Across 1,068 participants in a 3-year, four-country study, scalp microbiome patterns track alopecia severity, progression, and treatment response. We built the Hair Microbiome Health Index (HMHI) to flag and predict disease course. A multi-omics Microbe–Metabolites–Host Crosstalk model shows Cutibacterium acnes converts tryptophan to indole, overactivating AHR in sebocytes, triggering CXCL12 release, recruiting CXCR4+ NKT cells, and stalling follicle growth. Targeting microbe–host signaling offers a therapeutic path for hair loss.

• code/seurat_utils.R + code/cellchat_utils.R: streamlined Seurat and CellChat workflows.
• code/microbiome_utils.R + code/microbiome_prediction_utils.R: microbiome stats, ordination, and prediction helpers.
• code/enrichment_utils.R + code/kegg_utils.R + code/limma_utils.R: differential testing and KEGG/GSEA enrichment.
• code/metabolism_utils.R + code/heatmap_utils.R + code/plot_utils.R + code/theme_utils.R: metabolite cleanup plus ready-made plots, heatmaps, and themes.
• code/multiomics_utils.R + code/lefse_utils.R + code/iobr_utils.R + code/tempdir_utils.R: multi-omics merging, LEfSe wrappers, signature scoring, and fixed temp directories.

• Single-cell RNA-seq and spatial transcriptomics: GSA-Human HRA016071.
• Metagenome and 16S rRNA gene sequences: ENA PRJEB103845.

Skin microbiota dysbiosis inhibit hair follicle regeneration; Under Review, 2025

Gaofeng Wang ([email protected])