AHR/ROS-mediated mitochondria apoptosis contributes to benzo[a]pyrene-induced heart defects and the protective effects of resveratrol

The resveratrol attenuates reactive oxygen species mediated DNA damage in cardiac malformations caused by 4-tert-octylphenol

4-tert-octylphenol (4-t-OP) is an alkylphenolic environmental endocrine disruptor extensively distributed in the environment, posing potential hazards to living organisms. Research has demonstrated that 4-t-OP induces cardiac injury and abnormalities in embryonic development, which can adversely affect heart development. The excessive production of reactive oxygen species (ROS) triggered by 4-t-OP may result in DNA damage. Hence, we hypothesized that ROS-mediated DNA damage plays a crucial role in abnormal cardiac development in zebrafish embryos exposed to 4-t-OP, while resveratrol (RSV), a common antioxidant found in natural foods, may provide protection. In this study, we exposed zebrafish embryos at 2 h post-fertilization (hpf) to various doses of 4-t-OP in combination with relevant inhibitor/agonist therapies. Using microscopy, we observed morphological alterations in the cardiac structure of zebrafish embryos at 72 hpf. The underlying molecular mechanisms were assessed through immunofluorescence, DCFH-DA probe, MitoSOX™ staining, Quantitative polymerase chain reaction, and other methods. Our findings revealed that 4-t-OP caused dose-dependent cardiac defects in zebrafish embryos. The overexpression of ROS/mitochondrial ROS (mtROS) induced by 4-t-OP was significantly reduced by the addition of RSV or the ROS inhibitor N-acetyl-L-cysteine (NAC). Furthermore, the inclusion of RSV or NAC significantly mitigated cardiac deformities, cardiac apoptosis, and DNA damage. Additionally, the apoptosis inhibitor Ac-DEVD-CHO and the Wnt/β-catenin agonist CHIR99021 decreased 4-t-OP-induced cardiac abnormalities. Moreover, the naturally occurring small molecule chemical RSV provided protection against 4-t-OP-induced heart developmental injury. This study elucidates the molecular mechanisms by which 4-t-OP induces oxidative stress, DNA damage, and cardiac defects in the heart of zebrafish larvae through the ROS/Wnt/β-catenin signaling pathway. These findings present novel molecular targets for the prevention and therapy of congenital heart disease, as well as enhance our understanding of the cardiotoxic effects of 4-t-OP.

Influence of CYP1A and AhR modulation on polycyclic aromatic hydrocarbon-induced developmental defects in Japanese medaka

Polycyclic aromatic hydrocarbons (PAHs) are known to induce developmental malformations in fish embryos. However, the interaction between aryl hydrocarbon receptor (AhR) and cytochrome P450 (CYP) in PAH-induced development defects remains unclear. Therefore, we investigated the effects of the CYP1A inhibitor piperonylbutoxide (PBO) and the AhR antagonist CH223191 (CH) on the development of Japanese medaka (Oryzias Latipes) embryos exposed to different PAHs. Japanese medaka embryos were exposed to three conditions: PAH alone, PAH and PBO, and PAH and CH. Microscopic observations were performed to examine the presence of developmental defects. Although neither phenanthrene (Phe) nor fluoranthene (Flu) induced morphological malformations in larvae, benzo(a)anthracene (BaA) exposure induced craniofacial deformities in the larvae. Additionally, BaA and PBO co-exposure significantly increased the rate and severity of malformations. Pyrene (Pyr) exposure induced craniofacial defects, cardiac hypertrophy, pericardial edema, and spinal curvature, which were attenuated by exposure to either CH or PBO. Collectively, these findings suggest that structurally different PAHs exert their toxic effects via distinct mechanisms during fish development.

Unraveling the Mechanisms of AhR-Notch Interplay in Mediating Arsenic Trioxide Cytotoxicity in MCF-7 and MDA-MB-231 Breast Cancer Cell Lines

Arsenic trioxide (ATO) induces oxidative stress and apoptotic cell death in cancer cells; however, the underlying mechanisms and its effects on other signaling pathways, particularly in breast cancer, remain inadequately understood. The aryl hydrocarbon receptor (AhR) is expressed in breast cancer cells and linked to disease progression, while Notch signaling enhances migratory properties in these cells. The simultaneous use of the AhR agonist (FICZ), AhR antagonist (CH223191), and Notch antagonist (DAPT) was intended to investigate how the modulation of these pathways affects the response of breast cancer cells (MDA-MB-231 and MCF-7 cell) to ATO. We measured cell viability, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and cell migration. Results show that ATO significantly reduces cell viability in a dose- and time-dependent manner, decreasing MMP and increasing ROS levels. Notably, co-exposure to ATO and CH223191 for 24 h enhanced cell viability, increased MMP, and diminished ROS compared to ATO alone. Also, the ATO + CH223191 + DAPT combination exhibited higher MMP and lower ROS levels than the ATO + FICZ + DAPT combination, indicating AhR inhibition's critical role in MMP regulation. Although ATO reduced migration compared to controls, adding DAPT or FICZ significantly increased migration percentages. Interestingly, co-exposure to CH223191 did not exhibit this effect and modulated the migratory effects of DAPT + ATO and FICZ + ATO combinations. In conclusion, these findings suggest that AhR stimulation via FICZ may enhance ATO's therapeutic effects, while simultaneous exposure to ATO, FICZ, and DAPT may lead to additive effects, reducing MMP and increasing ROS levels.

The Relationship Between Maternal Exposure to Endocrine-Disrupting Chemicals and the Incidence of Congenital Heart Diseases: A Systematic Review and Meta-Analysis

BACKGROUND

Congenital heart diseases are among the most common birth defects, significantly impacting infant health. Recent evidence suggests that exposure to endocrine-disrupting chemicals may contribute to the incidence of congenital heart diseases. This study systematically reviews and analyzes the association between maternal endocrine-disrupting chemicals exposure and congenital heart diseases.

METHODOLOGY

This systematic review and meta-analysis followed the Cochrane Handbook and PRISMA guidelines. We included studies assessing the link between maternal exposure to various endocrine-disrupting chemicals and the incidence of congenital heart diseases without restricting the study design or exposure assessment methods. Data were extracted from four databases, including PubMed, Scopus, Web of Science, and Cochrane Library, up to June 2024. Quality assessment of observational studies was conducted using the Newcastle-Ottawa Scale. Statistical analysis was performed using RevMan software version 5.3, presenting results as odds ratios with 95% confidence intervals.

RESULTS

Fifty-nine studies were included in the meta-analysis. The pooled analysis revealed a significant association between maternal endocrine-disrupting chemical exposure and the incidence of congenital heart diseases when measured using human samples (odds ratio = 1.63, 95% confidence interval [1.35-1.97], p < 0.00001). Notably, exposure to heavy metals, polycyclic aromatic hydrocarbons, and perfluoroalkyl compounds was strongly associated with congenital heart diseases. However, non-sample-based methods showed no significant overall correlation (odds ratio = 1.08, 95% confidence interval [0.93-1.26], p = 0.30), except for housing renovation compounds, which were linked to a higher incidence of congenital heart diseases.

CONCLUSIONS

Maternal exposure to specific endocrine-disrupting chemicals, particularly heavy metals and polycyclic aromatic hydrocarbons, significantly increases the risk of congenital heart diseases. These findings underscore the need for preventive measures to reduce endocrine-disrupting chemicals exposure during pregnancy and further research to elucidate the underlying mechanisms.

PFOS and PFOSA induce oxidative stress-mediated cardiac defects in zebrafish via PPARγ and AHR pathways, respectively

Perfluorooctane sulfonate (PFOS) and its precursor, perfluorooctane sulfonamide (PFOSA), are widespread in the environment. Evidence suggests a strong link between maternal exposure to PFOS/PFOSA and congenital heart diseases in the offspring, but the underlying mechanisms remain unclear. We hypothesized that PFOS and PFOSA induce cardiac defects through the peroxisome proliferator-activated receptor gamma (PPARγ) and aryl hydrocarbon receptor (AHR) pathways, respectively. In this study, we demonstrated that exposing zebrafish embryos to either PFOSA or PFOS caused cardiac malformations and dysfunction. Both PFOS and PFOSA induced reactive oxygen species (ROS) overproduction, mitochondrial damage, and apoptosis in zebrafish larvae hearts. Blockade of PPARγ through either pharmaceutical inhibition or genetic knockdown only attenuated the changes caused by PFOS, but not those elicited by PFOSA. Conversely, inhibition of AHR alleviated the adverse effects induced by PFOSA but not by PFOS. Both PFOSA and PFOS exhibited similar binding affinities to AHR using molecular docking techniques. The varying ability of PFOS and PFOSA to induce AHR activity in zebrafish embryonic hearts can be attributed to their different capabilities for activating PPARγ. In summary, our findings indicate that PFOS and PFOSA induce excessive ROS production in zebrafish larvae via the PPARγ and AHR pathways, respectively. This oxidative stress in turn causes mitochondrial damage and apoptosis, leading to cardiac defects.

