Associations Between Skin Microbiome and Metabolome in the Pathogenesis of Atopic Dermatitis Patients With Scalp Involvement

Purpose: Atopic dermatitis (AD) is a chronic inflammatory skin condition influenced by various factors, such as the skin microbiome and metabolome. However, specific contributions of these factors to scalp involvement in AD still need to be explored. In this study, we aimed to assess the associations between the skin microbiome and metabolome in AD patients with scalp dermatitis and healthy controls (HCs). Methods: A total of 20 AD patients with scalp involvement and 16 HCs were recruited, and their skin samples were collected for analysis. Bioinformatic analysis and 16S rRNA metagenomic sequencing were performed, with gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) conducted for AD-associated skin metabolites. Spearman correlation analysis was used to identify the correlations between AD-associated skin bacteria and metabolites. Results: The results revealed significant differences in bacterial taxa and metabolites between the lesional and non-lesional scalp skin samples of AD patients (groups LS and NL, respectively) and those of HCs (group HC). Notably, group LS showed a significantly increased relative abundance of the genus Staphylococcus and a decreased abundance of Cutibacterium compared to group HC. The reduced abundance of Cutibacterium was also observed when comparing LS to NL. The GC-TOF-MS analysis identified 33 significantly decreased metabolites and 17 significantly increased metabolites in groups LS and NL compared with group HC. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that amino acid-related metabolism was significantly altered in the metabolic pathway between groups LS, NL, and HC. Furthermore, Spearman correlation analysis showed significant correlations of the altered bacteria genera and skin metabolites between the 3 groups. Conclusions: The results of this research provide valuable insights into the associations the skin microbiome and metabolome between groups LS, NL, and HC. Identifying these specific contributions may offer new avenues for understanding the pathogenesis of scalp involvement in AD patients and potentially lead to improving management strategies.