A sandwich enzyme-linked immunosorbent assay for adducts of polycyclic aromatic hydrocarbons with human serum albumin

Environmental exposure to polycyclic aromatic hydrocarbons: An underestimated risk factor for systemic lupus erythematosus onset and progression

OBJECTIVE

To investigate the link between systemic lupus erythematosus (SLE) incidence and exposure to environmental polycyclic aromatic hydrocarbons (PAH).

METHODS

A case-control study (ChiCTR2000038187) involving 316 SLE patients and 851 healthy controls (HCs) was executed. Environmental exposure was assessed via a questionnaire, stratified by gender and age (females <35 and ≥35 years, males). Blood samples collected from 89 HCs, 85 inactive, and 95 active SLE patients were used to measure serum benzo[a]pyrene diol epoxide -albumin (BPDE-Alb) adducts and PAH concentrations, indicating long-term and short-term exposure respectively. Intergroup comparisons and statistical analyses were conducted using R version 4.3.1.

RESULTS

Diverse patterns were found in how environmental factors affect SLE onset across different demographics. Lifestyle exposure factors were found to be a stronger determinant of SLE onset than occupational exposure factors in women under 35. Indoor air pollution had a significant impact on SLE incidence, potentially comparable to outdoor air pollution. Lifestyle-related PAH exposure had a greater impact on SLE than occupational PAH exposure. PAH exposure levels progressively increase from HCs to inactive and active SLE patients. Active SLE patients show markedly higher BPDE-Alb levels than HCs.

CONCLUSIONS

Environmental PAH, particularly lifestyle-related, are significant, yet under-recognized, risk factors for SLE.

STATEMENT OF ENVIRONMENTAL IMPLICATION

We examined the relationship between exposure to environmental polycyclic aromatic hydrocarbons (PAH) and the incidence of systemic lupus erythematosus (SLE). PAH, prevalent in sources such as cigarette smoke, air pollution, and charred food, pose significant health hazards. This study is the first to investigate specific PAH exposure levels in SLE patients. We determined actual PAH exposure levels in both SLE patients and healthy individuals and indicated that long-term PAH exposure biomarker is more reliable for evaluating exposure in non-occupationally exposed groups like SLE, compared to short-term markers. These findings provide valuable insights for future research on similar non-occupationally exposed populations.

Decoding the exposome: data science methodologies and implications in exposome-wide association studies (ExWASs)

This paper explores the exposome concept and its role in elucidating the interplay between environmental exposures and human health. We introduce two key concepts critical for exposomics research. Firstly, we discuss the joint impact of genetics and environment on phenotypes, emphasizing the variance attributable to shared and nonshared environmental factors, underscoring the complexity of quantifying the exposome's influence on health outcomes. Secondly, we introduce the importance of advanced data-driven methods in large cohort studies for exposomic measurements. Here, we introduce the exposome-wide association study (ExWAS), an approach designed for systematic discovery of relationships between phenotypes and various exposures, identifying significant associations while controlling for multiple comparisons. We advocate for the standardized use of the term "exposome-wide association study, ExWAS," to facilitate clear communication and literature retrieval in this field. The paper aims to guide future health researchers in understanding and evaluating exposomic studies. Our discussion extends to emerging topics, such as FAIR Data Principles, biobanked healthcare datasets, and the functional exposome, outlining the future directions in exposomic research. This abstract provides a succinct overview of our comprehensive approach to understanding the complex dynamics of the exposome and its significant implications for human health.

Lung cancer risk in workers occupationally exposed to polycyclic aromatic hydrocarbons with emphasis on the role of DNA repair gene

OBJECTIVE

Workers in secondary aluminum production plants are occupationally exposed to polycyclic aromatic hydrocarbons (PAHs). We aimed to monitor the concentrations of PAHs in air and in serum of workers at two secondary aluminum production plants. We also investigated the potential risk of lung cancer development among PAHs exposed workers with emphasis on the role of A1AT mutation and APEX1 gene polymorphisms.

