Identification of hepatotoxicity and renal dysfunction of pyrene in adult male rats

Exposure to polycyclic aromatic hydrocarbons and risk of abnormal liver function: The mediating role of C-reactive protein

Polycyclic aromatic hydrocarbons (PAHs) exposure has been suggested to be linked to abnormal liver function (ALF). However, the conclusions are inconsistent, and the underlying mechanism is still unclear. In this study, a cross-sectional design including 4935 adults from the National Health and Nutrition Examination Survey (NHANES) between 2003 and 2010 was conducted to quantify the PAHs-ALF associations, and to investigate the possible mediation role of systemic inflammation. Capillary gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was utilized to detect nine urinary levels of PAH metabolites (OH-PAHs). Plasma levels of systemic inflammation biomarker, C-reactive protein (CRP), were measured by enhanced turbidimetry. ALF was diagnosed on the basis of any abnormities in albumin (ALB), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), and alanine aminotransferase (ALT). Logistic regression model and the least absolute shrinkage and selection operator (LASSO) regression models indicated positive associations between urinary 1-hydroxypyrene (1-OH-PYR), 2-hydroxyphenanthrene (2-OH-PHE), and ALF risk. Significant synergistic effect of 1-OH-PYR and 2-OH-PHE on ALF was observed via additive interaction analysis. The weighted quantile sum (WQS) analysis and the quantile-based g computation (qgcomp) were employed to investigate the mixed effect of PAHs but no significant results were found. However, these two analyses consistently showed that 2-OH-PHE and 1-OH-PYR had top dominant weights in the positive association with ALF. Furthermore, mediation analysis indicated that plasma CRP mediated 13.4 % of the association between 1-OH-PYR and ALF risk. These results enhanced our comprehension of the health effects of PAHs exposure on liver function as well as the underlying mechanism.

Impact of Benzo(a)pyrene and Pyrene Exposure on Activating Autophagy and Correlation with Endoplasmic Reticulum Stress in Human Astrocytes

Benzo(a)pyrene (B(a)P) and pyrene, the most prominent subtypes of polycyclic aromatic hydrocarbons (PAHs), contaminate environments as organic pollutants. They adversely affect body systems, including degeneration of the central nervous system. This study investigated the in vitro toxic effects of B(a)P and pyrene on proliferation, endoplasmic reticulum (ER) stress induction, and autophagy in human astrocytes using U-87 MG human astrocytoma cells as a model. Both B(a)P and pyrene were toxic to U-87 MG cells in a concentration-dependent manner. Astrocytic proliferation was interfered with, enhancing S-phase cell cycle arrest. B(a)P promoted the presence of autophagic vesicles and the expression of autophagic markers LC3, beclin-1, and p62, suggesting activated autophagy. B(a)P enhanced the expression of ER stress markers BiP, PERK, and IRE1. ER stress appeared to be correlated with autophagy induction, as demonstrated by experiments using chloroquine, an autophagy inhibitor. Pyrene enhanced the expression of autophagic markers and ER stress primarily via PERK activation, although autophagic vesicles were not observed. The study demonstrates that B(a)P enhances ER stress-mediated autophagy more evidently than pyrene and affected toxicity to astrocytes. These results provide a basis for understanding the toxic effects of the main PAH substances affecting astrocytes.

Ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) associated with pro-thrombotic biomarkers among young healthy adults: A 16 times repeated measurements panel study

