[Production of innervated bronchial epithelium from a blood sample]. / Fabrication d'un épithélium bronchique innervé à partir d'une prise de sang.

Asthma is a frequent respiratory disease, with severe asthma occurring in 3 to 5% of cases. Chronic inflammation of the bronchial epithelium is essential to its pathophysiology. When activated by the bronchial environment, the peripheral sensory nervous system contributes to inflammation of the airways. However, due to a lack of reliable models, the mechanisms of action remain largely unknown. Using induced pluripotent stem cells reprogrammed from blood cells, we have set up a model of bronchial epithelium innervated by sensory neurons. This model will ensure better understanding of the mechanisms of action underlying neurogenic inflammation.

Activation of the lung S1P(1) receptor reduces allergen-induced plasma leakage in mice.

BACKGROUND AND PURPOSE: It has been suggested that intratracheal administration of the immunomodulator, FTY720, could have anti-inflammatory effects without causing a decrease in blood lymphocyte counts. However, the receptor responsible for this effect has not been defined. EXPERIMENTAL APPROACH: We have described, in a mouse model of allergen-induced inflammation, the use of proton magnetic resonance imaging to non-invasively assess lung fluid accumulation and inflammation. Here, we used this model to investigate the sphingosine-1-phosphate (S1P) receptor responsible for the anti-inflammatory effect of FTY720. KEY RESULTS: When given intranasally, FTY720 (3 and 10 microg.kg(-1)) inhibited by approximately 50% the allergen-induced accumulation of fluid in the lung detected by magnetic resonance imaging, but had no effect on the cellular inflammation in the airway space or on circulating blood lymphocytes. Inhibition of the infiltration of inflammatory cells into the airways was only observed at a dose of FTY720 that induced lymphopenia (100 microg.kg(-1)). Similar results were observed in S1P(3)-deficient mice. The effect of FTY720 was mimicked by intranasal treatment of wild-type mice with a S1P(1)-specific agonist, AUY954. CONCLUSIONS AND IMPLICATIONS: Thus, in contrast to previously published work, our results suggest that systemic exposure of FTY720 is necessary to obtain an airway anti-inflammatory effect. On the contrary, inhibition of the allergen-induced accumulation of fluid in the lung, via activation of the S1P(1) receptor, is obtainable without systemic effects.

The nerve growth factor and its receptors in airway inflammatory diseases.

The nerve growth factor (NGF) belongs to the neurotrophin family and induces its effects through activation of 2 distinct receptor types: the tropomyosin-related kinase A (TrkA) receptor, carrying an intrinsic tyrosine kinase activity in its intracellular domain, and the receptor p75 for neurotrophins (p75NTR), belonging to the death receptor family. Through activation of its TrkA receptor, NGF activates signalling pathways, including phospholipase Cgamma (PLCgamma), phosphatidyl-inositol 3-kinase (PI3K), the small G protein Ras, and mitogen-activated protein kinases (MAPK). Through its p75NTR receptor, NGF activates proapoptotic signalling pathways including the MAPK c-Jun N-terminal kinase (JNK), ceramides, and the small G protein Rac, but also activates pathways promoting cell survival through the transcription factor nuclear factor-kappaB (NF-kappaB). NGF was first described by Rita Levi-Montalcini and collaborators as an important factor involved in nerve differentiation and survival. Another role for NGF has since been established in inflammation, in particular of the airways, with increased NGF levels in chronic inflammatory diseases. In this review, we will first describe NGF structure and synthesis and NGF receptors and their signalling pathways. We will then provide information about NGF in the airways, describing its expression and regulation, as well as pointing out its potential role in inflammation, hyperresponsiveness, and remodelling process observed in airway inflammatory diseases, in particular in asthma.

Anti-proliferative effect of Euphorbia stenoclada in human airway smooth muscle cells in culture.

