Microbial-triggered integrated stress response in sulcular and junctional keratinocytes exacerbates immunopathology in periodontitis.

Periodontitis serves as a model for chronic inflammatory diseases, offering critical insights into immune regulatory mechanisms at the microbe-host interface. By integrating structural immunity theory with single-cell transcriptomics and multi-omics analyses, we investigated the microbial-epithelial-immune crosstalk in periodontitis. Single-cell transcriptomic analysis revealed robust interactions between immune cells and sulcular and junctional keratinocytes (SK/JKs) in the periodontitis epithelium. SK/JKs, being directly exposed to dental plaque biofilm, exhibit significant activation of endoplasmic reticulum stress (ERS), oxidative stress, and the integrated stress response (ISR) during periodontitis. Weighted gene co-expression network analysis (WGCNA) emphasized the central role of ISR in coordinating stress pathways and immune effector functions. Experimental validation demonstrated that Porphyromonas gingivalis (P. gingivalis) infection induces epithelial ISR, triggering an inflammatory cascade, while inhibition of ISR significantly reduces cytokine production. Mechanistically, ISR activation in SK and JK cells upregulates key inflammatory mediators (CXCL1, CXCL8, CXCL16, IL-6), promoting infiltration of plasma cells and neutrophils, and reshaping the local immune microenvironment, ultimately driving alveolar bone destruction in periodontitis. Our findings uncover an ISR-mediated structural immunity axis in SK/JKs during periodontitis, enhancing our understanding of the mechanisms underlying chronic inflammatory diseases.