Studies have shown that the cardio/cerebrovascular toxicity of ambient PM2.5 is related to its bound polycyclic aromatic hydrocarbons (PAHs). Currently, only a few studies have reported the relationship between PM2.5-bound PAHs and promoted blood coagulation and thrombosis, but there isn't a consistent conclusion. Therefore, we conducted a prospective panel study to investigate the association. Thirty-three young healthy adults participated in sixteen repeated visits from 2014 to 2018 in Tianjin, China. During each visit, three pro-thrombotic biomarkers: ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin motif 13), D-dimer and Myeloperoxidase (MPO) were measured. Before each visit, ambient PM2.5 samples were daily collected for one week. Sixteen PAHs were determined using Gas Chromatography-Mass Spectrometer, and the positive matrix factorization (PMF) model was applied to identify the sources. Linear mixed-effects models were fitted to investigate the associations between PM2.5-bound PAHs exposure and the biomarkers. Thirteen time-metrics were defined to identify significant time points of PM2.5-bound PAHs' effects. We observed that the increase of PM2.5-bound PAHs exposure was significantly associated with reduced ADAMTS13, elevated D-dimer and MPO. At lag0, each 5.7 ng/m3 increase in Benzo[j]fluoranthene and per 3.4 ng/m3 increase Dibenz[a,h]anthracene could make a maximum change of -19.08 % in ADAMTS13 and 132.60 % in D-dimer. Additionally, per 16.43 ng/m3 increase in Chrysene could lead to a maximum elevation of 32.14 % in MPO at lag4. The PM2.5-bound PAHs often triggered more significant changes at lag 3,4 and 6. The ambient PM2.5-bound PAHs originated from six sources: coal combustion (43.10 %), biomass combustion (20.77 %), diesel emission (14.78 %), gasoline emission (10.95 %), industrial emission (7.58 %), and cooking emission (2.83 %). The greatest contributors to alterations in ADAMTS13, D-dimer and MPO are industrial emission (-48.43 %), biomass combustion (470.32 %) and diesel emission (13.14 %) at lag4. Our findings indicated that short-term exposure to ambient PM2.5-bound PAHs can induce alterations of pro-thrombotic biomarkers among healthy adults.

Associations between inhalation of typical volatile and semi-volatile organic compounds in e-waste dismantling workers with liver function damage

Studies in cell culture and animal models suggest hepatotoxicity of some volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), however, their effects in human populations under real exposure conditions have never been clarified. In this cross-sectional study, 224 participants, 38 e-waste dismantling workers and 186 subjects residing near to the dismantling sites in southern China, were evaluated for personal inhalational exposure to 72 VOCs and 91 SVOCs according to site-specific atmospheric chemical concentrations and personal exposure time. Additionally, their serum samples were subjected to liver function tests (LFTs), including total protein (TP), albumin (ALB), globulin (GLB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and bilirubin. Linear regression analysis of the VOC/SVOC levels against the LFTs results indicated that VOC exposure was negatively associated with the TP, ALB, GLB levels (indicating liver-specific protein synthesis functions), while positively associated with AST, ALT, GGT activities (marking liver damage). Somehow, SVOC exposure appeared to be positively associated with not only AST and ALT but also TP and ALB. These findings were supported by the quantile g-computation analysis and confirmed in the Bayesian kernel machine regression model. This study indicates that simultaneous inhalation of VOCs and SVOCs may impair human liver functions.

Kernel extreme learning with harmonized bat algorithm for prediction of pyrene toxicity in rats

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants and manufactured substances conferring toxicity to human health. The present study investigated whether pyrene, a type of PAH, harms rats. Our research provides an effective feature selection strategy for the animal dataset from Wenzhou Medical University's Experimental Animal Center to thoroughly examine the impacts of PAH toxicity on rat features. Initially, we devised a high-performance optimization method (SCBA) and added the Sobol sequence, vertical crossover and horizontal crossover mechanisms to the bat algorithm (BA). The SCBA-KELM model, which combines SCBA with the kernel extreme learning machine model (KELM), has excellent accuracy and high stability for selecting features. Benchmark function tests are then used in this research to verify the overall optimization performance of SCBA. In this paper, the feature selection performance of SCBA-KELM is verified using various comparative experiments. According to the results, the features of the genes PXR, CAR, CYP2B1/2 and CYP1A1/2 have the most impact on rats. The SCBA-KELM model's classification performance for the gene dataset was 100%, and the model's precision value for the public dataset was around 96%, as determined by the classification index. In conclusion, the model utilized in this research is anticipated to be a reliable and valuable approach for toxicological classification and assessment.

Single and Joint Associations of Polycyclic Aromatic Hydrocarbon Exposure with Liver Function during Early Pregnancy

The individual and combined associations of polycyclic aromatic hydrocarbons (PAHs) metabolites on liver function during pregnancy are still lacking. We aimed to explore the connection between urinary PAH metabolites and liver function in early pregnant women in southwest China based on the Zunyi birth cohort. Ten urinary PAH metabolites and five liver function parameters during early pregnancy were measured. The associations of single PAHs with parameters of liver function were assessed using multiple linear regression. A Bayesian kernel machine regression (BKMR) model was used to evaluate the joint associations of the PAH mixture with outcomes. We found that each 1% increment of urinary 2-hydroxyphenanthrene (2-OH-PHE) was associated with 3.36% (95% CI: 0.40%, 6.40%) higher alanine aminotransferase (ALT) and 2.22% (95% CI: 0.80%, 3.67%) higher aspartate aminotransferase (AST). Each 1% increment in 1-hydroxy-phenanthrene (1-OH-PHE) was significantly associated with 7.04% (95% CI: 1.61%, 12.75%) increased total bile acid (TBA). Additionally, there was a significant positive linear trend between 2-OH-PHE and AST and 1-OH-PHE and TBA. BKMR also showed a significant positive association of PAH mixture with AST. Our results indicate that PAH metabolites were associated with increased parameters of liver function among early pregnant women. Early pregnant women should pay more attention to the adverse relationships between PAHs and liver function parameters to prevent environment-related adverse perinatal outcomes.

