Thyroid endocrine disruption and hepatotoxicity induced by bisphenol AF: Integrated zebrafish embryotoxicity test and deep learning

Different paths, same destination: Bisphenol A and its substitute induce the conjugative transfer of antibiotic resistance genes

Antibiotic resistance genes are primarily spread through horizontal gene transfer in aquatic environments. Bisphenols, which are widely used in industry, are pervasive contaminants in such environments. This study investigated how environmentally relevant concentrations of bisphenol A and its substitute (bisphenol S, Bisphenol AP and Bisphenol AF) affect the spread of antibiotic resistance genes among Escherichia coli. As a result, bisphenol A and its three substitutes were found to promote the RP4 plasmid-mediated conjugative transfer of antibiotic resistance genes with different promotive efficiency. Particularly, bisphenol A and bisphenol S were found to induce more than double the incidence of conjugation at 0.1 nmol/L concentration. They therefore were selected as model compounds to investigate the involved mechanisms. Surprisingly, both slightly inhibited bacterial activity, but there was no significant increase in cell death. Bisphenols exposure changed the polymeric substances excreted by the bacteria, increased the permeability of their cell membranes, induced the secretion of antioxidant enzymes and generated reactive oxygen species. They also affected the expression of genes related to conjugative transfer by upregulating replication and DNA transfer genes and downregulating global regulatory genes. It should be noted that gene expression levels were higher in the BPS-exposed group than in the BPA-exposed group. The synthesis of bacterial metabolites and functional components was also significantly affected by bisphenols exposure. This research has helped to clarify the potential health risks of bisphenol contamination of aquatic environments.

Interactions of Potential Endocrine-Disrupting Chemicals with Whole Human Proteome Predicted by AlphaFold2 Using an In Silico Approach

Binding with proteins is a critical molecular initiating event through which environmental pollutants exert toxic effects in humans. Previous studies have been limited by the availability of three-dimensional (3D) protein structures and have focused on only a small set of environmental contaminants. Using the highly accurate 3D protein structure predicted by AlphaFold2, this study explored over 60 million interactions obtained through molecular docking between 20,503 human proteins and 1251 potential endocrine-disrupting chemicals. A total of 66,613,773 docking results were obtained, 1.2% of which were considered to be high binding, as their docking scores were lower than -7. Monocyte to macrophage differentiation factor 2 (MMD2) was predicted to interact with the highest number of environmental pollutants (526), with polychlorinated biphenyls and polychlorinated dibenzofurans accounting for a significant proportion. Dimension reduction and clustering analysis revealed distinct protein profiles characterized by high binding affinities for perfluoroalkyl and polyfluoroalkyl substances (PFAS), phthalate-like chemicals, and other pollutants, consistent with their uniquely enriched pathways. Further structural analysis indicated that binding pockets with a high proportion of charged amino acid residues, relatively low α-helix content, and high β-sheet content were more likely to bind to PFAS than others. This study provides insights into the toxicity pathways of various pollutants impacting human health and offers novel perspectives for the establishment and expansion of adverse outcome pathway-based models.

Maternal bisphenols exposure and thyroid function in children: a systematic review and meta-analysis

Background

Evidence from animal experiments and epidemiological studies has reported controversial results about the effects of prenatal bisphenols (BPs) exposure on childhood thyroid function. This study aims to explore the associations of prenatal exposure to BPs with thyroid-related hormones (THs) in newborns and early childhood, with a particular focus on the sex-dependent and exposure level effects.

Methods

Correlated studies were systematically searched from PubMed, Web of Science, Medline, Cochrane, and Embase until February 21, 2024. The exposures assessed include bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and tetrachlorobisphenol A (TCBPA). THs measured were thyroid stimulating hormone (TSH), total tri-iodothyronine (TT3), total thyroxine (TT4), free tri-iothyronine (FT3), and free thyroxine (FT4). Effect estimates were quantified using coefficients from multivariable regression models. Statistical analyses were completed using Stata 16.0. The methodological quality of the included studies was evaluated using the Newcastle-Ottawa Scale (NOS).

Results

Eleven cohort studies comprising 5,363 children were included in our meta-analysis. Prenatal bisphenol concentrations were statistically significant related to alterations in thyroid hormones in children, exclusively in female offspring, including reduced TSH (β = -0.020, 95% CI: -0.036, -0.005) and increased TT3 levels (β = 0.011, 95% CI: 0.001, 0.021), and exposure to high concentration of bisphenols (>1.5 ug/g creatinine) significantly reduced FT3 levels in children (β = -0.011, 95% CI: -0.020, -0.003).

Conclusion

Prenatal bisphenol exposure is linked to alterations in thyroid hormone levels in girls, necessitating enhanced measures to control bisphenol exposure levels during pregnancy for child health protection.

Systematic Review Registration

https://inplasy.com, identifier INPLASY202450129.

