Microbiota-Induced Activation of the Integrated Stress Response in Sulcular and Junctional Keratinocytes Amplifies Immunopathogenic Mechanisms in Periodontal Disease

Abstract

Periodontitis is driven by dysbiotic subgingival microbiota that trigger maladaptive host inflammation, yet the epithelial mechanisms converting microbial challenge into tissue destruction remain poorly defined. Here, we demonstrate that dysbiotic pathobionts chronically activate the integrated stress response (ISR) in human sulcular and junctional keratinocytes, transforming a cytoprotective pathway into a central amplifier of immunopathology. Multi-omics profiling of clinical biopsies and primary cultures revealed compartment-specific activation of PERK, GCN2, PKR, and HRI kinases, converging on eIF2α phosphorylation and sustained ATF4/CHOP signaling. This maladaptive ISR state directly amplifies NF-κB–driven pro-inflammatory cytokine production, primes NLRP3 inflammasome activation, and downregulates tight junction proteins, precipitating epithelial barrier failure and connective tissue invasion. Pharmacological inhibition (ISRIB, GSK2606414) or genetic ablation (EIF2AK3, ATF4) of ISR signaling restored barrier integrity, attenuated inflammatory mediator release, and significantly reduced alveolar bone loss in murine periodontitis models without perturbing microbial ecology. Spatial transcriptomics identified a disease-enriched ATF4⁺/CHOP⁺ keratinocyte subpopulation that colocalizes with immune infiltrates and epithelial erosion. Collectively, these findings position epithelial ISR activation as a critical mechanistic bridge between microbial dysbiosis and periodontal tissue destruction, highlighting host-directed ISR modulation as a promising adjunctive therapeutic strategy for managing chronic periodontitis.