New Delhi, June 4 Early exposure to pet dogs may lower the risk of developing atopic eczema -- a condition characterised by dry, itchy, and inflamed skin -- among children who are genetically prone to the condition.
Eczema is an itchy skin disorder caused by a combination of genetic and environmental effects, but little is known about how the two interact.
The findings provide new insights into what could cause eczema in children and how environmental factors may influence genetic risk, experts say.
The study did not look at the effect of dog exposure in the treatment of existing eczema, and experts caution that introducing a dog may make symptoms worse in some children.
“We know that genetic make-up 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 Sara J. Brown, from 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,” she added.
For the research published in Allergy, the team analysed 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 10 studies and used lab modelling tests to assess their results.
The first analysis (including 25,339 individuals) showed suggestive evidence for 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, with 14 interactions in total.
In the additional analysis (254,532 individuals), dog exposure interacted with a particular genetic risk variant on chromosome 5, near the gene that codes for the interleukin-7 receptor, a protein involved in immune cell function.
Lab modelling tests showed that this variant affects the expression of interleukin-7 receptors in human skin cells and that dog exposure modifies the genetic effect of this variant on the development of eczema, essentially providing a protective effect by suppressing skin inflammation.
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