The ethanolic extract of a Malagasy species Euphorbia stenoclada (ES) (Euphorbiaceae), traditionally used as a herbal remedy against asthma and acute bronchitis, was tested to evaluate possible anti-proliferative activity on human airway smooth muscle cells (HASMC). The ES ethanolic extract totally abolished the interleukin-1beta (IL-1beta) induced proliferation of HASMC (IC(50)=0.73+/-0.08 microg/mL). No cytotoxic effect was observed up to 20 microg/mL. A bioassay-guided fractionation of the ethanolic extract was performed by reversed-phase (RP) flash chromatography, giving five fractions (FA to FE) where fraction FE was the only active one (IC(50)=0.38+/-0.02 microg/mL). The purification of this bioactive fraction FE was carried out by RP-HPLC affording six sub-fractions 1-6, and only sub-fraction 5 kept the anti-proliferative activity. Its major constituent was identified as quercetin (IC(50)=0.49+/-0.12 microg/mL) by means of HPLC/UV/MS and co-elution with the authentic standard. Quercitrin was also identified in the fraction FE but was inactive. A structure-activity relationship with flavonols determined that methylation reduced the anti-proliferative activity whereas glycosylation abolished it. The present study shows that the anti-proliferative properties of Euphorbia stenoclada are mediated through the presence of quercetin that may explain the traditional use of this plant as a remedy against asthma.

Effect of glucocorticoids on stem cell factor expression in human asthmatic bronchi.

BACKGROUND: Stem cell factor (SCF) is a major mast cell growth factor promoting differentiation, chemotaxis as well as inhibition of apoptosis of mast cells. Regulation of SCF expression by glucocorticoids has not yet been reported in human asthmatic bronchi. OBJECTIVE: To evaluate SCF mRNA and protein expression in biopsy specimen and bronchoalveolar lavage fluid, respectively, and to determine the mast cell numbers in biopsy sections from control and asthmatic subjects treated or not with glucocorticoids. METHODS: Volunteers were recruited out of pollen season. Asthmatic patients were allergic to common allergen extracts including grass and tree pollen, cat, dog or mite; three volunteers had non-allergic asthma. Mast cell numbers were counted after anti-human tryptase immunolabelling. SCF mRNA was quantified by real-time fluorescent PCR (LightCycler) after reverse transcription, and SCF protein was measured by ELISA. RESULTS: Asthmatic patients not treated with glucocorticoids showed a 5.8-, 1.8- and 3.1-fold significant increase in SCF mRNA, protein levels and mast cell numbers, respectively, compared with healthy volunteers of the control group (7.8 and 1.3 pg/mug SCF mRNA/GAPDH; 99.8+/-11.5 and 56.0+/-11.0 pg/mL SCF protein; 103+/-21 and 33+/-8 mast cells/mm(2), respectively; P<0.05). In asthmatic patients treated with glucocorticoids, a significant decrease of SCF mRNA, protein levels and mast cell numbers was observed as compared with untreated asthmatic patients (1.1 pg/microg mRNA; 62.0+/-10.3 pg/mL SCF protein and 39+/-13 mast cells/mm(2); P<0.05), reaching levels comparable to those of the control group. CONCLUSION: Our study shows that SCF is expressed in the bronchus in humans in vivo. This expression is increased in asthma, and is parallel to the increased mast cell numbers in the airways. Both increases were normalized in glucocorticoid-treated patients, strongly suggesting an involvement of SCF in the mast cell-associated asthmatic disease.

Nerve growth factor is released by IL-1beta and induces hyperresponsiveness of the human isolated bronchus.

Nerve growth factor (NGF) is a neurotrophic factor essential for the development and survival of neurons, and is also an important mediator of inflammation. It is released by airway cells stimulated by interleukin (IL)-1beta. As IL-1beta induces airway hyperresponsiveness (AHR) to the tachykinin NK-1 receptor agonist [Sar9,Met(O2)11]-substance P in human isolated bronchi, the aim of this study was to determine whether IL-1beta was able to induce NGF release from isolated bronchi, and whether NGF might participate into IL-1beta-induced AHR. IL-1beta (10 ng x mL(-1); 21 degrees C; 15 h) increased the release of NGF from human isolated bronchi in vitro, and, in organ bath studies, the response of human bronchi to [Sar9,Met(O2)11]-substance P (0.1 microm). A significant correlation was found between these responses. AHR induced by IL-1beta was abolished by a blocking anti-human NGF antibody. Finally, NGF (1 ng x mL(-1); 37 degrees C; 0.5 h) by itself induced a significant increase in [Sar9,Met(O2)11]-substance P responsiveness. By contrast, it did not change the maximal contraction to acetylcholine. In conclusion, the present study clearly demonstrated that nerve growth factor may participate in the airway hyperresponsiveness induced by interleukin-1beta, which supports the neuro-immune cross-talk that may be active in the development of hyperresponsiveness in the human airways, and suggests nerve growth factor is active in the airways in asthma.

