Urinary Amino-PAHs in relation to diesel engine emissions and urinary mutagenicity

Diesel exhaust has long been of health concern due to established toxicity including carcinogenicity in humans. However, the precise components of diesel engine emissions that drive carcinogenesis are still unclear. Limited work has suggested that nitrated polycyclic aromatic hydrocarbons (NPAHs) such as 1-nitropyrene and 2-nitrofluorene may be more abundant in diesel exhaust. The present study aimed to examine whether urinary amino metabolites of these NPAHs were associated with high levels of diesel engine emissions and urinary mutagenicity in a group of highly exposed workers including both smokers and nonsmokers. Spot urine samples were collected immediately following a standard work shift from each of the 54 diesel engine testers and 55 non-tester controls for the analysis of five amino metabolites of NPAHs, and cotinine (a biomarker of tobacco smoke exposure) using liquid chromatography-mass spectrometry. An overnight urine sample was collected in a subgroup of non-smoking participants for mutagenicity analysis using strain YG1041 in the Salmonella (Ames) mutagenicity assay. Personal exposure to fine particles (PM2.5) and more-diesel-specific constituents (elemental carbon and soot) was assessed for the engine testers by measuring breathing-zone concentrations repeatedly over several full work shifts. Results showed that it was 12.8 times more likely to detect 1-aminopyrene and 2.9 times more likely to detect 2-aminofluorene in the engine testers than in unexposed controls. Urinary concentrations of 1-aminopyrene were significantly higher in engine testers (p < 0.001), and strongly correlated with soot and elemental carbon exposure as well as mutagenicity tested in strain YG1041 with metabolic activation (p < 0.001). Smoking did not affect 1-aminopyrene concentrations and 1-aminopyrene relationships with diesel exposure. In contrast, both engine emissions and smoking affected 2-aminofluorene concentrations. The results confirm that urinary 1-aminopyrene may serve as an exposure biomarker for diesel engine emissions and associated mutagenicity.

Alterations to biomarkers related to long-term exposure to diesel exhaust at concentrations below occupational exposure limits in the European Union and the USA

BACKGROUND

We previously found that occupational exposure to diesel engine exhaust (DEE) was associated with alterations to 19 biomarkers that potentially reflect the mechanisms of carcinogenesis. Whether DEE is associated with biological alterations at concentrations under existing or recommended occupational exposure limits (OELs) is unclear.

METHODS

In a cross-sectional study of 54 factory workers exposed long-term to DEE and 55 unexposed controls, we reanalysed the 19 previously identified biomarkers. Multivariable linear regression was used to compare biomarker levels between DEE-exposed versus unexposed subjects and to assess elemental carbon (EC) exposure-response relationships, adjusted for age and smoking status. We analysed each biomarker at EC concentrations below the US Mine Safety and Health Administration (MSHA) OEL (<106 µg/m3), below the European Union (EU) OEL (<50 µg/m3) and below the American Conference of Governmental Industrial Hygienists (ACGIH) recommendation (<20 µg/m3).

RESULTS

Below the MSHA OEL, 17 biomarkers were altered between DEE-exposed workers and unexposed controls. Below the EU OEL, DEE-exposed workers had elevated lymphocytes (p=9E-03, false discovery rate (FDR)=0.04), CD4+ count (p=0.02, FDR=0.05), CD8+ count (p=5E-03, FDR=0.03) and miR-92a-3p (p=0.02, FDR=0.05), and nasal turbinate gene expression (first principal component: p=1E-06, FDR=2E-05), as well as decreased C-reactive protein (p=0.02, FDR=0.05), macrophage inflammatory protein-1β (p=0.04, FDR=0.09), miR-423-3p (p=0.04, FDR=0.09) and miR-122-5p (p=2E-03, FDR=0.02). Even at EC concentrations under the ACGIH recommendation, we found some evidence of exposure-response relationships for miR-423-3p (ptrend=0.01, FDR=0.19) and gene expression (ptrend=0.02, FDR=0.19).

CONCLUSIONS

DEE exposure under existing or recommended OELs may be associated with biomarkers reflective of cancer-related processes, including inflammatory/immune response.

Occupational exposure to diesel engine exhaust and serum levels of microRNAs in a cross-sectional molecular epidemiology study in China

Diesel engine exhaust (DEE) is an established lung carcinogen, but the biological mechanisms of diesel-induced lung carcinogenesis are not well understood. MicroRNAs (miRNAs) are small noncoding RNAs that play a potentially important role in regulating gene expression related to lung cancer. We conducted a cross-sectional molecular epidemiology study to evaluate whether serum levels of miRNAs are altered in healthy workers occupationally exposed to DEE compared to unexposed controls. We conducted a two-stage study, first measuring 405 miRNAs in a pilot study of six DEE-exposed workers exposed and six controls. In the second stage, 44 selected miRNAs were measured using the Fireplex circulating miRNA assay that profiles miRNAs directly from biofluids of 45 workers exposed to a range of DEE (Elemental Carbon (EC), median, range: 47.7, 6.1-79.7 μg/m³ ) and 46 controls. The relationship between exposure to DEE and EC with miRNA levels was analyzed using linear regression adjusted for potential confounders. Serum levels of four miRNAs were significantly lower (miR-191-5p, miR-93-5p, miR-423-3p, miR-122-5p) and one miRNA was significantly higher (miR-92a-3p) in DEE exposed workers compared to controls. Of these miRNAs, miR-191-5p (p_trend  = .001, FDR = 0.04) and miR-93-5p (p_trend  = .009, FDR = 0.18) showed evidence of an inverse exposure-response with increasing EC levels. Our findings suggest that occupational exposure to DEE may affect circulating miRNAs implicated in biological processes related to carcinogenesis, including immune function.

Association between diesel exhaust exposure and mitochondrial DNA methylation

BACKGROUND

Diesel exhaust is an established human carcinogen, however the mechanisms by which it leads to cancer development are not fully understood. Mitochondrial dysfunction is an established contributor to carcinogenesis. Recent studies have improved our understanding of the role played by epigenetic modifications in the mitochondrial genome on tumorigenesis. In this study, we aim to evaluate the association between diesel engine exhaust (DEE) exposure with mitochondrial DNA (mtDNA) methylation levels in workers exposed to DEE.

METHODS

The study population consisted of 53 male workers employed at a diesel engine manufacturing facility in Northern China who were routinely exposed to diesel exhaust in their occupational setting, as well as 55 unexposed male control workers from other unrelated factories in the same geographic area. Exposure to DEE, elemental carbon, organic carbon, and particulate matter (PM2.5) were assessed. mtDNA methylation for CpG sites (CpGs) from seven mitochondrial genes (D-Loop, MT-RNR1, MT-CO2, MT-CO3, MT-ATP6, MT-ATP8, MT-ND5) was measured in blood samples. Linear regression models were used to estimate the associations between DEE, elemental carbon, organic carbon and PM2.5 exposures with mtDNA methylation levels, adjusting for potential confounders.

RESULTS

DEE exposure was associated with decreased MT-ATP6 (difference= -35.6%, p-value= 0.019) and MT-ATP8 methylation (difference= -30%, p-value= 0.029) compared to unexposed controls. Exposures to elemental carbon, organic carbon, and PM2.5 were also significantly and inversely associated with methylation in MT-ATP6 and MT-ATP8 genes (all p-values < 0.05).

CONCLUSIONS

Our findings suggest that DEE exposure perturbs mtDNA methylation, which may be of importance for tumorigenesis.

Exposure to diesel engine exhaust and alterations to the Cys34/Lys525 adductome of human serum albumin

We investigated whether exposure to carcinogenic diesel engine exhaust (DEE) was associated with altered adduct levels in human serum albumin (HSA) residues. Nano-liquid chromatography-high resolution mass spectrometry (nLC-HRMS) was used to measure adducts of Cys34 and Lys525 residues in plasma samples from 54 diesel engine factory workers and 55 unexposed controls. An untargeted adductomics and bioinformatics pipeline was used to find signatures of Cys34/Lys525 adductome modifications. To identify adducts that were altered between DEE-exposed and unexposed participants, we used an ensemble feature selection approach that ranks and combines findings from linear regression and penalized logistic regression, then aggregates the important findings with those determined by random forest. We detected 40 Cys34 and 9 Lys525 adducts. Among these findings, we found evidence that 6 Cys34 adducts were altered between DEE-exposed and unexposed participants (i.e., 841.75, 851.76, 856.10, 860.77, 870.43, and 913.45). These adducts were biologically related to antioxidant activity.

Proteomic analysis of serum in workers exposed to diesel engine exhaust

Diesel engine exhaust (DEE) is classified as a Group 1 human carcinogen. Using a targeted proteomics approach, we aimed to identify proteins associated with DEE and characterize these markers to understand the mechanisms of DEE-induced carcinogenicity. In this cross-sectional molecular epidemiology study, we measured elemental carbon (EC) using a personal air monitor and quantified 1317 targeted proteins in the serum using the SOMAScan assay (SOMALogic) among 19 diesel exposed factory workers and 19 unexposed controls. We used linear regressions to identify proteins associated with DEE and examined their exposure-response relationship across levels of EC using linear trend tests. We further examined pathway enrichment of DEE-related proteins using MetaCore. Occupational exposure to DEE was associated with altered levels of 22 serum proteins (permutation p < .01). Of these, 13 proteins (CXCL11, HAPLN1, FLT4, CD40LG, PES1, IGHE.IGK..IGL, TNFSF9, PGD, NAGK, CCL25, CCL4L1, PDXK, and PLA2G1B) showed an exposure-response relationship with EC (p trend < .01), with serum levels of all but PLA2G1B declining with increasing air levels of EC. For instance, C-X-C Motif Chemokine Ligand 11 (CXCL11) showed the most significant association with DEE (β = -0.25; permutation p = .00004), where mean serum levels were 4121.1, 2356.7, and 2298.8 relative fluorescent units among the unexposed, lower exposed (median, range : 56.9, 40.2-62.1 μg/m³ EC), and higher exposed (median, range of EC: 72.9, 66.9-107.7 μg/m³ EC) groups, respectively (p trend = .0005). Pathway analysis suggested that these proteins are enriched in pathways related to inflammation and immune regulation. Our study suggests that DEE exposure is associated with altered serum proteins, which play a role in inflammation and immune regulation.

Abstract 856: Proteomic analysis of serum in workers exposed to diesel engine exhaust

Background: Diesel engine exhaust (DEE) is classified as a Group 1 human carcinogen by the International Agency for Research on Cancer because of its carcinogenicity to the lung. However, the underlying molecular mechanisms of DEE carcinogenicity are not well understood.

