The unique biodegradation pathway of benzo[a]pyrene in moderately halophilic Pontibacillus chungwhensis HN14.

Benzo[a]pyrene (BaP), as the typical representative of polycyclic aromatic hydrocarbons (PAHs), is a serious hazard to human health and natural environments. Though the study of microbial degradation of PAHs has persisted for decades, the degradation pathway of BaP is still unclear. Previously, Pontibacillus chungwhensis HN14 was isolated from high salinity environment exhibiting a high BaP degradation ability. Here, based on the intermediates identified, BaP was found to be transformed to 4,5-epoxide-BaP, BaP-trans-4,5-dihydrodiol, 1,2-dihydroxy-phenanthrene, 2-carboxy-1-naphthol, and 4,5-dimethoxybenzo[a]pyrene by the strain HN14. Furthermore, functional genes involved in degradation of BaP were identified using genome and transcriptome data. Heterogeneous co-expression of monooxygenase CYP102(HN14) and epoxide hydrolase EH(HN14) suggested that CYP102(HN14) could transform BaP to 4,5-epoxide-BaP, which was further transformed to BaP-trans-4,5-dihydrodiol by EH(HN14). Moreover, gene cyp102(HN14) knockout was performed using CRISPR/Cas9 gene-editing system which confirmed that CYP102(HN14) play a key role in the initial conversion of BaP. Finally, a novel BaP degradation pathway was constructed in bacteria, which showed BaP could be converted into chrysene, phenanthrene, naphthalene pathways for the first time. These findings enhanced our understanding of microbial degradation process for BaP and suggested the potential of using P. chungwhensis HN14 for bioremediation in PAH-contaminated environments.

A unique circ_0067716/EIF4A3 double-negative feedback loop impacts malignant transformation of human bronchial epithelial cells induced by benzo(a)pyrene.

Benzo(a)pyrene as a pervasive environmental contaminant is characterized by its substantial genotoxicity, and epidemiological investigations have established a correlation between benzo(a)pyrene exposure and the susceptibility to human lung cancer. Notably, much research has focused on the link between epigenetic alterations and lung cancer induced by chemicals, although circRNAs are also emerging as relevant contributors to the carcinogenic process of benzo(a)pyrene. In this study, we identified circ_0067716 as being significantly upregulated in response to stress injury and downregulated during malignant transformation induced by benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE) in human bronchial epithelial cells. The observed differential expression of circ_0067716 in cells treated with BPDE for varying durations suggests a strong correlation between this circRNA and BPDE exposure. The tissue samples of lung cancer patients also suggest that a lower circ_0067716 expression is associated with BPDE-DNA adduct levels. Remarkably, we demonstrate that EIF4A3, located in the nucleus, interacts with the flanking sequences of circ_0067716 and inhibits its biogenesis. Conversely, circ_0067716 is capable of sequestering EIF4A3 in the cytoplasm, thereby preventing its translocation into the nucleus. EIF4A3 and circ_0067716 can form a double-negative feedback loop that could be affected by BPDE. During the initial phase of BPDE exposure, the expression of circ_0067716 was increased in response to stress injury, resulting in cell apoptosis through the involvement of miR-324-5p/DRAM1/BAX axis. Subsequently, as cellular adaptation progressed, long-term induction due to BPDE exposure led to an elevated EIF4A3 and a reduced circ_0067716 expression, which facilitated the proliferation of cells by stabilizing the PI3K/AKT pathway. Thus, our current study describes the effects of circ_0067716 on the genotoxicity and carcinogenesis induced by benzo(a)pyrene and puts forwards to the possible regulatory mechanism on the occurrence of smoking-related lung cancer, providing a unique insight based on epigenetics.

Transcriptomic and biochemical analysis of metabolic remodeling in Bacillus subtilis MSC4 under Benzo[a]pyrene stress.