Dose-dependent effects of endotoxins on allergen sensitization and challenge in the mouse.

BACKGROUND: Levels of endotoxins greatly differ according to environmental settings. OBJECTIVE: To study the effect of lipopolysaccharide (LPS) at increasing doses (0.1-1000 ng) on allergen sensitization and challenge in the mouse. METHODS: Mice were sensitized systemically and challenged locally with ovalbumin (OVA) in the presence or absence of LPS. Inflammation was assessed by determining total and differential cell counts and T-helper type 2 (Th)2 cytokine (IL-4 and IL-5) levels in bronchoalveolar lavage fluid (BALF). Total and OVA-specific IgE levels were quantified in serum. Airway hyper-responsiveness (AHR) was assessed by whole-body barometric plethysmography. RESULTS: Administered prior to sensitization, LPS at 100 or 1000 ng dose-dependently decreased allergen- induced total and OVA-specific IgE, airway eosinophilia and Th2 cytokines in BALF, without changing AHR. Administered during OVA challenge, LPS at 1 ng (an infra-clinical dose) or 100 ng (a dose triggering neutrophilia) enhanced airway eosinophilia, without affecting IgE levels or AHR. CONCLUSION: Our data clearly demonstrate that exposure to LPS influences allergen-induced IgE production and airway eosinophilia in a time and dose-dependent manner, preventing IgE production and development of eosinophilia when administered during allergen sensitization at high doses, and inducing exacerbation of eosinophilia when administered upon allergen challenge at low doses, including infra-clinical doses.

Neurogenic mechanisms in bronchial inflammatory diseases.

Neurogenic inflammation encompasses the release of neuropeptides from airway nerves leading to inflammatory effects. This neurogenic inflammatory response of the airways can be initiated by exogenous irritants such as cigarette smoke or gases and is characterized by a bi-directional linkage between airway nerves and airway inflammation. The event of neurogenic inflammation may participate in the development and progression of chronic inflammatory airway diseases such as allergic asthma or chronic obstructive pulmonary disease (COPD). The molecular mechanisms underlying neurogenic inflammation are orchestrated by a large number of neuropeptides including tachykinins such as substance P and neurokinin A, or calcitonin gene-related peptide. Also, other biologically active peptides such as neuropeptide tyrosine, vasoactive intestinal polypeptide or endogenous opioids may modulate the inflammatory response and recently, novel tachykinins such as virokinin and hemokinins were identified. Whereas the different aspects of neurogenic inflammation have been studied in detail in laboratory animal models, only little is known about the role of airway neurogenic inflammation in human diseases. However, different functional properties of airway nerves may be used as targets for future therapeutic strategies and recent clinical data indicates that novel dual receptor antagonists may be relevant new drugs for bronchial asthma or COPD.

In vivo evaluation of a reverse water-in-fluorocarbon emulsion stabilized with a semifluorinated amphiphile as a drug delivery system through the pulmonary route.

The potential of a reverse water-in-fluorocarbon (w-in-FC) emulsion stabilized with a semifluorinated amphiphile, namely C8F17(CH2)11OP(O)[N(CH2CH2)2O]2 (F8H11DMP) for drug delivery through intrapulmonary administration was investigated in the mouse. This study involved assessment of the effect of single or repeated intranasal instillations of a plain emulsion on lung tissue integrity, and evaluation of blood glucose levels in mice treated with an insulin-loaded emulsion. When instilled intranasally to mice, the plain emulsion did not alter lung tissue integrity, as demonstrated by histological staining, and did not induce any airway inflammatory reaction. Treated mice exhibited decreased body weight within the 3-4 days that followed the first emulsion administration, but this decrease was reversible within few days. Mice instilled intranasally with the insulin-loaded emulsion displayed decreased blood glucose levels within the 20 min that followed the administration, thus demonstrating the potential of the reverse w-in-FC emulsion stabilized with F8H11DMP to systemically deliver drugs, including peptides, upon lung administration.

[Nerve growth factor (NGF) in inflammation and asthma]. / Le facteur de croissance des nerfs (NGF) dans l'inflammation et l'asthme.

