2,2',4,4'-Tetrabromodiphenyl ether exposure disrupts blood-testis barrier integrity through CMA-mediated ferroptosis

Role of ferroptosis mediated by abnormal membrane structure in DEHP-induced reproductive injury

Di-(2-ethylhexyl) phthalate (DEHP), a commonly used plasticizer, has been demonstrated to possess reproductive toxicity; however, the precise mechanisms underlying this effect have yet to be fully elucidated. This study aimed to investigate the potential mechanisms by which prepubertal DEHP exposure impairs testicular development and to provide possible therapeutic targets. We exposed BALB/c male mice from postnatal days 22-35 to different doses of DEHP (0, 250, and 500 mg/kg/day) and utilized lipid metabolomics and other methods to elucidate the reproductive damage caused by DEHP from a multidimensional tissue-cell-molecule perspective. Our findings indicate that DEHP exposure induces ferroptosis in testicular tissue by remodeling membrane lipid structure, in which the imbalance of phospholipid-polyunsaturated fatty acids (PL-PUFA) and phospholipid-monounsaturated fatty acids (PL-MUFA) playing a crucial role. DEHP exposure altered the expression of ACSL4 and MBOAT2 via HIPPO and androgen receptor pathways, thereby impacting PL-PUFA/PL-MUFA synthesis. In conclusion, this study highlights a link between DEHP-induced reproductive damage and lipid metabolism reprogramming, suggesting new targets for preventing DEHP-induced reproductive toxicity.

Interplay of Ferroptosis, Cuproptosis, Autophagy and Pyroptosis in Male Infertility: Molecular Crossroads and Therapeutic Opportunities

Male infertility is intricately linked to dysregulated cell death pathways, including ferroptosis, cuproptosis, pyroptosis, and autophagy. Ferroptosis, driven by iron-dependent lipid peroxidation through the Fenton reaction and inactivation of the GPX4/Nrf2/SLC7A11 axis, disrupts spermatogenesis under conditions of oxidative stress, environmental toxin exposure, or metabolic disorders. Similarly, cuproptosis-characterized by mitochondrial dysfunction and disulfide stress due to copper overload-exacerbates germ cell apoptosis via FDX1 activation and NADPH depletion. Pyroptosis, mediated by the NLRP3 inflammasome and gasdermin D, amplifies testicular inflammation and germ cell loss via IL-1β/IL-18 release, particularly in response to environmental insults. Autophagy maintains testicular homeostasis by clearing damaged organelles and proteins; however, its dysregulation impairs sperm maturation and compromises blood-testis barrier integrity. These pathways intersect through shared regulators; reactive oxygen species and mTOR modulate the autophagy-pyroptosis balance, while Nrf2 and FDX1 bridge ferroptosis-cuproptosis crosstalk. Therapeutic interventions targeting these mechanisms have shown promise in preclinical models. However, challenges persist, including the tissue-specific roles of gasdermin isoforms, off-target effects of pharmacological inhibitors, and transgenerational epigenetic impacts of environmental toxins. This review synthesizes current molecular insights into the cell death pathways implicated in male infertility, emphasizing their interplay and translational potential for restoring spermatogenic function.

Prepubertal Exposure to Tris(2-chloroethyl) Phosphate Disrupts Blood-Testis Barrier Integrity via Ferritinophagy-Mediated Ferroptosis

Tris(2-chloroethyl) phosphate (TCEP) is a representative chlorinated organophosphate flame retardant (OPFR) that demonstrates greater persistence than other non-halogenated alkyl or aryl OPFRs. Although TCEP has been shown to accumulate significantly in the environment and contribute to testicular toxicity and spermatogenic dysfunction, the precise underlying factors and mechanisms of action remain unclear. Herein, male ICR mice were gavaged with corn oil, 50 mg/kg body weight (bw) TCEP, or 100 mg/kg bw TCEP from postnatal day (PND) 22 to PND 35. TCEP exposure resulted in the disruption of blood-testis barrier (BTB) integrity and in abnormal testicular development. Considering that Sertoli cells constitute the primary target of toxicants and that TCEP induces oxidative stress in the testis and other organs, we focused on ferroptosis in Sertoli cells. Our findings revealed a significant increase in ferroptosis in the testes and Sertoli cells following TCEP exposure, and we observed functional restoration of Sertoli cell junctions upon treatment with the ferroptosis inhibitor ferrostatin-1. Furthermore, ferritin heavy chain 1 (FTH1) was markedly reduced in TCEP-exposed testes and Sertoli cells. Since nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy is essential for the degradation of FTH1, we assessed ferritinophagic activity and found significant upregulation of NCOA4, ATG5, ATG7, and LC3B II/I in TCEP-exposed testes and Sertoli cells. These results strongly suggest that TCEP triggers Sertoli cell ferroptosis by activating ferritinophagy that leads to reduced expression of BTB-associated proteins, ultimately causing BTB disruption and testicular developmental toxicity.

