Reanalysis of the immunological characteristics of scalp psoriasis: a cross-sectional study using Olink proteomics

To analyze the molecular profile of adult patients with Scalp psoriasis (SP).

We assessed 92 inflammatory biomarkers in lesional scalp skin from SP patients (n = 20) and demographically comparable healthy controls (HCs, n = 12) using Olink high-throughput proteomics, and investigated the expression of Th2-type cytokines using ELISA in an independent cohort (contains 11 SP patients and 5 HCs).

We identified 28 differentially expressed proteins (DEPs) in lesional SP compared to HCs (FC ≥ ±1.2, adjusted p-value <0.05). We observed that SP exhibits a Th1/Th17/IL-12/IL-23-dominant molecular signature. GO clustering and KEGG pathway analyses demonstrated close interrelationships among cytokines, chemokines, and their receptors during the psoriatic inflammatory cascade. Moreover, our results indicated a down-regulation of Th2-type molecules in the SP group, evidenced by significantly reduced levels of IL-4 and IL-5. Notably, these decreases were negatively correlated with the scalp-specific Investigator's Global Assessment (ss-IGA) scores (IL-4: r = -0.78, p < 0.01; IL-5: r = -0.65, p < 0.05), which may lead to an imbalance characterized by an enhanced Th1/Th17/IL-12/IL-23 inflammatory response.

This proteomic profile provides a new perspective on the immunological pathogenesis of SP, suggesting an imbalance between Th2 and Th1/Th17/IL-12/IL-23 responses.