Inactivation of the leukemia inhibitory factor/signal transducer and activator of transcription 3 pathway: a pivotal mechanism in adenomyosis-related embryo implantation failure

BACKGROUND: Adenomyosis (AM) is frequently associated with compromised embryo implantation. The leukemia inhibitory factor (LIF)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is crucial for endometrial receptivity; however, its mechanistic role in AM-related implantation failure remains insufficiently elucidated. This study aimed to investigate the inactivation mechanism of the LIF/STAT3 pathway in AM and to evaluate a novel nanotherapeutic strategy for restoring implantation capacity. METHODS: Clinical endometrial samples from AM patients and controls were analyzed. A three-dimensional (3D) co-culture system simulating the endometrial microenvironment was established. Interventions were performed using a tofacitinib-loaded biomimetic nanogel (Tofa-NG). Comprehensive analyses included bulk RNA Sequencing (RNA-seq), immunohistochemistry (IHC), RT-qPCR, proteomics, inflammatory cytokine profiling, and metabolomics to dissect the pathological links. RESULTS: The LIF/STAT3 signaling pathway was significantly downregulated in the endometrium of AM patients, correlating directly with implantation failure. Pathologically elevated inflammatory cytokines suppressed LIF expression via NF-κB pathway activation, exacerbating the inflammatory microenvironment. Metabolomic profiling revealed a strong association between LIF/STAT3 pathway inactivation and aberrant cellular energy metabolism. The engineered Tofa-NG facilitated targeted drug delivery, effectively mitigated local inflammation, and successfully reactivated the LIF/STAT3 pathway. Consequently, this intervention significantly improved the embryo implantation success rate in the experimental model. CONCLUSION: This study identifies the inactivation of the LIF/STAT3 pathway as a central mechanism underlying embryo implantation defects in AM, intricately linked to chronic inflammation and metabolic dysregulation. The Tofa-NG strategy demonstrates promising therapeutic potential by rectifying the signaling deficit and ameliorating the endometrial microenvironment. These findings provide a novel theoretical foundation for developing targeted, personalized treatments for infertility associated with AM.