METHODS

This study included 177 workers from administrative departments and production lines. Blood samples were obtained for estimation of benzo(a)pyrene diol epoxide albumin adduct (BPDE-Alb adduct), anti-Cyclin-B1 marker (CCNB1) and squamous cell carcinoma antigen (SCCAg). Genes' polymorphism for human apurinic/apyrimidinic endonuclease (APEX1) and alpha-1-anti-trypsin (A1AT) gene mutation were detected.

RESULTS

There was a significant increase in the level of BPDE-Alb adduct among exposed workers in comparison to non-exposed group. Moreover, 41.67% of exposed workers in El Tebbin had BPDE-Alb adduct level ≥ 15 ng/ml versus 29.6% of workers in Helwan factory. There was a significant increase in tumor markers (SCCAg and CCNB1) among workers whose BPDE-Alb adduct ≥ 15 ng/ml. There was a significant increase in the level of BPDE-Alb adducts in exposed workers carrying homozygous APEX1 genotype Glu/Glu. Furthermore, exposed workers with the Glu/Glu genotype had high tumor markers levels. There was a significant increase in levels of BPDE-Alb adducts in workers carrying A1AT mutant allele. Moreover, workers with mutant A1AT genotype had significantly high tumor markers (SCCAg and CCNB1) levels.

CONCLUSION

Therefore, we conclude that aluminum workers may be at a potential risk of lung cancer development due to PAHs exposure. Although PAHs concentrations in air were within the permissible limits, yet evidence of DNA damage was present as expressed by high BPDE-albumin adduct level in exposed workers. Also, elevation of tumor markers (SCCAg and CCNB1) in exposed workers points to the importance of periodic biological monitoring of such workers to protect them from cancer risk.

Pathways to Identify Electrophiles In Vivo Using Hemoglobin Adducts: Hydroxypropanoic Acid Valine Adduct and Its Possible Precursors

Analytical methods and tools for the characterization of the human exposome by untargeted mass spectrometry approaches are advancing rapidly. Adductomics methods have been developed for untargeted screening of short-lived electrophiles, in the form of adducts to proteins or DNA, in vivo. The identification of an adduct and its precursor electrophile in the blood is more complex than that of stable chemicals. The present work aims to illustrate procedures for the identification of an adduct to N-terminal valine in hemoglobin detected with adductomics, and pathways for the tracing of its precursor and possible exposure sources. Identification of the adduct proceeded via preparation and characterization of standards of adduct analytes. Possible precursor(s) and exposure sources were investigated by measurements in blood of adduct formation by precursors in vitro and adduct levels in vivo. The adduct was identified as hydroxypropanoic acid valine (HPA-Val) by verification with a synthesized reference. The HPA-Val was measured together with other adducts (from acrylamide, glycidamide, glycidol, and acrylic acid) in human blood (n = 51, schoolchildren). The HPA-Val levels ranged between 6 and 76 pmol/g hemoglobin. The analysis of reference samples from humans and rodents showed that the HPA-Val adduct was observed in all studied samples. No correlation of the HPA-Val level with the other studied adducts was observed in humans, nor was an increase in tobacco smokers observed. A small increase was observed in rodents exposed to glycidol. The formation of the HPA-Val adduct upon incubation of blood with glycidic acid (an epoxide) was shown. The relatively high adduct levels observed in vivo in relation to the measured reactivity of the epoxide, and the fact that the epoxide is not described as naturally occurring, suggest that glycidic acid is not the only precursor of the HPA-Val adduct identified in vivo. Another endogenous electrophile is suspected to contribute to the in vivo HPA-Val adduct level.

