Polychlorinated Biphenyl Quinone Promotes Macrophage-Derived Foam Cell Formation

Impact of the environmental pollution on cardiovascular diseases: From epidemiological to molecular evidence

Environmental pollution poses a significant threat to human health, particularly concerning its impact on cardiovascular diseases (CVDs). This review synthesizes epidemiological and molecular evidence to elucidate the intricate relationship between environmental pollutants and CVDs. Epidemiological studies highlight the association between exposure to air, water, and soil pollutants and increased CVD risk, including hypertension, coronary artery disease, and stroke. Furthermore, molecular investigations unravel the underlying mechanisms linking pollutant exposure to CVD pathogenesis, such as oxidative stress, inflammation, endothelial dysfunction, and autonomic imbalance. Understanding these molecular pathways is crucial for developing targeted interventions and policy strategies to mitigate the adverse effects of environmental pollution on cardiovascular health. By integrating epidemiological and molecular evidence, this review provides insights into the complex interplay between environmental factors and CVDs, emphasizing the urgent need for comprehensive preventive measures and environmental policies to safeguard public health.

Inflammation and cardiometabolic diseases induced by persistent organic pollutants and nutritional interventions: Effects of multi-organ interactions

The development and outcome of inflammatory diseases are associated with genetic and lifestyle factors, which include chemical and nonchemical stressors. Persistent organic pollutants (POPs) are major groups of chemical stressors. For example, dioxin-like polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), and polybrominated diphenyl ethers (PBDEs) are closely associated with the incidence of inflammatory diseases. The pathology of environmental chemical-mediated inflammatory diseases is complex and may involve disturbances in multiple organs, including the gut, liver, brain, vascular tissues, and immune systems. Recent studies suggested that diet-derived nutrients (e.g., phytochemicals, vitamins, unsaturated fatty acids, dietary fibers) could modulate environmental insults and affect disease development, progression, and outcome. In this article, mechanisms of environmental pollutant-induced inflammation and cardiometabolic diseases are reviewed, focusing on multi-organ interplays and highlighting recent advances in nutritional strategies to improve the outcome of cardiometabolic diseases associated with environmental exposures. In addition, advanced system biology approaches are discussed, which present unique opportunities to unveil the complex interactions among multiple organs and to fuel the development of precision intervention strategies in exposed individuals.

Aryl hydrocarbon receptor: A bridge linking immuno-inflammation and metabolism in atherosclerosis

Cardiovascular disease is the leading cause of death worldwide, and atherosclerosis is a major contributor to this etiology. The ligand-activated transcription factor, known as the aryl hydrocarbon receptor (AhR), plays an essential role in the interactions between genes and the environment. In a number of human diseases, including atherosclerosis, the AhR signaling pathway has recently been shown to be aberrantly expressed and activated. It's reported that AhR can regulate the immuno-inflammatory response and metabolism pathways in atherosclerosis, potentially serving as a bridge that links these processes. In this review, we highlight the involvement of AhR in atherosclerosis. From the literature, we conclude that AhR is a potential target for controlling atherosclerosis through precise interventions.

Influence of e-waste exposure on DNA damage and DNA methylation in people living near recycling sites

The association between long-term exposure to e-waste and poor health is well established, but how e-waste exposure affects DNA methylation is understudied. In this study, we measured the DNA damage levels and the alternation of DNA methylation in peripheral blood mononuclear cells (PBMCs) collected from a population exposed to e-waste. The concentration of 28 PCB congeners in the blood samples of e-waste recycling workers was elevated than those of the reference group. DNA damage levels were significantly higher than that of samples from the reference group by detecting the SCGE, CA, and CBMN assays. Eventually, we found that the methylation level of 1233 gene loci was changed in the exposure group. Bioinformatic analysis of differential genes revealed that the hypermethylated genes were enriched in cell component movement and regulation of cell function, and hypomethylated genes were involved in the cellular metabolic process. Among the 30 genes we tested, 14 genes showed a negative correlation between methylation level and expression level. Therefore, e-waste exposure potentially increased the levels of DNA damage and alters DNA methylation, which would likely impact human health.

