Difference in interleukin-8 transcriptional activity induced in THP-G8 cells by particulate matter collected in winter and summer in western Japan

Background : Airborne particulate matter (PM) may stimulate production of pro-inflammatory cytokines, and thus exposure to PM affects pulmonary diseases. However, the effects of PM on pulmonary diseases have differed among studies. Methods : PM was collected from February 2 to 28 (winter) and June 1 to 17 (summer) in 2013 in Yurihama, Japan, using filters to separate particles with different aerodynamic diameters (1.1 to< 2.2 μm, 2.2 to< 3.3 μm, 3.3 to< 7.0 μm, and 7.0 to< 10 μm). Interleukin (IL)-8 transcriptional activity in THP-G8 cells was examined in response to winter and summer PM with different diameters. Results : IL-8 transcriptional activity induced by winter PM was significantly higher than that with summer PM for each diameter. For winter PM, IL-8 activity increased with an increased diameter, whereas this activity did not differ between a solvent control and each summer PM diameter. This indicates that summer PM does not stimulate production of IL-8 in THP-G8 cells. Conclusion : The effects of PM on production of pro-inflammatory cytokines differ with the season and PM diameter. This suggests that the compositions of PM differ on season, and the evaluation of compositions of PM is important in understanding the association of health with short-term exposure to PM.