Effects of Aging and Disease Conditions in Brain of Tumor-Bearing Mice: Evaluation of Purine DNA Damages and Fatty Acid Pool Changes

The consequences of aging and disease conditions in tissues involve reactive oxygen species (ROS) and related molecular alterations of different cellular compartments. We compared a murine model of immunodeficient (SCID) xenografted young (4 weeks old) and old (17 weeks old) mice with corresponding controls without tumor implantation and carried out a compositional evaluation of brain tissue for changes in parallel DNA and lipids compartments. DNA damage was measured by four purine 5',8-cyclo-2'-deoxynucleosides, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), and 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxo-dA). In brain lipids, the twelve most representative fatty acid levels, which were mostly obtained from the transformation of glycerophospholipids, were followed up during the aging and disease progressions. The progressive DNA damage due to age and tumoral conditions was confirmed by raised levels of 5'S-cdG and 5'S-cdA. In the brain, the remodeling involved a diminution of palmitic acid accompanied by an increase in arachidonic acid, along both age and tumor progressions, causing increases in the unsaturation index, the peroxidation index, and total TFA as indicators of increased oxidative and free radical reactivity. Our results contribute to the ongoing debate on the central role of DNA and genome instability in the aging process, and on the need for a holistic vision, which implies choosing the best biomarkers for such monitoring. Furthermore, our data highlight brain tissue for its lipid remodeling response and inflammatory signaling, which seem to prevail over the effects of DNA damage.

Utilizing a Biology-Driven Approach to Map the Exposome in Health and Disease: An Essential Investment to Drive the Next Generation of Environmental Discovery

BACKGROUND

Recent developments in technologies have offered opportunities to measure the exposome with unprecedented accuracy and scale. However, because most investigations have targeted only a few exposures at a time, it is hypothesized that the majority of the environmental determinants of chronic diseases remain unknown.

OBJECTIVES

We describe a functional exposome concept and explain how it can leverage existing bioassays and high-resolution mass spectrometry for exploratory study. We discuss how such an approach can address well-known barriers to interpret exposures and present a vision of next-generation exposomics.

DISCUSSION

The exposome is vast. Instead of trying to capture all exposures, we can reduce the complexity by measuring the functional exposome-the totality of the biologically active exposures relevant to disease development-through coupling biochemical receptor-binding assays with affinity purification-mass spectrometry. We claim the idea of capturing exposures with functional biomolecules opens new opportunities to solve critical problems in exposomics, including low-dose detection, unknown annotations, and complex mixtures of exposures. Although novel, biology-based measurement can make use of the existing data processing and bioinformatics pipelines. The functional exposome concept also complements conventional targeted and untargeted approaches for understanding exposure-disease relationships.

CONCLUSIONS

Although measurement technology has advanced, critical technological, analytical, and inferential barriers impede the detection of many environmental exposures relevant to chronic-disease etiology. Through biology-driven exposomics, it is possible to simultaneously scale up discovery of these causal environmental factors. https://doi.org/10.1289/EHP8327.

Effects of polycyclic aromatic hydrocarbons and multiple metals co-exposure on the mosaic loss of chromosome Y in peripheral blood

Mosaic loss of chromosome Y (mLOY) is an indicator of genome instability, but the environmental stressors of mLOY remained largely unknown. In this study, we detected the internal exposure levels of 11 polycyclic aromatic hydrocarbon (PAH) metabolites and 22 metals among 888 coke-oven workers, and calculated their blood mLOY based on genome-wide SNP genotyping data and presented as median log R ratio (mLRR-Y). The generalized linear model (GLM), LASSO, and Bayesian kernel machine regression (BKMR), were used to select mLOY-relevant chemicals. The results of these models consistently suggested the negative dose-response relationships of urinary 1-hydroxynaphthalene (1-OHNa), antimony (Sb), and molybdenum (Mo) with mLRR-Y. There were no pairwise interactions between these three chemicals (P_interaction > 0.05), but subjects with high exposure to ≥ 2 kinds of these chemicals showed reducing mLRR-Y [β(95%CI) = - 0.015(- 0.023, - 0.008)], increasing oxidative DNA damage (marked by 8-hydroxydeoxyguanosine) [β(95%CI) = 0.625(0.454, 0.796)] and chromosome damage (marked by micronucleus frequency in lymphocytes) [frequency ratio (FR) and 95%CI = 1.146(1.047, 1.225)] than those with low exposure to all these chemicals. The combined effects of 1-OHNa, Sb, and Mo on elevating DNA damage may partly explain their joint effects on increased blood mLOY. These results provided a new insight into environmental hazards co-exposure on chromosome-Y deletions.

