Correlations of Aflatoxin Exposure from Cooking Oil and Dietary Foods During Pregnancy with Birth Weight and Gestational Age at Birth in Guangxi, China.

Background: Cooking oil and dietary foods are easily contaminated by aflatoxins (AFs) in Guangxi, China where low birth weight and preterm birth were prevalent. However, there are no data on AF exposure in pregnant women or their impact on newborn birth outcomes. This study aims to measure the levels and correlations of AFs in cooking oil, estimated dietary intake (EDI) of AFs in dietary foods, and serum AFB1 albumin adducts (AFB1-alb) with newborn birthweight and gestational age at birth. Methods: A prospective study was conducted among 126 pregnant women in Guangxi, China. All recruited women were interviewed for demographic data and behavior and obstetric information and then followed up until giving birth. AF measurements were obtained from cooking oil, dietary foods, maternal serum, and cord blood and the correlations of AF levels with newborn birthweight and gestational age at birth were tested using correlation analysis. Results: The median EDI of AFs in cooking oil was 2.61 ng/kg.bw/day and in dietary foods 2.95 ng/kg.bw/day. High positive correlations among EDI of aflatoxin B1 (AFB1) from cooking oil and dietary foods were found (r > 0.7). Low positive correlations of AFB1-alb in maternal serum and cord blood and both EDI of AFB1 in both cooking oil and dietary foods were shown (r ≈0.3). Significant correlations between AF levels in both cooking oil and dietary foods with birth weight were found, but very low negative correlations (r = - 0.244 ~ -0.285). AFB1 levels in foods, maternal serum and cord blood levels were high in pregnant women with newborn low birth weight and preterm birth. Conclusion: The EDIs of AFB1 from both cooking oil and dietary foods were significantly correlated with AFB1-alb in maternal serum and cord blood. Negative correlations of AFs from cooking oils and foods with newborn birth weight should be paid more attention.

Geniposide reduced oxidative stress-induced apoptosis in HK-2 cell through PI3K/AKT3/FOXO1 by m6A modification.

Exogenous hydrogen peroxide (H2O2) may generate excessive oxidative stress, inducing renal cell apoptosis related with kidney dysfunction. Geniposide (GP) belongs to the iridoid compound with anti-inflammatory, antioxidant and anti-apoptotic effects. This study aimed to observe the intervention effect of GP on H2O2-induced apoptosis in human kidney-2 (HK-2) cells and to explore its potential mechanism in relation to N6-methyladenosine (m6A) RNA methylation. Cell viability, apotosis rate and cell cycle were tested separately after different treatments. The mRNA and protein levels of m6A related enzymes and phosphoinositide 3-kinase (PI3K)/a serine/threonine-specific protein kinase 3 (AKT3)/forkhead boxo 1 (FOXO1) and superoxide dismutase 2 (SOD2) were detected by reverse transcription-quantitative real-time PCR (RT-qPCR) and Western blot. The whole m6A methyltransferase activity and the m6A content were measured by ELISA-like colorimetric methods. The changes of m6A methylation levels of PI3K/AKT3/FOXO1 and SOD2 were determined by methylated RNA immunoprecipitation (MeRIP)-qPCR. Multiple comparisons were performed by ANOVA with Turkey's post hoc test. Exposed to 400 µmol/L H2O2, cells were arrested in G1 phase and the apoptosis rate increased, which were significantly alleviated by GP. Compared with the H2O2 apoptosis group, both the whole m6A RNA methyltransferase activity and the m6A contents were increased due to GP intervention. Besides, the SOD2 protein was increased, while PI3K and FOXO1 decreased. The m6A methylation level of AKT3 was negatively correlated with its protein level. Taken together, GP affects the global m6A methylation microenvironment and regulates the expression of PI3K/AKT3/FOXO1 signaling pathway via m6A modification, alleviating cell cycle arrest and apoptosis caused by oxidative stress in HK-2 cells with a good application prospect.

Metabolism-dependent mutagenicity of two structurally similar tobacco-specific nitrosamines (N-nitrosonornicotine and N-nitrosoanabasine) in human cells, partially different CYPs being activating enzymes.

