The way a baby’s immune system works seems to influence whether they will develop temporary or persistent asthma later in life. The finding could help identify more targeted treatments for different types of asthma, say researchers behind the work.
By the time a child is 18 months old, they have already been exposed to plenty of bacteria, viruses and fungi. These early encounters with pathogens start to shape a child’s immune system for later life.
To find out if such experiences might also predict a child’s risk of developing disease, Susanne Brix at the Technical University of Denmark in Kongens Lyngby and her colleagues followed a group of infants in Denmark for the first six years of their lives.
The team looked at how immune cells work in toddlers, and whether this is linked to the children’s risk of developing asthma by the time they were six years old. “Asthma is pretty prevalent in the Nordic European countries,” says Brix. “We have a prevalence of around 20 per cent in early childhood.”
Brix and her colleagues first took blood samples from 541 18-month-olds. Each blood sample was then presented with a range of compounds – such as fragments of viruses or components of vaccines – to see how the immune cells in the blood would respond.
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The responses of a particular type of immune cell seem to be linked to a child’s later risk of asthma, says Brix. This cell type, called a T helper cell, responds to potentially harmful pathogens by releasing a range of proteins.
The way these cells release two specific proteins seems to be linked to whether the child will later develop asthma or not – babies whose immune cells produce more of these proteins are significantly more likely to have asthma when they are six years old, says Brix.
Her team also found differences between girls and boys. The immune cells in blood samples taken from boys responded more strongly to bacteria and fungi, while girls seem to mount stronger responses to viruses.
Brix doesn’t know why this might be the case, but she suspects sex hormones like testosterone may be influencing the immune system. The difference may explain why boys are more likely to develop asthma early in life, says Brix.
It will be difficult to create a test that would be able to predict which babies will go on to develop asthma, but Brix says she hopes that her research might help to identify the best treatments for different types of asthma.
Some cases of asthma are temporary, and resolve in childhood, while others are persistent. The transient type is more common in boys, says Brix. It may be that one type of asthma is linked to the immune system’s response to viruses, while another is linked to the response to bacteria. Better targeted treatments could potentially be developed to treat each type, she says.
Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.aaw0258
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