Methods: We previously conducted a cross-sectional molecular epidemiology study of diesel engine factory workers exposed to a wide range of DEE and unexposed comparable controls. Here, we carried out a pilot study of a representative subgroup of 19 exposed workers (total n = 54) and 19 unexposed controls (total n = 55). We measured serum level of 1238 targeted proteins using the SOMAScan assay (SOMALogic, Boulder, CA), which measures protein involved in a wide range of biological processes. We used linear regression to identify proteins associated with DEE (permutation p-value &lt;0.01), and examined their exposure-response relationship using a linear trend test across categories of elemental carbon (EC): unexposed (n = 19), lower exposed (median, range: 56.9, 40.2-62.1 µg/m3, n = 9), and higher exposed (median, range: 72.9, 66.9 - 107.7 µg/m3, n = 10), adjusted for age, smoking status, and body mass index. We further assessed correlations of DEE-related proteins with gene expression signature in the nasal epithelium (measured by Affymetrix microarrays) using Pearson's correlation, and examined their pathway enrichment using MetaCore.

Results: Occupational exposure to DEE was significantly associated with altered levels of 22 serum proteins. Of these, 13 proteins (CXCL11, HAPLN1, FLT4, CD40LG, PES1, IGHE.IGK..IGL, TNFSF9, PGD, NAGK, CCL25, CCL4L1, PDXK, and PLA2G1B) showed a significant exposure-response relationship with EC (p-trend &lt;0.01), with serum levels of all but PLA2G1B declining with increasing air levels of EC. For instance, CXCL11 showed the most significant association with DEE (β = -0.25; permutation p-value = 0.00004), where the median serum level of CXCL11 was 35.0 relative fluorescent unit (RFU) among the unexposed compared to 29.7 RFU among the lower exposed and 27.8 RFU among the higher exposed group (p-trend = 0.0005). Furthermore, four DEE-related proteins (CXCL11, PPY, CCL25, and SHH) also showed moderate to strong negative correlations (r = -0.52 to -0.72, all permutation p-values &lt;0.01) with the first principal component of a 225 DEE gene expression signature that we previously reported from nasal epithelial cells. Pathway enrichment analysis suggested that these proteins play a role in immunoregulatory and inflammatory processes, including Th17 cell migration; Th1, Th2, and endothelial cell differentiation; and differentiation and clonal expansion of CD8+ T cells (all FDR &lt;0.05).

Conclusion: Results from our pilot study suggest that DEE exposure is associated with alteration of multiple proteins in the serum, which play a role in inflammation and immune regulation. Analysis of a larger sample size will be needed to confirm our findings.

Citation Format: Mohammad L. Rahman, Yufei Dai, Roel Vermeulen, Wei Hu, Bryan Bassig, Eduard Drizik, Sean Corbett, Dianzhi Ren, Huawei Duan, Yong Niu, Jun Xu, Wei Fu, Kees Meliefste, Baosen Zhou, Xiaohui Zhang, Jufang Yang, Hanqiao Liu, Meng Ye, Gang Liu, Xiaowei Jia, Tao Meng, Ping Bin, Avrum Spira, Marc E. Lenburg, Debra Silverman, Nathaniel Rothman, Yuxin Zheng, Qing Lan. Proteomic analysis of serum in workers exposed to diesel engine exhaust [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 856.

Elevated Alu retroelement copy number among workers exposed to diesel engine exhaust

BACKGROUND

Millions of workers worldwide are exposed to diesel engine exhaust (DEE), a known genotoxic carcinogen. Alu retroelements are repetitive DNA sequences that can multiply and compromise genomic stability. There is some evidence linking altered Alu repeats to cancer and elevated mortality risks. However, whether Alu repeats are influenced by environmental pollutants is unexplored. In an occupational setting with high DEE exposure levels, we investigated associations with Alu repeat copy number.

METHODS

A cross-sectional study of 54 male DEE-exposed workers from an engine testing facility and a comparison group of 55 male unexposed controls was conducted in China. Personal air samples were assessed for elemental carbon, a DEE surrogate, using NIOSH Method 5040. Quantitative PCR (qPCR) was used to measure Alu repeat copy number relative to albumin (Alb) single-gene copy number in leucocyte DNA. The unitless Alu/Alb ratio reflects the average quantity of Alu repeats per cell. Linear regression models adjusted for age and smoking status were used to estimate relations between DEE-exposed workers versus unexposed controls, DEE tertiles (6.1-39.0, 39.1-54.5 and 54.6-107.7 µg/m³) and Alu/Alb ratio.

RESULTS

DEE-exposed workers had a higher average Alu/Alb ratio than the unexposed controls (p=0.03). Further, we found a positive exposure-response relationship (p=0.02). The Alu/Alb ratio was highest among workers exposed to the top tertile of DEE versus the unexposed controls (1.12±0.08 SD vs 1.06±0.07 SD, p=0.01).

CONCLUSION

Our findings suggest that DEE exposure may contribute to genomic instability. Further investigations of environmental pollutants, Alu copy number and carcinogenesis are warranted.

Assessment of Benchmark Dose in BEAS-2B Cells by Evaluating the Cell Relative Viability with Particulates in Motorcycle Exhaust via the Air-liquid Interface Exposure

OBJECTIVE

This study aimed to use an air-liquid interface (ALI) exposure system to simulate the inhalation exposure of motorcycle exhaust particulates (MEPs) and then investigate the benchmark dose (BMD) of MEPs by evaluating cell relative viability (CRV) in lung epithelial BEAS-2B cells.

METHODS

The MEPs dose was characterized by measuring the number concentration (NC), surface area concentration (SAC), and mass concentration (MC). BEAS-2B cells were exposed to MEPs at different concentrations via ALI and CRV was determined using Cell Counting Kit (CCK-8) assay. BMD software was applied to calculate BMD and the lower limit of benchmark dose (BMDL) according to Akaike Information Coefficient (AIC), with P-value based on Hill, Linear, Polynomial, and Power model.

RESULTS

Our results reveal that BMD of NC and SAC were estimated by the best-fitting Hill model, while MC was estimated by Polynomial model. The BMDL for CRV following ALI exposure to MEPs were as follows: 364.2#/cm ³ for NC; 0.662 × 10 ⁷ nm ²/cm ³ for SAC; and 0.278 μg/m ³ for MC.

CONCLUSION

These results indicate that MEPs exposure via ALI system induces a dose-dependent decrease of CRV and provides the potential exposure threshold of MEPs in a lung cell model.

[Analysis of the relationship between the changes of lung function and serum proinflammatory cytokines in workers occupationally exposed to toluene diisocyanate]

Objective: To analyze the correlation between the changes of lung function and serum proinflammatory cytokines in workers occupationally exposed to toluene diisocyanate (TDI), and to explore the evaluation index of respiratory toxicity of TDI. Methods: In October 2014, 61 male workers engaged in TDI synthesis process, purification process, packaging process and the above production process in a TDI factory in western China were selected as TDI exposure group; 62 male enterprise managers who were not exposed to TDI and other known allergenic chemicals were selected as control group, which were matched at the age of workers in exposure group. The questionnaire survey obtained information such as gender, length of service, age, occupational history, exposed length of service and so on. The lung function indexes [forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC] and serum levels of interleukin (IL)-1 β, IL-6, IL-8, tumor necrosis factor (TNF)-α, macrophage inflammatory factor-1 β, monocyte chemoattractant factor-1 and vascular endothelial growth factor were measured. The urine was collected after the weekend shift, and the concentration of (TDA), the metabolite of TDI, was determined as the index of internal exposure. Spearman rank correlation was used to analyze the correlation between cytokines and lung function indexes, and multivariate linear regression was used to analyze the changes of lung function indexes and cytokines with TDI exposure concentration and time. Results: The median age (P₅-P₉₅) of the exposed group and the control group was 36.5 (24.0-51.0) and 38.0 (24.0-50.0) years, respectively. In the exposed group, the median length of service (P₅-P₉₅) was 6.94 (0.97-26.33) years, and the median concentration of TDA in urine was 15.56 (2.28-112.16) ng/ml. The three indexes of lung function, FVC, FEV1, FEV1/FVC and the levels of serum IL-8 and TNF-α were significantly lower than those in the control group (P<0.01). With the increase of exposure concentration and exposure time, the level of serum TNF-α, FVC and FEV1 decreased, and showed a good dose-effect and time-effect relationship (all P_trend values< 0.05). Serum IL-8 and TNF-α were positively correlated with FVC, FEV1 and FEV1/FVC (all P values<0.01). Conclusion: The levels of serum inflammatory factors IL-8 and TNF-α in worker exposed to TDI are related to lung function indexes, which can be used as early evaluation indexes of respiratory toxicity induced by TDI.

Transcriptomic changes in the nasal epithelium associated with diesel engine exhaust exposure

BACKGROUND

Diesel engine exhaust (DEE) exposure causes lung cancer, but the molecular mechanisms by which this occurs are not well understood.

OBJECTIVES

To assess transcriptomic alterations in nasal epithelium of DEE-exposed factory workers to better understand the cellular and molecular effects of DEE.

METHODS

Nasal epithelial brushings were obtained from 41 diesel engine factory workers exposed to relatively high levels of DEE (17.2-105.4 μg/m3), and 38 unexposed workers from factories without DEE exposure. mRNA was profiled for gene expression using Affymetrix microarrays. Linear modeling was used to identify differentially expressed genes associated with DEE exposure and interaction effects with current smoking status. Pathway enrichment among differentially expressed genes was assessed using EnrichR. Gene Set Enrichment Analysis (GSEA) was used to compare gene expression patterns between datasets.

RESULTS

225 genes had expression associated with DEE exposure after adjusting for smoking status (FDR q < 0.25) and were enriched for genes in pathways related to oxidative stress response, cell cycle pathways such as MAPK/ERK, protein modification, and transmembrane transport. Genes up-regulated in DEE-exposed individuals were enriched among the genes most up-regulated by cigarette smoking in a previously reported bronchial airway smoking dataset. We also found that the DEE signature was enriched among the genes most altered in two previous studies of the effects of acute DEE on PBMC gene expression. An exposure-response relationship was demonstrated between air levels of elemental carbon and the first principal component of the DEE signature.

CONCLUSIONS

A gene expression signature was identified for workers occupationally exposed to DEE that was altered in an exposure-dependent manner and had some overlap with the effects of smoking and the effects of acute DEE exposure. This is the first study of gene expression in nasal epithelial cells of workers heavily exposed to DEE and provides new insights into the molecular alterations that occur with DEE exposure.

