Bronchiolitis

How Does Bronchiolitis Lead To Asthma? 

Respiratory Syncytial Virus (RSV)

How Does Bronchiolitis Lead To Asthma?
First Published: Investigator - February 2007
Updated:

How does infant Bronchiolitis caused by the Respiratory Syncytial Virus (RSV) lead to the development of asthma and persistent wheezing? Scientists at Flinders Medical Centre are attempting to unlock the answer to this question which has been of interest to researchers around the world for many years.

RSV Bronchiolitis is a very common illness usually contracted by infants during their first two years. It exhibits common cold like symptoms such as shortness of breath and coughing and in many infant cases the severity is such that hospitalisation is required.

Currently there is no specific treatment or vaccine for RSV Bronchiolitis. Those who develop this disease are generally cared for in a supportive manner similar to the treatment of a severe cold or flu with rest and oxygen supply if blood-oxygen levels drop too low.

“The natural course of this virus is normally only a week or two,” said Dr Dani-Louise Bryan, from the department of Critical Care Medicine. “However, there is a significant chance that children who contract RSV Bronchiolitis will go on to develop asthma or persistent wheezing.”

In past research Dr Bryan found an increase of a hormone like substance called prostaglandin (PGE2), which is triggered by the immune system to defend lung cells that have been exposed to the RSV virus by causing inflammation within the lung.

However, Dr Bryan has found that this defensive action can go too far, leading to the damage of healthy tissues and cells that aren’t infected. It is thought that this damage of healthy lung cells, to try and clear the virus, could be what leads to the development of asthma and persistent wheeze later in life.

“If the lungs are damaged when the patient is very young it seems that there is a predisposition to hyper-responsive lungs, causing breathing difficulties throughout their lives” said Dr Bryan. “With further investigation of PGE2 our team at Flinders hopes to pin point at what point this inflammatory response to RSV should be stopped.”

This research could lead to the development of a therapeutic agent that can modify the body’s responses to RSV where necessary and reduce healthy lung tissue damage.

Respiratory Syncytial Virus (RSV)
First Published: Investigator - April 2003
Updated:

Respiratory Syncytial Virus (RSV) is the most common and dangerous virus in infants, effecting almost 100% of babies worldwide.

RSV lives inside the cells lining in the respiratory system, causing swelling coupled with the production of large amounts of mucus.

Almost half of those infants affected by RSV will develop a severe chest infection commonly known as Bronchiolitis.

Bronchiolitis causes inflammation of the airways. It is not known what causes the inflammation. Without an understanding of this inflammation and how it occurs, it is not possible to develop effective treatments.

Professor Kevin Forsyth and his team in the Department of Paediatrics and Child Health at the Flinders Medical Centre have been investigating the mechanism of the disease process of RSV Bronchiolitis through a technique called Microarray Analysis, in an effort to create effective therapies.

Professor Forsyth explains, "When RSV infects the lungs, many cells release an array of substances known as cytokines. The Microarray Analysis allows the researchers to understand the response of thousands of genes expressed by these cells. Microarray analysis enable us to measure the response of thousands of genes which might be producing this lung inflammation. We are identifying which genes appear to be important in bronchiolitis. This will give us valuable clues in our search for understanding of the lung inflammation in bronchiolitis."

"The results obtained will lead us to identify several key substances important in the disease development of Bronchiolitis. If we can understand what happens then we can devise effective treatments. We are looking for a footprint if you like, to show us which genes are being switched on in this condition", said Professor Forsyth.

He added, "To date, our understanding on the range of these substances produced during acute bronchiolitis in children is limited. Lack of progress may have been caused by the difficulties in obtaining clinical material from babies and the lack of expertise and techniques. We now have access to fresh clinical material."

It is believed prevention of RSV bronchiolitis in babies will reduce the prevalence of childhood asthma in industrialised countries by 80%. With virtually 100% of newborn babies infected with RSV, this is welcome news.