Toxicity of antimony to plants: Effects on metabolism of N and S in a rice plant

Excess antimony (Sb) has been shown to damage plant growth. Rice plants readily absorb a large amount of Sb after a long period of flooding, yet the mechanisms underlying Sb toxicity in plants have not been solved. This study was conducted to explore the effects of Sb on the uptake of N and S, and monitor the concentrations of reduced glutathione (GSH) and enzymes associated with these processes. In addition, we analyzed differentially expressed metabolites (DEMs) correlated with amino acids (AAs) and oligopeptides, specifically DEMs containing sulfur (S), GSH and indole-3-acetic acid (IAA). The results showed that antimonite [Sb(III)] inhibited shoot growth whereas antimonate [Sb(V)] stimulated shoot growth. Interestingly, Sb(III)5/10 enhanced shoot concentrations of total nitrogen (N), NH4+-N [only at Sb(III)10] and S; but reduced the shoot concentrations of NO3-N and soluble protein. Sb(III)5/10 addition significantly increased oxidized glutathione (GSSG) concentration and activities of glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST) but non-significantly affected concentration of reduced glutathione (GSH) and activities of γ-glutamylcysteine synthetase (GCL) and glutathione reductase (GR), suggesting Sb(III) restricted GSH recycling. Addition of Sb (1) increased the abundance of DEMs associated with lignins, Ca uptake, toxicity/detoxification, and branched chain AAs; (2) decreased the abundance of AAs inclcuding isoleucine (Ile), leucine (Leu), tryptophan (Trp), tyrosine (Tyr) and histidine (His); (3) increased the abundance of arginine (Arg), putrescine (Put) and spermidine (Spd); and (4) affected methylation and acetylation of many AAs, especially acetylation.

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.

Synergy between nanoplastics and benzo[a]pyrene promotes senescence by aggravating ferroptosis and impairing mitochondria integrity in Caenorhabditis elegans

Micro-nano plastics have been reported as important carriers of polycyclic aromatic hydrocarbons (PAHs) for long-distance migration in the environment. However, the combined toxicity from long-term chronic exposure beyond the vehicle-release mechanism remains elusive. In this study, we investigated the synergistic action of Benzo[a]pyrene (BaP) and Polystyrene nanoparticles (PS) in Caenorhabditis elegans (C. elegans) as a combined exposure model with environmental concentrations. We found that the combined exposure to BaP and PS, as opposed to single exposures at low concentrations, significantly shortened the lifespan of C. elegans, leading to the occurrence of multiple senescence phenotypes. Multi-omics data indicated that the combined exposure to BaP and PS is associated with the disruption of glutathione homeostasis. Consequently, the accumulated reactive oxygen species (ROS) cannot be effectively cleared, which is highly correlated with mitochondrial dysfunction. Moreover, the increase in ROS promoted lipid peroxidation in C. elegans and downregulated Ferritin-1 (Ftn-1), resulting in ferroptosis and ultimately accelerating the aging process of C. elegans. Collectively, our study provides a new perspective to explain the long-term compound toxicity caused by BaP and PS at real-world exposure concentrations.

Aryl hydrocarbon receptor dynamics in esophageal squamous cell carcinoma: From immune modulation to therapeutic opportunities

Esophageal squamous cell carcinoma (ESCC) is a substantial global health burden. Immune escape mechanisms are important in ESCC progression, enabling cancer cells to escape the surveillance of the host immune system. One key player in this process is the Aryl Hydrocarbon Receptor (AhR), which influences multiple cellular processes, including proliferation, differentiation, metabolism, and immune regulation. Dysregulated AhR signaling participates in ESCC development by stimulating carcinogenesis, epithelial-mesenchymal transition, and immune escape. Targeting AhR signaling is a potential therapeutic approach for ESCC, with AhR ligands showing efficacy in preclinical studies. Additionally, modification of AhR ligands and combination therapies present new opportunities for therapeutic intervention. This review aims to address the knowledge gap related to the role of AhR signaling in ESCC pathogenesis and immune escape.

Studies on the characteristics of polycyclic aromatic hydrocarbons accumulation in lipids and the disturbance of lipid metabolism of Ruditapes philippinarum

Polycyclic aromatic hydrocarbons (PAHs) constitute a class of persistent organic pollutants with strong lipophilicity, which readily accumulate within organisms and have the effect to induce disorders in lipid metabolism. The present study aimed to investigate the accumulation localization and pattern of PAHs in Ruditapes philippinarum, and to reveal the association between PAHs and lipids metabolism. The 21-day exposure experiment was conducted using a mixture of phenanthrene, chrysene, and benzo[a]pyrene (the proportion is 1:1:1) at concentrations of 0.4 μg/L, 2 μg/L, and 10 μg/L. The tissue distribution of PAHs indicated that the digestive gland was the primary site of PAHs accumulation. Meanwhile, fluorescence colocalization suggested that PAHs primarily accumulated within the lipid droplets of digestive gland cells. This study further determined the transcriptomic and lipidomic profiles of the digestive gland to analyze the key genes involved in disrupted lipid metabolism and the major lipids affected. Lipidomic analysis identified the key differential metabolites as triglycerides (TGs). Furthermore, TGs were upregulated in the digestive gland had a total carbon atom number of 50-64 and a total number of 3-9 double bonds in the acyl side chains. Biochemical analysis experiments and oil red O stained frozen sections confirmed that the content of TGs steadily increased in various tissues during the experiment, leading to an elevated digestive gland index. Changes of lipid metabolism associated genes expression level also indicated that the synthesis of lipid in digestive gland were up-regulated while the decomposition was down-regulated. This study is the first to demonstrate the cellular localization of PAHs accumulation in bivalves and confirms the pattern of variation in TGs, providing new insights into the mechanisms of PAHs bioaccumulation and lipid metabolism disruption.

Synergistic Toxicity of Pollutant and Ultraviolet Exposure from a Mitochondrial Perspective

Ultraviolet (UV) exposure and atmospheric pollution are both independently implicated in skin diseases such as cancer and premature aging. UVA wavelengths, which penetrate in the deep layers of the skin dermis, exert their toxicity mainly through chromophore photosensitization reactions. Benzo[a]pyrene (BaP), the most abundant polycyclic aromatic hydrocarbon originating from the incomplete combustion of organic matter, could act as a chromophore and absorb UVA. We and other groups have previously shown that BaP and UVA synergize their toxicity in skin cells, which leads to important oxidation. Even if mitochondria alterations have been related to premature skin aging and other skin disorders, no studies have focused on the synergy between UV exposure and pollution on mitochondria. Our study aims to investigate the combined effect of UVA and BaP specifically on mitochondria in order to assess the effect on mitochondrial membranes and the consequences on mitochondrial activity. We show that BaP has a strong affinity for mitochondria and that this affinity leads to an important induction of lipid peroxidation and membrane disruption when exposed to UVA. Co-exposure to UVA and BaP synergizes their toxicity to negatively impact mitochondrial membrane potential, mitochondrial metabolism and the mitochondrial network. Altogether, our results highlight the implication of mitochondria in the synergistic toxicity of pollution and UV exposure and the potential of this toxicity on skin integrity.

Long-term exposure to aryl hydrocarbon receptor agonist neburon induces reproductive toxicity in male zebrafish (Danio rerio)

Neburon is a phenylurea herbicide that is widely used worldwide, but its toxicity is poorly studied. In our previous study, we found that neburon has strong aryl hydrocarbon receptor (AhR) agonist activity, but whether it causes reproductive toxicity is not clear. In the present study, zebrafish were conducted as a model organism to evaluate whether environmental concentrations of neburon (0.1, 1 and 10 µg/L) induce reproductive disorder in males. After exposure to neburon for 150 days from embryo to adult, that the average spawning egg number in high concentration group was 106.40, which was significantly lower than 193.00 in control group. This result was mainly due to the abnormal male reproductive behavior caused by abnormal transcription of genes associated with reproductive behavior in the brain, such as secretogranin-2a. The proportions of spermatozoa in the medium and high concentration groups were 82.40% and 83.84%, respectively, which were significantly lower than 89.45% in control group. This result was mainly caused by hormonal disturbances and an increased proportion of apoptotic cells. The hormonal disruption was due to the significant changes in the transcription levels of key genes in the hypothalamus-pituitary-gonadal axis following neburon treatment. Neburon treatment also significantly activated the AhR signaling pathway, causing oxidative stress damage and eventually leading to a significant increase in apoptosis in the exposed group. Together, these data filled the currently more vacant profile of neburon toxicity and might provide information to assess the ecotoxicity of neburon on male reproduction at environmentally relevant concentrations.

