Emodin alleviates testicular ischemia-reperfusion injury through the inhibition of NLRP3-mediated pyroptosis.

Ischemia-reperfusion injury (IRI) is a major cause of injury after testicular torsion and can lead to permanent impairment of spermatogenesis. Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) has potent anti-inflammatory effects and may be protective against IRI in various organs. Herein, we evaluated the effects of emodin on pyroptosis in spermatogenic cells and its role in the process of testicular IRI. A testicular torsion/detorsion (TTD) mouse model and an oxygen-glucose deprivation/reperfusion (OGD/R) germ cell model were established. Hematoxylin and eosin staining was performed to evaluate the testicular ischemic injury. The expression of pyroptosis-related proteins and reactive oxygen species production in testis tissues were detected using Western blotting, quantitative real-time PCR, malondialdehyde and superoxide dismutase assay kits and immunohistochemistry. Cell viability and cytotoxicity were evaluated using Cell Counting Kit-8 and lactate dehydrogenase assay kit. Enzyme-linked immunosorbent assay, immunofluorescence and immunoblotting were performed to assess inflammatory protein levels. The results revealed that pyroptosis and inflammation levels were upregulated after testicular IRI, and emodin inhibited inflammation and pyroptosis by acting on NOD-like receptor thermal protein domain-associated protein 3 (NLRP3). Emodin exerts protective effects on testicular IRI by acting on the NLRP3 signaling pathway and inhibiting IRI-mediated pyroptosis. Emodin treatment attenuated testicular IRI and inhibited pyroptosis. Inhibitory effects of emodin on pyroptosis were attributed to the inhibition of NLRP3 inflammasomes. Thus, emodin could be an alternative treatment for testicular IRI.