Polyaromatic benzo[a]pyrene (B[a]P) is a toxic carcinogenic environmental pollutant, and the use of microorganisms to remediate B[a]P contamination is considered to be one of the most effective strategies. However, there is still a gap in studying the metabolic remodeling of microorganisms under B[a]P stress. In this study, our systematically investigated the effects of B[a]P on the metabolism of Bacillus subtilis MSC4 based on transcriptomic, molecular and biochemical analyses. The results showed that in response to B[a]P stress, MSC4 formed more biofilm matrix and endospores, the structure of the endospores also was changed, which led to a reduction in their resistance and made them more difficult to germinate. In addition to an increase in glycolysis activity, the activities of tricarboxylic acid cycle, pentose phosphate pathway and the electron transport chain were decreased. B[a]P stress forced MSC4 to strengthen arginine synthesis, urea cycle, and urea decomposition, meanwhile, synthesize more ribonucleotides. The activity of DNA replication, transcription activities and the expression of multiple ribosomal protein genes were reduced. Moreover, all of the reported enzymes involved in B[a]P degradation showed decreased transcript abundance, and the degradation of B[a]P caused significant up-regulation of the gene expression of the acid inducible enzyme OxdC and the synthesis of acetoin. In addition, the cytotoxicity of B[a]P to bacteria was directly displayed in four aspects: increased intracellular level of reactive oxygen species (ROS), elevated cell membrane permeability, up-regulation of the cell envelope stress-sensing two-component system LiaRS, and downregulation of siderophores biosynthesis. Finally, B[a]P also caused morphological changes in the cells, with some cells exhibiting significant deformation and concavity. These findings provide effective research directions for targeted improvement the cellular activity of B[a]P-degrading strains, and is beneficial for further application of microorganisms to remediate B[a]P -contaminated soils.

A commercial humic acid inhibits benzo(a)pyrene biodegradation by Paracoccus aminovorans HPD-2.

Benzo(a)pyrene (BaP) is posing serious threats to soil ecosystems and its bioremediation usually limited by environmental factors and microbial activity. Humic acid (HA), a ubiquitous heterogeneous organic matter, which could affect the fate of environmental pollutants. However, the impact of HA on bioremediation of organic contamination remains controversial. In the present study, the biodegradation of BaP by Paracoccus aminovorans HPD-2 with and without HA was explored. Approximately 87.4 % of BaP was biodegraded in the HPD-2 treatment after 5 days of incubation, whereas the addition of HA dramatically reduced BaP biodegradation to 56.0 %. The limited BaP biodegradation in the HA + HPD-2 treatment was probably due to the decrease of BaP bioavailability which induced by the adsorption of HA with unspecific interactions. The excitation-emission matrix (EEM) of fluorescence characteristics showed that strain HPD-2 was responsible for the presence of protein-like substances and the microbial original humic substances in the HPD-2 treatment. Addition of HA would result in the increase of soluble microbial humic-like material, which should ascribe to the biodegradation of BaP and probably utilization of HA. Furthermore, both the growth and survival of strain HPD-2 were inhibited in the HA + HPD-2 treatment, because of the limited available carbon source (i.e. BaP) at the presence of HA. The expression of gene1789 and gene2589 dramatically decreased in the HA + HPD-2 treatment, and this should be responsible for the decrease of BaP biodegradation as well. This study reveals the mechanism that HA affect the BaP biodegradation, and the decrease of biodegradation should ascribe to the interaction of HA and bacterial strain. Thus, the bioremediation strategies of PAHs need to consider the effects of organic matter in environment.

Mechanisms of benzene and benzo[a]pyrene biodegradation in the individually and mixed contaminated soils.

