transforming-growth-factor-beta and Eye-Injuries

Fibrotic diseases are characterized by the appearance of myofibroblasts, the key cell type involved in the fibrogenic reaction, and by excess accumulation of extracellular matrix with resultant tissue contraction and impaired function. Myofiborblasts are generated by fibroblast-myofibrobalst conversion, and in certain tissues through epithelial-mesenchymal transition (EMT), a process through which an epithelial cell changes its phenotype to become more like a mesenchymal cell. Although inflammatory/fibrogenic growth factors/cytokines produced by injured tissues orchestrate the process of EMT, transforming growth factor beta (TGFbeta) is believed to play a central role in the process. Unlike fibrotic lesions in kidney or other tissues where myofibroblasts are generated from both fibroblasts and epithelial cells, fibrotic lesions in the eye crystalline lens are derived only from lens epithelial cells without contamination of fibroblast-derived myofibroblasts. Thus, this tissue is suitable to investigate detailed mechanisms of EMT and subsequent tissue fibrosis. EMT in retinal pigment epithelium is involved in the development of another ocular fibrotic disease, proliferative vitreoretinopathy, a fibrosis in the retina. EMT-related signal transduction cascades, i. e., TGFbeta/Smad, are a target to prevent or treat unfavorable ocular tissue fibrosis, e. g., fibrotic diseases in the crystalline lens or retina, as well as possibly in other organs.

Topics: Animals; Epithelial Cells; Extracellular Matrix; Eye Diseases; Eye Injuries; Fibrosis; Genetic Therapy; Humans; Mesoderm; Ophthalmologic Surgical Procedures; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

Excessive wound contraction can lead to scar formation in the conjunctiva. The effects of all-trans-retinoic acid (ATRA) on the contractility of human Tenon fibroblasts (HTFs) cultured in three-dimensional (3D) collagen gels were investigated.. Human Tenon fibroblasts were cultured in 3D gels of type I collagen and in the absence or presence of TGF-β, ATRA, or various inhibitors. Collagen gel contraction was evaluated by measurement of gel diameter. Phosphorylation of various signaling molecules was examined by immunoblot analysis. The formation of actin stress fibers and focal adhesions was detected by laser confocal microscopy.. All-trans-retinoic acid inhibited TGF-β-induced collagen gel contraction mediated by HTFs in a concentration- and time-dependent manner. The TGF-β-induced phosphorylation of focal adhesion kinase (FAK) and formation of stress fibers and focal adhesions in HTFs were attenuated by ATRA. All-trans-retinoic acid also inhibited the TGF-β-induced phosphorylation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase (ERK), p38, and c-Jun NH2-terminal kinase (JNK) as well as that of c-Jun and Smad2/3. Furthermore, TGF-β-induced collagen gel contraction was blocked by inhibitors of ERK, p38, or JNK signaling.. All-trans-retinoic acid inhibited TGF-β-induced collagen gel contraction mediated by HTFs, most likely by attenuating the formation of actin stress fibers and focal adhesions as well as signaling by MAPKs, c-Jun, and Smads. All-trans-retinoic acid may therefore prove effective for inhibition of conjunctival scarring through attenuation of the contractility of Tenon fibroblasts.

Topics: Cells, Cultured; Cicatrix; Collagen; Conjunctiva; Eye Injuries; Fibroblasts; Humans; Imaging, Three-Dimensional; Immunoblotting; Microscopy, Fluorescence; Tenon Capsule; Transforming Growth Factor beta; Tretinoin; Wound Healing

The aim of this study was to elucidate the mechanisms governing epithelial cell migration and proliferation during wound healing.. The authors used wound healing of mouse corneal epithelium to examine the role TGF-β signaling plays during the healing process. To achieve this goal, they used transgenic mice in which the TGF-β receptor type II (Tbr2) was conditionally ablated from the corneal epithelium. Epithelium debridement wounds were made, followed by the assessment of cell migration, proliferation, and immunostaining of various signaling pathway components.. The authors showed that in the absence of TGF-β signaling corneal epithelial wound healing is delayed by 48 hours; this corresponds to a delay in p38MAPK activation. Despite the delayed p38MAPK activation, ATF2, a substrate of p38MAPK, is still phosphorylated, leading to the suppression of cell proliferation at the leading edge of the wound. These data provide evidence that in the absence of TGF-β signaling, the suppression of cell proliferation during the early stages of wound healing is maintained through the JNK activation of ATF2. CONCLUSIONS; Together the data presented here demonstrate the importance of the TGF-β and MAPK signaling pathways in corneal epithelial wound healing.

