Glucocorticoid-induced contractility and F-actin content of human lung fibroblasts in three-dimensional culture

Glucocorticoid-induced contractility and F-actin content of human lung fibr oblasts in three-dimensional culture. Am. J. Physiol. Lung Cell. Mel. Physi ol. 278: L13-L18, 2000.--Fibroblast contractility plays a useful role in th e wound healing process but contributes to architectural distortion in the lungs. Glucocorticoids (GCs) have been reported to reduce dermal fibroblast contractility, which may result in delaying wound healing, but the effects on lung fibroblasts are unknown. In this study, we examined how human lung fibroblast contractility is altered in the presence of GCs. Lung fibroblas t cell lines (n = 5) were established from normal parts of surgically resec ted lung tissue. The effects of GCs on contractility were investigated with a type I collagen gel contraction assay. Filamentous actin (F-actin) conte nt was detected by confocal microscopy and measured with a fluorescent phal loidin binding assay. GCs augmented fibroblast contraction in a concentrati on-dependent manner, with an approximate EC50 of 1.8 x 10(-8) M, whereas ot her steroid derivatives had no effects. GC contractility needed de novo pro tein synthesis. The GC-induced increase in contractility was found to be co nsistent with an increase in F-actin content. In conclusion, lung fibroblas t contractility was enhanced with GCs through an upregulation of lung fibro blast F-actin.