N-nitrosonornicotine (NNN) and N-nitrosoanabasine (NAB) are both tobacco-specific nitrosamines bearing two heterocyclic amino groups, NAB bearing an extra -CH2- group (conferring a hexa- rather than penta-membered cycle) but with significantly decreased carcinogenicity. However, their activating enzymes and related mutagenicity remain unclear. In this study, the chemical-CYP interaction was analyzed by molecular docking, thus the binding energies and conformations of NNN for human CYP2A6, 2A13, 2B6, 2E1 and 3A4 appeared appropriate as a substrate, so did NAB for human CYP1B1, 2A6, 2A13 and 2E1. The micronucleus test in human hepatoma (HepG2) cells with each compound (62.5-1000 µM) exposing for 48 h (two-cell cycle) was negative, however, pretreatment with bisphenol AF (0.1-100 nM, CYPs inducer) and ethanol (0.2% v:v, CYP2E1 inducer) potentiated micronucleus formation by both compounds, while CITCO (1 µM, CYP2B6 inducer) selectively potentiated that by NNN. In C3A cells (endogenous CYPs enhanced over HepG2) both compounds induced micronucleus, which was abolished by 1-aminobenzotriazole (60 µM, CYPs inhibitor) while unaffected by 8-methoxypsoralen (1 µM, CYP2A inhibitor). Consistently, NNN and NAB induced micronucleus in V79-derived recombinant cell lines expressing human CYP2B6/2E1 and CYP1B1/2E1, respectively, while negative in those expressing other CYPs. By immunofluorescent assay both compounds selectively induced centromere-free micronucleus in C3A cells. In PIG-A assays in HepG2 cells NNN and NAB were weakly positive and simply negative, respectively; however, in C3A cells both compounds significantly induced gene mutations, NNN being slight more potent. Conclusively, both NNN and NAB are mutagenic and clastogenic, depending on metabolic activation by partially different CYP enzymes.

Exploring the Antibacterial Potential and Underlying Mechanisms of Prunella vulgaris L. on Methicillin-Resistant Staphylococcus aureus.

Prunella vulgaris L. (PV) is a widely distributed plant species, known for its versatile applications in both traditional and contemporary medicine, as well as in functional food development. Despite its broad-spectrum antimicrobial utility, the specific mechanism of antibacterial action remains elusive. To fill this knowledge gap, the present study investigated the antibacterial properties of PV extracts against methicillin-resistant Staphylococcus aureus (MRSA) and assessed their mechanistic impact on bacterial cells and cellular functions. The aqueous extract of PV demonstrated greater anti-MRSA activity compared to the ethanolic and methanolic extracts. UPLC-ESI-MS/MS tentatively identified 28 phytochemical components in the aqueous extract of PV. Exposure to an aqueous extract at ½ MIC and MIC for 5 h resulted in a significant release of intracellular nucleic acid (up to 6-fold) and protein (up to 10-fold) into the extracellular environment. Additionally, this treatment caused a notable decline in the activity of several crucial enzymes, including a 41.51% reduction in alkaline phosphatase (AKP), a 45.71% decrease in adenosine triphosphatase (ATPase), and a 48.99% drop in superoxide dismutase (SOD). Furthermore, there was a decrease of 24.17% at ½ MIC and 27.17% at MIC in tricarboxylic acid (TCA) cycle activity and energy transfer. Collectively, these findings indicate that the anti-MRSA properties of PV may stem from its ability to disrupt membrane and cell wall integrity, interfere with enzymatic activity, and impede bacterial cell metabolism and the transmission of information and energy that is essential for bacterial growth, ultimately resulting in bacterial apoptosis. The diverse range of characteristics exhibited by PV positions it as a promising antimicrobial agent with broad applications for enhancing health and improving food safety and quality.

Geniposide alleviated hydrogen peroxide-induced apoptosis of human hepatocytes via altering DNA methylation.

Geniposide (GP) is the homology of medicine and food with bioactive effects of antioxidation and resistance to apoptosis in the liver. It's of great significance to explore the biosafety exposure limits and action mechanisms of GP. This study detected the global DNA methylation microenvironment and the regulation of specific genes in GP against cellular apoptosis induced by hydrogen peroxide (H2O2) of human hepatocyte L-02 cells. The half inhibitory concentration (IC50) of GP on normal L-02 cells was 57.7 mg/mL. GP exerted new epigenetic activity, increased DNMT1, decreased TET1 and TET2 expression, and reversed the demethylation effect to some extent, thereby increasing the overall genomic DNA methylation level at the concentration of 900 µg/mL. GP pretreatment could also adjust the level of P53, Bcl-2 and AKT altered by H2O2, reducing their specific DNA methylation levels in the promoter regions of AKT and Bcl-2 to inhibit apoptosis. Taken together, GP regulates the global DNA methylation level and controls the expression changes of P53, Bcl-2 and AKT, jointly inhibiting the occurrence of apoptosis in human hepatocytes and providing the newly theoretical references for its safety evaluation.

