Bisphenol A at concentrations relevant to human exposure enhances histamine and cysteinyl leukotriene release from bone marrow-derived mast cells

Abstract

Bisphenol A (BPA), a monomer of polycarbonate plastics and epoxide resin, acts as an endocrine-active compound and has been shown to enhance the inflammatory response to allergen challenge. Previous reports in rodents have demonstrated that perinatal BPA exposure alters airway inflammation following sensitization and challenge to ovalbumin in juvenile and adult offspring. Additionally, a high concentration of BPA has been shown to enhance mediator release in mast cell lines. This study aimed to determine if short-term BPA exposure, at levels relevant to human exposure, enhances mast cell release of histamine and cysteinyl leukotrienes (CysLTs). Primary murine bone marrow-derived mast cells (BMMC) produced from the femurs of female C57BL/6 mice were stimulated with BPA or estradiol (E2) in vitro. It was observed that both BPA and E2 increased BMMC histamine release over a range of nanomolar concentrations (1–1000?nM). The estrogen receptor (ER) antagonist ICI 182,780 partially blocked the ability of E2, but not BPA, to elevate histamine release. BPA also increased CysLT release, which was not abrogated by ER inhibition. It was also observed that the ability of BPA to enhance histamine and CysLT release was inhibited by blocking the extracellular signal-regulated kinase (ERK) pathway with U0126 or by chelating extracellular calcium (Ca²⁺) using EGTA. In summary, these experiments are the first to demonstrate that acute BPA exposure enhances mast cell histamine and CysLT release in vitro—an effect that is not dependent on an ER-mediated mechanism. Instead, BPA-induced mast cell histamine and CysLT release may be mediated, in part, by the ERK pathway and extracellular Ca²⁺ concentrations. These data suggest that exposure to BPA at levels relevant to human exposure may provoke an acute inflammatory response in atopic individuals via enhanced mast cell activation.     

Epigenetic responses following maternal dietary exposure to physiologically relevant levels of bisphenol A

Animal studies have linked perinatal bisphenol A (BPA) exposure to altered DNA methylation, but little attention is given to analyzing multiple physiologically relevant doses. Utilizing the viable yellow agouti (A^vy) mouse, we examine the effects of developmental exposure through maternal diet to 50 ng BPA/kg (n = 14 litters), 50 μg BPA/kg (n = 9 litters), or 50 mg BPA/kg (n = 13 litters) on global and candidate gene methylation at postnatal day 22. Global methylation analysis reveals hypermethylation in tail tissue of a/a and A^vy/a offspring across all dose groups compared with controls (n = 11 litters; P < 0.02). Analysis of coat color phenotype replicates previous work showing that the distribution of 50 mg BPA/kg A^vy/a offspring shifts toward yellow (P = 0.006) by decreasing DNA methylation in the retrotransposon upstream of the Agouti gene (P = 0.03). Maternal exposure to 50 μg or 50 ng BPA/kg, however, results in altered coat color distributions in comparison with control (P = 0.04 and 0.02), but no DNA methylation effects at the Agouti gene are noted. DNA methylation at the CDK5 activator‐binding protein (Cabp^IAP) metastable epiallele shows hypermethylation in the 50 μg BPA/kg offspring, compared with controls (P = 0.02). Comparison of exposed mouse liver BPA levels to human fetal liver BPA levels indicates that the three experimental exposures are physiologically relevant. Thus, perinatal BPA exposure affects offspring phenotype and epigenetic regulation across multiple doses, indicating the need to evaluate dose effects in human clinical and population studies. Environ. Mol. Mutagen. 2012. © 2012 Wiley Periodicals, Inc.     