Utility evaluation of HLA-B*13:01 screening in preventing trichloroethylene-induced hypersensitivity syndrome in a prospective cohort study

OBJECTIVES

Trichloroethylene (TCE) -induced hypersensitivity syndrome (TIHS) is a potentially life-threatening disease. Several genetic susceptibility biomarkers have been found to be associated with TIHS, and this systematic prospective study has been conducted to evaluate the utility of these genetic susceptibility biomarkers in preventing the disease.

METHODS

The newly hired TCE-exposed workers were recruited from March 2009 to October 2010. HLA-B*13:01 genotyping and 3-month follow-up procedure were conducted. All workers were monitored for adverse reaction by telephone interview every week. The workers with early symptoms of TIHS were asked to go to the hospital immediately for further examination, diagnosis and treatment. The medical expense record data of patients with TIHS were collected for cost-effectiveness analysis in 2018.

RESULTS

Among 1651 workers, 158 (9.57%) were found to carry the HLA-B*13:01 allele and 16 (0.97%) were diagnosed with TIHS. HLA-B*13:01 allele was significantly associated with an increased TIHS risk (relative risk=28.4, 95% CI 9.2 to 86.8). As a risk predictor of TIHS, HLA-B*13:01 testing had a sensitivity of 75%, a specificity of 91.1% and an area under curve of 0.83 (95% CI 0.705 to 0.955), the positive and negative predictive values were 7.6% and 99.7%, respectively. The incidence of TIHS was significantly decreased in HLA-B*13:01 non-carriers (0.27%) compared with all workers (0.97%, p=0.014). Cost-effectiveness analysis showed that HLA-B*13:01 screening could produce an economic saving of $4604 per TIHS avoided.

CONCLUSIONS

Prospective HLA-B*13:01 screening may significantly reduce the incidence of TIHS and could be a cost effective option for preventing the disease in TCE-exposed workers.

Abstract 597: Occupational exposure to diesel engine exhaust and alternations in serum microRNAs

Diesel engine exhaust (DEE) is a known lung carcinogen and may be associated with other tumors, however, the mechanisms of action by which DEE causes cancer is not well understood. MicroRNAs (miRNAs), which are small non-coding RNA molecules that play a role in post-transcriptional regulation of gene expression, are altered in multiple tumors and have been observed to be differentially expressed in a variety of biospecimen types in smokers as well as in relation to short-term air pollution exposure. To evaluate whether serum levels of miRNAs are altered in healthy workers occupationally exposed to DEE, we analyzed samples collected in a cross-sectional molecular epidemiology study of diesel engine truck testing facility workers and comparable unexposed controls in China. A panel of 44 miRNAs were measured in 46 workers exposed to relatively high air levels of DEE and 45 controls using the Fireplex circulating miRNA assay (Abcam, Inc.), which profiles miRNAs directly from biofluids. The exposure-response relationship between categorical EC levels and each miRNA was analyzed by linear regression adjusted for age, body mass index, smoking status, current alcohol use and recent infection. We identified two miRNAs that showed a monotonic inverse exposure-response association with DEE: miR-191-5p and miR-93-5p. Levels of miR-191-5p in arbitrary units (A.U.) of fluorescence were 400.7, 333.0, 322.6, and 260.0 in controls and across increasing tertiles of EC, respectively (p for trend = 0.001, FDR = 0.05). Levels of miR-93-5p were 747.1, 713.7, 720.5, and 625.4 A.U. in controls and increasing tertiles of EC, respectively (p for trend = 0.008, FDR = 0.18). Both miRNAs have been reported to influence several biological processes important in carcinogenesis. Our results suggest that occupational exposure to DEE may affect circulating miRNAs in healthy workers.

Citation Format: Wei Hu, Bryan A. Bassig, Yufei Dai, Dianzhi Ren, Huawei Duan, Yong Niu, Jun Xu, Wei Fu, Kees Meliefste, Baosen Zhou, Jufang Yang, Meng Ye, Xiaowei Jia, Tao Meng, Ping Bin, Jason YY Wong, Dean H. Hosgood, Nathaniel Rothman, Roel C. Vermeulen, Debra T. Silverman, Yuxin Zheng, Qing Lan. Occupational exposure to diesel engine exhaust and alternations in serum microRNAs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 597.

Exposure characterization and estimation of benchmark dose for cancer biomarkers in an occupational cohort of diesel engine testers

Exposure to diesel engine exhaust (DEE) was associated with various adverse health effects including lung cancer. Particle size distribution and profiles of organic compounds in both particle and gas phases of DEE that could provide valuable insights into related health effects were measured in a diesel engine testing workshop. Concentrations of urinary 6 mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 137 DEE-exposed workers and 127 non-DEE-exposed workers were determined. Benchmark dose method was applied to estimate lower limit of benchmark dose (BMDL) of urinary OH-PAHs most specific to DEE exposure for previously reported cancer biomarkers. We found that 84.3% of diesel exhaust particles were ultrafine particles. Indeno[123-cd]pyrene and phenanthrene were the most abundant carcinogenic and noncarcinogenic PAHs in the particle phase of DEE, respectively. Principal component analysis demonstrated that urinary hydroxyphenanthrene (OHPhe) had highest loading value on principal component (PC) representative of DEE exposure and lowest loading value on PC representative of smoking status. BMDLs of urinary OHPhe from best-fitting models for cancer biomarkers including micronucleus and 1,N⁶-ethenodeoxyadenosine were 1.08 μg/g creatinine and 2.82 μg/g creatinine, respectively. These results provided basis for understanding DEE exposure induced health effects and potential threshold for regulating DEE levels in an occupational setting.

Occupational exposure to diesel engine exhaust and serum cytokine levels

The International Agency for Research on Cancer has classified diesel engine exhaust (DEE) as a human lung carcinogen. Given that inflammation is suspected to be an important underlying mechanism of lung carcinogenesis, we evaluated the relationship between DEE exposure and the inflammatory response using data from a cross-sectional molecular epidemiology study of 41 diesel engine testing workers and 46 unexposed controls. Repeated personal exposure measurements of PM_2.5 and other DEE constituents were taken for the diesel engine testing workers before blood collection. Serum levels of six inflammatory biomarkers including interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1β, and monocyte chemotactic protein (MCP)-1 were analyzed in all subjects. Compared to unexposed controls, concentrations of MIP-1β were significantly reduced by ∼37% in DEE exposed workers (P < 0.001) and showed a strong decreasing trend with increasing PM_2.5 concentrations in all subjects (P_trend  < 0.001) as well as in exposed subjects only (P_trend  = 0.001). Levels of IL-8 and MIP-1β were significantly lower in workers in the highest exposure tertile of PM_2.5 (>397 µg/m³ ) compared to unexposed controls. Further, significant inverse exposure-response relationships for IL-8 and MCP-1 were also found in relation to increasing PM_2.5 levels among the DEE exposed workers. Given that IL-8, MIP-1β, and MCP-1 are chemokines that play important roles in recruitment of immunocompetent cells for immune defense and tumor cell clearance, the observed lower levels of these markers with increasing PM_2.5 exposure may provide insight into the mechanism by which DEE promotes lung cancer. Environ. Mol. Mutagen. 59:144-150, 2018. © 2017 Wiley Periodicals, Inc.

[Association of etheno-DNA adduct and DNA methylation level among workers exposed to diesel engine exhaust]

Objective: To investigate the association between etheno-DNA adduct and the promoter of DNA methylation levels of cyclin dependent kinase inhibitor 2A (P16), Ras association domain family 1 (RASSF1A) and O-6-methylguanine-DNA methyltransferase (MGMT) in workers with occupational exposure to diesel engine exhaust (DEE). Methods: We recruited 124 diesel engine testing workers as DEE exposure group and 112 water pump operator in the same area as control group in Henan province in 2012 using cluster sampling. The demographic data were obtained by questionnaire survey; urine after work and venous blood samples were collected from each subject. The urinary etheno-DNA adducts were detected using UPLC-MS/MS, including 1,N6-etheno-2'-deoxyadenosine (εdA) and 3,N4-etheno-2'-deoxycytidine(εdC). The DNA methylation levels of P16, RASSF1A, and MGMT were evaluated using bisulfite-pyrosequencing assay. The percentage of methylation was expressed as the 5-methylcytosine (5mC) over the sum of cytosines (%5mC). Spearman correlation and multiple linear regression were applied to analyze the association between etheno-DNA adducts and DNA methylation of P16, RASSF1A, and MGMT. Results: The median (P(25)-P(75)) of urinary εdA level was 230.00 (98.04-470.91) pmol/g creatinine in DEE exposure group, and 102.10 (49.95-194.48) creatinine in control group. The level of εdA was higher in DEE exposure group than control group (P<0.001). DNA methylation levels of P16, RASSF1A and MGMT were 2.04±0.41, 2.19 (1.94-2.51), 2.22 (1.94-2.46)%5mC in exposure group, and 2.19±0.40, 2.41 (2.11-2.67), 2.44 (2.15-2.91)%5mC in control group. DNA methylation levels were lower in exposure group (P values were 0.005, 0.002 and 0.001, respectively). Spearman correlation analysis showed that DNA methylation levels of P16, RASSF1A, and MGMT were negative associated with urinary εdA level (r values were -0.155, -0.137, and -0.198, respectively, P<0.05). No significant correlation was observed between the εdC level and any measured DNA methylation levels (P>0.05) . Multiple linear regression confirmed the negative correlation between εdA and DNA methylation levels of P16, RASSF1A, and MGMT in non-smoking group (β (95%CI) was -0.068 (-0.132--0.003), -0.082 (-0.159--0.004) and -0.048 (-0.090--0.007), P values were 0.039, 0.039 and 0.024, respectively). Moreover, εdC was negative associated with DNA methylation level of MGMT in non-smoking group (β (95%CI) was -0.094 (-0.179--0.008), P=0.032). Conclusion: DEE exposure could induce the increased of εdA and decreased of DNA methylation levels of P16, RASSF1A and MGMT.