INTRODUCTION: The nerve growth factor (NGF) is known as a factor involved in neuronal growth and survival. From recent studies it may also be considered as a mediator of inflammation, in particular in the airways. STATE OF ART: Several animal studies have shown that NGF may increase the sensory innervation, and participate in the bronchial hyperresponsiveness and inflammation observed in the airways of asthmatic patients. Different cell types are capable of secreting NGF: inflammatory cells that infiltrate the bronchial mucosa, and structural cells such as epithelial cells, smooth muscle cells and pulmonary fibroblasts. Furthermore, increased NGF levels have been detected in the bronchoalveolar lavage fluid from asthmatic patients. PERSPECTIVES AND CONCLUSION: Altogether, these results suggest that NGF may play a role in inflammation, bronchial hyperresponsiveness and airway remodelling in asthma, and may lead to a better understanding of the mechanisms occurring in chronic inflammatory diseases, in particular asthma.

Expression of tyrosine hydroxylase and neuropeptide tyrosine in mouse sympathetic airway-specific neurons under normal situation and allergic airway inflammation.

BACKGROUND: The traditional neurotransmitter catecholamine and the neuropeptide tyrosine in sympathetic airway nerves have been proposed to be involved in the pathogenesis of airway diseases. OBJECTIVE: The aim of the present study was to investigate the effect of allergic airway inflammation on the expression of catecholamine enzyme tyrosine hydroxylase (TH), neuropeptide tyrosine (NPY) and tachykinins in mouse sympathetic airway ganglia. METHODS: Using neuronal tracing in combination with immunohistochemistry, the present study was designed to characterize TH, NPY and tachykinin profiles of superior cervical (SCG) and stellate ganglia after allergen challenge. RESULTS: The vast majority of fast blue-labelled SCG neurons (allergen: 97.5+/-1.22% (mean+/-SEM) vs. controls: 94.5+/-1.48%, P=0.18) and stellate neurons (allergen: 95.3+/-1.01% vs. controls: 93.6+/-1.33%, P=0.34) were immunoreactive for TH. Of the TH immunoreactive and fast blue-labelled SCG neurons, 52.0+/-1.01% allergen vs. 51.2+/-3.58% controls (P=0.83) and stellate neurons, 57.3%+/-0.97 allergen vs. 56.4+/-1.65% controls (P=0.64) were positive for TH only but not NPY, whereas 45.3+/-1.05% allergen vs. 43.3+/-1.18% controls (P=0.47) of fast blue-labelled SCG neurons and 37.9+/-0.86% allergen vs. 37.1+/-1.24% controls (P=0.62) of fast blue-labelled stellate neurons were immunoreactive for both TH and NPY immunoreactivities. There was a trend of an increase, but not significant one, in the percentage of TH-/NPY-immunoreactive and fast blue-labelled neurons in allergen-treated animals in comparison with the controls. Tachykinins, however, were not expressed by sympathetic neurons and were also not induced in sympathetic neurons after allergen challenge. CONCLUSION: The present study indicates that allergic airway inflammation does not alter the expression of noradrenalin and NPY in sympathetic ganglia and also shows that sympathetic neurons do not respond to allergic airway inflammation with tachykinins induction. However, a participation of catecholamine and NPY in the pathogenesis of allergic airway inflammation cannot be excluded in the present study as a higher neurotransmitter output per neuron following allergen challenge could be possible.

Evaluation of cytotoxicity of new semi-fluorinated amphiphiles derived from dimorpholinophosphate.

