ABSTRACT
Idiopathic pulmonary fibrosis (IPF) is characterized by myofibroblast foci in lung parenchyma.Myofibroblasts are thought to originate from epithelial-to-mesenchymal transition (EMT).Wnt1 and lithium chloride (LiCl) induce EMT in alveolar epithelial cells (AECs),but the mechanisms are unclear.AECs were treated with Wnt1 and LiCl,respectively;morphological change and molecular changes of EMT,including E-cadherin,fibronectin,and vimentin,were observed.SB203580 was administrated to test the role of p38 MAPK signaling in EMT.Then AECs were treated with siRNAs targeting p38 MAPK to further test the effects of p38 MAPK,and the role was further confirmed by re-expression of p38 MAPK.At last β-catenin siRNA was used to test the role of β-catenin in the EMT process and relationship of β-catenin and p38 MAPK was concluded.Exposure of AECs to Wnt1 and LiCl resulted in upregulation of vimentin and fibronectin with subsequent downregulation of E-cadherin.Wnt1 and LiCl stimulated the p38 MAPK signaling pathways.Perturbing the p38 MAPK pathway either by SB203580 or through p38 MAPK siRNA blocked EMT and inhibited fibronetin synthesis,which were reversed by transfection of p38 MAPK expression plasmid.β-catenin siRNA attenuated the EMT process and decreased p38 MAPK phosphorylation,indicating that β-catenin is involved in the EMT-related changes through regulation of p38 MAPK phosphorylation.These findings suggest that p38 MAPK participates in the pathogenesis of EMT through Wnt pathway and that p38 MAPK may be a novel target for IPF therapy.
ABSTRACT
Idiopathic pulmonary fibrosis (IPF) is characterized by myofibroblast foci in lung parenchyma.Myofibroblasts are thought to originate from epithelial-to-mesenchymal transition (EMT).Wnt1 and lithium chloride (LiCl) induce EMT in alveolar epithelial cells (AECs),but the mechanisms are unclear.AECs were treated with Wnt1 and LiCl,respectively;morphological change and molecular changes of EMT,including E-cadherin,fibronectin,and vimentin,were observed.SB203580 was administrated to test the role of p38 MAPK signaling in EMT.Then AECs were treated with siRNAs targeting p38 MAPK to further test the effects of p38 MAPK,and the role was further confirmed by re-expression of p38 MAPK.At last β-catenin siRNA was used to test the role of β-catenin in the EMT process and relationship of β-catenin and p38 MAPK was concluded.Exposure of AECs to Wnt1 and LiCl resulted in upregulation of vimentin and fibronectin with subsequent downregulation of E-cadherin.Wnt1 and LiCl stimulated the p38 MAPK signaling pathways.Perturbing the p38 MAPK pathway either by SB203580 or through p38 MAPK siRNA blocked EMT and inhibited fibronetin synthesis,which were reversed by transfection of p38 MAPK expression plasmid.β-catenin siRNA attenuated the EMT process and decreased p38 MAPK phosphorylation,indicating that β-catenin is involved in the EMT-related changes through regulation of p38 MAPK phosphorylation.These findings suggest that p38 MAPK participates in the pathogenesis of EMT through Wnt pathway and that p38 MAPK may be a novel target for IPF therapy.
ABSTRACT
<p><b>BACKGROUND</b>The experimental studies of venous thromboembolism (VTE) as an entity and the response of the pulmonary arterial endothelium after VTE are still rare. The objective of this study was to observe changes in the pulmonary arterial endothelium using a novel rat model of VTE.</p><p><b>METHODS</b>Rats were allocated to the VTE (n = 54) or control groups (n = 9). The left femoral vein was blocked using a microvessel clip to form deep vein thrombosis (DVT). One, four or seven-day-old thrombi were injected into the right femoral vein to induce DVT-pulmonary thromboembolism (DVT-PTE). The rats were sacrificed 1, 4 or 7 days later (D(n(1,4,7)) P(n(1,4,7)) subgroups (n = 6)), and the lungs were examined using light and electron microscopy.</p><p><b>RESULTS</b>On gross dissection, the rate of DVT formation was higher on day 1 (D(1)P(n): 100%, 18/18) than day 4 (D(4)P(n): 83%, 15/18; χ(2) = 5.900, P = 0.015) or day 7 (D(7)P(n): 44%, 8/18; χ(2) = 13.846, P = 0.000). On gross dissection, the positive emboli residue rate in the pulmonary arteries was lower in the D(1)P(n) subgroup (39%, 7/18) than the D(4)P(n) (73%, 11/15; χ(2) = 3.915, P = 0.048) and D(7)P(n) subgroups (100%, 8/8; χ(2) = 8.474, P = 0.004); however, light microscopy indicated the residual emboli rate was similar in all subgroups. Hyperplasia of the pulmonary arterial endothelium was observed 4 and 7 days after the injection of one-day-old or four-day-old thrombi. However, regions without pulmonary arterial endothelial cells and intra-elastic layers were observed one day after injection of seven-day-old thrombi.</p><p><b>CONCLUSIONS</b>This novel model closely simulates the clinical situations of thrombus formation and is ideal to study pulmonary endothelial cell activation. The outcome of emboli and pulmonary arterial endothelial alterations are related to the age and nature of the thrombi.</p>