Identification of an ATP/P2X7/mast cell pathway mediating ozone-induced bronchial hyperresponsiveness
Xiaomei Kong, … , Samir N.P. Kelada, Stephen L. Tilley
Xiaomei Kong, … , Samir N.P. Kelada, Stephen L. Tilley
Published September 21, 2021
Citation Information: JCI Insight. 2021;6(21):e140207. https://doi.org/10.1172/jci.insight.140207.
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Research Article Cell biology Immunology

Identification of an ATP/P2X7/mast cell pathway mediating ozone-induced bronchial hyperresponsiveness

Abstract

Ozone is a highly reactive environmental pollutant with well-recognized adverse effects on lung health. Bronchial hyperresponsiveness (BHR) is one consequence of ozone exposure, particularly for individuals with underlying lung disease. Our data demonstrated that ozone induced substantial ATP release from human airway epithelia in vitro and into the airways of mice in vivo and that ATP served as a potent inducer of mast cell degranulation and BHR, acting through P2X7 receptors on mast cells. Both mast cell–deficient and P2X7 receptor–deficient (P2X7–/–) mice demonstrated markedly attenuated BHR to ozone. Reconstitution of mast cell–deficient mice with WT mast cells and P2X7–/– mast cells restored ozone-induced BHR. Despite equal numbers of mast cells in reconstituted mouse lungs, mice reconstituted with P2X7–/– mast cells demonstrated significantly less robust BHR than mice reconstituted with WT mast cells. These results support a model where P2X7 on mast cells and other cell types contribute to ozone-induced BHR.

Authors

Xiaomei Kong, William C. Bennett, Corey M. Jania, Kelly D. Chason, Zachary German, Jennifer Adouli, Samuel D. Budney, Brandon T. Oby, Catharina van Heusden, Eduardo R. Lazarowski, Ilona Jaspers, Scott H. Randell, Barry A. Hedgespeth, Glenn Cruse, Xiaoyang Hua, Stephen A. Schworer, Gregory J. Smith, Samir N.P. Kelada, Stephen L. Tilley

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Figure 2

Mast cells mediate ozone-induced BHR, but ozone does not directly activate mast cells.

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Mast cells mediate ozone-induced BHR, but ozone does not directly activa...
(A) Ozone-induced BHR is mast cell dependent. C57BL/6 WT and C57BL/6KitW-sh/W-sh mast cell–deficient mice (females, aged 12–30 weeks) were exposed to 2 ppm ozone or air for 3 hours and challenged with methacholine at 24 hours. Yellow circles represent air-treated WT mice (n = 3), blue circles represent ozone-treated WT mice (n = 14), yellow squares represent air-treated mast cell–deficient mice (n = 3), and blue squares represent ozone-treated mast cell–deficient mice (n = 14); *P < 0.05 by mixed effects analysis comparing repeated measures between WT and WSH ozone exposures. (B) Ozone activates airway mast cells. WT mice (females, aged 10–16 weeks) were exposed to 2 ppm ozone or air for 3 hours and BALF was collected immediately after exposure. Histamine concentrations were measured by ELISA. Yellow circles represent histamine concentrations in BALF from air-treated mice and blue circles represent the same in ozone-treated mice. n = 7–8; *P < 0.05 by Student’s t test. (C) Graphic depicting HBE-ALI/mast cell coculture. (D) Ozone indirectly activates mast cells in HBE/mast cell cocultures. Primary HBE cells grown for 21 days under ALI conditions were cocultured with CBMCs and exposed to 0.8 ppm ozone or air for 4 hours at 37°C and 5% CO2. Histamine concentrations were measured by ELISA in basolateral media collected immediately after exposure. Yellow circles represent air-treated cells and blue circles represent ozone-treated cells. n = 5, *P < 0.05 by Student’s t test. Data are shown as mean ± SEM.