Topics: Activating Transcription Factor 2; Animals; Cell Communication; Cell Movement; Cell Proliferation; Debridement; Epithelium, Corneal; Eye Injuries; Female; Fluorescent Antibody Technique, Indirect; Male; MAP Kinase Signaling System; Mice; Mice, Transgenic; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Transforming Growth Factor beta; Wound Healing; Wounds, Nonpenetrating

An alkali burn in the cornea is a common serious clinical problem often leading to permanent visual impairment. Since transforming growth factor-beta (TGF-beta) is involved in the response to corneal injury, we evaluated the therapeutic effects of adenoviral gene transfer of mouse bone morphogenic protein-7 (BMP-7), which has antagonistic effects on TGF-beta in tissue fibrosis. Burned cornea did not express endogenous BMP-7 mRNA and protein. Resurfacing of the burned cornea by invading conjunctival epithelium was accelerated by adenoviral introduction of BMP-7. Exogenous BMP-7 expression also suppressed myofibroblast generation, appearance of monocytes/macrophages and expression of MCP-1, TGF-betas, and collagen I alpha2 chain in the affected stroma. Ectopic BMP-7 did not suppress stromal neovascularization throughout the interval studied and also did not reduce VEGF mRNA expression at Day 10. Ectopic BMP-7 in burned corneal tissue resulted in activation of Smad1/5/8 signaling and partial suppression of the phospho-Smad2 signal. These data suggest that overexpression of BMP-7 is an effective strategy for treatment of ocular alkali burns.

Topics: Adenoviridae; Animals; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Cell Division; Corneal Diseases; Disease Models, Animal; DNA-Binding Proteins; Eye Injuries; Gene Transfer Techniques; Immunohistochemistry; Mice; Mice, Inbred C57BL; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Smad Proteins; Smad1 Protein; Trans-Activators; Transforming Growth Factor beta

We examined the effect of adenovirus-mediated transient expression of Smad7, an inhibitory Smad in TGFbeta/activin signaling, on injury-induced epithelial-mesenchymal transition (EMT) of lens epithelium in mice. A volume of 3 microl of adenoviral solution was injected into the right lens of adult male C57BL/6 mice (n=56) at the time of capsular injury made using a hypodermic needle under general anesthesia. A mixture of recombinant adenovirus carrying CAG promoter-driven Cre (Cre adv) and mouse Smad7 complementary DNA (Smad7 adv) was administered to induce Smad7 expression, while control lenses were treated with Cre adv alone. After healing intervals of 2, 3, 5, and 10 days, animals were killed 2 h after labeling with bromodeoxyuridine (BrdU) and eyes were processed for histology. During healing, marked expression of Smad7 was observed in lens epithelial cells in the Smad7 adv group with loss of nuclear translocation of Smads2/3, while little Smad7 and abundant nuclear Smads2/3 were seen in cells in the Cre adv group. Lens epithelial cells in the Cre adv control group exhibited a fibroblastic appearance at days 5 and 10 and the capsular break was sealed with fibrous tissue, while Smad7 adv-treated cells around the capsular break retained their epithelial morphology and the break was not sealed. Expression of snail mRNA, and alpha-smooth muscle actin, lumican, and collagen VI proteins, markers of EMT, was observed in control-treated eyes, but not in cells of the Smad7 adv group at day 5 with minimal expression at day 10. Additionally, cell proliferation increased in epithelium infected with Smad7 adv consistent with suppression of injury-induced upregulation of TGFbeta1 in epithelium. We conclude that gene transfer of Smad7 in mice prevents injury-induced EMT of lens epithelial cells and sealing of the capsular break with fibrous tissue.

Topics: Actins; Adenoviridae; Animals; Cell Division; Chondroitin Sulfate Proteoglycans; Collagen Type VI; Disease Models, Animal; DNA-Binding Proteins; Epithelial Cells; Eye Injuries; Gene Expression Regulation; Genetic Therapy; Genetic Vectors; Keratan Sulfate; Lens Capsule, Crystalline; Lens, Crystalline; Lumican; Male; Mesoderm; Mice; Mice, Inbred C57BL; RNA, Messenger; Smad7 Protein; Trans-Activators; Transduction, Genetic; Transforming Growth Factor beta; Wound Healing

To evaluate whether vitreous surgery is successful in closing full-thickness traumatic macular holes and whether there is subsequent improvement in visual acuity.. Twelve eyes from 12 consecutive patients with traumatic macular holes underwent vitrectomy, fluid-gas exchange and instillation of bovine or recombinant transforming growth factor (TGF)-beta-2. Three of four eyes underwent repeat vitrectomy with TGF-beta-2 after the initial procedure failed to close the macular hole.. Eleven (92%) of 12 eyes had closure of the macular hole. Follow-up ranged from 3 to 33 months. Visual acuity improved by 2 or more lines in 8 (67%) of 12 eyes. Six (50%) of 12 eyes improved to 20/40 or better. All 3 eyes that underwent reoperation had successful closure of the macular hole and achieved 2 or more lines of visual improvement.. Treatment of full-thickness traumatic macular holes with vitrectomy, fluid-gas exchange, and TGF-beta-2 may result in successful anatomic closure and visual improvement.

Topics: Adolescent; Adult; Air; Child; Eye Injuries; Female; Fluorescein Angiography; Fluorocarbons; Follow-Up Studies; Humans; Male; Ophthalmic Solutions; Recombinant Proteins; Reoperation; Retina; Retinal Perforations; Transforming Growth Factor beta; Treatment Outcome; Visual Acuity; Vitrectomy; Wounds, Nonpenetrating