Abstract Introduction Exposure to diesel engine exhaust (DEE) is associated with increased lung cancer risk; however, underlying molecular mechanisms remain unclear. We apply an exposome approach to characterize early biological effects of occupational DEE exposure. Methods Plasma samples from 54 diesel engine factory workers and 55 non-exposed control workers were characterized using an integrated exposome platform that combines untargeted gas chromatography (GC-) and liquid chromatography (LC-) with high-resolution mass spectrometry (HRMS). Exposome profiles were evaluated by metabolome-wide association study (MWAS) for molecular features associated with DEE exposure and elemental carbon. Potential molecular mechanisms underlying DEE were further evaluated by integrating exposome profiles with plasma proteomics, urine aminopyrenes and mutagenicity, and buccal gene expression analysis. Results GC- and LC-HRMS untargeted analysis detected 68,285 metabolic features. Comparison of DEE-exposed and non-exposed workers identified 772 molecular features associated with exposure at a FDR <5%, including 102 detected using GC-HRMS and 670 detected using LC-HRMS. Molecular networking and annotation identified compounds consistent with DEE exposure, while metabolic pathway enrichment suggest alterations in oxidative stress and endothelial pathways. We conducted a secondary MWAS to link urinary mutagenicity, reflecting systemic exposure to genotoxic/carcinogenic agents, and associated with tumor development and identified 90 molecular features positively associated with urine mutagenicity at FDR<5%. Discussion Integration of exposome profiles with protein and genome-wide gene expression identified biological alterations consistent with many of the key characteristics of carcinogens. Conclusion Integrated exposome characterization of DEE exposure identified novel DEE biomarkers and biological response profiles in a high exposure setting.

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 (ptrend = .001, FDR = 0.04) and miR‐93‐5p (ptrend = .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.

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-nitro-fluorene 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-amino-pyrene 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.

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/m 3 ), below the European Union (EU) OEL (<50 µg/m 3 ) and below the American Conference of Governmental Industrial Hygienists (ACGIH) recommendation (<20 µg/m 3 ). 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 (p trend =0.01, FDR=0.19) and gene expression (p trend =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.

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.

Urinary mutagenicity reflects systemic exposure to complex mixtures of genotoxic/carcinogenic agents and is linked to tumor development. Coal combustion emissions (CCE) and diesel engine exhaust (DEE) are associated with cancers of the lung and other sites, but their influence on urinary mutagenicity is unclear. We investigated associations between exposure to CCE or DEE and urinary mutagenicity. In two separate cross-sectional studies of nonsmokers, organic extracts of urine were evaluated for mutagenicity levels using strain YG1041 in the Salmonella (Ames) mutagenicity assay. First, we compared levels among 10 female bituminous (smoky) coal users from Laibin, Xuanwei, China, and 10 female anthracite (smokeless) coal users. We estimated exposure–response relationships using indoor air concentrations of two carcinogens in CCE relevant to lung cancer, 5-methylchrysene (5MC), and benzo[ a ]pyrene (B[ a ]P). Second, we compared levels among 20 highly exposed male diesel factory workers and 15 unexposed male controls; we evaluated exposure-response relationships using elemental carbon (EC) as a DEE-surrogate. Age-adjusted linear regression was used to estimate associations. Laibin smoky coal users had significantly higher average urinary mutagenicity levels compared to smokeless coal users (28.4 ± 14.0 SD vs. 0.9 ± 2.8 SD rev/ml-eq, p  = 2 × 10 −5 ) and a significant exposure-response relationship with 5MC ( p  = 7 × 10 −4 ). DEE-exposed workers had significantly higher urinary mutagenicity levels compared to unexposed controls (13.0 ± 10.1 SD vs. 5.6 ± 4.4 SD rev/ml-eq, p  = .02) and a significant exposure-response relationship with EC ( p -trend = 2 × 10 −3 ). Exposure to CCE and DEE is associated with urinary mutagenicity, suggesting systemic exposure to mutagens, potentially contributing to cancer risk and development at various sites.