Occupational exposure to diesel engine exhaust and alterations in immune/inflammatory markers: a cross-sectional molecular epidemiology study in China

The relationship between diesel engine exhaust (DEE), a known lung carcinogen, and immune/inflammatory markers that have been prospectively associated with lung cancer risk is not well understood. To provide insight into these associations, we conducted a cross-sectional molecular epidemiology study of 54 males highly occupationally exposed to DEE and 55 unexposed male controls from representative workplaces in China. We measured plasma levels of 64 immune/inflammatory markers in all subjects using Luminex bead-based assays, and compared our findings to those from a nested case-control study of these markers and lung cancer risk, which had been conducted among never-smoking women in Shanghai using the same multiplex panels. Levels of nine markers that were associated with lung cancer risk in the Shanghai study were altered in DEE-exposed workers in the same direction as the lung cancer associations. Among these, associations with the levels of CRP (β= -0.53; P = 0.01) and CCL15/MIP-1D (β = 0.20; P = 0.02) were observed in workers exposed to DEE and with increasing elemental carbon exposure levels (Ptrends <0.05) in multivariable linear regression models. Levels of a third marker positively associated with an increased lung cancer risk, CCL2/MCP-1, were higher among DEE-exposed workers compared with controls in never and former smokers, but not in current smokers (Pinteraction = 0.01). The immunological differences in these markers in DEE-exposed workers are consistent with associations observed for lung cancer risk in a prospective study of Chinese women and may provide some insight into the mechanistic processes by which DEE causes lung cancer.

[Toxicity of vehicle exhaust on BEAS-2B cells in vitro by air-liquid interface]

OBJECTIVE

To evaluate the toxic effect of vehicle exhaust( VE) on lung epithelial cells by air-liquid interface( ALI) method in vitro, and analyze the different toxicity of VE after being treated with 0. 2 μm filter.

METHODS

VE were collected using20 liter Tedlar bags and their particulate matter( PM) number, surface and mass concentration were measured by particle size spectrometer for the interference of 0. 2 μm filter or non-filter. Four groups were included, which divided into blank control group, clean air group, filtered VE exposure group, non-filtered VE exposure group. The blank control group did not do any treatment; the clean air group was an artificial gas containing21% O_2 and 79% N_2; the filtered VE group( marked as f VE) was filtered using a 0. 2μm particle filter for VE. The VE group was used VE directly collected by air bag and marked as non-f VE. Except the blank control group, BEAS-2B cells were treated with clean air or VE by ALI method at a flow rate of 25 mL/min, 37 ℃ for 60 min in vitro. Cell relative viability was evaluated by CCK-8 assay. The reactive oxygen species( ROS)generation was determined via flow cytometry with 2', 7'-dichloro-dihydro-fluorescein diacetate( DCFH-DA) probe. Apoptosis and necrosis rate were measured using the commercial kit of Annexin V-FITC/PI by flow cytometry.

RESULTS

In the non-f VE group, the PM of number, surface and mass concentration for 0. 5-10 μm diameters were 0. 24×10~3N/cm~3, 0. 29 ×10~3μm~2/cm~3 and 0. 19 μg/m~3, respectively, and for the PM of 10-500 nm diameters, they were 56 ×10~3N/cm~3、34. 53 ×10~8nm~2/cm~3 and 95ng/m~3, respectively. The PM of 0. 5-10 μm diameters in f VE group, their number, surface and mass concentration were less than 1 N/cm~3, 1 μm~2/cm~3 0. 001 μg/m~3, respectively. After filtration, the number, surface and mass concentration of PM in 10-500 nm diameters reduced by 89. 79%, 93. 57% and 90. 55%, respectively, as compared with non-f VE. In the clean air group, the cell relative viability, ROS generation, early apoptosis rate and late apoptosis and necrosis rate were( 90. 15 ± 4. 25) %, ( 1. 92 ± 0. 34)×10~5, ( 1. 09 ± 0. 48) % and( 8. 93 ± 3. 31) %, respectively. Compared with the clean air group, the cell relative viability, the ROS generation and the late apoptosis and necrosis rate of the two VE exposure groups were significantly different( all P < 0. 05). The cell relative viability of f VE exposure group were significantly higher than that in the non-f VE exposure group( t = 6. 331, P < 0. 001), and had no significant difference about the ROS generation[f VE ∶ non-VE =( 2. 94 ± 0. 21) ×10~5∶( 3. 32 ± 0. 49) ×10~5, t =-1. 252, P = 0. 279], early apoptosis rate [f VE∶ non-VE =( 1. 09 ± 0. 30) % ∶( 0. 99 ±0. 10) %, t = 0. 708, P = 0. 497] and late apoptosis and necrosis rate [f VE ∶ non-VE =( 21. 75 ± 10. 37) % ∶( 15. 32 ± 2. 74) %, t = 1. 347, P = 0. 242] between f VE and nonf VE exposure group( all P > 0. 05).

CONCLUSION

Increased toxicity of human lung cells( BEAS-2B) in vitro were observed by ALI method at a flow rate of 25 mL/min, 37 ℃ for60 min. After using a 0. 2 μm filter, the toxicity was obviously decreased.

The use of a 0.20 μm particulate matter filter decreases cytotoxicity in lung epithelial cells following air-liquid interface exposure to motorcycle exhaust

This study was designed to investigate whether the use of a 0.20 μm particulate matter (PM) filter reduced the cytotoxicity induced by motorcycle exhaust (ME), a mixture of gases and particles, in lung epithelial cells cultured in air-liquid interface (ALI) inserts. The concentrations of PM, carbon monoxide, carbon dioxide, total hydrocarbons (THC), total volatile organic compounds, and nitrogen oxides in both filtered ME (fME) by a 0.20 μm filter and non-filtered ME (non-fME) were measured. Lung epithelial cells were exposed to clean air, fME, or non-fME in the ALI chamber. Cell relative viabilities (CRV) and the reactive oxygen species (ROS) generation were determined. Our results revealed that PM_2.5 was the main compound of PM in ME. After filtration, PM and THC levels were significantly reduced, as compared with non-fME. When compared with the clean air exposed group, the CRV in both fME and non-fME-exposed group was significantly reduced (p < 0.001), while their ROS generation were markedly increased (p < 0.001). When compared with non-fME-exposed group, the CRV and ROS generation were significantly improved following fME exposure (p < 0.05). As a result, of PM and THC concentrations were decreased approximately 90% and 22.71%, respectively, the CRV was improved from 40.4% (non-fME) to 55.7% (fME), and the increased ROS generation by non-fME was decreased about 51.6%. When BEAS-2B cells were exposed to fME, a time-dependent reduction in CRV was observed. In conclusion, our findings suggest that ME-exposure in the ALI system induces cytotoxicity and oxidative stress responses. The addition of a 0.20 μm PM filter significantly modifies the particulate composition in PM and the concentration of THC, and shows protective effects by improving the survival of exposed lung epithelial cells and reducing the ROS generation. Therefore, emission factors such as different size of PM and THC from motorcycles may play a role in ME-induced toxicity.

Effects of occupational exposure to carbon black on peripheral white blood cell counts and lymphocyte subsets

The International Agency for Research on Cancer has classified carbon black (CB) as a possible (Group 2B) human carcinogen. Given that most CB manufacturing processes result in the emission of various types of chemicals, it is uncertain if the adverse health effects that have been observed in CB-exposed workers are related to CB specifically or are due to other exposures. To address this issue, we conducted a cross-sectional molecular epidemiology study in China of 106 male factory workers who were occupationally exposed to pure CB and 112 unexposed male workers frequency-matched by age and smoking status from the same geographic region. Repeated personal exposure measurements were taken in workers before biological sample collection. Peripheral blood from all workers was used for the complete blood cell count and lymphocyte subsets analysis. Compared to unexposed workers, eosinophil counts in workers exposed to CB were increased by 30.8% (P = 0.07) after adjusting for potential confounders. When stratified by smoking status, statistically significant differences in eosinophils between CB exposed and unexposed workers were only present among never smokers (P = 0.040). Smoking is associated with alterations in various cell counts; however, no significant interaction between CB exposure and smoking status for any cell counts was observed. Given that inflammation, characterized in part by elevated eosinophils in peripheral blood, may be associated with increased cancer risk, our findings provide new biologic insights into the potential relationship between CB exposure and lung carcinogenesis. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.

Increased levels of urinary biomarkers of lipid peroxidation products among workers occupationally exposed to diesel engine exhaust

Diesel engine exhaust (DEE) was found to induce lipid peroxidation (LPO) in animal exposure studies. LPO is a class of oxidative stress and can be reflected by detecting the levels of its production, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), and etheno-DNA adducts including 1,N(6)-etheno-2'-deoxyadenosine (ɛdA) and 3,N(4)-etheno-2'-deoxycytidine (ɛdC). However, the impact of DEE exposure on LPO has not been explored in humans. In this study, we evaluated urinary MDA, 4-HNE, ɛdA, and ɛdC levels as biomarkers of LPO among 108 workers with exclusive exposure to DEE and 109 non-DEE-exposed workers. Results showed that increased levels of urinary MDA and ɛdA were observed in subjects occupationally exposed to DEE before and after age, body mass index (BMI), smoking status, and alcohol use were adjusted (all p < 0.001). There was a statistically significant relationship between the internal exposure dose (urinary ΣOH-PAHs) and MDA, 4-HNE, and ɛdA (all p < 0.001). Furthermore, significant increased relations between urinary etheno-DNA adduct and MDA, 4-HNE were observed (all p < 0.05). The findings of this study suggested that the level of LPO products (MDA and ɛdA) was increased in DEE-exposed workers, and urinary MDA and ɛdA might be feasible biomarkers for DEE exposure. LPO induced DNA damage might be involved and further motivated the genomic instability could be one of the pathogeneses of cancer induced by DEE-exposure. However, additional investigations should be performed to understand these observations.

[Optimization of primary hepatocytes model and study on the cytotoxicity of styrene and styrene oxide]

OBJECTIVE

To establish a model in vitro for primary cultured mouse hepatocytes with high viability and function, and evaluate the acute toxicity of the primary hepatocytes exposed to the chemicals such as styrene and styrene oxide (SO).

METHODS

Based on the classical method, the two-step collagenase digestion method was optimized by reverse and intermittent perfusion, restriction of digestion time as well as purification of percoll liquid. Hepatocytes were isolated from BALB/C mouse by an improved isolated method and then cultured in monolayer and sandwich configuration. The primary cultured hepatocytes model was assessed by various indexes including cell morphology, cell viability, intracellular glycogen granules, as well as albumin (ALB), lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and blood urine nitrogen (BUN) levels in the supernatant. In addition, the primary cultured hepatocytes were treated with various concentrations from 0.2 to 25 micromol/L of styrene and styrene oxide during different time from 3 to 48 hours. The cytotoxicity induced by the two toxicants was assessed by CCK-8 and LDH assays.

