2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin promotes endothelial cell apoptosis through activation of EP3/p38MAPK/Bcl-2 pathway

Enrichment and distribution of 3,6-dichlorocarbazole in red crucian carp (Carassius auratus) and its hepatotoxicity

Polyhalogenated carbazoles (PHCZs) are a class of organohalogen compounds where the hydrogen atom on the carbazole ring is replaced by a halogen atom. In recent years, PHCZs have drawn increasing concern due to their persistence, dioxin-like toxicity, bioaccumulation, potential ecological hazards and widespread occurrence in the environment. Current research on the enrichment and depuration of PHCZs in biological tissues and organs is insufficient, and the liver toxicity is unclear. Herein, to understand the enrichment and elimination of 3,6-DCCZ in fish tissues and organs as well as the hepatotoxicity, we exposed the red crucian carp to 20 and 100 μg/L of 3,6-DCCZ for 20 days followed by a depuration period of 10 days. The 3,6-DCCZ enrichment in each organ tissue was classified from high to low: brain > liver, intestine, gill > muscle. For depuration, 3,6-DCCZ was quickly excreted in the various organs of the red crucian carp; however, the liver depuration was slow, with the concentration of 3,6-DCCZ was maintained at 0.25-0.35 μg/g. 3,6-DCCZ exposure at both tested concentrations induced oxidative stress in red crucian carp, causing lipid peroxidation and DNA damage, as well as some histopathological changes in the liver, such as cell vacuolization, nucleus pyknosis, nucleus pleomorphism, no nucleus areas. Additionally, the 3,6-DCCZ exposure at higher concentration (100 μg/L) caused more serious damage and abnormal lipid metabolism in the red crucian carp liver.

Transgenerational Transmission of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Effects in Human Granulosa Cells: The Role of MicroRNAs

Endocrine-disrupting chemicals (EDCs) might contribute to the increase in female-specific cancers in Western countries. 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD) is considered the "prototypical toxicant" to study EDCs' effects on reproductive health. Epigenetic regulation by small noncoding RNAs (sncRNAs), such as microRNAs (miRNA), is crucial for controlling cancer development. The aim of this study was to analyze transcriptional activity and sncRNA expression changes in the KGN cell line after acute (3 h) and chronic (72 h) exposure to 10 nM TCDD in order to determine whether sncRNAs' deregulation may contribute to transmitting TCDD effects to the subsequent cell generations (day 9 and day 14 after chronic exposure). Using Affymetrix GeneChip miRNA 4.0 arrays, 109 sncRNAs were found to be differentially expressed (fold change < -2 or >2; p-value < 0.05) between cells exposed or not (control) to TCDD for 3 h and 72 h and on day 9 and day 14 after chronic exposure. Ingenuity Pathway Analysis predicted that following the acute and chronic exposure of KGN cells, sncRNAs linked to cellular development, growth and proliferation were downregulated, and those linked to cancer promotion were upregulated on day 9 and day 14. These results indicated that TCDD-induced sncRNA dysregulation may have transgenerational cancer-promoting effects.

Role of intrinsic apoptosis in environmental exposure health outcomes

Environmental exposures are linked to diseases of high public health concern, including cancer, neurodegenerative disorders, and autoimmunity. These diseases are caused by excessive or insufficient cell death, prompting investigation of mechanistic links between environmental toxicants and dysregulation of cell death pathways, including apoptosis. This review describes how legacy and emerging environmental exposures target the intrinsic apoptosis pathway to potentially drive pathogenesis. Recent discoveries reveal that dynamic regulation of apoptosis may heighten the vulnerability of healthy tissues to exposures in children, and that apoptotic signaling can guide immune responses, tissue repair, and tumorigenesis. Understanding how environmental toxicants dysregulate apoptosis will uncover opportunities to deploy apoptosis-modulating agents for the treatment or prevention of exposure-linked diseases.