The redox activity of polychlorinated biphenyl quinone metabolite orchestrates its pro-atherosclerosis effect via CAV1 phosphorylation

Further investigations are required to prove that polychlorinated biphenyls (PCBs) exposure is a cardiovascular disease risk factor. Unlike previous studies that attributed the atherogenic effect of PCBs to aryl hydrocarbon receptor activation, we illustrated a new mechanism involved in the redox reactivity of PCBs. We discover the redox reactivity of quinone moiety is the primary factor for PCB29-pQ-induced proinflammatory response, which highly depends on the status of caveolin 1 (CAV1) phosphorylation. PCB29-pQ-mediated CAV1 phosphorylation disrupts endothelial nitric oxide synthase, toll-like receptor 4, and reduces interleukin-1 receptor-associated kinase 1 binding with CAV1. Phosphorylated proteomics analysis indicated that PCB29-pQ treatment significantly enriched phosphorylated peptides in protein binding functions, inflammation, and apoptosis signaling. Meanwhile, apolipoprotein E knockout (ApoE^-/-) mice exposed to PCB29-pQ had increased atherosclerotic plaques compared to the vehicle group, while this effect was significantly reduced in ApoE^-/-/CAV1^-/- double knockout mice. Thus, we hypothesis CAV1 is a platform for proinflammatory cascades induced by PCB29-pQ on atherosclerotic processes. Together, these findings confirm that the redox activity of PCB metabolite plays a role in the etiology of atherosclerosis.

d-ribose- l-cysteine abrogates testicular maladaptive responses induced by polychlorinated bisphenol intoxication in rats via activation of the mTOR signaling pathway mediating inhibition of apoptosis, inflammation, and oxidonitrergic flux

Male reproductive maladaptive responses are becoming a global health concern and also a social issue. Polychlorinated biphenyls (PCBs) are a member of halogenated aromatic environmental pollutants with diverse environmental matrices. This study was conducted to explore the mechanisms of PCBs-induced testicular maladaptive responses and the potential reversal effects of d-ribose- l-cysteine (DRLC) on testicular injury induced by administration of PCBs (2 mg/kg) for 30 days. DRLC (50 mg/kg) was administered orally for 15 days starting from Days 16 to 30 after the initial 15 days of treatment with PCB. All assays were carried out using established protocols. Administration of DRLC at 50 mg/kg after treatment with PCBs enhances body and testicular weights, gonadotropins (luteinizing hormone and follicle-stimulating hormone), testosterone and poor sperm quality. DRLC also reduced testicular injury score, improved spermatogenesis scoring, reduced oxidative stress biomarkers (malondialdehyde), as well as restored the reduced activities of antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase) and decreases pro-inflammatory response (tumor necrosis factor-alpha and NO). More so, DRLC treatment abrogates testicular DNA fragmentation and downregulated p53 and caspase 3 activities and upregulated the concentration of autophagy-related protein (mammalian target of rapamycin [mTOR] and Atg7). DRLC abates testicular deficit induced by PCBs intoxicated rats via activation of the mTOR signaling pathway mediating inhibition of apoptosis, Inflammation and oxidative flux.

Polychlorinated biphenyl quinone induces immunotoxicity via lymphocytes apoptosis and Th1-Th2 cell imbalance in C57BL/6 mice

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants distributed worldwide. Existing researches indicated that the immune system is one of the most sensitive indicators of adverse health effects caused by PCBs. We for the first time evaluated the immunotoxic effect of PCB29-pQ, an active quinone-type PCB metabolite. After PCB29-pQ exposure, the body weight of the mice was reduced, but increased the organ index of the spleen and lungs. The morphology and structure of the mouse spleen and lungs were changed, and partial types of lymphocyte subsets in the spleen were significantly reduced. The activation of caspase-3, the significant up-regulation of Bax and the decrease of Bcl-2 indicated occurrence of apoptosis. In addition, mRNA results showed that PCB29-pQ caused the imbalance of Th1/Th2 cytokines and promoted the Th1-type immune response. Taken together, the above results demonstrated that treatment with PCB29-pQ induced spleen immune dysfunction targeting the apoptosis pathway and Th1/Th2 cytokines imbalance in mice. Since the immune system plays a fundamental role in maintaining homeostasis and is strongly involved in the development of diseases, this study provides a new insight into the immunotoxicity mechanism of PCBs.