Epigenome‐wide DNA methylation analysis implicates neuronal and inflammatory signaling pathways in adult murine hepatic tumorigenesis following perinatal exposure to bisphenol A

Developmental exposure to the endocrine‐active compound bisphenol A (BPA) has been linked to epigenotoxic and potential carcinogenic effects in rodent liver, prostate, and mammary glands. A dose‐dependent increase in hepatic tumors in 10‐month mice perinatally exposed to one of three doses of BPA (50 ng, 50 µg, or 50 mg BPA/kg chow) was previously reported. These tumors represent early‐onset disease and lack classical sexual dimorphism in incidence. Here, adult epigenome‐wide liver DNA methylation profiles to identify gene promoters associated with perinatal BPA exposure and disease in 10‐month mice with and without liver tumors were investigated. Mice with hepatic tumors showed 12,822 (1.8%) probes with differential methylation as compared with non‐tumor animals, of which 8,656 (67.5%) were hypomethylated. A significant enrichment of differential methylation in Gene Ontology (GO) terms and biological processes related to morphogenesis and development, and epigenomic alteration were observed. Pathway enrichment revealed a predominance of hypermethylated neuronal signaling pathways linked to energy regulation and metabolic function, supporting metabolic consequences in the liver via BPA‐induced disruption of neuronal signaling pathways. Hypothesis‐driven pathway analysis revealed mouse and human genes linked to BPA exposure related to intracellular Jak/STAT and MAPK signaling pathways. Taken together, these findings are indicators of the relevance of the hepatic tumor phenotype seen in BPA‐exposed mice to human health. This work demonstrated that epigenome‐wide discovery experiments in animal models were effective tools for identification and understanding of paralagous epimutations salient to human disease. Environ. Mol. Mutagen. 57:435–446, 2016. © 2016 Wiley Periodicals, Inc.     

Low dose bisphenol A impairs spermatogenesis by suppressing reproductive hormone production and promoting germ cell apoptosis in adult rats

Bisphenol A (BPA), an estrogenic chemical, has been shown to reduce sperm count; however, the underlying mechanisms remain unknown. Herein, we show that oral administration of BPA (2 µg/kg) for consecutive 14 days in adult rats (BPA rats) significantly reduced the sperm count and the number of germ cells compared to controls. The serum levels of testosterone and follicle-stimulating hormone (FSH), as well as the level of GnRH mRNA in BPA rats were lower than those of control rats. Testosterone treatment could partially rescue the reduction of germ cells in BPA rats. Notably, the number of apoptotic germ cells was significantly increased in BPA rats, which was insensitive to testosterone. Furthermore, the levels of Fas, FasL and caspase-3 mRNA in the testicle of BPA rats were increased in comparison with controls. These results indicate that exposure to a low dose of BPA impairs spermatogenesis through decreasing reproductive hormones and activating the Fas/FasL signaling pathway.     

Bisphenol A (BPA) aggravates multiple low-dose streptozotocin-induced Type 1 diabetes in C57BL/6 mice

Type 1 diabetes (T1D) is a T-cell-mediated autoimmune disorder characterized by destruction of insulin-producing pancreatic β-cells. Whereas epidemiological data implicate environmental factors in the increasing incidence of T1D, their identity remains unknown. Though exposure to bisphenol A (BPA) has been associated with several disorders, no epidemiologic evidence has linked BPA exposure and T1D. The goal of this study was to elucidate diabetogenic potentials of BPA and underlying mechanisms in the context of T-cell immunity, in a multiple low-dose streptozotocin (MLDSTZ)-induced autoimmune mouse T1D model. C57BL/6 mice were orally exposed to 1 or 10?mg BPA/L starting at 4 wk of age; diabetes was induced at 9 wk of age with STZ. T-cell composition, function, and insulitis levels were studied at Days 11 and 50 during diabetes development (i.e. post-first STZ injection). Results showed both BPA doses increased diabetes incidence and affected T-cell immunity. However, mechanisms of diabetogenic action appeared divergent based on dose. Low-dose BPA fits a profile of an agent that exhibits pro-diabetogenic effects via T-cell immunomodulation in the early stages of disease development, i.e. decreases in splenic T-cell subpopulations [especially CD4⁺ T-cells] along with a trend in elevation of splenic T-cell formation of pro-inflammatory cytokines (IFN-γ, TNF-α, and IL-6). In contrast, high-dose BPA did not affect T-cell populations and led to decreased levels of IFN-γ and TNF-α. Both treatments did not affect insulitis levels at the disease early stage, but aggravated it later on. By the study end, besides decreasing T-cell proliferative capacity, low-dose BPA did not affect other T-cell-related parameters, including cytokine secretion, comparable to the effects of high-dose BPA. In conclusion, this study confirmed BPA as a potential diabetogenic compound with immunomodulatory mechanisms of action – in the context of T-cell immunity – that seemed to be dose dependent in the early immunopathogenesis of a MLDSTZ-induced model of T1D.     

Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway

BackgroundCellular oxidative stress is an important factor in asthma and is thought to be the principle mechanism by which oxidant pollutants such as ozone and particulates mediate their pro-inflammatory effects. Endogenous Phase II enzymes abrogate oxidative stress through the scavenging of reactive oxygen species and metabolism of reactive chemicals.ObjectiveWe conducted a placebo-controlled dose escalation trial to investigate the in vivo effects of sulforaphane, a naturally occurring potent inducer of Phase II enzymes, on the expression of glutathione-s-transferase M1 (GSTM1), glutathione-s-transferase P1 (GSTP1), NADPH quinone oxidoreductase (NQO1), and hemoxygenase-1 (HO-1) in the upper airway of human subjects.MethodsStudy subjects consumed oral sulforaphane doses contained in a standardized broccoli sprout homogenate (BSH). RNA expression for selected Phase II enzymes was measured in nasal lavage cells by RT-PCR before and after sulforaphane dosing.ResultsAll subjects tolerated oral sulforaphane dosing without significant adverse events. Increased Phase II enzyme expression in nasal lavage cells occurred in a dose-dependent manner with maximal enzyme induction observed at the highest dose of 200 g broccoli sprouts prepared as BSH. Significant increases were seen in all sentinel Phase II enzymes RNA expression compared to baseline. Phase II enzyme induction was not seen with ingestion of non-sulforaphane containing alfalfa sprouts.ConclusionOral sulforaphane safely and effectively induces mucosal Phase II enzyme expression in the upper airway of human subjects. This study demonstrates the potential of antioxidant Phase II enzymes induction in the human airway as a strategy to reduce the inflammatory effects of oxidative stress.Clinical implicationsThis study demonstrates the potential of enhancement of Phase II enzyme expression as a novel therapeutic strategy for oxidant induced airway disease.Capsule summaryA placebo-controlled dose escalation trial demonstrated that naturally occurring sulforaphane from broccoli sprouts can induce a potent increase in antioxidant Phase II enzymes in airway cells.     

Maternal bisphenol a exposure during pregnancy and its association with adipokines in Mexican‐American children

Bisphenol A (BPA) is a high volume production chemical that has been detected in 93% of the United States population. It is thought to have endocrine disrupting activity but human data are limited. In this study, we examined whether prenatal or concurrent urinary BPA concentrations are associated with key metabolism‐related hormones, adiponectin and leptin (adipokines), in 9‐year‐old children. For this analysis, we used 188 mother‐child pairs from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) prospective study. BPA was measured in urinary spot samples during early (12.6 ± 3.9 weeks gestation) and late (26.3 ± 2.5 weeks gestation) pregnancy and in 9‐year‐old children. We found that BPA concentrations during late pregnancy were associated with increased plasma leptin in boys (β = 0.06, P = 0.01), controlling for maternal prepregnancy body mass index (BMI), pregnancy soda consumption, and smoking, years in US prior to pregnancy, maternal education, household poverty status, child BMI and child soda, fast food and sweet snack consumption at 9 years. Additionally, we found that BPA concentrations during early pregnancy are directly associated with plasma adiponectin levels in girls (β = 3.71, P = 0.03). However, we did not find any significant relationships between concurrent BPA concentrations and 9‐year child adiponectin or leptin. Overall, our data suggest that prenatal BPA concentrations may influence adipokine levels in 9‐year‐old children. Environ. Mol. Mutagen. 54:621–628, 2013. © 2013 Wiley Periodicals, Inc.     