Targeting circular RNA-Glra2 alleviates retinal neurodegeneration induced by ocular hypertension

Glaucoma is a leading cause of irreversible vision loss characterized by retinal neurodegeneration. Circular RNAs (circRNAs) have emerged as the potential biomarkers and therapeutic targets for neurodegenerative diseases. However, the expression profiling of circRNAs in glaucomatous neurodegeneration has not been fully understood. In this study, we built a glaucomatous neurodegeneration model via the injection of microbeads into anterior chamber. circRNA expression profile and bioinformatics analysis revealed that compared with normal retinas, 171 circRNAs were dysregulated in the glaucomatous retinas, including 101 up-regulated circRNAs and 70 down-regulated circRNAs. Detecting the level of circular RNA-glycine receptor α2 subunit gene (cGlra2) in aqueous humor made it possible to distinguish glaucoma patients from cataract patients. Silencing of cGlra2 protected against oxidative stress- or hydrostatic pressure-induced retinal ganglion cell (RGC) injury in vitro. Moreover, silencing of cGlra2 retarded ocular hypertension-induced retinal neurodegeneration in vivo as shown by increased TUJ1 staining, reduced reactive gliosis, decreased retinal cell apoptosis, enhanced visual acuity, and improved retinal function. cGlra2 acted as a miRNA sponge to regulate RGC function through cGlra2/miR-144/BCL2L11 signaling axis. Collectively, this study provides novel insights into the underlying mechanism of retinal neurodegeneration and highlights the potential of cGlra2 as a target for the diagnosis and treatment of glaucoma.

A review of food contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin and its toxicity associated with metabolic disorders

Dioxins are a group of chemicals not only regarded as highly toxic trace environmental contaminants, but also considered typical contaminants in food. Dioxins spread across the ecosystem after factory manufacture, contaminate the soil and vegetation before either directly or indirectly entering the food chain through meat products, dairy products, and aquatic products. The compound in question poses a challenge for metabolic processes within the human body, due to its intricate mechanism for inducing diseases. Therefore, it presents a significant risk and is largely undisclosed. Dioxins are mainly exposed to humans by water, food, and air, as well as inducing organ failure and metabolic disorders through but not limited to the activation of aryl hydrocarbon receptors (AhR). As a notorious compound in the family of dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibits long-term toxic effects on diverse organs, which induces continuous metabolic disorders. This review discussed the mechanisms of TCDD-associated metabolic syndrome. The expression of the cytochrome P450 subfamily transfers TCDD into liver, promotes its accumulation in fat tissue, and affects cholesterol metabolism. This process also alters the glucose tolerance of the human organism, disrupting glucose metabolism. It can also elicit cardiovascular pathogenesis, exacerbate liver fibrosis and neuronal death. The long-term metabolic impact of this effect is found to be sex-related. This review summarized the toxicity of TCDD on the human metabolism system and discussed the plausible correlation between TCDD and five metabolic disorders, which helped offer novel insights for future research and therapeutic interventions for these ailments.

Blood Levels of Organochlorine Contaminants Mixtures and Cardiovascular Disease

Importance

Cardiovascular toxic effects derived from high exposures to individual organochlorine compounds are well documented. However, there is no evidence on low but continuous exposure to combined organochlorine compounds in the general population.

Objective

To evaluate the association of combined exposure to several organochlorine compounds, including organochlorine pesticides and polychlorinated biphenyls, with incident cardiovascular disease (CVD) in the general population.

Design, Setting, and Participants

This prospective nested case-control study included data from 2 cohorts: the Swedish Mammography Cohort-Clinical (SMC-C) and the Cohort of 60-Year-Olds (60YO), with matched case-control pairs based on age, sex, and sample date. Baseline blood sampling occurred from November 2003 to September 2009 (SMC-C) and from August 1997 to March 1999 (60YO), with follow-up through December 2017 (SMC-C) and December 2014 (60YO). Participants with myocardial infarction or ischemic stroke were matched with controls for composite CVD evaluation. Data were analyzed from September 2020 to May 2023.

Exposures

A total of 25 organochlorine compounds were measured in blood at baseline by gas chromatography-triple quadrupole mass spectrometry. For 7 compounds, more than 75% of the samples were lower than the limit of detection and not included.

Main Outcomes and Measures

Incident cases of primary myocardial infarction and ischemic stroke were ascertained via linkage to the National Patient Register (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes I21 and I63). The quantile-based g-computation method was used to estimate the association between the combined exposure to several organochlorine compounds and composite CVD.

Results

Of 1528 included participants, 1024 (67.0%) were female, and the mean (SD) age was 72 (7.0) years in the SMC-C and 61 (0.1) years in the 60YO. The odds ratio of composite CVD was 1.71 (95% CI, 1.11-2.64) per 1-quartile increment of total organochlorine compounds mixture. Organochlorinated pesticides were the largest contributors, and β-hexachlorocyclohexane and transnonachlor had the highest impact. Most of the outcome was not explained by disturbances in the main cardiometabolic risk factors, ie, high body mass index, hypertension, lipid alteration, or diabetes.

Conclusions and Relevance

In this prospective nested case-control study, participants with higher exposures to organochlorines had an increased probability of experiencing a cardiovascular event, the major cause of death worldwide. Measures may be required to reduce these exposures.