Food-Borne Polycyclic Aromatic Hydrocarbons and Circadian Disruption

Circadian disruption has been found to increase the risk of metabolic diseases, brain disorders, and cancer. The aryl hydrocarbon receptor (AhR), responsible for xenobiotic metabolism, is known to be activated by certain environmental stimuli, including polycyclic aromatic hydrocarbons (PAHs). Exposure to these stimuli may lead to diseases related to circadian disruption, with AhR activation suggested as a leading cause. Both the aryl hydrocarbon receptor nuclear translocator (ARNT) and aryl hydrocarbon receptor nuclear translocator-like (BMAL1) are class II basic helix-loop-helix/Per-ARNT-SIM (bHLH-PAS) proteins. These proteins form heterodimers with stimulated class I bHLH-PAS proteins, including circadian locomotor output cycles kaput (CLOCK) and AhR. Due to their sequential similarity, the overactivation of AhR by toxicants, such as PAHs, may lead to the formation of heterodimers with BMAL1, potentially causing circadian disruption. Dysregulation of BMAL1 can affect a wide range of metabolic genes, emphasizing its crucial roles. However, this issue has not been adequately addressed. Previous studies have reported that the inhibitory effects of phytochemicals on AhR activation can ameliorate diseases induced by environmental toxicants. Additionally, some phytochemicals have shown preventive effects on circadian misalignment. Therefore, this Review aims to explore potential strategies to prevent circadian disruption induced by food-borne toxicants, such as benzo[a]pyrene; to generate new ideas for future studies; and to highlight the importance of investigating these preventive strategies.

Colistin Induces Oxidative Stress and Apoptotic Cell Death through the Activation of the AhR/CYP1A1 Pathway in PC12 Cells

Colistin is commonly regarded as the "last-resort" antibiotic for combating life-threatening infections caused by multidrug-resistant (MDR) gram-negative bacteria. Neurotoxicity is a potential adverse event associated with colistin application in clinical settings, yet the exact molecular mechanisms remain unclear. This study examined the detrimental impact of colistin exposure on PC12 cells and the associated molecular mechanisms. Colistin treatment at concentrations of 0-400 μM decreased cell viability and induced apoptotic cell death in both time- and concentration-dependent manners. Exposure to colistin triggered the production of reactive oxygen species (ROS) and caused oxidative stress damage in PC12 cells. N-acetylcysteine (NAC) supplementation partially mitigated the cytotoxic and apoptotic outcomes of colistin. Evidence of mitochondrial dysfunction was observed through the dissipation of membrane potential. Additionally, colistin treatment upregulated the expression of AhR and CYP1A1 mRNAs in PC12 cells. Pharmacological inhibition of AhR (e.g., using α-naphthoflavone) or intervention with the CYP1A1 gene significantly decreased the production of ROS induced by colistin, subsequently lowering caspase activation and cell apoptosis. In conclusion, our findings demonstrate, for the first time, that the activation of the AhR/CYP1A1 pathway contributes partially to colistin-induced oxidative stress and apoptosis, offering insights into the cytotoxic effects of colistin.

The detoxification ability of sex-role reversed seahorses determines the sexual dimorphism in immune responses to benzo[a]pyrene exposure

Sexual dimorphism in immune responses is an essential factor in environmental adaptation. However, the mechanisms involved remain obscure owing to the scarcity of data from sex-role-reversed species in stressed conditions. Benzo[a]pyrene (BaP) is one of the most pervasive and carcinogenic organic pollutants in coastal environments. In this study, we evaluated the potential effects on renal immunotoxicity of the sex-role-reversed lined seahorse (Hippocampus erectus) toward environmental concentrations BaP exposure. Our results discovered the presence of different energy-immunity trade-off strategies adopted by female and male seahorses during BaP exposure. BaP induced more severe renal damage in female seahorses in a concentration-dependent manner. BaP biotransformation and detoxification in seahorses resemble those in mammals. Benzo[a]pyrene-7,8-dihydrodiol-9,10-oxide (BPDE) and 9-hydroxybenzo[a]pyrene (9-OH-BaP) formed DNA adducts and disrupted Ca2+ homeostasis may together attribute the renal immunotoxicity. Sexual dimorphisms in detoxification of both BPDE and 9-OH-BaP, and in regulation of Ca2+, autophagy and inflammation, mainly determined the extent of renal damage. Moreover, the mechanism of sex hormones regulated sexual dimorphism in immune responses needs to be further elucidated. Collectively, these findings contribute to the understanding of sexual dimorphism in the immunotoxicity induced by BaP exposure in seahorses, which may attribute to the dramatic decline in the biodiversity of the genus.

Dissecting the long-term neurobehavioral impact of embryonic benz[a]anthracene exposure on zebrafish: Social dysfunction and molecular pathway activation

Benz[a]anthracene (BaA), a prevalent environmental contaminant within the polycyclic aromatic hydrocarbon class, poses risks to both human health and aquatic ecosystems. The impact of BaA on neural development and subsequent social behavior patterns remains inadequately explored. In this investigation, we employed the zebrafish as a model to examine the persisting effects of BaA exposure on social behaviors across various developmental stages, from larvae, juveniles to adults, following embryonic exposure. Our findings indicate that BaA exposure during embryogenesis yields lasting neurobehavioral deficits into adulthood. Proteomic analysis highlights that BaA may impair neuro-immune crosstalk in zebrafish larvae. Remarkably, our proteomic data also hint at the activation of the aryl hydrocarbon receptor (AHR) and cytochrome P450 1A (CYP1A) pathway by BaA, leading to the hypothesis that this pathway may be implicated in the disruption of neuro-immune interactions, contributing to observable behavioral disruptions. In summary, our findings suggest that early exposure to BaA disrupts social behaviors, such as social ability and shoaling behaviors, from the larval stage through to maturity in zebrafish, potentially through the detrimental effects on neuro-immune processes mediated by the AHR-CYP1A pathway.

A tryptophan-derived uremic metabolite/Ahr/Pdk4 axis governs skeletal muscle mitochondrial energetics in chronic kidney disease

Chronic kidney disease (CKD) causes accumulation of uremic metabolites that negatively affect skeletal muscle. Tryptophan-derived uremic metabolites are agonists of the aryl hydrocarbon receptor (AHR), which has been shown to be activated in CKD. This study investigated the role of the AHR in skeletal muscle pathology of CKD. Compared with controls with normal kidney function, AHR-dependent gene expression (CYP1A1 and CYP1B1) was significantly upregulated in skeletal muscle of patients with CKD, and the magnitude of AHR activation was inversely correlated with mitochondrial respiration. In mice with CKD, muscle mitochondrial oxidative phosphorylation (OXPHOS) was markedly impaired and strongly correlated with the serum level of tryptophan-derived uremic metabolites and AHR activation. Muscle-specific deletion of the AHR substantially improved mitochondrial OXPHOS in male mice with the greatest uremic toxicity (CKD + probenecid) and abolished the relationship between uremic metabolites and OXPHOS. The uremic metabolite/AHR/mitochondrial axis in skeletal muscle was verified using muscle-specific AHR knockdown in C57BL/6J mice harboring a high-affinity AHR allele, as well as ectopic viral expression of constitutively active mutant AHR in mice with normal renal function. Notably, OXPHOS changes in AHRmKO mice were present only when mitochondria were fueled by carbohydrates. Further analyses revealed that AHR activation in mice led to significantly increased pyruvate dehydrogenase kinase 4 (Pdk4) expression and phosphorylation of pyruvate dehydrogenase enzyme. These findings establish a uremic metabolite/AHR/Pdk4 axis in skeletal muscle that governs mitochondrial deficits in carbohydrate oxidation during CKD.

Chronic aryl hydrocarbon receptor activity impairs muscle mitochondrial function with tobacco smoking

BACKGROUND

Accumulating evidence has demonstrated that chronic tobacco smoking directly contributes to skeletal muscle dysfunction independent of its pathological impact to the cardiorespiratory systems. The mechanisms underlying tobacco smoke toxicity in skeletal muscle are not fully resolved. In this study, the role of the aryl hydrocarbon receptor (AHR), a transcription factor known to be activated with tobacco smoke, was investigated.

METHODS

AHR related gene (mRNA) expression was quantified in skeletal muscle from adult controls and patients with chronic obstructive pulmonary disease (COPD), as well as mice with and without cigarette smoke exposure. Utilizing both skeletal muscle-specific AHR knockout mice exposed to chronic repeated (5 days per week for 16 weeks) cigarette smoke and skeletal muscle-specific expression of a constitutively active mutant AHR in healthy mice, a battery of assessments interrogating muscle size, contractile function, mitochondrial energetics, and RNA sequencing were employed.

RESULTS

Skeletal muscle from COPD patients (N = 79, age = 67.0 ± 8.4 years) had higher levels of AHR (P = 0.0451) and CYP1B1 (P < 0.0001) compared to healthy adult controls (N = 16, age = 66.5 ± 6.5 years). Mice exposed to cigarette smoke displayed higher expression of Ahr (P = 0.008), Cyp1b1 (P < 0.0001), and Cyp1a1 (P < 0.0001) in skeletal muscle compared to air controls. Cigarette smoke exposure was found to impair skeletal muscle mitochondrial oxidative phosphorylation by ~50% in littermate controls (Treatment effect, P < 0.001), which was attenuated by deletion of the AHR in muscle in male (P = 0.001), but not female, mice (P = 0.37), indicating there are sex-dependent pathological effects of smoking-induced AHR activation in skeletal muscle. Viral mediated expression of a constitutively active mutant AHR in the muscle of healthy mice recapitulated the effects of cigarette smoking by decreasing muscle mitochondrial oxidative phosphorylation by ~40% (P = 0.003).