Enhanced efficacy of the engineered antimicrobial peptide WLBU2 via direct airway delivery in a murine model of Pseudomonas aeruginosa pneumonia

ObjectivesPseudomonas aeruginosa is a common cause of pneumonia in patients with cystic fibrosis with the property to generate multidrug resistance against clinically used antibiotics. Antimicrobial peptides (AMPs) are a diverse group of effector molecules of the innate immune system that protect the host against pathogens. However, the lack of activity in common biological matrices has hampered efforts towards clinical development. In this study, we evaluated the therapeutic potential of the engineered AMP WLBU2 via direct airway delivery in a murine model of P. aeruginosa infection.MethodsThe human AMPs LL37 and WLBU2 were compared for (i) antibiofilm activity using P. aeruginosa on polarized human bronchial epithelial cells, and (ii) efficacy in P. aeruginosa pneumonia in mice using intratracheal instillation of bacteria and AMPs.ResultsWLBU2 (16 μM) prevents biofilm formation by up to 3-log compared with 1-log reduction by LL37. With a single dose of 1 μg (0.05 mg/kg) delivered intratracheally, the initial effect of LL37 was moderate and transitory, as bacterial load and inflammatory cytokines increased at 24 h with observed signs of disease such as lethargy and hypothermia, consistent with moribund state requiring euthanasia. In sharp contrast, WLBU2 reduced bacterial burden (by 2 logs) and bacteria-induced inflammation (leucocytic infiltrates, cytokine and chemokine gene expression) at 6 h and 24 h post-exposure, with no observed signs of disease or host toxicity.ConclusionThese promising results now establish a much lower minimum therapeutic dose of WLBU2 (a net gain of 80-fold) compared with the previously reported 4 mg/kg systemic minimum therapeutic dose, with significant implications for clinical development.     

Adipogenic Effects of a Combination of the Endocrine-Disrupting Compounds Bisphenol A,Diethylhexylphthalate, and Tributyltin

ObjectiveThe food contaminants bisphenol A (BPA), diethylhexylphthalate (DEHP), and tributyltin (TBT) are potent endocrine-disrupting compounds (EDC) known to interfere with adipogenesis. EDC usually act in mixtures and not as single compounds. The aim of this study was to investigate the effects of a simultaneous exposure of BPA, DEHP, and TBT on mesenchymal stem cell differentiation into adipocytes.MethodsMultipotent murine mesenchymal stem cells (C3H10T1/2) were exposed to EDC mixtures in high concentrations, i.e. MIX-high (10 µmol/l BPA, 100 µmol/l DEHP, 100 nmol/l TBT), and in environmentally relevant concentrations, i.e. MIX-low (10 nmol/l BPA, 100 nmol/l DEHP, 1 nmol/l TBT). The exposure was performed either for the entire culture time (0-12 days) or at distinct stages of adipogenic differentiation. At day 12 of cell culture, the amount of adipocytes, triglyceride content (TG), and adipogenic marker gene expression were analyzed.ResultsMIX-high increased the development of adipocytes and the expression of adipogenic marker genes independently of the exposure window. The total TG amount was not increased. The low-concentrated EDC mixture had no obvious impact on adipogenesis.ConclusionIn EDC mixtures, the adipogenic effect of TBT and DEHP predominates single effects of BPA. Mixture effects of EDC are not deducible from single compound experiments.Key Words: Endocrine-disrupting compounds, EDC, Peroxisome proliferator-activated receptor γ, PPARγ, Adipogenesis, Mesenchymal stem cells, MSC     

Contributions of early adversity to pro-inflammatory phenotype in infancy: the buffer provided by attachment security

Adversity early in life is associated with systemic inflammation by adolescence and beyond. At present, few studies have investigated the associations between different forms of adversity and inflammation during infancy, making it difficult to specify the origins of disease vulnerability. This study examined the association between multiple forms of early adversity – socioeconomic status disadvantage, familial stress, maternal depression, and security of attachment – and individual differences in a composite measure of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and tumor necrosis factor-alpha) and the inflammatory protein C-reactive protein that were collected via saliva when (n = 49) children were 17 months old. In addition to gauging the direct effects of adversity, we also tested the hypothesis that infants’ attachment relationship with their mother might buffer infants against the immunologic effects of early adversity. Results show that familial stress, maternal depression, and security of attachment were directly associated with infant salivary inflammation and that attachment status moderated the effect of maternal depression. The findings suggest that exposure to certain forms of adversity very early in life may engender a pro-inflammatory phenotype with possible life-long implications for health.     

