RNA-Sequenced Tape Strips Differentiate Atopic Dermatitis From Psoriasis

By Marilynn Larkin

July 31, 2020

NEW YORK (Reuters Health) - RNA-sequenced (RNA-seq) tape strip profiling distinguished atopic dermatitis (AD) from psoriasis, potentially offering a minimally invasive alternative to skin biopsies for monitoring disease activity, researchers say.

"The next step is to materialize this into a test that is done routinely to differentiate diseases and direct patient care to provide a personalized medicine approach," Dr. Emma Guttman-Yassky of the Icahn School of Medicine at Mount Sinai in New York City told Reuters Health by email.

"They will definitely be an amazing alternative to skin biopsies, particularly for larger studies and longitudinal studies where sampling of skin at many time points is required," she said. "But I can also see it being used in the clinic for personalizing treatments in the future."

As reported in the Journal of Allergy and Clinical Immunology, Dr. Guttman-Yassky and colleagues identified a cutaneous molecular phenotype of AD and psoriasis that is consistent with previous biopsy studies, including genes and pathways that define and distinguish the two conditions, as well as a single gene accurately classifying these diseases.

They did this by obtaining 20 tape strips of lesional and nonlesional skin from AD and psoriasis patients, and 20 tape strips from controls. They analyzed the tapes using RNA-seq, and validated immune and barrier biomarkers using quantitative RT-PCR.

RNA-seq profiles were detected in 96 of 100 of samples (96%), with 4,123 and 5,390 genes differentially expressed in AD and psoriasis lesions versus in controls, respectively.

In patients with AD, nonlesional tape-stripped skin was more similar to lesional skin than to nonlesional skin of patients with psoriasis.

AD and psoriasis tissues both showed increases in levels of dendritic cell and T-cell markers (CD3, ITGAX/CD11c, and CD83). However, AD tissues skewed toward greater TH2 expression (IL-13, CCL17/TARC, and CCL18), whereas psoriasis demonstrated greater expression of products that were TH17-related (IL-17A/F and IL-36A/IL-36G), TH1-related (IFN-g and CXCL9/CXCL10), and innate immunity-related (nitric oxide synthase 2/inducible nitric oxide synthase and IL-17C).

In both AD and psoriasis, the researchers saw significant downregulation of terminal differentiation (FLG2 and LCE5A), tight junction (CLDN8), and lipid biosynthesis and metabolism (FA2H and ALOXE3) products.

In addition, nitric oxide synthase 2/inducible nitric oxide synthase expression, as determined by quantitative PCR, differentiated AD and psoriasis with 100% accuracy.

Dr. Guttman-Yassky said, "My take-home message to clinicians is to take part in studies that can promote personalized medicine that will ultimately benefit their practice, and one day these non-invasive approaches may be directly be used in the clinic."

The tape strips could be available for clinical practice "within a few years," she added.

Dr. Joseph Zahn, Director of Dermatopathology and Residency Associate Program Director at George Washington School of Medicine and Health Sciences in Washington, DC, commented in an email to Reuters Health, "I absolutely think this approach could be of use in both clinical trials as well as the clinic. With our ever-growing knowledge of various biomarkers, its use will only increase with time. For now, though, its utility will likely be limited to trials, as we haven't validated its use in the clinical setting quite yet."

"The biggest caveats right now are that the method can be slow to produce results and could potentially be expensive for patients and providers," he noted. "I would expect that both of these issues would be addressed in the future."

SOURCE: https://bit.ly/3fajeh8 Journal of Allergy and Clinical Immunology, online July 21, 2020.