title: Endotoxin in concentrated coarse and fine ambient particles induces acute systemic inflammation in controlled human exposures.
abstract: BACKGROUND
  Knowledge of the inhalable particulate matter components responsible for health effects is important for developing targeted regulation.
  
  
  OBJECTIVE
  In a double-blind randomised cross-over trial of controlled human exposures to concentrated ambient particles (CAPs) and their endotoxin and (1→3)-β-D-glucan components, we evaluated acute inflammatory responses.
  
  
  METHODS
  35 healthy adults were exposed to five 130-min exposures at rest: (1) fine CAPs (~250 µg/m(3)); (2) coarse CAPs (200 µg/m(3)); (3) second coarse CAPs (~200 µg/m(3)); (4) filtered air; and (5) medical air. Induced sputum cell counts were measured at screening and 24 h postexposure. Venous blood total leucocytes, neutrophils, interleukin-6 and high-sensitivity C reactive protein (CRP) were measured pre-exposure, 3 and 24 h postexposure.
  
  
  RESULTS
  Relative to filtered air, an increase in blood leucocytes 24 h (but not 3 h) postexposure was significantly associated with coarse (estimate=0.44×10(9) cells/L (95% CI 0.01 to 0.88); n=132) and fine CAPs (0.68×10(9) cells /L (95% CI 0.19 to 1.17); n=132), but not medical air. Similar associations were found with neutrophil responses. An interquartile increase in endotoxin (5.4 ng/m(3)) was significantly associated with increased blood leucocytes 3 h postexposure (0.27×10(9) cells/L (95% CI 0.03 to 0.51); n=98) and 24 h postexposure (0.37×10(9) cells/L (95% CI 0.12 to 0.63); n=98). This endotoxin effect did not differ by particle size. There were no associations with glucan concentrations or interleukin-6, CRP or sputum responses.
  
  
  CONCLUSIONS
  In healthy adults, controlled coarse and fine ambient particle exposures independently induced acute systemic inflammatory responses. Endotoxin contributes to the inflammatory role of particle air pollution.
authors.affiliation: Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
authors.forename: Behrooz
authors.initials: B
authors.lastname: Behbod
authors.forename: Bruce
authors.initials: B
authors.lastname: Urch
authors.forename: Mary
authors.initials: M
authors.lastname: Speck
authors.forename: James A
authors.initials: JA
authors.lastname: Scott
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.forename: Raymond
authors.initials: R
authors.lastname: Poon
authors.forename: Brent
authors.initials: B
authors.lastname: Coull
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Petros
authors.initials: P
authors.lastname: Koutrakis
authors.forename: Frances
authors.initials: F
authors.lastname: Silverman
authors.forename: Diane R
authors.initials: DR
authors.lastname: Gold
mesh_terms: D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology; D004311:Double-Blind Method; D004731:Endotoxins / Q000009:adverse effects* / Q000276:immunology; D005260:Female; D006801:Humans; D007249:Inflammation / Q000139:chemically induced*; D019570:Inhalation Exposure / Q000009:adverse effects*; D007962:Leukocytes / Q000378:metabolism*; D008297:Male; D009504:Neutrophils / Q000378:metabolism; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D004731:Endotoxins; D052638:Particulate Matter