Effects of quercetin on Aroclor 1254-induced expression of CYP450 and cytokines in pregnant rats

Toxic effects of Aroclor 1254 on rat liver and modifying roles of selenium

Polychlorinated biphenyls (PCBs) were used in different industrial areas and banned due to their high toxicity. Aroclor 1254 (A1254), commercial PCB congener, accumulates in environment leading to high human exposure. A1254 may cause hepatotoxicity, metabolic and endocrine disorders. In our study, 3-week-old male rats were separated into 6 groups: C (0.15 mg/kg Se in diet); SeS (1 mg/kg Se in diet); SeD (0.05 mg/kg Se in diet); A1254 receiving groups (A; ASeS; ASeD) were given 10 mg/kg/day A1254 orally for last 15 days of feeding period with control, SeD or SeS diet, respectively, for 5 weeks. Histopathology, oxidant/antioxidant balance, apoptosis and cell cycle proteins (p53, p21) in liver were evaluated. Our results suggest that A1254 leads to changes in histology, oxidative stress and apoptosis. Selenium deficiency augments oxidative stress and apoptosis while selenium supplementation is partially protective. More mechanistic in vivo experiments are necessary for evaluation of hepatotoxicity of PCBs.

Effects of quercetin on immune regulation at the maternal-fetal interface

The imbalance of immune homeostasis at the maternal-fetal interface is closely related to adverse pregnancy outcomes, so it has become one of the hot research topics in the reproductive field. Quercetin is rich in common TCM kidney-tonifying herbs such as dodder and lorathlorace, and has shown pregnancy protection function. As a common flavonoid, quercetin has powerful anti-inflammatory, antioxidant, estrogen-like effects; and it can regulate the functions of maternal-fetal interface immune cells (such as decidual natural killer cells, decidual macrophages, T cells, dendritic cells and myeloid-derived suppressor cells), exovillous trophoblast cells, decidual stromal cells, and the activities of their cytokines. Quercetin maintains the dynamic balance of maternal and fetal immunity by attenuating cytotoxicity, reducing excessive apoptosis of the tissue cells and inhibiting excessive inflammatory reactions. In this article, the role and molecular mechanism of quercetin in the immunomodulatory process of the maternal and fetal interface are reviewed to provide reference for the treatment of recurrent spontaneous abortion and other adverse pregnancy outcomes.

Gene×environment interactions in autism spectrum disorders

There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.

Emissions of dioxins and dioxin-like compounds and incidence of hepatocellular carcinoma in the United States

Ambient dioxin exposure from industrial sources, excluding exposures from occupations and accidental releases/contamination, may be associated with risk of developing hepatocellular carcinoma (HCC). The objective of this study was to examine the association between county-level ambient dioxin air emissions from industrial sources and HCC risk in the US. We obtained information on 90,359 incident HCC cases diagnosed between 2000 and 2016 from population-based cancer registries across the US in the Surveillance, Epidemiology, and End Results (SEER) database. Dioxin emissions from 1987 to 2007 from a nationwide spatial database of historical dioxin-emitting facilities were linked to the SEER county of residence at diagnosis using a geographic information system (GIS). Poisson regression with robust variance estimation was used to calculate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for the association between county-level dioxin emissions and HCC rates adjusting for individual-level age at diagnosis, sex, race/ethnicity, year of diagnosis, SEER registry, and county-level information on health conditions, lifestyle factors, and socioeconomic status. There was no association between dioxin emissions based on the number of dioxin-emitting facilities within a county or average annual emissions within a county and HCC risk. In analyses by facility type, there were positive associations between county-level dioxin emissions from coal-fired power plants (adjusted IRR 1.09, 95% CI 1.01-1.17), but not with the number of these facilities. Similarly, positive associations for industrial boilers and sewage sludge incinerators were evident, but not consistent across both exposure metrics. Future research should incorporate individual-level data to further explore the findings suggested by these ecologic analyses.

Upregulation of CCL7, CCL20, CXCL2, IL-1β, IL-6 and MMP-9 in Skin Samples of PCB Exposed Individuals-A Preliminary Study

Polychlorinated biphenyls (PCBs) are well known immunotoxic and carcinogenic compounds. Although cutaneous symptoms are the hallmark of exposure to these compounds, exact pathophysiologic mechanisms are not well understood. We took skin biopsies from moderately high PCB exposed workers (n = 25) after an informed consent and investigated the expression of immunological markers such as CCL-7, CCL-20, CXCL2, IL-1β and IL-6, as well as the matrix metalloproteinase MMP-9, EPGN and NRF2 by RT-qPCR, and compared expression levels with plasma PCB levels. Statistical analyses showed a significant correlation between CCL-20, CXCL2, IL-6, IL-1β, CCL-7 and MMP-9 and PCB serum levels. EPGN and NRF2 were not correlated to PCB levels in the blood. We found a significant correlation of genes involved in autoimmune, auto-inflammatory and carcinogenesis in skin samples of PCB exposed individuals with elevated plasma PCB levels. Confirmation of these findings needs to be performed in bigger study groups and larger gen-sets, including multiple housekeeping genes. Further study needs to be performed to see whether a chronical exposure to these and similar compounds can cause higher incidence of malignancies and inflammatory disease.

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.