CONCLUSIONS

These findings provide evidence linking chronic AHR activation secondary to cigarette smoke exposure to skeletal muscle bioenergetic deficits in male, but not female, mice. AHR activation is a likely contributor to the decline in muscle oxidative capacity observed in smokers and AHR antagonism may provide a therapeutic avenue aimed to improve muscle function in COPD.

hsa_circ_0008500 regulates Benzo(a)pyrene-loaded gypsum-induced inflammation and apoptosis in human bronchial epithelial cells via activation of Ahr/C-myc pathways

Polycyclic aromatic hydrocarbons (PAHs) are major organic pollutants attached to fine particulate matter in the atmosphere. They induce lung inflammation, asthma, and other lung diseases. Exploring the toxic mechanism of PAHs on lung epithelial cells may provide a theoretical basis for the prevention and treatment of respiratory diseases induced by PAHs. In our study, 16 human bronchial epithelial (16HBE) cells were exposed to different concentrations of gypsum dust, Benzo(a)pyrene (BaP), and BaP-loaded gypsum dust for 24 hours. Gypsum dust loaded with BaP significantly increased the cytotoxicity of 16HBE cells, enhanced the production of lactate dehydrogenase (LDH), interleukin-6 (IL-6) and interleukin-8 (IL-8), induced cell apoptosis, and upregulate the expression of hsa_circ_0008500 (circ_0008500). The mechanism was studied with a BaP-loaded gypsum dust concentration of 1.25 mg/mL. StemRegenin 1 (SR1) pretreat significantly reduced the release of LDH, IL-6, and IL-8 and decreased the protein levels of Ahr、XAP2, C-myc, and p53. Second-generation sequencing indicated that circ_0008500 was highly expressed after 16HBE induced by BaP-loaded gypsum dust. Functional experiments confirmed that circ_0008500 promoted the inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust by regulating the Ahr signaling pathway. Our study showed that fine particulate matter adsorption of BaP significantly increased the toxic effect of BaP on cells. By activating the Ahr/C-myc pathway, circ_0008500 promoted inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust.

Study on epigenotoxicity, sex hormone synthesis, and DNA damage of benzo[a]pyrene in the testis of male Ruditapes philippinarum

Research on the mechanisms of reproductive toxicity caused by persistent organic pollutants (POPs) in marine animals has received significant attention. One group of typical POPs, called polycyclic aromatic hydrocarbons (PAHs), has been found to cause various reproductive toxicities in aquatic organisms, including epigenotoxicity, reproductive endocrine disruption, DNA damage effects and other reproductive toxicity, thereby affecting gonadal development. Interestingly, male aquatic animals are more susceptible to the disturbance and toxicity of environmental pollutants. However, current studies primarily focus on vertebrates, leaving a large gap in our understanding of the reproductive toxicity and mechanisms of PAHs interference in marine invertebrates. In this study, male Ruditapes philippinarum was used as an experimental subject to investigate reproduction-related indexes in clams under the stress of benzo[a]pyrene (B[a]P) at different concentrations (0, 0.8, 4 and 20 μg/L) during the proliferative, growth, maturity, and spawning period. We analyzed the molecular mechanisms of reproductive toxicity caused by PAHs in marine bivalves, specifically epigenotoxicity, reproductive endocrine disruption, and gonadal damage-apoptotic effect. The results suggest that DNA methylation plays a crucial role in mediating B[a]P-induced reproductive toxicity in male R. philippinarum. B[a]P may affect sex hormone levels, impede spermatogenesis and testis development in clams, by inhibiting the steroid hormone synthesis pathway and downregulating genes critical for cell proliferation, testis development, and spermatid expulsion. Moreover, the spermatids of male R. philippinarum were severely impaired under the B[a]P stress, leading to reduced reproductive performance in the clams. These findings contribute to a better understanding of the reproductive toxicity response of male marine invertebrates to POPs stress.

The potential of aryl hydrocarbon receptor as receptors for metabolic changes in tumors

Cancer cells can alter their metabolism to meet energy and molecular requirements due to unfavorable environments with oxygen and nutritional deficiencies. Therefore, metabolic reprogramming is common in a tumor microenvironment (TME). Aryl hydrocarbon receptor (AhR) is a ligand-activated nuclear transcription factor, which can be activated by many exogenous and endogenous ligands. Multiple AhR ligands can be produced by both TME and tumor cells. By attaching to various ligands, AhR regulates cancer metabolic reprogramming by dysregulating various metabolic pathways, including glycolysis, lipid metabolism, and nucleotide metabolism. These regulated pathways greatly contribute to cancer cell growth, metastasis, and evading cancer therapies; however, the underlying mechanisms remain unclear. Herein, we review the relationship between TME and metabolism and describe the important role of AhR in cancer regulation. We also focus on recent findings to discuss the idea that AhR acts as a receptor for metabolic changes in tumors, which may provide new perspectives on the direction of AhR research in tumor metabolic reprogramming and future therapeutic interventions.

Crosstalk between aryl hydrocarbon receptor and Wnt/β-catenin signaling pathway: Possible culprit of di (2-ethylhexyl) phthalate-mediated cardiotoxicity in zebrafish larvae

Typical plasticizer di (2-ethylhexyl) phthalate (DEHP) has been demonstrated to induce cardiotoxicity in zebrafish, but the potential molecular mechanisms involved have not been fully elucidated. Aryl hydrocarbon receptor (AhR), an essential protein for inducing developmental abnormalities, has been demonstrated to be activated by DEHP in other species, but whether the AhR signaling pathway also contributes to DEHP-mediated cardiac developmental toxicity in zebrafish remains unclear. Firstly, molecular docking simulations initially confirmed the possibility that DEHP has AhR agonistic activity. To further confirm this conjecture, this work analyzed the changes of cardiac-related indexes in zebrafish stressed by DEHP at individual, protein, and gene levels. The results showed that DEHP mediated cardiac phenotypic developmental defects, increased CYP1A1 activity, and oxidative stress as well as significant changes in the expression levels of key proteins and genes of AhR, Wnt/β-catenin, and Nrf2-Keap1 signaling pathways. Notably, the addition of AhR inhibitors effectively alleviated the above negative effects, indicating that the AhR signaling pathway and its crosstalk with the Wnt/β-catenin signaling pathway is an essential pathway for DEHP-mediated cardiac developmental toxicity. Overall, this work enriches the molecular mechanism of DEHP-mediated cardiac developmental defects in zebrafish and provides a reliable biomarker for future environmental risk assessment of DEHP.

AHR-mediated DNA damage contributes to BaP-induced cardiac malformations in zebrafish

Benzo[a]pyrene (BaP) is a representative polycyclic aromatic hydrocarbon widely present in the environment. We previously reported that the aryl hydrocarbon receptor (AHR) mediates BaP-induced apoptosis and cardiac malformations in zebrafish embryos, but the underlying molecular mechanisms were unclear. Since BaP is a mutagenetic compound, we hypothesize that BaP induces apoptosis and heart defects via AHR-mediated DNA damage. In this study, zebrafish embryos were exposed to BaP at a concentration of 0.1 μM from 2 to 72 h post fertilization, either with or without inhibitors/agonists. AHR activity and levels of reactive oxygen species (ROS) were examined under a fluorescence microscope. mRNA expression levels were quantified by qPCR. DNA damage and apoptosis were detected by immunofluorescence. Our findings revealed that BaP exposure significantly increased BPDE-DNA adducts, mitochondrial damage, apoptosis and heart defects in zebrafish embryos. These effects were counteracted by inhibiting AHR/cyp1a1 using pharmaceutical inhibitors or genetic knockdown. Furthermore, we observed that spironolactone, an antagonist of nucleotide excision repair (NER), significantly enhanced BaP-induced BPDE-DNA adducts, mitochondrial damage, apoptosis and heart malformation rates. Conversely, SRT1720, a SIRT1 agonist, reduced the adverse effects of BaP. Supplementation with spironolactone also enhanced γ-H2AX signals in the heart of zebrafish embryos exposed to BaP. Additional experiments demonstrated that BaP suppressed the expression of SIRT1. We further established that AHR, when activated by BaP, directly inhibited SIRT1 transcription, leading to downregulation of XPC and XPA, which are essential NER genes involved in the recognition and verification steps of the NER process. Taken together, our results indicate that AHR mediates BaP-induced DNA damage in the heart of zebrafish embryos by inducing BPDE-DNA adduct formation via the AHR/Cyp1a1 signalling pathway, as well as suppressing NER via AHR-mediated inhibition of SIRT1.

