APOA1, DEFB103A_DEFB103B and DSG3 Are Novel Circulating Biomarkers of Psoriasis.

Psoriasis is a chronic inflammatory autoimmune skin disease for which no standardised and reliable molecular biomarkers of disease course or activity are currently available. Here, we aimed to identify serum biomarkers of psoriasis. Serum samples from 40 patients with psoriasis and 40 healthy volunteers were analysed using ELISA and Proximity Extension Assay proteomics. ELISA revealed significantly increased serum levels of AGO2 and APOA1 in psoriatic patients versus controls, with a strong association between APOA1 and psoriasis (OR = 20.72, 95% CI of 4.57-93.87, p = 0.000137). Targeted serum proteomics additionally identified 35 differentially expressed proteins, including well-known psoriasis drivers (e.g., top upregulated IL17A and SERPINB4). The most downregulated was adrenomedullin (ADM, FC = -10.12). For 14 altered proteins, no previous direct associations with psoriasis were reported. Among them, DEFB103A_DEFB103B and DSG3 showed the best discrimination between psoriasis and control samples, while SERPINB4 correlated with psoriasis severity. APOA1, DEFB103A_DEFB103B, and DSG3 emerge as novel candidate circulating psoriasis biomarkers, and SERPINB4 as a biomarker of psoriasis severity. The functional role of DSG3 and other newly identified proteins (ACRV1, HAO1, ADH4, GPD1, GFER, PTGES2, DSG3, AFAP1L1, GALNT3, RASGRP2, MAP2K6, LXN, NBEAL2, and VPS54) in psoriasis requires further studies.