Hepatotoxicity and lipid metabolism disorders of 8:2 polyfluoroalkyl phosphate diester in zebrafish: In vivo and in silico evidence

8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) has been shown to accumulate in the liver, but whether it induces hepatotoxicity and lipid metabolism disorders remains largely unknown. In this study, zebrafish embryos were exposed to 8:2 diPAP for 7 d. Hepatocellular hypertrophy and karyolysis were noted after exposure to 0.5 ng/L 8:2 diPAP, suggesting suppressed liver development. Compared to the water control, 8:2 diPAP led to significantly higher triglyceride and total cholesterol levels, but markedly lower levels of low-density lipoprotein, implying disturbed lipid homeostasis. The levels of two peroxisome proliferator activated receptor (PPAR) subtypes (pparα and pparγ) involved in hepatotoxicity and lipid metabolism were significantly upregulated by 8:2 diPAP, consistent with their overexpression as determined by immunohistochemistry. In silico results showed that 8:2 diPAP formed hydrogen bonds with PPARα and PPARγ. Among seven machine learning models, Adaptive Boosting performed the best in predicting the binding affinities of PPARα and PPARγ on the test set. The predicted binding affinity of 8:2 diPAP to PPARα (7.12) was higher than that to PPARγ (6.97) by Adaptive Boosting, which matched well with the experimental results. Our results revealed PPAR - mediated adverse effects of 8:2 diPAP on the liver and lipid metabolism of zebrafish larvae.

Frontier of toxicology studies in zebrafish model

Based on the 87 original publications only from quartiles 1 and 2 of Journal Citation Report (JCR) collected by the major academic databases (Science Direct, Web of Science, PubMed, and Wiley) in 2022, the frontier of toxicology studies in zebrafish model is summarized. Herewith, a total of six aspects is covered such as developmental, neurological, cardiovascular, hepatic, reproductive, and immunizing toxicities. The tested samples involve chemicals, drugs, new environmental pollutants, nanomaterials, and its derivatives, along with those related mechanisms. This report may provide a frontier focus benefit to researchers engaging in a zebrafish model for environment, medicine, food, and other fields.

The Joint Effects of Bisphenols and Iodine Exposure on Thyroid during Pregnancy

The aim of this research was to study the combined effects of bisphenols and iodine exposure on the thyroid gland during pregnancy. We included 162 pregnant women from a cohort established in Shanghai. Urinary concentrations of bisphenol A, bisphenol B(BPB), bisphenol C(BPC), bisphenol F, bisphenol S, and bisphenol AF(BPAF) were examined. Bayesian kernel machine regression (BKMR) and quantile g-computation models were used. The geometric means of BPA, BPB, BPC, BPF, BPS, BPAF, and ΣBPs levels in urine were 3.03, 0.24, 2.66, 0.36, 0.26, 0.72, and 7.55 μg/g creatinine, respectively. We observed a positive trend in the cumulative effects of BPs and iodine on serum triiodothyronine (FT3) and free thyroxine (FT4), as well as a U-shaped dose-response relationship between BPs and the probability of occurrence of thyroperoxidase autoantibody positivity in women with low urinary iodine concentration. In addition, a synergistic effect on the probability of occurrence of thyroid autoantibody positivity was observed between BPF and BPB, as well as between BPC and BPAF in this study. There were adverse health effects on the thyroid after co-exposure to BPs and iodine. Even if pregnant women were exposed to lower levels of BPs, women with iodine deficiency remained vulnerable to thyroid autoimmune disease.

Toxic effects of bisphenol AF on the embryonic development of marine medaka (Oryzias melastigma)

Bisphenol AF (BPAF), an emerging environmental endocrine disruptor, has been detected in surface waters worldwide and has adverse effects on aquatic organisms. The accumulation of BPAF in oceans and its potential toxic effect on marine organisms are important concerns. In this study, the effects of BPAF (10, 100, 1, and 5 mg/L) on marine medaka (Oryzias melastigma) were evaluated, including effects on the survival rate, heart rate, hatchability, morphology, and gene expression in embryos. The survival rate of marine medaka embryos was significantly lower after treatment with 5 mg/L BPAF than in the solvent control group. Exposure to 1 mg/L and 5 mg/L BPAF significantly reduced hatchability. Low-dose BPAF (10 μg/L) significantly accelerated the heart rate of embryos, while high-dose BPAF (5 mg/L) significantly decreased the heart rate. BPAF exposure also resulted in notochord curvature, pericardial edema, yolk sac cysts, cardiovascular bleeding, and caudal curvature in marine medaka. At the molecular level, BPAF exposure affected the transcript levels of genes involved in the thyroid system (dio1, dio3a, trhr2, tg, and thra), cardiovascular system (gata4, atp2a1, and cacna1da), nervous system (elavl3 and gap43), and antioxidant and inflammatory systems (sod, pparβ, and il-8) in embryos. These results indicate that BPAF exposure can alter the expression of functional genes, induce abnormal development, and reduce the hatching and survival rates in marine medaka embryos. Overall, BPAF can adversely affect the survival and development of marine medaka embryos, and BPAF may not be an ideal substitute for BPA.

