Thinking of psoriasis and atopic dermatitis (AD) as a spectrum, rather than separate diseases might lead to better understanding, and potentially better treatments, two authors have proposed in the journal Current Opinion in Immunology.
“A case can be made that psoriasis and AD exist across a spectrum where polar T-cell axes can be variably present and create some overlapping disease characteristics,” wrote authors Emma Guttman-Yassky, M.D., Ph.D., and James G. Krueger, M.D., Ph.D.
When these T-cell mediated inflammatory skin diseases are studied in European-American populations, the differences between them are clear in both T-cell polarity and cytokine arrays, the authors note.
Psoriasis is driven in large part by Th17 T-cells and the associated activation of IL-17, they said. In contrast, a strong driver of AD is Th2, which is associated with overproduction of IL-4 and IL-13.
However, subtypes including Asian-origin, pediatric, and intrinsic AD have a prominent IL-17 component. That, along with tissue patterning that overlaps with psoriasis histopathology, starts to build the case for a spectrum of immune disease, which is depicted graphically in the article.
“We used to think that atopic dermatitis was a purely Th2 disease,” Dr. Guttman-Yassky said in an interview with Dermatology Times. “We now know that it’s much more complex, and instead of being a homogeneous disease, it actually has different phenotypes. While Th2 activation is common to these phenotypes, they differ in activation of Th17 and Th22 T-cell axes, which show for example significant increases in Asians with AD.”
“So, we need to think about it as a continuum, and for different patient subsets with different phenotypes of atopic dermatitis, we need to think that maybe some treatments from the psoriasis arena may actually qualify,” said Dr. Guttman-Yassky, the Sol and Clara Kest Professor of Dermatology and Vice Chair for Research and the director of the Laboratory of Inflammatory Skin Diseases in the Department of Dermatology at Icahn School of Medicine at Mount Sinai Medical Center, New York, N.Y.Full Article