Benzyl butyl phthalate promotes ferroptosis in Sertoli cells via disrupting ceruloplasmin-mediated iron balance

Widespread environmental contamination with benzyl butyl phthalate (BBP) has raised concerns due to its high potential for bioaccumulation and male reproductive toxicity. However, the mechanisms underlying BBP-induced male reproductive damage remain unclear. As the adjacent Sertoli cell-formed blood-testis barrier (BTB) creates a privileged niche for spermatogenesis and may serve as the first target of reproductive toxicants, we mainly focused on the detrimental effect of BBP on Sertoli cells and the BTB in this study. C57BL/6 mice were administered BBP via oral gavage at doses ranging from 0 to 400 mg/kg/day for 60 consecutive days. A comprehensive investigation was performed to estimate testicular BBP levels, sperm parameters, histological alterations, functional permeability of the Sertoli cell-based BTB, and ferroptosis in mice. Isolated Sertoli cells were further used to explore and validate the role of ferroptosis in BBP-induced BTB disruption. The results showed that permeation of BBP into the testis induced reduction in sperm quantity and quality, accompanied by fractured BTB ultrastructure, compromised permeable 'fence' functions of BTB, decreased expressions of tight junction proteins (TJP1 and OCLN) and paracellular transepithelial electrical resistance (TER) of Sertoli cells. Moreover, BBP exposure significantly increased intracellular iron content, promoted lipid peroxidation, and activated ferroptosis in the testis of mice and primary Sertoli cells, which was involved in BBP-induced disruption of BTB integrity and function as confirmed by the ferroptosis inhibitors. In mechanism, BBP specifically downregulated the intracellular iron exporter ceruloplasmin (CP) level to inhibit Fe2+ export and the oxidization of Fe2+ into less toxic Fe3+, thus exacerbating ferroptosis in Sertoli cells. Overexpression of CP significantly suppressed ferroptosis and alleviated BBP-induced BTB disruption. These findings reveal the role of CP-mediated iron homeostasis in regulating Sertoli cell ferroptosis and BTB function, providing new insights into the mechanisms of BBP-related reproductive toxicity.

Perfluorohexane Sulfonic Acid Disrupts the Immune Microenvironment for Spermatogenesis by Damaging the Structure of the Blood-Testis Barrier in Mice

Perfluorohexane sulfonic acid (PFHxS) is extensively used in waterproof coatings and fire-fighting foams, and several studies have found it to be a potential health hazard, but there is still unknown about its effects on spermatogenesis. Our results showed that PFHxS-treated mice have significant reproductive toxicity, including a decrease in sperm count and motility, and the levels of sex hormones (P < 0.05). Concurrently, structural abnormalities are observed in sperm, affecting ≈60-75% of those in the PFHxS-treated group. Additionally, it is found that the structure of the blood-testis barrier (BTB) is damaged after PFHxS treatment, leading to higher expression levels of inflammatory cytokines in the microenvironment for spermatogenesis. Moreover, the expression of proteins associated with mitochondrial biogenesis, including PTEN-induced kinase 1 (PINK1) and NADPH oxidase 4 (NOX4), is dysregulated in the testes after PFHxS treatment. Based on metabolome data, the differential metabolite 3-hydroxybutanoic acid is identified in the PFHxS-treated group, which can regulate the histone Kac levels, especially H3K4ac and H3K9ac. In summary, the results of this study suggest that in the testes of PFHxS-treated mice, inflammatory factors disrupt the mitochondrial function and metabolic profiles and hinder the progress of gene transcription through histone Kac, ultimately causing sperm dysfunction.

The role of ferroptosis in environmental pollution-induced male reproductive system toxicity

This article provides a comprehensive review of the toxic effects of environmental pollution on the male reproductive system, with a particular emphasis on ferroptosis, a form of programmed cell death. Research has shown that environmental pollutants, such as heavy metals, pesticide residues, and plastic additives, can disrupt oxidative stress, increasing the production of reactive oxygen species (ROS) in germ cells. This disruption damages cellular lipids, proteins, and DNA, culminating in cell dysfunction or death. Ferroptosis, a cell death pathway closely linked to oxidative stress, is characterized by the accumulation of intracellular iron ions and elevated levels of lipid ROS. This review also explores the role of ferroptosis in male reproductive disorders, including its contributions to reduced sperm count, decreased motility, and abnormal morphology. Environmental pollutants, particularly heavy metals, can induce ferroptosis by interfering with intracellular antioxidant systems, notably the NRF2, GSH, and GPX4 pathways, accumulating toxic lipid peroxides. Furthermore, the article examines the potential interplay between ferroptosis and other forms of cell death, such as apoptosis, autophagy, pyroptosis, and necrosis, in the context of male reproductive health. The review underscores the critical need for further research into the link between environmental pollutants and male fertility, particularly focusing on ferroptosis. It advocates for targeted research efforts to mitigate the adverse effects of ferroptosis and protect reproductive health, emphasizing that a deeper understanding of these mechanisms could lead to innovative preventive strategies against environmental threats to fertility.