E prostanoid receptor-3 promotes oxidized low-density lipoprotein-induced human aortic smooth muscle cells inflammation

AIM

The progression of atherosclerosis can lead to the occurrence of multiple cardiovascular diseases (coronary heart disease, etc.). E prostanoid receptor-3 (EP3) is known to participate in the progression of atherosclerosis. This study aimed to investigate the mechanism by which EP3 modulates the development of atherosclerosis.

METHODS AND RESULTS

ApoE^-/- mice were used to construct in vivo model of atherosclerosis. Human aortic smooth muscle cells (HASMCs) were stimulated with oxidized low-density lipoprotein (ox-LDL) to construct in vitro model of atherosclerosis. mRNA expressions were assessed by qRT-PCR, and western blot was applied to assess the protein levels. CCK-8 assay was applied to assess the cell viability. The inflammatory cytokines levels were assessed by enzyme-linked immunosorbent assay, and flow cytometry was applied to assess cell apoptosis. In vivo experiment was constructed to investigate the impact of EP3 in atherosclerosis development. L-798106 (EP3 inhibitor) significantly inhibited the levels of pro-inflammatory cytokines in atherosclerosis in vivo. EP3 inhibitor (L-798106) significantly reversed ox-LDL-caused HASMCs injury via inhibiting the apoptosis and inflammatory responses (P < 0.05). The levels of interleukin-17 (IL-17) and intercellular adhesion molecule-1 (ICAM-1) in HASMCs were elevated by ox-LDL, whereas L-798106 or knockdown of cyclic AMP (cAMP) response element-binding protein (CREB) notably restored this phenomenon (P < 0.05). EP3 overexpression further aggravated ox-LDL-induced inflammation in HASMCs, and EP3 up-regulated the levels of IL-17 and ICAM-1 in ox-LDL-treated HASMCs (P < 0.05). EP3 up-regulation promoted the inflammatory responses in ox-LDL-treated HASMCs through mediation of cAMP/protein kinase A (PKA)/CREB/IL-17/ICAM-1 axis (P < 0.05).

CONCLUSIONS

EP3 inhibitor alleviates ox-LDL-induced HASMC inflammation via mediation of cAMP/PKA/CREB/IL-17/ICAM-1 axis. Our study might shed new lights on discovering novel strategies against atherosclerosis.

Dual role of NR4A1 in porcine ovarian granulosa cell differentiation and granulosa-lutein cell regression in vitro

This study aimed to investigate the role of NR4A1 in forskolin (FSK)-induced granulosa cell (GC) differentiation and PGF_2α-induced granulosa-lutein cell (GLC) regression. For experiment 1, primary porcine GCs were pre-cultured for 6 d before induced-differentiation by FSK with or without siNR4A1, and changes in GC proliferation, lipid droplets (LDs), and P₄ level were detected. For experiment 2, the GLC model was established by FSK as in experiment 1, and then PGF_2α was utilized to induce GLC regression with or without siNR4A1, changes in P₄ secretion, apoptosis proteins, and associated signaling pathway members were detected. Results showed that in experiment 1, FSK up-regulated NR4A1 expression during GC differentiation and decreased GC proliferation activity, which was reversed by siNR4A1. siNR4A1 inhibited the FSK-induced decreases in Cyclin B1/D1 and CDK1/2 mRNA abundances, and increases in P21/P27 mRNA abundances, and FSK-induced LD accumulation. FSK up-regulated P₄ secretion and StAR, CYP11A1 and HSD3B expression, decreased CYP19A1 expression, which were reversed by siNR4A1 except for StAR expression. In experiment 2, PGF_2α induced NR4A1 expression and reduced GLC viability, which were reversed by siNR4A1. Compared with PGF_2α group, the levels of P₄ secretion and StAR expression were higher in PGF_2α+siNR4A1 group, while CYP11A1 and HSD3B expressions held at low levels. siNR4A1 inhibited PGF_2α-induced expression of apoptosis proteins (caspase3, Bax, Fas, TNFa), ATF3, and phosphorylated MAPKs (ERK1/2, P38, JNK). In summary, NR4A1 is involved in regulating porcine GC differentiation and GLC regression as well as the changes in cell proliferation, apoptosis, steroidogenesis, and MAPK pathways, which provide a theoretical basis for further understanding of the mechanism of porcine luteal formation and regression.