Tea polyphenols alleviates acetochlor-induced apoptosis and necroptosis via ROS/MAPK/NF-κB signaling in Ctenopharyngodon idellus kidney cells

Overuse of acetochlor pollutes soil and rivers, causing threats to the ecosystem. Studies found that acetochlor exposure could damage multiple organs and tissues in fish and mammal. Tea polyphenols (TP), a natural antioxidant that extracted from tea, has been widely used in food and feed additions. However, the mechanism by which acetochlor causes tissue damage is unclear, and its mitigating agent has yet to be developed. Therefore, we established acetochlor exposure and TP mitigation models by treating Ctenopharyngodon idellus kidney (CIK) cells with 20 μM acetochlor and/or 2.5 μg/mL TP for 24 h, and detected the programmed cell death and its related pathways. The results showed that acetochlor exposure modified antioxidant enzyme activities, induced oxidative stress, resulted in the decline of MMP and ATP levels, enhanced glycolysis and lactate accumulation, and triggered apoptosis and necroptosis in CIK cells. However, TP could inhibit CYP450s expression, activate Nrf2 pathway, enhance antioxidant capacity, further effectively alleviate acetochlor-induced CIK cell death. Overall, the present study proved that acetochlor exposure triggered mitochondrial damage and lactate accumulation-mediated apoptosis and necroptosis through CYP450s/ROS/MAPK/NF-κB pathway. Furthermore, TP could alleviate effectively cell death through relieving oxidative stress and lightening Warburg-like effect.

Bisphenol S exposure accelerates the progression of atherosclerosis in zebrafish embryo-larvae

Bisphenol S (BPS), widely utilized in manufacturing of daily necessities, is a toxicant with potential to induce atherosclerotic cardiovascular disease (ASCVD). However, the mode of action by which BPS exposure induces ASCVD remains unknown. Here, macrophages that were exposed to BPS in combination with oxidized low-density lipoprotein (oxLDL) exhibited enhanced formation of foam cells, a hallmark of ASCVD. Furthermore, zebrafish embryo-larvae were exposed to BPS (0, 1, 10 and 100 μg/L) for 15 days (d) and the characteristic symptoms of ASCVD including an inflammatory response, macrophage recruitment around blood vessels, and accumulation of oxLDL on vascular endothelium, were induced in 15-d larvae. After zebrafish were exposed to BPS for 45 d, BPS mobilized fatty acid metabolism and activated peroxisome proliferator-activated receptor signaling in larval liver, the hub of endogenous lipid metabolism, causing an increase in plasma LDL. Driven by high plasma LDL levels, the caudal artery of zebrafish larvae exhibited lipid accumulation and a thickened area with a large number of collagen fibers, accompanied by characteristic lesions, as well as hyperlipidemia, erythrocyte aggregation, thinner blood vessel walls and increased levels of leukocytes and thromboocytes in plasma. Our data demonstrate that BPS accelerates the progression of ASCVD using zebrafish embryo-larvae as a model.

Polychlorinated Biphenyl Quinone Metabolites Cause Neutrophil Extracellular Traps in Mouse Bone Marrow Neutrophils

Polychlorinated biphenyls (PCBs) are a group of persistent organic environmental pollutants with various toxic effects. Our previous research found that a highly reactive quinone metabolite of PCBs, namely, PCB29-pQ, causes excessive reactive oxygen species (ROS) production and different toxic actions. Neutrophil extracellular traps (NETs), the product of NETosis, are one of the newly discovered programmed cell deaths. Recent studies have suggested the association of NET formation with excess ROS. The objective of this study was to investigate the influence of PCB29-pQ exposure on NETs and its possible molecular mechanisms. Using scanning electron microscopy, immunofluorescence microscopy, and the quantitative analysis of extracellular DNA, we found that PCB29-pQ exposure induces the formation of NETs in mouse bone marrow. Mechanistically, our results suggested that PCB29-pQ induces histone citrullination and chromatin decondensation, which are necessary processes for NET formation. Moreover, PCB29-pQ exposure increases ROS and autophagy levels, while ROS and autophagy inhibitors significantly reverse NET formation. These results indicated that PCB29-pQ-induced NET formation was mediated by the intracellular ROS level and autophagy signaling. In general, our research uncovered a toxicity mechanism of PCB29-pQ, which suggested the necessity of evaluating its immunotoxicity during the risk assessment of PCB exposure.

