Bacillus Coagulans Secretes Extracellular Vesicles and Modulates the Proliferation of Conjunctival Epithelial Cells via the P53/CDKN1A Signaling Pathway

To investigate the microbial strains in pterygium patients' tear samples via 16S rRNA sequencing and evaluate their impact on human conjunctival epithelial cells (HConEpics) and pterygium fibroblasts (HPFs) proliferation. Tear samples were cultured aerobically and anaerobically on blood agar plates. Bacterial colonies were characterized by 16S rRNA sequencing. Proliferation of HConEpics and HPFs was assessed using CCK-8 and EDU assays. The role of bacterial extracellular vesicles (EVs) was explored using the exosome inhibitor GW4869. EVs were isolated and characterized by transmission electron microscopy and nanoparticle tracking analysis (NTA), with DIL staining confirming their internalization by host cells. Transcriptomic sequencing and the SIRT2-IN-11 inhibitor were used to elucidate the molecular mechanisms and regulatory pathways. 16S rRNA analysis revealed a significant reduction in the concentration of Bacillus coagulans (BC) in pterygium patients. BC significantly promoted HConEpics proliferation while inhibiting HPFs proliferation. GW4869 significantly reduced the stimulatory effect of BC culture supernatant on HConEpics proliferation, confirming EVs-medicated regulation. BC-derived EVs, isolated by ultracentrifugation, were internalized by HConEpics, promoting proliferation and inducing G1 phase cell cycle accumulation. These EVs also inhibited TGF-β-induced damage to HConEpics. Transcriptomic sequencing identified the p53 pathway as a key regulatory pathway, further clarified by SIRT2-IN-11. This study offers novel insights into pterygium pathogenesis and identifies potential therapeutic targets.