External pressure induced the dysfunction of Sertoli cells via the Fas/FasL signaling pathway

Cryptorchidism, a condition where the testis fails to fully descend into the scrotum during development, is associated with elevated environmental temperatures and pressures, leading to male infertility and germ cell tumors. Factors such as oxidative stress and high temperatures contribute to infertility in cryptorchidism. This study aims to explore how external pressure affects Sertoli cells and discover new mechanisms affecting spermatogenesis in cryptorchidism. Sertoli cells were subjected to various pressure levels (0 mmHg, 25 mmHg, 50 mmHg, 100 mmHg) and durations (0 h, 2 h, 4 h) using an enzyme-linked immunosorbent assay (ELISA) to measure androgen binding protein (ABP) and inhibin B (INH B) secretion. Cell morphology changes were observed using immunofluorescence; apoptosis rates were measured with terminal-deoxynucleotidyl transferase mediated nick end labelling (TUNEL) assay and flow cytometry; ultrastructural variations were examined via transmission electron microscopy; and the expression of apoptosis-related proteins (Fas, FasL, caspase 3, and caspase 8) was analyzed through immunohistochemistry, real-time polymerase chain reaction (real-time PCR), and western blotting. The results showed that elevated pressure suppressed ABP and INH B secretion from Sertoli cells. Structural changes were observed under pressure, including cytoskeleton loosening and nuclear fragmentation. Apoptosis rates increased with higher pressure levels. Ultrastructural analysis revealed chromatin changes, apoptotic bodies, and mitochondrial alterations. Increased expressions of Fas and FasL were detected, along with elevated levels of caspase 3 and caspase 8. The caspase 8 inhibitor blocked pressure-induced apoptosis and caspase 3 activation, while the cytochrome C inhibitor did not show the same effect. Our findings suggested that external pressure induces apoptosis of Sertoli cells via the Fas/FasL signaling pathway, potentially contributing to male infertility associated with cryptorchidism.