In the United States, between 10 and 20 percent of children aged 10 and below have atopic eczema, and a total of 28 million Americans are affected by the condition.
The condition is more prevalent among children, and some affected infants go on to develop allergic rhinitis or asthma later in life. This is known as an "atopic march" – a phenomenon whose causes, mechanisms, as well as ways to prevent it have puzzled researchers for years.
Now, a new study brings us closer to understanding the roots of atopic march, as scientists at VIB Ghent University in Flanders, Belgium, searched for a cure for both asthma and atopic dermatitis.
The team was led by Dr. Julie Deckers, Prof. Karolien De Bosscher, and Prof. Hamida Hammad – all from Ghent University's Center for Inflammation Research.
Studying atopic march in mice
Dr. Deckers and colleagues created a mouse model of the atopic march, in which the rodents were exposed repeatedly to house dust mites through the skin, as well as in the lungs. House dust mites are known to trigger both eczema and asthma.
The researchers wanted to see if "relief of skin inflammation by glucocorticoids and PPAR [gamma] agonists might influence the subsequent development of asthma."
Glucocorticoids and PPAR gamma agonists are two anti-inflammatory compounds, which the researchers administered topically to the mice.
Firstly, their study revealed more insights into the complex development of the atopic march. "As predicted," the lead researcher explains, "our test showed that house dust mite-induced skin inflammation leads to aggravated levels of allergic airway inflammation."
"Yet, to our surprise," Dr. Deckers continues, "this response significantly differs from the reaction to direct exposure of house dust mites in the lungs without prior skin inflammation. These results have given us a deeper understanding of the complexity of the atopic march," the researcher adds.
A 'potent remedy' for childhood eczema
As for the effect of the combined anti-inflammatory compounds on both conditions, this was also quite successful.
"Cutaneous combined activation of [glucocorticoids and PPAR gamma agonists] reduced skin inflammation to a higher extent compared to single activation," write the authors.
"The combined therapy effectively alleviated [atopic dermatitis], but was insufficient at preventing allergic asthmatic response in the lungs," says Dr. Deckers.
This was done by counteracting the response of the so-called T helper 17 cells – a type of immune cell.
"However, the treatment did significantly reduce the severity of the asthma by counteracting one aspect of the specific immune response in the lungs. In this way, the therapy represents a potent remedy against allergic skin inflammation and the aggravation of atopic march."
Dr. Julie Deckers
In future, the scientists are looking to bring their findings to human clinical trials and simultaneously work on developing new therapies that could effectively stop the development of the atopic march.
Neither atopic dermatitis nor asthma have a known cure, so the need for prevention strategies for these conditions remains dire.