Induction and persistence of radiation-induced DNA damage is more pronounced in young animals than in old animals

Younger individuals are more prone to develop cancer upon ionizing radiation (IR) exposure. Radiation-induced tumors are associated with inefficient repair of IR-induced DNA damage and genome instability. Phosphorylation of histone H2AX (γ-H2AX) is the initial event in repair of IR-induced DNA damage on the chromatin flanking the DNA strand breaks. This step is crucially important for the repair of DNA strand breaks and for the maintenance of genome stability. We studied the molecular underpinnings of the age-related IR effects using an animal model. By assaying for IR-induced γ-H2AX foci we analyzed the induction and repair of the DNA strand breaks in spleen, thymus, liver, lung, kidney, cerebellum, hippocampus, frontal cortex and olfactory bulb of 7, 14, 24, 30 and 45 days old male and female mice as a function of age. We demonstrate that tissues of younger animals are much more susceptible to IR-induced DNA damage. Younger animals exhibited higher levels of γ-H2AX formation which partially correlated with cellular proliferation and expression of DNA repair proteins. Induction and persistence of γ-H2AX foci was the highest in lymphoid organs (thymus and spleen) of 7 and 14 day old mice. The lowest focal induction was seen in lung and brain of young animals. The mechanisms of cell and tissue-specificity of in vivo IR responses need to be further dissected. This study provides a roadmap for the future analyses of DNA damage and repair induction in young individuals

Molecular mechanisms of radiation-induced bystander effects in vivo

xiii, 208 leaves : ill. ; 29 cm.Ionizing radiation (IR), along with being an important diagnostic and treatment modality, is a potent tumor-causing agent, and the risk of secondary radiation treatment-related cancers is a growing clinical problem. Now some studies propose to link secondary radiation-induced cancers to an enigmatic phenomenon of bystander effects, whereby the exposed cells send signal damage and distress to their naïve neighbors and result in genome destabilization and carcinogenesis. Yet, no data existed on the bystander effects in an organ other than an exposed one. With this in mind, we focused on the analysis of existence and mechanisms of radiation-induced bystander effects in vivo. We have found that bystander effects occur in vivo in distant skin and spleen following half-body or cranial irradiation. These bystander effects resulted in elevated DNA damage, profound dysregulation of epigenetic machinery, and pronounced alterations in apoptosis, proliferation and gene expression. Bystander effects also exhibited persistency and sex specificity. The results obtained while using the animal model systems can potentially be extrapolated to different animals and humans

Hepatotoxicity of a Cannabidiol-rich cannabis extract in the mouse model

© 2019 Xide Ye et al. Gastrodia elata Blume belongs to the Orchidaceae family. G. elata is often processed when used in traditional Chinese medicine (TCM). In the current study, a traditional processing method, known as Jianchang Bang, was applied. Steamed and dried (S&D) G. elata was processed with ginger juice for up to 5 days (GEP5D). An UHPLC-MS/MS combined with a chemometric method was developed for the analysis of processed G. elata along with the raw material as well as steamed and dried G. elata. As a result, the primary marker compounds were identified with the aid of TOF-MS and MS/MS analyses. Compared with the raw material of G. elata with GEP5D, three new parishin-type compounds were identified according to their retention time, accurate mass, and fragmentation patterns. The chromatographic peak areas for marker compounds, including S-(gastrodin)-glutathione, S-(4-hydroxybenzylamine)-glutathione, and parishin-type compounds, changed significantly. This result indicated that by applying the Jianchang Bang method, changes in chemical composition in G. elata contents were observed. The study also demonstrated that chemometric analysis is helpful in understanding the processing mechanism and will provide scientific support for the clinical application of G. elata

Epigenetic Alterations in Liver of C57BL/6J Mice after Short-Term Inhalational Exposure to 1,3-Butadiene

Background1,3-Butadiene (BD) is a high-volume industrial chemical and a known human carcinogen. The main mode of BD carcinogenicity is thought to involve formation of genotoxic epoxides.ObjectivesIn this study we tested the hypothesis that BD may be epigenotoxic (i.e., cause changes in DNA and histone methylation) and explored the possible molecular mechanisms for the epigenetic changes.Methods and ResultsWe administered BD (6.25 and 625 ppm) to C57BL/6J male mice by inhalation for 2 weeks (6 hr/day, 5 days a week) and then examined liver tissue from these mice for signs of toxicity using histopathology and gene expression analyses. We observed no changes in mice exposed to 6.25 ppm BD, but glycogen depletion and dysregulation of hepatotoxicity biomarker genes were observed in mice exposed to 625 ppm BD. We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation. In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3–9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks. Although the epigenetic effects were most pronounced in the 625-ppm exposure group, some effects were evident in mice exposed to 6.25 ppm BD.ConclusionsThis study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity

