title: Effects of short-term exposure to inhalable particulate matter on telomere length, telomerase expression, and telomerase methylation in steel workers.
abstract: BACKGROUND
  Shortened leukocyte telomere length (LTL) is a marker of cardiovascular risk that has been recently associated with long-term exposure to ambient particulate matter (PM). However, LTL is increased during acute inflammation and allows for rapid proliferation of inflammatory cells. Whether short-term exposure to proinflammatory exposures such as PM increases LTL has never been evaluated.
  
  
  OBJECTIVE
  We investigated the effects of acute exposure to metal-rich PM on blood LTL, as well as molecular mechanisms contributing to LTL regulation in a group of steel workers with high PM exposure.
  
  
  METHODS
  We measured LTL, as well as mRNA expression and promoter DNA methylation of the telomerase catalytic enzyme gene [human telomerase reverse transcriptase (hTERT)] in blood samples obtained from 63 steel workers on the first day of a workweek (baseline) and after 3 days of work (postexposure).
  
  
  RESULTS
  LTL was significantly increased in postexposure (mean ± SD, 1.43 ± 0.51) compared with baseline samples (1.23 ± 0.28, p-value < 0.001). Postexposure LTL was positively associated with PM₁₀ (β = 0.30, p-value = 0.002 for 90th vs. 10th percentile exposure) and PM₁ (β = 0.29, p-value = 0.042) exposure levels in regression models adjusting for multiple covariates. hTERT expression was lower in postexposure samples (1.31 ± 0.75) than at baseline (1.68 ± 0.86, p-value < 0.001), but the decrease in hTERT expression did not show a dose-response relationship with PM. We found no exposure-related differences in the methylation of any of the CpG sites investigated in the hTERT promoter.
  
  
  CONCLUSIONS
  Short-term exposure to PM caused a rapid increase in blood LTL. The LTL increase did not appear to be mediated by PM-related changes in hTERT expression and methylation.
authors.affiliation: Laboratory of Environmental Epigenetics, Department of Preventive Medicine, University of Milan and IRCCS Ca' Granda Maggiore Policlinico Hospital Foundation, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Dioni
authors.forename: Mirjam
authors.initials: M
authors.lastname: Hoxha
authors.forename: Francesco
authors.initials: F
authors.lastname: Nordio
authors.forename: Matteo
authors.initials: M
authors.lastname: Bonzini
authors.forename: Letizia
authors.initials: L
authors.lastname: Tarantini
authors.forename: Benedetta
authors.initials: B
authors.lastname: Albetti
authors.forename: Alice
authors.initials: A
authors.lastname: Savarese
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Pier Alberto
authors.initials: PA
authors.lastname: Bertazzi
authors.forename: Pietro
authors.initials: P
authors.lastname: Apostoli
authors.forename: Lifang
authors.initials: L
authors.lastname: Hou
authors.forename: Andrea
authors.initials: A
authors.lastname: Baccarelli
mesh_terms: D000328:Adult; D006801:Humans; D001239:Inhalation; D008297:Male; D008745:Methylation / Q000187:drug effects; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects; D052638:Particulate Matter / Q000633:toxicity*; D013232:Steel; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000187:drug effects*
chemical_list: D052638:Particulate Matter; D013232:Steel; D019098:Telomerase