Asthma Cause Discovery Could Help In Prevention, Treatment Of The Lung Disease
A team of American researchers has discovered a major cause of asthma that could lead to effective prevention and treatment of the disease.
According to their recent report in the journal Nature Medicine, the team of immunologists and pediatricians found that a viral infection in newborns leads to the impairment of regulatory aspects of the immune system, increasing the risk of asthma later in life.
In their experiment, researchers repeatedly exposed infant mice to respiratory syncytial virus (RSV) through their mother's milk. The disease eventually stripped the mice's immune cells of their regulatory ability to stop inflammation in its lung's passages after being exposed to a pathogen or irritant.
When an irritant enters the airways of a person with asthma, the immune system reacts to it as if it were a pathogen, causing the airways to become inflamed and produce mucus that makes breathing difficult. This study illustrates that early exposure to RSV makes it hard for the body to tolerate the response of its own immune system, making it susceptible to asthma.
Previous research has shown a connection between repeated lung exposures to RSV and developing asthma later in life. A 2010 study by Swedish scientists showed that 39 percent of infants taken to hospital with RSV had asthma when they were 18. They also noted that 9 percent of their control group developed asthma without contracting RSV.
The latest study, which was led by researchers at the University of Pittsburgh's School of Medicine, expands on that research by providing evidence for a mechanism that drives the drop in immune tolerance.
Their experiments showed that the virus suppressed regulatory T cells. According to the report, repeated exposure to RSV led to a "complete loss of suppressive function" of the regulatory T cells. This ultimately led to the mice developing asthma-like symptoms.
Researchers said the results of their study pointed to a period in early development when the immune system's regulatory cells were vulnerable to being "crippled". They added that this knowledge could lead to new treatments and prevention measures.
"This research provides vital information on how viruses interact with our immune cells and why this might lead to an increased risk of asthma," said Malayka Rahman, from Asthma UK. "What's really exciting is the potential of these findings to translate into new treatments for asthma in the future."
The University of Pittsburgh study comes on the heels of a British study published earlier this month that showed boosting asthmatics' immune systems can help reduce the number of asthma attacks due to viral infection.
According to the results of that report, the treatment could prevent up to 80 percent of infections that trigger asthma attacks.
"We have demonstrated the potential of a treatment, simply breathed in by the patient, which significantly reduces worsening of asthma symptoms and the patient's need to use their asthma inhaler in response to common cold infection," said lead author Ratko Djukanovic, a respiratory specialist at the University of Southampton. "By presenting an immune system protein molecule, interferon beta, to the patient's lungs we can prime their body to challenge infections more effectively."