RESULTS

On average, the isolation using this improved method resulted in the cell viability of (90.3 +/- 5.2) %, the cell purity of (95.3 +/- 4.2)% and the yield of (2.4 +/- 0.9) x 10(7) viable cells. More than 90% cells showed a typical morphological feature of hepatocytes in sandwich configuration within 7 days, and contained a large number of glycogen granules on the third day. The ALB secretion, ALT and LDH leakage and BUN synthesis as well as cell viability fluctuated during 8 days, and they stayed at stable levels between 3 to 7 days in sandwich configuration. But they fluctuated during 6 days in monolayer configuration. In comparison with the monolayer configuration, the levels of ALB and BUN were distinctly increased and the levels of LDH and ALT were significantly decreased in sandwich configuration. The levels of ALB [ (1.42 +/- 0.20) g/L ] and BUN [(1.97 +/- 0.22) mmol/L] as well as cell viability were the highest, while the levels of LDH [ (7.30 +/- 2.33) U/L] and ALT [ (6.51 +/- 1.86) U/L] were the lowest in sandwich configuration on the third day. The relative low cytotoxicity and high cell survival rate ( more than 90%) were shown in treated hepatocytes with styrene and styrene oxide within 6 hours by CCK-8 and LDH measurements, and there was no distinct difference in the determination of cytotoxicity between the two methods. With the prolonged exposure time, the cell survival rate was lower by CCK-8 assay (less than 85%) than the one by LDH assay. The relative obvious cytotoxicity and low cell survival rate (about 85%) by CCK-8 method were revealed in treated cells with 5 micromol/L of styrene and styrene oxide for 24 hours, but there was no significant difference between CCK-8 and LDH assays. With the increase of the concentrations, the cell survival rate was lower by CCK-8 assay (less than 80%) compared with LDH assay.

CONCLUSION

The improved two-step collagenase digestion method combination with sandwich culture method might maintain the morphology and function of primary cultured mouse hepatocytes for seven days. The cytotoxic effects of styrene and styrene oxide might be accurately evaluated by means of primary cultured hepatocyte model from 3 to 7 days. The chemicals might have major adverse effects on the functions of the organelles in hepatocytes such as mitochondria, but little influence to the cell membrane damage.

Long-term exposure to diesel engine exhaust affects cytokine expression among occupational population

Diesel engine exhaust (DEE) is a predominant contributor to urban air pollution. The International Agency for Research on Cancer classified DEE as a group I carcinogen. Inflammatory response is considered to be associated with various health outcomes including carcinogenesis. However, human data linking inflammation with long-term DEE exposure are still lacking. In this study, a total of 137 diesel engine testing workers with an average exposure of 8.2 years and 108 unexposed controls were enrolled. Peripheral blood samples were collected from all subjects, and the association of DEE exposure with inflammatory biomarkers was analyzed. Overall, DEE exposed workers had a significant increase in the C-reactive protein (CRP) and a significant decrease in cytokines including interleukin (IL)-1β, IL-6, IL-8, and macrophage inflammatory protein (MIP)-1β compared to controls after adjusting for age, BMI, smoking status, and alcohol use, and findings were highly consistent when stratified by smoking status. In addition, exposure time dependent patterns for IL-6 and CRP were also found (Ptrend = 0.006 and 0.026, respectively); however, the levels of IL-1β and MIP-1β were significantly lower in subjects with a DEE working time of less than 10 years compared with the controls and then recovered to control levels in workers exposed for >10 years. There were no significant differences in blood cell counts and major lymphocyte subsets between exposed workers and the controls. Our results provide epidemiological evidence for the relationship between DEE exposure and immunotoxicity considering the important roles of cytokines in immunological processes.

Increased levels of etheno-DNA adducts and genotoxicity biomarkers of long-term exposure to pure diesel engine exhaust

Etheno-DNA adducts are biomarkers for assessing oxidative stress. In this study, the aim was to detect the level of etheno-DNA adducts and explore the relationship between the etheno-DNA adducts and genotoxicity biomarkers of the diesel engine exhaust (DEE)-exposed workers. We recruited 86 diesel engine testing workers with long-term exposure to DEE and 99 non-DEE-exposed workers. The urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and etheno-DNA adducts (εdA and εdC) were detected by HPLC-MS/MS and UPLC-MS/MS, respectively. Genotoxicity biomarkers were also evaluated by comet assay and cytokinesis-block micronucleus assay. The results showed that urinary εdA was significantly higher in the DEE-exposed workers (p<0.001), exhibited 2.1-fold increase compared with the non-DEE-exposed workers. The levels of urinary OH-PAHs were positively correlated with the level of εdA among all the study subjects (p<0.001). Moreover, we found that the increasing level of εdA was significantly associated with the increased olive tail moment, percentage of tail DNA, or frequency of micronucleus in the study subjects (p<0.01). No significant association was observed between the εdC level and any measured genotoxicity biomarkers. In summary, εdA could serve as an indicator for DEE exposure in the human population.

Further considerations in terms of the permanent impairment of the of chewing organ

Nowadays, the drawbacks to utilizing criminal law with regards to a traumatic event, whether accidental or iatrogenic, involving the dental apparatus are still prevailing. A lesion affecting the stomatognathic apparatus can in fact integrate the offense of grievous bodily harm under Art.583 of the Italian Criminal Code (cc) as "permanent weakening of the organ" or the functions to which is appointed, i.e. the masticatory function, but also to the indwelling voice, appearance and taste. Repeatedly, jurisprudence, in the past and more recently, has set an opinion on the issue and, currently, it is possible to indicate some recognized cornerstones as deep-seated on the matter. It is a well-known fact that the organ of mastication does not represent a defined anatomical organ but, instead, it is an anatomical and functional entity consisting of a complex of different structures and not just from the dental apparatus. Moreover, any functional anatomic alteration of any single entity can have a certain weight on the other components and, therefore, on the whole organ in its entirety. Medical-legal doctrine, already in the past, supported the need for a tangible assessment of the impairment, determining whether and how much the loss of even one anatomical element could have a negative impact on the operational equilibrium of the entire stomatognathic system, whilst verifying the actual subsistence of a weakening. The loss of a dental element can take on a different meaning when such event occurs on a system already functionally deficient. In such instances, one should consider whether any pre-existing condition compromise the system, and to what extent, so that the trauma has considerable bearing on the remaining masticatory function. If the apparatus is in a position to perform even in part its function, the blunt force trauma is likely to set the aggravating circumstance.

Occupational exposure to diesel engine exhaust and alterations in lymphocyte subsets

BACKGROUND

The International Agency for Research on Cancer recently classified diesel engine exhaust (DEE) as a Group I carcinogen based largely on its association with lung cancer. However, the exposure-response relationship is still a subject of debate and the underlying mechanism by which DEE causes lung cancer in humans is not well understood.

METHODS

We conducted a cross-sectional molecular epidemiology study in a diesel engine truck testing facility of 54 workers exposed to a wide range of DEE (ie, elemental carbon air levels, median range: 49.7, 6.1-107.7 µg/m(3)) and 55 unexposed comparable controls.

RESULTS

The total lymphocyte count (p=0.00044) and three of the four major lymphocyte subsets (ie, CD4+ T cells (p=0.00019), CD8+ T cells (p=0.0058) and B cells (p=0.017)) were higher in exposed versus control workers and findings were highly consistent when stratified by smoking status. In addition, there was evidence of an exposure-response relationship between elemental carbon and these end points (ptrends<0.05), and CD4+ T cell levels were significantly higher in the lowest tertile of DEE exposed workers compared to controls (p=0.012).

CONCLUSIONS

Our results suggest that DEE exposure is associated with higher levels of cells that play a key role in the inflammatory process, which is increasingly being recognised as contributing to the aetiology of lung cancer.

IMPACT

This study provides new insights into the underlying mechanism of DEE carcinogenicity.

Reduced pulmonary function and increased pro-inflammatory cytokines in nanoscale carbon black-exposed workers

BACKGROUND

Although major concerns exist regarding the potential consequences of human exposures to nanoscale carbon black (CB) particles, limited human toxicological data is currently available. The purpose of this study was to evaluate if nanoscale CB particles could be responsible, at least partially, for the altered lung function and inflammation observed in CB workers exposed to nanoscale CB particles.

METHODS

Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Brunauer-Emmett-Teller were used to characterize CB. Eighty-one CB-exposed male workers and 104 non-exposed male workers were recruited. The pulmonary function test was performed and pro-inflammatory cytokines were evaluated. To further assess the deposition and pulmonary damage induced by CB nanoparticles, male BALB/c mice were exposed to CB for 6 hours per day for 7 or 14 days. The deposition of CB and the pathological changes of the lung tissue in mice were evaluated by paraffin sections and TEM. The cytokines levels in serum and lung tissue of mice were evaluated by ELISA and immunohistochemical staining (IHC).

RESULTS

SEM and TEM images showed that the CB particles were 30 to 50 nm in size. In the CB workplace, the concentration of CB was 14.90 mg/m³. Among these CB particles, 50.77% were less than 0.523 micrometer, and 99.55% were less than 2.5 micrometer in aerodynamic diameter. The reduction of lung function parameters including FEV1%, FEV/FVC, MMF%, and PEF% in CB workers was observed, and the IL-1β, IL-6, IL-8, MIP-1beta, and TNF- alpha had 2.86-, 6.85-, 1.49-, 3.35-, and 4.87-folds increase in serum of CB workers, respectively. In mice exposed to the aerosol CB, particles were deposited in the lung. The alveolar wall thickened and a large amount of inflammatory cells were observed in lung tissues after CB exposure. IL-6 and IL-8 levels were increased in both serum and lung homogenate.

CONCLUSIONS

The data strongly suggests that nanoscale CB particles could be responsible for the lung function reduction and pro-inflammatory cytokines secretion in CB workers. These results, therefore, provide the first evidence of a link between human exposure to CB and long-term pulmonary effects.

Peptide-binding motifs and characteristics for HLA -B*13:01 molecule

Trichloroethylene (TCE)-induced hypersensitivity dermatitis is one of the critical occupational diseases among workers in China. Our previous studies have identified a strong linkage between the disease and the HLA-B*13:01 allele. In this study, we searched for peptides bound to the HLA-B*13:01 molecule; 57 HLA-B*13:01-bound peptides in total were identified and 54 peptides were used to calculate frequency of amino acid residues to obtain binding motifs of HLA-B*13:01 molecule. The results showed P2, P3, and P9 were the primary binding anchor positions with the dominant anchor motifs of L, Q at P2, L at P9, D at P3. HLA-B*13:01-bound peptides were identified for the first time in our research, the results of which could contribute to the human leukocyte antigen (HLA)-binding peptides database.

Myelin protein zero and its antibody in serum as biomarkers of n-hexane-induced peripheral neuropathy and neurotoxicity effects

BACKGROUND

Chronic exposure to n-hexane can lead to peripheral neuropathy that no effective treatment regimen could be applied presently. This study investigated whether myelin protein zero (P0) protein and its antibody could be used to distinguish n-hexane intoxication and protect workers from peripheral neuropathy.

