Bacterial Extracellular Vesicles as Potential Promoting Factors for Oral Lichen Planus Pathogenesis

Oral lichen planus (OLP) is a chronic inflammatory disease characterized by an intensive infiltration of cytotoxic T cells, which causes keratinocyte death. Abnormal changes within keratinocytes might be critical for OLP onset and progression, but the pathogenic mechanism of OLP is still uncertain. The human oral microbiota, consisting of approximately 50–100 billion bacterial entities, encompasses around 200 dominant bacterial species. These bacteria continuously produce and release extracellular vesicles (EVs), which play a significant role in host-microbe interactions. However, the impact of these bacterial EVs on the progression of OLP has not been fully elucidated. In this study, through comprehensive database analysis and experimental validation, we observed that OLP lesions exhibit elevated inflammatory signatures and significantly increased phosphorylation of STAT3 compared to non-OLP tissues. Notably, EVs derived from key periodontal pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, were shown to induce an inflammatory response and activate STAT3 signaling pathways, closely mirroring the pathophysiological features observed in OLP. These results underscore the potential role of bacterial EVs in the pathogenesis of OLP and highlight STAT3 as a critical mediator in this process.