Objective To investigate whether N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) could inhibit epithelialmesenchymal transition of human typeⅡ alveolar epithelial cells through suppressing the expression of heat shock protein27 (HSP27) and the deposition of typeⅠand type Ⅲ collagen mediated by transforming growth factor beta 1 (TGF-β1).
Methods Human type Ⅱ alveolar epithelial cell line A549 was induced by 5 ng/mL TGF-β1 in vitro for 72 hours and divided into control, TGF-β1, and 10-8 mol/L Ac-SDKP intervention groups. Morphological changes of epithelial-mesenchymal transition in A549 cells were observed by phase-contrast microscopy. Immunocytochemical methods were used to determine the locations of cytokeratin 8 (CK8) and vimentin. The expressions of E-cadherin (E-cad), CK8, vimentin, α-smooth muscle actin (α-SMA), HSP27, and type Ⅰ and type Ⅲ collagen were detected by Western blot analysis.
Results The A549 cells formed spindle-like after exposed to TGF-β1. Coincident with these morphological changes, the expression levels of CK8 and E-cad decreased to 40% and 50% as compared to the control group, while those of vimentin and α-SMA increased to 1.9 and 1.8 folds respectively (P<0.05). This process was accompanied by increases in levels of HSP27, type Ⅰ collagen, and type Ⅲ collagen by 1.9, 2.2, and 2.5 folds (P<0.05). After Ac-SDKP in tervention, the expressions of CK8 and E-cad increased by 2.6 folds and 2.0 folds respectively as compared to the TGF-β1 group; while the expressions of vimentin, α-SMA, HSP27, type Ⅰcollagen, and Ⅲ were decreased to 68%, 66%, 74%, 66%, and 44% comparing with the TGF-β1 group (P<0.05).
Conclusion Ac-SDKP could inhibit the transition of cultured human type Ⅱ alveolar epithelial cells to myofibroblasts and attenuate collagen synthesis through modulating the expression of HSP27.
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