Elsevier

Environment International

Volume 113, April 2018, Pages 26-34
Environment International

The human circulating miRNome reflects multiple organ disease risks in association with short-term exposure to traffic-related air pollution

https://doi.org/10.1016/j.envint.2018.01.014Get rights and content

Highlights

  • Analysis of circulating miRNAs in a human population exposed to traffic pollution.

  • The study revealed 54 miRNAs that were affected already after 2 h of exposure.

  • These miRNAs are involved in the molecular processes of exposure-related diseases.

  • This study highlights circulating miRNA profiles as promising sensitive biomarkers.

Abstract

Traffic-related air pollution is a complex mixture of particulate matter (PM) and gaseous pollutants, such as nitrogen dioxide (NO2). PM exposure contributes to the pathogenesis of many diseases including several types of cancer, as well as pulmonary, cardiovascular and neurodegenerative diseases. Also exposure to NO2 has been related to increased cardiovascular mortality. In search of an early diagnostic biomarker for improved air pollution-associated health risk assessment, recent human studies have shown that certain circulating miRNAs are altered upon exposure to traffic-related air pollutants. Here, we present for the first time a global analysis of the circulating miRNA genome in an experimental cross-over study of a human population exposed to traffic-related air pollution. By utilizing next-generation sequencing technology and detailed real-time exposure measurements we identified 54 circulating miRNAs to be dose- and pollutant species-dependently associated with PM10, PM2.5, black carbon, ultrafine particles and NO2 already after 2 h of exposure. Bioinformatics analysis suggests that these circulating miRNAs actually reflect the adverse consequences of traffic pollution-induced toxicity in target tissues including the lung, heart, kidney and brain. This study shows the strong potential of circulating miRNAs as novel biomarkers for environmental health risk assessment.

Introduction

Numerous epidemiological studies have associated exposure to traffic-related air pollution (TRAP) with increased risk of cardiovascular disease, (Brook et al., 2010; Lee et al., 2014) respiratory disease, (Xing et al., 2016) several types of cancer, including lung and breast cancer, (Hamra et al., 2014; Tagliabue et al., 2016) and more recently also of neurodegenerative diseases (Cacciottolo et al., 2017; Chen et al., 2017) and kidney disease (Bowe et al., 2017). A number of gaseous pollutants such as nitrogen dioxide (NO2) as well as particulate matter components (PM) are routinely monitored to characterize TRAP exposure. PM is a complex mixture of fine particles with a diameter of 10 μm or less (PM10), a diameter of 2.5 μm or less (PM2.5), black carbon (BC), ultrafine particles with a diameter of 0.1 μm or less (UFP) and soot (Falcon-Rodriguez et al., 2016). Upon inhalation PM penetrates deeply into the lungs from where, depending on their size, particles are capable of entering the circulation and being distributed to distal organs such as the heart, spleen or liver (Falcon-Rodriguez et al., 2016; Li et al., 2015; Yaghjyan et al., 2017). It has even been reported that ultrafine PM crosses the blood-brain barrier and translocates from the circulation to the brain (Oberdorster et al., 2004). Further, it has been demonstrated that PM triggers oxidative stress in the respiratory tract and that this might induce a systemic inflammatory cascade, thus increasing the risk for respiratory and cardiovascular diseases (Bollati et al., 2015). Presumably, pollutants, once distributed over the whole body, may cause a similar cascade of oxidative stress and inflammation in target organs, thereby increasing risks for cancer and neurodegenerative disease (Block & Calderon-Garciduenas, 2009). However, the precise molecular mechanisms that link TRAP exposure to increased disease risks are still poorly understood which hampers the development of dedicated biomarkers capable of informing on relevant molecular mechanisms of action.