On the relevance of hydroxyl radical to purine DNA damage

Hydroxyl radical (HO^•) is the most reactive toward DNA among the reactive oxygen species (ROS) generated in aerobic organisms by cellular metabolisms. HO^• is generated also by exogenous sources such as ionizing radiations. In this review we focus on the purine DNA damage by HO^• radicals. In particular, emphasis is given on mechanistic aspects for the various lesion formation and their interconnections. Although the majority of the purine DNA lesions like 8-oxo-purine (8-oxo-Pu) are generated by various ROS (including HO^•), the formation of 5',8-cyclopurine (cPu) lesions in vitro and in vivo relies exclusively on the HO^• attack. Methodologies generally utilized for the purine lesions quantification in biological samples are reported and critically discussed. Recent results on cPu and 8-oxo-Pu lesions quantification in various types of biological specimens associated with the cellular repair efficiency as well as with distinct pathologies are presented, providing some insights on their biological significance.

Polycyclic aromatic hydrocarbons exposure and their joint effects with age, smoking, and TCL1A variants on mosaic loss of chromosome Y among coke-oven workers

Mosaic loss of chromosome Y (mLOY) is the most common structure somatic event that related to increased risks of various diseases and mortality. Environmental pollution and genetic susceptibility were important contributors to mLOY. We aimed to explore the associations of polycyclic aromatic hydrocarbons (PAHs) exposure, as well as their joint effects with age, smoking, and genetic variants on peripheral blood mLOY. A total of 1005 male coke-oven workers were included in this study and their internal PAHs exposure levels of 10 urinary PAH metabolites and plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts were measured. mLOY was defined by the median log R ratio(mLRR) of 1480 probes in male-specific region of chromosome-Y from genotyping array. We found that the PAHs exposure levels were linearly associated with mLOY. A 10-fold increase in urinary 1-hydroxynaphthalene (1-OHNa), 1-hydroxyphenanthrene (1-OHPh), 2-OHPh, 1-hydroxypyrene (1-OHP), ΣOH-PAHs, and plasma BPDE-Alb adducts could generate 0.0111, 0.0085, 0.0069, 0.0103, 0.0134, and 0.0152 decrease in mLRR-Y, respectively. Additionally, mLOY accelerated with age, smoking pack-years, and TCL1A rs1122138-C allele, and we observed the most severe mLOY among subjects carrying more than 3 of the above risk factors. Our results revealed the linear dose-effect associations between PAHs exposure and mLOY. Elder male smokers carrying rs1122138CC genotype were the most susceptible subpopulations to mLOY, who should be given protections for PAHs exposure induced chromosome-Y aberration.

Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry

This article describes the optimization of methodology for extending the measurement of volatile organic compounds (VOCs) to increasingly heavier polycyclic aromatic hydrocarbons (PAHs) with a detailed focus on recent sorbent tube technology. Although PAHs have lower volatility than compounds such as benzene, toluene, ethylbenzene and xylenes, these semi-volatile compounds can be detected in air and breath samples. For this work, PAHs were captured on sorbent tubes and subsequently analyzed using automated thermal desorption gas chromatography - mass spectrometry (ATD-GC/MS). While many different sorbent tubes are commercially available, optimization for airborne PAH sampling using sorbent tubes has not been previously considered. Herein, several commercially available sorbent tubes, including Carbograph 2 TD/1TD, Tenax TA, XRO-440, and inert-coated PAH tubes are compared to determine the relative recovery for eight PAHs commonly found in the environment. Certain types of sorbent materials were found to be better suited for PAH recovery during thermal desorption, and PAH reaction products were observed on several types of sorbent tubes, including graphitized carbon black sorbents with stainless steel tube materials. As such, selection of sorbent tube media should be carefully considered prior to embarking on a PAH study.

