Riboflavin Attenuates Fluoride-Induced Testicular Injury via Interleukin 17A-Mediated Classical Pyroptosis.

Male reproductive toxicity of fluoride is of great concern worldwide, yet the underlying mechanism is unclear. Pyroptosis is a novel mode of inflammatory cell death, and riboflavin with anti-inflammatory properties has the potential to protect against fluoride damage. However, it is unknown whether pyroptosis is involved in fluoride-induced testicular injury and riboflavin intervention. Here, we first found that riboflavin could alleviate fluoride-caused lower sperm quality and damaged testicular morphology by reducing pyroptosis based on a model of ICR mice treated with NaF (100 mg/L) and/or riboflavin supplementation (40 mg/L) via drinking water for 13 weeks. And then, together with the results of in vitro Leydig cell modelsm it was confirmed that the pyroptosis occurs predominantly through classical NLRP3/Caspase-1/GSDMD pathway. Furthermore, our results reveal that interleukin-17A mediates the process of pyroptosis in testes induced by fluoride and riboflavin attenuation according to the results of our established models of riboflavin- and/or fluoride-treated IL-17A knockout mice. The results not only declare a new mechanism by which fluoride induces testicular injury via interleukin 17A-mediated classical pyroptosis but also provide evidence for the potential clinical application of riboflavin as an effective therapy for fluoride toxicity.

Chronic arsenic exposure lowered sperm motility via impairing ultra-microstructure and key proteins expressions of sperm acrosome and flagellum formation during spermiogenesis in male mice.

Arsenic (As) poisoning and its potential reproductive functional lesions are a global environmental concern. Recent studies shown that spermiogenesis tends to be a major target process in arsenic-induced male infertility, however, the underlying mechanisms are not fully illuminated. In the present study, 32 fertility related indices including sperm motility, dynamic acrosome formation and sperm flagellum during spermiogenesis in testes were evaluated in adult male mice treated with 0, 0.2, 2, and 20 ppm As2O3 via drinking water for 180 consecutive days. The results showed that out of 32 indices, 11, 25, and 29 indicators were changed statistically by 0.2-, 2-, and 20- ppm As2O3 treatment compared to the controls (0 ppm As2O3), respectively, which reveals a significant dose-dependent relationship. For details, sperm motilities were significantly decreased by 18.85%, 32.47% and 29.53% in three As2O3 treatment groups compared to the control group. Meanwhile, the ultra-structures of acrosome formation and sperm flagellum in testes have been altered by chronic arsenic exposure. Furthermore, arsenic decreased the mRNA expressions of 11 out of 13 genes associated with acrosome biosynthesis and 11 out of 12 genes related to flagellum formation in testes, particularly, down-regulated DPY19L2, AKAP3, AKAP4, CFAP44 and SPAG16 were further confirmed at the protein levels by western blotting. Taken together, chronic arsenic exposure declines male fertility by disorganizing dynamic acrosome and flagellum formation in testes. Especially, DPY19L2, AKAP3, AKAP4, CFAP44, and SPAG16 maybe the potential targets in this process. These results may offer not only a new insight to the mechanism of arsenic-induced male reproductive toxicity, but also provide a clue for the diagnosis and therapy of arseniasis.

Arsenic induces dysfunctional autophagy via dual regulation of mTOR pathway and Beclin1-Vps34/PI3K complex in MLTC-1 cells.

Arsenic poisoning and induced potential lesion is a global concern. However, the exact mechanisms underlying its toxicity especially in male reproductive system still remain unclear. Hence, this study aimed to explore the roles of mTOR and Beclin1-Vps34/PI3K complex during As-induced-toxicity using Rapamycin (mTOR inhibitor), Beclin1 siRNA and 3-methyladenine (3-MA, Vps34/PI3K inhibitor) in testicular stromal cells. For this, mouse testis Leydig Tumor Cell lines (MLTC-1) were challenged with As2O3 (0, 3, 6 and 9 µM) exposure for 24 hs. Lyso-Tracker Red and Monodansylcadaverine (MDC) staining results depicted a significant accumulation of autophagosomes in MLTC-1 cells exposed to arsenic. Meanwhile, arsenic treatment up-regulated autophagic markers including LC3, Atg7, Beclin1 and Vps34 expressions, mTOR downstream autophagy related genes and the Beclin1-Vps34/PI3K complex associated members. Furthermore, silencing of Beclin1, and inhibition of Vps34/PI3K and mTOR altered the arsenic-induced autophagosomes formation. However, p62, the substrate protein of autophagy, was also up-regulated by arsenic administration independent on Beclin1-Vps34/PI3K complex. Altogether, our results revealed that arsenic exposure induced autophagosomes formation via regulation of the Beclin1-Vps34/PI3K complex and mTOR pathway; the blockage of autophagosomes degradation maybe due to impaired function of lysosomes. Thus, this study provides a novel mechanistic approach with respect to As-induced male reproductive toxicity.