There is a lack of knowledge on the biodegradation mechanisms of benzene and benzo [a]pyrene (BaP), representative compounds of polycyclic aromatic hydrocarbons (PAHs), and benzene, toluene, ethylbenzene, and xylene (BTEX), under individually and mixed contaminated soils. Therefore, a set of microcosm experiments were conducted to explore the influence of benzene and BaP on biodegradation under individual and mixed contaminated condition, and their subsequent influence on native microbial consortium. The results revealed that the total mass loss of benzene was 56.0% under benzene and BaP mixed contamination, which was less than that of individual benzene contamination (78.3%). On the other hand, the mass loss of BaP was slightly boosted to 17.6% under the condition of benzene mixed contamination with BaP from that of individual BaP contamination (14.4%). The significant differences between the microbial and biocide treatments for both benzene and BaP removal demonstrated that microbial degradation played a crucial role in the mass loss for both contaminants. In addition, the microbial analyses revealed that the contamination of benzene played a major role in the fluctuations of microbial compositions under co-contaminated conditions. Rhodococcus, Nocardioides, Gailla, and norank_c_Gitt-GS-136 performed a major role in benzene biodegradation under individual and mixed contaminated conditions while Rhodococcus, Noviherbaspirillum, and Phenylobacterium were highly involved in BaP biodegradation. Moreover, binary benzene and BaP contamination highly reduced the Rhodococcus abundance, indicating the toxic influence of co-contamination on the functional key genus. Enzymatic activities revealed that catalase, lipase, and dehydrogenase activities proliferated while polyphenol oxidase was reduced with contamination compared to the control treatment. These results provided the fundamental information to facilitate the development of more efficient bioremediation strategies, which can be tailored to specific remediation of different contamination scenarios.

Differential effects of benzo[a]pyrene exposure on glutathione and purine metabolism in keratinocytes: Dose-dependent and UV co-exposure effects.

Polycyclic aromatic hydrocarbons with the key substance benzo[a]pyrene (B[a]P) are widespread pollutants in the environment and at working places. Nonetheless, the exact underlying mechanisms of toxicological effects caused by B[a]P especially in absence and presence of UV irradiation remain uncertain. This study examines variations in exposure conditions: low B[a]P (4 nM), low B[a]P + UV and high B[a]P (4 µM), selected based on pertinent cytotoxicity assessments. Following cell viability evaluations post-treatment with varied B[a]P concentrations and UV irradiation, the identified concentrations underwent detailed metabolomic analysis via gas chromatography-mass spectrometry. Subsequently, resulting changes in metabolic profiles across these distinct exposure groups are comprehensively compared. Chemometric analyses showed modest regulation of metabolites after low B[a]P exposure compared to control conditions. High B[a]P and low B[a]P + UV exposure significantly increased regulation of metabolic pathways, indicating that additional UV irradiation plus low B[a]P is as demanding for the cells as higher B[a]P treatment alone. Further analysis revealed exposure-dependent regulation of glutathione-important for oxidative defence-and purine metabolism-important for DNA base synthesis. Only after low B[a]P, oxidative defence appeared to be able to compensate for B[a]P-induced perturbations of the oxidative homeostasis. In contrast, purine metabolism already responded towards adversity at low B[a]P. The metabolomic results give an insight into the mechanisms leading to the toxic response and confirm the strong effects of co-exposure on oxidative defence and DNA repair in the model studied.

hsa_circ_0008500 regulates Benzo(a)pyrene-loaded gypsum-induced inflammation and apoptosis in human bronchial epithelial cells via activation of Ahr/C-myc pathways.

Polycyclic aromatic hydrocarbons (PAHs) are major organic pollutants attached to fine particulate matter in the atmosphere. They induce lung inflammation, asthma, and other lung diseases. Exploring the toxic mechanism of PAHs on lung epithelial cells may provide a theoretical basis for the prevention and treatment of respiratory diseases induced by PAHs. In our study, 16 human bronchial epithelial (16HBE) cells were exposed to different concentrations of gypsum dust, Benzo(a)pyrene (BaP), and BaP-loaded gypsum dust for 24 hours. Gypsum dust loaded with BaP significantly increased the cytotoxicity of 16HBE cells, enhanced the production of lactate dehydrogenase (LDH), interleukin-6 (IL-6) and interleukin-8 (IL-8), induced cell apoptosis, and upregulate the expression of hsa_circ_0008500 (circ_0008500). The mechanism was studied with a BaP-loaded gypsum dust concentration of 1.25 mg/mL. StemRegenin 1 (SR1) pretreat significantly reduced the release of LDH, IL-6, and IL-8 and decreased the protein levels of Ahr、XAP2, C-myc, and p53. Second-generation sequencing indicated that circ_0008500 was highly expressed after 16HBE induced by BaP-loaded gypsum dust. Functional experiments confirmed that circ_0008500 promoted the inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust by regulating the Ahr signaling pathway. Our study showed that fine particulate matter adsorption of BaP significantly increased the toxic effect of BaP on cells. By activating the Ahr/C-myc pathway, circ_0008500 promoted inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust.