METHODS

We compared P0 protein and its antibody among three levels of n-hexane-exposed groups, which included 18 patients with n-hexane-induced peripheral neuropathy as case group, 120 n-hexane-exposed workers as n-hexaneexposed control group, and 147 non-hexane-exposed participants used as control group. ELISA method was applied to detect P0 protein and its antibody.

RESULTS

P0 protein in serum was significantly higher in the case group and n-hexane-exposed control group in comparison with the control group (P < 0.01). Compared with the n-hexane-exposed control group, the case group also had significant increase of P0 protein (P < 0.01). After 6 months therapy, P0 protein was observed to decrease significantly in the case group (P < 0.01). The P0 antibody in serum was significantly higher in the n-hexane-exposed control group than in the control group (P < 0.01), but not significantly different between cases and controls.

CONCLUSIONS

P0 antibodies in serum may be a short-term effect biomarker for n-hexane exposure. P0 protein in serum may be an early effective biomarker for peripheral nerve neuropathy and its biological limit value needs investigation in the future study.

Global and MGMT promoter hypomethylation independently associated with genomic instability of lymphocytes in subjects exposed to high-dose polycyclic aromatic hydrocarbon

Global hypomethylation, gene-specific methylation, and genome instability are common events in tumorigenesis. To date, few studies have examined the aberrant DNA methylation patterns in coke oven workers, who are highly at risk of lung cancer by occupational exposure to polycyclic aromatic hydrocarbons (PAHs). We recruited 82 PAH-exposed workers and 62 unexposed controls, assessed exposure levels by urinary 1-hydroxypyrene, and measured genetic damages by comet assay, bleomycin sensitivity, and micronucleus assay. The PAHs in coke oven emissions (COE) were estimated based on toxic equivalency factors. We used bisulfite-PCR pyrosequencing to quantitate DNA methylation in long interspersed nuclear element-1 (LINE-1) and O(6)-methylguanine-DNA methyltransferase (MGMT). Further, the methylation alteration was also investigated in COE-treated human bronchial epithelial (16HBE) cells. We found there are higher levels of PAHs in COE. Among PAH-exposed workers, LINE-1 and MGMT methylation levels (with CpG site specificity) were significantly lowered. LINE-1, MGMT, and its hot CpG site-specific methylation were negatively correlated with urinary 1-hydroxypyrene levels (r = -0.329, p < 0.001; r = -0.164, p = 0.049 and r = -0.176, p = 0.034, respectively). In addition, LINE-1 methylation was inversely associated with comet tail moment and micronucleus frequency, and a significant increase of micronucleus in low MGMT methylation group. In vitro study revealed that treatment of COE in 16HBE cells resulted in higher production of BPDE-DNA adducts, LINE-1 hypomethylation, hypomethylation, and suppression of MGMT expression. These findings suggest hypomethylation of LINE-1 and MGMT promoter could be used as markers for PAHs exposure and merit further investigation.

[Association between cytokines and trichloroethylene-induced hypersensitivity dermatitis]

OBJECTIVE

To detect the cytokines levels in serums of patients with trichloroethylene-induced hypersensitivity dermatitis and explore the effect biomarkers associated with this disease.

METHODS

Twenty-two patients with TCE-induced hypersensitivity dermatitis, twenty-two healthy TCE-exposed workers from the same workshops with patients and twenty-two comparable unexposed controls were recruited in this study. Eight cytokines in serums from all subjects were detected using Liquid Suspended Biochip; the correlation among the eight cytokines including interleukin (IL)-1β (IL-1β), IL-5, IL-8, IL-10, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), macrophage chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1β (MIP-1β) and the correlation between IL-5 and eosinophil count were analyzed.

RESULTS

The medians of levels of IL-1β, IFN-γ, IL-5, IL-10, MCP-1, MIP-1β, IL-8 among patients were 0.15, 80.13, 2.95, 6.45, 83.83, 1057.90, 440.22 pg/ml, respectively, which were higher than those among the TCE-exposed workers (0.09, 16.93, 0.11, 0.07, 28.75, 241.07, 28.26 pg/ml, respectively, all P values < 0.01) and unexposed controls (0.09, 3.14, 0.11, 0.07, 25.27, 209.64, 207.34 pg/ml, respectively, all P values < 0.01). The median of level of TNF-α among the patients was 13.26 pg/ml, which was significantly higher than that among TCE-exposed workers (4.87 pg/ml, P < 0.01) but not among unexposed controls; the median of level of IL-5 among the TCE-exposed workers was 0.11 pg/ml, which was significantly higher than that among the unexposed controls (0.11 pg/ml, P < 0.01). The median of levels of IL-8 among the unexposed controls was 207.34 pg/ml, which was significantly higher than that among the TCE-exposed workers (28.26 pg/ml, P < 0.01). In case group, except for correlation of TNF-α and IFN-γ, TNF-α and IL-5, the significant positive correlations were found among any two cytokines (r(IL-1β,IFN-γ) = 0.500, r(IL-1β,TNF-α) = 0.348, r(IL-1β,MCP-1) = 0.537, r(IL-1β,MIP-1β) = 0.477, r(IL-1β,IL-8) = 0.466, r(IL-1β,IL-5) = 0.610, r(IL-1β,IL-10) = 0.626, r(IFN-γ,MCP-1) = 0.460, r(IFN-γ,MIP-1β) = 0.491, r(IFN-γ,IL-8) = 0.322, r(IFN-γ,IL-5) = 0.532, r(IFN-γ,IL-10) = 0.511, r(TNF-α,MCP-1) = 0.325, r(TNF-α,MIP-1β) = 0.283, r(TNF-α,IL-8) = 0.430, r(TNF-α,IL-10) = 0.271, r(MCP-1,MIP-1β) = 0.659, r(MCP-1,IL-8) = 0.526, r(MCP-1,IL-5) = 0.504, r(MCP-1,IL-10) = 0.614, r(MIP-1β,IL-8) = 0.601, r(MIP-1β,IL-5) = 0.451, r(MIP-1β,IL-10) = 0.579, r(IL-8,IL-5) = 0.255, r(IL-8,IL-10) = 0.403, r(IL-5,IL-10) = 0.798, all P values < 0.05). The median of level of IL-5 among the patients with high eosinophils counts was 8.92 pg/ml, which was significantly higher than that among the patients with low eosinophils counts (1.04 pg/ml, P < 0.05).

CONCLUSION

The abnormal production of IL-1β, IFN-γ, TNF-α, IL-8, MCP-1, MIP-1β, IL-5 and IL-10 was related with the pathogenesis of hypersensitivity dermatitis induced by TCE. These cytokines could be used as referential indexes in the early health surveillance and clinic disease treatment.

Genetic damage induced by organic extract of coke oven emissions on human bronchial epithelial cells

Coke oven emissions are known as human carcinogen, which is a complex mixture of polycyclic aromatic hydrocarbon. In this study, we aimed to clarify the mechanism of action of coke oven emissions induced carcinogenesis and to identify biomarkers of early biological effects in a human bronchial epithelial cell line with CYP1A1 activity (HBE-CYP1A1). Particulate matter was collected in the oven area on glass filter, extracted and analyzed by GC/MS. DNA breaks and oxidative damage were evaluated by alkaline and endonucleases (FPG, hOGG1 and ENDO III)-modified comet assays. Cytotoxicity and chromosomal damage were assessed by the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay. The cells were treated with organic extract of coke oven emissions (OE-COE) representing 5, 10, 20, 40μg/mL extract for 24h. We found that there was a dose-effect relationship between the OE-COE and the direct DNA damage presented by tail length, tail intensity and Olive tail moment in the comet assay. The presence of lesion-specific endonucleases in the assays increased DNA migration after OE-COE treatment when compared to those without enzymes, which indicated that OE-COE produced oxidative damage at the level of pyrimidine and purine bases. The dose-dependent increase of micronuclei, nucleoplasmic bridges and nuclear buds in exposed cells was significant, indicating chromosomal and genomic damage induced by OE-COE. Based on the cytotoxic biomarkers in CBMN-Cyt assay, OE-COE may inhibit nuclear division, interfere with apoptosis, or induce cell necrosis. This study indicates that OE-COE exposure can induce DNA breaks/oxidative damage and genomic instability in HBE-CYP1A1 cells. The FPG-comet assay appears more specific for detecting oxidative DNA damage induced by complex mixtures of genotoxic substances.

[Analysis of subgroups of lymphocyte in peripheral blood among dermatitis medicamentosa-like of trichloroethylene patients and healthy exposed workers]

OBJECTIVE

To study the effects of trichloroethylene (TCE) to lymphocyte subsets among exposed workers, and explore the early immunological effect biomarkers for prevention of hypersensitivity dermatitis induced by TCE.

METHODS

Twenty-eight patients with TCE-induced hypersensitivity dermatitis, 56 healthy TCE-exposed workers from the same workshops with patients, and 28 comparable unexposed controls were recruited in this study. The total lymphocyte count and the major lymphocyte subsets including T cell, CD4(+) T cell, CD8(+) T cell, B cell, NK cell in peripheral blood were measured by Flow Cytometer analysis and Standard blood count analysis.

RESULTS

The total lymphocyte count and T cell, CD4(+) T cell, CD8(+) T cell among patients (median at 2810.00, 1846.17, 831.87, 904.05 cell counts/µl blood) were significantly increased compared with TCE-exposed workers (median at 2101.00, 1218.59, 643.87, 482.81 cell counts/µl blood, Z = -3.19, -4.96, -3.22, -4.99, P < 0.001) and unexposed controls (median at 1900.00, 1223.60, 558.60, 325.80 cell counts/µl blood, Z = -3.30, -4.46, -3.45, -5.03, P < 0.001), the NK cell and CD3(+)CD4(+)/CD3(+)CD8(+) ratio among patients (median at 255.50 cell counts/µl blood and 1.11) were significantly decreased compared with the unexposed controls (median at 642.60 cell counts/µl blood and 1.96, Z = -3.56 and -3.11, P < 0.01). Meanwhile, for the exposed workers, the CD8(+) T cell (median at 482.81 cell counts/µl blood) was significantly increased and the NK cell and CD3(+)CD4(+)/CD3(+)CD8(+) ratio (median at 318.76 cell counts/µl blood and 1.27) were significantly decreased compared with unexposed controls (median at 325.80 and 642.60 cell counts/µl blood and 1.96, Z = -2.63, -3.52, -2.29, P < 0.05).

