Effects of transient receptor potential canonical 1 (TRPC1) on the mechanical stretch-induced expression of airway remodeling-associated factors in human bronchial epithelioid cells

Research has shown that mechanical stress stimulation can cause airway remodeling. We investigate the effects of mechanical stretch on the expression of the airway remodeling-associated factors interleukin-13 (IL-13) and matrix metalloprotein-9 (MMP-9) and signaling pathways in human bronchial epithelioid (16HBE) cells under mechanical stretch. A Flexcell FX-4000 Tension System with a flexible substrate was applied to stretch 16HBE cells at a 15% elongation amplitude and 1 Hz frequency, with stretching for 0.5 h, 1 h, 1.5 h and 2 h. The experimental group with higher IL-13, MMP-9, and TRPC1 expression and higher Ca2+ levels was selected for performing intervention experiment. These cells were pretreated with the transient receptor potential canonical 1 (TRPC1) channel antagonist SKF96365 and TRPC1-specific siRNA, and then mechanical stretch was applied. Our results provided evidences that mechanical pressure significantly increased IL-13, MMP-9, and TRPC1 protein and mRNA expression levels and intracellular Ca2+ fluorescence intensity at 4 time points compared with the control group. The peak IL-13, MMP-9, and TRPC1 expression levels were observed at 0.5 h after exposure to mechanical pressure. IL-13 and MMP-9 expression levels and Ca2+ fluorescence intensity in the stretch+SKF96365 group and in the stretch+TRPC1 siRNA group were significantly lower than those were in the mechanical stretch group. By incubating the cells with the intracellular calcium chelator BAPTA-AM, the expression of IL-13 and MMP9 was significantly decreased, and the expression level of TRPC1 remained unchanged. These observations suggest that mechanical stretch may induce an influx of Ca2+ and up-regulation of IL-13 and MMP-9 expression in 16HBE cells via activation of TRPC1.