Safety and molecular-toxicological implications of cannabidiol-rich cannabis extract and methylsulfonylmethane co-administration

© 2020 by the authors. Cannabidiol (CBD) is a biologically active, non-psychotropic component of Cannabis sativa whose popularity has grown exponentially in recent years. Besides a wealth of potential health benefits, ingestion of CBD poses risks for a number of side effects, of which hepatotoxicity and CBD/herb-drug interactions are of particular concern. Here, we investigated the interaction potential between the cannabidiol-rich cannabis extract (CRCE) and methylsulfonylmethane (MSM), a popular dietary supplement, in the mouse model. For this purpose, 8-week-old male C57BL6/J mice received MSM-containing water (80 mg/100 mL) ad libitum for 17 days. During the last three days of treatment, mice received three doses of CRCE administered in sesame oil via oral gavage (123 mg/kg/day). Administration of MSM alone did not result in any evidence of liver toxicity and did not induce expression of mouse cytochrome P450 (CYP) enzymes. Administration of CRCE did produce significant (p \u3c 0.05) increases in Cyp1a2, Cyp2b10, Cyp2c29, Cyp3a4, Cyp3a11, Cyp2c65, and Cyp2c66 messenger RNA, however, this effect was not amplified by MSM/CRCE cotreatment. Similarly, no evidence of liver toxicity was observed in MSM/CRCE dosed mice. In conclusion, short-term MSM/CRCE co-administration did not demonstrate any evidence of hepatotoxicity in the mouse model

Epigenetic Mechanisms of Mouse Interstrain Variability in Genotoxicity of the Environmental Toxicant 1,3-Butadiene

1,3-Butadiene (BD) is a common environmental contaminant classified as “carcinogenic to humans.” Formation of BD-induced DNA adducts plays a major role in its carcinogenicity. BD is also an epigenotoxic agent (i.e., it affects DNA and histone methylation in the liver). We used a panel of genetically diverse inbred mice (NOD/LtJ, CAST/EiJ, A/J, WSB/EiJ, PWK/PhJ, C57BL/6J, and 129S1/SvImJ) to assess whether BD-induced genotoxic and epigenotoxic events may be subject to interstrain differences. Mice (male, 7 weeks) were exposed via inhalation to 0 or 625 ppm BD for 6 h/day and 5 days/week for 2 weeks and liver BD-DNA adducts, epigenetic alterations, and liver toxicity were assessed. N-7-(2,3,4-trihydroxybut-1-yl)-guanine adducts were detected in all strains after exposure, yet BD-induced DNA damage in CAST/EiJ mice was two to three times lower. Epigenetic effects of BD were most prominent in C57BL/6J mice where loss of global DNA methylation and loss of trimethylation of histone H3 lysine 9, histone H3 lysine 27, and histone H4 lysine 20, accompanied by dysregulation of liver gene expression indicative of hepatotoxicity, were found. Interestingly, we observed an increase in histone methylation in the absence of changes in gene expression and DNA methylation in CAST/EiJ strain. We hypothesized that mitigated genotoxicity of BD in CAST/EiJ mice may be due to chromatin condensation. Indeed, we show that in response to BD exposure, chromatin condensation occurs in CAST/EiJ, whereas the opposite effect is observed in C57BL/6J mice. These findings demonstrate that interstrain susceptibility to genotoxicity by a well-known environmental carcinogen may be due to strain-specific epigenetic events in response to the exposure

Decaffeinated green tea extract does not elicit hepatotoxic effects and modulates the gut microbiome in lean B6C3F\u3csub\u3e1\u3c/sub\u3e mice

© 2019 The Author(s) The aim of this study is the development of validated HPTLC method for the quantification of vitexin from Passiflora foetida commercial herbal formulations. The developed method was validated, in accordance with ICH guidelines for precision, accuracy, specificity and robustness. The plate was developed using ethyl acetate:methanol:water:formic acid 30:4:2:1(%, v/v/v/v) on 20 × 10 cm glass coated silica gel 60 F254 plates and the developed plate was scanned and quantified densitometrically at λ = 340 nm. Linear regression analysis revealed a good linear relationship between peak area and amount of vitexin in the range of 100–700 ng/spot. The amount of vitexin in nine commercial herbal formulations was successfully quantified by the developed HPTLC method. The developed and validated high performance thin layer chromatographic method offers a new sensitive and reliable tool for quantification of vitexinin in various herbal formulations containing Passiflora foetida

