Hydrogel Micropatch and Mass Spectrometry–Assisted Screening for Psoriasis-Related Skin Metabolites

BACKGROUND Psoriasis is a chronic, immune-mediated inflammatory skin disease. Screening skin metabolites could unravel the pathophysiology of psoriasis and provide new diagnostic approaches. Due to the lack of suitable methodologies for collecting scarce amounts of skin excretions, the psoriatic skin metabolome has not been extensively studied. METHODS We implemented biocompatible hydrogel micropatch probes combined with mass spectrometry to investigate the skin metabolome. This noninvasive approach was applied to examine samples obtained from 100 psoriatic patients and 100 healthy individuals. We also developed custom data treatment tools and used chemometric and statistical tools to reveal the alterations in the skin metabolome caused by psoriasis. RESULTS The proposed methodology enabled us to capture alterations in the composition of skin excretions caused by the disease. Chemometric analysis revealed the major differences between the metabolomes of psoriatic skin and healthy skin. Several polar metabolites were positively (choline and glutamic acid) or negatively (urocanic acid and citrulline) correlated with the plaque severity scores. The amounts of these metabolites in the excretions sampled from psoriatic skin were significantly different (P < 0.001) from the excretions sampled from healthy skin. The role of biological variability and various confounding factors, which might affect the skin metabolome, was also investigated. CONCLUSIONS Sampling lesional and healthy skin with the hydrogel micropatch probes and subsequent direct mass spectrometry scanning provided information on the alterations in the skin metabolome caused by psoriasis, increasing the understanding of the complex pathophysiology of this disease.