Simvastatin impairs smad-3 phosphorylation and modulates transforming growth factor beta1-mediated activation of intestinal fibroblasts.

Transforming growth factor (TGF) beta1, acting through the smad pathway, is critical to fibroblast-mediated intestinal fibrosis. Simvastatin exhibits antifibrotic properties. This study assessed the effects of simvastatin on TGF-beta1-mediated intestinal fibroblast activation. Human intestinal fibroblasts were activated with TGF-beta1 with or without simvastatin or the cholesterol pathway intermediates farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). Collagen-Ialpha2 expression was assessed by reverse transcriptase-polymerase chain reaction. Connective tissue growth factor (CTGF) and smad phosphorylation were evaluated by western blot, and plasminogen activator inhibitor (PAI) 1 activity by enzyme-linked immunosorbent assay. Fibroblast filamentous (F)-actin accumulation was assessed by confocal microscopy and contraction by a fibroblast-populated collagen lattice (FPCL) model. TGF-beta1 treatment of fibroblasts induced smad-2/3 phosphorylation, CTGF and collagen-Ialpha2 production, F-actin bundling, FPCL contraction and PAI-1 activation. Pretreatment with simvastatin inhibited the induction of CTGF and collagen-Ialpha2, PAI-1 activation, F-actin bundling and FPCL contraction. The inhibitory effect of simvastatin on PAI-1 activation was reversed by GGPP and FPP. Simvastatin pretreatment inhibited TGF-beta1-mediated phosphorylation of smad-3. Simvastatin abrogates TGF-beta1-mediated intestinal fibroblast activation by inhibition of smad-3 phosphorylation. These findings offer a mechanism for the antifibrotic effects of simvastatin and a therapeutic entry point in the treatment of intestinal fibrosis.

Burke JP ，Watson RW ，Murphy M ，Docherty NG ，Coffey JC ，O'Connell PR ... -  《-》

Simvastatin inhibits transforming growth factor-β1-induced expression of type I collagen, CTGF, and α-SMA in keloid fibroblasts.

Simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitor, is used to reduce cholesterol levels. Accumulating evidence has revealed the immunomodulatory and anti-inflammatory effects of simvastatin that prevent cardiovascular diseases. In addition, the beneficial effects of statins on fibrosis of various organs have been reported. However, the functional effect of statins on dermal fibrosis of keloids has not yet been explored. The objective of this study was to determine whether simvastatin could affect dermal fibrosis associated with keloids. We examined the effect of simvastatin on transforming growth factor (TGF)-β1-induced production of type I collagen, connective tissue growth factor (CTGF or CCN2), and α-smooth muscle actin (α-SMA). Keloid fibroblasts were cultured and exposed to different concentrations of simvastatin in the presence of TGF-β1, and the effects of simvastatin on TGF-β1-induced collagen and CTGF production in keloid fibroblasts were determined. The type I collagen, CTGF, and α-SMA expression levels and the Smad2 and Smad3 phosphorylation levels were assessed by Western blotting. The effect of simvastatin on cell viability was evaluated by assessing the colorimetric conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. Simvastatin suppressed TGF-β1-induced type I collagen, CTGF, and α-SMA production in a concentration-dependent manner. The TGF-β1-induced Smad2 and Smad3 phosphorylation levels were abrogated by simvastatin pretreatment. The inhibition of type I collagen, CTGF, and α-SMA expression by simvastatin was reversed by geranylgeranyl pyrophosphate, suggesting that the simvastatin-induced cellular responses were due to inhibition of small GTPase Rho involvement. A RhoA activation assay showed that preincubation with simvastatin significantly blocked TGF-β1-induced RhoA activation. The Rho-associated coiled kinase inhibitor Y27632 abrogated TGF-β1-induced production of type I collagen, CTGF, and α-SMA. However, Y27632 had no significant effect on TGF-β1-induced phosphorylation of Smad2 and Smad3. In conclusion, the present study suggests that simvastatin is an effective inhibitor of TGF-β1-induced type I collagen, CTGF, and α-SMA production in keloid fibroblasts.

Mun JH ，Kim YM ，Kim BS ，Kim JH ，Kim MB ，Ko HC ... -  《-》

Lovastatin inhibits oxidized low-density lipoprotein-induced plasminogen activator inhibitor and transforming growth factor-beta1 expression via a decrease in Ras/extracellular signal-regulated kinase activity in mesangial cells.

Song CY ，Kim BC ，Lee HS 《-》

Bacterial lipopolysaccharide promotes profibrotic activation of intestinal fibroblasts.

Fibroblasts play a critical role in intestinal wound healing. Lipopolysaccharide (LPS) is a cell wall component of commensal gut bacteria. The effects of LPS on intestinal fibroblast activation were characterized. Expression of the LPS receptor, toll-like receptor (TLR) 4, was assessed in cultured primary human intestinal fibroblasts using flow cytometry and confocal microscopy. Fibroblasts were treated with LPS and/or transforming growth factor (TGF) beta1. Nuclear factor kappaB (NFkappaB) pathway activation was assessed by inhibitory kappaBalpha (IkappaBalpha) degradation and NFkappaB promoter activity. Fibroblast contractility was measured using a fibroblast-populated collagen lattice. Smad-7, a negative regulator of TGF-beta1 signalling, and connective tissue growth factor (CTGF) expression were assessed using reverse transcriptase-polymerase chain reaction and western blot. The NFkappaB pathway was inhibited by IkappaBalpha transfection. TLR-4 was present on the surface of intestinal fibroblasts. LPS treatment of fibroblasts induced IkappaBalpha degradation, enhanced NFkappaB promoter activity and increased collagen contraction. Pretreatment with LPS (before TGF-beta1) significantly increased CTGF production relative to treatment with TGF-beta1 alone. LPS reduced whereas TGF-beta1 increased smad-7 expression. Transfection with an IkappaBalpha plasmid enhanced basal smad-7 expression. Intestinal fibroblasts express TLR-4 and respond to LPS by activating NFkappaB and inducing collagen contraction. LPS acts in concert with TGF-beta1 to induce CTGF. LPS reduces the expression of the TGF-beta1 inhibitor, smad-7.

Burke JP ，Cunningham MF ，Watson RW ，Docherty NG ，Coffey JC ，O'Connell PR ... -  《-》

Contractility as a prerequisite for TGF-beta-induced myofibroblast transdifferentiation in human tenon fibroblasts.

Meyer-ter-Vehn T ，Sieprath S ，Katzenberger B ，Gebhardt S ，Grehn F ，Schlunck G ... -  《INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE》