AhR-mediated lipid peroxidation contributes to TCDD-induced cardiac defects in zebrafish

2,3,7,8-tetrachlorodibenzofuran modulates intestinal microbiota and tryptophan metabolism in mice

Persistent organic pollutants (POPs) are known to disrupt gut microbiota composition and host metabolism, primarily through dietary exposure. In this study, we investigate the impact of 2,3,7,8-tetrachlorodibenzofuran (TCDF) on gut microbiota and host metabolic processes. RNA-seq analysis revealed that TCDF exposure significantly affected tryptophan metabolism, lipid metabolic pathways, and immune system function. Metagenomic and metabolomic analyses further showed that TCDF reduced the abundance of Mucispirillum schaedleri and levels of two key tryptophan metabolites, indole-3-carboxaldehyde (3-IAld) and Indole acrylic acid (IA). Supplementation with 3-IAld and IA alleviated TCDF-induced liver toxicity in mouse, as evidenced by reduced Cyp1a1 expression, and mitigated intestinal inflammation, reflected by lower pro-inflammatory cytokines (Ifn-γ and Il-1β) in the colon. Additionally, 3-IAld and IA supplementation enhanced intestinal barrier function, as demonstrated by increased Mucin 2 (MUC2) expression in the gut mucosa of mouse. These findings suggest that TCDF exposure disrupts the gut microbiome and host metabolic balance, and highlight the potential therapeutic role of tryptophan-derived metabolites in mitigating environmental pollutant-induced damage.

The role of the ferroptosis pathway in the toxic mechanism of TCDD-induced liver damage in zebrafish

Dioxins, especially 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) are harmful environmental pollutants, which is known to accumulate in humans and animals through ingestion, drinking water, and direct contact, leading to severe liver steatosis and cell death. This study used zebrafish as an experimental model to explore whether TCDD affects the liver via the ferroptosis pathway. The study examined microscopic and ultrastructural characteristics, oxidative stress-related indicators, iron content, and related gene and protein expression in zebrafish larvae liver cells. The results showed that TCDD exposure led to a decrease in the number of hepatocytes in zebrafish larvae. However, pretreatment with the ferroptosis inhibitor ferrostatin-1 (fer-1) alleviated these TCDD-induced changes. The transmission electron microscopy showed that TCDD exposure led to mitochondrial damage in the liver cells, an elevated iron content, a decrease in the level of the ferroptosis-related enzyme glutathione, increased alanine aminotransferase and malondialdehyde enzyme activities, and decreased glutathione peroxidase 4 protein levels. These effects were alleviated by the fer-1 pretreatment. At the gene level, TCDD exposure induced the expression of ferroptosis-related genes (tf, tfr, tfr1b, and fpn), inflammatory factor-related genes (NF-kB, ptgs2a, and ptgs2b), and lipid degeneration and autophagy genes (atg5, ncoa4, and acox1), and inhibited the expression of oxidative stress-related genes (gpx4, slc7a11, and nrf2). The fer-1 pretreatment counteracted these gene expression changes induced by TCDD. These findings indicate that TCDD-induced liver fatty degeneration and cell death are closely related to the ferroptosis pathway.

Comprehensive three-dimensional microCT and signaling analysis reveal the teratogenic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on craniofacial bone development in mice

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in utero can result in osteogenic defect during palatogenesis, but the effects on other craniofacial bones and underlying mechanisms remain to be characterized. By treating pregnant mice with TCDD (40 μg/kg) at the vital craniofacial patterning stages (embryonic day 8.5, 10.5 and 12.5), and scanning and reconstructing the skulls at embryonic day 18.5 using microCT, we found that TCDD exposure at the earlier and later patterning stages induced variable craniofacial malformations, including premature fusion of metopic and coronal sutures, truncated palatal processes of maxillary and palatine bones, as well as opening oriented pterygoid processes. Further in vitro determination of the underlying mechanisms using human fetal palatal mesenchymal cells (hFPMCs) revealed that TCDD suppressed a wide variety of osteogenic genes responsible for osteoblast commitment and bone matrix synthesis and mineralization, through activating aryl hydrocarbon receptor (AhR) signaling and subsequently inhibiting estrogen signaling. The attenuation of AhR signaling significantly blocked the osteogenic toxicity, and partly restored the expressing level of estrogen receptor α (ERα). Additional treatment with ERα agonist (PPT) significantly relieved the activation of AhR and rescued the impairment of osteogenesis caused by TCDD. Together, our findings demonstrated that TCDD was teratogenic in numerous cranial neural crest cell-derived craniofacial bone development, and disrupted multiple genes for osteogenic differentiation via the TCDD-mediated AhR/ ERα signaling cross-talk.

The potential role of AhR/NR4A1 in androgen-dependent prostate cancer: focus on TCDD-induced ferroptosis

Prostate cancer (PCa) is a complex disease with diverse molecular alterations. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that exhibits pleiotropic roles in PCa, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a potent ligand for AhR. While targeting ferroptosis is an innovative PCa therapeutic strategy, the impact of AhR on this process remains unclear. This study aimed to investigate the influence of AhR on lipid peroxidation and ferroptosis. Results showed that TCDD activated AhR, as evidenced by increased CYP1A1 expression, leading to reduced cell viability. TCDD caused mitochondria shrinkage, decreased the GSH/GSSG ratio, and elevated the MDA levels and lipid peroxidation. Interestingly, AhR knockdown reversed these effects, similar to the action of ferroptosis inhibitors. Mechanistically, TCDD suppressed nuclear receptor subfamily 4 group A member 1 (NR4A1) expression, in part due to AhR activation. This suppression subsequently led to a reduction in the expression of the NR4A1 downstream target stearoyl-CoA desaturase 1 (SCD1). NR4A1 overexpression counteracted the effects of TCDD. In vivo, TCDD activated AhR, downregulated NR4A1 and SCD1 expression, induced mitochondria shrinkage, and increased the MDA and 4-hydroxynonenal (4-HNE) levels. In summary, TCDD promotes ferroptosis in androgen-dependent PCa via inhibiting the NR4A1/SCD1 axis, in part dependent on AhR activation.

Ferroptosis in diabetic cardiomyopathy: from its mechanisms to therapeutic strategies

Diabetic cardiomyopathy (DCM) is defined as structural and functional cardiac abnormalities in diabetes, and cardiomyocyte death is the terminal event of DCM. Ferroptosis is iron-dependent oxidative cell death. Evidence has indicated that iron overload and ferroptosis play important roles in the pathogenesis of DCM. Mitochondria, an important organelle in iron homeostasis and ROS production, play a crucial role in cardiomyocyte ferroptosis in diabetes. Studies have shown some anti-diabetic medicines, plant extracts, and ferroptosis inhibitors might improve DCM by alleviating ferroptosis. In this review, we systematically reviewed the evidence of ferroptosis in DCM. Anti-ferroptosis might be a promising therapeutic strategy for the treatment of DCM.

Therapeutic modulation of the kynurenine pathway in severe mental illness and comorbidities: A potential role for serotonergic psychedelics

Mounting evidence points towards a crucial role of the kynurenine pathway (KP) in the altered gut-brain axis (GBA) balance in severe mental illness (SMI, namely depression, bipolar disorder, and schizophrenia) and cardiometabolic comorbidities. Preliminary evidence shows that serotonergic psychedelics and their analogues may hold therapeutic potential in addressing the altered KP in the dysregulated GBA in SMI and comorbidities. In fact, aside from their effects on mood, psychedelics elicit therapeutic improvement in preclinical models of obesity, metabolic syndrome, and vascular inflammation, which are highly comorbid with SMI. Here, we review the literature on the therapeutic modulation of the KP in the dysregulated GBA in SMI and comorbidities, and the potential application of psychedelics to address the altered KP in the brain and systemic dysfunction underlying SMI and comorbidities. Psychedelics might therapeutically modulate the KP in the altered GBA in SMI and comorbidities either directly, via altering the metabolic pathway by influencing the rate-limiting enzymes of the KP and affecting the levels of available tryptophan, or indirectly, by affecting the gut microbiome, gut metabolome, metabolism, and the immune system. Despite promising preliminary evidence, the mechanisms and outcomes of the KP modulation with psychedelics in SMI and systemic comorbidities remain largely unknown and require further investigation. Several concerns are discussed surrounding the potential side effects of this approach in specific cohorts of individuals with SMI and systemic comorbidities.

