[HTML][HTML] Spred-2 deficiency exacerbates lipopolysaccharide-induced acute lung inflammation in mice

Y Xu, T Ito, S Fushimi, S Takahashi, J Itakura… - PloS one, 2014 - journals.plos.org
Y Xu, T Ito, S Fushimi, S Takahashi, J Itakura, R Kimura, M Sato, M Mino, A Yoshimura
PloS one, 2014journals.plos.org
Background Acute respiratory distress syndrome (ARDS) is a severe and life-threatening
acute lung injury (ALI) that is caused by noxious stimuli and pathogens. ALI is characterized
by marked acute inflammation with elevated alveolar cytokine levels. Mitogen-activated
protein kinase (MAPK) pathways are involved in cytokine production, but the mechanisms
that regulate these pathways remain poorly characterized. Here, we focused on the role of
Sprouty-related EVH1-domain-containing protein (Spred)-2, a negative regulator of the Ras …
Background
Acute respiratory distress syndrome (ARDS) is a severe and life-threatening acute lung injury (ALI) that is caused by noxious stimuli and pathogens. ALI is characterized by marked acute inflammation with elevated alveolar cytokine levels. Mitogen-activated protein kinase (MAPK) pathways are involved in cytokine production, but the mechanisms that regulate these pathways remain poorly characterized. Here, we focused on the role of Sprouty-related EVH1-domain-containing protein (Spred)-2, a negative regulator of the Ras-Raf-extracellular signal-regulated kinase (ERK)-MAPK pathway, in lipopolysaccharide (LPS)-induced acute lung inflammation.
Methods
Wild-type (WT) mice and Spred-2−/− mice were exposed to intratracheal LPS (50 µg in 50 µL PBS) to induce pulmonary inflammation. After LPS-injection, the lungs were harvested to assess leukocyte infiltration, cytokine and chemokine production, ERK-MAPK activation and immunopathology. For ex vivo experiments, alveolar macrophages were harvested from untreated WT and Spred-2−/− mice and stimulated with LPS. In in vitro experiments, specific knock down of Spred-2 by siRNA or overexpression of Spred-2 by transfection with a plasmid encoding the Spred-2 sense sequence was introduced into murine RAW264.7 macrophage cells or MLE-12 lung epithelial cells.
Results
LPS-induced acute lung inflammation was significantly exacerbated in Spred-2−/− mice compared with WT mice, as indicated by the numbers of infiltrating leukocytes, levels of alveolar TNF-α, CXCL2 and CCL2 in a later phase, and lung pathology. U0126, a selective MEK/ERK inhibitor, reduced the augmented LPS-induced inflammation in Spred-2−/− mice. Specific knock down of Spred-2 augmented LPS-induced cytokine and chemokine responses in RAW264.7 cells and MLE-12 cells, whereas Spred-2 overexpression decreased this response in RAW264.7 cells.
Conclusions
The ERK-MAPK pathway is involved in LPS-induced acute lung inflammation. Spred-2 controls the development of LPS-induced lung inflammation by negatively regulating the ERK-MAPK pathway. Thus, Spred-2 may represent a therapeutic target for the treatment of ALI.
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