Receptor Interacting Protein Kinases 1/3: The Potential Therapeutic Target for Cardiovascular Inflammatory Diseases

The receptor interacting protein kinases 1/3 (RIPK1/3) have emerged as the key mediators in cell death pathways and inflammatory signaling, whose ubiquitination, phosphorylation, and inhibition could regulate the necroptosis and apoptosis effectually. Recently, more and more studies show great interest in the mechanisms and the regulator of RIPK1/3-mediated inflammatory response and in the physiopathogenesis of cardiovascular diseases. The crosstalk of autophagy and necroptosis in cardiomyocyte death is a nonnegligible conversation of cell death. We elaborated on RIPK1/3-mediated necroptosis, pathways involved, the latest regulatory molecules and therapeutic targets in terms of ischemia reperfusion, myocardial remodeling, myocarditis, atherosclerosis, abdominal aortic aneurysm, and cardiovascular transplantation, etc.

Chlorpyrifos caused necroptosis via MAPK/NF-κB/TNF-α pathway in common carp (Cyprinus carpio L.) gills

Chlorpyrifos (CPF) is an organophosphate insecticide and can cause cell death of animals. In the study, the common carp were exposed to CPF at 0 μg/L (the control group), 1.16 μg/L (the low dose group), 11.6 μg/L (the medium dose group), and 116 μg/L (the high dose group), respectively. The carp were euthanized at the 30th day and gills were collected immediately. The ultrastructural and histopathological observations showed obvious necrosis characteristics and inflammatory injury in the CPF-treated groups. CPF exposure activated the MAPK pathway, in which the mRNA and protein expressions of extracellular signal-regulated (ERK), p38 MAP kinase (p38), and c-Jun N-terminal kinase (JNK) were increased; the mRNAs and proteins of NF-κB and TNF-α were activated; and the mRNAs and proteins of necroptosis related genes were changed (the mRNA and protein expression of RIPK1, RIPK3, MLKL, and FADD were increased and caspase-8 was decreased) with concentration dependency. Taken together, we concluded that CPF exposure activated the MAPK/NF-κB/TNF-α pathway, promoted inflammatory injure and evoked necroptosis in common carp gills. In addition, CPF-induced inflammation and necroptosis was concentration dependency. The toxic effects of CPF on gills provided data for both aquaculture and toxicological studies.

Polybrominated Diphenyl Ether Quinone Exposure Induces Atherosclerosis Progression via CD36-Mediated Lipid Accumulation, NLRP3 Inflammasome Activation, and Pyroptosis

Polybrominated diphenyl ethers (PBDEs) are used worldwide in brominated flame retardants. Although due to the forbiddance of their application, PBDEs continuously exist in the environment due to their persistence. Therefore, it is important to expand the understanding of their potential toxicities and human risks. The underlying cardiovascular toxicological mechanisms of PBDEs are still largely unknown. Our previous studies indicated that PBDE quinone-type metabolite (PBDEQ) exposure causes reactive oxygen species (ROS)-driven cytotoxicity and various types of programmed cell death. Here, we first reported PBDEQ exposure induces atherosclerosis progression in bone marrow-derived macrophages (BMDMs) isolated from wild-type C57BL/6 or CD36-/- mice and J774A.1 macrophage models. First, we found that PBDEQ exposure induced lipid accumulation in oxidized low-density lipid (Ox-LDL)-treated J774A.1 macrophages. Consistently, in J774A.1 macrophages, PBDEQ exposure resulted in NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and pyroptosis. CD36, a scavenger receptor responsible for the mediation of Ox-LDL uptake, was upregulated upon PBDEQ treatment. On the contrary, genetic knockout of CD36 or CD36 silencing by small interfering RNA efficiently attenuates PBDEQ-promoted lipid accumulation in BMDMs and J774A.1 macrophages. These findings highlight the effect of CD36 on the cardiovascular toxicity of PBDEs, which provides a better understanding of the pro-atherosclerosis effect of PBDEs.