Melatonin reduces melanogenesis by inhibiting the paracrine effects of keratinocytes

Keratinocytes regulate melanogenesis in a paracrine manner. Previous studies have shown that melatonin can directly inhibit melanin production in the melanocytes. However, it is unclear whether melatonin can also indirectly regulate melanogenesis through the keratinocytes. In this study, we explored the role of melatonin in regulating keratinocyte-mediated melanogenesis using reconstructed human epidermis (RHE). Melatonin showed an inhibitory effect on melanin synthesis in this model. Furthermore, the conditioned media from melatonin-treated HaCaT cells downregulated melanogenesis-related genes, including MITF, TYR, TYRP1, DCT and RAB27A in the pigment MNT1 cells, and decreased levels of phosphorylated ERK, JNK and p38. RNA sequencing further showed that mitochondrial functions and oxidative stress pathway in the MNT1 cells were inhibited by the conditioned medium from melatonin-treated HaCaT cells. Furthermore, melatonin reduced the secretion of ET-1 and PTGS2 from HaCaT cells by inhibiting the JAK2/STAT3 signalling pathway. In conclusion, melatonin downregulates the paracrine factors ET-1 and PTGS2 in the keratinocytes by inhibiting the JAK2/STAT3 pathway, which reduces melanin production in pigment cells. Thus, melatonin has a potential therapeutic effect on skin pigmentation disorders.

Inhibition of Prostaglandin E2 Receptor EP3 Attenuates Oxidative Stress and Neuronal Apoptosis Partially by Modulating p38MAPK/FOXO3/Mul1/Mfn2 Pathway after Subarachnoid Hemorrhage in Rats

Oxidative stress and neuronal apoptosis contribute to pathological processes of early brain injury (EBI) after subarachnoid hemorrhage (SAH). Previous studies demonstrated that the inhibition of prostaglandin E2 receptor EP3 suppressed oxidative stress and apoptotic effects after Alzheimer's disease and intracerebral hemorrhage. This study is aimed at investigating the antioxidative stress and antiapoptotic effect of EP3 inhibition and the underlying mechanisms in a rat mode of SAH. A total of 263 Sprague-Dawley male rats were used. SAH was induced by endovascular perforation. Selective EP3 antagonist L798106 was administered intranasally at 1 h, 25 h, and 49 h after SAH induction. EP3 knockout CRISPR and FOXO3 activation CRISPR were administered intracerebroventricularly at 48 h prior to SAH, while selective EP3 agonist sulprostone was administered at 1 h prior to SAH. SAH grade, neurological deficits, western blots, immunofluorescence staining, Fluoro-Jade C staining, TUNEL staining, 8-OHdG staining, and Nissl staining were conducted after SAH. The expression of endogenous PGES2 increased and peaked at 12 h while the expression of EP1, EP2, EP3, EP4, and Mul1 increased and peaked at 24 h in the ipsilateral brain after SAH. EP3 was expressed mainly in neurons. The inhibition of EP3 with L798106 or EP3 KO CRISPR ameliorated the neurological impairments, brain tissue oxidative stress, and neuronal apoptosis after SAH. To examine potential downstream mediators of EP3, we examined the effect of the increased expression of activated FOXO3 following the administration of FOXO3 activation CRISPR. Mechanism studies demonstrated that L798106 treatment significantly decreased the expression of EP3, p-p38, p-FOXO3, Mul1, 4-HNE, Bax, and cleaved caspase-3 but upregulated the expression of Mfn2 and Bcl-2 in SAH rats. EP3 agonist sulprostone or FOXO3 activation CRISPR abolished the neuroprotective effects of L798106 and its regulation on expression of p38MAPK/FOXO3/Mul1/Mfn2 in the ipsilateral brain after SAH. In conclusion, the inhibition of EP3 by L798106 attenuated oxidative stress and neuronal apoptosis partly through p38MAPK/FOXO3/Mul1/Mfn2 pathway post-SAH in rats. EP3 may serve as a potential therapeutic target for SAH patients.

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.

