[Metabolic characteristics of the healthy scalp microenvironment based on spatial metabolomics and its comparison...

Objective: To analyze the metabolic characteristics of the healthy scalp microenvironment using spatial metabolomics and to compare them with those of psoriasis lesions. Methods: Healthy skin tissue samples from various body sites were prospectively collected from patients undergoing skin biopsy in the Department of Dermatologic Surgery, Shanghai Dermatology Hospital between March 2024 and March 2025. Spatial metabolomics was performed to analyze metabolite differences between scalp skin and skin from other body regions (control group). Metabolic pathway analysis was conducted using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Additionally, dataset GSE13355 (containing psoriatic lesional skin and healthy skin from healthy individuals) was downloaded from the Gene Expression Omnibus (GEO) database. Differential gene expression analysis was performed between psoriatic lesions and healthy control skin followed by KEGG enrichment analysis of the differentially expressed genes. Results: A total of 40 healthy skin tissue samples (2 cm×3 cm) were collected from 12 different body sites, including 4 scalp samples and 36 control samples. Spatial metabolomics identified 375 differential metabolites, of which 274 were upregulated in the scalp. The scalp exhibited enrichment of lipid and acidic metabolites, including fatty acyls, glycerides, glycerophospholipids, sphingolipids, organic acids and derivatives, and amino acids and metabolites (all P<0.05). KEGG pathway analysis revealed that scalp differential metabolites were primarily enriched in lipid metabolism and skin function-related pathways, particularly bile secretion, glycerophospholipid metabolism, and sphingolipid metabolism. KEGG enrichment analysis based on the GSE13355 dataset from the GEO showed significant enrichment of pathways related to unsaturated fatty acid biosynthesis, fatty acid metabolism, and cholesterol metabolism in psoriatic lesions (all P<0.05). These metabolic characteristics were similar to those observed in normal scalp tissue. Conclusions: The healthy scalp region exhibits distinct lipid and acidic metabolic characteristics, while psoriasis lesions show disturbances in both lipid and acidic metabolism. Both share similar metabolic characteristic profiles.