The Bladder Is a Novel Target of Developmental Polychlorinated Biphenyl Exposure Linked to Increased Inflammatory Cells in the Bladder of Young Mice

Bladder inflammation is associated with several lower urinary tract symptoms that greatly reduce quality of life, yet contributing factors are not completely understood. Environmental chemicals are plausible mediators of inflammatory reactions within the bladder. Here, we examine whether developmental exposure to polychlorinated biphenyls (PCBs) leads to changes in immune cells within the bladder of young mice. Female mice were exposed to an environmentally relevant mixture of PCBs through gestation and lactation, and bladders were collected from offspring at postnatal day (P) 28-31. We identify several dose- and sex-dependent PCB effects in the bladder. The lowest concentration of PCB (0.1 mg/kg/d) increased CD45+ hematolymphoid immune cells in both sexes. While PCBs had no effect on CD79b+ B cells or CD3+ T cells, PCBs (0.1 mg/kg/d) did increase F4/80+ macrophages particularly in female bladder. Collagen density was also examined to determine whether inflammatory events coincide with changes in the stromal extracellular matrix. PCBs (0.1 mg/kg/d) decreased collagen density in female bladder compared to control. PCBs also increased the number of cells undergoing cell division predominantly in male bladder. These results implicate perturbations to the immune system in relation to PCB effects on the bladder. Future study to define the underlying mechanisms could help understand how environmental factors can be risk factors for lower urinary tract symptoms.

The challenge of micropollutants in surface water of the Yangtze River

The Yangtze River, the third largest river and supporting nearly one-third of Chinese population, has been severely polluted in recent decades. Among the numerous pollutants, organic micropollutants, as one kind of important emerging contaminants, are currently key contaminants of concern. However, few studies have focused on their mixture environmental impacts, especially for the complex environmental mixtures. In the current study, four categories of organic micropollutants, including 16 polycyclic aromatic hydrocarbons (PAHs), 32 polychlorinated biphenyls (PCBs), 27 organochlorine pesticides (OCPs) and 20 pharmaceutical and personal care products (PPCPs) are analyzed in 10 study sites on the Yangtze River. Subsequently, comprehensive risk assessment for micropollutant mixtures was conducted by risk quotient based on the sum of PEC/PNEC values (RQ_MEC/PNEC) and risk quotient based on the toxic units (RQ_STU). The mixture risk evaluation based on the detected environmental concentrations indicates that micropollutant mixtures in surface water of the Yangtze River exhibited relative high risks for aquatic organisms. The observed results revealed that mixture risk assessments have to consider the complexity of environmental samples; PCBs dominated main mixture risks in the upper stream; PAHs contributed major comprehensive risks in the middle stream; and OCPs were the key micropollutants in the downstream. The outcomes of the present study here can serve for pollution control in the Yangtze River, which provide the scientific underpinnings and regulatory reference for risk management and river protection.

Polybrominated diphenyl ethers quinone-induced intracellular protein oxidative damage triggers ubiquitin-proteasome and autophagy-lysosomal system activation in LO2 cells

