Fig. 3: Increased proinflammatory profiles coincide with altered differentiation patterns of tooth-associated keratinocytes.

a Due to single-cell annotation and in situ validation (Fig. 2; Supplementary Fig. 3), a draft model of the oral-to-tooth transition zone in humans is presented, with basal and suprabasal keratinocyte markers uniquely identifying the alveolar mucosa (AM), attached gingiva (AG), gingival margin (GM), sulcular epithelium (SK) and junctional epithelium (JK). b These markers allowed for KRT19-high keratinocyte (KC) cell subclustering for the first time (2504 cells in total), including gingival margin keratinocytes (GM), sulcular keratinocytes (SK), and junctional keratinocytes (JK). c A more granular draft (Tier 4) annotation of epithelial cells of the gingival attachment. d Assaying differentially expressed genes in periodontitis, SKs and JKs only share about a quarter of upregulated genes. JKs displayed nearly 125 unique upregulated genes in diseased cells. e Further analysis of basal and suprabasal (differentiating) SK and JK keratinocytes revealed unique cell signatures between basal and suprabasal cell types. This full list is included in Supplementary Data 1. f–i To understand SK and JK developmental progression and cell state alterations, we used partitioned-based graph abstraction (PAGA). f Examining the basal to suprabasal transition, JKs display altered gene expressed comparing health to disease cell types, including broader expression of KRT17 and more expression of JUND, COL17A1, and CDH3. Key differentiation genes such as SPRR family members were also downregulated. g JKs displayed robust cell signaling and inflammatory phenotypes, which appear exacerbated in disease states. h In SKs, differentiation-related genes were uniquely expressed compared to JKs in health but also appeared altered in disease along the basal to suprabasal trajectory. i SKs appeared generally less reactive compared to JKs in disease, with lower overall expression of effector molecules such as CXCL1, CXCL8, IL1A, IL1B, and IL1RN. Abbreviations: Merk Merkel Cells, LC langerhans cells, Mela melanocytes, Muc mucosa, SB suprabasal Keratinocytes; for others, see Fig. 1 legend. For this figure, n = 30-sample, 2504-cell for scRNAseq.