ABSTRACT
Exposure to particulate matter (PM) is associated with increased incidence of respiratory diseases. The present study aimed to investigate the roles of fibroblast growth factor 10 (FGF10) in PM-induced lung injury. Mice were intratracheally instilled with FGF10 or phosphate-buffered saline at one hour before instillation of PM for two consecutive days. In addition, the anti-inflammatory impact of FGF10 in vitro and its effect on the high-mobility group box 1 (HMGB1)-toll-like receptor 4 (TLR4) pathway was investigated. It was found that PM exposure is associated with increased inflammatory cell infiltration into the lung and increased vascular protein leakage, while FGF10 pretreatment attenuated both of these effects. FGF10 also decreased the PM-induced expression of interleukin (IL)-6, IL-8, tumor necrosis factor-α and HMGB1 in murine bronchoalveolar lavage fluid and in the supernatants of human bronchial epithelial cells exposed to PM. FGF10 exerted anti-inflammatory and cytoprotective effects by inhibiting the HMGB1-TLR4 pathway. These results indicate that FGF10 may have therapeutic values for PM-induced lung injury.
Subject(s)
Fibroblast Growth Factor 10/metabolism , HMGB1 Protein/metabolism , Lung Injury/etiology , Lung Injury/metabolism , Particulate Matter/adverse effects , Toll-Like Receptor 4/metabolism , Biomarkers , Biopsy , Cell Death , Cytokines/metabolism , Disease Susceptibility , Fibroblast Growth Factor 10/genetics , Gene Expression , Gene Knockdown Techniques , HMGB1 Protein/genetics , Humans , Immunohistochemistry , Lung Injury/pathology , Respiratory Mucosa/metabolism , Respiratory Mucosa/pathology , Signal Transduction , Toll-Like Receptor 4/geneticsABSTRACT
Particulate matter (PM) is an environmental pollutant closely associated with human airway inflammation. However, the molecular mechanisms of PM-related airway inflammation remains to be fully elucidated. It is known that COX-2/PGE2 play key roles in the pathogenesis of airway inflammation. Filaggrin is a transmembrane protein contributing to tight junction barrier function. As such, Filaggrin prevents leakage of transported solutes and is therefore necessary for the maintenance of epithelial integrity. The objective of the present study was to investigate the regulatory mechanisms of COX-2/PGE2 and Filaggrin upon PM exposure both in vivo and in vitro. C57BL/6 mice received intratracheal instillation of PM for two consecutive days. In parallel, human bronchial epithelial cells (HBECs) were exposed to PM for 24 h. PM exposure resulted in airway inflammation together with upregulation of COX-2/PGE2 and downregulation of Filaggrin in mouse lungs. Corresponding dysregulation of COX-2/PGE2 and Filaggrin was also observed in HBECs subjected to PM. PM exposure led to the phosphorylation of ERK, JNK, and PI3K signaling pathways in a time-dependent manner, while blockade of PI3K with the specific molecular inhibitor LY294002 partially reversed the dysregulation of COX-2/PGE2 and Filaggrin. Moreover, pretreatment of HBECs with NS398, a specific molecular inhibitor of COX-2, and AH6809, a downstream PGE2 receptor inhibitor, reversed the downregulation of Filaggrin upon PM exposure. Taken together, these data demonstrated that the PI3K signaling pathway upregulated COX-2 as well as PGE2 and acted as a pivotal mediator in the downregulation of Filaggrin.
Subject(s)
Cyclooxygenase 2/metabolism , Epithelial Cells/metabolism , Intermediate Filament Proteins/metabolism , Particulate Matter/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Animals , Cell Line , Epithelium/metabolism , Filaggrin Proteins , Humans , Mice, Inbred C57BLABSTRACT
BACKGROUND: Chalcone, a natural product, has a wide range of biological activities. L2H17, a chalcone derivative, was synthesized and screened in our previous study and exhibited excellent anti-inflammatory property in vitro. This study investigated the therapeutic potential of L2H17 on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the role of heme oxygenase-1 (HO-1). MATERIALS AND METHODS: An ALI animal model was induced by LPS (10â¯mg/kg) intratracheal instillation. The effect of L2H17 on LPS-induced structural damage was determined using hematoxylin and eosin (HE) staining, and tissue edema extent was examined. Bronchoalveolar lavage fluid (BALF) was harvested to assess the levels of related cytokines by enzyme-linked immunosorbent assay (ELISA), and superoxide dismutase (SOD) activity was also assessed. HO-1 expression was determined using immunohistochemistry and western blotting. The effects of L2H17 on LPS stimulation in RAW 264.7 and the involvement of the HO-1 pathway were investigated. RESULTS: L2H17 alleviated the histopathological manifestations and tissue edema. Moreover, L2H17 decreased the production of pro-inflammatory factors in BALF and increased SOD activity. In vitro, L2H17 significantly reduced pro-inflammatory cytokine production. Additionally, L2H17 improved the expression of HO-1 in LPS-treated lung tissue and RAW 264.7. We also found that the inhibitory effect of L2H17 on the inflammatory responses was attenuated by an inhibitor of HO-1 activity, Tin protoporphyrin IX (SnPP). CONCLUSION: Our data confirmed that L2H17 can exert protective effect on ALI in vitro and in vivo by inhibiting inflammatory responses and modulating the HO-1 pathway.
