What Causes Eczema?

National Jewish Health physician Mark Boguniewicz, MD, discusses the two leading theories on the cause of eczema (atopic dermatitis.) He also talks about Filaggrin, a key protein in the skin, which is often missing in patients with severe eczema.

Video Transcript

The reason why our patients have this disease is an area of active research. There are two leading hypotheses or theories. One is called the outside-in hypothesis the other one is the inside-out hypothesis. So you can see this is a sort of chicken or egg sort of discussion. In the outside-in hypothesis, researchers believe that changes in that skin barrier lead to the various immune abnormalities that we see in our patients. Conversely in the inside-out hypothesis researchers believe that immune system abnormalities lead to that damaged skin barrier.

We've come to recognize that about half of our patients with more moderate severe persistent atopic dermatitis are missing a key building block protein in their skin. That protein is called Filaggrin or Filaggrin, and it contributes not only to that topmost layer of protective skin but it also helps by when it breaks down into its individual components to the hydration of the skin to keep the skin from drying out and cracking. And it also contributes to the pH or acidity of the skin which is important in protecting us against various microbial organisms that would like to colonize the skin.