AIM2-mediated senescence of gingival fibroblasts exacerbates inflammaging in periodontitis

To explore how AIM2 contributes to inflammation-associated senescence in gingival fibroblasts and to clarify its role in periodontal tissue deterioration, gingival tissues from healthy controls and periodontitis patients were subjected to multiplex immunofluorescence staining to assess AIM2, the DNA damage marker γH2AX, the senescence marker p16^INK4A, and inflammatory mediators including IL-6, IL-1β, caspase-1, ASC, and GSDMD. Human gingival fibroblasts (hGFs) with AIM2 overexpression or siRNA-mediated knockdown were established, followed by analyses of SASP profiles, DNA damage, and alternative splicing via RNA-seq. Periodontitis tissues exhibited significantly worse periodontal parameters and showed marked AIM2 upregulation, with mean fluorescence intensity increased by 2.7-fold in the epithelium and 2.4-fold in the lamina propria compared with HC, accompanied by elevated caspase-1, GSDMD, and IL-1β. AIM2 levels correlated positively with bleeding on probing and attachment loss, and multiplex immunofluorescence revealed accumulation of AIM2⁺/γH2AX⁺/p16^INK4A + senescent fibroblasts co-expressing IL-6 in periodontitis lesions. In hGFs, AIM2 overexpression increased p16^INK4A expression and ROS while reducing apoptosis, whereas AIM2 knockdown reversed these changes, indicating a shift toward a survival-senescence phenotype with enhanced SASP. RNA sequencing of AIM2-overexpressing hGFs showed enrichment of inflammatory, ribosome/spliceosome, and p53-related pathways, together with widespread alternative splicing in genes involved in lipid metabolism, innate immunity, and DNA damage responses, linking AIM2 to coordinated transcriptional and post-transcriptional regulation of inflammaging. AIM2 therefore appears to function as a potential regulatory node integrating DNA damage and senescence signaling in gingival fibroblasts, sustaining a positive feedback loop between chronic inflammation and cellular senescence in periodontitis. Targeting AIM2 may help disrupt the inflammaging cycle and could represent a potential strategy for mitigating periodontal tissue destruction and age-related inflammatory deterioration.