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Paediatric Pulmonology and Allergology
2008 April, Vol. XI, No. 1 (3748-3755)
THE ROLE OF INFECTIONS IN THE INDUCTION OF ASTHMA: GENETIC AND INFLAMMATORY DRIVERS
Andrew Bush
Royal Brompton Hospital, Imperial College, London, UK
The article is devoted to current data of interaction between viral infections, genes and chronic inflammation in the development of paediatric asthma. It was described the role of genes in fetal lung development, in particular branching morphogenesis, and later in the development of airway calibres. Antenatal maternal factors, maternal smoking, atopy, maternal hypertension, diabetes, used medications has also been associated with impaired lung function in the newborn. One factor predisposing to virus induced symptoms in the first years of life is an antenatal reduction in airway calibre. There is evidence that early exposure to viral infection may protect against later asthma. Early placement of a first child in a crêche is associated with more frequent wheeze in early life, but less asthma at age six years. Taken together, the balance of the epidemiological evidence, together with these scientific studies, suggest that RSV bronchiolitis is seen in the setting of the child primed by genetic factors and antenatal exposures; that it is these prior exposures which may predispose to asthma. RSV itself does not lead to asthma in an ‘unprimed’ child. Focus in this presentation are viruses, because there are insufficient data on any putative role of Chlamydia and Mycoplasma causing asthma in the preschool years.