Polybrominated diphenyl ethers (PBDEs), a kind of flame retardants, were widely used in the furniture, textile and electronics industries. Because of their lipophilic, persistent and bio-accumulative properties, PBDEs were listed on the Stockholm Convention as typical persistent organic pollutants (POPs). We have previously reported that a highly active, quinone-type metabolite of PBDEs (PBDEQ) causes DNA damage and subsequently triggers apoptosis. However, it is remaining unclear whether PBDEQ provokes protein damage and stimulates corresponding signaling cascade. Using human normal liver (LO2) cells as an in vitro model, we demonstrated that PBDEQ causes oxidative protein damage through excess reactive oxygen species (ROS). Consistently, we found PBDEQ exposure causes the depletion of protein thiol group, the appearance of carbonyl group and the accumulation of protein aggregates. Endoplasmic reticulum (ER) stress was involved in the repair of oxidized proteins. Under the scenario of severe damage, LO2 cells degrade oxidized proteins through ubiquitin-proteasome system (UPS) and autophagy. The blockage of these protein degradation pathways aggravates PBDEQ-induced cytotoxicity in LO2 cells, whilst antioxidant N-acetyl-cysteine (NAC) rescues PBDEQ-induced oxidative protein damage conversely. In summary, our current study first demonstrated PBDEQ-induced protein oxidative damage in LO2 cells, which offer a better understanding of the cytotoxicity of PBDEs and corresponding metabolites.

PCB118 Induces Inflammation of Islet Beta Cells via Activating ROS-NLRP3 Inflammasome Signaling

Background

Diabetes mellitus is a clinical syndrome caused by genetic and environmental factors. Growing evidence suggests that exposure to environmental endocrine disruptors and activation of NLRP3 inflammasome signaling play a vital role in diabetes. However, it is unclear how PCB118, a common environmental endocrine disruptor, contributes to the incidence of diabetes, and its specific mechanism of action is unknown. In this study, we explored whether ROS-induced NLRP3 inflammasome priming and activation were related to PCB118 exposure in mouse islet β-TC-6 cells and the mechanisms of diabetes.

Methods

Mouse islet β-TC-6 cells were cultured with PCB118 as a stimulating factor and ROS inhibitor N-acetyl cysteine (NAC) as an intervention. Cellular toxicity due to PCB118 was detected using the Cell Counting Kit-8; ROS was measured using DCFH-DA; the expressions of NLRP3, procaspase-1, caspase-1, pro-IL-1β, and IL-1β protein were detected by western blot; and IL-6, IL-18, and C-C chemokine ligand 2 (CCL-2) were measured by ELISA.

Results

PCB118 caused significant toxicity to the cells when the stimulation concentration was equal to or greater than 80 nmol/L at 72 hours (p < 0.05) and increased the levels of ROS, NLRP3, caspase-1, IL-1β, IL-6, IL-18, and CCL-2 (p < 0.05); the expressions of procaspase-1 and pro-IL-1β were downregulated in a dose-dependent manner after PCB118 exposure (p < 0.05), which was prevented by pretreatment with NAC (p < 0.05).

Conclusions

PCB118 can activate NLRP3 inflammasome signaling in islet beta cells via the oxidative stress pathway and cause inflammation in islet beta cells. It suggests that environmental endocrine disruptors play an important role in the inflammation of islet beta cells and may contribute to the development of diabetes through NLRP3 inflammatory signaling.

Polychlorinated biphenyl quinone regulates MLKL phosphorylation that stimulates exosome biogenesis and secretion via a short negative feedback loop

Polychlorinated biphenyls (PCBs) are one of the most refractory organic environmental pollutants that ubiquitous existence in nature. Due to the polymorphism of their metabolic pathway and corresponding downstream metabolites, PCBs' toxicities are complicated and need extended investigation. In the present study, we discovered a novel regulatory mechanism of PCB quinone metabolite-driven programmed cell death (PCD), namely, necroptosis. We first confirmed that PCB quinone induces cancerous HeLa and MDA-MB-231 cells necroptosis via the phosphorylation of mixed lineage kinase domain-like MLKL (p-MLKL). Then, we found that PCB quinone-stimulated p-MLKL enhances exosome biogenesis and secretion. Exosome interacts with p-MLKL and releases p-MLKL to the outside of the cell, and ultimately alleviating PCB quinone-induced necroptosis. The inhibition of exosome secretion by GW4869 significantly elevated necroptotic level, indicating the establishment of a short negative feedback loop of MLKL-exosome secretion upon PCB quinone challenge. Since exosome-mediated signaling showed great implications in various human diseases, this work may provide a new mechanism for PCBs-associated toxicity.

