Person:

Wang, Zhaoxi

Accumulating evidence demonstrates that particulate air pollutants can cause both pulmonary and airway inflammation. However, few data show that particulates can induce systemic inflammatory responses. We conducted an exploratory study using microarray techniques to analyze whole-blood total RNA in boilermakers before and after occupational exposure to metal fumes. A self-controlled study design was used to overcome the problems of larger between-individual variation interferences with observations of relatively smaller changes caused by environmental exposure. Moreover, we incorporated the dichotomous data of absolute gene expression status in the microarray analyses. Compared with nonexposed controls, we observed that genes with altered expression in response to particulate exposure were clustered in biologic processes related to inflammatory response, oxidative stress, intracellular signal transduction, cell cycle, and programmed cell death. In particular, the preinflammatory cytokine interleukin 8 and one of its receptors, chemokine receptor 4, seemed to play important roles in early-stage response to heavy metal exposure and were down-regulated. Furthermore, most observed expression variations were from nonsmoking exposed individuals, suggesting that smoking profoundly affects whole-blood expression profiles. Our study is the first to demonstrate that with a paired sampling study design of pre- and postexposed individuals, small changes in gene expression profiling can be measured in whole-blood total RNA from a population-based study. This technique can be applied to evaluate the host response to other forms of environmental exposures.

Background: Welding-associated air pollutants negatively affect the health of exposed workers; however, their molecular mechanisms in causing disease remain largely unclear. Few studies have systematically investigated the systemic toxic effects of welding fumes on humans. Objectives: To explore the effects of welding fumes on the plasma metabolome, and to identify biomarkers for risk assessment of welding fume exposure. Methods: The two-stage, self-controlled exploratory study included 11 boilermakers from a 2011 discovery panel and 8 boilermakers from a 2012 validation panel. Plasma samples were collected pre- and post-welding fume exposure and analyzed by chromatography/mass spectrometry. Results: Eicosapentaenoic or docosapentaenoic acid metabolic changes post-welding were significantly associated with particulate (PM2.5) exposure (p<0.05). The combined analysis by linear mixed-effects model showed that exposure was associated with a statistically significant decline in metabolite change of eicosapentaenoic acid [(95% CI) = −0.013(−0.022∼−0.004); p = 0.005], docosapentaenoic acid n3 [(95% CI) = −0.010(−0.018∼−0.002); p = 0.017], and docosapentaenoic acid n6 [(95% CI) = −0.007(−0.013∼−0.001); p = 0.021]. Pathway analysis identified an association of the unsaturated fatty acid pathway with exposure (pStudy−2011 = 0.025; pStudy−2012 = 0.021; pCombined = 0.009). The functional network built by these fatty acids and their interactive genes contained significant enrichment of genes associated with various diseases, including neoplasms, cardiovascular diseases, and lipid metabolism disorders. Conclusions: High-dose exposure of metal welding fumes decreases unsaturated fatty acids with an exposure-response relationship. This alteration in fatty acids is a potential biological mediator and biomarker for exposure-related health disorders.

Background: In occupational settings, boilermakers are exposed to high levels of metallic fine particulate matter (PM2.5) generated during the welding process. The effect of welding PM2.5 on heart rate variability (HRV) has been described, but the relationship between PM2.5, DNA methylation, and HRV is not known. Methods: In this repeated-measures panel study, we recorded resting HRV and measured DNA methylation levels in transposable elements Alu and long interspersed nuclear element-1 (LINE-1) in peripheral blood leukocytes under ambient conditions (pre-shift) and right after a welding task (post-shift) among 66 welders. We also monitored personal PM2.5 level in the ambient environment and during the welding procedure. Results: The concentration of welding PM2.5 was significantly higher than background levels in the union hall (0.43 mg/m3 vs. 0.11 mg/m3, p < 0.0001). The natural log of transformed power in the high frequency range (ln HF) had a significantly negative association with PM2.5 exposure (β = -0.76, p = 0.035). pNN10 and pNN20 also had a negative association with PM2.5 exposure (β = -0.16%, p = 0.006 and β = -0.13%, p = 0.030, respectively). PM2.5 was positively associated with LINE-1 methylation [β = 0.79%, 5-methylcytosince (%mC), p = 0.013]; adjusted for covariates. LINE-1 methylation did not show an independent association with HRV. Conclusions: Acute decline of HRV was observed following exposure to welding PM2.5 and evidence for an epigenetic response of transposable elements to short-term exposure to high-level metal-rich particulates was reported. Electronic supplementary material The online version of this article (doi:10.1186/1471-2458-14-1279) contains supplementary material, which is available to authorized users.