Thyroid endocrine disruption induced by [C8mim]Br: An integrated in vivo, in vitro, and in silico study

Conventional thyroid-disrupting chemicals (TDCs) such as polybrominated diphenyl ethers, polychlorinated biphenyls, and bisphenols perturb animal's thyroid endocrine system by mimicking the action of endogenous thyroid hormones (THs), since they share a similar backbone structure of coupled benzene rings with THs. 1-methyl-3-octylimidazolium bromide ([C₈mim]Br), a commonly used ionic liquid (IL), has no structural similarity to THs. Whether it interferes with thyroid function and how its mode of action differs from conventional TDCs is largely unknown. Herein, zebrafish embryo-larvae experiments (in vivo), GH3 cell line studies (in vitro), and molecular simulation analyses (in silico) were carried out to explore the effect of [C₈mim]Br on thyroid homeostasis and its underlying mechanism. Molecular docking results suggested that [C₈mim]⁺ likely bound to retinoid X receptors (RXRs), which may compromise the formation of TH receptor/RXR heterodimers. This then perturbed the negative regulation of thyroid-stimulating hormone β (tshβ) transcription by T3 in GH3 cell line. The resulting enhancement of tshβ expression further caused hyperthyroidism and developmental toxicity in larval zebrafish. These findings provided a crucial aspect of the ecological risks of ILs, and presented a new insight into the thyroid-disrupting mechanisms for emerging pollutants that do not have structural similarity to THs.

Bisphenol AF induces multiple behavioral and biochemical changes in zebrafish (Danio rerio) at different life stages

As common environmental endocrine-disrupting chemicals (EDCs), bisphenol AF (BPAF) raises potential concerns for aquatic organisms due to its widespread presence and continued release in the aquatic environment. This research aimed to use zebrafish embryos and adult fish to explore the effects of environmentally relevant concentrations (5 μg/L), 50 μg/L and 500 μg/L of BPAF on zebrafish embryonic development, behavioral alterations, and the potential mechanisms driving these effects. The results showed that 500 μg/L of BPAF severely affected the growth and development of embryos. In behavioral experiments, all concentrations of BPAF significantly inhibited the locomotor activity of larvae, 50 and 500 μg/L BPAF significantly altered the anxiety-like and aggressive behavior of adult zebrafish. Furthermore, environmentally relevant concentrations and higher concentrations of BPAF induced varying degrees of oxidative stress in both embryonic and adult fish. The most significant histopathological changes and decreased acetylcholinesterase (AChE) activity were observed in the brain at 50 and 500 μg/L of BPAF. We hypothesized that oxidative stress is an important cause of behavioral disturbances in larvae and adult fish. To our best knowledge, the present experiment is a pioneer in studying the effects of BPAF on a variety of complex behaviors (swimming performance, anxiety-like, social behavior, aggression) in zebrafish, which emphasizes the potential health risk of higher concentrations of BPAF in terms of induced neurotoxicity.

Predicting bioconcentration factor and estrogen receptor bioactivity of bisphenol a and its analogues in adult zebrafish by directed message passing neural networks

The bioconcentration factor (BCF) is a key parameter for bioavailability assessment of environmental pollutants in regulatory frameworks. The comparative toxicology and mechanism of action of congeners are also of concern. However, there are limitations to acquire them by conducting field and laboratory experiments while machinelearning is emerging as a promising predictive tool to fill the gap. In this study, the Direct Message Passing Neural Network (DMPNN) was applied to predict logBCFs of bisphenol A (BPA) and its four analogues (bisphenol AF (BPAF), bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS)). For the test set, the Pearson correlation coefficient (PCC) and mean square error (MSE) were 0.85 and 0.52 respectively, suggesting a good predictive performance. The predicted logBCFs values by the DMPNN ranging from 0.35 (BPS) to 2.14 (BPAF) coincided well with those by the classical EPI Suite (BCFBAF model). Besides, estrogen receptor α (ERα) bioactivity of these bisphenols was also predicted well by the DMPNN, with a probability of 97.0 % (BPB) to 99.7 % (BPAF), which was validated by the extent of vitellogenin (VTG) induction in male zebrafish as a biomarker except BPS. Thus, with little need for expert knowledge, DMPNN is confirmed to be a useful tool to accurately predict logBCF and screen for estrogenic activity from molecular structures. Moreover, a gender difference was noted in the changes of three endpoints (logBCF, ER binding affinity and VTG levels), the rank order of which was BPAF > BPB > BPA > BPF > BPS consistently, and abnormal amino acid metabolism is featured as an omics signature of abnormal hormone protein expression.