Assessment of the Adverse Health Effects of Aflatoxin Exposure from Unpackaged Peanut Oil in Guangdong, China.

Aflatoxins are liver carcinogens and are common contaminants in unpackaged peanut (UPP) oil. However, the health risks associated with consuming aflatoxins in UPP oil remain unclear. In this study, aflatoxin contamination in 143 UPP oil samples from Guangdong Province were assessed via liquid chromatography-tandem mass spectrometry (LC-MS). We also recruited 168 human subjects, who consumed this oil, to measure their liver functions and lipid metabolism status. Aflatoxin B1 (AFB1) was detected in 79.72% of the UPP oil samples, with levels ranging from 0.02 to 174.13 µg/kg. The average daily human intake of AFB1 from UPP oil was 3.14 ng/kg·bw/day; therefore, the incidence of liver cancer, caused by intake of 1 ng/kg·bw/day AFB1, was estimated to be 5.32 cases out of every 100,000 persons per year. Meanwhile, Hepatitis B virus (HBV) infection and AFB1 exposure exerted a synergistic effect to cause liver dysfunction. In addition, the triglycerides (TG) abnormal rate was statistically significant when using AFB1 to estimate daily intake (EDI) quartile spacing grouping (p = 0.011). In conclusion, high aflatoxin exposure may exacerbate the harmful effects of HBV infection on liver function. Contamination of UPP oil with aflatoxins in Guangdong urgently requires more attention, and public health management of the consumer population is urgently required.

Association between Residential Greenness and Human Microbiota: Evidence from Multiple Countries.

BACKGROUND: Greenness, referring to a measurement of the density of vegetated land (e.g., gardens, parks, grasslands), has been linked with many human health outcomes. However, the evidence on greenness exposure and human microbiota remains limited, inconclusive, drawn from specific regions, and based on only modest sample size. OBJECTIVES: We aimed to study the association between greenness exposure and human microbial diversity and composition in a large sample across 34 countries and regions. METHODS: We explored associations between residential greenness and human microbial alpha-diversity, composition, and genus abundance using data from 34 countries. Greenness exposure was assessed using the normalized difference vegetation index and the enhanced vegetation index mean values in the month before sampling. We used linear regression models to estimate the association between greenness and microbial alpha-diversity and tested the effect modification of age, sex, climate zone, and pet ownership of participants. Differences in microbial composition were tested by permutational multivariate analysis of variance based on Bray-Curtis distance and differential taxa were detected using the DESeq2 R package between two greenness exposure groups split by median values of greenness. RESULTS: We found that higher greenness was significantly associated with greater richness levels in the palm and gut microbiota but decreased evenness in the gut microbiota. Pet ownership and climate zone modified some associations between greenness and alpha-diversity. Palm and gut microbial composition at the genus level also varied by greenness. Higher abundances of the genera Lactobacillus and Bifidobacterium, and lower abundances of the genera Anaerotruncus and Streptococcus, were observed in people with higher greenness levels. DISCUSSION: These findings suggest that residential greenness was associated with microbial richness and composition in the human skin and gut samples, collected across different geographic contexts. Future studies may validate the observed associations and determine whether they correspond to improvements in human health. https://doi.org/10.1289/EHP12186.

Global burden and drivers of hyperglycemia: Estimates and predictions from 1990 to 2050.

Hyperglycemia is a key risk factor for death and disability worldwide. To better inform prevention strategies, we aimed to delineate and predict the temporal, spatial, and demographic patterns in mean fasting plasma glucose (FPG) levels and their related disease burden globally. Based on the Global Burden of Disease Study 2019, we estimated the distributions of mean FPG levels and high FPG-related disease burden by age, sex, year, socioeconomic status (SES), and geographical region from 1990 to 2050. We also investigated the possible associations of demographic, behavioral, dietary, metabolic, and environmental factors with FPG levels and high FPG-related disease burden. In 2019, the global mean FPG level was 5.40 mmol/L (95% uncertainty interval [UI]: 4.86-6.00), and high FPG contributed to 83.0 deaths (95% UI, 64.5-107.1) and 2,104.3 DALYs (95% UI: 1,740.7-2,520.7) per 100,000 people. For both historical (1990-2019) and future (2020-2050) periods, the mean FPG levels and the high FPG-related disease burden increased globally, with greater increases among the middle-aged and elderly, and people in low-to-middle SES countries, relative to their counterparts. Aging, unhealthy lifestyles, elevated body mass index, and lower air temperatures were potential risk factors for high FPG levels and the high FPG-related disease burden. This study demonstrates that high FPG continues to contribute to the global disease burden and is expected to do so for at least the next 30 years. Older people and those living in low-to-middle SES countries should receive more attention in glycemic management health interventions. In addition, effective interventions that target identified risk factors should be adopted to handle the increasingly large disease burden of high FPG.