Combination therapy of metformin and atorvastatin against benzopyrene-induced lung cancer via inflammatory signaling pathway.

The most prevalent cause of lung cancer is smoking tobacco, but exposure to second hand smoke, air pollution, and certain chemicals and substances at work can also raise the risk of disease. In this study, we scrutinized the chemoprotective effect of the metformin and atorvastatin combination against benzo[a]pyrene (BaP)-induced lung cancer in mice of Swiss albino. BaP (50 mg/kg) was used for induction of lung cancer and mice were treated with metformin, atorvastatin or their combination. Metformin + atorvastatin combination significantly (p< 0.001) improved the body weight, liver weight, suppressed the lung weight and tumor incidence and altered the levels of immunocompetent cells, polyamines, lung tumor markers, lung parameters and antioxidant parameters, respectively. Metformin + atorvastatin combination also suppressed cytokines levels, inflammatory parameters and caspase parameters. On the basis of the results, we can conclude that metformin + atorvastatin combination remarkably suppressed lung cancer via the inflammatory pathway.

The toxicity response of the electrochemical signal of the cell to the drug metabolized by the S9 system.

The electrochemical detection method of cytotoxicity using intracellular purines as biomarkers has shown great potential for in vitro drug toxicity evaluation. However, no electrochemical detection system based on an in vitro drug metabolism mechanism has been devised. In this paper, electrochemical voltammetry was used to investigate the effect of the S9 system on the electrochemical behavior of HepG2 cells, and benzo[a]pyrene, fluoranthene, and pyrene were employed to investigate the sensitivity of electrochemical signals of cells to the cytotoxicity of drugs metabolized by the S9 system. The results showed that, within 8 h of exposure to the S9 system, the electrochemical signal of HepG2 cells at 0.7 V did not alter noticeably. The levels of xanthine, guanine, hypoxanthine, and adenine in the cells were not significantly altered. Compared with the absence of S9 system metabolism, benzo[a]pyrene and fluoranthene processed by the S9 system decreased the electrochemical signal of the cells in a dose-dependent manner, while pyrene did not change it appreciably. HPLC also revealed that benzo[a]pyrene and fluoranthene metabolized by the S9 system decreased the intracellular purine levels, whereas pyrene had no effect on them before and after S9 system metabolism. The cytotoxicity results of the three drugs examined by electrochemical voltammetry and MTT assay showed a strong correlation and good agreement. The S9 system had no effect on the intracellular purine levels or the electrochemical signal of cells. When the drug was metabolized by the S9 system, variations in cytotoxicity could be precisely detected by electrochemical voltammetry.

A low dose of benzo(a)pyrene during prepuberty in male rats generated immediate oxidative stress in the testes and compromised steroidogenic enzymes/proteins.

