Extracellular vesicles ameliorate intrauterine adhesion through Nrf2/GPX4-mediated ferroptosis suppression

INTRODUCTION: As pivotal functional mediators of probiotics, extracellular vesicles (EVs) play crucial regulatory roles in diverse disease processes. However, the mechanisms by which vaginal probiotic-derived EVs contribute to intrauterine adhesion (IUA) remain poorly understood. OBJECTIVES: To identify EVs derived from Lactobacillus crispatus NCU-28 and elucidate their anti-inflammatory and anti-fibrotic mechanisms. METHODS: EVs were isolated and purified from vaginal probiotics and systematically evaluated using both an IUA mouse model and an inflammatory cell model. High-throughput sequencing was integrated with multiple molecular biology techniques to assess the anti-inflammatory and anti-fibrotic effects of EVs and to elucidate the underlying molecular mechanisms. RESULTS: An endometrial inflammatory cell model was established, demonstrating that EVs served as the pivotal active components through which L. crispatus NCU-28 exerted anti-inflammatory and anti-fibrotic effects. Following isolation and purification from L. crispatus NCU-28 culture supernatants, EVs were further evaluated in an IUA mouse model. The results demonstrated that EV treatment significantly downregulated fibrotic markers, including α-SMA and TGF-β1; inhibited the release of pro-inflammatory cytokines such as IL-6 and IL-1β; and restored vaginal microbiota homeostasis. Mechanistic investigations revealed that EVs modulated ferroptosis through activation of the Nrf2/GPX4 signalling pathway. Furthermore, reverse validation using a ferroptosis agonist confirmed that EVs inhibited oxidative stress-induced ferroptosis, thereby promoting endometrial repair and suppressing fibrotic progression. CONCLUSION: This study identifies EVs as central functional components through which L. crispatus NCU-28 exerts anti-inflammatory and anti-fibrotic effects, and it delineates the mechanistic role of EVs in ameliorating IUA. These findings provide a basis for developing innovative probiotic EV-based treatment strategies.