Firefighters and the liver: Exposure to PFAS and PAHs in relation to liver function and serum lipids (CELSPAC-FIREexpo study)

INTRODUCTION

Firefighting is one of the most hazardous occupations due to exposure to per- and polyfluoroalkyl substances (PFAS) and polycyclic aromatic hydrocarbons (PAHs). Such exposure is suspected to affect the cardiometabolic profile, e.g., liver function and serum lipids. However, only a few studies have investigated the impact of this specific exposure among firefighters.

METHODS

Men included in the CELSPAC-FIREexpo study were professional firefighters (n = 52), newly recruited firefighters in training (n = 58), and controls (n = 54). They completed exposure questionnaires and provided 1-3 samples of urine and blood during the 11-week study period to allow assessment of their exposure to PFAS (6 compounds) and PAHs (6 compounds), and to determine biomarkers of liver function (alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin (BIL)) and levels of serum lipids (total cholesterol (CHOL), low-density lipoprotein cholesterol (LDL) and triglycerides (TG)). The associations between biomarkers were investigated both cross-sectionally using multiple linear regression (MLR) and Bayesian weighted quantile sum (BWQS) regression and prospectively using MLR. The models were adjusted for potential confounders and false discovery rate correction was applied to account for multiplicity.

RESULTS

A positive association between exposure to PFAS and PAH mixture and BIL (β = 28.6%, 95% CrI = 14.6-45.7%) was observed by the BWQS model. When the study population was stratified, in professional firefighters and controls the mixture showed a positive association with CHOL (β = 29.5%, CrI = 10.3-53.6%) and LDL (β = 26.7%, CrI = 8.3-48.5%). No statistically significant associations with individual compounds were detected using MLR.

CONCLUSIONS

This study investigated the associations between exposure to PFAS and PAHs and biomarkers of cardiometabolic health in the Czech men, including firefighters. The results suggest that higher exposure to a mixture of these compounds is associated with an increase in BIL and the alteration of serum lipids, which can result in an unfavourable cardiometabolic profile.

Associations of polycyclic aromatic hydrocarbons, water-soluble ions and metals in PM2.5 with liver function: Evidence from schizophrenia cohort

BACKGROUND

Fine particulate matter (PM_2.5) was reported to impact liver function, but the roles of specific PM_2.5 chemical components remained to be explored. Besides, severe liver dysfunction in schizophrenia patients deserves attention.

OBJECTIVE

To investigate the associations of short-term PM_2.5 components with liver function in schizophrenia patients.

METHODS

A repeated-measures study based on schizophrenia cohort including 1023 visits (n = 446) was conducted during 2017-2020. Liver function was reflected by 10 indicators including liver enzymes, proteins and bilirubin et al. Monitoring data of PM_2.5 and its components, including 16 polycyclic aromatic hydrocarbons (PAHs), 4 water-soluble ions and 10 metals were collected. Linear mixed effect and Bayesian kernel machine regression (BKMR) models were used to evaluate the single and combined effects of PM_2.5 components (0-3 day) on liver function in schizophrenia patients.

RESULTS

Several PAHs were significantly associated with liver enzymes, while water-soluble ions and metal components had almost no association. Specifically, with per interquartile range (IQR) increased in Fluoranthene, levels of alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST) and gamma-glutamyl transpeptidase (GGT) increased by 2.06 %, 5.07 %, 4.94 % and 5.56 %, respectively. An IQR increases in Benzo[a]pyrene was significantly associated with 6.62 %, 3.67 % and 7.83 % increase in ALT, AST and GGT. Almost all PAHs, sulfate, nitrate, ammonium, Sb, Al, As, Pb, Mn and Tl were positively associated with albumin (ALB). Phenanthrene was associated with increased levels of direct bilirubin (DBIL) and total bilirubin (TBIL). The combined effects of significant PM_2.5 components on ALP, GGT, ALB, globulin (GLOB), ratio of albumin to globulin (A/G), TBIL and total bile acid (TBA) were found by BKMR, respectively.