(-)-Epicatechin gallate ameliorates cyprodinil-induced cardiac developmental defects through inhibiting aryl hydrocarbon receptor in zebrafish

BACKGROUND

Cyprodinil is a widely used fungicide with broad-spectrum activity, but it has been associated with cardiac abnormalities. (-)-Epicatechin gallate (ECG), a natural polyphenolic compound, has been shown to possess protective properties in cardiac development.

METHODS

In this study, we investigated whether ECG could mitigate cyprodinil-induced heart defects using zebrafish embryos as a model. Zebrafish embryos were exposed to cyprodinil with or without ECG.

RESULTS

Our results demonstrated that ECG significantly improved the survival rate, embryo movement, and hatching delay induced by cyprodinil. Furthermore, ECG effectively ameliorated cyprodinil-induced cardiac developmental toxicity, including pericardial anomaly and impairment of cardiac function. Mechanistically, ECG attenuated the cyprodinil-induced alterations in mRNA expression related to cardiac development, such as amhc, vmhc, tbx5, and gata4, as well as calcium ion channels, such as ncx1h, atp2a2a, and cdh2. Additionally, ECG was found to inhibit the activity of the aryl hydrocarbon receptor (AhR) signaling pathways induced by cyprodinil.

CONCLUSIONS

In conclusion, our findings provide evidence for the protective effects of ECG against cyprodinil-induced cardiac developmental toxicity, mediated through the inhibition of AhR activity. These findings contribute to a better understanding of the regulatory mechanisms and safe utilization of pesticide, such as cyprodinil.

The uses of zebrafish (Danio rerio) as an in vivo model for toxicological studies: A review based on bibliometrics

An in vivo model is necessary for toxicology. This review analyzed the uses of zebrafish (Danio rerio) in toxicology based on bibliometrics. Totally 56,816 publications about zebrafish from 2002 to 2023 were found in Web of Science Core Collection, with Toxicology as the top 6 among all disciplines. Accordingly, the bibliometric map reveals that "toxicity" has become a hot keyword. It further reveals that the most common exposure types include acute, chronic, and combined exposure. The toxicological effects include behavioral, intestinal, cardiovascular, hepatic, endocrine toxicity, neurotoxicity, immunotoxicity, genotoxicity, and reproductive and transgenerational toxicity. The mechanisms include oxidative stress, inflammation, autophagy, and dysbiosis of gut microbiota. The toxicants commonly evaluated by using zebrafish model include nanomaterials, arsenic, metals, bisphenol, and dioxin. Overall, zebrafish provide a unique and well-accepted model to investigate the toxicological effects and mechanisms. We also discussed the possible ways to address some of the limitations of zebrafish model, such as the combination of human organoids to avoid species differences.

Effects of exposure to 3,6-DBCZ on neurotoxicity and AhR pathway during early life stages of zebrafish (Danio rerio)