MicroRNA-30a-3p acts as a tumor suppressor in MHCC-97H hepatocellular carcinoma cells by targeting COX-2

MicroRNAs (miRNAs) are small, noncoding RNAs which can bind to target mRNAs and regulate gene expression. Increasing evidences suggest that miRNAs play an important role in driving hepatocellular carcinoma (HCC) progression by regulating tumor cell proliferation, apoptosis, invasion, and migration. In this study, we demonstrated that the expression of microRNA-30a-3p (miR-30a-3p) was reduced in HCC cell lines in comparison to immortalized liver cell line, LO2. Augmented miR-30a-3p level markedly inhibited MHCC-97H cell growth, migration and invasion in vitro. MiR-30a-3p was also found to inhibit tumor growth in vivo using tumor-bearing mice. Mechanismly, COX-2 was discovered to be a direct and functional target of miR-30a-3p in MHCC-97H cells. Raised miR-30a-3p expression reduced the transcriptional level of COX-2 in MHCC-97H cells, while genetically upregulated COX-2 expression was able to reverse the function of miR-30a-3p-mediated suppression of MHCC-97H cells growth, migration and invasion. In addition, we found that using a COX-2 inhibitor, celecoxib, could enhance the anti-metastatic role of miR-30a-3p in MHCC-97H cells. Lastly, we found that decreased COX-2 protein level affected PGE2 production, leading to lower Bcl-2, Caspase-3, MMP2 and MMP9 expression but higher Bax and E-cadherin expression, which in turn culminated in higher rates of cell death and lower rates of cell migration. Taken together, our findings demonstrate that miR-30a-3p could be a target for the treatment of hepatocellular carcinoma cells progression.

MicroRNA-214 targets COX-2 to antagonize indoxyl sulfate (IS)-induced endothelial cell apoptosis

Cardiovascular disease (CVD) serves as the major cause of mortality in chronic kidney disease (CKD) patients. The injury of endothelium associated with the long-term challenge of uremic toxins including the toxic indoxyl sulfate (IS) is one of key pathological factors leading to CVD. However, the mechanisms of uremic toxins, especially the IS, resulting in endothelial injury, remain unclear. miR-214 was reported to contribute to the pathogenesis of cardiovascular diseases, while its role in IS-induced endothelial cell apoptosis is unknown. In this study, we investigated the role of microRNA-214 (miR-214) in IS-induced endothelial cell apoptosis and the underlying mechanisms using mouse aortic endothelial cells (MAECs). Following IS treatment, miR-214 was significantly downregulated in MAECs in line with enhanced cell apoptosis. Meanwhile, COX-2 was upregulated at both mRNA and protein levels along with increased secretion of PGE₂ in medium. To define the role of miR-214 in IS-induced endothelial cell apoptosis, we modulated miR-214 level in MAECs and found that overexpression of miR-214 markedly attenuated endothelial cell apoptosis, while antagonism of miR-214 deteriorated cell death after IS challenge. Further analyses confirmed that COX-2 is a target gene of miR-214, and the inhibition of COX-2 by a specific COX-2 inhibitor NS-398 strikingly attenuated IS-induced endothelial cell apoptosis along with a significant blockade of PGE₂ secretion. In conclusion, this study demonstrated an important role of miR-214 in protecting against endothelial cell damage induced by IS possibly by direct downregulation of COX-2/PGE₂ axis.

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.

TCDD promotes liver fibrosis through disordering systemic and hepatic iron homeostasis

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) is a toxic environmental pollutant which can cause severe health problems, such as fibrosis. However, the toxic effects and related mechanism of TCDD on the liver remain largely unknown. In this study, we established a liver fibrosis mouse model upon exposure of TCDD, as evidenced by increased collagen I, tumor growth factor β1 (TGFβ1), α-smooth muscle actin (α-SMA), and Masson staining. Meanwhile, there was also a significant increase of inflammatory factors and TUNEL-positive hepatocytes in liver, indicating that liver inflammation and hepatic cell apoptosis occurred. In addition, increased serum and liver iron were concomitant with liver injury induced by TCDD. We further investigated the mechanism underlying TCDD-induced hepatocyte apoptosis through apoptosis polymerase chain reaction array, and found that a crucial apoptosis-related gene, cell death-inducing DFF45-like effector b (Cideb), was significantly increased in primary hepatocytes from TCDD-exposed mice, and accompanied by liver iron deposition in hepcidin knockout mice. Therefore, Cideb depletion could effectively attenuated TCDD or iron induced cell death related genes expression. In conclusion, our results showed that iron-induced Cideb expression played a critical role in promoting TCDD-induced hepatocyte apoptosis and liver fibrosis, which provide a novel mechanism for understanding TCDD-induced liver injury.

Exposure to dietary polychlorinated biphenyls and dioxins, and its relationship with subclinical coronary atherosclerosis: The Aragon Workers' Health Study

BACKGROUND

Experimental evidence has revealed that exposure to polychlorinated biphenyls (PCBs) and dioxins directly impairs endothelial function and induces atherosclerosis progression. In the general population, despite a small number of recent studies finding a link between PCBs, and stroke and myocardial infraction, the association with early coronary atherosclerosis has not been examined yet.