The prepubertal period is crucial for sexual development and any alterations can interfere with the reproductive system in adulthood. The aim of this study was to evaluate how Benzo(a)pyrene (BaP) can affect the testes during the prepubertal period. Juvenile male Wistar rats were divided into a control (corn oil + DMSO) and a BaP-group (0.1 µg/kg/day), exposed to BaP for 31 days (gavage), and all parameters were evaluated on postnatal day (PND) 54. Leukocyte counts were decreased. Histological analyses of the testes revealed that height and seminiferous tubules diameters (STDs) were reduced, tubular dynamics were altered, and Leydig cell atrophy was evident in the BaP-group. The testosterone concentration was decreased while FSH levels increased within the BaP-exposed group. Steroidogenic enzymes in the testes were decreased, but steroidogenic acute regulatory protein was not altered. The expression of gstp1 and ckit enzymes was decreased. Reduced glutathione (GSH) and superoxide dismutase (SOD) were increased, whereas malondialdehyde (MDA) was decreased in the testes. In conclusion, BaP or its metabolites causes low systemic toxicity; however, it adversely influences testicular function by disrupting the hormonal axis, unbalancing testicular antioxidative, and blocking the action of the steroidogenic mechanisms.

Interference mechanism of benzo[a]pyrene exposure on the taste substance metabolisms in Ruditapes philippinarum.

Aquatic animals are popular for their unique umami and high-quality protein. However, under the realistic background of increasing marine pollution, whether it affects the aquatic animal tastes, and what the interference mechanism is still remains unknown. Benzo[a]pyrene (B[a]P) is a typical Polycyclic aromatic hydrocarbons (PAHs) with high toxicity. In this study, we investigated the effects of B[a]P (0, 0.8, 4 and 20 µg/L) on the content and taste evaluation of Ruditapes philippinarum taste substances, and clarified the interference mechanism of B[a]P on taste substance metabolisms with transcriptome analysis. The results demonstrated that B[a]P significantly altered the contents and taste activity values (TAVs) of free amino acids (FAAs), 5'-nucleotides, organic acids, flavor peptides, organic bases, sugars and inorganic ions, as well as the gene expressions within their synthesis and decomposition, indicating that B[a]P affected these taste substance contents by interfering with their metabolisms, thereby changing the clam tastes (decreases of umami and sweetness, and increase of bitter taste). This study provided scientific basis for quality assurance of bivalve cultivation and control of marine pollution.

Gene architecture is a determinant of the transcriptional response to bulky DNA damages.

Bulky DNA damages block transcription and compromise genome integrity and function. The cellular response to these damages includes global transcription shutdown. Still, active transcription is necessary for transcription-coupled repair and for induction of damage-response genes. To uncover common features of a general bulky DNA damage response, and to identify response-related transcripts that are expressed despite damage, we performed a systematic RNA-seq study comparing the transcriptional response to three independent damage-inducing agents: UV, the chemotherapy cisplatin, and benzo[a]pyrene, a component of cigarette smoke. Reduction in gene expression after damage was associated with higher damage rates, longer gene length, and low GC content. We identified genes with relatively higher expression after all three damage treatments, including NR4A2, a potential novel damage-response transcription factor. Up-regulated genes exhibit higher exon content that is associated with preferential repair, which could enable rapid damage removal and transcription restoration. The attenuated response to BPDE highlights that not all bulky damages elicit the same response. These findings frame gene architecture as a major determinant of the transcriptional response that is hardwired into the human genome.

Enhancing resistance and cell survival in Acipenser ruthenus liver, gill, and kidney cells: The potential of heat shock protein inducers against PAH-benzo[a]pyrene stress.

