Innate immune activation by inhaled lipopolysaccharide, independent of oxidative stress, exacerbates silica-induced pulmonary fibrosis in mice.

Abstract

Acute exacerbations of pulmonary fibrosis are characterized by rapid decrements in lung function. Environmental factors that may contribute to acute exacerbations remain poorly understood. We have previously demonstrated that exposure to inhaled lipopolysaccharide (LPS) induces expression of genes associated with fibrosis. To address whether exposure to LPS could exacerbate fibrosis, we exposed male C57BL/6 mice to crystalline silica, or vehicle, followed 28 days later by LPS or saline inhalation. We observed that mice receiving both silica and LPS had significantly more total inflammatory cells, more whole lung lavage MCP-1, MIP-2, KC and IL-1β, more evidence of oxidative stress and more total lung hydroxyproline than mice receiving either LPS alone, or silica alone. Blocking oxidative stress with N-acetylcysteine attenuated whole lung inflammation but had no effect on total lung hydroxyproline. These observations suggest that exposure to innate immune stimuli, such as LPS in the environment, may exacerbate stable pulmonary fibrosis via mechanisms that are independent of inflammation and oxidative stress.

• Authors: David M Brass, Jennifer C Spencer, Zhuowei Li, Erin Potts-Kant, Sarah M Reilly, Mary K Dunkel, Joseph D Latoche, Richard L Auten, John W Hollingsworth, Cheryl L Fattman
• Journal: PloS one (PLoS One) Vol. 7 Issue 7 Pg. e40789 ( 2012) ISSN: 1932-6203 [Electronic] United States
• PMID: 22815821 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Retracted Publication)

Chemical References

• Cytokines
• Drinking Water
• Lipopolysaccharides
• Silicon Dioxide
• Hydroxyproline
• Acetylcysteine

Topics

• Acetylcysteine (pharmacology)
• Administration, Inhalation
• Animals
• Bronchoalveolar Lavage
• Cytokines (metabolism)
• Drinking Water
• Hydroxyproline (metabolism)
• Immunity, Innate (drug effects)
• Inflammation (pathology)
• Lipopolysaccharides (administration & dosage, pharmacology)
• Lung (immunology, metabolism, pathology)
• Male
• Mice
• Mice, Inbred C57BL
• Oxidative Stress (drug effects)
• Protein Carbonylation (drug effects)
• Pulmonary Fibrosis (chemically induced, immunology, pathology)
• Silicon Dioxide