Induction of oxidative stress by bisphenol A and its pleiotropic effects

Bisphenol A (BPA) has become a target of intense public scrutiny since concerns about its association with human diseases such as obesity, diabetes, reproductive disorders, and cancer have emerged. BPA is a highly prevalent chemical in consumer products, and human exposure is thought to be ubiquitous. Numerous studies have demonstrated its endocrine disrupting properties and attributed exposure with cytotoxic, genotoxic, and carcinogenic effects; however, the results of these studies are still highly debated and a consensus about BPA's safety and its role in human disease has not been reached. One of the contributing factors is a lack of molecular mechanisms or modes of action that explain the diverse and pleiotropic effects observed after BPA exposure. The increase in BPA research seen over the last ten years has resulted in more studies that examine molecular mechanisms and revealed links between BPA‐induced oxidative stress and human disease. Here, a review of the current literature examining BPA exposure and the induction of reactive oxygen species (ROS) or oxidative stress will be provided to examine the landscape of the current BPA literature and provide a framework for understanding how induction of oxidative stress by BPA may contribute to the pleiotropic effects observed after exposure. Environ. Mol. Mutagen. 58:60–71, 2017. © 2017 Wiley Periodicals, Inc.     

Protection of pigs against 'in contact' challenge with classical swine fever following oral or subcutaneous vaccination with a recombinant porcine adenovirus

A recombinant porcine adenovirus expressing the classical swine fever virus (CSFV) gp55 gene (rPAdV-gp55) was administered to commercially available outbred pigs via the subcutaneous or oral route and their susceptibility to 'in contact' challenge with classical swine fever determined. Animals vaccinated subcutaneously with a single dose of recombinant vaccine and challenged by 'in contact' exposure were protected from disease, whereas pigs given an equivalent single oral dose did not survive challenge. However, pigs given two oral doses of rPAdV-gp55, 22 days apart, were completely protected from disease. In addition, two doses of rPAdV-gp55 given subcutaneously was shown to boost CSFV neutralising antibody compared with a single dose, but neither a single dose nor two doses given orally induced detectable neutralising antibody responses.     

Pulmonary eosinophilia correlates with allergen deposition to the lower respiratory tract in a mouse model of asthma

Background Eosinophilic infiltration into the airways is frequently associated with allergic asthma; however, the role of antigen deposition in mediating this phenomenon has not been studied in detail.
Objective Using a murine model of ovalbumin (OVA) allergy, we examined how differential deposition of OVA during antigen challenge affects pulmonary eosinophilia, immune response and airway hyper-reactivity (AHR).
Methods Differential allergen deposition to the upper respiratory tract (URT) alone or combined upper and lower respiratory tract (ULRT) was accomplished by administering OVA intranasally to either anaesthetized or unanaesthetized mice, respectively. BALB/c mice (6–7 weeks old) were sensitized with OVA–alum via the intraperitoneal route, and then challenged intranasally using OVA, with or without anaesthesia. AHR, enumeration of inflammatory cells and quantitative measurement of inflammatory cytokines and chemokines in bronchoalveolar lavage fluid (BALF), lung histopathology and immune responses were subsequently assessed.
Results In sensitized animals challenged via the ULRT route, a profound eosinophilia and goblet cell hyperplasia was observed in lung tissue. Conversely, sensitized mice receiving an identical challenge dose via the URT route alone exhibited only negligible levels of inflammation. Interestingly, AHR and OVA-specific IgG₁ and IgE systemic responses were comparable between the two groups.
Conclusion This study indicates that direct exposure of allergen in the deep lung is highly correlated with airway eosinophilia and lung inflammation, but does not correlate with AHR or immune response.     

