Differentiating psoriasis from eczema can be challenging for lesions presenting with atypical phenotype, minimal/chronic inflammation or in distinct anatomical locations (scalp, auricular, palmoplantar and flexural areas).
Unlike skin biopsies, tape stripping is a non-invasive tissue sampling technique. We aimed to further develop this tool to facilitate the diagnosis of psoriasis and eczema and identify a simple but robust non-invasive diagnostic algorithm.
Samples have been collected using CuDerm adhesive discs from psoriatic (n=35) and eczematous (n=21) skin and of healthy controls (n=23). Sample protein extraction was followed by peptide identification using liquid chromatography tandem mass spectrometry (LC-MS-MS), with data analysis in MaxQuant quantitative proteomics and Perseus software. Quantification of selected markers with biomarker potential was performed with ELISA based assays.
We identified a total of 690 proteins across tape stripping samples using mass spectrometry. Volcano plot analysis differentially identified 78 proteins in psoriasis and 45 proteins in eczema when compared to healthy controls. When directly compared psoriasis with eczema profiles, 18 epidermal proteins had significantly different expression, including IL-1 family member IL-36γ and keratinocyte-derived protease inhibitor, elafin. Unsupervised hierarchical cluster analysis identified a cluster of general inflammatory markers upregulated in both eczema and psoriasis, but not in healthy controls, as well as a protein cluster specific for plaque psoriasis.
Using this non-invasive, unbiased approach, we were able to identify a combination of biomarkers with a discriminatory potential for psoriasis and eczema and demonstrated their diagnostic specificity in clinically challenging cases. To our knowledge, this is the first study directly comparing proteomic data from psoriasis and eczema samples obtained via tape stripping.

Comparative mass spectrometry proteomics of epidermal samples obtained by non-invasive tape stripping from inflammatory skin diseases