Efferent ductule epithelium orchestrates reproductive immune homeostasis under inflammatory stress.

Immune dysregulation is increasingly recognized as a key contributor to male infertility, yet the role of the efferent ductules in reproductive immune homeostasis remains unexplored. Located between the immune-privileged testis and the epididymis, efferent ductules are essential for male fertility by reabsorbing over 90% of testicular fluid and maintaining sperm in suspension through the coordinated activity of reabsorptive primary ciliated cells (RPCCs) and multiciliated cells (MCCs). Using complementary in vivo and in vitro approaches, we investigated the contribution of efferent ductule epithelial cells to innate immunity. In a mouse model of lipopolysaccharide (LPS)-induced epididymitis, efferent ductules displayed significant interstitial neutrophil infiltration and abnormal sperm accumulation, indicating disrupted local homeostasis. Both mouse and human epithelial cells expressed Toll-like receptor 4, supporting a role in pathogen sensing. Transcriptomic analyses showed MCCs enriched in cilia-related genes, while RPCCs preferentially expressed genes involved in signaling and inflammation. To further explore epithelial immune function, we developed 3D organoid models recapitulating key features of efferent ductules. Upon LPS stimulation, these organoids mounted a robust innate immune response, secreting cytokines, chemokines, and growth factors, consistent with in vivo observations. Together, these findings identify efferent ductule epithelial cells as an upstream immunological checkpoint and establish organoids as a valuable model to study efferent ductule epithelial cells function in male reproductive health.