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Effect of TGF? and PDGF-B blockade on corneal myofibroblast development in mice.

ABSTRACT: The purpose of this study was to investigate the role of transforming growth factor beta (TGF?) and/or platelet-derived growth factor-B (PDGF-B) blockade on the differentiation of vimentin and alpha-smooth muscle actin (?SMA)-expressing myofibroblasts associated with haze in mice. Mouse corneas had haze-generating irregular PTK (phototherapeutic keratectomy) and topical treatment with the vectors. Six study groups of PTK treated corneas, with four corneas per group in each experiment, were Group 1) treated with TGF?-KDEL vector interfering with TGF? signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 2) treated with PDGF-B-KDEL vector interfering with PDGF signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 3) treated with both TGF?-KDEL vector and PDGF-B-KDEL vector to interfere with signaling of both cytokines; Group 4) empty pGFPC1 vector; Group 5) empty pCMV vector; and Group 6) no vector treatment control. At one month after surgery, the corneas were analyzed by immunocytochemistry (IHC) for central stromal cells expressing myofibroblast markers vimentin and ?SMA. The stroma of corneas treated with the TGF?-KDEL vector alone (p < 0.05) or both the TGF?-KDEL and PDGF-B-KDEL vectors (P < 0.05) had significantly lower density of vimentin-positive cells compared to the corresponding control group. The central stroma of corneas treated with the TGF?-KDEL vector (p < 0.05) or the PDGF-B-KDEL vector (p < 0.05) had lower density of ?SMA-positive cells compared to the corresponding control group. The density of ?SMA-positive stromal cells was also significantly lower (p < 0.05) when both the TGF?-KDEL and PDGF-B-KDEL and vectors were applied together compared to the corresponding control groups. This study provides in situ evidence that TGF? and PDGF-B have important roles in modulating myofibroblast generation in the mouse cornea after haze-associated injury.

SUBMITTER: Singh V

PROVIDER: S-EPMC3225643 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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Effect of TGFβ and PDGF-B blockade on corneal myofibroblast development in mice.

Singh V V Santhiago M R MR Barbosa F L FL Agrawal V V Singh N N Ambati B K BK Wilson S E SE

Experimental eye research 20110929 6

The purpose of this study was to investigate the role of transforming growth factor beta (TGFβ) and/or platelet-derived growth factor-B (PDGF-B) blockade on the differentiation of vimentin and alpha-smooth muscle actin (αSMA)-expressing myofibroblasts associated with haze in mice. Mouse corneas had haze-generating irregular PTK (phototherapeutic keratectomy) and topical treatment with the vectors. Six study groups of PTK treated corneas, with four corneas per group in each experiment, were Group ...[more]

PMID: 21978952

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Project description:Transforming growth factor β (TGF-β) plays a critical role in wound healing and the pathogenesis of fibrosis (scarring). Three isoforms of TGF-β have been identified in mammals. Previous studies have shown that the addition of TGF-β1 (T1) or -β2 (T2) to human corneal fibroblasts (HCF) cultured in a 3-dimensional construct resulted in a fibrotic matrix, while the addition of TGF-β3 (T3) resulted in the production of enhanced non-fibrotic matrix as compared to control (Vitamin C [VitC] only). In the current investigation, we undertook the molecular comparison of fibrosis-related gene expression in T1 or T3-treated HCF to gain further insights into the regulation and roles of these two isoforms on the fibrotic response. HCF were cultured in 100 mm dishes in basic medium (Eagles minimum essential medium [EMEM] with 10% fetal bovine serum [FBS]). At 70-80% confluency, cells were exposed to basic medium with 0.5 mM 2-O-α-d-glucopyranosyl-l-ascorbic acid (VitC) ± 2 ng/ml of T1 or T3. After 4 h or 3 days, cells were harvested, and mRNA or protein was isolated. Fibrosis related mRNA levels were assayed using a commercial qRT-PCR Array. Selected proteins were examined using Western blotting (WB). Experiments were performed 6 times for the qRT-PCR and 4 times for WB for each condition. qRT-PCR results showed that most of the fibrosis-related genes were up or downregulated in HCF exposed to T1 or T3 as compared with VitC control. At 4 h, only Smad7 expression was significantly altered in T3-treated HCF, compared to T1, and at 3 days, five genes were altered. WB confirmed that T1 significantly decreased Smad7 expression compared to T3 and control, and that the expression of thrombospondin-1 in T3-stimulated HCF was enhanced compared to T1-treated cells. Finally, both T1 and T3 decreased Smad3 expression dramatically at both time points. At early time points, T1 and T3 have similar effects on expression of fibrosis related genes; however, with a longer exposure, an increasing number of genes were differentially expressed. Interestingly, most of the differentially expressed gene products are secreted by the cells and may be related to the modulation of extracellular matrix.

