Inflammatory response to fine particulate air pollution exposure: neutrophil versus monocyte.
OBJECTIVE
Studies have shown that chronic exposure to ambient fine particulate matter (less than 2.5 µm in aerodynamic diameter, PM₂.₅) pollution induces insulin resistance through alterations in inflammatory pathways. It is critical to study how the immune system responds to this stimulant, which has been linked to cardiovascular and autoimmune diseases, but few studies have been focused on such involvement of both neutrophils and monocytes in a timely manner. We hypothesized that the neutrophil was involved in the inflammatory response to air pollution.


RESULTS
C57BL/6 mice were exposed to PM₂.₅ or filtered air (6 hours/day, 5 days/week) for 5, 14, and 21 days, respectively, in Columbus, OH. At the end of each of the exposure periods, we investigated the inflammatory response through flow cytometry, histology, intravital microscopy, and real-time PCR. PM₂.₅-exposed mice demonstrated a significant inflammatory response after 5 days of exposure. In the lung tissue and bronchoalveolar lavage fluid, monocytes/macrophages showed a transient response, while neutrophils showed a cumulative response. In addition, exposure to PM₂.₅ resulted in elevation of the monocyte chemoattractant protein 1 (MCP-1) cytokine, a monocyte/macrophage attractant in blood, at an early stage of exposure.


CONCLUSIONS
These findings suggest that PM₂.₅ exposure induces the inflammatory responses from both macrophages and neutrophils involvement.
Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America.
Xiaohua
X
Xu
Silis Y
SY
Jiang
Tse-Yao
TY
Wang
Yuntao
Y
Bai
Mianhua
M
Zhong
Aixia
A
Wang
Morton
M
Lippmann
Lung-Chi
LC
Chen
Sanjay
S
Rajagopalan
Qinghua
Q
Sun
D000397:Air Pollution / Q000009:adverse effects*; D000818:Animals; D002634:Chemotaxis, Leukocyte; D007249:Inflammation / Q000209:etiology* / Q000276:immunology / Q000473:pathology; D019570:Inhalation Exposure / Q000009:adverse effects*; D008168:Lung / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D009504:Neutrophils / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D052638:Particulate Matter / Q000009:adverse effects* / Q000276:immunology
D052638:Particulate Matter