Determination of bisphenol A concentrations in human biological fluids reveals significant early prenatal exposure

BACKGROUND: There is broad human exposure to bisphenol A (BPA), an estrogenic endocrine-disrupting chemical widely used for the production of plastic products. BPA is reported to affect preimplantation embryos or fetuses and alter their postnatal development at doses typically found in the environment. We measured contamination of BPA in various kinds of human biological fluids by a novel enzyme-linked immunosorbent assay. METHODS: Blood samples were obtained from healthy premenopausal women, women with early and full-term pregnancy, and umbilical cord at full-term delivery. Ovarian follicular fluids obtained during IVF procedures and amniotic fluids obtained at mid-term and full-term pregnancy were also subject to BPA measurements. RESULTS: BPA was present in serum and follicular fluid at approximately 1-2 ng/ml, as well as in fetal serum and full-term amniotic fluid, confirming passage through the placenta. Surprisingly, an approximately 5-fold higher concentration, 8.3 +/- 8.7 ng/ml, was revealed in amniotic fluid at 15-18 weeks gestation, compared with other fluids. CONCLUSION: These results suggest accumulation of BPA in early fetuses and significant exposure during the prenatal period, which must be considered in evaluating the potential for human exposure to endocrine-disrupting chemicals.     

Periodontitis: a newly identified comorbidity in psoriasis and psoriatic arthritis

ABSTRACT

Introduction: Psoriasis is a chronic autoimmune skin disease with strong genetic background and environmental triggers. Patients with psoriasis and psoriatic arthritis are at greater risk of developing other chronic and potentially severe comorbidities, such as psoriatic arthritis, hyperlipidemia, type 2 diabetes mellitus, obesity, metabolic syndrome, cardiovascular diseases or depression. Recently, accumulating epidemiologic, genetic and pathogenetic evidence indicates that psoriasis is also associated with periodontitis, a chronic progressive inflammatory disease, which may result in tooth loss without early and adequate therapy.

Areas covered: In this review article we summarize and discuss in detail the available epidemiologic, genetic, microbiological and immunological links between psoriasis and periodontitis.

Expert opinion: Periodontitis, via the immunomodulatory effect of the oral microbiota, may play both a direct and indirect role in the development or exacerbation of psoriasis, and may influence the efficacy of antipsoriatic therapy. These new findings indicate a need for increased awareness, early recognition and focus on prevention of periodontitis for patients with psoriasis.     

Anti-inflammatory effects of embelin in A549 cells and human asthmatic airway epithelial tissues

Objective: Allergic asthma is the most common type in asthma, which is defined as a chronic inflammatory disease of the lung. In this study, we investigated whether embelin (Emb), the major component of Ardisia japonica BL. (AJB), exhibits anti-inflammatory effects on allergic asthma via inhibition of NF-κB activity using A549 cells and asthmatic airway epithelial tissues.

Methods: Inflammation was induced in A549 cells, a human airway epithelial cell line, by IL-1β (10?ng/ml) treatment for 4?h. The effects of Emb on NF-κB activity and COX-2 protein expression in inflamed airway epithelial cells and human asthmatic airway epithelial tissues were analyzed via western blot. The secretion levels of NF-κB-mediated cytokines/chemokines, including IL-4, 6, 9, 13, TNF-α and eotaxin, were measured by a multiplex assay.

Results: Emb significantly blocked NF-κB activity in IL-1β-treated A549 cells and human asthmatic airway epithelial tissues. COX-2 expression was also reduced in both IL-1β-treated A549 cells and asthmatic tissues Emb application. Emb significantly reduced the secretion of IL-4, IL-6 and eotaxin in human asthmatic airway epithelial tissues by inhibiting activity of NF-κB.

Conclusions: The results of this study suggest that Emb may be used as an anti-inflammatory agent via inhibition of NF-κB and related cytokines.