2022, Vol. 26 ›› Issue (24): 3821-3825

Effects of mechanical stretch on fiber proliferation in human lung epithelial cells

Zhang Rong, Liang Zhenting, Yang Chun, Liu Dongdong, Xi Yin, Zhang Jie, Wang Ya, Xu Yonghao, Liu Xiaoqing, Li Yimin   

Abstract: BACKGROUND: Mechanical ventilation is currently one of important and effective treatment and support methods for severe respiratory diseases, but improper mechanical ventilation can aggravate lung injury and even form fibrosis. How to minimize the lung damage associated with the ventilator and play real protective role of the ventilator is very important. The lung is a mechanical organ. Mechanical ventilation causes the alveoli to be inflated repeatedly, which stretches the neighboring lung epithelial cells, and puts it in an abnormal damage repair. Therefore, excessive mechanical stretch may play an important role in promoting the occurrence of lung fibrosis. At present, there are few reports on the effect of mechanical stretch on the proliferation of lung epithelial cells at home and abroad, and the specific mechanism is not clear.
OBJECTIVE: To investigate the effect of different mechanical stretch strengths and stretch time on expression of transforming growth factor β1, vimentin, and type I collagen in human lung epithelial BEAS-2B cells.
METHODS: Human lung epithelial BEAS-2B cells were cultured in vitro. Cells at logarithmic growth phase were divided into control static group, 10% stretch group, and 20% stretch group. The FX-5000 system was used to stretch BEAS-2B cells at 20 times/min and sine wave for 24, 48, and 72 hours. The morphological changes in cells were observed with the inverted microscope. The expression levels of transforming growth factor β1, vimentin, and type I collagen mRNA were evaluated by RT-qPCR and immunofluorescence.
RESULTS AND CONCLUSION: (1) BEAS-2B cells displayed cobblestone morphology and linked closely in the control static group. The cell morphology changed from cobblestone shape into long spindle, and intercellular space increased obviously after 20% mechanical stretch for 72 hours. (2) The expression of mRNA and protein of transforming growth factor β1, vimentin, and type I collagen in human lung epithelial BEAS-2B cells was up-regulated with increasing stretch force in a time-dependent manner compared with the control static group (P < 0.05). Compared with the control static group, the changes in transforming growth factor β1, vimentin, and type I collagen were not significant in the 10% stretch group. (3) It is concluded that mechanical stretch increases the expression of transforming growth factor β1, vimentin, and type I collagen in human lung epithelial BEAS-2B cells. Excessive mechanical stretch plays an important role in promoting lung fiber proliferation.
Key words: mechanical stretch, lung epithelial cells, pulmonary fibrosis, transforming growth factor β1, vimentin