OBJECTIVE

To examine whether dietary exposure to PCBs and dioxins is associated with subclinical coronary atherosclerosis in a middle-aged men.

DESIGN

Cross-sectional analysis comprising 1844 men in their 50 s and free of cardiovascular disease, who participated in the Aragon Workers' Health Study (AWHS). Individual dietary exposures to PCBs and dioxins were estimated by the contaminant's concentration in food coupled with the corresponding consumption and then participants were classified into quartiles of consumption. Coronary artery calcium score (CACS) was assessed by computerized tomography. We conducted ordered logistic regressions to estimate the odds ratio (OR) and 95% confidence intervals (CIs) for progression to the categories of more coronary artery calcium, adjusting for potential confounders.

RESULTS

Among the participants, coronary calcium was not shown in 60.1% (n = 1108), 29.8% had a CACS > 0 and <100 (n = 550), and the remaining 10.1% (n = 186) had a CACS ≥ 100. Compared with those in the first quartile of PCBs exposure, those in the fourth one had an increased odds for having coronary calcium (OR 2.02, 95% CI [1.18, 3.47], p trend 0.019) and for having progressed to categories of more intense calcification (OR 2.03, 95% CI [1.21, 3.40], p trend 0.012). However, no association was found between dietary dioxins exposure and prevalent coronary artery calcium.

CONCLUSIONS

In this general male population, dietary exposure to PCBs, but not to dioxins, was associated with a higher prevalence of coronary calcium and to more intense subclinical coronary atherosclerosis. PCBs exposure seems to increase the risk of coronary disease in men from the very early stages.

Aryl hydrocarbon receptor pathway: Role, regulation and intervention in atherosclerosis therapy (Review)

The aryl hydrocarbon receptor (AhR) is a ligand‑activated transcription factor originally isolated and characterized as the dioxin or xenobiotic receptor. With the discovery of endogenous ligands and studies of AhR knockout mice, AhR has been found to serve an important role in several biological processes, including immune responses and developmental and pathological regulation. In particular, it has been considered as a new major player in cardiovascular diseases. Recent studies have revealed that the development of atherosclerosis is closely associated with AhR function. However, the roles of the AhR in the pathological development of atherosclerosis and atherosclerosis‑associated diseases remain unclear. The current review presents the molecular mechanisms involved in the regulation of AhR expression during inflammation, oxidative stress and lipid deposition. Additionally, the role of the AhR in atherosclerosis and atherosclerosis‑associated diseases is reviewed.

2,3,7,8-Tetrachlorodibenzo-p-dioxin promotes injury-induced vascular neointima formation in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental pollutant that causes cardiovascular toxicity. The phenotypic transformation of vascular smooth muscle cells (VSMCs) from the contractile to the synthetic phenotype is a hallmark of vascular response to injury. However, the precise role and molecular mechanism of TCDD in vascular remodeling remains unknown. In the present study, we found that TCDD treatment promoted VSMC phenotypic transition from contractile to synthetic phenotype and exaggerated vascular neointimal hyperplasia after wire injury in mice. TCDD treatment enhanced VSMC entry into cell cycle from G0/G1 phase to S and G2/M phase. The expression of cyclin D1, cyclin-dependent kinase 4 (CDK4), and its phosphorylation were coordinately increased in response to TCDD treatment. Knocking down of aryl hydrocarbon receptor (AHR) inhibited VSMC phenotypic transition induced by TCDD and promoted S/G2 phase cell cycle arrest. TCDD treatment markedly increased oncogenic c-Jun gene expression in VSMCs. ChIP assay revealed the direct binding of AHR on the promoter of c-Jun to up-regulate the mRNA expression of c-Jun. Silencing of c-Jun gene enhanced the expression of p53 and p21, whereas attenuated the expression of CDK4 and cyclin D1 leading to the decrease in the TCDD-stimulated VSMC proliferation and synthetic phenotype transition in vitro. In vivo study showed that genetic ablation of c-Jun in VSMCs restricted injury-induced neointimal hyperplasia in TCDD-treated mice. Thus, TCDD exposure exaggerated injury-induced vascular remodeling by the activation of AHR and up-regulation of the expression of its target gene c-Jun, indicating that inhibition of AHR may be a promising prevention strategy for TCDD-associated cardiovascular diseases.-Guo, S., Zhang, R., Liu, Q., Wan, Q., Wang, Y., Yu, Y., Liu, G., Shen, Y., Yu, Y., Zhang, J. 2,3,7,8-Tetrachlorodibenzo-p-dioxin promotes injury-induced vascular neointima formation in mice.

