Calcium dependent and independent cytokine synthesis by air pollution particle-exposed human bronchial epithelial cells.
Exposure to ambient air pollution particles with a diameter of <10 microm (PM(10)) has been associated with increased cardiopulmonary morbidity and mortality. We have shown that human bronchial epithelial cells (HBECs) exposed to PM(10) produce pro-inflammatory mediators that contribute to a local and systemic inflammatory response. Changes in intracellular calcium concentrations ([Ca(2+)](i)) have been demonstrated to regulate several functions of the airway epithelium including the production of pro-inflammatory mediators. The aim of the present study was to determine the nature and mechanism of calcium responses induced by PM(10) in HBECs and its relationship to cytokine synthesis.


METHODS
Primary HBECs were exposed to urban air pollution particles (EHC-93) and [Ca(2+)](i) responses were measured using the fluoroprobe (Fura-2). Cytokine levels were measured at mRNA and protein levels using real-time PCR and ELISA.


RESULTS
PM(10) increased [Ca(2+)](i) in a dose-dependent manner. This calcium response was reduced by blocking the influx of calcium into cells (i.e. calcium-free medium, NiCl(2), LaCl(3)). PM(10) also decreased the activity of calcium pumps. PM(10) increased the production of IL-1beta, IL-8, GM-CSF and LIF. Preincubation with intracellular calcium chelator (BAPTA-AM) attenuated IL-1beta and IL-8 production, but not GM-CSF and LIF production.


CONCLUSIONS
We conclude that exposure to PM(10) induces an increase in cytosolic calcium and cytokine production in bronchial epithelial cells. Our results also suggest that PM(10) induces the production of pro-inflammatory mediators via either intracellular calcium-dependent (IL-1beta, IL-8) or -independent (GM-CSF, LIF) pathways.
Sakamoto
Noriho
N
James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia, St. Paul's Hospital, Vancouver, BC, Canada.
Hayashi
Shizu
S
Gosselink
John
J
Ishii
Hiroshi
H
Ishimatsu
Yuji
Y
Mukae
Hiroshi
H
Hogg
James C
JC
van Eeden
Stephan F
SF
D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity*; D001980:Bronchi / Q000166:cytology / Q000276:immunology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000187:drug effects*; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology; D005456:Fluorescent Dyes; D016257:Fura-2; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000187:drug effects; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000187:drug effects; D016209:Interleukin-8 / Q000096:biosynthesis / Q000187:drug effects; D053605:Leukemia Inhibitory Factor / Q000096:biosynthesis / Q000187:drug effects; D008875:Middle Aged; D010316:Particle Size; D016133:Polymerase Chain Reaction
D000393:Air Pollutants; D016207:Cytokines; D005456:Fluorescent Dyes; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D016209:Interleukin-8; D053605:Leukemia Inhibitory Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D002118:Calcium; D016257:Fura-2