IL-8 and airway neutrophilia in children with gastroesophageal reflux and asthma-like symptoms.

Gastroesophageal reflux (GER) may induce respiratory symptoms (RS) through inhalation of acid gastric contents. To characterize the airway inflammation associated with this condition, 20 children [7.4 (0.9) yr old] with "difficult to treat" RS and a positive 24-h oesophageal pH monitoring (pHm) were studied and bronchoalveolar lavage (BAL) performed. The control group included 10 children [7.3 (1.3) yr], non-atopics, with a respiratory clinical history similar to the cases but no reflux, as demonstrated by a negative 24-h oesophageal pHm. On BAL samples, in addition to inflammatory indexes, the lipid-laden macrophage (LLM) index was determined as index of gastric content inhalation. As compared to controls, GER children had higher neutrophil proportion (P=0.002), higher LLM index (P=0.004) and higher concentrations of interleukin (IL)-8 (P=0.005), myeloperoxidase (MPO) (P=0.001) and elastase (P=0.045) in BAL fluid. In GER children, but not in controls, neutrophil proportion significantly correlated with LLM index (r=0.65, P=0.002), with IL-8 (r=0.62, P=0.003) and MPO levels (r=0.54, P=0.014) but not with elastase concentrations. These results suggest an active pathogenetic role of IL-8 in the recruitment and activation of neutrophils in the airways of children with GER, respiratory symptoms and BAL findings suggestive of gastric content aspiration.

Concentration-dependent activity of mometasone furoate and dexamethasone on blood eosinophils isolated from atopic children: modulation of Mac-1 expression and chemotaxis.

Treatment of asthma with corticosteroids results in downregulation of eosinophilic airway inflammation. We evaluated in vitro the activity of an "inhaled" corticosteroid, mometasone furoate (MF), and of a "systemic" corticosteroid, dexamethasone (DEX), on eosinophil functions, i.e. adhesion molecule expression and cell chemotaxis. Partially purified blood eosinophils were obtained from 18 asthmatic subjects sensitized to house dust mites. The expression of the macrophage antigen (Mac)-1 (CD11b/CD18) was measured by specific monoclonal antibody (mAb) staining and flow cytometry analysis at baseline or after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or with recombinant human (rh) granulocyte macrophage-colony stimulating factor (GM-CSF) plus a mAb anti-human (ah) IgE low affinity receptor [FcepsilonRII or CD23]. Cell chemotaxis toward the complement fragment 5a (C5a) or rh interleukin (IL)-5 was evaluated in Boyden microchambers by light microscopy. Eosinophils showed a significant increase in Mac-1 expression after activation with fMLP or with rh GM-CSF plus ah CD23 mAbs (p<0.05, each comparison) and a remarkable chemotactic response to both C5a or rh IL-5 (p<0.001, each comparison). To test the inhibitory activity of MF and DEX on eosinophil functions, the cells were preincubated for 3 h with four concentrations (0.1, 1, 10 and 100 nM) of each of the two drugs, before being activated by fMLP or by rh GM-CSF plus ah CD23 mAbs or tested with C5a or with rh IL-5. Independently of the stimulus used, both Mac-1 expression and eosinophil migration were effectively downregulated by preincubation with MF or DEX at 1, 10 and 100 nM (p<0.05). The inhibitory activity on cell chemotaxis in response to both C5a or with rh IL-5 was higher for MF than DEX, but only at the highest concentration tested (p<0.05, each comparison). These data demonstrate that concentrations of MF similar to those obtained in vivo are highly effective in inhibiting eosinophil functions involved in airway inflammation.

Epithelial cells and fibroblasts: structural repair and remodelling in the airways.

