From the Journals

Study highlights potential advantages of tape strips over biopsy


 

FROM THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY

Collecting cells from the skin surface with adhesive tape strips is demonstrating a level of accuracy that is rivaling skin biopsies for atopic dermatitis and psoriasis, promising a minimally invasive approach for monitoring these and potentially other dermatologic diseases, according to the latest advances with this approach.

Dr. Emma Guttman-Yassky Courtesy Mount Sinai Health System

Dr. Emma Guttman-Yassky

“Tape strips are not going to fully replace biopsies, but we think they will have an important role in diagnosing and monitoring response to therapy by avoiding the potential scarring and pain of biopsy,” reported Emma Guttman-Yassky, MD, PhD, professor of dermatology and director of the laboratory inflammatory skin diseases at the Icahn School of Medicine at Mount Sinai Medical Center, New York.

The concept of using adhesive strips to remove surface skin cells for clinical study has been around for more than 20 years, but there has been recent progress. A newly published study, which compared skin from patients with atopic dermatitis (AD) or psoriasis with that of controls, was characterized as “the most comprehensive tape strip molecular profiling in any inflammatory skin disease to date and the first to fully characterize and compare AD to psoriasis,” wrote Dr. Guttman-Yassky, the senior author, and coauthors.

It also appears to be a leap forward. RNA sequencing detected thousands of differentially expressed genes reflecting immune and barrier biomarkers characteristic of the molecular phenotypes of atopic dermatitis and psoriasis. These were not only found to be consistent with biopsy studies but identified additional unique genes and pathways relevant to their pathological signature.

“In the past, the success rate for transcriptome sequencing even for a more limited panel of proteins was approaching 50% when considering both lesional, nonlesional skin, and healthy skin, but we are now approaching 100% for sample recovery and for analysis of RNA and genes,” Dr. Guttman-Yassky said in an interview.

Tissue samples were obtained with tape strips from lesional and nonlesional skin from 20 patients with AD and 20 patients with psoriasis. Compared with 20 tape strips from controls, they were evaluated with RNA sequencing followed by quantitative real-time polymerase chain reaction of immune and barrier biomarkers.

The sample recovery rate was 96% overall and 95% or better regardless of whether the skin was lesional or nonlesional.

With RNA sequencing of more than 20,000 transcripts, including multiple cellular, immune, and barrier biomarkers, an enormous amount of data was generated, but the key finding is that these diseases are readily distinguished with profiling based on tape strips.

Although numerous biomarkers were shared, “tape strips completely discriminate between atopic dermatitis and psoriasis with a degree of reliability that is comparable to skin biopsy,” Dr. Guttman-Yassky said.

One of the biomarkers, expression of nitric oxide synthase 2/inducible nitric oxide synthase, distinguished AD from psoriasis with 100% accuracy. As previously reported in biopsy studies, other biomarkers collectively associated AD with a profile related to a Th2-type inflammatory response and psoriasis with a Th17-type inflammatory response.

Tape strips also confirmed significant pathology in the nonlesional as well as the lesional skin of patients with AD or psoriasis. This included an increase in Th2-type products, such as interleukin-4 and IL-13, in nonlesional skin of atopic dermatitis and Th17-type products, such as IL-17, in nonlesional skin of psoriasis.

Some biomarkers of AD and psoriasis had an even greater differentiation in tape strips than previously reported from biopsy studies, according to Dr. Guttman-Yassky. In this study, tape strips also captured more differentially expressed genes than previously reported with biopsies.

One potential limitation of tape strips is that the RNA isolation process is time consuming, but this might be less of an issue in routine clinical use if there is a more refined number of biomarkers that are targeted or if technological improvements simplify processing, Dr. Guttman-Yassky pointed out.

To develop clinical utility for tape strips beyond AD and psoriasis, more work is needed to standardize the depth of sampling, which is variable with tape strips, she noted. Depth is relevant to the analysis of gene expression and mRNA activity of each dermatologic disease.

“Tape strips remain a research tool for now, but we do think that this technique can be refined and employed for clinical purposes, including diagnosis and monitoring response to treatment,” she said.

Relative to biopsy, the advantages are not difficult to envision. Dr. Guttman-Yassky, who recently published a study of tape strips for evaluating AD in children emphasized that tape strips are generally painless.

“Patients really do not mind tape strips,” she said. Although she believes that tape strips are providing unique insight into the pathology of inflammatory diseases not necessarily available with biopsy, she emphasized the practical value. Not least, “these could really help when the goal is to evaluate response to therapy over time.”

Another investigator who has conducted studies with tape strips, Maja-Lisa Clausen, MD, PhD, also thinks tape strips are likely to become routine clinical tools.

“Once the basis research, validation, and data are out, I think numerous companies will be ready to develop machines for more quick and easy processing, compared to the more labor intensive process that is used today for research,” explained Dr. Clausen, who is in the department of dermatology, Bispebjerb Hospital, University of Copenhagen.

She considers tape strips particularly promising for children, but she thinks the biomarker profiling made possible by these strips might be leading to personalized treatment programs for dermatologic diseases.

“What we need is further validation; which tape to use, how deep, and the importance of storage, which is a big issue in the clinic,” Dr. Clausen said in an interview.

Dr. Guttman-Yassky has financial relationships with multiple pharmaceutical companies, including those with therapies for psoriasis.

SOURCE: Guttman-Yassky E et al. J Allergy Clin Immunol. 2020 Jul 9. doi: 10.1016/j.jaci.2020.05.048.

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