Metabolomic assessment of exposure to near-highway ultrafine particles

Exposure to traffic-related air pollutants has been associated with increased risk of adverse cardiopulmonary outcomes and mortality; however, the biochemical pathways linking exposure to disease are not known. To delineate biological response mechanisms associated with exposure to near-highway ultrafine particles (UFP), we used untargeted high-resolution metabolomics to profile plasma from 59 participants enrolled in the Community Assessment of Freeway Exposure and Health (CAFEH) study. Metabolic variations associated with UFP exposure were assessed using a cross-sectional study design based upon low (mean 16,000 particles/cm3) and high (mean 24,000 particles/cm3) annual average UFP exposures. In comparing quantified metabolites, we identified five metabolites that were differentially expressed between low and high exposures, including arginine, aspartic acid, glutamine, cystine and methionine sulfoxide. Analysis of the metabolome identified 316 m/z features associated with UFP, which were consistent with increased lipid peroxidation, endogenous inhibitors of nitric oxide and vehicle exhaust exposure biomarkers. Network correlation analysis and metabolic pathway enrichment identified 38 pathways and included variations related to inflammation, endothelial function and mitochondrial bioenergetics. Taken together, these results suggest UFP exposure is associated with a complex series of metabolic variations related to antioxidant pathways, in vivo generation of reactive oxygen species and processes critical to endothelial function.

Dietary Bovine Lactoferrin Reduces Staphylococcus aureus in the Tissues and Modulates the Immune Response in Piglets Systemically Infected with S. aureus

BACKGROUND

Bovine lactoferrin (bLf) reduces Staphylococcus aureus infection in premature infants and promotes the growth of Bifidobacterium infantis, a predominant infant gut species. We hypothesized that bLf in combination with B. infantis would reduce the severity of systemic S. aureus infection.

OBJECTIVE

The aim was to determine the effects of oral administration of bLf and B. infantis on the course of systemic S. aureus infection.

METHODS

Colostrum-deprived piglets were fed formulas containing 4 g whey/L (CON group) or bLf (LF group). One-half of the piglets in each group were gavaged with B. infantis (109 colony-forming units/d), resulting in 2 additional groups (BI or COMB, respectively). On day 7, piglets were intravenously injected with S. aureus. Blood samples were collected preinfection and every 12 h postinfection for immune analyses. Tissue samples were collected on day 12 for analysis of bacterial abundance and gene expression.

RESULTS

Preinfection, LF piglets had lower serum interleukin 10 (IL-10), a higher percentage of lymphocytes, and a lower percentage of neutrophils than BI or COMB piglets. After infection, dietary bLf increased piglet weight gain, reduced staphylococcal counts in the kidneys, and tended to lower staphylococcal counts in the lungs and heart. Dietary bLf also decreased kidney IL-10 and increased lung interferon γ (IFN-γ) mRNA. B. infantis increased splenic IFN-γ expression. Renal Toll-like receptor 2 was upregulated in BI piglets but not in COMB piglets. Postinfection, BI piglets had increased serum IL-10 and decreased memory T cell populations. LF and COMB piglets had fewer circulating monocytes and B cells than CON or BI piglets.

CONCLUSIONS

Dietary bLf and B. infantis produced independent and tissue-specific effects. Piglets fed bLf alone or in combination with B. infantis mounted a more effective immune response and exhibited lower bacterial abundance. This study provides biological underpinnings to the clinical benefits of bLf observed in preterm infants but does not support B. infantis administration during S. aureus infection.

Interaction of benzo[a]pyrene diol epoxide isomers with human serum albumin: Site specific characterisation of adducts and associated kinetics