CONCLUSION

Occupational exposure to TCE could affect the lymphocyte subsets, especially T cell and NK cell. The total lymphocyte count, T cell and CD4(+) T cell might be effect biomarkers for subjects with hypersensitivity dermatitis among TCE-exposed workers.

Modulation of DNA repair capacity by ataxia telangiectasia mutated gene polymorphisms among polycyclic aromatic hydrocarbons-exposed workers

The purpose of this study was to address the association between the ataxia telangiectasia mutated (ATM) gene polymorphisms and susceptibility to DNA repair capacity (DRC) among polycyclic aromatic hydrocarbons (PAHs)-exposed workers. Polymorphisms of ATM were genotyped. DRC was determined by comet assay. Chromosomal damage was detected by cytokinesis-block micronucleus (CBMN) assay. Flow cytometry was used to detect the distributions of cell cycle. Expressions of ATM and rH2AX were determined by immunoblotting analysis. Luciferase assays were performed to determine the functional difference of ATM promoter region allele. Subjects carrying T allele of rs228589 had significantly lower DRC compared with those with AA genotype. Subjects carrying G allele of rs652311 had significantly lower DRC than those with zero copy number of haplotype CGGT. SH ataxia telangiectasia mutated (SHATM) cells had significantly lower DRC than SH green fluorescent protein (SHGFP) cells induced by bleomycin and higher CBMN frequencies treated by benzo(a)pyrene [B(a)P] than SHGFP cells. After B(a)P treatment, a decrease in the percentage of G1 phase cells was observed in SHATM cells compared with SHGFP cells, rH2AX expressions were increased in SHATM cells and SHGFP cells, but ATM expressions had no change in 16HBE-SHGFP cells and HEK-SHGFP cells. Luciferase expression was not different between rs228589T and rs228589A plasmid constructs. In conclusions, it is suggested that ATM polymorphisms are associated with DRC among PAHs-exposed workers and ATM plays key roles in repair of chromosomal damage and cell cycle control with the treatment of B(a)P.

The effect of 2,5-hexanedione on myelin protein zero expression, and its mitigation using Ginkgo biloba extract

OBJECTIVE

To investigate the role of myelin protein zero (P(0)) in 2,5-hexanedione (2,5-HD)-induced peripheral nerve injury, and the protective effect of Ginkgo biloba extract (Egb761) on 2,5-HD-induced toxic peripheral neuropathy.

METHODS

After 4 weeks of treatment with 2,5-HD at different doses (50, 100, 200, 400 mg/kg) in rats, changes in the levels of P(0) in rat sciatic nerves was investigated, and the effect of Egb761 on 2,5-HD-induced toxic peripheral neuropathy was studied.

RESULTS

The blood-nerve barrier (BNB) permeability of the sciatic nerve increased, and the expression of P(0) mRNA and P(0) protein decreased in a dose-dependent manner after treatment with 2,5-HD for 4 weeks. Pretreatment with Egb761 protected against BNB interruption, and inhibited P(0) mRNA and protein reduction during 2,5-HD treatment. Pretreatment with Egb761 significantly reduced loss of body weight (P<0.01) and mitigated gait abnormalities (2.85±0.22) induced by 400 mg/kg 2,5-HD (P<0.01). It also reduced the signs of neurotoxicity induced by 2,5-HD.

CONCLUSION

2,5-HD inhibited the expression of P(0) in a dose-dependent manner, and this may be an important mechanism by which toxic peripheral neuropathy is induced by 2,5-HD. Egb761 has a protective effect against 2,5-HD-induced peripheral neurotoxicity in rats.

[Association between polymorphisms of metabolic genes and telomere length in workers exposed to polycyclic aromatic hydrocarbon]

OBJECTIVE

To investigate the association between the polymorphisms of metabolic genes and telomere length of genomic DNA in peripheral blood of workers exposed to polycyclic aromatic hydrocarbons (PAHs).

METHODS

One hundred and forty five coke-oven workers exposed to PAHs and sixty eight non-exposed medical staffs were recruited in this study. Urinary 1-hydroxypyrene (1-OHP) served as the internal exposure dose of PAHs for all subjects. Relative telomere length (RTL) of genomic DNA in peripheral blood was used as telomere length and measured by real-time PCR. Polymorphisms of metabolic genes were detected by PCR-based methods.

RESULTS

Compared with control group, the exposure group shown a decreased RTL (1.10 +/- 0.75 vs 1.43 +/- 1.06, P < 0.05). In the coke-oven workers, after adjusting the sex, age, cigarettes per day and urinary 1-OHP, RTL (1.25 +/- 0.93) of workers with CT genotype at the CYP1A1 3801 T > C was significantly longer than that (0.93 +/- 0.51) of workers with TT genotype (P < 0.05). RTL (0.90 +/- 0.58) of individuals with the Tyr/His genotype at mEH Tyr113His was significantly shorter than that (1.24 +/- 0.90) of individuals with the Tyr/Tyr genotype (P < 0.05). RTL (1.02 +/- 0.64) of individuals with the CT genotype at AHR rs10250822 was significantly shorter than that (1.36 +/- 1.14) of individuals with the CC genotype (P < 0.05). RTL (0.93 +/- 0.54) of individuals with the AT genotype at AHR rs10247158 was significantly shorter than that (1.19 +/- 0.84) of individuals with the AA genotype (P < 0.05).

CONCLUSION

The results of present study suggested that PAHs exposure could induce the shorted RTL, CYP1A1, mEH, AHR polymorphisms might influence the change of telomere length of genomic DNA in peripheral blood of workers exposed to PAHs.

[Hypermethylation of O(6)-methylguanine-DNA methyltransferase in human bronchial epithelial cell induced by organic extracts of coke oven emissions]

OBJECTIVE

To elucidate the mechanism of carcinogenesis induced by coke oven emissions by investigating the cell genetic damage index and the methylation of O⁶-methylguanine-DNA methyltransferase (MGMT).

METHODS

The human bronchial epithelial cell 16HBE was treated by 1 µmol/L B(a)P for 48 h, and then was exposed continuously to either 1‰ dimethyl sulfoxide (DMSO) or organic extracts of coke oven emission (OE-COE) for five days at the concentrations of 0, 2.5, 5.0, 10.0 and 20.0 µg/ml. The methylation-specific PCR (MSP-PCR), RT-PCR and immunoblotting were applied to detect the methylation status, changes of mRNA and protein of MGMT, respectively. Single cell gel electrophoresis was used to detect DNA damage induced by OE-COE.

RESULTS

Compared with the control group (DMSO), there was a significant hypermethylation in all study groups, along with the suppression of mRNA and protein in a dose-dependent manner, and the gradation ratio of them was 1.0, 0.96, 0.96, 0.85, 0.32 and 1.0, 1.0, 1.1, 0.41, 0.52, separately. There was a significant DNA damage with a dose-effect relationship in all study groups (F = 41.22, P < 0.05), and the comet Olive tail moment was (2.98 ± 1.43), (4.76 ± 1.79), (10.09 ± 1.75), (11.38 ± 1.77), (11.67 ± 1.88). The further study found that the index of DNA damage was negatively correlated to the expression of MGMT mRNA and its protein.

CONCLUSION

The DNA damage induced by COE might be associated with the suppression of MGMT caused by its hypermethylation.

[Association between telomere length and occupational polycyclic aromatic hydrocarbons exposure]

OBJECTIVE

To explore the association between polycyclic aromatic hydrocarbons (PAHs) exposure and telomere length (TL), so as to investigate the effective biomarkers to evaluate the genetic damage in peripheral blood of workers exposed to PAHs.

METHODS

The exposure group consisted of 145 coke-oven workers (including 30 top-oven workers, 76 side-oven workers and 39 bottom-oven workers), and the non-exposure control group comprised 68 medical staffs. At 6 hours after the weekend duty shift, the samples of urine and 1 ml venous blood were collected from each subject. Airborne benzene-soluble matter (BSM) and particulate-phase B(a)P in the working environment of coke-oven and controls were sampled and analyzed. The concentration of urinary 1-hydroxypyrene (1-OHPyr) was determined. A real-time PCR method was used to determine the relative telomere length (RTL) of genomic DNA in peripheral blood. The relationship between the RTL and external exposure of PAHs, the potential factors which might have influence on TL were analyzed.

RESULTS

The medians of air BSM and particulate-phase B(a)P were higher in coke-oven (BSM: 328.6 µg/m(3); B(a)P: 926.9 ng/m(3)) than those in control working environment (BSM:97.8 µg/m(3); B(a)P: 49.1 ng/m(3)). The level of 1-OHPyr among coke-oven workers was significantly higher than that of non-exposed group (12.2 µmol/mol Cr vs 0.7 µmol/mol Cr; t = 26.971, P < 0.01). RTL in coke-oven workers were significantly shorter than those of controls (1.10 ± 0.75 vs 1.43 ± 1.06; t = 2.263, P = 0.026), and after adjusting for cigarettes per day and urinary 1-OHPyr, the significant difference was still observed (F(adju) = 5.496, P(adju) = 0.020). Stratification analysis found that RTL among the male and non-drinking groups in coke-oven workers were shorter than those the same sex and alcohol using status in controls (1.08 ± 0.73 vs 1.51 ± 1.10, F = 9.212, P = 0.003; 0.96 ± 0.38 vs 1.26 ± 0.46, F = 6.484, P = 0.012). Significant correlation between RTL and age was found (r = -0.284, P = 0.019) in non-exposure group.

CONCLUSION

PAH-exposure has effect on TL of genomic DNA in peripheral blood, which is mainly observed in the male and non-drinking groups between PAH-exposed workers and controls. It indicates that TL of genomic DNA in peripheral blood might be an effective biomarker as PAH-induced genetic damage.

[Effect of 2,5-hexanedione on myelin protein zero in sciatic nerve and its antibody in serum of rats at different time points]

OBJECTIVE

To explore the effects of 2,5-hexandione, the metabolite of n-hexane, on the expression of myelin protein zero (P0) in sciatic nerve and on the positive rate of P0 antibody in serum of rats at different time points.

METHODS

Seventy five Wistar rats were divided into five groups and were administrated with 400 mg/kg 2,5-hexanedione per day for 0, 1, 2, 3 and 4 weeks respectively. The P0 expression at different time points was determined with immunohischemistry and the P0 antibody in serum were detected with enzyme-linked immunosorbent assay.

