Michela Silvestri

High serum levels of tumour necrosis factor‐α and interleukin‐8 in severe asthma: markers of systemic inflammation?

Background Severe asthma is characterized by elevated levels of pro‐inflammatory cytokines and neutrophilic inflammation in the airways. Blood cytokines, markers of ‘systemic’ inflammation, may be a feature of amplified inflammation in severe asthma.

Cysteinyl leukotrienes induce human eosinophil locomotion and adhesion molecule expression via a CysLT1 receptor-mediated mechanism

Background The mechanisms involved in eosinophil recruitment by cysteinyl‐leukotrienes (CysLTs) remain to be defined.

Epidemiology and clinical features of Mycoplasma pneumoniae infection in children

Mycoplasma pneumoniae (MP) is, considered to affect rarely children less than 5 yrs of age. This study was performed to describe the epidemiology and the clinical features of MP lower respiratory tract infection (LRTI) in children, presenting to a tertiary children hospital. Eleven month-longitudinal study of LRTI due to MP, diagnosed by polymerase chain reaction (PCR) on throat swab specimen, was performed. Out of 866 children with LRTI admitted to the Gaslini Pediatric Institute in Genoa, 102 had a positive PCR for MP. We found 39 preschool-aged children, 42 school-aged children and 21 young adolescent [6.20 (3.81) yrs old]. Interestingly, eight MP+ infants had <8 months of age. The commonest presentations were cough and/or fever (76.5%). Tachypnoea, upper respiratory tract involvement, diarrhoea and vomiting were more common in the <5 yr Gr as compared to the other groups. Chest X-ray was found abnormal in 76 children: consolidations were the commonest finding. Laboratory test showed that the preschool-aged children had a higher number of lymphocytes (p<0.0001) and monocytes (p=0.009). Thrombocytosis was found in 35.7% of children and was more frequent in the preschool-aged children (p=0.013). MP infection is common in preschool-aged children, including young infants, and may have different clinical presentation, as compared to older children.

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.

Dissociation between exhaled nitric oxide and hyperresponsiveness in children with mild intermittent asthma

BACKGROUND Bronchial hyperresponsiveness and airway inflammation are distinctive features of asthma. Evaluation of nitric oxide (NO) levels in expired air have been proposed as a reliable method for assessing the airway inflammatory events in asthmatic subjects. A study was undertaken to evaluate whether airway hyperresponsiveness is related to levels of exhaled NO. METHODS Thirty two steroid-naive atopic children with mild intermittent asthma of mean (SD) age 11.8 (2.3) years and 28 age matched healthy controls were studied to investigate whether baseline lung function or airway hyperresponsiveness is related to levels of exhaled NO. Airway responsiveness was assessed as the dose of methacholine causing a 20% decrease in forced expiratory volume in one second (FEV1) from control (PD20 methacholine) and exhaled NO levels were measured by chemiluminescence analysis of exhaled air. RESULTS At baseline asthmatic children had significantly higher NO levels than controls (mean difference 25.87 ppb (95% CI 18.91 to 32.83); p<0.0001) but there were no significant differences in lung function parameters (forced vital capacity (FVC), FEV1 (% pred), and forced expiratory flows at 25–75% of vital capacity (FEF25–75%)). In the asthmatic group exhaled NO levels were not significantly correlated with baseline lung function values or PD20 methacholine. CONCLUSIONS These results suggest that levels of exhaled NO are not accurate predictors of the degree of airway responsiveness to inhaled methacholine in children with mild intermittent asthma.

Airway eosinophilic inflammation, epithelial damage, and bronchial hyperresponsiveness in patients with mild-moderate, stable asthma

Allergic asthma is characterized by chronic recruitment of eosinophils in the airways. Once activated, eosinophils release toxic products, including eosinophil cationic protein (ECP), able to damage airway epithelial cells. To test the hypothesis that also in mild‐moderate stable asthma, a significant eosinophil activation could occur, we studied 25 asthmatic patients (34 ± 19 years old), of whom 18 were allergic (27 ± 12 years) and seven nonallergic (42±10 years), with FEV1 values ±70% of predicted, and eight normal volunteers (controls, 33 ±11 years). All subjects underwent methacholine (MCh) challenge on the first visit, and bronchoalveolar lavage (BAL) on the second visit (approximately 3–4 days later). BAL cells were counted and albumin (Alb) (as index of protein dilution in BAL fluid) and ECP levels (as index of eosinophil activation) in BAL fluid were measured. As compared to controls, a significant increase in BAL eosinophil and in BAL epithelial cell numbers was observed in asthmatic patients (P>0.05, each comparison), with no differences between the two asthmatic patient subgroups. Detectable ECP levels (>2 μg/1) were found in BAL of 18 asthmatic patients (14 allergic and four nonallergic asthmatic patients), while Alb levels were measurable in 25 BAL fluids and found to be similar in controls and asthmatic patients, and in the two asthmatic patient subgroups (P>0.05, each comparison). In BAL of asthmatic patients, positive correlations were found between eosinophil numbers and 1) ECP/Alb levels (r= 0.50, P = 0.020); 2) epithelial cell numbers (r = 0.S0, P = 0.014). In asthmatic patients, a significant negative correlation was found between bronchial reactivity to MCh (log Pd15) and ECP/Alb levels in BAL fluid (r=‐0.6, P= 0.005), whereas no correlation was found between log Pd15 MCh and BAL eosinophil or epithelial cell number (P>0.1, each correlation). These data suggest that bronchial eosinophil recruitment and activation may occur also in mild‐moderate stable asthma and that bronchial epithelium damage and airway responsiveness may be partially associated with the eosinophilic inflammatory reaction.

