In asthma, the acute increment of airway responsiveness caused by exposure to allergen is associated with influx of eosinophils into the airways. The relationship between chronic airway hyperresponsiveness and airway inflammation is unclear, as they do not change consistently following long-term anti-inflammatory treatments. We studied 71 patients with chronic asthma and allergic sensitization to perennial allergens. Airway responsiveness was determined by inhalation of methacholine, and airway inflammation was quantified by induced sputum (n = 28) or bronchoalveolar lavage (n = 43) and bronchial biopsy (n = 20). The relationships between airway responsiveness and the numbers of different inflammatory cells were assessed by multiple regression analysis. No significant correlations were found between the degree of airway responsiveness and the numbers of inflammatory cells in sputum or bronchoalveolar lavage or bronchial biopsy. By contrast, baseline lung function was inversely related to the numbers of eosinophils and directly related to the numbers of macrophages. The eosinophil cationic protein contents of either sputum or bronchoalveolar lavage were significantly correlated with the percentages of eosinophils but not with airway responsiveness. We suggest that other factors (e.g., airway wall remodeling or autonomic dysfunction) may be responsible for most of the interindividual variability of airway responsiveness in asthma.

Acute bronchiolitis is the leading cause of lower respiratory tract infection and hospitalization in children less than 1 year of age worldwide. It is usually a mild disease, but some children may develop severe symptoms, requiring hospital admission and ventilatory support in the ICU. Infants with pre-existing risk factors (prematurity, bronchopulmonary dysplasia, congenital heart diseases and immunodeficiency) may be predisposed to a severe form of the disease.Clinical diagnosis of bronchiolitis is manly based on medical history and physical examination (rhinorrhea, cough, crackles, wheezing and signs of respiratory distress). Etiological diagnosis, with antigen or genome detection to identify viruses involved, may have a role in reducing hospital transmission of the infection.Criteria for hospitalization include low oxygen saturation (<90-92%), moderate-to-severe respiratory distress, dehydration and presence of apnea. Children with pre-existing risk factors should be carefully assessed.To date, there is no specific treatment for viral bronchiolitis, and the mainstay of therapy is supportive care. This consists of nasal suctioning and nebulized 3% hypertonic saline, assisted feeding and hydration, humidified O2 delivery. The possible role of any pharmacological approach is still debated, and till now there is no evidence to support the use of bronchodilators, corticosteroids, chest physiotherapy, antibiotics or antivirals. Nebulized adrenaline may be sometimes useful in the emergency room. Nebulized adrenaline can be useful in the hospital setting for treatment as needed. Lacking a specific etiological treatment, prophylaxis and prevention, especially in children at high risk of severe infection, have a fundamental role. Environmental preventive measures minimize viral transmission in hospital, in the outpatient setting and at home. Pharmacological prophylaxis with palivizumab for RSV bronchiolitis is indicated in specific categories of children at risk during the epidemic period.Viral bronchiolitis, especially in the case of severe form, may correlate with an increased incidence of recurrent wheezing in pre-schooled children and with asthma at school age.The aim of this document is to provide a multidisciplinary update on the current recommendations for the management and prevention of bronchiolitis, in order to share useful indications, identify gaps in knowledge and drive future research.

Mesenchymal stem cells (MSCs) are multipotent cells able to differentiate along different pathways including chondrogenic, osteogenic and adipogenic lineages. MSCs with a fibroblast-like morphology have been identified in human fetal lung. However, their frequency and characterization in human adult lung have not been yet evaluated. Therefore, we analyzed the mesenchymal phenotype and differentiation ability of cultured human adult bronchial fibroblast-like cells (Br) in comparison with those of mesenchymal cell progenitors isolated from fetal lung (ICIG7) and adult bone marrow (BM212) tissues. Surface immunophenotyping by flow cytometry revealed a similar expression pattern of antigens characteristic of marrow-derived MSCs, including CD34 (-), CD45 (-), CD90/Thy-1 (+), CD73/SH3, SH4 (+), CD105/SH2 (+) and CD166/ALCAM (+) in Br, ICIG7 and BM212 cells. There was one exception, STRO-1 antigen, which was only weakly expressed in Br cells. Analysis of cytoskeleton and matrix composition by immunostaining showed that lung and marrow-derived cells homogeneously expressed vimentin and nestin proteins in intermediate filaments while they were all devoid of epithelial cytokeratins. Additionally, alpha-smooth muscle actin was also present in microfilaments of a low number of cells. All cell types predominantly produced collagen and fibronectin extracellular matrix as evidenced by staining with the monoclonal antibodies to collagen prolyl 4-hydroxylase and fibronectin isoforms containing the extradomain (ED)-A together with ED-B in ICIG7 cells. Br cells similarly to fetal lung and marrow fibroblasts were able to differentiate along the three adipogenic, osteogenic and chondrogenic mesenchymal pathways when cultured under appropriate inducible conditions. Altogether, these data indicate that MSCs are present in human adult lung. They may be actively involved in lung tissue repair under physiological and pathological circumstances.

There is evidence that respiratory viruses play a key role in the development and exacerbation of obstructive respiratory diseases in children. This review attempts to juxtapose the separate profiles and prototypes of pathogenenetic mechanisms represented by the two most common amongst such viruses: respiratory syncytial virus (RSV) and human rhinovirus (HRV).RSV represents the most common agent of severe airway disease in infants and young children, and is predominant in winter months. Large epidemiological studies have revealed an unequivocal relationship between RSV infection and subsequent wheezing into childhood, thought to be related to long-term changes in neuroimmune control of the airways rather than allergic sensitisation.HRV is a highly diverse group of viruses that affect subjects of all ages, is ubiquitous and occurs yearround. In contrast to RSV, infections with HRV cause minimal cytotoxicity but induce a rapid production of cytokines and chemokines with amplification of the inflammatory response. The susceptibility to HRVinduced bronchiolitis and subsequent wheezing appears to be linked to individual predisposition since it is often associated with a family or personal history of asthma/atopy.Thus, RSV probably serves as an "inducer" rather than a "trigger". Conversely, HRVs seem to serve as a "trigger" rather than an "inducer" in predisposed individuals. @ERSpublications Comprehensive overview of the different roles of RSV and HRV in the pathogenesis of recurrent wheezing in childhood

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.