CONCLUSIONS

Findings highlight the short-term combined effects of PM_2.5 components, especially PAHs, on liver function in schizophrenia patients, which contribute to the management of PM_2.5 sources including combustion activities and traffic emissions as well as improving schizophrenia comorbidities.

Sex-specific effect of urinary metabolites of polycyclic aromatic hydrocarbons on thyroid profiles: results from NHANES 2011-2012

The current study aims to evaluate the associations between 10 urinary polycyclic aromatic hydrocarbon (PAH) metabolites and thyroid profiles. The levels of 10 PAH metabolites and thyroid profiles were obtained from National Health and Nutrition Examination Survey (NHANES) 2011-2012. Spearman analysis was utilized to evaluate the correlation coefficients among these 10 PAH metabolites. Multivariate linear and logistic regression models assessed the relationship between urinary PAH metabolite levels, thyroid hormones, and thyroid autoantibodies after adjusting potential confounders. Stratified analysis by gender was performed to evaluate sex-specific effect of urinary metabolites of PAH on thyroid profiles. One thousand six hundred forty-five eligible adult participants with complete research data were enrolled. Of note, the concentrations of the majority of urinary PAH metabolites were remarkedly higher in females compared with males. 2-hydroxyfluorene (2-FLU) was associated with higher total triiodothyronine (T3) levels in whole population (β = 2.113, 95% CI 0.339-3.888). In males, positive associations were observed in 1-hydroxynaphthalene (1-NAP) and free thyroxine (T4) (β = 0.0002, 95% CI 0.0000-0.0004). 2-FLU was also found positively associated with total T3 (β = 2.528, 95% CI 0.115-4.940) in male subjects. While in female participants, 2-hydroxynaphthalene (2-NAP) was associated with free T3 (β = 0.002, 95% CI 0.000-0.005). 2-FLU was associated with total T3 (β = 2.683, 95% CI 0.038-5.328), free T3 (β = 0.050, 95% CI 0.012-0.087), and total T4 (β = 0.195, 95% CI 0.008-0.382). 2-Hydroxyphenanthrene (2-OHP), 1-hydroxypyrene (1-HP), and 9-hydroxyfluorene (9-FLU) were all positively related to total T3 levels, and the corresponding coefficients were 16.504, 6.587, and 3.010. 9-FLU was also associated with free T3 (β = 0.049, 95% CI 0.008-0.090). No statistical significances were found between PAH metabolite levels and increased prevalence of increased thyroglobulin antibody (TgAb)/thyroid peroxidase antibody (TPOAb) when PAH metabolites were treated as continuous variables. Meanwhile, in the quartile analyses, increased prevalence of elevated TgAb was observed in participants with quartile 2 2-NAP compared with lowest quartile (OR = 1.753, 95% CI 1.021-3.008). Male subgroup analyses indicated that increased prevalence of elevated TgAb was observed in higher quartile of 1-NAP, 2-NAP, and 3-hydroxyfluorene (3-FLU). Increased prevalence of elevated TPOAb was associated with higher 2-NAP quartile. However, in subgroup analysis of females, no statistical significances were found between PAH quartiles and increased TgAb/TPOAb. Significant correlations were found among these 10 PAH metabolites. In conclusion, the cross-sectional study indicated that exposure to PAH might disturb the concentrations of thyroid hormones and thyroid autoantibodies. It is noteworthy that significant differences existed in males and females. Further prospective research is warranted to explore the causal relationship and underlying mechanism of PAH exposure on thyroid dysfunction.