Carcinogenicity of benzo[a]pyrene {B[a]P, a polycyclic aromatic hydrocarbon (PAH)} involves DNA-modification by B[a]P diol epoxide (BPDE) metabolites. Adducts to serum albumin (SA) are not repaired, unlike DNA adducts, and therefore considered advantageous in assessment of in vivo dose of BPDEs. In the present work, kinetic experiments were performed in relation to the dose (i.e. concentration over time) of different BPDE isomers, where human SA (hSA) was incubated with respective BPDEs under physiological conditions. A liquid chromatography (LC) tandem mass spectrometry methodology was employed for characterising respective BPDE-adducts at histidine and lysine. This strategy allowed to structurally distinguish between the adducts from racemic anti- and syn-BPDE and between (+)- and (-)-anti-BPDE, which has not been attained earlier. The adduct levels quantified by LC-UV and the estimated rate of disappearance of BPDEs in presence of hSA gave an insight into the reactivity of the diol epoxides towards the N-sites on SA. The structure specific method and dosimetry described in this work could be used for accurate estimation of in vivo dose of the BPDEs following exposure to B[a]P, primarily in dose response studies of genotoxicity, e.g. in mice, to aid in quantitative risk assessment of PAHs.

Essential Metals Zinc, Selenium, and Strontium Protect against Chromosome Damage Caused by Polycyclic Aromatic Hydrocarbons Exposure

Essential metals play important roles in maintaining cellular homeostasis, but the effects of their interaction with the environmental pollutants are still not very well-known in human subjects. The aim of this study was to evaluate the roles of essential metals and their interactions with polycyclic aromatic hydrocarbons (PAHs) on chromosome damage, an early carcinogenic event. A total of 1245 male workers were included in this study and the levels of 11 urinary essential metals, 12 urinary PAH metabolites, plasma concentrations of benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, and lymphocyte micronucleus (MN) frequencies were monitored. We found that zinc (Zn), selenium (Se), and strontium (Sr) have significant inverse dose-response relationships with MN frequencies (all P < 0.05). Furthermore, the protective roles of Zn, Se, and Sr were mainly shown among subjects with high levels of BPDE-Alb adducts. Significant effect modification of BPDE-Alb adducts on the associations of Zn, Se, and Sr with MN frequencies was observed (all Pinteraction < 0.05). Our study showed evidence that Zn, Se, and Sr play protective roles in reducing chromosome damage, and these effects can be modified by PAH exposure levels. These findings add potential evidence for the preventive effects of Zn, Se, and Sr against carcinogenesis in human subjects.

The interaction of APEX1 variant with polycyclic aromatic hydrocarbons on increasing chromosome damage and lung cancer risk among male Chinese

Polycyclic aromatic hydrocarbons (PAHs) are the most significant contributors to tobacco-induced lung carcinogenesis. Apurinic/apyrimidinic endonuclease 1 (APE1) is a central enzyme in the removal of apurinic/apyrimidinic sites caused by DNA damaging agents. This study aimed to investigate the potential interaction of APEX1 polymorphisms and PAHs on genetic damage and lung cancer risk among male Chinese. We recruited an occupational cohort of 922 male coke oven workers and determined their DNA damage levels by calculating the lymphocytic micronucleus (MN) frequencies. Two well-studied APEX1 polymorphisms (-307A > C and Asp148Glu) and their associations with MN frequencies were examined. The impact of MN-related single nucleotide polymorphism (SNP) on lung cancer risk was further investigated in two case-control studies including 1634 male lung cancer patients and 1678 controls. It was shown that, the APEX1 148Glu allele was associated with significantly higher MN frequencies than 148Asp allele, with strongest associations among the highest PAH-exposure workers (P = 0.008). The APEX1 148Glu allele was also associated with increased lung cancer risk among male smokers, especially among heavy smokers in both case-control studies (odd ratio: 4.40, 95%CI: 3.29-5.72). In addition, APEX1 148Glu variant interacts with smoking in increasing male lung cancer risk, as measured by the attributable proportion due to interaction, which was 0.23 (95%CI: 0.06-0.39). This study showed evidence on interaction between APEX1 148Glu variant and cigarette smoking in increasing lung cancer susceptibility among male Chinese, which may be due to the synergistic effects of APEX1 148Glu and PAHs in increasing chromosome damage levels. The results provide a new insight into gene-interactions in lung carcinogenesis.