The Caspian Sea has faced many environmental challenges, such as oil pollution. Heat shock proteins (HSPs) play a critical role in stress conditions and physiological changes caused by disease or injury. By evaluating the effects of various HSP inducers (HSPi), including Pro-Tex® (NOP: 800 mM), amygdalin (AMG: 80 mM), and a novel synthetic compound derived from pirano piranazole (SZ: 80 µm) on isolated cells from Sterlet Sturgeon (Acipenser ruthenus) treated with 75% IC50 PAH-benzo[a]pyrene (BaP; B75). This study examines whether there is a correlation between exposure to the BaP pollutant and HSPs in fish. In vitro, after culturing cells from the liver, kidney, and gills, they were treated with HSPi compounds in the presence and absence of BaP. Western blotting was used to assess HSP27, HSP70, and HSP90 expression patterns. A variety of enzyme activities were measured before (without treatment) and after treatment with HSPis and HSPi + B75, including cytochrome P450 (CYP450) activity, specific enzyme activity for acetylcholinesterase (AChE), antioxidant capacity, liver indicator enzymes, cortisol levels, and immunity parameters. When compared to the control group, cells treated with B75 showed the lowest AChE enzyme activity (p < 0.0001). CYP450 activity was highest in group B75, while HSPi caused the opposite effect (p < 0.0001). HSPi + B75 increased HSP levels and antioxidant parameters while decreasing cortisol and liver indicator enzymes (p < 0.0001). HSPi may be a powerful and reliable method for enhancing the resistance of A. ruthenus to BaP stresses before exposure. Treating cells with HSP-inducing compounds, such as NOP, AMG, and SZ, can assist them in managing stress and increase HSP (27, 70, and 90) protein expression. Furthermore, the study findings suggest that HSPis can also mitigate the adverse effects of stress, ultimately increasing cell survival and resistance.

Bacterial response to the combined pollution of benzo[a]pyrene and decabromodiphenyl ether in soil under flooding anaerobic condition.

This study investigated the interaction between the co-pollutants of Benzo[a]pyrene (BaP) and decabromodiphenyl ether (BDE-209) and the bacterial community in soil under flooding anaerobic condition. Three levels of combined pollution (at nominal concentrations of 1, 5, and 25 mg/kg, respectively, for each pollutant), their corresponding sterilized controls, and a blank control (CK) were set up. During the incubation time of 270 days, BaP attenuated more easily than BDE-209. The second-order rate constant of BaP attenuation was negatively correlated with the Ln value of initial BaP concentration. Maximal difference in bacterial community occurred between the CK soil and the highly polluted soil. Desulfomonilaceae, Parcubacteria and Rhodanobacter were probably involved in BaP and BDE-209 degradation, while Nitrosomonadaceae, Phenylobacterium and Mitochondria were significantly suppressed by BaP and BDE-209 or their degrading products. Genes narI, bcrC, fadJ, had, dmpC, narG and CfrA were involved in the degradation of BaP and BDE-209. Impacts of BaP and BDE-209 on metabolisms of carbon, nitrogen and sulfur were not significant. The results provide guidance for the management and remediation of the contaminated soil.

Effects of short and long-term thermal exposure on microbial compositions in soils contaminated with mixed benzene and benzo[a]pyrene: A short communication.

Polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylene (BTEX) are the most persistent and toxic organic contaminants often found co-contaminated in anthropogenic and petrochemical industrial sites. Therefore, an experiment was performed for the safe biodegradation of benzene and benzo[a]pyrene (BaP) through thermally-enhanced biodegradation, and to explore the influence of elevated thermal treatments on microbial diversity and composition. The results revealed that elevated thermal treatments (15 to 45 °C) significantly enhanced the diversity of both bacteria and fungi. The composition analysis revealed that short-term and long-term elevated temperature conditions can directly enhance the specificity of microorganisms that play a crucial role in the biodegradation of benzene and BaP co-contaminated soil. Moreover, the indirect role of elevated temperature conditions on microbial compositions was through the fluctuations of soil properties, especially soil pH, moisture, TOC, potassium, phosphorous, total Fe, Fe(II), and Fe(III). In addition, the correlation analyses revealed that thermal exposure enhances the synergistic association (fungal-fungal, fungal-bacterial, bacterial-bacterial) of microbes to degrade the toxic contaminants and to cope with harsh environmental conditions. These results concluded that the biodegradation of benzene and BaP co-contamination was efficiently enhanced under the thermally-enhanced biodegradation approach and the elevation of temperature can affect the microbial compositions directly via microbial specificity or indirectly by influencing the soil properties.

Study on epigenotoxicity, sex hormone synthesis, and DNA damage of benzo[a]pyrene in the testis of male Ruditapes philippinarum.