SIRT1 slows the progression of lupus nephritis by regulating the NLRP3 inflammasome through ROS/TRPM2/Ca2+ channel

Systemic lupus erythematosus (SLE) is a chronic multisystem inflammatory disease associated with autoantibody formation. Lupus nephritis (LN) is one of the most severe organ manifestations of SLE. The inflammatory response is a key factor in kidney injury, and the NLRP3 inflammasome is frequently associated with the pathogenesis of LN. Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD +)-dependent histone deacetylase, is a promising therapeutic target for preventing renal injury. However, the mechanism of SIRT1 in LN remains unclear. Here, we aimed to investigate the mechanism by which SIRT inhibits the NLRP3 inflammasome to slow the progression of LN. We detected the expression of SIRT1 and the infiltration of macrophages in MRL/lpr mice; the results showed that the expression of SIRT1 was decreased, and the symptoms of lupus nephritis were relieved after the use of resveratrol, which upregulated SIRT1. In vitro studies showed that after lipopolysaccharide (LPS) stimulation, SIRT1 expression decreased, and the NLRP3 inflammasome was activated. Upregulation of SIRT1 inhibits NLRP3 inflammasome activation and assembly by interfering with two signalling pathways. First, SIRT1 affects NF-κB expression, transcription, and inflammatory cytokine expression. Second, SIRT1 modulates calcium influx induced by transient receptor potential channel M2 (TRPM2), which could be partly due to the inhibition of reactive oxygen species (ROS) production. Our findings suggest that upregulated SIRT1 inhibits the NLRP3 inflammasome to slow the progression of lupus nephritis by regulating NF-κB and ROS/TRPM2/Ca2+ channels. This study reveals a new anti-inflammatory mechanism of SIRT1, suggesting that SIRT1 may be a potential therapeutic target for the prevention of LN.

Differential Susceptibility to Benzo[a]pyrene Exposure during Gestation and Lactation in Mice with Genetic Variations in the Aryl Hydrocarbon Receptor and Cyp1 Genes

Polycyclic aromatic hydrocarbons are ubiquitous air pollutants, with additional widespread exposure in the diet. PAH exposure has been linked to adverse birth outcomes and long-term neurological consequences. To understand genetic differences that could affect susceptibility following developmental exposure to polycyclic aromatic hydrocarbons, we exposed mice with variations in the aryl hydrocarbon receptor and the three CYP1 enzymes from gestational day 10 (G10) to weaning at postnatal day 25 (P25). We found unexpectedly high neonatal lethality in high-affinity AhrbCyp1b1(-/-) knockout mice compared with all other genotypes. Over 60% of BaP-exposed pups died within their first 5 days of life. There was a significant effect of BaP on growth rates in surviving pups, with lower weights observed from P7 to P21. Again, AhrbCyp1b1(-/-) knockout mice were the most susceptible to growth retardation. Independent of treatment, this line of mice also had impaired development of the surface righting reflex. We used high-resolution mass spectrometry to measure BaP and metabolites in tissues from both dams and pups. We found the highest BaP levels in adipose from poor-affinity AhrdCyp1a2(-/-) dams and identified three major BaP metabolites (BaP-7-OH, BaP-9-OH, and BaP-4,5-diol), but our measurements were limited to a single time point. Future work is needed to understand BaP pharmacokinetics in the contexts of gestation and lactation and how differential metabolism leads to adverse developmental outcomes.

3,4-benzo[a]pyrene aggravates myocardial infarction injury by activating NLRP3-related pyroptosis through PINK1/Parkin-mitophagy-mPTP opening axis

BACKGROUND

Air pollution is an important and interventionable risk factor for cardiovascular disease. Air pollution exposure, even for a short-term exposure, is conspicuously relevant to increased risk of myocardial infarction (MI) mortality and clinical evidence has shown that air pollution particulate matter (PM) induces the aggravation of AMI. 3,4-benzo[a]pyrene (BaP), an extremely toxic polycyclic aromatic hydrocarbon (PAH) and a common component of PM, is listed as one of the main objects of environmental pollution monitoring. Both epidemiological and toxicological studies suggest that BaP exposure may be associated with cardiovascular disease. Since PM is significantly associated with the increased risk of MI mortality, and BaP is an important component of PM associated with cardiovascular disease, we intend to investigate the effect of BaP on MI models.

METHODS

The MI mouse model and the oxygen and glucose deprivation (OGD) H9C2 cell model were used to investigate the effect of BaP in MI injury. The involvement of mitophagy and pyroptosis in regulating deterioration of cardiac function and aggravation of MI injury induced by BaP was comprehensively evaluated.

RESULTS

Our study shows that BaP exacerbates MI injury in vivo and in vitro, a result based on BaP-induced NLRP3-related pyroptosis. In addition, BaP can inhibit PINK1/Parkin dependent mitophagy through the aryl hydrocarbon receptor (AhR), thus the mitochondrial permeability transition pore (mPTP) was induced to open.

CONCLUSION

Our results suggest a role for the BaP from air pollution in MI injury aggravation and reveal that BaP aggravates MI injury by activating NLRP3-related pyroptosis via the PINK1/Parkin-mitophagy-mPTP opening axis.

Activation of the Aryl Hydrocarbon Receptor in Muscle Exacerbates Ischemic Pathology in Chronic Kidney Disease

BACKGROUND

Chronic kidney disease (CKD) accelerates the development of atherosclerosis, decreases muscle function, and increases the risk of amputation or death in patients with peripheral artery disease (PAD). However, the mechanisms underlying this pathobiology are ill-defined. Recent work has indicated that tryptophan-derived uremic solutes, which are ligands for AHR (aryl hydrocarbon receptor), are associated with limb amputation in PAD. Herein, we examined the role of AHR activation in the myopathy of PAD and CKD.

METHODS

AHR-related gene expression was evaluated in skeletal muscle obtained from mice and human PAD patients with and without CKD. AHRmKO (skeletal muscle-specific AHR knockout) mice with and without CKD were subjected to femoral artery ligation, and a battery of assessments were performed to evaluate vascular, muscle, and mitochondrial health. Single-nuclei RNA sequencing was performed to explore intercellular communication. Expression of the constitutively active AHR was used to isolate the role of AHR in mice without CKD.

RESULTS

PAD patients and mice with CKD displayed significantly higher mRNA expression of classical AHR-dependent genes (Cyp1a1, Cyp1b1, and Aldh3a1) when compared with either muscle from the PAD condition with normal renal function (P<0.05 for all 3 genes) or nonischemic controls. AHRmKO significantly improved limb perfusion recovery and arteriogenesis, preserved vasculogenic paracrine signaling from myofibers, increased muscle mass and strength, as well as enhanced mitochondrial function in an experimental model of PAD/CKD. Moreover, viral-mediated skeletal muscle-specific expression of a constitutively active AHR in mice with normal kidney function exacerbated the ischemic myopathy evidenced by smaller muscle masses, reduced contractile function, histopathology, altered vasculogenic signaling, and lower mitochondrial respiratory function.

CONCLUSIONS

These findings establish AHR activation in muscle as a pivotal regulator of the ischemic limb pathology in CKD. Further, the totality of the results provides support for testing of clinical interventions that diminish AHR signaling in these conditions.

Dynamic changes of DNA methylation induced by benzo(a)pyrene in cancer

Benzo(a)pyrene (BaP), the earliest and most significant carcinogen among polycyclic aromatic hydrocarbons (PAHs), has been found in foods, tobacco smoke, and automobiles exhaust, etc. Exposure to BaP induced DNA damage directly, or oxidative stress-related damage, resulting in cell apoptosis and carcinogenesis in human respiratory system, digestive system, reproductive system, etc. Moreover, BaP triggered genome-wide epigenetic alterations by methylation, which might cause disturbances in regulation of gene expression, and thereby induced cancer. It has been proved that BaP reduced genome-wide DNA methylation, and activated proto-oncogene by hypomethylation in the promoter region, but silenced tumor suppressor genes by promoter hypermethylation, resulting in cancer initiation and progression. Here we summarized the changes in DNA methylation in BaP exposure, and revealed the methylation of DNA plays a role in cancer development.

Resveratrol Protects Rat Ovarian Luteinized Granulosa Cells from H2O2-Induced Dysfunction by Activating Autophagy

Resveratrol performs a variety of biological activities, including the potential regulation of autophagy. However, it is unclear whether resveratrol protects against luteal dysfunction and whether autophagy involves the regulation of resveratrol. This study aims to investigate whether resveratrol can regulate autophagy to resist H₂O₂-induced luteinized granulosa cell dysfunction in vitro. Our results showed that resveratrol can enhance cell viability, stimulate the secretion of progesterone and estradiol, and resist cell apoptosis in H₂O₂-induced luteinized granulosa cell dysfunction. Resveratrol can activate autophagy by stimulating the expression of autophagy-related genes at the transcriptional and translational levels and increasing the formation of autophagosomes and autophagolysosomes. Rapamycin, 3-methyladenine, and bafilomycin A1 regulated the levels of autophagy-related genes in H₂O₂-induced luteinized granulosa cell dysfunction and further confirmed the protective role of autophagy activated by resveratrol. In conclusion, resveratrol activates autophagy to resist H₂O₂-induced oxidative dysfunction, which is crucial for stabilizing the secretory function of luteinized granulosa cells and inhibiting apoptosis. This study may contribute to revealing the protective effects of resveratrol on resisting luteal dysfunction from the perspective of regulating autophagy.