Metformin promotes proliferation and suppresses apoptosis in Ox-LDL stimulated macrophages by regulating the miR-34a/Bcl2 axis

Background: Metformin, an antidiabetic drug, has been reported to be involved in atherosclerosis (AS). In this study, the effects of metformin on oxidized low-density lipoprotein (Ox-LDL)-induced macrophage apoptosis were investigated, and the mechanisms involved in this process were examined. Methods: qRT-qPCR analysis was performed to detect the expression of miR-34a in macrophage cells. Cell proliferation was determined by MTT assays and colony formation assays. Cell apoptosis was assessed by the detection of apoptotic rate and caspase 3 activity. Western blot analysis was performed to evaluate the expression of Bcl2 protein. Results: Metformin treatment promoted proliferation and suppressed apoptosis in macrophages following the treatment of oxidized low-density lipoprotein (Ox-LDL). Metformin could inhibit miR-34a in macrophages. miR-34a overexpression could reverse the effect of metformin on proliferation and apoptosis in Ox-LDL-treated macrophages. Moreover, metformin could increase the expression of the miR-34a target gene Bcl2. Furthermore, metformin treatment exerted the pro-proliferation and anti-apoptosis effect through regulating Bcl2 expression in Ox-LDL-stimulated macrophages. Conclusion: Metformin facilitated proliferation and inhibited apoptosis of macrophages treated with Ox-LDL through the miR-34a/Bcl2 axis, indicating the potential value of metformin in AS therapy.

A Toxicogenomic Approach Reveals a Novel Gene Regulatory Network Active in In Vitro and In Vivo Models of Thyroid Carcinogenesis

Epidemiological and experimental studies emphasize the link between environmental chemicals exposure and thyroid cancer. However, this association is strongly debated and the mechanisms of action of environmental thyroid carcinogens still need to be identified. The analysis of in vitro transcriptomic data developed to investigate the effects of chlorpyrifos on immortalized thyrocytes highlighted the impaired expression of genes involved in endodermal carcinogenesis. This endodermal carcinogenic gene-network (ECGN, including Zfp36l2, Dmbt1, Ddit4), was validated in cellular and mouse models of thyroid carcinogenesis, characterized by the constitutive activation of the mitogen-activated protein kinase (MAPK) pathway and in immortalized thyrocytes exposed to tetrachlorodibenzo-p-dioxin (TCDD) and chlorpyrifos (CPF). The mRNA levels of Zfp36l2, Dmbt1 and Ddit4 were increased in models characterized by MAPK activation or following TCDD exposure, whereas they were inhibited by CPF exposure. Overall, the ECGN transcripts identify a novel gene-regulatory network associated with thyroid carcinogenesis promoted by genetic mutation or by environmental carcinogens. The latter have opposite effects on the modulation of the ECGN transcripts according to their mechanisms of action in promoting carcinogenesis. Therefore, the analyses of ECGN might be helpful in discriminating compounds that promote cellular survival associated or not to proliferation of thyrocytes.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin increases the activation of aryl hydrocarbon receptor and is associated with the aggressiveness of osteosarcoma MG-63 osteoblast-like cells

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor whose activity is modulated by xenobiotics and physiological ligands. Activation of the AhR by environmental xenobiotics may induce a conformational change in AhR and has been implicated in a variety of cellular processes, including inflammation and tumorigenesis. It is unknown whether the activation of AhR serves a role in modulating the progression of osteosarcoma. The osteosarcoma cell line MG-63, was treated with AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD treatment degrades AhR expression through activation of the AhR signaling pathway, however there were no survival differences observed in MG-63 cells. There were concomitant elevations of cyclooxygenase-2 and receptor activator of nuclear factor-κB ligand secretion from MG-63 cells upon TCDD treatment on a protein and mRNA level at 24 and 72 h. In addition, TCDD treatment also increases the production of prostaglandin E2 on MG-63 cells, and induces the expression of chemokine receptor CXCR4. However, CXCL12 production was not altered in MG-63 cells when stimulated with TCDD. The AhR antagonist CH-223191, blocks the effects on TCDD-induced RANKL, COX-2, PGE2 and CXCR4 changes. In conclusion, these findings suggest that AhR signal therapy should be further explored as a therapeutic option for the treatment of osteosarcoma.

