Skin, the human body’s largest organ, operates much like an ecosystem or a community of living and non-living organisms that interact as a system. Long ago, scientists discovered that our skin is colonized by a diverse milieu of microorganisms, most of which are harmless or even beneficial to our health.
Immunologists at the University of Zurich in Switzerland have shown that our immune system is responsible for maintaining the balance on our skin. But when they researched how the immune system responds to a particular strain of fungus on the skin, they made an unusual discovery.
The Swiss scientists theorized that the same immune cells that protect us against the normally harmless Malassezia fungus might also play a fundamental role in triggering atopic dermatitis.
They conducted a study that found that interleukin-17 (IL 17) production by certain immune cells, which normally provide protection against uncontrolled fungal growth on the skin, also contribute to an overreactive immune response and the development of AD symptoms.
The researchers were able to demonstrate in mice as well as in humans that Malassezia fungi stimulate the immune system to produce IL 17.
When that happens, the Malassezia fungus becomes an allergen on the skin, so to speak, and triggers an overreaction of the immune system with the same inflammatory characteristics of AD.
“If this cytokine isn’t released or if the immune cells that produce interleukin-17 are missing, there is nothing to stop the fungus from growing and infesting the skin,” said Salomé LeibundGut-Landmann, professor of immunology at the University of Zurich.
“The findings of our study suggest that therapeutic antibodies that neutralize the effect of interleukin-17 could be an effective treatment for atopic dermatitis. These antibodies already exist and are being used to treat psoriasis with great success,” said LeibundGut-Landmann.
Like atopic dermatitis, psoriasis is a chronic inflammatory skin condition caused by an overactive immune system. ithin the past five years, the FDA has approved biologics for adults with moderate to severe psoriasis that target IL-17, including Saliq (brodalumab), Taltz (ixekizumab), and Cosentyx (secukinumab)—the latter of which is now in phase II clinical trials for adults with AD.