Project description:The transformation of keratocytes and fibroblasts to myofibroblasts is important to corneal wound healing as well as formation of stromal haze. The purpose of this study was to determine the effect of latrunculin B, an actin cytoskeleton disruptor in conjunction with a fundamental biophysical cue, substrate stiffness, on myofibroblast transformation in vitro and in vivo. Rabbit corneal fibroblasts were cultured on substrates of differing compliance (1.5, 22, and 71?kPa) and tissue culture plastic (TCP; > 1?GPa) in media containing 0 or 10?ng/ml TGF?1 for 72?h. Cells were treated with 0.4??M Lat-B or DMSO for 30?min every 24?h for 72?h. RNA was collected from cells and expression of alpha-smooth muscle actin (?-SMA), keratocan, and ALDH1A1 determined using qPCR; immunocytochemistry was used to assess ?-SMA protein expression. A rabbit phototherapeutic keratectomy (PTK) model was used to assess the impact of 0.1% Lat-B (n?=?3) or 25% DMSO (vehicle control, n?=?3) on corneal wound healing by assessment of epithelial wound size with fluorescein stain and semi-quantitative stromal haze scoring by an observer masked to treatment group as well as Fourier-domain optical coherence tomography (FD-OCT) at set time points. Statistical analysis was completed using one-way or two-way analysis of variance. Treatment with Lat-B versus DMSO resulted in significantly less ?SMA mRNA (P???0.007) for RCF cells grown on 22 and 71?kPa substrates as well as TCP without or with TGF?1, and significantly decreased ?-SMA protein expression in RCFs cultured on the intermediate (22?kPa) stiffness in the absence (P?=?0.028) or presence (P?=?0.018) of TGF?1. Treatment with Lat-B versus DMSO but did not significantly alter expression of keratocan or ALDH1A1 mRNA in RCFs (P?>?0.05) in the absence or presence of TGF?1, but RCFs grown on stiff hydrogels (71?kPa) had significantly more keratocan mRNA expression versus the 22?kPa hydrogel or TCP (P?<?0.001) without TGF?1. Administration of topical Lat-B BID was well tolerated by rabbits post-PTK but did not significantly alter epithelial wound closure, stromal haze score, stromal haze thickness as measured by FD-OCT in comparison to DMSO-treated rabbits. When corneal stromal cells are cultured on substrates possessing biologically relevant substratum stiffnesses, Lat-B modulates mRNA and protein expression of ?-SMA and thus modulates myofibroblast transformation. At a dose and dose-frequency that reduced IOP in human glaucoma patients, Lat-B treatment did not substantially impact corneal epithelial or stromal wound healing in a rabbit PTK model. While a significant impact on wound healing was observed at the concentration and dose frequency reported here was not found, encouraging in vitro data support further investigations of topically applied Lat-B to determine if this compound can reduce stromal fibrosis.

Dataset Information

Effect of TGF? and PDGF-B blockade on corneal myofibroblast development in mice.

Publications

Effect of TGFβ and PDGF-B blockade on corneal myofibroblast development in mice.

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