Perfluorooctanoic acid induces tight junction injury of Sertoli cells by blocking autophagic flux

Compound probiotics regulate the NRF2 antioxidant pathway to inhibit aflatoxin B1-induced autophagy in mouse Sertoli TM4 cells

This study investigated the effects of compound probiotics (CP) on AFB1-induced cytotoxicity in Sertoli TM4 cells. The L9 (3 × 3) orthogonal test was conducted to determine the optimal CP required for high AFB1 degradation in the artificial gastrointestinal fluid in vitro. The maximal AFB1 degradation rate was 40.55 % (P < 0.05) when the final viable count was 1.0 × 105 CFU/mL for Bacillus subtilis, Lactobacillus casein, and Saccharomyces cerevisiae. The effects of CP and the CP supernatant (CPS) on TM4 cell viability were evaluated to achieve the optimal protective conditions. When CPS4 (corresponding to CP viable counts of 1.0 × 104 CFU/mL) was added to the TM4 cells for 24 h, the cell viability reached 108.86 % (P < 0.05). AFB1 reduced TM4 cell viability in a concentration- and time-dependent manner at an AFB1 concentration ranging from 0 to 1.5 μM after 48-h AFB1 exposure. The optimal AFB1 concentration/times for low- and high damage models were 0.5 and 1.25 μM both for 24 h, which decreased viability to 76.04 % and 65.35 %, respectively. however, CPS4 added to low- and high-damage models increased the cell viability to 97.43 % and 75.12 %, respectively (P < 0.05). Transcriptome sequencing was performed based on the following designed groups: the control, 0.5 μM AFB1, 1.25 μM AFB1, CPS4, and CPS4+0.5 μM AFB1. The Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis was further performed to identify significantly enriched signaling pathways, which were subsequently verified. It was shown that AFB1 induced apoptosis by blocking the PI3K-AKT-mTOR pathway and upregulating autophagy proteins such as LC3B, Beclin1, and ATG5 while inhibiting autophagic flux. CPS4 promoted AFB1 degradation, activated the p62-NRF2 antioxidant, and inhibited ROS/TRPML1 pathways, thereby reducing ROS production and inflammation and ultimately alleviating AFB1-induced autophagy and apoptosis. These findings supports the potential of probiotics to protect the male reproductive system from toxin damage.

Perfluorooctanoic acid induces Leydig cell injury via inhibition of autophagosomes formation and activation of endoplasmic reticulum stress

Perfluorooctanoic acid (PFOA) is a man-made chemical broadly distributed in various ecological environment and human bodies, which poses potential health risks. Its toxicity, especially the male reproduction toxicity has drawn increasing attention due to declining birth rates in recent years. However, how PFOA induces male reproductive toxicity remains unclear. Here, we characterize PFOA-induced cell injury and reveal the underlying mechanism in mouse Leydig cells, which are critical to spermatogenesis in the testes. We show that PFOA induces cell injury as evidenced by reduced cell viability, cell morphology changes and apoptosis induction. RNA-sequencing analysis reveals that PFOA-induced cell injury is correlated with compromised autophagy and activated endoplasmic reticulum (ER) stress, two conserved biological processes required for regulating cellular homeostasis. Mechanistic analysis shows that PFOA inhibits autophagosomes formation, and activation of autophagy rescues PFOA-induced apoptosis. Additionally, PFOA activates ER stress, and pharmacological inhibition of ER stress attenuates PFOA-induced cell injury. Taken together, these results demonstrate that PFOA induces cell injury through inhibition of autophagosomes formation and induction of ER stress in Leydig cells. Thus, our study sheds light on the cellular mechanisms of PFOA-induced Leydig cell injury, which may be suggestive to human male reproductive health risk assessment and prevention from PFOA exposure-induced reproductive toxicity.

Inulin alleviates perfluorooctanoic acid-induced intestinal injury in mice by modulating the PI3K/AKT/mTOR signaling pathway

Perfluorooctanoic acid (PFOA) is a widely used industrial compound that has been found to induce intestinal toxicity. However, the underlying mechanisms have not been fully clarified and effective interventions are rarely developed. Inulin, a prebiotic, has been used as a supplement in human daily life as well as in gastrointestinal diseases and metabolic disorders. In this study, male mice were exposed to PFOA with or without inulin supplementation to investigate the enterotoxicity and potential intervention effects of inulin. Mice were administered PFOA at 1 mg/kg/day, PFOA with inulin at 5 g/kg/day, or Milli-Q water for 12 weeks. Histopathological analysis showed that PFOA caused colon shortening, goblet cell reduction, and inflammatory cell infiltration. The expression of the tight junction proteins ZO-1, occludin and claudin5 significantly decreased, indicating impaired barrier function. According to the RNA-sequencing analysis, PFOA exposure resulted in 917 differentially expressed genes, involving 39 significant pathways, such as TNF signaling and cell cycle pathways. In addition, the protein expression of TNF-α, IRG-47, cyclinB1, and cyclinB2 increased, while Gadd45γ, Lzip, and Jam2 decreased, suggesting the involvement of the TNF signaling pathway, cell cycle, and cell adhesion molecules in PFOA-associated intestinal injury. Inulin intervention alleviated PFOA-induced enterotoxicity by activating the PI3K/AKT/mTOR signaling pathway and increasing the protein expression of Wnt1, β-catenin, PI3K, Akt3, and p62, while suppressing MAP LC3β, TNF-α, and CyclinE expression. These findings suggested that PFOA-induced intestinal injury, including inflammation and tight junction disruption, was mitigated by inulin through modifying the PI3K/AKT/mTOR signaling pathways. Our study provides valuable insights into the enterotoxic effects of PFOA and highlights the potential therapeutic role of inulin.

Polystyrene nanoplastics aggravated dibutyl phthalate-induced blood-testis barrier dysfunction via suppressing autophagy in male mice

Nanoplastics (NPs) frequently cause adverse health effects by transporting organic pollutants such as dibutyl phthalate (DBP) into organisms by utilizing their large specific surface area, large surface charge, and increased hydrophobicity. However, the effects of NPs combined with DBP on the reproductive systems of mammals are still unclear. The present investigation involved the administration of polystyrene NPs (PS-NPs) to BALB/c mice via gavage, with a size of 100 nm and at doses of 5 mg/kg/day or 50 mg/kg/day, along with DBP at a dose of 0.5 mg/kg/day, or a combination of PS-NPs and DBP, for 30 days, to assess their potential for reproductive toxicity. The co-exposure of mice to PS-NPs and DBP resulted in a significant increase in reproductive toxicities compared to exposure to PS-NPs or DBP alone. This was demonstrated by a marked decrease in sperm quality, significant impairment of spermatogenesis, and increased disruption of the blood-testis barrier (BTB). Furthermore, a combination of in vivo and in vitro investigations were conducted to determine that the co-exposure of DBP and PS-NPs resulted in a noteworthy reduction in the expressions of tight junction proteins (ZO-1 and occludin). Moreover, the in vitro findings revealed that monobutyl phthalate (MBP, the active metabolite of DBP, 0.5 μg/mL) and PS-NPs (30 μg/mL or 300 μg/mL) inhibited autophagy in Sertoli cells, thereby increasing the expression of matrix metalloproteinases (MMPs). The study found that PS-NPs and DBP co-exposure caused harmful effects in male reproductive organs by disrupting BTB, which may be alleviated by reactivating autophagy. The paper's conclusions provided innovative perspectives on the collective toxicities of PS-NPs and other emerging pollutants.