Extensive lesions and changes in the architecture of the airway walls are commonly described in patients with respiratory infections, asthma, chronic bronchitis and interstitial lung diseases. Current knowledge identifies in airway epithelial cells and in fibroblasts the two cell types mainly involved in tissue repair after injury. During inflammatory respiratory disorders, extensive injury of airway epithelium may occur, with shedding of a large sheet of damaged cells in the bronchial and alveolar lumen but also with activation of the surviving epithelial cells and of the underlying fibroblasts. Indeed, besides acting as a physical and functional barrier to external agents, the epithelial surface of the bronchi has the capability to modulate the repair processes through the secretion of extracellular matrix proteins and the interaction with interstitial fibroblasts. Besides releasing pro-inflammatory cytokines and chemokines, the surviving epithelial cells and the underlying fibroblasts secrete factors contributing to airway repair, including the formation of the provisional extracellular matrix. This is indeed the substrate to which the epithelial cells at the edge of the lesion can attach to migrate in order to reconstitute the surface layer. In these processes airway epithelial cells receive the support of bronchial wall fibroblasts which actively release cytokines stimulating epithelial cell functions.

Total and allergen-specific IgE levels in serum reflect blood eosinophilia and fractional exhaled nitric oxide concentrations but not pulmonary functions in allergic asthmatic children sensitized to house dust mites.

Although elevated levels of serum immunoglobulin E (IgE) are considered the hallmark of atopic diseases, their clinical value in evaluating subjects with allergic disorders is under debate. To evaluate possible relationships between serum IgE levels and a variety of clinical parameters, 83 mild asthmatic children [10.98-year-old (2.95)], sensitized to house dust mites (HDM) Dermatophagoides pteronyssinus (Dp) or D. farinae (Df), were enrolled. As compared with normal control reference values detected in our laboratory, children with allergic asthma had higher blood eosinophil counts (expressed both as percentage and as absolute number) and higher fractional exhaled nitric oxide (FeNO) levels but similar values in pulmonary function parameters. In the allergic asthmatic population, serum levels of total, Dp-specific or Df-specific IgE correlated positively with eosinophil counts (Rho > or = 0.30, p < 0.01, each correlation) and FeNO levels (Rho > or = 0.33, p < 0.01, each correlation) but not with pulmonary function parameters (p > 0.1, each correlation). Finally, significant correlations, although moderate, were found in the allergic asthmatic population between eosinophil counts and FeNO levels (Rho > or = 0.42, p < 0.001, each correlation). Thus, in atopic children sensitized to HDM with mild intermittent asthma, IgE levels in blood appear to reflect systemic (blood eosinophils) and organ-specific (FeNO) markers of allergic inflammation but not pulmonary volumes or the degree of airflow limitation.

Modulation of the constitutive or cytokine-induced bronchial epithelial cell functions in vitro by fluticasone propionate.

When exposed to proinflammatory mediators, human bronchial epithelial cells (HBECs) upregulate the 'constitutive' adhesion molecule expression and cytokine/chemokine release. We tested whether and to what extent the inhibitory effect of fluticasone propionate on HBECs could involve the 'constitutive' and 'cytokine-induced' proinflammatory functions. Stimulation of the HBECs with interleukin (IL)-4 plus tumour necrosis factor (TNF)-alpha was more effective in upregulating intercellular adhesion molecule (ICAM)-1 ( approximately 2.2-fold increase) than vascular adhesion molecule (VCAM)-1 ( approximately 1.6-fold increase) expression (P<0.05) and in increasing the release of 'regulated on activation normal T cell expressed' (RANTES, 5.7-fold increase) than of IL-8 (3.5-fold increase) and granulocyte macrophage-colony stimulating factor (GM-CSF, 2.8-fold increase), (P<0.01). Fluticasone propionate, at the two concentrations tested (10 and 100 nM), was more effective in inhibiting the 'IL-4 plus TNF-alpha-induced' ICAM-1 expression than VCAM-1 expression (P<0.05) and in downregulating RANTES than IL-8 or GM-CSF secretion (P<0.05). The degree of inhibition demonstrated by fluticasone propionate appeared to be related to the degree of cell activation. In addition, for both adhesion molecules, the effect of fluticasone propionate at both concentrations tested appeared to be related to a complete inhibition of 'IL-4 plus TNF-alpha-induced' expression with no involvement of the 'constitutive' expression. Slightly different results were observed for cytokine/chemokine release. Indeed, evaluating RANTES, a complete inhibition of the 'IL-4 plus TNF-alpha-induced' release with a partial inhibition also of the 'constitutive' release at both concentrations of the drug tested was found, whereas for GM-CSF and IL-8, only a partial inhibition of the 'IL-4 plus TNF-alpha-induced' release in the presence of fluticasone propionate 10 and 100 nM. Thus, HBECs can constitutively or upon activation express adhesion molecules and secrete proinflammatory proteins at various levels and the different ability of fluticasone propionate to modulate the HBEC functions appears to be mostly related to the different inhibition of the various 'IL-4 plus TNF-alpha-induced' responses.

