Fine particulate matter (PM2.5) induces testosterone disruption by triggering ferroptosis through SIRT1/HIF-1α signaling pathway in male mice.

Fine particulate matter (PM2.5), a significant component of air pollution particulate matter, is inevitable and closely associated with increasing male reproductive disorder. However, the testicular targets of PM2.5 and its toxicity related molecular mechanisms are still not fully understood. In this study, the conditional knockout (cKO) mice and primary Leydig cells were used to explore the testicular targets of PM2.5 and the related underlying mechanisms. First, apparent the structure impairment of seminiferous tubules, Leydig cells vacuolization, decline of serum testosterone and sperm quality reduction were found in male wild-type (WT) and Sirt1 knockout mice after exposure to PM2.5. Enrichment analyses revealed that differentially expressed genes (DEGs) were enriched in steroid hormone biosynthesis, ferroptosis, and HIF-1 signaling pathway in the mice testes after exposure to PM2.5, which were subsequently verified by the molecular biological analyses. Notably, similar enrichment analyses results were also observed in primary Leydig cells after treatment with PM2.5. In addition, Knockdown of Sirt1 significantly increased PM2.5-induced expression and activation of HIF-1α, which was in parallel to the changes of cellular iron levels, oxidative stress indicators and the ferroptosis markers. In conclusion, this highlights that PM2.5 triggers ferroptosis via SIRT1/HIF-1α signaling pathway to inhibit testosterone synthesis in males. These findings provide a novel research support for the study that PM2.5 causes male reproductive injury.

Exposure to Concentrated Ambient PM2.5 Compromises Spermatogenesis in a Mouse Model: Role of Suppression of Hypothalamus-Pituitary-Gonads Axis.

Epidemiological studies link ambient fine particulate matter (PM2.5) pollution to abnormalities in the male reproductive system. However, few toxicological studies have investigated this potentially important adverse effect of PM2.5 pollution. Therefore, in the present study, we analyzed the effects of PM2.5 exposure on spermatogenesis and hypothalamic-pituitary-gonadal (HPG) axis in a murine model. Fourteen male C57BL/6J mice were subjected to a 4-month exposure to filtered air or concentrated ambient PM2.5 (CAP). Their sperm count, testicular histology, spermatogenic parameters, and the major components of HPG axis were assessed. Exposure to CAP significantly reduced sperm count in the epididymis. This was accompanied by Sertoli cell vacuolization, immature germ cell dislocation, and decreases in pachytene spermatocytes and round spermatids of stage VII seminiferous tubules, suggesting a marked impairment of spermatogenesis in these mice. This impairment of spermatogenesis appeared to be attributable to a suppression of HPG axis subsequent to CAP exposure-induced hypothalamic inflammation, as exposure to CAP significantly increased TNFα and IL1b mRNA levels and meanwhile decreased gonadotropin-releasing hormone mRNA expression in the hypothalamus. Moreover, CAP exposure significantly reduced circulating testosterone and follicle-stimulating hormone, testicular testosterone and mRNA expression of follicle-stimulating hormone target gene SHBG and luteinizing hormone target genes P450scc, 17ßHSD, and StAR. The present data demonstrate that exposure to ambient PM2.5 impairs spermatogenesis in murine model, raising the concern over effects of ambient PM2.5 pollution on the male reproductive function.

Perfluorooctane sulfonate (PFOS) disrupts blood-testis barrier by down-regulating junction proteins via p38 MAPK/ATF2/MMP9 signaling pathway.

Perfluorooctane sulfonate (PFOS), an ubiquitous environmental pollutant, has been associated with male reproductive disorders. However, the underlying mechanisms are not yet fully understood. In this study, in vivo and in vitro models were used to explore the effects of PFOS on blood-testis barrier (BTB) and related molecular mechanisms. First, male ICR mice were orally administrated PFOS (0.5-10mg/kg/bw) for 4 weeks. Bodyweight, sperm count, BTB integrity and the expression of proteins including p38 mitogen-activated protein kinase (MAPK), activating transcription factor 2 (ATF2), matrix metalloproteinase 9 (MMP9), tissue inhibitor of metalloproteinase 1(TIMP1) and BTB related junction proteins were evaluated. Furthermore, mouse primary Sertoli cells were used to delineate the molecular mechanisms that mediate the effects of PFOS on BTB. Our results demonstrated that PFOS dose-dependently increased BTB permeability, p38/ATF2 phosphorylation and MMP9 expression, paralleled by decrease in BTB junction protein Occludin and Connexin43 expression. Additionally, similar to the in vivo results, treatment of PFOS time-dependently increased Sertoli cell-based BTB permeability, phosphorylated-p38/ATF2 level, translocation of ATF2 into the nucleus and MMP9 expression/activity, paralleled by decrease in Occludin and Connexin43 expression. Meanwhile, inhibition of p38 by SB203580, knockdown of ATF2, or inhibition of MMP9 was sufficient to reduce the effects of PFOS on the Sertoli cell BTB. As such, the present study highlights a role of the p38/ATF2/MMP9 signaling pathway in PFOS-induced BTB disruption, advancing our understanding of molecular mechanisms for PFOS-induced male reproductive disorders.