Resveratrol inhibits AhR/Notch axis and reverses Th17/Treg imbalance in purpura by activating Foxp3

Background

Resveratrol has been reported to reverse the imbalance of T helper 17/regulatory T (Th17/Treg) by inhibiting the aryl hydrocarbon receptor pathway to treat immune thrombocytopenia. However, the regulation mechanism of the Notch signaling pathway by resveratrol has not been reported in purpura. This study is aimed to explore the mechanism of resveratrol ultrafine nanoemulsion (Res-mNE) in immune thrombocytopenia.

Methods

The immune thrombocytopenia mouse model was constructed to explore the effect of RES-mNE on immune thrombocytopenia. Cluster of differentiation 4 (CD4+) T cells were isolated and treated with different medications. CD4+ T cells were induced to differentiate into Th17 cells and Treg cells. Flow cytometry was used to detect the proportion of Th17 cells and Treg cells. The secretion was measured by the enzyme-linked immunosorbent assay (ELISA). Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blot were used to detect the mRNA and protein levels.

Results

Th17 cells, IL-17A and IL-22 increased in the immune thrombocytopenia mouse model, and the Treg cells and IL-10 decreased. Res-mNE promoted Treg cell differentiation and IL-10 secretion in CD4+ T cells while inhibiting Th17 cell differentiation and IL-17A and IL-22 levels. The AhR activator 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) reversed the effect of Res-mNE. Notch inhibitors reduced the ratio of Th17/Treg differentiation. Res-mNE activated the expression of Foxp3 by mediating AhR/Notch signaling to reverse the imbalance of Th17/Treg differentiation in immune thrombocytopenia.

Conclusion

Taken together, our findings demonstrated that RES-mNE inhibited the AhR/Notch axis and reversed Th17/Treg imbalance by activating Foxp3.

Wei-Tong-Xin ameliorated cisplatin-induced mitophagy and apoptosis in gastric antral mucosa by activating the Nrf2/HO-1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Wei-Tong-Xin (WTX) originated from the famous ancient Chinese formula "Wan Ying Yuan", recorded in the ancient Chinese medicine book "Zhong Zang Jing" by Hua Tuo. As "Jun" drugs, Dahuang and Muxiang have the effects of clearing heat and expelling fire, reducing food retention, regulating Qi and relieving pain. As "Chen" drug, Qianniuzi has the effect of assisting "Jun" drugs. Zhuyazao and Gancao, as "Zuo-Shi" drugs, can reduce toxicity and modulate the medicinal properties of other herbs.

AIM OF THE STUDY

The present study aimed to investigate the effect and mechanism of WTX on the oxidative stress of gastric antrum mucosa in mice with cisplatin (CIS)-induced dyspepsia.

MATERIALS

AND.

METHODS

A variety of experimental methods, including western blot, qRT-PCR, immunofluorescence and immunohistochemistry were performed in vivo and in vitro.

RESULTS

In vivo, WTX restored the number and function of interstitial cells of Cajal (ICCs), accompanied by the inhibition of lipid peroxidation. Moreover, WTX inhibited the activation of Parkin-dependent mitophagy and apoptosis. In vitro, WTX activated the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway and inactivated mitophagy in GES-1 cells. To explore the role of Nrf2 in WTX's improvement of CIS-induced cell damage, Nrf2 inhibitor ML385 was used in cell experiments. We found that ML385 counteracted the regulation of WTX on mitophagy and apoptosis. Finally, N-acetylcysteine (NAC), a reactive oxygen species (ROS) scavenger, was applied in our experiments, and the results suggested that WTX suppressed the CIS-induced apoptosis via mitochondrial pathway.

CONCLUSIONS

The above results, for the first time, indicated that WTX inhibited mitophagy and apoptosis of gastric antral mucosal cells induced by CIS through the Nrf2/HO-1 signaling pathway.

Chronic activation of the aryl hydrocarbon receptor in muscle exacerbates ischemic pathology in chronic kidney disease

Chronic kidney disease (CKD) accelerates the development of atherosclerosis, decreases muscle function, and increases the risk of amputation or death in patients with peripheral artery disease (PAD). However, the cellular and physiological mechanisms underlying this pathobiology are ill-defined. Recent work has indicated that tryptophan-derived uremic toxins, many of which are ligands for the aryl hydrocarbon receptor (AHR), are associated with adverse limb outcomes in PAD. We hypothesized that chronic AHR activation, driven by the accumulation of tryptophan-derived uremic metabolites, may mediate the myopathic condition in the presence of CKD and PAD. Both PAD patients with CKD and mice with CKD subjected to femoral artery ligation (FAL) displayed significantly higher mRNA expression of classical AHR-dependent genes ( Cyp1a1 , Cyp1b1 , and Aldh3a1 ) when compared to either muscle from the PAD condition with normal renal function ( P <0.05 for all three genes) or non-ischemic controls. Skeletal-muscle-specific AHR deletion in mice (AHR mKO ) significantly improved limb muscle perfusion recovery and arteriogenesis, preserved vasculogenic paracrine signaling from myofibers, increased muscle mass and contractile function, as well as enhanced mitochondrial oxidative phosphorylation and respiratory capacity in an experimental model of PAD/CKD. Moreover, viral-mediated skeletal muscle-specific expression of a constitutively active AHR in mice with normal kidney function exacerbated the ischemic myopathy evidenced by smaller muscle masses, reduced contractile function, histopathology, altered vasculogenic signaling, and lower mitochondrial respiratory function. These findings establish chronic AHR activation in muscle as a pivotal regulator of the ischemic limb pathology in PAD. Further, the totality of the results provide support for testing of clinical interventions that diminish AHR signaling in these conditions.

The Role of Mitochondria in Phytochemically Mediated Disease Amelioration

Mitochondrial dysfunction may cause cell death, which has recently emerged as a cancer prevention and treatment strategy mediated by chemotherapy drugs or phytochemicals. However, most existing drugs cannot target cancerous cells and may adversely affect normal cells via side effects. Mounting studies have revealed that phytochemicals such as resveratrol could ameliorate various diseases with dysfunctional or damaged mitochondria. For instance, resveratrol can regulate mitophagy, inhibit oxidative stress and preserve membrane potential, induce mitochondrial biogenesis, balance mitochondrial fusion and fission, and enhance the functionality of the electron transport chain. However, there are only a few studies suggesting that phytochemicals could potentially protect against the cytotoxicity of some current cancer drugs, especially those that damage mitochondria. Besides, COVID-19 and long COVID have also been reported to be correlated to mitochondrial dysfunction. Curcumin has been reported bringing a positive impact on COVID-19 and long COVID. Therefore, in this study, the benefits of resveratrol and curcumin to be applied for cancer treatment/prevention and disease amelioration were reviewed. Besides, this review also provides some perspectives on phytochemicals to be considered as a treatment adjuvant for COVID-19 and long COVID by targeting mitochondrial rescue. Hopefully, this review can provide new insight into disease treatment with phytochemicals targeting mitochondria.

Resveratrol ameliorates penconazole-induced cardiotoxicity by inhibition of oxidative stress and apoptosis in zebrafish larvae

Penconazole (PEN) is a typical systemic triazole fungicide with cardiac toxic effects. Resveratrol (RES) is a natural polyphenolic phytochemical with antioxidation properties. This study aimed to investigate if RES could protect against PEN-induced cardiotoxicity and to determine the underlying mechanisms. Zebrafish embryos were exposed to 0, 0.5, 1 and 2 mg/L of PEN from 4 to 96 h post fertilization (hpf) and cardiac developmental toxicity was assessed. Our results showed that PEN decreased hatching rate, survival rate, heart rate and body length, with increased malformation rate and spontaneous movement. PEN induced pericardial edema and abnormal cardiac structure in myl7:egfp transgenic zebrafish, as well as downregulation of cardiac development related genes (nkx2.5, tbx2.5, gata4, noto, and vmhc). In addition, PEN elevated oxidative stress via reactive oxygen species (ROS) accumulation and triggered cardiomyocytic apoptosis by upregulation of p53, bcl-2, bax and caspase 3. These adverse outcomes were counteracted by RES, indicating that RES ameliorated PEN-induced cardiotoxicity by inhibiting oxidative stress and apoptosis in zebrafish. Taken together, this study revealed the important role of oxidative stress in PEN-induced cardiotoxicity and identified dietary RES supplementation as a novel strategy to mitigate its toxicity.

Combined effects of microplastics and benz[a]anthracene on cardiotoxicity in zebrafish (Danio rerio) larvae: Size matters

The size of microplastics (MPs) plays an important role in combined toxic effects including synergistic or antagonistic effects. However, the influence of the size of MPs on the combined toxicity of contaminants remains unclear. In this study, we employed a zebrafish model to investigate the effects of MP size on the combined toxicity of benz[a]anthracene (BaA), a representative polyaromatic hydrocarbon, using three different sizes of polystyrene MPs (PSMPs) (0.2, 1.0, and 10 μm). Treatment of all groups did not result in any mortality of the zebrafish larvae. However, small-sized PSMPs (0.2 μm) enhanced the toxic effect of BaA in larvae such as cardiac defect and disruption of vessel formation. Medium-sized PSMPs (1.0 μm) were boundary in terms of the combined toxic effect; however, large-sized PSMPs (10 μm) alleviated the cardiotoxicity of BaA, including cardiac defect, ROS levels, and cell death. The combined effects showed a correlation with the body burden of MPs and BaA in larvae according to particle size (in the order of 0.2 μm > 1.0 μm > 10 μm). The synergistic effects occurred likely because the small PSMPs facilitated the body burden of BaA, induced excessive ROS by Ahr-mediated activity, and caused cell death in the heart, resulting in increased heart defects in the larvae. In contrast, large PSMPs abated the combined toxic effect through decreased body burden, whereas medium PSMPs form a boundary in combined effects. Therefore, the combined toxic effects of MPs are dependent on their size, which plays an important role in the transport and accumulation of environmental pollutants.

