Fig 1: Melanin transfers to the skin dermis by disrupting the basal membrane. (A) Masson-Fontana staining and quantification of melanin contents in the skin dermis. N = 12. The 40× scale bar is 500 μm and the 200× scale bar is 100 μm, respectively. (B) Quantification of the isolated melanin from the separated dermis. N = 12. (C) The Volcano map of DEGs between KN and KD basal cells. (D) GO and KEGG orthologs of the DEGs in basal cells. (E) Violin plots represent the expression of inflammation, tight junction, and basal marker genes in basal cells from KN and KD skins. (F) qPCR analysis of inflammation and tight junction genes in KN and KD skins. N = 12. (G) ELISA analysis of CCL2 and S100A8/A9 in KN and KD skins. N = 12. (H) qPCR analysis of COL17A1 and KRT15 in KN and KD skins. N = 12. (I) Immunohistochemistry of COL17A1 on skin sections from the KN and KD. N = 12. (J) Protein expression of COL17A1 in KN and KD skins. (K) The schematic diagram of ex vivo explants culture and intraepidermal melanin injection. (L) qPCR analysis of inflammation genes after melanin treatment in skin explants. (M) ELISA analysis of CCL2 and S100A8/A9 after melanin treatment in skin explants. (N-O) mRNA and protein levels of COL17A1 in skin explants after melanin treatment. (P) CCL2 and S100A8/A9 protein expression in TE 354.T basal cells. (Q) The schematic diagram of co-culture of keratinocytes, basal cells, and fibroblasts. (R) Cell permeability assay. (S) Melanin content in cell medium and fibroblast cells with or without melanin treatment. The experiments in P-S were repeated three times independently. *P < 0.05; **P < 0.001; ***P < 0.001