Exposure to Benzo(a)pyrene damages mitochondrial function via suppressing mitochondrial melatonin receptors in ovarian corpus luteum during early pregnancy

BPDE induces ferroptosis in hippocampal neurons through ACSL3 suppression

Benzo(a)pyrene (B[a]P) and its ultimate active metabolite, benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), are known to have neurotoxic effects that can damage hippocampal neurons and cause cognitive impairments. Ferroptosis, a form of programmed cell death distinct from apoptosis, is associated with multiple neurodegenerative conditions. Recently, we have found that BPDE triggers ferroptosis in hippocampal neurons, though the underlying molecular mechanism remains unclear. Here, we firstly identified ACSL3 as the target of BPDE-induced ferroptosis through transcriptomics, and then investigated its role in ferroptosis using gene transfection technology in HT22 cells and primary hippocampal neurons. Our results showed that BPDE treatment caused significant transcriptional changes in HT22 cells, notably decreasing ACSL3 expression, which was further validated in both HT22 cells and primary hippocampal neurons. Furthermore, overexpression of ACSL3 effectively rescued the ferroptosis induced by BPDE in HT22 cells and primary mouse hippocampal neurons, characterized by increased cell viability, enhanced glutathione and glutathione peroxidase activities, and reduced levels of intracellular free Fe2+, reactive oxygen species, and malondialdehyde. In summary, our findings demonstrated that BPDE induces ferroptosis in hippocampal neurons by inhibiting ACSL3 expression, providing new insights into the toxicological mechanisms underlying BPDE-induced neurotoxicity.

Benzo(a)pyrene exposure during pregnancy leads to germ cell apoptosis in male mice offspring via affecting histone modifications and oxidative stress levels

Infertility has gradually become a global health concern, and evidence suggests that exposure to environmental endocrine-disrupting chemicals (EDCs) represent one of the key causes of infertility. Benzo(a)pyrene (BaP) is a typical EDC that is widespread in the environment. Previous studies have detected BaP in human urine, semen, cervical mucus, oocytes and follicular fluid, resulting in reduced fertility and irreversible reproductive damage. However, the mechanisms underlying the effects of gestational BaP exposure on offspring fertility in male mice have not been fully explored. In this study, pregnant mice were administered BaP at doses of 0, 5, 10 and 20 mg/kg/day via gavage from Days 7.5 to 12.5 of gestation. The results revealed that BaP exposure during pregnancy disrupted the structural integrity of testicular tissue, causing a disorganized arrangement of spermatogenic cells, compromised sperm quality, elevated levels of histone modifications and increased apoptosis in the testicular tissue of F1 male mice. Furthermore, oxidative stress was also increased in the testicular tissue of F1 male mice. BaP activated the AhR/ERα signaling pathway, affected H3K4me3 expression and induced apoptosis in testicular tissue. AhR and Cyp1a1 were overexpressed, and the expression of key molecules in the antioxidant pathway, including Keap1 and Nrf2, was reduced. The combined effects of these molecules led to apoptosis in testicular tissues, damaging and compromising sperm quality. This impairment in testicular cells further contributed to compromised testicular tissues, ultimately impacting the reproductive health of F1 male mice.

Benzopyrene represses mitochondrial fission factors and PINK1/Parkin-mediated mitophagy in primary astrocytes

