernatants had eosinophil survival. IFN-gamma-stimulated eosinophil supernatants had eosinophil viability-enhancing activity that was blocked by pretreatment not only with anti-IFN-gamma but also with anti-IL-3. Antibodies to IL-5 or GM-CSF did not have the blocking effect. To further confirm the production of IL-3 by eosinophils, we performed reverse transcription polymerase chain reaction (RT-PCR) for IL-3 messenger RNA (mRNA) in IFN-gamma-stimulated eosinophils. Significant IL-3 mRNA expression in eosinophils was observed at 6 h of incubation with IFN-gamma. These results suggest that IFN-gamma stimulates the autocrine function of eosinophils and may play an important role in allergic inflammation.