Urinary mutagenicity reflects systemic exposure to complex mixtures of genotoxic/carcinogenic agents and is linked to tumor development. Coal combustion emissions (CCE) and diesel engine exhaust (DEE) are associated with cancers of the lung and other sites, but their influence on urinary mutagenicity is unclear. We investigated associations between exposure to CCE or DEE and urinary mutagenicity. In two separate cross-sectional studies of nonsmokers, organic extracts of urine were evaluated for mutagenicity levels using strain YG1041 in the Salmonella (Ames) mutagenicity assay. First, we compared levels among 10 female bituminous (smoky) coal users from Laibin, Xuanwei, China, and 10 female anthracite (smokeless) coal users. We estimated exposure-response relationships using indoor air concentrations of two carcinogens in CCE relevant to lung cancer, 5-methylchrysene (5MC), and benzo[a]pyrene (B[a]P). Second, we compared levels among 20 highly exposed male diesel factory workers and 15 unexposed male controls; we evaluated exposure-response relationships using elemental carbon (EC) as a DEE-surrogate. Age-adjusted linear regression was used to estimate associations. Laibin smoky coal users had significantly higher average urinary mutagenicity levels compared to smokeless coal users (28.4 +/- 14.0 SD vs. 0.9 +/- 2.8 SD rev/ml-eq, p = 2 x 10(-5)) and a significant exposure-response relationship with 5MC (p = 7 x 10(-4)). DEE-exposed workers had significantly higher urinary mutagenicity levels compared to unexposed controls (13.0 +/- 10.1 SD vs. 5.6 +/- 4.4 SD rev/ml-eq, p = .02) and a significant exposure-response relationship with EC (p-trend = 2 x 10(-3)). Exposure to CCE and DEE is associated with urinary mutagenicity, suggesting systemic exposure to mutagens, potentially contributing to cancer risk and development at various sites.

Abstract 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 <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 <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 <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 <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.

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.

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 mu g/m(3)) 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.

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 mu g/m(3)), 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.

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.

Objective To establish a simple and rapid method of micro-whole blood high-throughput comet assay for large sample population biomonitoring.Methods A non-smoker was invited as volunteer to explore the experimental conditions and establish the method of micro-whole blood high-throughput comet assay.The comet assay method was used in diesel engine testing workers for validation.Results Through the exploration of the amount of glue and cell suspensions,we found that 30μL cell suspensions were uniformly pipetted into the wells of a 20-well Comet Slide,and the gel surface was smooth,and cells were single layer distribution.After submerging lysis solution,the gel was not easy to fall off.We also found that the image of 5μtL of whole blood mixed with 200μtL agarose was clear.After running electrophoresis,the cells were dispersed evenly.The contrast ratio was higher.By validating the method of micro-whole blood highthroughput comet assay,it was found that the tail length,the Olive tail moment and percentage of tail DNA was notably increased in DEE-exposed workers.The value of coefficients of variation for inter plate and intraplate were less than 10％.Conclusions Micro-whole blood high-throughput comet assay could be used the detection of chemical carcinogens and genetic damage.

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.

Abstract Rationale: Recent epidemiological studies show that Diesel Engine Exhaust (DEE) exposure is associated with lung cancer, however the mechanism by which this occurs is not well understood. The goal of this study was to assess the transcriptomic alterations in the nasal epithelium of DEE exposed workers from factories where diesel engines are utilized. Methods: Nasal epithelium brushings were obtained from 41 subjects who work in a factory with DEE exposure, and 38 comparable control subjects who work in factories without any DEE exposure. The median Elemental Carbon (EC) levels of exposed individuals was 60.7μg/m3, with a range of 17.2-105.4 μg/m3, respectively. RNA was isolated from nasal epithelial cells, and profiled for gene expression using Affymetrix microarrays. Linear modeling was used to detect differential expression between DEE exposure and controls. Pathway enrichment in differentially expressed genes was assessed using GO Biological Process and KEGG terms via EnrichR. Results: We found 234 genes that were differentially expressed between samples derived from DEE exposed participants versus controls at FDR q < 0.25. Within this set of genes, we observed a higher expression of genes involved in oxidative stress response, as well as cell proliferation, cellular transcription, and regulation of apoptosis. In addition, we found that genes involved in ion transport, such as CFTR, were expressed at lower levels in DEE exposed samples. Conclusions: Chronic DEE exposure associates with changes in the airway transcriptome, with increased stress response as a major effect of DEE exposure. The transcriptomic alterations we identified may help provide insight into the underlying mechanisms of DEE carcinogenicity. Citation Format: Eduard I. Drizik, Sean Corbett, Roel Vermeulen, Yufei Dai, Wei Hu, Marc Lenburg, Dianzhi Ren, Huawei Duan, Yong Niu, Jun Xu, Wei Fu, Kees Meliefste, Baosen Zhou, JuFang Yang, Meng Ye, Xiaowei Jia, Tao Meng, Ping Bin, Yuxin Zheng, Debra Silverman, Nathaniel Rothman, Avrum Spira, Qing Lan. Impact of diesel engine exhaust exposure on the airway transcriptome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4256. doi:10.1158/1538-7445.AM2017-4256