Correlations between exhaled nitric oxide levels, blood eosinophilia, and airway obstruction reversibility in childhood asthma are detectable only in atopic individuals.

The aim of this study was to compare in atopic and nonatopic asthmatic children correlations between two inflammation parameters, i.e., blood eosinophilia and exhaled nitric oxide (FE(NO)), and pulmonary function values, at baseline and after beta(2)-adrenergic bronchodilators. Ninety-two steroid-naive asthmatic children were evaluated: 26 were skin prick test- and RAST-negative (nonatopic subjects), whereas 66 were atopic, 15 being sensitized only to house dust mites (monosensitized) and 51 to mites and to at least one other class of allergens (polysensitized). Baseline spirometric values (FEV(1) and FEF(25-75%)) were similar in atopic and nonatopic groups (P > 0.1, each comparison). However, when compared to nonatopic subjects, atopic children showed a significantly higher degree of blood eosinophilia (3.0% and 6.7% white blood cell count, respectively; P = 0.0001) and higher FE(NO) levels (6.8 ppb and 16.0 ppb, respectively; P = 0.0001). While a positive correlation between FE(NO) levels and blood eosinophilia was observed in atopic children (r = 0.25, P = 0.041), no correlations between these two inflammation parameters and baseline pulmonary function values were demonstrated in any of the asthmatic groups. Inhalation of a beta(2)-agonist drug induced in the two asthmatic populations similar improvements in FEV(1) and FEF(25-75%) and no changes in FE(NO) levels or blood eosinophilia. However, only in atopic children positive correlations were found between percent variation in FEV(1) (delta%FEV(1)) and FE(NO) levels (r = 0.35, P = 0.006) or blood eosinophilia (r = 0.26, P = 0.04). Within the atopic group, no differences were found between mono- and polysensitized individuals in all parameters evaluated. Thus only in atopic children did parameters of inflammation correlate with airway obstruction reversibility.

Fibroblast-eosinophil interaction: modulation of adhesion molecules expression and chemokine release by human fetal lung fibroblasts in response to IL-4 and TNF-alpha.

In addition to be involved in airway remodelling observed in asthmatic patients, lung fibroblasts may directly contribute to pulmonary inflammation through the release of mediators and through the expression of surface molecules involved in cell-cell interaction. The aim of the study was to evaluate whether two cytokines involved in asthma pathogenesis, IL-4 and TNF-alpha, could modulate the expression of adhesion molecules (VCAM-1 and ICAM-1) and the secretion of chemokines (eotaxin and MCP-1) related to eosinophil recruitment and activation. The constitutive expression of VCAM-1 by unstimulated fibroblasts was over 2-fold lower than that of ICAM-1 (P<0.05). Significant differences were also observed in the release of chemokines by unstimulated fibroblast, the levels of eotaxin being over 17-fold lower than those of MCP-1. Stimulation of the cells with IL-4 or TNF-alpha induced a dose-dependent increase in VCAM-1, while ICAM-1 was overexpressed only in culture stimulated by TNF-alpha (P<0.05) but not in those exposed to IL-4 (P>0.05 each comparison). In contrast, a significant increase in MCP-1 and eotaxin release was observed in the presence of TNF-alpha (P<0.05) but not of IL-4 (P>0.05). These data show that two 'proinflammatory' cytokines, such as IL-4 and TNF-alpha, may have different and complementary effects on functions involved in the cross-talking between fibroblasts and eosinophils.