Water-in-fluorocarbon reverse emulsions and microemulsions stabilized by semi-fluorinated amphiphiles derived from the dimorpholinophosphate polar head group, C(n)F(2n+1)(CH(2))(m)OP(O)[N(CH(2)CH(2))(2)O](2) (FnHmDMP), are being investigated as new delivery systems for drugs or genetic materials into the lung. Since information related to the toxicity of fluorinated surfactants is still very limited, we evaluated herein the cytotoxicity of a series of FnHmDMP (n=4, 6, 8 and 10 and m=2, 5, and 11). Both solutions of FnHmDMP in fluorocarbons, and reverse water-in-fluorocarbon emulsions stabilized by FnHmDMP were assessed in order to determine the relation between surfactant structure and cell toxicity, and select the most innocuous emulsifier. A first short-term evaluation on mouse fibroblasts using a viability/cytotoxicity assay indicated that amphiphiles (in solution) with a chain length longer than C12 exhibit less toxicity than amphiphiles with shorter chain. Moreover cytotoxicity decreased also with length of the fluorinated segment. The protective effect of the fluorinated chain was strongly supported by the fact that the hydrogenated analog, C(15)H(31)OP(O)[N(CH(2)CH(2))(2)O](2) (H15DMP), was highly toxic. Qualitative evaluation on human lung epithelial cells (HLEC) using a colorimetric method (Mayer's hematoxylin) confirmed that amphiphiles (in solution) with longer chain were the least cytotoxic. The protective effect of the fluorinated chain appeared, however, to be significant only at low amphiphile concentrations (0.1% w/v). In contrast, at higher concentrations (1% and 5% w/v), the total chain length was the determining factor. Quantitative evaluation of the least cytotoxic amphiphiles using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method then showed that F10H11DMP (in solution) was harmless until its solubility limit (1% w/v); cell growth was even enhanced due to improved oxygenation provided by the fluorocarbon phase. F8H11DMP exhibited some cytotoxicity at both 1% and 5% w/v, but the toxicity appeared to level off with concentration. Reverse water-in-perfluorooctyl bromide (PFOB) emulsions stabilized by either F10H11DMP or F8H11DMP were found to be non-cytotoxic. In conclusion, the present evaluation indicates that the cytotoxicity of FnHmDMP depends on both total and fluorinated amphiphile chain length, and leads us to select F8H11DMP and F10H11DMP as the less cytotoxic amphiphiles among a series of FnHmDMP compounds. Furthermore, water-in-fluorocarbon emulsions stabilized with F8H11DMP and F10H11DMP appeared to be non-cytotoxic towards HLEC in culture.

Nerve growth factor levels and localisation in human asthmatic bronchi.

Nerve growth factor (NGF) has recently been suggested to be an important mediator of inflammation. In support of this, serum levels of NGF have been shown to be enhanced in asthmatics. However, it has not yet been shown whether the levels of NGF are also altered locally in asthmatic airways, when compared with healthy subjects, and the localisation of potential sources of NGF in the human bronchus have not yet been described. The aim of the present study was to assess NGF levels in bronchoalveolar lavage fluid (BALF) from asthmatics and to compare them to those of control subjects. Furthermore, the authors wanted to localise potential sources of NGF in bronchial tissue, and to number NGF-immunopositive infiltrating cells in the bronchial submucosa. BALF and bronchial biopsies were obtained from seven control subjects and seven asthmatic patients by fibreoptic bronchoscopy. NGF protein levels were quantified by enzyme-linked immunosorbent assay in BALF. NGF localisation was examined by immunohistochemistry on bronchial biopsy sections. The asthmatics exhibited significantly enhanced NGF levels in BALF. Intense NGF-immunoreactivity was observed in bronchial epithelium, smooth muscle cells and infiltrating inflammatory cells in the submucosa, and to a lesser extent in the connective tissue. The asthmatics exhibited a higher number of NGF-immunoreactive infiltrating cells in the bronchial submucosa than control subjects. This study provides evidence that nerve growth factor is locally produced in the airways, and shows that this production is enhanced in asthmatics. These findings suggest that nerve growth factor is produced by both structural cells and infiltrating inflammatory cells in human bronchus in vivo, and the authors suggest that the increase in nerve growth factor protein in bronchoalveolar lavage fluid observed in asthmatic patients may originate both from structural cells, producing increased nerve growth factor levels in inflammatory conditons, and from the increase in nerve growth factor-immunopositive cells determined in the bronchial submucosa.

Upregulation of nerve growth factor expression by human airway smooth muscle cells in inflammatory conditions.

