How allergies may get under our skin

Why do some children develop allergies while others sail through childhood without ever having an itch or a wheezy breath?

This is a mystery that has bedevilled doctors and researchers for decades. Now, at long last, we may have some answers, and possibly some means to prevent children from developing these conditions in the future.

And it is all about looking after our skin.

Allergies in children are incredibly common and are a major burden for children, their families and the health system.

In our HealthNuts study of one-year old children, we found that one in every 10 had an allergy to a food. In addition, about one in three children from Melbourne will develop eczema, while one in five will develop asthma.

Behind each of these numbers is a child not able to eat freely at a birthday party for risk of a serious reaction to a food allergen; or a child struggling to concentrate and sleep due to their eczema itching; or a child not able to keep up with their friends because they are short of breath.

While many kids grow of those conditions over time, they also commonly reoccur in later life or develop into hay fever, making them life-long issues.

So why has there been an increase in allergies?

There are lots of suggested explanations, but there are few that are consistently supported by scientific research. Genetics is certainly important, and if you come from a family with allergies you are more likely to develop allergies.

However, changes in the genetic profiles of our populations alone cannot explain the rapid increases in allergic disease that we have seen – the rise in allergies that we have seen over the last 50 to 60 years has happened too quickly for this to be the case.

For example, admissions to hospital because of severe allergic reactions have doubled over the last decade in Australia, the US and the UK. In Australia, admissions for severe reactions due to food allergies among children aged up to four years have increased even more.

The emerging evidence is that allergies may start with “leaky” skin, that is skin that does not act as an effective barrier .

Our skin is our largest organ and has an important role to act as a barrier to the external world, keeping out bugs (viruses and bacteria), toxins and environmental allergens. It is well established that kids who develop eczema are at increased risk of developing food allergies and asthma, particularly if it is severe and starts in the first six months of life.

What is less clear is why this is the case. Is it because the same genetic variants, or the same things in the environment, cause children to develop both eczema and food allergy? Or could eczema and the associated damage to the skin barrier actually cause food allergy?

There is growing evidence that the damage caused by eczema to the skin may impair its ability to be an effective barrier against the environment, including allergens.

Animal studies have shown that applying food allergens to damaged skin is a powerful way of inducing allergic reactions.

A leading theory for why children develop allergies is that a range of factors (both genetic and environmental) can damage the skin barrier, causing the body to react to an allergen, eventually resulting in a chronic allergy.

Moreover, young babies have a relatively poor skin barrier in early life, and children with the poorest skin barrier are at increased risk of developing eczema and food allergy.

So, what can we do to help improve the skin barrier of babies to prevent this from happening?

Over the last 10 years, our team has been investigating an intervention to improve infants skin barrier in early life in a series of studies. We have been testing whether EpiCeram™, a novel skin barrier cream, can be applied safely to the skin of infants with a family history of allergies, and to determine if it can prevent the development of these conditions.

We have chosen EpiCeram™ for these studies as it has been specifically designed to restore skin barrier function as it contains physiological levels of the major building blocks of human skin (ceramides, free fatty acids and cholesterol).

We ask parents to apply this treatment twice per day for the first six months of life as a preventative strategy.

Our randomised controlled trial of 80 infants has shown very promising results, with approximately a halving of the risk of both eczema and allergic reactions to food allergens, a precursor to food allergy. These results held even at 12 months of age – six months after the treatment was stopped.

Two small published trials from other groups also support this form of intervention.

We are now undertaking a larger trial to confirm these results and test if this intervention prevents food allergy. While the results of our 80-infant trial were very promising, the results are far from definitive. We are now conducting an enlarged study of 760 infants called PEBBLES (Prevention of Eczema (and food allergy) By a Barrier Lipid Equilibrium Strategy) and are in the middle of recruiting participants.

It may be that understanding allergies and preventing them may be a lot less complicated than we’ve long thought.

To find out more about the study, you can visit our study website - www.mspgh.unimelb.edu.au/visit/pebblesstudy. If you would like to participate in this research, you need to live near Melbourne, be pregnant or have a very young baby (less than three weeks old) who has a family member with allergies. If you fit this description, you can contact us at pebbles-study@unimelb.edu.au or call 1800 875 127. The study is funded by the National Health and Medical Research Council.

Banner: Getty Images