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/m3) 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.

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.

Background: Silicosis is a respiratory disease caused by long-term silica dust exposure.Our previous study has demonstrated that silica mediates the activation of phosphatidylinositol 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN)/serine or threonine kinase (AKT)/mitogen-activated protein kinases (MAPK)/AP-1 pathway in human embryo lung fibroblasts (HELFs).The purpose of this study is to identify genome-wide aberrant DNA methylation profiling in lung tissues from silicosis patients.Methods: We performed Illumina Human Methylation 450K Beadchip arrays to investigate the methylation alteration in formalin-fixed, paraffin-embedded (FFPE) lung specimens, immunohistochemistry to detect the level of c-Jun and PTEN proteins; methylation specific PCR (MS-PCR) to identify PTEN and c-Jun promoter methylation in HELFs.Results: We found 86,770 CpG sites and 79,660 CpG sites significantly differed in methylation status in early-stage and advanced-stage compared with GEO normal lung methylation data.Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the methylated status of MAPK signaling pathway was considered changed.The number of PTEN and c-Jun CpG promoter methylated-sites were increased in advanced-stage.Early-stage showed the positive expression of c-Jun and PTEN protein and negative or mild expression in advanced-stage.PTEN promoter was no differentially methylated and c-Jun promoter differed at 12 and 24 h in HELFs.Conclusions: Abnormal DNA methylation on genome-scale was implicated in silicosis, and PTEN promoter hypermethylation might be associated with decrease of PTEN protein.

Introduction Diesel engine exhaust (DEE) is a known lung carcinogen in humans (IARC Group 1). However, the biological mechanism underlying this association is unclear. Given the suspected relationship between inflammation and lung carcinogenesis, we evaluated associations between DEE exposure and a multiplex panel of immune markers in workers exposed to DEE and unexposed workers in China. Methods A cross-sectional molecular epidemiology study was conducted among 54 workers exposed to DEE in a diesel engine testing facility, and 55 unexposed workers who were employed in separate factories. Repeated personal exposure measurements of elemental carbon (EC) were taken from workers before blood collection. Serum levels of immune markers were analysed using a Luminex bead-based assay. Linear regression was used to evaluate differences in marker concentrations between DEE exposed vs. unexposed workers, and to explore exposure-response trends with EC. Results Four markers were significantly associated with DEE exposure in analyses of exposed vs. unexposed workers (P-value < 0.05). Significant monotonic trends in relation to increasing EC levels were observed for CXCL-11/I-TAC (19% reduction in exposed workers overall) and CCL15/MIP-1D (21% increase in exposed workers overall). Analyses of DEE exposed vs. unexposed workers stratified by smoking status found that an additional marker (CCL2/MCP-1) was significantly increased in workers exposed to DEE among never and former smokers, but not current smokers (Pinteraction = 0.01). Conclusions Recent evidence suggests that higher levels of CCL15/MIP-1D and CCL2/MCP-1, two markers in the CC chemokine subfamily that attract white blood cells to sites of inflammation, are associated with increased risk of lung cancer in Asian never-smoking women. Alterations in these markers in the same direction among workers exposed to DEE in our study may provide mechanistic insight into the relationship between DEE and lung carcinogenesis.