Mitochondria are essential for various physiological functions in astrocytes in the brain, such as maintaining ion and pH homeostasis, regulating neurotransmission, and modulating neuroinflammation. Mitophagy, a form of autophagy specific to mitochondria, is essential for ensuring mitochondrial quality and function. Benzo[a]pyrene (BaP) accumulates in the brain, and exposure to it is recognized as an environmental risk factor for neurodegenerative diseases. However, while the toxic mechanisms of BaP have been investigated in neurons, their effects on astrocytes-the most prevalent glial cells in the brain-are not clearly understood. Therefore, this study aims to investigate the toxic effects of exposure to BaP on mitochondria in primary astrocytes. Fluorescent probes and genetically encoded indicators were utilized to visualize mitochondrial morphology and physiology, and regulatory factors involved in mitochondrial morphology and mitophagy were assessed. Additionally, the mitochondrial respiration rate was measured in BaP-exposed astrocytes. BaP exposure resulted in mitochondrial enlargement owing to the suppression of mitochondrial fission factors. Furthermore, BaP-exposed astrocytes demonstrated reduced mitophagy and exhibited aberrant mitochondrial function and physiology, such as altered mitochondrial respiration rates, increased mitochondrial superoxide, disrupted mitochondrial membrane potential, and dysregulated mitochondrial Ca2+. These findings offer insights into the underlying toxic mechanisms of BaP exposure in neurodegenerative diseases by inducing aberrant mitophagy and mitochondrial dysfunction in astrocytes.

Benzo[a]pyrene exposure disrupts the organelle distribution and function of mouse oocytes

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon compound that is generated during combustion processes, and is present in various substances such as foods, tobacco smoke, and burning emissions. BaP is extensively acknowledged as a highly carcinogenic substance to induce multiple forms of cancer, such as lung cancer, skin cancer, and stomach cancer. Recently it is shown to adversely affect the reproductive system. Nevertheless, the potential toxicity of BaP on oocyte quality remains unclear. In this study, we established a BaP exposure model via mouse oral gavage and found that BaP exposure resulted in a notable decrease in the ovarian weight, number of GV oocytes in ovarian, and oocyte maturation competence. BaP exposure caused ribosomal dysfunction, characterized by a decrease in the expression of RPS3 and HPG in oocytes. BaP exposure also caused abnormal distribution of the endoplasmic reticulum (ER) and induced ER stress, as indicated by increased expression of GRP78. Besides, the Golgi apparatus exhibited an abnormal localization pattern, which was confirmed by the GM130 localization. Disruption of vesicle transport processes was observed by the abnormal expression and localization of Rab10. Additionally, an enhanced lysosome and LC3 fluorescence intensity indicated the occurrence of protein degradation in oocytes. In summary, our results suggested that BaP exposure disrupted the distribution and functioning of organelles, consequently affecting the developmental competence of mouse oocytes.

Cell type-dependent response to benzo(a)pyrene exposure of human placental cell lines under normoxic, hypoxic, and pro-inflammatory conditions

Benzo(a)pyrene (BaP) can be detected in the human placenta. However, little is known about the effects of BaP exposure on different placental cells under various conditions. In this study, we aimed to investigate the effects of BaP on mitochondrial function, pyrin domain-containing protein 3 (NLRP3) inflammasome, and apoptosis in three human trophoblast cell lines under normoxia, hypoxia, and inflammatory conditions. JEG-3, BeWo, and HTR-8/SVneo cell lines were exposed to BaP under normoxia, hypoxia, or inflammatory conditions for 24 h. After treatment, we evaluated cell viability, apoptosis, aryl hydrocarbon receptor (AhR) protein and cytochrome P450 (CYP) gene expression, mitochondrial function, including mitochondrial DNA copy number (mtDNAcn), mitochondrial membrane potential (ΔΨm), intracellular adenosine triphosphate (iATP), and extracellular ATP (eATP), nitric oxide (NO), NLPR3 inflammasome proteins, and interleukin (IL)-1β. We found that BaP upregulated the expression of AhR or CYP genes to varying degrees in all three cell lines. Exposure to BaP alone increased ΔΨm in all cell lines but decreased NO in BeWo and HTR-8/SVneo, iATP in HTR-8/SVneo, and cell viability in JEG-3, without affecting apoptosis. Under hypoxic conditions, BaP did not increase the expression of AhR and CYP genes in JEG-3 cells but increased CYP gene expression in two others. Pro-inflammatory conditions did not affect the response of the 3 cell lines to BaP with respect to the expression of CYP genes and changes in the mitochondrial function and NLRP3 inflammasome proteins. In addition, in HTR-8/SVneo cells, BaP increased IL-1β secretion in the presence of hypoxia and poly(I:C). In conclusion, our results showed that BaP affected mitochondrial function in trophoblast cell lines by increasing ΔΨm. This increased ΔΨm may have rescued the trophoblast cells from activation of the NLRP3 inflammasome and apoptosis after BaP treatment. We also observed that different human trophoblast cell lines had cell type-dependent responses to BaP exposure under normoxia, hypoxia, or pro-inflammatory conditions.