Hyperoside attenuates Cd-induced kidney injury via inhibiting NLRP3 inflammasome activation and ROS/MAPK/NF-κB signaling pathway in vivo and in vitro.

Cadmium accumulates in the kidney and causes inflammation. The NLRP3 inflammasome has been linked to the pathogenesis of inflammation. Hyperoside (HYP) possesses potent nephroprotective properties against of kidney injury. This study aimed to research the effects and related mechanism of HYP on Cd-induced kidney damage. Wide-type and NLRP3-/- mice were used to determine the role of NLRP3 inflammasome in Cd-induced renal dysfunction. Female C57BL/6 were treated with Cd (50 m,g/L) and HYP (25, 50 mg/kg) for 12 weeks. In vitro experiments, the human renal proximal-tubule epithelial cells (RPTEC/TERT1) were pretreated with HYP (50-200 µM) before exposure to Cd. NLRP3 deficiency attenuated Cd-induced NLRP3 activation, inflammation and kidney injury in mice. HYP treatment significantly alleviated Cd-induced kidney injury by decreasing indexes of kidney function, reducing pro-inflammatory cytokines release, decreasing ROS production and suppressing NLRP3 inflammasome activation. Moreover, treatment with siRNA targeting NLRP3 blocked the anti-inflammatory protective effect of HYP in Cd-treated cells. Additionally, HYP markedly inhibited Cd-induced MAPK/NF-κB pathway stimulation in vitro and in vivo. The findings indicated HYP conferred protection against Cd-induced kidney inflammation via suppression of NLRP3 inflammasome mediated by ROS/MAPK/NF-κB signaling. Our results thus support the notion of developing HYP as promising therapeutic candidate for Cd-induced kidney injury.

Benzene Exposure Leads to Lipodystrophy and Alters Endocrine Activity In Vivo and In Vitro.

Benzene is a ubiquitous pollutant and mainly accumulates in adipose tissue which has important roles in metabolic diseases. The latest studies reported that benzene exposure was associated with many metabolic disorders, while the effect of benzene exposure on adipose tissue remains unclear. We sought to investigate the effect using in vivo and in vitro experiments. Male adult C57BL/6J mice were exposed to benzene at 0, 1, 10 and 100 mg/kg body weight by intragastric gavage for 4 weeks. Mature adipocytes from 3T3-L1 cells were exposed to hydroquinone (HQ) at 0, 1, 5 and 25 µM for 24 hours. Besides the routine hematotoxicity, animal experiments also displayed significant body fat content decrease from 1 mg/kg. Interestingly, the circulating non-esterified fatty acid (NEFA) level increased from the lowest dose (ptrend < 0.05). Subsequent analysis indicated that body fat content decrease may be due to atrophy of white adipose tissue (WAT) upon benzene exposure. The average adipocyte area of WAT decreased significantly even from 1 mg/kg with no significant changes in total number of adipocytes. The percentages of small and large adipocytes in WAT began to significantly increase or decrease from 1 mg/kg (all p < 0.05), respectively. Critical genes involved in lipogenesis and lipolysis were dysregulated, which may account for the disruption of lipid homeostasis. The endocrine function of WAT was also disordered, manifested as significant decrease in adipokine levels, especially the leptin. In vitro cell experiments displayed similar findings in decreased fat content, dysregulated critical lipid metabolism genes, and disturbed endocrine function of adipocytes after HQ treatment. Pearson correlation analysis showed positive correlations between white blood cell (WBC) count with WAT fat content and plasma leptin level (r = 0.330, 0.344, both p < 0.05). This study shed light on the novel aspect that benzene exposure could induce lipodystrophy and disturb endocrine function of WAT, and the altered physiology of WAT might in turn affect benzene-induced hematotoxicity and metabolic disorders. The study provided new insight into understanding benzene-induced toxicity and the relationship between benzene and adipose tissue.