Several studies have thus highlighted the impact of environmental exposure on gene expression profiles, (van Leeuwen et al., 2006) DNA-methylation patterns, (Georgiadis et al., 2016) and p53 status (Intarasunanont et al., 2012). More recently, environmental exposure-induced alterations in microRNA (miRNA) levels have been described (Krauskopf et al., 2017a). These small non-coding RNAs are involved in the posttranscriptional regulation of gene expression, and consequently are involved in virtually all cellular processes (Bartel, 2009). Furthermore, while these fine-tuners of gene expression are capable of adjusting to internal and external conditions, they also exhibit tissue/organ specific expression patterns (Landgraf et al., 2007). As a consequence of organ injury, cells may leak their content including the highly stable protein-bound miRNAs, into the peripheral circulation (Turchinovich et al., 2012). Given the fact that certain miRNAs are more abundantly expressed in specific organs, circulating miRNA (cmiRNA) signatures may thus also reflect organ-specific responses to exposure (Krauskopf et al., 2015). Furthermore, through active secretion, extracellular vesicle-bound cmiRNAs may act as mediators in intercellular and interorgan communication (Hunter et al., 2008). Therefore, cmiRNAs leaked or released from organs into the circulation, have become a new promising class of biomarkers capable of non-invasively interrogating organ pathogenesis and organ-toxic mechanisms from so called ‘liquid biopsies’ (Krauskopf et al., 2015).

To date, most reported air pollution-induced changes in miRNA expression have been identified in solid tissues in animal models (Vrijens et al., 2015). The first evidence on PM exposure-related modifications in cmiRNA levels in humans was provided through investigating healthy steel plant workers. This study identified 2 vesicle-associated miRNAs that were elevated after occupational exposure to metal-rich PM (Bollati et al., 2015). Additionally, a study on long term exposure to ambient air pollution (6 month or 1 year) identified the elevation of 5 vesicle-associated cmiRNAs in the serum of healthy subjects (Rodosthenous et al., 2016). Another study among children identified 2 cmiRNAs in the extracellular fraction of saliva to be significantly altered with long-term ultrafine PM exposure (Vriens et al., 2016).

These studies provided evidence that the extracellular miRNA genome (miRNome) is affected by TRAP exposure through utilizing targeted approaches, and were consequently restricted to analyzing a priori known air pollution-associated miRNAs. In the current study, we present for the first time a global analysis of the circulating miRNome by applying next generation sequencing technology and real-time exposure measurements in an experimental cross-over study of human volunteers (n = 24) following short-term traffic-related air pollution exposure. This study demonstrates the potential of circulating miRNAs as novel biomarkers for health risk assessment in relation to environmental exposure-induced target tissue pathogenesis.

Section snippets

Selection of the population

Plasma samples were collected during a randomized experimental crossover study in which non-smoking participants, either healthy or suffering from ischemic heart disease (IHD) or chronic obstructive pulmonary disease (COPD), walked for 2 h along Oxford Street in London (where only diesel-powered buses and taxicabs are permitted). In a separate session the same subjects also walked for 2 h through traffic-free Hyde Park. In order to balance between sufficient exposure and what is acceptable for

Exposure range

The subjects analyzed for cmiRNAs were exposed to a mean ambient air NO2 level of 7.9 (CI 5.9–9.8) μg/m3 in Hyde Park and 18.1 (CI 15.1–21.1) μg/m3 in Oxford Street. For PM2.5 the mean exposure level in Hyde Park was 5.6 (CI 4.5–6.8) μg/m3 and 25.6 (CI 21–30.2) μg/m3 in Oxford Street. For BC the exposure level was 1.0 (CI 0.8–1.3) μg/m3 in Hyde Park and 11.4 (CI 9.9–12.8) μg/m3 in Oxford Street and for PM10 16.0 (CI 12.5–19.5) μg/m3 in Hyde Park and 37.0 (CI 32.2–41.7) μg/m3 in Oxford Street.

Discussion

In this study, we evaluated the global circulating miRNome in plasma from human subjects exposed to ambient TRAP for only 2 h by using NGS. We identified 54 cmiRNAs that appear to be involved in the molecular response to NO2, UFP, PM2.5, BC and PM10 exposure. Next, we gathered information on tissue-specific miRNAs from those organs known to be targeted by ambient air pollutants. We found that the most abundant cmiRNAs present in plasma are equally expressed in all organs known to be targeted by

Author contributions

J.K., T.M.K. and J.C.K. designed the research. K.F.C., P. Cu., P. Co., B.B., F.J.K. and P.V. organized the epidemiologic part of the work. J.K. and R.S. performed the experiments. J.K., F.C., K.V., M.C. and R.V. analyzed the data. T.M.K. and J.C.K. supervised the project. J.K., T.M.K. and J.C.K. co-wrote and all authors commented on the paper.

Additional information

The authors declare no competing financial interests.