Research on the mechanisms of reproductive toxicity caused by persistent organic pollutants (POPs) in marine animals has received significant attention. One group of typical POPs, called polycyclic aromatic hydrocarbons (PAHs), has been found to cause various reproductive toxicities in aquatic organisms, including epigenotoxicity, reproductive endocrine disruption, DNA damage effects and other reproductive toxicity, thereby affecting gonadal development. Interestingly, male aquatic animals are more susceptible to the disturbance and toxicity of environmental pollutants. However, current studies primarily focus on vertebrates, leaving a large gap in our understanding of the reproductive toxicity and mechanisms of PAHs interference in marine invertebrates. In this study, male Ruditapes philippinarum was used as an experimental subject to investigate reproduction-related indexes in clams under the stress of benzo[a]pyrene (B[a]P) at different concentrations (0, 0.8, 4 and 20 µg/L) during the proliferative, growth, maturity, and spawning period. We analyzed the molecular mechanisms of reproductive toxicity caused by PAHs in marine bivalves, specifically epigenotoxicity, reproductive endocrine disruption, and gonadal damage-apoptotic effect. The results suggest that DNA methylation plays a crucial role in mediating B[a]P-induced reproductive toxicity in male R. philippinarum. B[a]P may affect sex hormone levels, impede spermatogenesis and testis development in clams, by inhibiting the steroid hormone synthesis pathway and downregulating genes critical for cell proliferation, testis development, and spermatid expulsion. Moreover, the spermatids of male R. philippinarum were severely impaired under the B[a]P stress, leading to reduced reproductive performance in the clams. These findings contribute to a better understanding of the reproductive toxicity response of male marine invertebrates to POPs stress.

Mechanisms and targeted reversion/prevention of hepatic fibrosis caused by the non-hereditary toxicity of benzo(a)pyrene.

The effect of long term exposure to low concentrations of environmental pollutants on hepatic disorders is a major public health concern worldwide. Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants. In recent years, an increasing number of studies have focused on the deleterious effects of low concentrations of PAHs in the initiation or exacerbation of the progression of chronic liver disease. However, the underlying molecular mechanisms and effective intervention methods remain unclear. Here, we found that in hepatocytes, a low concentration of benzo(a)pyrene (B[a]P, an indicator of PAHs) chronic exposure continuously activated 14-3-3η via an epigenetic accumulation of DNA demethylation. As a "switch like" factor, 14-3-3η activated its downstream PI3K/Akt signal, which in turn promoted vascular endothelial growth factor (VEGF) production and secretion. As the characteristic fibrogenic paracrine factor regulated by B[a]P/14-3-3η, VEGF significantly induced the neovascularization and activation of hepatic stellate cells, leading to the development of hepatic fibrosis. Importantly, targeted 14-3-3η by using its specific inhibitor invented by our lab could prevent B[a]P-induced hepatic fibrosis, and could even reverse existent hepatic fibrosis caused by B[a]P. The present study not only revealed novel mechanisms, but also proposed an innovative approach for the targeted reversion/prevention of the harmful effects of exposure to PAHs on chronic liver disease.

Toxic effects of polystyrene microbeads and benzo[α]pyrene on bioaccumulation, antioxidant response, and cell damage in goldfish Carassius auratus.