Associations of long-term cadmium exposure with peripheral white blood cell subtype counts and indices in residents of cadmium-polluted areas.

BACKGROUND: Experimental evidence suggests that exposure to cadmium (Cd) could affect immune cells in vivo and in vitro. However, the associations of long-term Cd exposure with white blood cell (WBC) subtype counts and hemogram-derived indices have been rarely investigated. Therefore, we evaluated these relationships in residents of cadmium-polluted areas. METHODS: This cross-sectional study included 431 participants aged 45-75 years without occupational exposure histories from Cd-contaminated areas of southern China. We detected WBC, neutrophil, lymphocyte, and monocyte counts using routine blood tests and calculated neutrophil-lymphocyte ratio (NLR), systemic inflammation response index (SIRI), and lymphocyte-monocyte ratio (LMR). Urinary Cd (U-Cd) was measured with inductively coupled plasma mass spectrometry and adjusted for creatinine. To evaluate the associations of U-Cd with peripheral WBC subtype counts and indices, we performed multivariate linear regression, logistic regression and subgroup analyses using U-Cd categorized into quartiles. RESULTS: In models adjusted for all potential confounders, U-Cd was negatively associated with WBC, neutrophil, and monocyte counts in Q2, compared with Q1 of U-Cd (p < 0.05). A similar relationship was observed between U-Cd and NLR and SIRI, whereas the corresponding association for LMR was positive (p < 0.05). In subgroup analyses, U-Cd was negatively associated with neutrophil count, except for never smokers, after full adjustment. CONCLUSIONS: U-Cd was negatively associated with WBC count, neutrophil count, monocyte count, NLR, and SIRI, and positively associated with LMR. Therefore, neutrophil count could be a potential indicator of long-term Cd exposure-associated immunosuppressive effect.

Cadmium chloride-induced apoptosis of HK-2 cells via interfering with mitochondrial respiratory chain.

Cadmium could induce cell apoptosis, probably related to the dysfunction of the mitochondrial respiratory chain. The human renal proximal tubule (HK-2) was used to explore the mechanism of mitochondrial respiratory chain dysfunction during apoptosis induced by cadmium chloride (CdCl2). Cell viability was evaluated by cell proliferation assay and different concentrations of 60, 80 and 100 µM were selected to evaluate the mitochondrial toxicity of CdCl2 respectively. Under the CdCl2 treatment for 24 h, the mitochondrial reactive oxygen species (ROS) of HK-2 cells increased and the superoxide dismutase (SOD) activity was inhibited at the above three concentrations separately. Both ATP content and mitochondrial membrane potential decreased significantly at 100 µM concentration. The levels of procaspase-3 and Bcl-2 had fallen in a concentration-dependent manner and Bax was significantly increased at 60, 80 and 100 µM concentration compared with no CdCl2 treatment respectively, which activated the mitochondrial apoptosis pathway. N-acetyl-cysteine (NAC) could partially resist CdCl2-induced cell apoptosis, while myxothiazol (Myx) promoted the process. Mitochondria relative alterations manifested as inhibition of complex III and V. In addition, both the quantity of mitochondrial coenzyme Q-binding protein CoQ10 homolog B (CoQ10B) and cytochrome c (Cyt c) had decreased significantly. Taken together, CdCl2 induced HK-2 apoptosis due to the mitochondrial respiratory chain dysfunction by reducing the CoQ10B level, offering a novel evaluating indicator for the environmental toxicity of CdCl2.

CpG site-specific methylation as epi-biomarkers for the prediction of health risk in PAHs-exposed populations.

Environmental insults can lead to alteration in DNA methylation of specific genes. To address the role of altered DNA methylation in prediction of polycyclic aromatic hydrocarbons (PAHs) exposure-induced genetic damage, we recruited two populations, including diesel engine exhausts (low-level) and coke oven emissions (high-level) exposed subjects. The positive correlation was observed between the internal exposure marker (1-hydroxypyrene) and the extents of DNA damage (P < 0.05). The methylation of representative genes, including TRIM36, RASSF1a, and MGMT in peripheral blood lymphocytes was quantitatively examined by bisulfite-pyrosequencing assay. The DNA methylation of these three genes in response to PAHs exposure were changed in a CpG-site-specific manner. The identified hot CpG site-specific methylation of three genes exhibited higher predictive power for DNA damage than the respective single genes in both populations. Furthermore, the dose-response relationship analysis revealed a nonlinear U-shape curve of TRIM36 or RASSF1a methylation in combined population, which led to determination of the threshold of health risk. Furthermore, we established a prediction model for genetic damage based on the unidirectional-alteration MGMT methylation levels. In conclusion, this study provides new insight into the application of multiple epi-biomarkers for health risk assessment upon PAHs exposure.