Background: Mitochondrial DNA (mtDNA) is a critical activator of inflammation and the innate immune system. However, mtDNA level has not been tested for its role as a biomarker in the intensive care unit (ICU). We hypothesized that circulating cell-free mtDNA levels would be associated with mortality and improve risk prediction in ICU patients. Methods and Findings: Analyses of mtDNA levels were performed on blood samples obtained from two prospective observational cohort studies of ICU patients (the Brigham and Women's Hospital Registry of Critical Illness [BWH RoCI, n = 200] and Molecular Epidemiology of Acute Respiratory Distress Syndrome [ME ARDS, n = 243]). mtDNA levels in plasma were assessed by measuring the copy number of the NADH dehydrogenase 1 gene using quantitative real-time PCR. Medical ICU patients with an elevated mtDNA level (≥3,200 copies/µl plasma) had increased odds of dying within 28 d of ICU admission in both the BWH RoCI (odds ratio [OR] 7.5, 95% CI 3.6–15.8, p = 1×10−7) and ME ARDS (OR 8.4, 95% CI 2.9–24.2, p = 9×10−5) cohorts, while no evidence for association was noted in non-medical ICU patients. The addition of an elevated mtDNA level improved the net reclassification index (NRI) of 28-d mortality among medical ICU patients when added to clinical models in both the BWH RoCI (NRI 79%, standard error 14%, p<1×10−4) and ME ARDS (NRI 55%, standard error 20%, p = 0.007) cohorts. In the BWH RoCI cohort, those with an elevated mtDNA level had an increased risk of death, even in analyses limited to patients with sepsis or acute respiratory distress syndrome. Study limitations include the lack of data elucidating the concise pathological roles of mtDNA in the patients, and the limited numbers of measurements for some of biomarkers. Conclusions: Increased mtDNA levels are associated with ICU mortality, and inclusion of mtDNA level improves risk prediction in medical ICU patients. Our data suggest that mtDNA could serve as a viable plasma biomarker in medical ICU patients. Please see later in the article for the Editors' Summary

Background: Early detection of the Acute Respiratory Distress Syndrome (ARDS) has the potential to improvethe prognosis of critically ill patients admitted to the intensive care unit (ICU). However, no reliable biomarkers are currently available for accurate early detection of ARDS in patients with predisposing conditions. Objectives: This study examined risk factors and biomarkers for ARDS development and mortality in two prospective cohort studies. Methods: We examined clinical risk factors for ARDS in a cohort of 178 patients in Beijing, China who were admitted to the ICU and were at high risk for ARDS. Identified biomarkers were then replicated in a second cohort of1,878 patients in Boston, USA. Results: Of 178 patients recruited from participating hospitals in Beijing, 75 developed ARDS. After multivariate adjustment, sepsis (odds ratio [OR]:5.58, 95% CI: 1.70–18.3), pulmonary injury (OR: 3.22; 95% CI: 1.60–6.47), and thrombocytopenia, defined as platelet count <80×103/µL, (OR: 2.67; 95% CI: 1.27–5.62)were significantly associated with increased risk of developing ARDS. Thrombocytopenia was also associated with increased mortality in patients who developed ARDS (adjusted hazard ratio [AHR]: 1.38, 95% CI: 1.07–1.57) but not in those who did not develop ARDS(AHR: 1.25, 95% CI: 0.96–1.62). The presence of both thrombocytopenia and ARDS substantially increased 60-daymortality. Sensitivity analyses showed that a platelet count of <100×103/µLin combination with ARDS provide the highest prognostic value for mortality. These associations were replicated in the cohort of US patients. Conclusions: This study of ICU patients in both China and US showed that thrombocytopenia is associated with an increased risk of ARDS and platelet count in combination with ARDS had a high predictive value for patient mortality.

Mutations in the mtDNA genome have long been suspected to play an important role in cancer. Although most cancer cells harbor mtDNA mutations, the question of whether such mutations are associated with clinical prognosis of lung cancer remains unclear. We resequenced the entire mitochondrial genomes of tumor tissue from a population of 250 Korean patients with non-small cell lung cancer (NSCLC). Our analysis revealed that the haplogroup (D/D4) was associated with worse overall survival (OS) of early-stage NSCLC [adjusted hazard ratio (AHR), 1.95; 95% CI, 1.14–3.33; Ptrend = 0.03]. By comparing the mtDNA variations between NSCLC tissues and matched blood samples, we found that haplogroups M/N and/or D/D4 were hotspots for somatic mutations, suggesting a more complicated mechanism of mtDNA somatic mutations other than the commonly accepted mechanism of sequential accumulation of mtDNA mutations.

Purpose Lung cancer, of which 85% is non–small-cell (NSCLC), is the leading cause of cancer-related death in the United States. We used genome-wide analysis of tumor tissue to investigate whether single nucleotide polymorphisms (SNPs) in tumors are prognostic factors in early-stage NSCLC.

Patients and Methods One hundred early-stage NSCLC patients from Massachusetts General Hospital (MGH) were used as a discovery set and 89 NSCLC patients collected by the National Institute of Occupational Health, Norway, were used as a validation set. DNA was extracted from flash-frozen lung tissue with at least 70% tumor cellularity. Genome-wide genotyping was done using the high-density SNP chip. Copy numbers were inferred using median smoothing after intensity normalization. Cox models were used to screen and validate significant SNPs associated with the overall survival.

Results Copy number gains in chromosomes 3q, 5p, and 8q were observed in both MGH and Norwegian cohorts. The top 50 SNPs associated with overall survival in the MGH cohort (P ≤ 2.5 × 10−4) were selected and examined using the Norwegian cohort. Five of the top 50 SNPs were validated in the Norwegian cohort with false discovery rate lower than 0.05 (P < .016) and all five were located in known genes: STK39, PCDH7, A2BP1, and EYA2. The numbers of risk alleles of the five SNPs showed a cumulative effect on overall survival (Ptrend = 3.80 × 10−12 and 2.48 × 10−7 for MGH and Norwegian cohorts, respectively).

Conclusion Five SNPs were identified that may be prognostic of overall survival in early-stage NSCLC.