Baseline repeated measures from controlled human exposure studies: associations between ambient air pollution exposure and the systemic inflammatory biomarkers IL-6 and fibrinogen

Environ Health Perspect. 2010 Jan;118(1):120-4. doi: 10.1289/ehp.0900550.

Abstract

Introduction: Systemic inflammation may be one of the mechanisms mediating the association between ambient air pollution and cardiovascular morbidity and mortality. Interleukin-6 (IL-6) and fibrinogen are biomarkers of systemic inflammation that are independent risk factors for cardio-vascular disease.

Objective: We investigated the association between ambient air pollution and systemic inflammation using baseline measurements of IL-6 and fibrinogen from controlled human exposure studies.

Methods: In this retrospective analysis we used repeated-measures data in 45 nonsmoking subjects. Hourly and daily moving averages were calculated for ozone, nitrogen dioxide, sulfur dioxide, and particulate matter <or= 2.5 microm in aerodynamic diameter (PM2.5). Linear mixed-model regression determined the effects of the pollutants on systemic IL-6 and fibrinogen. Effect modification by season was considered.

Results: We observed a positive association between IL-6 and O3 [0.31 SD per O3 interquartile range (IQR); 95% confidence interval (CI), 0.080.54] and between IL-6 and SO2 (0.25 SD per SO2 IQR; 95% CI, 0.060.43). We observed the strongest effects using 4-day moving averages. Responses to pollutants varied by season and tended to be higher in the summer, particularly for O3 and PM2.5. Fibrinogen was not associated with pollution.

Conclusions: This study demonstrates a significant association between ambient pollutant levels and baseline levels of systemic IL-6. These findings have potential implications for controlled human exposure studies. Future research should consider whether ambient pollution exposure before chamber exposure modifies IL-6 response.

MeSH terms

  • Adult
  • Air Pollution / adverse effects*
  • Air Pollution / analysis
  • Biomarkers / blood
  • Environmental Exposure
  • Female
  • Fibrinogen / metabolism*
  • Humans
  • Inflammation Mediators / blood
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Regression Analysis
  • Retrospective Studies
  • Seasons
  • Young Adult

Substances

  • Biomarkers
  • IL6 protein, human
  • Inflammation Mediators
  • Interleukin-6
  • Fibrinogen