Oxidative damage to nucleic acids and benzo(a)pyrene-7,8-diol-9,10-epoxide-DNA adducts and chromosomal aberration in children with psoriasis repeatedly exposed to crude coal tar ointment and UV radiation

The paper presents a prospective cohort study. Observed group was formed of children with plaque psoriasis (n=19) treated by Goeckerman therapy (GT). The study describes adverse (side) effects associated with application of GT (combined exposure of 3% crude coal tar ointment and UV radiation). After GT we found significantly increased markers of oxidative stress (8-hydroxy-2′-deoxyguanosine, 8-hydroxyguanosine, and 8-hydroxyguanine), significantly increased levels of benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) DNA adducts (BPDE-DNA), and significantly increased levels of total number of chromosomal aberrations in peripheral lymphocytes. We found significant relationship between (1) time of UV exposure and total number of aberrated cells and (2) daily topical application of 3% crude coal tar ointment (% of body surface) and level of BPDE-DNA adducts. The findings indicated increased hazard of oxidative stress and genotoxic effects related to the treatment. However, it must be noted that the oxidized guanine species and BPDE-DNA adducts also reflect individual variations in metabolic enzyme activity (different extent of bioactivation of benzo[a]pyrene to BPDE) and overall efficiency of DNA/RNA repair system. The study confirmed good effectiveness of the GT (significantly decreased PASI score).

Women are more susceptible than men to oxidative stress and chromosome damage caused by polycyclic aromatic hydrocarbons exposure

Exposure to environmental polycyclic aromatic hydrocarbons (PAHs) has been associated with increased risk of cancer, but evidence for gender differences in this association is limited. The aim of this study was to examine the gender differences in PAHs caused early genotoxic effects such as oxidative stress and chromosome damage, which are potential carcinogenic etiology of PAHs. A total of 478 nonsmoking workers (272 men and 206 women) from a coke oven plant were recruited. We determined 16 environmental PAHs in their workplaces, and measured concentrations of 12 urinary PAH metabolites (OH-PAHs), plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, urinary 8-hydroxydeoxyguanosine (8-OHdG) and 8-iso-prostaglandin-F2α (8-iso-PGF2α), and micronucleus frequencies in lymphocytes in all subjects. It showed that, women working at the office, adjacent to the coke oven, and on the bottom or side of the coke oven displayed significantly higher levels of urinary 8-OHdG and 8-iso-PGF2α, and lymphocytic micronucleus frequencies compared with men working at above areas, respectively (all P < 0.05). These gender differences remain significant after adjusted for potential confounders and urinary ΣOH-PAHs or plasma BPDE-Alb adducts. A significant interaction existed between gender and BPDE-Alb adducts on increasing micronucleus frequencies (Pinteraction  < 0.001). We further stratified all workers by the tertiles of urinary ΣOH-PAHs or plasma BPDE-Alb adducts, and the above gender differences were more evident in the median- and high-exposure groups (all P < 0.05). In conclusion, women were more susceptible than men to oxidative stress and chromosome damage induced by PAHs, which may add potential evidence underlying gender differences in PAH exposure-related lung cacinogenesis.

Plasma microRNA expression and micronuclei frequency in workers exposed to polycyclic aromatic hydrocarbons

BACKGROUND

Ubiquitous polycyclic aromatic hydrocarbons (PAHs) have been shown to alter gene expression patterns and elevate micronuclei (MN) frequency, but the underlying mechanisms are largely unknown. MicroRNAs (miRNAs) are key gene regulators that may be influenced by PAH exposures and mediate their effects on MN frequency.

OBJECTIVES

We sought to identify PAH-associated miRNAs and evaluate their associations with MN frequency.

METHODS

We performed a two-stage study in healthy male coke oven workers to identify miRNAs associated with PAH exposures quantified using urinary monohydroxy-PAHs and plasma benzo[a]pyrene-r-7,t-8,c-10-tetrahydrotetrol-albumin (BPDE-Alb) adducts. In the discovery stage, we used Solexa sequencing to test differences in miRNA expression profiles between pooled plasma samples from 20 exposed workers and 20 controls. We then validated associations with eight selected miRNAs in 365 workers. We further evaluated associations between the PAH-associated miRNAs and MN frequency.