PM2.5 induces cardiac malformations via PI3K/akt2/mTORC1 signaling pathway in zebrafish larvae

Growing evidence indicates that maternal fine particulate matter (PM2.5) exposure is linked with congenital heart diseases in the offspring. To explore the underlying molecular mechanisms, we tested the effects of a number of pharmaceutical inhibitors, and found that suppressing the PI3K/akt signaling pathway had a protective effect against cardiac defects in zebrafish larvae exposed to extractable organic matter (EOM) from PM2.5. Using genetic knockdown and a specific akt2 pharmacological inhibitor, CCT128930, we demonstrated that akt2 activation is essential to EOM-induced heart malformations. Next, we found that the EOM-induced akt2 overactivation enhances intracellular reactive oxygen species (ROS)/mitochondrial ROS production, decreases mitochondrial membrane potential levels, and elicits intrinsic apoptosis in the heart of zebrafish embryos. In addition, EOM-induced akt2 activation decreased active β-catenin levels and inhibited the expression of Wnt target genes axin2 and nkx2.5. We further demonstrated that mTORC1 phosphorylation mediates the adverse effects of akt2 on intrinsic apoptosis and canonical Wnt signaling in the heart of zebrafish larvae exposed to EOM. Moreover, EOM-induced akt2 activation is mediated via aryl hydrocarbon receptor (AHR)/ROS-induced PTEN inhibition. In conclusion, our results indicate that PM2.5 activates PI3K/akt2/mTORC1 signaling via AHR/ROS-induced PTEN suppression, which leads to mitochondrial-mediated intrinsic apoptosis and Wnt signaling suppression, resulting in cardiac defects in zebrafish larvae.

PM2.5 induces mitochondrial dysfunction via AHR-mediated cyp1a1 overexpression during zebrafish heart development

Accumulating evidence suggests an association between maternal PM2.5 exposure and congenital heart diseases, but the underlying mechanisms remain unclear. We previously reported that PM2.5 induces cardiac malformations in zebrafish embryos via the aryl hydrocarbon receptor (AHR) pathway, which mediates the generation of reactive oxygen species (ROS). Since mitochondria are not only the main source of ROS but also sensitive to oxidative damage, we hypothesize that mitochondria may play an important role in the cardiac developmental toxicity of PM2.5. In this study, we demonstrated that extractable organic matter (EOM) from PM2.5 caused mitochondrial dysfunction in the heart of zebrafish embryos, including increased mitochondrial ROS (mtROS) levels, mitochondrial permeability transition pore (mPTP) opening, mitochondrial membrane potential (MMP) collapse, reduced mitochondrial ATP levels, and decreased expression levels of the mRNAs encoding mitochondrial proteins, which were attenuated by either pharmacological or genetic inhibition of AHR. We further demonstrated that improving mitochondrial function by inhibiting mPTP opening with Cyclosporin A suppressed the EOM-induced intracellular ROS and mtROS generation, MMP collapse, intrinsic apoptosis, and heart defects. Moreover, the EOM-induced mPTP opening was counteracted by inhibiting mtROS with mitoquinone mesylate (MitoQ). Supplementation with MitoQ also attenuated the EOM-induced mitochondrial dysfunction, apoptosis and heart defects. Additionally, knockdown of cyp1a1 but not cyp1b1 attenuated the EOM-induced mtROS generation and heart defects. Taken together, this study indicates that PM2.5 triggers mtROS generation via AHR-mediated cyp1a1 overexpression, which then causes mPTP opening and mitochondrial dysfunction, leading to apoptosis and heart defects.

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

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant that activates the aryl hydrocarbon receptor (AhR) pathway, has been reported to cause cardiac damage. However, the mechanism underlying AhR-induced cardiac defects in response to TCDD exposure remains unclear. In this study, we characterized the impacts of TCDD exposure on heart morphology and cardiac function in zebrafish. TCDD exposure in the early developmental stage of zebrafish embryos led to morphological heart malformation and pericardial edema, concomitant with reduced cardiac function. These cardiac defects were attenuated by inhibiting AhR activity with CH223191. Transcriptome profiling showed that, along with an upregulation of the AhR signaling pathway by TCDD treatment, the expression of pro-ferroptotic genes was upregulated, while that of genes implicated in glutathione metabolism were downregulated. Moreover, lipid peroxidation, as indicated by malonaldehyde (MDA) production, was increased in TCDD-exposed cardiac tissue. Accordingly, inhibiting lipid peroxidation with liproxstatin-1 reversed the adverse cardiac effects induced by TCDD treatment. Taken together, our findings demonstrate that AhR-mediated lipid peroxidation contributes to cardiac defects in the early developmental stage in zebrafish embryos exposed to TCDD.

Role of Aryl Hydrocarbon Receptor and Oxidative Stress in the Regioselective Toxicities of Hydroxychrysenes in Embryonic Japanese Medaka (Oryzias latipes)

Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are environmental contaminants that can be created through oxidation of parent PAHs. Previous studies have found that 2-hydroxychrysene (2-OHCHR) caused anemia in embryonic Japanese medaka whereas 6-hydroxychrysene (6-OHCHR) did not, an example of regioselective toxicity. Anemia was prevented by cytochrome P450 (CYP) inhibition, which reduced the formation of the potential oxidatively active metabolite, 1,2-catechol, from 2-OHCHR. 2-OHCHR has also been found to be a four-fold more potent aryl hydrocarbon receptor (AhR) agonist compared with 6-OHCHR. These findings led us to hypothesize that AhR activation and/or oxidative stress play an important role in 2-OHCHR toxicity. Although treatments with the AhR agonists polychlorinated biphenyl (PCB)126 and 2-methoxychrysene (2-MeOCHR) did not cause significant toxicity, pretreatments with the AhR antagonist, CH-223191, reduced anemia by 97.2 ± 0.84% and mortality by 96.6 ± 0.69%. Aryl hydrocarbon receptor inhibition by the antagonist was confirmed by significant reductions (91.0 ± 9.94%) in induced ethoxyresorufin-O-deethylase activity. Thiobarbituric acid reactive substances concentrations were 32.9 ± 3.56% higher (p < 0.05) in 2-OHCHR treatments at 100 hours postfertilization compared with controls. Staining 2-OHCHR-treated embryos with the reactive oxygen species (ROS) scavenger 2',7'-dichlorofluorescin diacetate revealed 32.6 ± 2.69% of 2-OHCHR-treated embryos exhibiting high concentrations of ROS in caudal tissues, which is a site for embryonic hematopoiesis in medaka. Pretreatment with antioxidants, N-acetylcysteine (NAC) or vitamin E (Vit E) significantly reduced 2-OHCHR-induced anemia (NAC: 80.7 ± 1.12% and Vit E: 99.1 ± 0.43%) and mortality (NAC: 67.1 ± 1.69% and Vit E: 98.9 ± 0.66%). These results indicate that AhR may mediate 2-OHCHR toxicity through canonical signaling by up-regulating CYP1, enhancing the formation of reactive metabolites of 2-OHCHR that generate ROS within caudal hematopoietic tissues, potentially disrupting hematopoiesis, leading to anemia and subsequent mortality. Environ Toxicol Chem 2023;42:698-706. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Abamectin causes cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death

This study aims to investigate the effects of environmentally relevant concentrations of abamectin on the cardiac function of carp and the potential mechanisms. Here, male carp were exposed to abamectin, and cardiac function-related enzymatic markers were examined. Cardiac histopathology, redox equilibrium, inflammation, and cell death were evaluated. Abamectin exposure caused cardiac dysfunction by upregulating lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK), creatine Kinase MB isoenzyme (CK-MB) and white blood cells (WBCs), and decreasing red blood cells (RBCs) and hemoglobin (Hb). DHE staining and biochemical assays revealed that abamectin caused ROS release and oxidative stress by inhibiting Nrf2-ARE pathway. Histopathological and real-time fluorescence quantitative PCR (RT-qPCR) assays revealed that abamectin caused myocardial fiber swelling and inflammatory cell infiltration, enhanced pro-inflammatory cytokines tumor necrosis factor-α (Tnf-α), interleukin-1 beta (Il-1β), and Il-6 levels and attenuated anti-inflammatory cytokines Il-10 and transforming growth factor beta 1 (Tgf-β1) through activating NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome and nuclear factor kappa-B (NF-κB) pathway. Tunel staining showed that abamectin triggered cardiac apoptosis via activating p53-mediated mitochondrial apoptosis with elevated bcl2-associated X (Bax), reduced B-cell lymphoma-2 (Bcl-2), and activated Caspase-9 and Caspase-3. Immunoblot analysis revealed that abamectin activated autophagic flow by inhibiting mammalian target of rapamycin (mTOR), resulting in the conversion of LC3B from LC3-I to LC3-II, elevation of autophagy protein 5 (Atg5), and reduction of p62. Overall, abamectin caused cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death.