Bronchoalveolar lavage and esophageal pH monitoring data in children with "difficult to treat" respiratory symptoms.

Gastroesophageal reflux (GER) may be associated with chronic or recurrent asthma‐like symptoms secondary to bronchoconstrictor reflexes and/or inhalation of gastric content. The presence of lipid‐laden alveolar macrophages has been proposed as an index to establish the degree of gastric aspiration. We evaluated 20 children with “difficult to treat” respiratory symptoms and a clinical history suggestive of GER. All children underwent 24‐hr esophageal pH monitoring (pHm) and fiberoptic bronchoscopy with bronchoalveolar lavage (BAL). The amount of lipid per single macrophage was determined by a semiquantitative method, using fluorescence microscopy to detect Nile‐Red‐stained BAL cells and calculating a lipid‐laden macrophage index (LLMI).

Fluticasone and salmeterol downregulate in vitro, fibroblast proliferation and ICAM-1 or H-CAM expression

Beta2-adrenoreceptor agonists have pharmacological properties that may suggest an inhibitory effect on various aspects of the inflammatory and repair processes that characterize asthma. Since fibroblasts express beta2-adrenoreceptors, the effects of different concentrations (0.1-100 nM) of fluticasone propionate (FP), salmeterol (S) and their combination (FP+S) on lung fibroblast proliferation and adhesion molecule expression were evaluated. Stimulation of human foetal lung fibroblasts with a fibrogenic cytokine, basic fibroblast growth factor (bFGF), resulted in a [methyl-3H] thymidine ([3H]TdR) uptake, four-fold higher than that of control cultures (p=0.0001) and was significantly inhibited by S, at all the concentrations tested (0.1-100 nM; p<0.05). No changes in bFGF-induced cell proliferation were observed in the presence of FP (0.1-100 nM; p>0.05, all comparisons). In addition, the association FP+S did not improve the inhibitory activity of S alone (p>0.05, each comparison). An upregulation of intercellular adhesion molecule-1 (ICAM-1) expression was induced by tumour necrosis factor-alpha (TNF-alpha) (p=0.0004), but not by interleukin-4 (IL-4) (p>0.05), while none of the two cytokines were able to increase hyaluronic-cellular adhesion molecule (H-CAM) expression by lung fibroblasts (p>0.05). A significant downregulation of ICAM-1 or H-CAM expression was demonstrated in the presence of FP or S, at all concentrations tested (0.1-100 nM; p<0.01, each comparison). Interestingly, S (10 nM and 100 nM) was able to enhance the inhibitory activity of FP on ICAM-1 expression (p<0.01), but not on H-CAM expression (p>0.1). These results show that in human foetal lung fibroblasts, fluticasone propionate and salmeterol are effective in modulating in vitro, different lung fibroblast biological functions that are likely to be involved in airway remodelling.

Exhaled nitric oxide levels in non-allergic and allergic mono- or polysensitised children with asthma

BACKGROUND Increased fractional exhaled NO concentrations (Feno) and blood/tissue eosinophilia are frequently reported in allergic children with mild asthma and are thought to reflect the intensity of the inflammation characterising the disease. The aim of this study was to investigate possible differences in Feno levels or in the intensity of the blood eosinophilia in allergic and non-allergic asthmatic children. METHODS 112 children with stable, mild, intermittent asthma with a positive bronchial challenge to methacholine were consecutively enrolled in the study; 56 were skin prick test and RAST negative (non-sensitised) while 56 were sensitised to house dust mites (23 only to house dust mites (monosensitised) and 33 were sensitised to mites and at least another class of allergens (pollens, pet danders, or moulds)). Nineteen sex and age matched healthy children formed a control group. RESULTS Compared with non-allergic patients, allergic children had a significantly higher rate of blood eosinophilia (p=0.0001) with no differences between mono- and polysensitised individuals. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), forced expiratory flow at 25–75% of vital capacity (FEF25–75%), and the degree of bronchial reactivity to methacholine were similar in non-atopic and atopic children, with no differences between mono- and polysensitised individuals. Feno levels measured by chemiluminescence analyser were higher in asthmatic children (15.9 (14.3) ppb) than in the control group (7.6 (1.6) ppb, p=0.04) and higher in allergic patients (23.9 (2.1) ppb) than in non-allergic patients (7.9 (0.8) ppb, p=0.0001), but there were no differences between mono- and polysensitised individuals (p>0.1). Significant correlations between blood eosinophilia and Feno levels were seen only in allergic (r=0.35, p<0.01) and in polysensitised individuals (r=0.45, p<0.05). CONCLUSIONS In children with mild asthma, a similar degree of functional disease severity may be associated with a higher inflammatory component in allergic than in non-allergic subjects.

Smoke exposure, wheezing, and asthma development: A systematic review and meta‐analysis in unselected birth cohorts

The understanding of the role of smoking exposure in the induction of wheezing and asthma in children is important for prevention.