Key Characteristics of Cardiovascular Toxicants

BACKGROUND

The concept of chemical agents having properties that confer potential hazard called key characteristics (KCs) was first developed to identify carcinogenic hazards. Identification of KCs of cardiovascular (CV) toxicants could facilitate the systematic assessment of CV hazards and understanding of assay and data gaps associated with current approaches.

OBJECTIVES

We sought to develop a consensus-based synthesis of scientific evidence on the KCs of chemical and nonchemical agents known to cause CV toxicity along with methods to measure them.

METHODS

An expert working group was convened to discuss mechanisms associated with CV toxicity.

RESULTS

The group identified 12 KCs of CV toxicants, defined as exogenous agents that adversely interfere with function of the CV system. The KCs were organized into those primarily affecting cardiac tissue (numbers 1-4 below), the vascular system (5-7), or both (8-12), as follows: 1) impairs regulation of cardiac excitability, 2) impairs cardiac contractility and relaxation, 3) induces cardiomyocyte injury and death, 4) induces proliferation of valve stroma, 5) impacts endothelial and vascular function, 6) alters hemostasis, 7) causes dyslipidemia, 8) impairs mitochondrial function, 9) modifies autonomic nervous system activity, 10) induces oxidative stress, 11) causes inflammation, and 12) alters hormone signaling.

DISCUSSION

These 12 KCs can be used to help identify pharmaceuticals and environmental pollutants as CV toxicants, as well as to better understand the mechanistic underpinnings of their toxicity. For example, evidence exists that fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5)] air pollution, arsenic, anthracycline drugs, and other exogenous chemicals possess one or more of the described KCs. In conclusion, the KCs could be used to identify potential CV toxicants and to define a set of test methods to evaluate CV toxicity in a more comprehensive and standardized manner than current approaches. https://doi.org/10.1289/EHP9321.

The Preventive Effects of Quercetin on Preterm Birth Based on Network Pharmacology and Bioinformatics

Our previous study has shown that quercetin prevented lipopolysaccharide-induced preterm birth. This study aims to clarify the potential targets and biological mechanisms of quercetin in preventing preterm birth. We used bioinformatics databases to collect the candidate targets for quercetin and preterm birth. The biological functions and enriched pathways of the intersecting targets were analyzed by gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Then, the hub targets were identified by cytoscape plugin cytoHubba from the protein-protein interaction network. We obtained 105 targets for quercetin in preventing preterm birth. The biological processes of the intersecting targets are mainly involved in steroid metabolic process, drug metabolic process, oxidation-reduction process, omega-hydroxylase P450 pathway, positive regulation of cell migration, negative regulation of apoptotic process, and positive regulation of cell proliferation. The highly enriched pathways were steroid hormone biosynthesis, metabolism of xenobiotics by cytochrome P450, proteoglycans in cancer, focal adhesion, and arachidonic acid metabolism. The ten hub targets for quercetin in preventing preterm birth were AKT serine/threonine kinase 1, mitogen-activated protein kinase 3, epidermal growth factor receptor, prostaglandin-endoperoxide synthase 2, mitogen-activated protein kinase 1, estrogen receptor 1, heat shock protein 90 alpha family class A member 1, mitogen-activated protein kinase 8, androgen receptor, and matrix metallopeptidase 9. Molecular docking analysis showed good bindings between these proteins and quercetin. In conclusion, these findings highlight the key targets and molecular mechanisms of quercetin in preventing preterm birth.

The influence of sex, genotype, and dose on serum and hippocampal cytokine levels in juvenile mice developmentally exposed to a human-relevant mixture of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are pervasive environmental contaminants implicated as risk factors for neurodevelopmental disorders (NDDs). Immune dysregulation is another NDD risk factor, and developmental PCB exposures are associated with early life immune dysregulation. Studies of the immunomodulatory effects of PCBs have focused on the higher-chlorinated congeners found in legacy commercial mixtures. Comparatively little is known about the immune effects of contemporary, lower-chlorinated PCBs. This is a critical data gap given recent reports that lower-chlorinated congeners comprise >70% of the total PCB burden in serum of pregnant women enrolled in the MARBLES study who are at increased risk for having a child with an NDD. To examine the influence of PCBs, sex, and genotype on cytokine levels, mice were exposed throughout gestation and lactation to a PCB mixture in the maternal diet, which was based on the 12 most abundant PCBs in sera from MARBLES subjects. Using multiplex array, cytokines were quantified in the serum and hippocampus of weanling mice expressing either a human gain-of-function mutation in ryanodine receptor 1 (T4826I mice), a human CGG premutation repeat expansion in the fragile X mental retardation gene 1 (CGG mice), or both mutations (DM mice). Congenic wildtype (WT) mice were used as controls. There were dose-dependent effects of PCB exposure on cytokine concentrations in the serum but not hippocampus. Differential effects of genotype were observed in the serum and hippocampus. Hippocampal cytokines were consistently elevated in T4826I mice and also in WT animals for some cytokines compared to CGG and DM mice, while serum cytokines were usually elevated in the mutant genotypes compared to the WT group. Males had elevated levels of 19 cytokines in the serum and 4 in the hippocampus compared to females, but there were also interactions between sex and genotype for 7 hippocampal cytokines. Only the chemokine CCL5 in the serum showed an interaction between PCB dose, genotype, and sex. Collectively, these findings indicate differential influences of PCB exposure and genotype on cytokine levels in serum and hippocampal tissue of weanling mice. These results suggest that developmental PCB exposure has chronic effects on baseline serum, but not hippocampal, cytokine levels in juvenile mice.