The aggregatibacter actinomycetemcomitans heat shock protein GroEL interacts directly with human peripheral blood T cells

Heat shock family protein GroEL of Aggregatibacter actinomycetemcomitans (Aa) has antigenic properties. We previously demonstrated that A. actinomycetemcomitans GroEL-like protein affects human CD4 T cells by converting them into IL-10 and IFNg double cytokine producing Tbet+ Th1 cells. The objective of this study was to investigate whether or not AaGroEL communicates with T cells directly. To do this, sorted cells from peripheral blood mononuclear cells were stimulated with AaGroEL for 48 h. Flow cytometry was used to measure soluble and intracellular cytokine expression in the cell cultures and detect TLR2 expression on the surface of T cells. Expression of six different soluble cytokines was evaluated by CBA assay. To determine whether AaGroEL affects CD3+ T cells directly or not, purified CD3+ T cells or CD14+ cells were cultured with AaGroEL separately, and the quantity of soluble cytokine was measured. Results showed that sorted CD3+ cells produced soluble IL-6, TNFα-and IFNγ cytokines. Additionally, the intracellular cytokine staining data showed that AaGroEL-stimulated CD3+ cells were also TNFα-and IFNγ-positive. Moreover, AaGroEL-responsive T cells slightly increased their TLR2 expression. These findings suggest that CD3+ T cells produce cytokines in response to AaGroEL protein without requirements for other cells, such as CD14+ monocytes.Scientific and Technological Research Council of Turkey (TUBITAK 106T417

Paradoxical patterns of sinusoidal obstruction syndrome-like liver injury in aged female CD-1 mice triggered by cannabidiol-rich cannabis extract and acetaminophen co-administration

© 2019 The Authors. Environmental Toxicology published by Wiley Periodicals, Inc. Exposure to environmental contaminants and consumption of a high, saturated fatty diet has been demonstrated to promote precursors for metabolic syndrome (hyperglycemia, hyperinsulinemia, and hypertriglyceridemia). The purpose of this study was to determine if exposure to the most prevalent environmental persistent organic pollutants (POPs) would act as causative agents to promote metabolic syndrome independent of dietary intake. We hypothesized that POPs will activate the advanced glycated end-product (AGE)-and receptor for AGE (RAGE) signaling cascade to promote downstream signaling modulators of cardiovascular remodeling and oxidative stress in the heart. At 5-weeks of age nondiabetic (WT) and diabetic (ob/ob) mice were exposed POPs mixtures by oral gavage twice a week for 6-weeks. At the end of 6-weeks, animals were sacrificed and the hearts were taken for biochemical analysis. Increased activation of the AGE-RAGE signaling cascade via POPs exposure resulted in elevated levels of fibroblast differentiation (α-smooth muscle actin) and RAGE expression indicated maladaptive cardiac remodeling. Conversely, the observed decreased superoxide dismutase-1 and -2 (SOD-1 and SOD-2) expression may exacerbate the adverse changes occurring as a result of POPs treatment to reduce innate cardioprotective mechanisms. In comparison, ventricular collagen levels were decreased in mice exposed to POPs. In conclusion, exposure to organic environmental pollutants may intensify oxidative and inflammatory stressors to overwhelm protective mechanisms allowing for adverse cardiac remodeling

Importance of investigating epigenetic alterations for industry and regulators: An appraisal of current efforts by the Health and Environmental Sciences Institute

AbstractRecent technological advances have led to rapid progress in the characterization of epigenetic modifications that control gene expression in a generally heritable way, and are likely involved in defining cellular phenotypes, developmental stages and disease status from one generation to the next. On November 18, 2013, the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) held a symposium entitled “Advances in Assessing Adverse Epigenetic Effects of Drugs and Chemicals” in Washington, D.C. The goal of the symposium was to identify gaps in knowledge and highlight promising areas of progress that represent opportunities to utilize epigenomic profiling for risk assessment of drugs and chemicals. Epigenomic profiling has the potential to provide mechanistic information in toxicological safety assessments; this is especially relevant for the evaluation of carcinogenic or teratogenic potential and also for drugs that directly target epigenetic modifiers, like DNA methyltransferases or histone modifying enzymes. Furthermore, it can serve as an endpoint or marker for hazard characterization in chemical safety assessment. The assessment of epigenetic effects may also be approached with new model systems that could directly assess transgenerational effects or potentially sensitive stem cell populations. These would enhance the range of safety assessment tools for evaluating xenobiotics that perturb the epigenome. Here we provide a brief synopsis of the symposium, update findings since that time and then highlight potential directions for future collaborative efforts to incorporate epigenetic profiling into risk assessment