FUNDC1-mediated mitophagy triggered by mitochondrial ROS is partially involved in 1-nitropyrene-evoked placental progesterone synthesis inhibition and intrauterine growth retardation in mice

Intrauterine growth retardation (IUGR) is a major cause of perinatal morbidity and mortality. Previous studies showed that 1-nitropyrene (1-NP), an atmospheric pollutant, induces placental dysfunction and IUGR, but the exact mechanisms remain uncertain. In this research, we aimed to explore the role of mitophagy on 1-NP-evoked placental progesterone (P4) synthesis inhibition and IUGR in a mouse model. As expected, P4 levels were decreased in 1-NP-exposed mouse placentas and maternal sera. Progesterone synthases, CYP11A1 and 3βHSD1, were correspondingly declined in 1-NP-exposed mouse placentas and JEG-3 cells. Mitophagy, as determined by LC3B-II elevation and TOM20 reduction, was evoked in 1-NP-exposed JEG-3 cells. Mdivi-1, a specific mitophagy inhibitor, relieved 1-NP-evoked downregulation of progesterone synthases in JEG-3 cells. Additional experiments showed that ULK1/FUNDC1 signaling was activated in 1-NP-exposed JEG-3 cells. ULK1 inhibitor or FUNDC1-targeted siRNA blocked 1-NP-induced mitophagy and progesterone synthase downregulation in JEG-3 cells. Further analysis found that mitochondrial reactive oxygen species (ROS) were increased and GCN2 was activated in 1-NP-exposed JEG-3 cells. GCN2iB, a selective GCN2 inhibitor, and MitoQ, a mitochondria-targeted antioxidant, attenuated GCN2 activation, FUNDC1-mediated mitophagy, and downregulation of progesterone synthases in JEG-3 cells. In vivo, gestational MitoQ supplement alleviated 1-NP-evoked reduction of placental P4 synthesis and IUGR. These results suggest that FUNDC1-mediated mitophagy triggered by mitochondrial ROS may contribute partially to 1-NP-induced placental P4 synthesis inhibition and IUGR.

The association between polycyclic aromatic hydrocarbons exposure and neuropsychiatric manifestations in perimenopausal women: A cross-sectional study

BACKGROUND

Increasing evidence shows that polycyclic aromatic hydrocarbons (PAHs) exposure may adversely affect human health. However, the links between combined exposure to PAHs and neuropsychiatric manifestations in perimenopausal women remain unclear.

METHODS

To explore these relationships further, we used the data from the National Health and Nutrition Examination Surveys (NHANES) of the 2005-2012 cycles. After filtering, five hundred forty-seven perimenopausal women aged 45-55 years were included in our analysis. Eight PAHs metabolites were measured to represent PAHs exposure in the body. In our study, depression, sleep disorders, and frequent mental distress (FMD) were used to describe the neuropsychiatric manifestations. Because of the bivariate correlations among PAHs compounds, principal component analysis (PCA) was conducted to achieve the dimension reduction process of PAHs compounds. To figure out if there is a relationship between urinary PAH metabolites and outcomes, multiple logistic regression, restricted cubic splines (RCS), and the Bayesian kernel machine regression (BKMR) were used.

RESULTS

The findings showed that urinary PAHs concentrations in a certain range were related to neuropsychiatric manifestations. In detail, the results of logistic regressions, RCS, and BKMR all indicated that urinary PAHs were positively correlated with depression. In addition, the results of principal components regression and RCS showed associations between urinary PAHs and the risk of FMD or sleep disorders, respectively.

CONCLUSIONS

Exposure to PAHs was linked to neuropsychiatric manifestations in perimenopausal women, but more pertinent researches are required to understand the connections fully.