Cadmium induces renal inflammation by activating the NLRP3 inflammasome through ROS/MAPK/NF-κB pathway in vitro and in vivo.

Cadmium (Cd) has been reported to induce kidney damage by triggering oxidative stress and inflammation. The NLR family Pyrin Domain Containing 3 (NLRP3) inflammasome has been implicated a role in the pathogenesis of inflammation. However, the connection between Cd and NLRP3 inflammasome in the development of renal inflammation remains unknown. In this study, in vitro experiments based on the telomerase-immortalized human renal proximal-tubule epithelial cell line (RPTEC/TERT1) were carried out. Results revealed that CdCl2 (2-8 µM) increased ROS production and activated NLRP3, thereby enhancing secretion of IL-1ß and IL-18 (P < 0.05). Knock-down of NLRP3 rescued the RPTEC/TERT1 cells from Cd-induced inflammatory damage. Cd activated the MAPK/NF-κB signaling pathway in RPTEC/TERT1 cells (P < 0.05). In addition, treatment with N-acetylcysteine (NAC) improved inflammation and blocked the upregulation of the MAPK/NF-κB signaling pathway. Pre-treatment with MAPK and NF-κB inhibitors also suppressed NLRP3 inflammasome activation (P < 0.05). Moreover, CdCl2 (25-00 mg/L) stimulated the MAPK/NF-κB signaling pathway, activated the NLRP3 inflammasome, and increased inflammatory response (P < 0.05) leading to renal injury in rats. Exposure to cadmium elevated serum levels of NLRP3 and IL-1ß in populations (P < 0.05). Further analysis found that serum NLRP3 and IL-1ß levels were positively correlated with urine cadmium (UCd) and urine N-acetyl-ß-D-glucosaminidase (UNAG). Overall, Cd induced renal inflammation through the ROS/MAPK/NF-κB signaling pathway by activating the NLRP3 inflammasome. Our research thus provides new insights into the molecular mechanism that NLRP3 contributes to Cd-induced kidney damage.

Association between H3K36me3 modification and methylation of LINE-1 and MGMT in peripheral blood lymphocytes of PAH-exposed workers.

To explore the epigenetic alterations in response to DNA damage following polycyclic aromatic hydrocarbons (PAHs) exposure and the crosstalk between different epigenetic regulations, we examined trimethylated Lys 36 of histone H3 (H3K36me3) and methylation of 'long interspersed element-1 (LINE-1)' and 'O 6-methylguanine-DNA methyltransferase (MGMT)' in peripheral blood lymphocytes (PBLCs) of 173 coke oven workers (PAH-exposed group) and 94 non-exposed workers (control group). The PAH-exposed group showed higher internal PAH exposure level, enhanced DNA damage and increased MGMT expression (all P < 0.001). Notably, the methylation of LINE-1 and MGMT decreased by 3.9 and 40.8%, respectively, while H3K36me3 level was 1.7 times higher in PBLCs of PAH-exposed group compared to control group (all P < 0.001). These three epigenetic marks were significantly associated with DNA damage degree (all P < 0.001) and PAH exposure level in a dose-response manner (all P < 0.001). LINE-1 hypomethylation is correlated with enhanced H3K36me3 modification (ß = -0.198, P = 0.002), indicating a synergistic effect between histone modification and DNA methylation at the whole genome level. In addition, MGMT expression was positively correlated with H3K36me3 modification (r = 0.253, P < 0.001), but not negatively correlated with MGMT methylation (r = 0.202, P < 0.05). The in vitro study using human bronchial epithelial cells treated with the organic extract of coke oven emissions confirmed that H3K36me3 is important for MGMT expression following PAH exposure. In summary, our study indicates that histone modification and DNA methylation might have synergistic effects on DNA damage induced by PAH exposure at the whole genome level and H3K36me3 is more essential for MGMT expression during the course.

Influence of benzene exposure, fat content, and their interactions on erythroid-related hematologic parameters in petrochemical workers: a cross-sectional study.