Adaptive changes in global gene expression profile of lung carcinoma A549 cells acutely exposed to distinct types of AhR ligands

Exposure to persistent ligands of aryl hydrocarbon receptor (AhR) has been found to cause lung cancer in experimental animals, and lung adenocarcinomas are often associated with enhanced AhR expression and aberrant AhR activation. In order to better understand the action of toxic AhR ligands in lung epithelial cells, we performed global gene expression profiling and analyze TCDD-induced changes in A549 transcriptome, both sensitive and non-sensitive to CH223191 co-treatment. Comparison of our data with results from previously reported microarray and ChIP-seq experiments enabled us to identify candidate genes, which expression status reflects exposure of lung cancer cells to TCDD, and to predict processes, pathways (e.g. ER stress, Wnt/β-cat, IFNɣ, EGFR/Erbb1), putative TFs (e.g. STAT, AP1, E2F1, TCF4), which may be implicated in adaptive response of lung cells to TCDD-induced AhR activation. Importantly, TCDD-like expression fingerprint of selected genes was observed also in A549 cells exposed acutely to both toxic (benzo[a]pyrene, benzo[k]fluoranthene) and endogenous AhR ligands (2-(1H-Indol-3-ylcarbonyl)-4-thiazolecarboxylic acid methyl ester and 6-formylindolo[3,2-b]carbazole). Overall, our results suggest novel cellular candidates, which could help to improve monitoring of AhR-dependent transcriptional activity during acute exposure of lung cells to distinct types of environmental pollutants.

Docosahexaenoic acid reversed atherosclerotic changes in human endothelial cells induced by palmitic acid in vitro

Abnormal activity of atherosclerotic endothelial cells paving luminal surface of blood vessels has been described in many diseases. It has been reported that natural polyunsaturated fatty acids such as docosahexaenoic acid exert therapeutic effects in atherosclerotic condition. Human umbilical vein endothelial cells were treated with 1mM palmitic acid for 48 hours and exposed to 40μM docosahexaenoic acid for the next 24 hours. Real-time polymerase chain reaction analysis was used to measure the expression of PTX3, iNOS, and eNOS. The level of nitric oxide was detected by Griess reagent. The transcription level of genes participating in coagulation and blood pressure was studied by polymerase chain reaction array. Docosahexaenoic acid improved the survival rate by reducing apoptosis rate (P < .05). Compared with that of the group given palmitic acid, attenuation of proinflammatory status was indicated by reduced interleukin-6 (P < .05) and prostaglandin E₂ levels. All genes PTX3, iNOS, and eNOS were down-regulated after being exposed to docosahexaenoic acid. Nitric oxide contents were not changed in cells exposed to docosahexaenoic acid. Polymerase chain reaction array confirmed the reduction of LPA, PDGFβ, ITGA2, SERPINE1, and FGA after exposure to docosahexaenoic acid for 24 hours (P < .05). Docosahexaenoic acid had potential to blunt atherosclerotic changes in the modulation of genes controlling blood coagulation, pressure, and platelet function.

SIGNIFICANCE OF THE STUDY

The current experiment showed that docosahexaenoic acid could reverse atherosclerotic changes in human endothelial cells induced by palmitic acid. The increased levels of interleukin-6 and prostaglandin E₂ in atherosclerotic cells were returned to near-to-normal status. Gene expression analysis showed a reduced activity of genes participating in atherosclerotic endothelial cells treated by docosahexaenoic acid. The expression of genes related to cell clotting activity was also similar to that of normal cells.

Protective effects of icariin on human vascular endothelial cells induced by oxidized low-density lipoprotein via modulating caspase-3 and Bcl-2

Icariin belongs to the family of flavonoids that is extracted from Epimedium brevicornum Maxim, and exhibits antioxidative, antitumorigenic, antiosteoporotic, immunoregulatory and antiatherosclerotic properties. To understand the mechanisms underlying the antiatherosclerotic properties of icariin, the present study investigated the effects of icariin on human vascular endothelial cells (HUVECs) following treatment with oxidized low‑density lipoprotein (ox‑LDL). Thus, following pretreatment with icariin at four various concentrations (0, 10, 20 and 40 µM), HUVECs were stimulated with ox‑LDL (100 µg/ml). The viability of cells was evaluated via an MTT assay and flow cytometry was performed to assess apoptosis. Additionally, the protein and mRNA expression levels of apoptosis regulator Bcl‑2 (Bcl‑2) and caspase‑3 were determined by western blotting and reverse transcription‑quantitative polymerase chain reaction. The findings of the present study indicated that icariin prevented injury and apoptosis in HUVECs following ox‑LDL treatment, in particular via the regulation of protein and mRNA expression levels of Bcl-2 and caspase-3.