Polyhalogenated carbazoles (PHCZs) are emerging environmental pollutants, yet limited information is available on their embryotoxicity and neurotoxicity. Therefore, the current work was performed to investigate the adverse effects of 3,6-dibromocarbazole (3,6-DBCZ), a typical PHCZs homolog, on the early life stages of zebrafish larvae. It revealed that the 96-hour post-fertilization (hpf) median lethal concentration (LC50) value of 3,6-DBCZ in zebrafish larvae was determined to be 0.7988 mg/L. Besides, 3,6-DBCZ reduced survival rates at concentrations ≥ 1 mg/L and decreased hatching rates at ≥ 0.25 mg/L at 48 hpf. In behavior tests, it inhibited locomotor activities and reduced the frequency of recorded acceleration states in response to optesthesia (a sudden bright light stimulus) at concentrations ≥ 160 μg/L. Meanwhile, 3,6-DBCZ exposure decreased the frequency of recorded acceleration states in the startle response (tapping mode) at concentrations ≥ 6.4 μg/L. Pathologically, with the transgenic zebrafish model (hb9-eGFP), we observed a strikingly decreased axon length and number in motor neurons after 3,6-DBCZ treatment, which may be ascribed to the activation of the AhR signaling pathway, as evidenced by the molecular docking analysis and Microscale thermophoresis (MST) assay suggested that 3,6-DBCZ binding to AhR-ARNT2 compound proteins. Through interaction with AhR-ARNT, a striking reduction of the anti-oxidative stress (sod1/2, nqo1, nrf2) and neurodevelopment-related genes (elavl3, gfap, mbp, syn2a) were observed after 3,6-DBCZ challenge, accompanied by a marked increased inflammatory genes (TNFβ, IL1β, IL6). Collectively, our findings reveal a previously unrecognized adverse effect of 3,6-DBCZ on zebrafish neurodevelopment and locomotor behaviors, potentially mediated through the activation of the AhR pathway. Furthermore, it provides direct evidence for the toxic concentrations of 3,6-DBCZ and the potential target signaling in zebrafish larvae, which may be beneficial for the risk assessment of the aquatic ecosystems.

Protective effect of naringin against radiation-induced heart disease in rats via Sirt1/NF-κB signaling pathway and endoplasmic reticulum stress

This study was designed to explore the protective effect and mechanism of naringin (NG) on radiation-induced heart disease (RIHD) in rats. Rats were divided into four x-ray (XR) irradiation groups with different absorbed doses (0/10/15/20 Gy), or into three groups (control, XR, and XR + NG groups). Subsequently, the ultrasonic diagnostic apparatus was adopted to assess and compare the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular internal diameter at end diastole (LVIDd), and left ventricular internal diameter at end systole (LVIDs) in rats. Hematoxylin-eosin (H&E) staining and Masson staining were applied to detect the pathological damage and fibrosis of heart tissue. Western blot was used to measure the expression levels of myocardial fibrosis-related proteins, endoplasmic reticulum stress-related proteins, and Sirt1 (silent information regulator 1)/NF-κB (nuclear factor kappa-B) signaling pathway-related proteins in cardiac tissues. Additionally, enzyme-linked immunosorbent assay was utilized to detect the activities of pro-inflammatory cytokines, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) in cardiac tissue. The results showed that NG treatment significantly attenuated the 20 Gy XR-induced decline of LVEF and LVFS and the elevation of LVIDs. Cardiac tissue damage and fibrosis caused by 20 Gy XR were significant improved after NG treatment. Meanwhile, in rats irradiated by XR, marked downregulation was identified in the expressions of fibrosis-related proteins (Col I, collagen type I; α-SMA, α-smooth muscle actin; and TGF-β1, transforming growth factor-beta 1) and endoplasmic reticulum stress-related proteins (GRP78, glucose regulatory protein 78; CHOP, C/EBP homologous protein; ATF6, activating transcription factor 6; and caspase 12) after NG treatment. Moreover, NG treatment also inhibited the production of pro-inflammatory cytokines [interleukin-6, interleukin-1β, and monocyte chemoattractant protein-1 (MCP-1)], reduced the expression of MDA, and promoted the activities of SOD and CAT. Also, NG treatment promoted Sirt1 expression and inhibited p65 phosphorylation. Collectively, XR irradiation induced cardiac injury in rats in a dose-dependent manner. NG could improve the cardiac injury induced by XR irradiation by inhibiting endoplasmic reticulum stress and activating Sirt1/NF-κB signaling pathway.