Having a pet dog may lower the risk of eczema in children who are genetically prone to the condition, shedding light on how environmental factors may influence genetic risks
New research published in Allergy indicates that specific environmental exposures, such as having a pet dog, may influence the risk of genetic eczema in children, a condition characterised by dry, itchy, and inflamed skin.
The international study team, led by scientists from the Universities of Edinburgh and Bristol, the London School of Hygiene & Tropical Medicine, and Helmholtz Munich, examined data from nearly 300,000 people to investigate whether those prone to developing eczema might respond differently to environmental factors.
Analysing 18 early-life environmental factors and 24 eczema genetic variants
For the study, the researchers examined data from 16 European studies to test for interactions between the 24 most significant eczema-associated genetic variants and 18 early-life environmental factors. They applied their findings to an additional ten studies and used lab modelling tests to assess their results.
The first analysis included 25,339 individuals and revealed evidence of interaction between seven environmental factors (antibiotic use, cat ownership, dog ownership, breastfeeding, elder sibling, smoking, and washing practices) and at least one established genetic variant for eczema, resulting in a total of 14 interactions.
In a further analysis of 254,532 individuals, dog exposure interacted with a specific genetic risk variant on chromosome 5, near the gene that encodes the interleukin-7 receptor, a protein involved in immune cell function. In lab modelling tests, a scientific process where researchers simulate real-world conditions in a controlled environment, this variant affects the expression of interleukin-7 receptors in human skin cells. Dog exposure modifies the genetic effect of this variant on the development of eczema, essentially providing a protective effect by suppressing skin inflammation.
“Our research aims to answer some of the most difficult questions that I am asked in the clinic: ‘Why does my child have eczema?’ and ‘What can I do to help protect my baby?’ We know that genetic makeup affects a child’s risk of developing eczema and previous studies have shown that owning a pet dog may be protective, but this is the first study to show how this may occur at a molecular level,” said corresponding author Sara J. Brown, MD, PhD, FRCPE, of the University of Edinburgh. “More work is needed, but our findings mean we have a chance to intervene in the rise of allergic disease to protect future generations.”
Dr Marie Standl, from Helmholtz Munich, said, “This study sheds light on why some children develop eczema in response to environmental exposures while others don’t. Not every preventive measure works for everyone – and that’s precisely why gene-environment studies are crucial. They help us move toward more personalised, effective prevention strategies.”
The researchers found similar effects in younger children with older siblings
The study showed a similar effect among both young children and older children; however, further studies are needed to confirm this link. The researchers also suggested that exposure to a variety of bacteria at an early age, through contact with dogs and other children, could be behind the protective effect.
Moreover, the study populations were limited to those of a white European background. Research involving a more diverse group of people is needed to understand better interactions between genetic and environmental factors linked to eczema in other ancestral groups, the team commented.
