The above graph shows the tendency for allergic symptoms to worsen with age - the allergic march

Allergy Today: Are skin microbes the key to halting the allergic march?

18 April 2018, Allergies, Immune Cell Biology, Microbiota

This article originally appeared in Summer 2017 issue of Allergy Today. Karmella has since successfully completed and defended her PhD and is now continuing at the Malaghan Institute as Dr. Naidoo.

Malaghan Institute director Professor Graham Le Gros and research officer Karmella Naidoo are exploring the relationship between skin microbiota and the development of allergic responses.

From the moment we are born, our bodies are learning to live with the countless microorganisms that make up our environment. Which ones are good, which ones are necessary and which ones are harmful?

The immune system is responsible for maintaining this extremely fine balance between keeping the helpful and removing what’s harmful. It’s not perfect, and in some cases the immune system categorises a benign organism as something potentially dangerous, and acts accordingly. This is knownbas allergic sensitisation: the body overreacting to something it shouldn’t. Over time, the response invariably becomes more severe, developing into what we know as an allergy.

This overreaction is a lifelong problem for many people, and tends to get worse as we age. This effect is known as the allergic march – an escalating series of symptoms that progressively involves more and more areas of the body, both inside and out.

Can we halt the allergic march?

Atopic dermatitis (eczema) is one of the first allergic conditions infants and young children develop and one of the first steps taken on the allergic march. By preventing the initial development of eczema through the monitoring of our skin microbes, can we potentially halt the allergic march before it begins?

“Absolutely,” says Professor Graham Le Gros, director of the Malaghan Institute of Medical Research. “Our immune system doesn’t exist by itself, it exists in close connection with the microbiota around our body. The skin microbiota play a clear role in the initiation of allergic responses.

“Understanding this relationship in more detail could lead to better ways of stopping the development of allergic diseases like eczema and food allergy, preventing the allergic march in individuals.”

The task of unravelling this relationship between skin microbes and atopic dermatitis has been the ongoing work of Malaghan Institute research officer, Karmella Naidoo. Karmella has spent the three years of her PhD, funded by the Nikau Foundation, working to establish models of AD to study in depth. What Karmella has found is the large role skin microbes play in its development.

“Atopic dermatitis patients have a completely different microbiota on the skin compared to healthy individuals,” says Karmella. “We know that certain species of bacteria, in particular Staphylococcal strains, colonise most of the skin of an individual with atopic dermatitis.”

What causes an imbalance in microbes?

This imbalance of otherwise harmless microbes in our skin plays an important role in developing allergic disease. But what causes the imbalance in the first place?

One potential candidate is the over- exposure to sanitation and hygiene products. Their overuse puts a strain on our skin microbiome, harming beneficial organisms and reducing the diversity of their population. This gives opportunists a chance to colonise, upsetting the balance and making us vulnerable to allergic sensitisation.

By understanding the many factors at play early on in childhood development, scientists like Karmella hope to one day prevent these kinds of diseases from forming in childhood.

“I think it’s multifactorial. There’s a genetic component, a strong environmental component and then there’s the microbes that all play a role in how the way your body is tolerised to harmless environmental materials.”

“By putting a stop to allergic sensitisation early on, there’s a good chance we’ll be able to halt the allergic march before it begins. In that, we are hypothesising that skin microbes will have a large role to play and are researching them intensively.”