RESULTS

With the administration of 2,5-hexandione, the rats gradually showed the signs of peripheral neuropathy. P0 distribution in transverse section of sciatic nerve was different, and the intensity in myelin sheath was higher than that in axon. The expression of P0 in sciatic nerve of rats with 2,5-hexanedione administration for 0 week seemed higher than those of the other time points, and the expression of the P0 showed a decreasing tendency with the time of 2,5-hexanedione administration. The positive rate of P0 antibody in serum of rats administrated with 400 mg/kg 2,5-hexanedione for 0, 1, 2, 3 and 4 weeks were 33.3%, 26.7%, 46.7%, 46.7% and 84.6% respectively. The positive rate of Po antibodies in serum of rats showed an increasing tendency with the time of 2,5-hexanedione administration (chi2 = 11.007, P < 0.05).

CONCLUSION

The P0 in sciatic nerve of rats could be destroyed by 2,5-hexanedione and P0 expression level decreased with the time of 2,5-hexanedione administration. The positive rate of P0 antibody in serum increased with the time of 2,5-hexanedione administration in rats.

[Cytotoxicity and genomic damage of benzo[a]pyrene in gene transformed cell model]

OBJECTIVE

To investigate cytotoxicity and genotoxicity of benzo(a)pyrene (B(a)P) by 16HBE-CYP1A1 cells which are human bronchial epithelial cell with CYP1A1 transformed.

METHODS

Expression of CYP1A1 and mEH of cell models were tested by real-time quantitative polymerase chain reaction. Cells were treated with 0, 1, 5, 10 and 20 micromol/L B(a)P for 24 h. Adverse effects of B(a)P were tested by cytokinesis-block micronucleus (CBMN) cytome assays. Cytotoxicity was assessed by the nuclear division index (NDI), frequency of necrotic and apoptotic cells. Genetic damages were assessed by frequencies of CBMN, nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs).

RESULTS

High levels of CYP1A1 and mEH were found in 16HBE-CYP1A1 cells (relative mRNA content was 7.8 x 10(-4) and 0.030 respectively). In 16HBE-CYP1A1 cells, NDI were decreased in 1, 5, 10 and 20 micromol/L B(a)P treated groups, 1.92 +/- 0.04, 1.71 +/- 0.01, 1.61 +/- 0.04, and 1.41 +/- 0.01, respectively; and lower than control group (2.08 +/- 0.03). Compared with control group ((82.67 +/- 6.66)%), the binucleated cells ratios were decreased, (76.33 +/- 3.51)%, (66.33 +/- 0.58)%, (51.67 +/- 1.53)% and (39.0 +/- 1.0)% respectively.Necrotic cells ratios were (1.93 +/- 0.42)%, (2.20 +/- 0.53)%, (8.07 +/- 0.90)% and (15.27 +/- 2.80)%, respectively, higher than control group ((0.47 +/- 0.11)%). The differences were significant (F values were 899.94, 303.33, 240.87, P < 0.01). Apoptotic cells were increased at lower groups and decreased to normal at higher groups treated by B(a)P. They were (1.20 +/- 0.53)%, (2.00 +/- 0.20)%, (1.47 +/- 0.12)%, (1.20 +/- 0.00)% and (1.20 +/- 0.00)%, respectively. Analysis on biomarkers of genetic damage, the significant dose-effect relationship were observed in NPBs and NBUDs (F values were 50.23, 121.09, P < 0.01, respectively). Frequencies of NPBs were (4.67 +/- 2.89) per thousand, (7.33 +/- 1.53) per thousand, (10.67 +/- 2.08) per thousand and (11.00 +/- 1.00) per thousand respectively. Frequencies of NBUDs were (2.33 +/- 0.58) per thousand, (4.00 +/- 1.00) per thousand, (5.00 +/- 1.00) per thousand, and (7.67 +/- 1.16) per thousand respectively. However, the dose-relationship of CBMN last only to 10 micromol/L B(a)P treated groups in 16HBE-CYP1A1 cells, and frequencies of CBMN were (8.33 +/- 3.21) per thousand, (14.67 +/- 1.15) per thousand, respectively. Frequency of CBMN was (16.67 +/- 2.88) per thousand in 20 micromol/L B(a)P treated group, lower than 10 micromol/L B(a)P treated group ((17.67 +/- 2.08) per thousand). In 16HBEV control cells, the cytotoxicity was found only in higher B(a)P treated groups and frequencies of CBMN, NPBs and NBUDs were increased also. While no significant differences were observed between 5, 10, 20 micromol/L B(a)P treated groups (they were (6.37 +/- 2.08) per thousand, (9.33 +/- 1.52) per thousand, (9.33 +/- 3.21) per thousand; (4.33 +/- 1.53) per thousand, (6.00 +/- 2.65) per thousand, (5.33 +/- 1.53) per thousand and (2.33 +/- 0.58) per thousand, (3.33 +/- 1.16) per thousand, (3.67 +/- 1.16) per thousand, respectively).

CONCLUSIONS

The genetic damages were more severe after treated with activated B(a)P, which may be induced by decreased NDI, increased necrotic cells and inhibition of apoptosis.

The effect of 2,5-hexanedione on permeability of blood-nerve barrier in rats

To explore the effect of 2,5-hexanedione on permeability of blood-nerve barrier, adult Wistar rats were administered with 400 mg x kg(-1) x d(- 1) 2,5-hexanedione to establish animal model of 2,5-hexnedione neuropathy. Evans blue was injected through left femoral vein of the rats after the model had been established. The distribution of fluorescence in sciatic-tibial nerve was observed and assessed. For the transverse sections of sciatic-tibial nerves, the average fluorescence intensity of proximal section was stronger (p < .01) than those of intermediate and distal sections and the average fluorescence intensity of intermediate section was stronger (p < .01) than that of distal section in the intoxicated group. In the control, the weak fluorescence was shown, and average fluorescence intensity of distal section was stronger (p < .05) than that of proximal section. The average fluorescence intensity of proximal, intermediate and distal sections in the intoxicated group was stronger (p < .01) than those of the corresponding sections in the control. For the longitudinal sections of sciatic-tibial nerves, fluorescence was observed in both proximal and distal sections in the intoxicated group. The fluorescence intensity of distal section in the control was weak and almost no fluorescence was shown in the proximal section. The permeability of blood-nerve barrier could be increased by 2,5-hexanedione.

[The effect of 2,5-hexanedione on nerve growth factor in sciatic nerve of rats and VSC4.1 cell]

OBJECTIVE

To explore the effect of 2,5-hexanedione (2,5-HD) on the levels of nerve growth factor (NGF) in sciatic nerve of rats and motor-neurons.

METHOD

A total of 50 Wistar rats were randomly designed into five groups and intoxicated with 400 mgxkg(-1)xd(-1) 2,5-HD for 0, 7, 14, 21, 28 d. Immunohistochemistry and real-time PCR were used to detect the levels of NGF and NGF mRNA. Motor neuron VSC4.1 cells were administrated with 0, 2.5, 5.0, 10.0, 20.0 mmol/L 2,5-HD for 24 h and 10.0 mmol/L 2,5-HD was chosen to intoxicated VSC4.1 cells for 0, 1, 3, 6, 12, 24, 48 h respectively. Immunofluorescence technique was selected to detect the levels of NGF.

RESULTS

The NGF level in sciatic nerve of rats administrated with 400 mgxkg(-1)xd(-1) 2,5-HD showed increase tendency at begin and then decrease after exposure. The NGF mRNA level in 14 d (2(-DeltaDeltaCt)= 3.46), 21 d (2(-DeltaDeltaCt)= 5.28) and 28 d (2(-DeltaDeltaCt)= 3.10) were higher than those in 0 d (2(-DeltaDeltaCt)= 1) and 7 d (2(-DeltaDeltaCt)= 0.78). In vitro tests of VSC4.1 cells showed that NGF levels in 5.0 mmol/L (43.24 +/- 7.52), 10.0 mmol/L (43.48 +/- 10.86) and 20.0 mmol/L (63.13 +/- 10.68) were higher than those in 0 mmol/L (16.32 +/- 4.20)(q values were 19.92, 19.72, 32.78, respectively, P < 0.01) and 2.5 mmol/L (19.78 +/- 2.66) (q values were 17.50, 17.42, 30.63, respectively, P < 0.01) in 24 h and the NGF level in 20.0 mmol/L was higher than those in 5.0 mmol/L (q = 13.04, P < 0.01) and 10.0 mmol/L (q = 11.71, P < 0.01). The NGF levels of VSC4.1 cells with 10.0 mmol/L 2,5-HD in 6 h (18.66 +/- 2.89), 12 h (23.14 +/- 6.08), 24 h (27.66 +/- 6.11) and 48 h (17.25 +/- 3.05) were increased compared with that in 0 h (10.18 +/- 1.81) (q values were 9.64, 15.74, 21.76, 8.50, respectively, P < 0.01), 1 h (9.31 +/- 1.28) (q values were 10.28, 16.17, 21.95, 9.20, respectively, P < 0.01) and 3 h (10.44 +/- 2.13) (q values were 9.25, 15.24, 21.17, 8.10, respectively, P < 0.01), and NGF levels in 12 h and 24 h increased compared with those in 6 h (q values were 5.24, 10.77, respectively, P < 0.01) and 48 h (q values were 7.31, 13.26, respectively, P < 0.01).

CONCLUSION

2,5-HD could increase NGF levels in sciatic nerve of rats and motor-neurons, and the dose or time dependent effects were observed in this study.

[Study on the influence factors of human peripheral blood B lymphocyte transformation by Epstein-Barr virus]

OBJECTIVE

To investigate the influence factors of human peripheral blood B lymphocyte transformation by epstein-barr virus (EBV).

METHODS

EB virus was obtained from B95-8 supernatant and quantitated by quantitative PCR amplification. The concentration of cyclosporine A (CSA) concentration of lymphocytes and different time of adding CSA to culture media were selected to examine the effects on the lymphocyte transformation, and the condition of lymphocyte transformation of worker exposed to trichloroethylene was further confirmed.

RESULTS

The titer of two virus samples were 5.45 x 10(6) and 1.06 x 10(6) copies/ml. Peripheral blood mononuclear cells (PBMCs) was transformed by using CSA at different concentration and adding time to culture fluid. The concentration of PBMCs being transformed was 2 x 10(6)/ml for normal people, but 1 x 10(6)/ml for worker exposed to trichloroethylene. Cell transformation was confirmed by the gradual increase of cell size and cellular clusters.

CONCLUSION

The results suggest the key issue is PBMCs being transformed at a concentration of 2 x 10(6)/ml, rather than using CSA at different concentration and adding time to culture fluid. The PBMCs at concentration of 1 x 10(6)/ml for worker exposed to trichloroethylene were transformed, which may be associated with sensitized status of lymphocytes.