CPN2 alleviates cryptorchidism by inhibiting the NF-κB pathway and regulating immune responses.

Cryptorchidism, a common male reproductive disorder characterized by undescended testes, is associated with infertility and increased cancer risk. While its etiology remains incompletely understood, accumulating evidence suggests that immune-inflammatory responses contribute to disease progression. This study investigated the role of carboxypeptidase N subunit 2 (CPN2) in modulating immune activation and testicular pathology via the NF-κB signaling pathway. Key regulatory genes were identified through transcriptomic analysis, weighted gene co-expression network analysis (WGCNA), and machine learning approaches. A di-n-butyl phthalate (DBP)-induced rat model of cryptorchidism and CRISPR/Cas9-mediated CPN2 knockout rats were employed, alongside histological, immunohistochemical, Western blotting, and co-culture assays to explore immune activation and spermatogonial cell fate. CPN2 was identified as a pivotal factor that suppresses NF-κB activation and plasma cell infiltration. Its overexpression alleviated inflammatory cytokine production, preserved spermatogonial stem cell proliferation, and reduced apoptosis in both in vivo and in vitro models. These effects were reversed upon NF-κB activation, confirming the regulatory role of the CPN2/NF-κB axis. Our findings reveal that CPN2 mitigates cryptorchidism progression by modulating immune-inflammatory responses, highlighting it as a promising molecular target for non-surgical intervention in this condition.