Exposure to volatile organic compounds and polycyclic aromatic hydrocarbons is associated with the risk of non-alcoholic fatty liver disease in Korean adolescents: Korea National Environmental Health Survey (KoNEHS) 2015-2017

Non-alcoholic fatty liver disease (NAFLD) is one of the most frequent liver diseases among adolescents. Several animal studies have suggested that volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) increase NAFLD risk. However, few epidemiological studies have confirmed the association between VOCs, PAHs and NAFLD in the general adolescent population. Therefore, we analyzed 798 adolescents from the Korean National Environmental Health Survey (KoNEHS), 2015-2017, to examine the associations of urinary metabolites of VOCs and PAHs with serum alanine aminotransferase (ALT) activity and NAFLD prevalence. We performed linear regression, logistic regression, and Bayesian kernel machine regression (BKMR) to evaluate the association of urinary VOCs and PAHs metabolites with ALT levels and NAFLD prevalence. After adjusting for all covariates, urinary benzylmercapturic acid and 2-hydroxyfluorene levels were found to increase ALT activity and NAFLD prevalence. Additionally, the BKMR analyses showed a significantly positive overall effect on ALT activity and NAFLD prevalence with urinary concentrations of VOCs and PAHs metabolites, with 2-hydroxyfluorene as the biggest contributor. Our study suggests that exposure to low-level VOCs and PAHs may have a detrimental effect on NAFLD risk in adolescents. Given the increasing prevalence of NAFLD in adolescents, future cohort studies are confirmed to comprehend the effect of these chemicals on NAFLD risk.

The association between urinary polycyclic aromatic hydrocarbon metabolites and liver function among US population: a cross-sectional study

Most studies have focused on the pulmonary toxicity of inhaled PAHs to date; therefore, their hepatotoxic consequences are yet unknown. The main aim of this study is to examine the association between urinary polycyclic aromatic hydrocarbons (PAHs) and liver function parameters among the US population. The data included in this study were from the National Health and Nutritional Examination Survey (NHANES) 2003-2016. Finally, we included 2515 participants from seven cycles of the NHANES. Logistic regression was performed to calculate the association between each PAH and liver function parameters (elevated vs. normal) with odds ratio (OR) and 95% confidence intervals (CIs), along with adjustment for confounding variables. P < 0.05 was considered to indicate a statistically significant difference. All analyses were performed using R software 4.0.1. In the present study, all 2515 individuals were aged ≥ 18 years, 1211 males, and 1304 females. The average age normal was 45.56 ± 20.20, and the elevated was 46.04 ± 19.73 years, respectively. The results of logistic regression indicated that increased 9-hydroxyfluorene (OR  = 2.11, 95% CI = [1.52, 2.95], P < 0.001), 2-hydroxyfluorene (OR  = 1.61, 95% CI = [1.23, 2.11], P < 0.001), and 3-hydroxyfluorene (OR  = 1.54, 95% CI = [1.21, 1.95], P < 0.001) were associated with elevated GGT. In conclusion, 9-hydroxyfluorene is associated with elevated GGT level, and the effect of 9-hydroxyfluorene on GGT is modified by other PAHs, which means that 9-hydroxyfluorene has a greater influence on GGT when other PAHs are increased.

Constitutive androstane receptor (CAR) mediates pyrene-induced mice liver inflammatory response with increased serum amyloid A proteins and Th17 cells

BACKGROUND AND PURPOSE

The constitutive androstane receptor (CAR), a known xenobiotic sensor, plays an important role in drug metabolism by regulating numerous genes. We previously reported that pyrene, an environmental pollutant, is a CAR activator and induces mouse hepatotoxicity via CAR. Here, we investigate the molecular mechanism of inflammatory response in pyrene-caused mice liver injury.

EXPERIMENTAL APPROACH

Effects of pyrene on the liver were investigated in wild-type and CAR knockout (KO) mice. Levels of pyrene and its metabolite were analyzed by high performance liquid chromatography (HPLC).

KEY RESULTS

Serum amyloid A proteins (SAAs) were dramatically induced in the liver and serum of pyrene-exposed wild-type mice. Interleukin 17 (IL-17)-producing helper T cells (Th17 cells) and IL-17 levels were significantly increased in the liver of pyrene-exposed wild-type mice. Hepatic mRNA levels of inflammatory cytokines including IL-1β, IL-6 and TNFα, and serum IL-6 levels were significantly elevated in pyrene-treated wild-type mice. However, the above induction was not observed in CAR KO mice.

CONCLUSION AND IMPLICATIONS

We demonstrate that CAR plays a crucial role in pyrene-caused mice liver inflammatory response with increased SAAs and Th17 cells. Our results suggest that serum SAAs may be a convenient biomarker for early diagnosis of liver inflammatory response caused by polycyclic aromatic hydrocarbons (PAHs) including pyrene. CAR and Th17 cells may be potential targets for novel therapeutic strategy for xenobiotic-induced liver inflammatory response.