Polychlorinated biphenyl quinone induced the acquisition of cancer stem cells properties and epithelial-mesenchymal transition through Wnt/β-catenin

Polychlorinated biphenyls (PCBs) are persistent industrial pollutants that have been linked to breast cancer progression. However, their molecular mechanism(s) are currently unclear. Our previous assessment suggested that the highly reactive PCB metabolite 2,3,5-trichloro-6-phenyl-[1,4]-benzoquinone (PCB29-pQ) induces the metastasis of breast cancer. Here, our data illustrate that PCB29-pQ increases cancer stem cell (CSC) marker expression, resulting in an increase in the epithelial-mesenchymal transition (EMT) in MDA-MB-231 breast cancer cells; further, the Wnt/β-catenin pathway also becomes activated by PCB29-pQ. When the Wnt/β-catenin pathway is inhibited, the promotion of CSC properties and EMT by PCB29-pQ were accordingly reversed. In addition, the overproduction of reactive oxygen species (ROS) mediated by PCB29-pQ plays a key role in Wnt/β-catenin activation. Collectively, our current data designated the regulatory role of Wnt/β-catenin in PCB29-pQ-triggered acquisition of CSC properties and EMT.

Cytochrome P4501B1 in bone marrow is co-expressed with key markers of mesenchymal stem cells. BMS2 cell line models PAH disruption of bone marrow niche development functions

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants that are metabolized to carcinogenic dihydrodiol epoxides (PAHDE) by cytochrome P450 1B1 (CYP1B1). This metabolism occurs in bone marrow (BM) mesenchymal stem cells (MSC), which sustain hematopoietic stem and progenitor cells (HSPC). In BM, CYP1B1-mediated metabolism of 7, 12-dimethylbenz[a]anthracene (DMBA) suppresses HSPC colony formation within 6 h, whereas benzo(a)pyrene (BP) generates protective cytokines. MSC, enriched from adherent BM cells, yielded the bone marrow stromal, BMS2, cell line. These cells express elevated basal CYP1B1 that scarcely responds to Ah receptor (AhR) inducers. BMS2 cells exhibit extensive transcriptome overlap with leptin receptor positive mesenchymal stem cells (Lepr+ MSC) that control the hematopoietic niche. The overlap includes CYP1B1 and the expression of HSPC regulatory factors (Ebf3, Cxcl12, Kitl, Csf1 and Gas6). MSC are large, adherent fibroblasts that sequester small HSPC and macrophage in the BM niche (Graphic abstract). High basal CYP1B1 expression in BMS2 cells derives from interactions between the Ah-receptor enhancer and proximal promoter SP1 complexes, boosted by autocrine signaling. PAH effects on BMS2 cells model Lepr+MSC niche activity. CYP1B1 metabolizes DMBA to PAHDE, producing p53-mediated mRNA increases, long after the in vivo HSPC suppression. Faster, direct p53 effects, favored by stem cells, remain possible PAHDE targets. However, HSPC regulatory factors remained unresponsive. BP is less toxic in BMS2 cells, but, in BM, CYP1A1 metabolism stimulates macrophage cytokines (Il1b > Tnfa> Ifng) within 6 h. Although absent from BMS2 and Lepr+MSC, their receptors are highly expressed. The impact of this cytokine signaling in MSC remains to be determined.

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BMS2 and Lepr+MSC cells co-express CYP1B1 and 12 functional niche activity markers.

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CYP1B1 mRNA in BMS2 cells depends on activation of SP1 coupled to an AhR enhancer unit.

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DMBA metabolism by CYP1B1 activates p53 gene targets in BMS2 cells far more than BP.

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HSPC suppression by CYP1B1 generation of PAHDE requires rapid, non-genomic targets.

