Minimally invasive test strips subjected to RNA sequencing may be an effective method for detecting distinct immune and barrier signatures in lesional and nonlesional skin of patients with atopic dermatitis (AD) and psoriasis, suggesting RNA sequencing tape strips could represent an alternative to biopsies for monitoring biomarkers of AD and psoriasis activity, according to a study findings published in the Journal of Allergy and Clinical Immunology.
The study enrolled 20 adults with moderate to severe AD (mean age, 31.0±13.8 years), 20 adults with psoriasis (mean age, 42.6±15.4 years), and 20 healthy volunteers (mean age, 40.3±15.7 years). Study investigators collected 20 consecutive large D-Squame tape strips from the lesional and nonlesional skin of patients with AD and psoriasis as well as from healthy control participants. The RNA was extracted from each strip (mean RNA yield, 39.7±56.6 ng), and the tape strips were subjected to quantitative RT-PCR for the validation of immune and barrier biomarkers.
Approximately 96% of the 100 samples had detected RNA sequencing profiles. A total of 4123 genes were differentially expressed in AD, and 5390 genes were differentially expressed in psoriasis lesions compared with those of healthy control participants (fold change ≥2; false discovery rate [FDR] <0.05). The nonlesional tape-stripped skin from patients with AD was more similar to lesional skin vs nonlesional skin from patients with psoriasis. Increases in dendritic cell and T-cell markers (CD3, ITGAX/CD11c, and CD83) were observed in both AD and psoriasis tissues. Tissues of patients with AD had elevated levels of TH2 (IL-13, CCL17/TARC, and CCL18) compared with those of control participants.
Psoriasis tissues had higher levels of 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) products (FDR <0.05). Significant downregulation of terminal differentiation (FLG2 and LCE5A), tight junction (CLDN8), and lipid biosynthesis and metabolism (FA2H and ALOXE3) products was observed in tissues of AD and psoriasis (FDR <0.05). Psoriasis and AD were differentiated by nitric oxide synthase 2/inducible nitric oxide synthase expression with 100% accuracy.
A limitation of tape strips includes the “time-consuming RNA isolation process,” according to the researchers of this study, in addition to the depth differences of tape strips for different conditions.
Considering tape strips offer 100% discrimination between psoriasis and AD, the investigators of this study suggest that this method “may provide a useful alternative to biopsies for tracking cutaneous disease activity in longitudinal studies and clinical trials.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
He H, Bissonnette R, Wu J, et al. Tape strips detect distinct immune and barrier profiles in atopic dermatitis and psoriasis [published online July 9, 2020]. J Allergy Clin Immunol. doi: 10.1016/j.jaci.2020.05.048.