Microplastics (MP) are harmful, causing stress in aquatic species and acting as carriers of hydrophobicity. In aquatic environments, benzo[α]pyrene (BaP) is an endocrine-disrupting chemical that accumulates in the body and causes toxic reactions in living organisms. We investigated the effects of single and combined microbead (MB) and BaP environments on goldfish antioxidant response and apoptosis. For 120 h, goldfish were exposed to single (MB10, MB100, and BaP5) and combined (MB10+BaP5 and MB100+BaP5) environments of 10 and 100 beads/L of 0.2 µm polystyrene MB and 5 µg/L BaP. We measured MB and BaP bioaccumulation as well as plasma parameters including ALT, AST, and glucose. The level of oxidative stress was determined by evaluating lipid peroxidation (LPO) and total antioxidant capacity (TAC) in plasma, as well as antioxidant-related genes for superoxide dismutase and catalase (SOD and CAT) and caspase-3 (Casp3) mRNA expression in liver tissue. The TUNEL assay was used to examine SOD in situ hybridization and apoptosis in goldfish livers. Except for the control group, plasma LPO levels increased at the end of the exposure period in all experimental groups. TAC increased up to 24 h of exposure and then maintained a similar level until the trial ended. SOD, CAT, and Casp3 mRNA expression increased substantially up to 120 h as the exposure concentration and time increased. The TUNEL assay revealed more signals and apoptotic signals in the combined exposure environments as a consequence of SOD in situ hybridization than in single exposure environments. These results suggest that combined exposure to toxic substances causes oxidative stress in organisms, which leads to apoptosis.

Ameliorative potential of synbiotic combination of Lactobacillus sp. and polyphenols against Benzo[a]pyrene-induced toxicity in Caco-2 cell line.

Exposure to benzo[a]pyrene (B[a]P), a major global food safety concern, is often associated with increasing incidence of colorectal cancers. This in-vitro study was focused on the identification of potential B[a]P-adsorbing Lactobacillus strains and evaluation of the ameliorative effect of synbiotic combination of selected Lactobacillus sp. and polyphenols (quercetin or resveratrol) against B[a]P-induced intestinal toxicity in Caco-2 cells. Preliminary studies lead to the selection of Lactiplantibacillus plantarum MTCC 25433 strain that showed 86% of B[a]P adsorption in 2 h as compared to L. rhamnosus GG that showed 74% of B[a]P adsorption. B[a]P adsorption by MTCC 25433 was reduced to 9%, 16% and 20% upon pre-treatment with SDS, NaIO4 and mutanolysin, attributing the involvement of cell wall proteins and polysaccharides in the adsorption. Additionally, peptidoglycan of both strains adsorbed >50% of B[a]P. In-vitro assays revealed that the selected LAB mitigated the B[a]P-induced epithelial cell damage. Among the polyphenols, quercetin, resveratrol and curcumin, varied in their potency to mitigate B[a]P-induced oxidative stress, with curcumin being least effective. Combinations of selected Lactobacillus sp. and polyphenols were more potent in averting B[a]P-induced toxicity via increase in GSH (17-30 %), SOD (50-88 %), catalase (19-45 %), and reduction in IL-8 secretion (14-28 %) and barrier dysfunction. Principal component analysis affirmed the superior potency of combination of L. plantarum MTCC 25433 and quercetin in averting B[a]P-induced toxicity. Overall, this study highlighted a novel promising strategy of synbiotic combination of Lactobacillus sp. and polyphenols (quercetin or resveratrol) in alleviating the B[a]P-induced toxicity in intestinal epithelial cells.

Functional polymorphisms in Benzo(a)Pyrene-induced toxicity pathways associated with the risk on laryngeal squamous cell carcinoma.

Benzo(a)Pyrene (BaP) is a well-known environmental carcinogen that poses a significant risk to human health. The pivotal genes and toxicity pathways have been identified as key events to construct the mode of action (MOA) of BaP. In this study, we focused on evaluating the association between genetic variants in BaP-disturbed toxicity pathways and the susceptibility of laryngeal squamous cell carcinoma (LSCC), based on the data of our previous genome-wide association analysis (GWAS). In addition, we investigated the biological roles of these significant polymorphisms by integrating bioinformatic annotation and experimental validation. Our findings revealed that 15 functional polymorphisms in AHR signaling, p53 signaling, NRF2 signaling, TGF-ß signaling, STAT3 signaling, and IL-8 signaling pathways were significantly associated with susceptibility to LSCC. Our study provides a novel approach for identifying novel risk genetic loci utilizing GWAS data, and suggests potential targets for early detection of LSCC in the future.