Acknowledgments

This work has been supported by the European Union within the frame of the Exposomics (226756) project and the British Heart Foundation (PGF/10/82/28608).

References (71)

  • G. Serino

    In a retrospective international study, circulating miR-148b and let-7b were found to be serum markers for detecting primary IgA nephropathy

    Kidney Int.

    (2016)
  • A. Turchinovich et al.

    Extracellular miRNAs: the mystery of their origin and function

    Trends Biochem. Sci.

    (2012)
  • D.M. van Leeuwen

    Genome-wide differential gene expression in children exposed to air pollution in the Czech Republic

    Mutat. Res.

    (2006)
  • G. Wang

    Variation in the miRNA-433 binding site of FGF20 confers risk for Parkinson disease by overexpression of alpha-synuclein

    Am. J. Hum. Genet.

    (2008)
  • A.S. Baras

    miRge - A Multiplexed Method of Processing Small RNA-Seq Data to Determine MicroRNA Entropy

    PLoS One

    (2015)
  • D. Bates et al.

    Fitting linear mixed-effects models using lme4

    J. Stat. Softw.

    (2015)
  • Y. Benjamini et al.

    Controlling the false discovery rate - a practical and powerful approach to multiple testing

    J. Roy. Stat. Soc. B Met.

    (1995)
  • P. Bhat-Nakshatri

    Estradiol-regulated microRNAs control estradiol response in breast cancer cells

    Nucleic Acids Res.

    (2009)
  • V. Bollati

    Microvesicle-associated microRNA expression is altered upon particulate matter exposure in healthy workers and in A549 cells

    J. Appl. Toxicol.

    (2015)
  • B. Bowe

    Particulate matter air pollution and the risk of incident CKD and progression to ESRD

    J. Am. Soc. Nephrol.

    (2017)
  • R.D. Brook

    Particulate matter air pollution and cardiovascular disease: an update to the scientific statement from the American Heart Association

    Circulation

    (2010)
  • K. Burgos

    Profiles of extracellular miRNA in cerebrospinal fluid and serum from patients with Alzheimer's and Parkinson's diseases correlate with disease status and features of pathology

    PLoS One

    (2014)
  • M. Cacciottolo

    Particulate air pollutants, APOE alleles and their contributions to cognitive impairment in older women and to amyloidogenesis in experimental models

    Transl. Psychiatry

    (2017)
  • A. Care

    MicroRNA-133 controls cardiac hypertrophy

    Nat. Med.

    (2007)
  • Z. Chen

    miRNA-145 inhibits non-small cell lung cancer cell proliferation by targeting c-Myc

    J. Exp. Clin. Cancer Res.

    (2010)
  • D.M. Cittelly

    Downregulation of miR-342 is associated with tamoxifen resistant breast tumors

    Mol. Cancer

    (2010)
  • M.A. Faghihi

    Evidence for natural antisense transcript-mediated inhibition of microRNA function

    Genome Biol.

    (2010)
  • C.I. Falcon-Rodriguez et al.

    Aeroparticles, Composition, and Lung Diseases

    Front. Immunol.

    (2016)
  • N. Garbacki

    MicroRNAs Profiling in murine models of acute and chronic asthma: a relationship with mRNAs targets

    PLoS One

    (2011)
  • P. Georgiadis

    Omics for prediction of environmental health effects: blood leukocyte-based cross-omic profiling reliably predicts diseases associated with tobacco smoking

    Sci. Rep.

    (2016)
  • S. Griffiths-Jones et al.

    miRBase: microRNA sequences, targets and gene nomenclature

    Nucleic Acids Res.

    (2006)
  • G.B. Hamra

    Outdoor particulate matter exposure and lung cancer: a systematic review and meta-analysis

    Environ. Health Perspect.

    (2014)
  • A.G. Hoss et al.

    microRNA profiles in Parkinson's disease prefrontal cortex

    Front. Aging Neurosci.

    (2016)
  • M.P. Hunter

    Detection of microRNA expression in human peripheral blood microvesicles

    PLoS One

    (2008)
  • P. Intarasunanont

    Effects of arsenic exposure on DNA methylation in cord blood samples from newborn babies and in a human lymphoblast cell line

    Environ. Health

    (2012)
  • Cited by (0)

    View full text