Insights into the hepatotoxicity of pyrene and 1-chloropyrene using an integrated approach of metabolomics and transcriptomics

The toxicity of pyrene (Pyr) and its chlorinated species have not be comprehensively and clearly elucidated. In this study, an integrated approach of metabolomics and transcriptomics were applied to evaluate the hepatotoxicity of Pyr and 1-chloropyrene (1-Cl-Pyr) at human exposure level, using human L02 hepatocytes. After 24 h exposure to Pyr and 1-Cl-Pyr at 5-500 nM, cell viability was not significantly changed. Transcriptomics results showed that exposure to Pyr and 1-Cl-Pyr at 5 and 50 nM obviously altered the gene expression profiles, but did not significantly induce the expression of genes strongly related to the activation of aryl hydrocarbon receptor (AhR), such as CYP1A1, CYP1B1, AHR, ARNT. Pyr and 1-Cl-Pyr both induced a notable metabolic perturbation to L02 cells. Glycerophospholipid metabolism was found to be the most significantly perturbed pathway after exposure to Pyr and 1-Cl-Pyr, indicating their potential damage to the cell membrane. The other significantly perturbed pathways were identified to be oxidative phosphorylation (OXPHOS), glycolysis, and fatty acid β oxidation, all of which are related to energy production. Exposure to Pyr at 5 and 50 nM induced the up-regulation of fatty acid β oxidation and OXPHOS. The similar result was observed after exposure to 5 nM 1-Cl-Pyr. In contrast, exposure to 50 nM 1-Cl-Pyr induced the down-regulation of OXPHOS by inhibiting the activity of complex I. The obtained results suggested that the modes of action of Pyr and 1-Cl-Pyr on energy production remarkably varied not only with molecular structure change but also with exposure concentration.

Long-term exposure to environmental level of phenanthrene causes adaptive immune response and fibrosis in mouse kidneys

As ubiquitous, persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) have adverse impacts on human health. Phenanthrene (Phe) is one of the most abundant PAHs in the environment. However, the long-term effects of exposure to environmental level of Phe on the kidneys and the potential mechanisms are unclear. T helper (Th) cells, a subtype of CD4⁺ T cells that play a central role in the renal immune microenvironment. In this study, male mice were chronically exposed to 5, 50, and 500 ng/kg bw Phe every other day for total 210 days. Those results indicated that environmental Phe exposure caused kidney hypertrophy, injury and fibrosis in the mice. Chronic, long-term environmental level of Phe exposure did not significantly alter the innate immune response but induced adaptive immune response changes (Th1/Th2 related cytokines release), causing a type 1 immune response in the 5 ng/kg bw Phe group and a type 2 immune response in the high dose groups (50 and 500 ng/kg bw). This study provides novel insights into the roles of adaptive immune response in long-term PAH exposure-induced chronic kidney injury and fibrosis, which is beneficial for further understanding the potential health hazards of PAHs and providing new avenues for immune intervention strategies to alleviate PAHs toxicity.

Chrysene, a four-ring polycyclic aromatic hydrocarbon, induces hepatotoxicity in mice by activation of the aryl hydrocarbon receptor (AhR)

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic global environmental pollutants and cause harmful effects on human health. Here, we evaluated adverse effects of chrysene, which is a four-ring PAH and an important member of 16 priority PAHs, on the liver. Chrysene was detected in some common raw and cooked Chinese food samples. Hepatotoxicity including increased relative liver weight, hepatocyte swelling and degeneration, and elevated serum alanine aminotransferase (ALT) levels were observed in chrysene-exposed C57BL/6 mice. Glutamine treatment effectively ameliorated chrysene-induced mice liver injury by decreasing serum ALT levels. Chrysene induced mice hepatic glutathione depletion and oxidative DNA damage with increased 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. Hepatic expression levels of the aryl hydrocarbon receptor (AhR), AhR-related target genes including CYP1A1, CYP1A2 and CYP1B1, and AhR nuclear translocator (ARNT) were significantly increased in chrysene-exposed C57BL/6 mice. Chrysene induced mice hepatic mRNA levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2-mediated phase II detoxifying and antioxidant enzymes including NQO1, UGT1A1, UGT1A6, SULT1A1, GSTm1, GSTm3, Catalase (CAT), GPx1, and SOD2. We found that chrysene had toxic effects including increased relative liver weight and elevated serum ALT levels on AhR^+/+ mice but not AhR^-/- mice. Chrysene significantly induced hepatic mRNA levels of CYP1A1 and CYP1A2 in AhR^+/+ mice but not AhR^-/- mice. To our knowledge, this study is the first to demonstrate that hepatotoxicity causes by chrysene is dependent on AhR, and Nrf2 plays an important regulation role in protection against oxidative liver injury induced by chrysene.

