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 4

ATP activates mast cells and induces BHR.

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ATP activates mast cells and induces BHR. (A) ATP induces murine airway ...
(A) ATP induces murine airway mast cell degranulation. WT mice (females, aged 9–25 weeks) were exposed to aerosolized ATP (50 mg/mL) or PBS; BALF collected after 30 minutes for histamine analysis. Black and red circles represent histamine levels from PBS- and ATP-treated mice, respectively. n = 3; *P < 0.05 by Student’s t test. (B) ATP-induced BHR is mast cell dependent. C57BL/6 WT and C57BL/6KitW-sh/W-sh mast cell–deficient mice (females, aged 9–25 weeks) were exposed to aerosolized ATP (50 mg/mL), then methacholine 30 minutes later. Black and red circles represent PBS-treated (n = 4) and ATP-treated WT mice (n = 16), respectively; black and red squares represent PBS-treated (n = 3) and ATP-treated mast cell–deficient mice (n = 8), respectively; *P < 0.05 by mixed effects analysis between ATP-treated groups. (C and D) ATP induces degranulation in murine BMMCs (C) and human CBMCs (D) in vitro. Mast cells were treated with ATP (300 μM, 1000 μM) or PBS for 30 minutes prior to hexosaminidase measurement. Black and red circles represent PBS- and ATP-treated cells, respectively. n = 4; *P < 0.05 by Student’s t test. (E) ATP potentiates antigen-induced degranulation in CBMCs. CBMCs were incubated for 3 days at 1 × 106 cells/mL at 37°C in medium with 10 ng/mL recombinant human IL-4. Cells were incubated with antagonist (PSB1115) or vehicle (DMSO) for 30 minutes prior to ATP or adenosine addition and centrifuged after 30 minutes, and β-hexosaminidase release was assessed. Red and purple circles represent ATP- and adenosine-treated cells, respectively. n = 4; *P < 0.05 by Student’s t test. (F) ATP but not adenosine induces BHR in A3–/– mice. A3–/– mice (females, aged 9–25 weeks) were exposed to aerosolized ATP (50 mg/mL), adenosine (50 mg/mL), or PBS and then methacholine 30 minutes later. Purple and red triangles represent adenosine-treated (n = 7) and ATP-treated mice (n = 8), respectively. *P < 0.05 by mixed effects analysis. Data are shown as mean ± SEM.