BACKGROUND: Ubiquitously distributed benzene is a known hematotoxin. Increasing evidence has suggested that erythroid-related hematologic parameters may be sensitive to benzene exposure. Fat content, which is also closely associated with erythroid-related hematologic parameters, may affect the distribution and/or metabolism of benzene, and eventually benzene-induced toxicity. METHODS: To explore the influence of benzene exposure, fat content, and their interactions on erythroid-related hematologic parameters, we recruited 1669 petrochemical workers and measured their urinary S-phenylmercapturic acid (SPMA) concentration and erythroid-related hematological parameters. Indices for fat content included body fat percentage (BF%), plasma total cholesterol (TC) and triglycerides (TG), and occurrence of fatty liver. RESULTS: The dose-response curve revealed U-shaped nonlinear relationships of SPMA with hematocrit (HCT) and mean corpuscular hemoglobin concentration (MCHC) (P-overall < 0.001, and P-nonlinear < 0.015), as well as positive linear associations and r-shaped nonlinear relationships of continuous fat content indices with erythroid-related hematological parameters (P-overall ≤0.005). We also observed modification effects of fat content on the associations between benzene exposure and erythroid-related hematological parameters, with workers of lower or higher BF% and TG more sensitive to benzene-induced elevation of MCHC (Pinteraction = 0.021) and benzene-induced decrease of HCT (Pinteraction = 0.050), respectively. We also found that some erythroid-related hematologic parameters differed between subgroups of workers with different SPMA levels and fat content combination. CONCLUSIONS: Our study suggested that benzene exposure, fat content, and their interactions may affect erythroid-related hematological parameters in petrochemical workers in a complex manner that are worthy of further investigation.

FLT1 hypermethylation is involved in polycyclic aromatic hydrocarbons-induced cell transformation.

Coke oven emissions (COEs) are common particle pollutants in occupational environment and the major constituents of COEs are polycyclic aromatic hydrocarbons (PAHs). Previously, we identified aberrant methylation of the fms related tyrosine kinase 1 (FLT1) gene over the course of benzo(a)pyrene (BaP)-induced cell transformation via genome-wide methylation array. To quantify FLT1 methylation, we established a bisulfite pyrosequencing assay and examined the FLT1 hypermethylation in several human cancers. The results revealed that 70.0% (21/30 pairs) of lung cancers harbored hypermethylated FLT1 and concomitant suppression of gene expression compared to the adjacent tissues. This implies that FLT1 hypermethylation might play a role in malignant cell transformation. In addition, FLT1 hypermethylation and gene suppression appeared in primary human lymphocytes in a dose-response manner following COEs treatment. To explore whether FLT1 methylation is correlated with COEs exposure and DNA damage, we recruited 144 male subjects who had been exposed to high levels of COEs and 84 male control subjects. Notably, the FLT1 methylation in peripheral blood lymphocytes (PBLCs) of the COEs-exposed group (19.8 ±â€¯3.2%) was enhanced by 17.9% compared to that of the control group (16.8 ±â€¯2.8%) (P < 0.001). The FLT1 methylation status was positively correlated with urinary 1-hydroxypyrene (1-OHP) levels, an internal exposure marker of PAHs (ß = 0.029, 95% CI = 0.010-0.048, P = 0.003) and positively correlated with DNA damage (ßOTM = 0.024, 95% CI = 0.007-0.040, P = 0.005; ßTail DNA = 0.035, 95% CI = 0.0017-0.054, P < 0.001) indicated by comet assay. Taken together, these findings indicate that FLT1 might be a tumor suppressor, and its hypermethylation might contribute to PAHs-induced carcinogenicity.

Strain differences between CD-1 and C57BL/6 mice in expression of metabolic enzymes and DNA methylation modifications of the primary hepatocytes.

