Novel, non-invasive approaches for the diagnosis of inflammatory skin diseases

Psoriasis and eczema, among the most common dermatological conditions, are complex inflammatory dermatoses with distinguished underlying pathomechanisms. However, their similar clinical appearance at certain anatomical locations or in case of minimal or chronic inflammation often represents a diagnostic challenge. Establishing the correct diagnosis is essential not only from a therapeutic perspective, but also for correctly assessing, treating and potentially preventing important associated comorbidities. Skin biopsy followed by histopathology is the current diagnostic gold standard. Nevertheless, it is an invasive, costly procedure requiring specialised skills and equipment, which limits its clinical and research use.
This thesis therefore focused on tape stripping and its potential 1) as a non-invasive diagnostic tool to distinguish psoriasis from eczema with the identification of disease specific biomarkers, 2) as a research tool to facilitate the pathomechanistic understanding of these, 3) to detect early molecular changes in subclinical inflammation, 4) in the prediction of therapeutic response and disease follow up.
The main results of the thesis are the identification of IL36ү and elafin as highly specific and sensitive psoriasis biomarkers which allow its differentiation from eczema and the use of tape stripping as a non-invasive diagnostic tool even in clinically challenging cases. Secondly, 644 proteins across lesional, non-lesional and healthy tape stripping samples have been identified through mass spectrometry, with 90 proteins being differentially expressed between psoriasis and healthy samples, with a potential use in molecular subtyping. Furthermore, subtle molecular changes in non-lesional samples were successfully identified. Finally, preliminary data in cell culture experiments showed modulation of IL36ү and/or elafin expression following psoriasis-relevant treatments.
Overall, tape stripping proves to be a viable non-invasive method to identify different patterns of epidermal inflammation, facilitate diagnostic accuracy, treatment follow up and personalized medicine approaches, which could complement and even replace biopsies in the future.