Urinary biomarkers of polycyclic aromatic hydrocarbons and their associations with liver function in adolescents

Associations between polycyclic aromatic hydrocarbons (PAHs) and respiratory diseases have been widely studied, but the effects of PAH on liver toxicity in adolescents are unclear. Here, 3194 adolescents with NHANES data from 2003 to 2016 were selected. PAH exposure was assessed by measuring PAH metabolites in urine. The outcome variables were the levels of alanine aminotransferase (ALT), aspartate amino transferase (AST) and gamma-glutamyl transpeptidase (GGT). The association between PAH exposure and liver function was evaluated by the weighted quantile sum (WQS) and logistic regression, and the associations between PAHs and inflammation and blood lipids were evaluated by linear regression. Covariates were adjusted for age, ethnicity, BMI, physical activity, family income, cotinine, and urinary creatinine. The results showed that for females, mixed PAH exposure was related to an increased ALT level (OR = 2.33, 95% CI 1.15, 4.72), and 2-fluorene contributed the most (38.6%). Urinary 2-fluorene was positively associated with an elevated ALT level (OR = 2.19 95% 1.12, 4.27, p for trend = 0.004). Mechanistically, 2-fluorene can cause a 3.56% increase in the white blood cell count, a 6.99% increase in the triglyceride level, and 1.70% increase in the total cholesterol level. PAHs may have toxic effects, possibly mediated by inflammation and blood lipids, on the adolescent female liver. Additional confirmatory studies are needed.

Markers involved in proinflammatory effects by environmental toxicants

Toxicological studies have identified polycyclic aromatic hydrocarbons (PAH) in human breast milk, smoked and barbequed food, although the largest contribution of PAH intake into the body are cereals and cereals products. The major effects attributable to PAH appeared to occur in the liver, lungs, the hematopoietic system, and the kidney. Nevertheless, more precise mechanisms by which PAH initiates its pathological features are not fully understood. In the present study, we evaluated levels of myeloperoxidase activity, its association with nitric oxide synthesis (NO), levels of uric acid (UA) in circulating blood and glucose in female rats exposed to environmental toxicants. A higher concentration of hydrogen peroxide activates myeloperoxidase, which acts as a leucocyte attractant, contributing to enhanced iNOS activity. In parallel, uric acid in addition to its pro-inflammatory effects aggravates insulin resistance and hyperglycemia, which worsens the process. Our findings suggest potential intermediate mechanisms involved in the inflammatory effects of PAH, which might give insight for the involvement of environmental toxicants not only in carcinogenesis but also in its association with acute cardiovascular disease and induction of multi-organ damage. The development of iNOS inhibitors might be beneficial in certain inflammatory disorders.

Gestational 1-nitropyrene exposure causes gender-specific impairments on postnatal growth and neurobehavioral development in mice

1-Nitropyrene (1-NP), a typical nitrated polycyclic aromatic hydrocarbon, is widely distributed in the environment and is well known for its mutagenic effects. Recently, we found that gestational 1-NP exposure induced fetal growth restriction. In this study, we further evaluated the effect of in utero 1-NP exposure on postnatal growth and neurobehavioral development in the offspring. Pregnant mice were administered with 1-NP (10 μg/kg) by gavage daily in late pregnancy (GD13-GD17). The body weight of each offspring was measured from PND1 to 12 weeks postpartum. Exploration and anxiety related activities were detected by open-field test at 6 weeks postpartum. Learning and memory were assessed by Morris Water Maze at 7 weeks postpartum. And depressive-like behaviors were estimated by sucrose preference test at 10 weeks postpartum. Significant body weight reduction was observed in 1-NP-exposed female offspring at PND1, PND14 and PND21 while the lower body weight was only found at PND1 for 1-NP-exposed male offspring. Exploration and anxiety activities at puberty, and depressive-like behavior in adulthood were not disturbed in offspring prenatally exposed to 1-NP. Interestingly, spatial learning and memory ability at puberty was impaired in females but not in males prenatally exposed to 1-NP. These findings suggest that gestational 1-NP exposure delays postnatal growth and impaired neurobehavioral development in a gender-dependent manner.