Primary mouse hepatocyte cultures are widely used in toxicological and pharmacological studies. However, the strain differences in alterations of metabolic enzymes and the regulation of gene expression in response to different stimuli remains unclear. To address this issue, we examined the expression of metabolic enzymes and the regulatory role of DNA methylation in the primary hepatocytes of two mouse strains, CD-1 and C57BL/6. Primary culture of mouse hepatocytes was established using collagen sandwich configuration. Analysis of gene expression of 24 phase I, 18 phase II, and 6 phase III metabolic enzymes on 4 consecutive days after cell seeding revealed that the basal levels of most enzymes in primary cultured hepatocytes differed greatly between the two mouse strains. However, the dynamic changes in most genes were identical between the two strains. In addition, treatment with 3-methylcholanthrene, phenobarbital, and rifampin led to the induction of cytochrome P-450 (cyp) 1a1 and cyp1a2, cyp2b10, cyp3a11. However, induction varied in degree between the two types of primary hepatocytes. The dynamic changes in global DNA methylation and the expression of DNA methylation regulatory factors of the two mouse strains were similar. Of the genes down-regulated over the culture period, hypermethylation of cyp2e1 gene appeared in both mouse strains and led to a suppression of gene expression. Taken together, these results demonstrate that the expression of metabolic enzymes and the response to agonists in primary hepatocytes differ between CD-1 and C57BL/6 mouse strains. Epigenetic regulation might be involved in the suppression of cyp 450s' expression.

Benzene-induced mouse hematotoxicity is regulated by a protein phosphatase 2A complex that stimulates transcription of cytochrome P4502E1.

Chronic benzene exposure is associated with hematotoxicity and the development of aplastic anemia and leukemia. However, the signaling pathways underlying benzene-induced hematotoxicity remain to be defined. Here, we investigated the role of protein phosphatase 2A (PP2A) in the regulation of benzene-induced hematotoxicity in a murine model. Male mice with a hepatocyte-specific homozygous deletion of the Ppp2r1a gene (encoding PP2A Aα subunit) (HO) and matched wildtype (WT) mice were exposed to benzene via inhalation at doses of 1, 10, and 100 ppm for 28 days. Peripheral white blood cell counts and activation of bone marrow progenitors were attenuated in the HO mice, indicating that Ppp2r1a deletion protects against benzene-induced hematotoxicity. Moreover, elevation of urinary S-phenyl mercapturic acid, a benzene metabolite, was much greater in WT mice than in HO mice. Real-time exhalation analysis revealed more exhaled benzene but fewer benzene metabolites in HO mice than in WT mice, possibly because of the down-regulation of Cyp2e1, encoding cytochrome P4502E1, in hepatocytes of the HO mice. Loss-of-function screening disclosed that PP2A complexes containing the B56α subunit participate in regulating Cyp2e1 expression. Notably, PP2A-B56α suppression in HepG2 cells resulted in persistent ß-catenin phosphorylation at Ser33-Ser37-Thr41 in response to CYP2E1 agonists. In parallel, nuclear translocation of ß-catenin was inhibited, concomitant with a remarkable decrease of Cyp2e1 expression. These findings support the notion that a regulatory cascade comprising PP2A-B56α, ß-catenin, and Cyp2e1 is involved in benzene-induced hematotoxicity, providing critical insight into the role of PP2A in responses to the environmental chemicals.

The effects of Nrf2 knockout on regulation of benzene-induced mouse hematotoxicity.

Previous studies have demonstrated that oxidative stress is implicated in benzene-induced hematotoxicity. However, the low dose-response effects and the mechanism underlying perturbation of hematopoiesis remain to be defined. This study aims to address the role of Nrf2 pathway in mediating benzene-induced hematotoxicity. Nrf2+/+ (wildtype, Nrf2-WT) and Nrf2-/- (knockout, Nrf2-KO) mice were administrated with benzene at doses of 0.1, 1.0, 10.0, 100.0 mg/kg by oral gavage for a consecutive 4 weeks (6 times/week). As a result, benzene exposure caused a decline of WBC and lymphocyte counts in a dose-dependent manner at a dose range from 1.0 to 100.0 mg/kg, while low dose benzene induced hormesis effects. Interestingly, Nrf2 deficiency seemed to relieve the decline of peripheral blood cell counts upon benzene exposure, indicating the involvement of Nrf2 in regulation of benzene-induced hematotoxicity. The suppression of phase II enzyme expression in Nrf2-KO mice resulted in considerable reduction in detoxification indicated by the decrease of urinary S-phenylmercapturic acid (SPMA), a metabolite of benzene. Ex vivo assay revealed enhanced cytotoxicity and oxidative stress were induced by benzene in Nrf2-KO mice. Notably, the depletion of Nrf2 triggered the proliferation and differentiation of hematopoietic cells, but induced aberrant morphological changes in periphery erythrocytes and bone marrow cells, implicating the compensatory effects carried on at the expense of induction of dysfunctional blood cells. Our findings provide a new insight into a low dose-response towards benzene-induced hematotoxicity and uncover the critical role of Nrf2 pathway in mediating abnormal hematopoiesis in response to oxidative stress.