RESULTS

In the discovery stage, miRNA expression profiles differed between the exposed and control groups, with 68 miRNAs significantly down-regulated [fold change (FC) ≤ -5] and 3 miRNAs mildly up-regulated (+2 ≤ FC < +5) in the exposed group. In the validation analysis, urinary 4-hydroxyphenanthrene and/or plasma BPDE-Alb adducts were associated with lower miR-24-3p, miR-27a-3p, miR-142-5p, and miR-28-5p expression (p < 0.030). Urinary 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyphenanthrene, and the sum of monohydroxy-PAHs were associated with higher miR-150-5p expression (p < 0.030). These miRNAs were associated with higher MN frequency (p < 0.005), with stronger associations in drinkers (pinteraction < 0.015).

CONCLUSIONS

Associations of PAH exposures with miRNA expression, and of miRNA expression with MN frequency, suggest potential mechanisms of adverse effects of PAHs that are worthy of further investigation.

Dose-response relationships of polycyclic aromatic hydrocarbons exposure and oxidative damage to DNA and lipid in coke oven workers

Polycyclic aromatic hydrocarbons (PAHs) are known to induce reactive oxygen species and oxidative stress, but the dose-response relationships between exposure to PAHs and oxidative stress levels have not been established. In this study, we recruited 1333 male coke oven workers, monitored the levels of environmental PAHs, and measured internal PAH exposure biomarkers including 12 urinary PAH metabolites and plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, as well as the two oxidative biomarkers urinary 8-hydroxydeoxyguanosine (8-OHdG) and 8-iso-prostaglandin-F2α (8-iso-PGF2α). We found that the total concentration of urinary PAH metabolites and plasma BPDE-Alb adducts were both significantly associated with increased 8-OHdG and 8-iso-PGF2α in both smokers and nonsmokers (all p < 0.05). This exposure-response effect was also observed for most PAH metabolites (all p(trend) < 0.01), except for 4-hydroxyphenanthrene and 8-OHdG (p(trend) = 0.108). Furthermore, it was shown that only urinary 1-hydroxypyrene has a significant positive association with both 8-OHdG and 8-iso-PGF2α after a Bonferroni correction (p < 0.005). Our results indicated that urinary ΣOH-PAHs and plasma BPDE-Alb adducts can result in significant dose-related increases in oxidative damage to DNA and lipids. Furthermore, when a multianalyte method is unavailable, our findings demonstrate that urinary 1-hydroxypyrene is a useful biomarker for evaluating total PAHs exposure and assessing oxidative damage in coke oven workers.

A sandwich ELISA for measuring benzo[a]pyrene-albumin adducts in human plasma

Exposure to polycyclic aromatic hydrocarbons has often been quantified via DNA or human serum albumin (HSA) adducts of the carcinogenic metabolite benzo[a]pyrene diol epoxide (BPDE). We previously reported a sandwich ELISA, using 8E11 as capture antibody and anti-HSA as detection antibody, that detected intact BPDE adducts in HSA isolated from plasma. After confirming that BPDE binds to HSA at His146 and Lys195, we modified the ELISA to measure intact BPDE-HSA directly in human plasma. To adjust for interference due to nonspecifically bound HSA on well surfaces and to cross-reactivity of the antibodies, the ELISA employs paired wells with and without addition of BPDE tetrols to deactivate 8E11. By performing assays in quadruplicate, a series of sample-specific adjustments and screening steps are used to reduce measurement errors that are a consequence of detecting low BPDE-HSA concentrations in the general population. ELISA measurements of BPDE-HSA in plasma from smoking and nonsmoking subjects (range 0.280-2.88 ng BPDE-HSA/mg HSA) and from highway workers with and without exposure to asphalt emissions (range 0.346-13.9 ng BPDE-HSA/mg HSA) detected differences in BPDE-HSA levels in the a priori expected directions.

DNA and protein adducts in human tissues resulting from exposure to tobacco smoke

Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.