P2X7 receptor modulates inflammatory and functional pulmonary changes induced by silica

• Published in: PloS one Vol. 9; no. 10; p. e110185
• Main Authors: Monção-Ribeiro, Leonardo C, Faffe, Débora S, Santana, Patrícia T, Vieira, Flávia S, da Graça, Carolyne Lalucha A L, Marques-da-Silva, Camila, Machado, Mariana N, Caruso-Neves, Celso, Zin, Walter A, Borojevic, Radovan, Takiya, Christina M, Coutinho-Silva, Robson
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.10.2014; Public Library of Science (PLoS)
• Subjects: Alveoli; Analysis; Animal models; Animals; Apoptosis; Biology and Life Sciences; Bronchoalveolar lavage; Bronchoalveolar Lavage Fluid; Bronchus; Collagen; Collagen - metabolism; Cytokines; Cytometry; Disease; Exposure; Fibers; Fibroblasts; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibrosis; Flow cytometry; IL-1β; Immunophenotyping; Infiltration; Inflammation; Inflammation - metabolism; Inflammation - pathology; Inflation (Economics); Interleukin-1beta - metabolism; Laboratory animals; Lung - metabolism; Lung - pathology; Lung - physiopathology; Lung diseases; Lungs; Macrophages; Macrophages, Alveolar - drug effects; Macrophages, Alveolar - metabolism; Mechanical properties; Mechanics; Mice; Mice, Inbred C57BL; NF-kappa B - metabolism; NF-κB protein; NIH 3T3 Cells; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide Synthase Type II - metabolism; Occlusion; Occupational diseases; Occupational exposure; Oxidative stress; Oxygen; Oxygen production; Parenchyma; Peritoneum; Phagocytosis; Phagocytosis - drug effects; Physiology; Pressure transducers; Pulmonary Fibrosis - pathology; Pulmonary Fibrosis - physiopathology; Purinergic P2X Receptor Antagonists - pharmacology; Reactive oxygen species; Reactive Oxygen Species - metabolism; Receptors, Purinergic P2X7 - metabolism; Rodents; Rosaniline Dyes - metabolism; Signal Transduction - drug effects; Silica; Silicon dioxide; Silicon Dioxide - toxicity; Silicosis; Smad2 Protein - metabolism; Smad3 Protein - metabolism; Trachea; Transforming Growth Factor beta - metabolism; Transforming growth factors; Tumor necrosis factor-TNF; Brazil; United States > US; Rio de Janeiro Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0110185

Silicosis is an occupational lung disease, characterized by irreversible and progressive fibrosis. Silica exposure leads to intense lung inflammation, reactive oxygen production, and extracellular ATP (eATP) release by macrophages. The P2X7 purinergic receptor is thought to be an important immunomodulator that responds to eATP in sites of inflammation and tissue damage. The present study investigates the role of P2X7 receptor in a murine model of silicosis. To that end wild-type (C57BL/6) and P2X7 receptor knockout mice received intratracheal injection of saline or silica particles. After 14 days, changes in lung mechanics were determined by the end-inflation occlusion method. Bronchoalveolar lavage and flow cytometry analyzes were performed. Lungs were harvested for histological and immunochemistry analysis of fibers content, inflammatory infiltration, apoptosis, as well as cytokine and oxidative stress expression. Silica particle effects on lung alveolar macrophages and fibroblasts were also evaluated in cell line cultures. Phagocytosis assay was performed in peritoneal macrophages. Silica exposure increased lung mechanical parameters in wild-type but not in P2X7 knockout mice. Inflammatory cell infiltration and collagen deposition in lung parenchyma, apoptosis, TGF-β and NF-κB activation, as well as nitric oxide, reactive oxygen species (ROS) and IL-1β secretion were higher in wild-type than knockout silica-exposed mice. In vitro studies suggested that P2X7 receptor participates in silica particle phagocytosis, IL-1β secretion, as well as reactive oxygen species and nitric oxide production. In conclusion, our data showed a significant role for P2X7 receptor in silica-induced lung changes, modulating lung inflammatory, fibrotic, and functional changes.