Emodin inhibiting neutrophil elastase-induced epithelial-mesenchymal transition through Notch1 signalling in alveolar epithelial cells.

The transition of alveolar type II epithelial cells into fibroblasts has been reported to cause and/or aggravate pulmonary fibrosis (PF), which is characterized by fibroblast proliferation, an enhanced production and accumulation of ECM (extracellular matrix), alveolar wall damage and functional capillary unit loss. Traditional Chinese medicine Emodin has been reported to inhibit TGF-ß-induced epithelial-mesenchymal transition (EMT) in alveolar epithelial cells through Notch signalling. In the present study, neutrophil elastase (NE, also known as ELA2) treatment promoted EMT, Notch1 cleavage (NICD/Notch1 ratio increase) and NICD nuclear translocation in RLE-6TN cells and A549 cells. The promotive roles of NE treatment in these events were significantly reversed by Notch1 knockdown. Traditional Chinese medicine Emodin treatment remarkably inhibited the enzyme activity of NE, suppressed EMT, Notch1 cleavage and NICD nuclear translocation within RLE-6TN and A549 cells, while NE treatment significantly reversed the effects of Emodin. Moreover, in RLE-6TN, the effects of NE on EMT, Notch1 cleavage and NICD nuclear translocation were remarkably attenuated by Emodin treatment and more attenuated by the combination of Emodin and neutrophil elastase inhibitor Sivelestat or notch signal pathway inhibitor DAPT. In conclusion, we revealed the involvement of NE-induced Notch1 cleavage in the functions of Emodin suppressing NE-caused EMT in RLE-6TN cells and A549 cells. This novel mechanism of Emodin inhibiting EMT might extend the application of Emodin in PF treatment.

[Effect of Polydatin on Epithelial-Mesenchymal Transition of Human Alveolar Epithelium A549 Cells Induced by TGF-ß1].

OBJECTIVE: To explore the effect of polydatin on the growth of TGF-ß1induced humanalveolar epithelium A549 cells and the mechanism of polydatin for inhibiting the process of epithelial-mesenchymal transition (EMT). METHODS: A549 cells in vitro cultured were randomly divided into five groups, i.e., the blank group, the control group, the low dose polydatin group, the middle dose polydatin group, the high dose polydatin group. Common culture fluid was added in A549 cells of the blank group. Five ng/mLTGF-ß1contained culture fluid was added in A549 cells of the control group. 50, 100, and 150 µmol/mL of polydatin plus 5 ng/mL TGF-ß1contained culture fluid was added in A549 cells of low, middle, and high dosepolydatin groups, respectively. Morphological changes were observed and recorded at different time points. The optimal concentration of polydatin was determined by MTT method. Protein and mRNA expressions of E-cad epithelial cell marker) and Vimentin (mesenchymal cell marker) were detected by Western blot and Real-time PCR. RESULTS: Under inverted phase contrast microscope, A549 cells turned from previous pebble shape to fusiform shape after intervened by polydatin and TGF-ß1. The intercellular space was enlargedand the intercellular connection became loose. These phenomena were more obviously seen in the control group. A549 cells were more satiated in low, middle, and high dose polydatin groups than in the control group. The EMT inhibition was most obviously seen in the middle dose polydatin group at 48 h. Protein and mRNA expressions of E-cad showed an overall descending tendency after intervened by polydatin and TGF-ß1 (P < 0.05). But compared with the control group, protein and mRNA expressions of E-cad were down-regulated in a lesser amplitude in each intervened group. Besides, the tendency was more obviously seen at 48 h than at 24 h. Protein and mRNA expressions of Vimentin showed an overall up-regulating tendency. But compared with the control group, protein and mRNA expressions of Vimentin were down-regulated in a lesser amplitude in each intervened group. Besides, the tendency was more obviously seen at 48 h than at 24 h (P < 0.05). CONCLUSIONS Polydatin could inhibit TGF-ß1 induced EMT process of A549 cells time- and dose-dependently. It also played roles in inhibiting pulmonary fibrosis.