Recent studies have suggested that nerve growth factor (NGF) may play a role in inflammation and bronchial hyperresponsiveness in asthma. Neither the types of cells that produce NGF in the human airways nor the effect of inflammation on NGF expression are clear. The two-fold aim of the present study was to determine whether airway smooth muscle produces NGF in vitro, and, if so, whether the pro-inflammatory cytokine interleukin-1beta (IL-1beta) affects this expression. Human airway smooth muscle cells in culture were incubated in the presence or absence of IL-1beta. NGF production was measured by enzyme-linked immunosorbent assay. NGF messenger ribonucleic acid (mRNA) was measured using a specific real-time fluorescent polymerase chain reaction technique, and expressed in relation to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels. Human airway smooth muscle cells in vitro expressed NGF constitutively (21.4+/-7.8 pg x mL(-1); 14.6+/-5.4 pg NGF complementary deoxyribonucleic acid (cDNA) x pg GAPDH cDNA(-1) (mean+/-SEM)). Stimulation with IL-1beta (0.1-30 U x mL(-1)) for 24 h induced a dose-dependent increase in NGF production (22.1 pg x mL(-1) at 10 U x mL(-1); p<0.05). The IL-1beta (10 U x mL(-1))-induced increase in NGF expression was time-dependent. It was highest for NGF protein at 10 h (1.6-fold increase over control; p<0.001) and for NGF mRNA at 2.5 h (2.4-fold increase over control; p<0.05). In conclusion, the present study clearly shows that the human airway smooth muscle cell is a source of nerve growth factor, the expression of which is upregulated in inflammatory conditions, mimicked in vitro by the addition of interleukin-1beta.

Comparative activity of cetirizine and mizolastine on histamine-induced skin wheal and flare responses at 24 h.

AIMS: The aim of our study was to compare the activity of cetirizine 10 mg with that of mizolastine 10 mg vs placebo at 24 h after intake in healthy volunteers. METHODS: This was a double-blind, randomized, placebo controlled, three-way cross-over study with a wash-out period of 7 +/- 2 days between each period. The study included 36 healthy volunteers (18--50 years, mean age = 32 years; 9 males). The objective measurement was the cutaneous reactivity to increasing concentrations of histamine (0, 5, 10, 20, 40, 80, 160 mg ml(-1)) administered by prick tests. The reactivity was evaluated by the wheal and flare areas (mm2). The AUC (area under curves) values of the wheal and flare areas as a function of the log2 transformed histamine concentration were calculated for each subject and treatment, and compared. RESULTS: A highly significant treatment effect was evidenced both for wheal and flare responses (P = 0.0001). This indicates the good activity of both cetirizine 10 mg and mizolastine 10 mg in inhibiting skin wheal and flare reactions to histamine. In addition, the mean AUC values significantly differed between cetirizine and mizolastine (64.8 and 117.8 log2 (mg ml(-1)) x mm2 for wheal, and 939.4 and 2340.8 for flare, respectively; P = 0.0001), with a superior activity of cetirizine than mizolastine at 24 h after intake both on wheal and flare responses. The tolerance of cetirizine and mizolastine was good. The severity of the adverse events was never more than 'moderate', 'fatigue' being the most frequent reported symptom [cetirizine (6 subjects), placebo (3), mizolastine (5)], followed by 'somnolence' [cetirizine (0), placebo (1), mizolastine (3)]. There was no serious adverse event. CONCLUSIONS: This study shows that cetirizine (10 mg) suppresses skin reactivity to histamine more effectively than mizolastine (10 mg) 24 h after intake in healthy volunteers.

Nerve growth factor secretion by human lung epithelial A549 cells in pro- and anti-inflammatory conditions.

Nerve growth factor (NGF) has recently been presented as a possible effector of inflammation and bronchial hyperresponsiveness. However, the production of NGF in human airways as well as the regulation of its expression by inflammatory cytokines and glucocorticoids have received little attention. A549 epithelial cells were cultured in Dulbecco's modified Eagle's medium supplemented with 10% foetal bovine serum, and starved for 24 h. The effect of the pro-inflammatory cytokine interleukin-1beta (1-30 U/ml), and of the glucocorticoid dexamethasone (1 microM) on NGF secretion was studied and quantified by enzyme-linked immunosorbent assay (ELISA). In addition, NGF production within the cells was visualized by immunocytochemistry. Under basal conditions, A549 cells produced and secreted NGF (12.6+/-2.0 pg/ml). Stimulation by interleukin-1beta for 24 h induced a dose-dependent increase in NGF production (maximal at 10 U/ml with 59.6+/-3.5% increase, P<0.05). Dexamethasone (1 microM) markedly reduced the constitute NGF secretion by 44.9% (7.0+/-2.1 pg/ml, P<0.001). In addition, the interleukin-1beta-stimulated NGF secretion was inhibited to approximately the same low level (8.5+/-2.5 pg/ml, P<0.001). In conclusion, we here report that human airway A549 epithelial cells are capable of producing NGF. This production is positively regulated by the pro-inflammatory interleukin-1beta, and negatively regulated by dexamethasone.