Touching Lives - June 2004
Important advance in battle against bronchiolitis
Most cases of this severe lung disease are caused by infection with a highly contagious virus called respiratory syncytial virus (RSV). All children are likely to get infected with RSV, and most suffer only mild cough or cold-like symptoms.
However, in some cases, RSV infection causes severe lung inflammation which can result in life-threatening breathing difficulties. Some babies are more susceptible to bronchiolitis, including those born prematurely or with an underlying medical condition such as a heart defect. However, healthy babies can also develop the condition and the reasons for the diverse reactions to the virus are not understood.
With funding of over £140,000 from Action Medical Research, a team of researchers has carried out vital work which gives valuable insight into how babies’ lungs respond to RSV infection. Rosalind Smyth, who is Professor of Paediatric Medicine at Liverpool’s Alder Hey Hospital and internationally renowned in her field, headed the three-year project.
The study involved measuring cell and protein concentrations in lung fluid taken during normal nursing care from infants with RSV bronchiolitis. Such measurements help us understand more about how the body’s immune system is responding to the virus and the causes of the symptoms suffered by children with severe bronchiolitis.
The team discovered that ^the number of cells in the airways of babies with RSV infection who were born full-term is much greater than in infants born prematurely^, suggesting that different disease processes are involved.
The team also found that a protein known as Interleukin-9 (IL-9) is produced in very large amounts by immune cells called neutrophils in these infants’ airways. This protein is more commonly seen in the lungs of asthmatics and causes mucus production. In fact, many of the respiratory symptoms seen in children with bronchiolitis are caused by mucus overproduction.
Recently, a new virus called human metapneumovirus has been found to cause bronchiolitis. The Liverpool team discovered that most infants with severe RSV bronchiolitis are also infected with human metapneumovirus. This may be a significant discovery as it could help to explain why some infants develop severe bronchiolitis while others have only trivial symptoms.
These important findings help us to understand how RSV causes disease, which takes us a step closer to developing new treatments and an RSV vaccine.
Professor Smyth told Touching Lives, “At the moment we have no specific treatment to help these very vulnerable infants when they become seriously ill. These discoveries have provided important new information about the disease processes, which we hope will lead to new treatments for bronchiolitis.”