Ozone-induced IL-17A and neutrophilic airway inflammation is orchestrated by the caspase-1-IL-1 cascade

Sci Rep. 2016 Jan 7:6:18680. doi: 10.1038/srep18680.

Abstract

Ozone is a common environmental air pollutant leading to respiratory illness. The mechanisms regulating ozone-induced airway inflammation remain poorly understood. We hypothesize that ozone-triggered inflammasome activation and interleukin (IL)-1 production regulate neutrophilic airway inflammation through IL-17A. Pulmonary neutrophilic inflammation was induced by extended (72 h) low-dose (0.7 ppm) exposure to ozone. IL-1 receptor 1 (Il1r1)(-/-), Il17a(-/-) mice and the caspase-1 inhibitor acetyl-YVAD-chloromethylketone (Ac-YVAD-cmk) were used for in vivo studies. Cellular inflammation and protein levels in bronchial alveolar lavage fluid (BALF), cytokines, and IL-17A-producing γδT-cells, as well as mitochondrial reactive oxygen species (ROS), mitochondrial DNA (mtDNA) release, and inflammasome activation in lung macrophages were analyzed. Ozone-induced neutrophilic airway inflammation, accompanied an increased production of IL-1β, IL-18, IL-17A, Granulocyte-colony stimulating factor (G-CSF), Interferon-γ inducible protein 10 (IP-10) and BALF protein in the lung. Ozone-induced IL-17A production was predominantly in γδT-cells, and Il17a-knockout mice exhibited reduced airway inflammation. Lung macrophages from ozone-exposed mice exhibited higher levels of mitochondrial ROS, enhanced cytosolic mtDNA, increased caspase-1 activation, and higher production of IL-1β. Il1r1-knockout mice or treatment with Ac-YVAD-cmk decreased the IL-17A production and subsequent airway inflammation. Taken together, we demonstrate that ozone-induced IL-17A and neutrophilic airway inflammation is orchestrated by the caspase-1-IL-1 cascade.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caspase 1 / metabolism*
  • Disease Models, Animal
  • Inflammasomes / metabolism
  • Interleukin-1 / metabolism*
  • Interleukin-17 / genetics
  • Interleukin-17 / metabolism*
  • Macrophages, Alveolar / immunology
  • Macrophages, Alveolar / metabolism
  • Mice
  • Mice, Knockout
  • Neutrophils / metabolism*
  • Ozone / adverse effects*
  • Pneumonia / genetics
  • Pneumonia / metabolism*
  • Pneumonia / pathology
  • Receptors, Antigen, T-Cell, gamma-delta / metabolism
  • Signal Transduction
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism

Substances

  • Inflammasomes
  • Interleukin-1
  • Interleukin-17
  • Receptors, Antigen, T-Cell, gamma-delta
  • Ozone
  • Caspase 1