Plantamajoside alleviates hypoxia-reoxygenation injury through integrin-linked kinase/c-Src/Akt and the mitochondrial apoptosis signaling pathways in H9c2 myocardial cells

Myocardial ischemia-reperfusion injury(MIRI) is one of the common complications after myocardial infarction surgery, Oxidative stress is among the main mechanisms of myocardial ischemia-reperfusion injury. Plantamajoside (PMS), the main effective ingredient in the genus Plantain, has been reported to possess an antioxidation, anti-inflammatory and anti-apoptosis role. However, whether PMS can attenuate myocardial ischemia-reperfusion injury is not yet known. Herein, we explored the effects of PMS on hypoxia-reoxygenation (H/R) injury in H9c2 cardiomyocytes and the underling molecular mechanisms of the treatment. Network pharmacological analysis screened the top 31 key genes in the treatment of MIRI disease treated with PMS, and the result of molecular docking further illustrated the roles that the PMS play in the treatment of MIRI through its interference with integrin-linked kinase (ILK) target protein. PMS was not cytotoxic in the concentration range of 5-40 μM and increased cell survival after H/R injury in a concentration-dependent manner without affecting proliferation or growth. PMS significantly reduced the levels of lactate dehydrogenase, malonic dialdehyde, reactive oxygen species and cell apoptosis, and increased soperoxide dismutase activity compared with those of the H/R injury group. PMS promoted the protein and mRNA expression of ILK and Bcl-2, the protein expression of p-Akt, and reduced the protein and mRNA expression of Bax, Caspase-3, and Cytochrome c, the protein expression of p-c-Src. PMS has protective effects against H/R injury in H9c2 cells, and its protective mechanism may be related to reactive oxygen species clearance, activation of the ILK/c-Src/Akt pathway and inhibition of the mitochondrial apoptosis.

Benzo(a)pyrene-induced mitochondrial respiration and glycolysis disturbance in human neuroblastoma cells

Mammalian cells generate ATP through mitochondrial respiration and glycolysis. Mitochondria not only play a key role in cell energy metabolism but also in cell cycle regulation. As a neurotoxic pollutant, benzo(a)pyrene (BaP) can trigger neuronal oxidative damage and apoptosis. However, the features of BaP-induced energy metabolism disturbance in SH-SY5Y cells has rarely been addressed. This study aimed to measure oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) as indications of respiratory activities and glycolytic. SH-SY5Y cells were treated with BaP to establish a cytotoxicity model, and butylated hydroxy anisole (BHA) was used to alleviate the damages induced by BaP. Using the Seahorse Extracellular Flux analyzer (XFp), we found that BaP significantly reduced basal respiration, ATP-linked OCR in SH-SY5Y cells with dose- and time-dependent. BHA supplementation recovered the mitochondrial respiration, synchronously attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers, then rescued BaP-induced cell apoptosis. But long-term exposure to BaP or exposure to a high dosage of BaP could decrease OCR associated with maximal respiratory, spare capacity, and glycolysis metabolism. At the same time, the damage to cells is also more severe with the rate of apoptosis and mitochondrial membrane potential (ΔΨm) loss rising sharply, which were not entirely reversed by BHA. This study provides energy metabolism-related, indicative biomarkers of cytotoxicity induced by BaP, which might provide information for early prevention and intervention.

Fine particulate matter induces heart defects via AHR/ROS-mediated endoplasmic reticulum stress

Accumulating body of evidence indicates that exposure to fine particulate matter (PM_2.5) is closely associated with congenital heart disease in the offspring, but the underlying molecular mechanisms remain to be elucidated. We previously reported that extractable organic matter (EOM) from PM_2.5 induces reactive oxygen species (ROS) overproduction by activating aromatic hydrocarbon receptor (AHR), leading to heart defects in zebrafish embryos. We hypothesized that endoplasmic reticulum (ER) stress might be elicited by the excessive ROS production and thereby contribute to the cardiac developmental toxicity of PM_2.5. In this study, we examined the effects of EOM on endoplasmic reticulum (ER) stress, apoptosis, and Wnt signal pathway in zebrafish embryos, and explored their roles in EOM-induced heart defects. Our results showed that 4-Phenylbutyric acid (4-PBA), a pharmaceutical inhibitor of ER stress, significantly attenuated the EOM-elevated heart malformation rates. Moreover, EOM upregulated the expression levels of ER stress marker genes including CHOP and PDI in the heart of zebrafish embryos, which were counteracted by genetic or pharmaceutical inhibition of AHR activity. The ROS scavenger N-Acetyl-l-cysteine (NAC) also abolished the EOM-induced ER stress. We further demonstrated that both 4-PBA and CHOP genetic knockdown rescued the PM_2.5-induced ROS overproduction, apoptosis and suppression of Wnt signaling. In conclusion, our results indicate that PM_2.5 induces AHR/ROS-mediated ER stress, which leads to apoptosis and Wnt signaling inhibition, ultimately resulting in heart defects.

Aryl hydrocarbon receptor: From pathogenesis to therapeutic targets in aging-related tissue fibrosis

Aging promotes chronic inflammation, which contributes to fibrosis and decreases organ function. Fibrosis, the excessive synthesis and deposition of extracellular matrix components, is the main cause of most chronic diseases including aging-related organ failure. Organ fibrosis in the heart, liver, and kidneys is the final manifestation of many chronic diseases. The aryl hydrocarbon receptor (AHR) is a cytoplasmic receptor and highly conserved transcription factor that is activated by a variety of small-molecule ligands to affect a wide array of tissue homeostasis functions. In recent years, mounting evidence has revealed that AHR plays an important role in multi-organ fibrosis initiation, progression, and therapy. In this review, we summarise the relationship between AHR and the pathogenesis of aging-related tissue fibrosis, and further discuss how AHR modulates tissue fibrosis by regulating transforming growth factor-β signalling, immune response, and mitochondrial function, which may offer novel targets for the prevention and treatment of this condition.

Synergistic protective effects of folic acid and resveratrol against fine particulate matter-induced heart malformations in zebrafish embryos

Ambient fine particulate matter (PM2.5) is a major environmental health problem worldwide, and recent studies indicate that maternal PM2.5 exposure is closely associated with congenital heart diseases (CHDs) in offspring. We previously found that supplementation with folic acid (FA) or Resveratrol (RSV) could protect against heart defects in zebrafish embryos exposed to extractable organic matter (EOM) from PM2.5 by targeting aryl hydrocarbon receptor (AHR) signaling and reactive oxygen species (ROS) production respectively. Thus, we hypothesized that FA combined with RSV may have a synergistic protective effect against PM2.5-induced heart defects. To test our hypothesis, we treated zebrafish embryos with EOM in the presence or absence of FA, RSV or a combination of both. We found that RSV and FA showed a clear synergistic protection against EOM-induced heart defects in zebrafish embryos. Further studies showed that FA and RSV suppressed EOM-induced AHR activity and ROS generation respectively. Although only RSV inhibited EOM-induced apoptosis, FA enhanced the inhibitory effect of RSV. Moreover, vitamin C (VC), a typical antioxidant, also exhibits a synergistic inhibitory effect with FA on EOM-induced apoptosis and heart defects. In conclusion, supplementation with FA and RSV have a synergistic protective effect against PM2.5-induced heart defects in zebrafish embryos by targeting AHR activity and ROS production respectively. Our results indicate that, in the presence of antioxidants, FA even at a low concentration level could protect against the high risk of CHDs caused by air pollution.

Mitochondrial Dysfunction as a Hallmark of Environmental Injury

Environmental factors including diet, sedentary lifestyle and exposure to pollutants largely influence human health throughout life. Cellular and molecular events triggered by an exposure to environmental pollutants are extremely variable and depend on the age, the chronicity and the doses of exposure. Only a fraction of all relevant mechanisms involved in the onset and progression of pathologies in response to toxicants has probably been identified. Mitochondria are central hubs of metabolic and cell signaling responsible for a large variety of biochemical processes, including oxidative stress, metabolite production, energy transduction, hormone synthesis, and apoptosis. Growing evidence highlights mitochondrial dysfunction as a major hallmark of environmental insults. Here, we present mitochondria as crucial organelles for healthy metabolic homeostasis and whose dysfunction induces critical adverse effects. Then, we review the multiple mechanisms of action of pollutants causing mitochondrial toxicity in link with chronic diseases. We propose the Aryl hydrocarbon Receptor (AhR) as a model of “exposome receptor”, whose activation by environmental pollutants leads to various toxic events through mitochondrial dysfunction. Finally, we provide some remarks related to mitotoxicity and risk assessment.