Abstract Background Oral lichen planus (OLP) is a chronic immune-mediated inflammatory disease affecting the oral mucosa, with tongue lesions being clinically significant due to their association with oral cancer risk and taste dysfunction. However, the layer-specific molecular heterogeneity of the basal layer (BL), spinous layer (SL), and lamina propria (LP) in tongue OLP remains poorly characterized, limiting mechanistic understanding and therapeutic development. Materials and Methods We employed spatial proteomics combined with laser capture microdissection (LCM) to analyze layer-specific protein expression in tongue OLP lesions (with lymphocyte infiltration) and adjacent non-lesional tissues from 3 patients. Histopathological validation via immunohistochemistry was performed on samples from an expanded cohort of 10 OLP patients and 10 normal tongue dorsum tissue samples. Multiplex fluorescent staining was utilized to analyze the spatial association between KRT17 and relevant immune cells/cytokines. In vitro functional assays, including TNF/IFN-γ or LPS-induced inflammation models, scratch wound healing, apoptosis detection, and KRT17 knockdown, were conducted in human oral keratinocytes (HOKs) to explore mechanistic roles of key proteins. Results A total of 4434 proteins were identified, revealing distinct layer-specific dysregulation: 183 upregulated and 98 downregulated proteins in the BL; 262 upregulated and 330 downregulated in the LP; and 91 upregulated and 112 downregulated in the SL. In the BL, immune activation markers (LCP1, RAC2, KRT17) were enriched, while metabolic enzymes (ASS1, PHGDH) were suppressed. The LP showed upregulated pro-inflammatory mediators (CORO1A, IL16) and downregulated extracellular matrix proteins (TNXB, KRT9). The SL exhibited disrupted differentiation markers (TGM3, KRT13) and innate immune molecules (MX2, ISG15). Functional enrichment analyses confirmed layer-specific pathogenic axes: immune-metabolic crosstalk in the BL, inflammatory-stromal loops in the LP, and differentiation defects in the SL. Multiplex staining revealed spatial correlation between KRT17, T cell infiltration, and IL-1β. In vitro, KRT17 knockdown attenuated LPS-induced inflammation (IL-6, IL-1β), was accompanied by restored HOK migration, and reduced apoptosis. Conclusion Our study uncovers layer-specific molecular landscapes in tongue OLP and identifies KRT17 as a candidate implicated in immune-epithelial crosstalk, providing novel insights into pathogenesis and a potential direction for future therapeutic exploration.
Yuanbo et al. (Wed,) studied this question.