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BMS2 and Lepr+MSC share receptors activated by BP stimulation of macrophage cytokines.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and Polychlorinated Biphenyl Coexposure Alters the Expression Profile of MicroRNAs in the Liver Associated with Atherosclerosis

MicroRNAs (miRNAs) are a class of small RNAs that regulate gene expression. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) are persistent organic pollutants that exist as complex mixtures in vivo. When humans are simultaneously exposed to these compounds, the development of atherosclerosis is known to be enhanced. However, the roles of miRNA in TCDD- and PCB-induced atherosclerosis are largely unknown. Therefore, the present study is aimed at elucidating the possible dysregulation of miRNAs in atherogenesis induced by coexposure to TCDD and PCBs. Eight-week-old male ApoE^−/− mice were coexposed to TCDD (15 μg/kg) and Aroclor1254 (55 mg/kg, a representative mixture of PCBs) by intraperitoneal injection four times over a 6-week period. Microarray analysis of miRNAs and mRNAs in the liver of ApoE^−/− mice with or without TCDD and Aroclor1254 coexposure was performed. We discovered that 68 miRNAs and 1312 mRNAs exhibited significant expression changes in response to TCDD and PCB coexposure and revealed that both changed miRNAs and mRNAs are involved in cardiovascular disease processes. An integrated miRNA-mRNA approach indicated that miRNA-26a-5p, miRNA-193a-3p, and miRNA-30c-5p participated in specific TCDD and Aroclor1254 coresponsive networks which are relevant to the cardiovascular system development and function network. Furthermore, our results also indicated that miRNA-130a-3p and miRNA-376a-3p were novel players in the regulation of TCDD- and Aroclor1254-induced atherosclerosis pathways. In summary, our finding provided new insights into the mechanism of atherosclerosis in response to TCDD and PCB coexposure.

Polychlorinated Biphenyl Quinone Promotes Atherosclerosis through Lipid Accumulation and Endoplasmic Reticulum Stress via CD36

Polychlorinated biphenyls (PCBs) are persistent organic environmental pollutants. According to previous epidemiological reports, PCBs exposure is highly related to atherosclerosis. However, studies of PCBs metabolites and atherosclerosis and corresponding mechanism studies are scarce. In this study, we evaluated the effect of 2,3,5-trichloro-6-phenyl-[1,4]-benzoquinone (PCB29-pQ), a presumptive PCB metabolite, on atherosclerosis. Aortic plaques were increased in PCB29-pQ-treated ApoE^-/- mice [intraperitoneally (i.p.) injection of 5 mg/kg body weight of PCB29-pQ once a week for 12 continuous weeks, high-fat feeding]. We observed lipids accumulation and the release of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) in ApoE^-/- mice. In addition, we found that PCB29-pQ promoted the levels of total cholesterol, free cholesterol, triglyceride, and cholesteryl ester. Mechanism investigation indicated that PCB29-pQ induces the activation of three branches of endoplasmic reticulum (ER) stress response, that is, phosphorylated protein kinase R-like ER kinase (p-PERK), eukaryotic translation initiation factor 2α (eIF2α) and transcription factor 6 (ATF6), which is responsible for downstream necrosis. More importantly, we found the silence of CD36 is able to reverse PCB29-pQ-induced adverse effects completely. Overall, PCB29-pQ exposure resulted in lipid accumulation, ER stress response, apoptosis, and pro-inflammatory cytokines release via CD36, ultimately leading to atherosclerosis.

Polychlorinated biphenyl quinone induces hepatocytes iron overload through up-regulating hepcidin expression

Polychlorinated biphenyls (PCBs) are infamous industry by-products or additives, and increasing evidences demonstrated that their exposure is associate with adverse effects on human health. Liver, as the dominate site for xenobiotic metabolism, is apt to be the primary target of PCBs insult. Although PCBs' hepatic toxic effects have been extensively studied, however, the biotransformation of PCBs in liver and the toxicities of associated PCB metabolites are neglected at some extent. Thus, we choose 2,3,5-trichloro-6-phenyl-[1,4]-benzoquinone (PCB29-pQ), a surrogate PCB29 metabolite, and evaluated its contribution on hepatotoxicity. In the current study, we discovered PCB29-pQ-induced lipid peroxidation and iron overload both in vivo and in vitro. Further mechanistic research confirmed iron overload is caused by reactive oxygen species (ROS)-driven hepcidin disorder in hepatic cells, and the increase of hepcidin is regulated by the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2).