Early contact with PET dogs protects genetically susceptible children from eczema

The study suggests that having a dog at home can help prevent eczema in children who are genetically susceptible to this condition.

Scientists say that children with a DNA change that increases their chance of developing eczema were less likely if they were exposed to a dog in an early period of life.

Discoveries provide new information about what can cause eczema in children and how environmental factors can affect genetic risk, experts say.

In the study, it did not apply to the impact of exposure to the dog in the treatment of existing eczema, and experts warn that the introduction of a dog may worsen the symptoms of some children.

Eczema is an itchy skin disorder caused by a combination of genetic and environmental effects, but little is known about how both they interact.

The International Research Team, led by scientists from the universities in Edinburgh and Bristol, London School of Hygiene & Tropical Medicine and Helmholtz Munich, examined data from almost 300,000 people to examine whether people willing to develop eczema may respond differently to environmental factors.

Scientists tested interactions between the 24 most important genetic variants related to eczema and 18 environmental factors of early life during the mother’s pregnancy and the first year of life of the child.

Initial analysis of over 25,000 people suggested that there may be a relationship between seven environmental factors – ownership of dogs, older siblings, ownership of a cat, breastfeeding, smoking, practices related to antibiotics and washing practices – and at least one determined genetic variant of eczema.

Then they tried to repeat their discoveries in a larger group of almost 255,000 people. The strongest confirmed interaction concerned the region of the DNA Code, which increased the risk of eczema, but in children or children whose families had a dog for pets, the risk disappeared.

The variability of the genetic code was located near the Interleukin-7 receptor gene (IL-7R)-a white involved in the function of immune cells and inflammation.

Laboratory tests have confirmed that in human skin cells with genetic variant, molecular signals from a dog that can cause an allergy instead of suppressing dermatitis.

Discoveries suggest that the IL-7R protein can be a potential goal in future treatment or eczema prevention, experts say.

The study also indicated a similar influence among young children with older siblings, but further research is needed to confirm the link. Scientists suggest that exposure to various bacteria at a young age, through contact with dogs and other children, may be in favor of a protective effect.

The populations used in the study were limited to the population of white European origin. You need research on a more diverse group of people to better understand the interactions between genetic and environmental factors related to eczema in other groups of ancestors.

The study was published in the journal: https://onlinelibary.wiley.com/doi/10.1111/all.16605 [URL will become active after embargo lifts]. The international research team included scientists from Great Britain, Germany, Denmark, the Netherlands, Norway, Spain, the United States, Ireland, France, Sweden, Australia, Italy and Kuwait.

The most difficult questions asked by parents in the clinic concern why their child has eczema and how they can help. We know that genetic makeup affects the risk of developing eczema, and earlier studies have shown that having a PET dog can be protective, but this is the first study that showed how this may occur at the molecular level. More work is needed, but our discoveries mean that we have a chance to intervene in an allergic disease to protect future generations. “

Professor Sara Brown, University of Edinburgh’s Institute of Genetics and Cancer

Dr. Marie Standl from Helmholtz Munich said: “This study sheds light on why some children develop eczema in response to environmental exhibitions, while others do not. Not every preventive measure works for everyone – and that’s why genes and environment research is key. They help us go to more personalized, effective prevention strategies.”