Sensory nerve supports epithelial stem cell function in healing of corneal epithelium in mice: the role of trigeminal nerve transient receptor potential vanilloid 4.

In order to understand the pathobiology of neurotrophic keratopathy, we established a mouse model by coagulating the first branch of the trigeminal nerve (V1 nerve). In our model, the sensory nerve in the central cornea disappeared and remaining fibers were sparse in the peripheral limbal region. Impaired corneal epithelial healing in the mouse model was associated with suppression of both cell proliferation and expression of stem cell markers in peripheral/limbal epithelium as well as a reduction of transient receptor potential vanilloid 4 (TRPV4) expression in tissue. TRPV4 gene knockout also suppressed epithelial repair in mouse cornea, although it did not seem to directly modulate migration of epithelium. In a co-culture experiment, TRPV4-introduced KO trigeminal ganglion upregulated nerve growth factor (NGF) in cultured corneal epithelial cells, but ganglion with a control vector did not. TRPV4 gene introduction into a damaged V1 nerve rescues the impairment of epithelial healing in association with partial recovery of the stem/progenitor cell markers and upregulation of cell proliferation and of NGF expression in the peripheral/limbal epithelium. Gene transfer of TRPV4 did not accelerate the regeneration of nerve fibers. Sensory nerve TRPV4 is critical to maintain stemness of peripheral/limbal basal cells, and is one of the major mechanisms of homeostasis maintenance of corneal epithelium.

The murine lens: A model to investigate in vivo epithelial-mesenchymal transition.

Epithelial-mesenchymal transition (EMT) produces myofibroblasts that contribute to the formation of fibrotic tissue with an impairment of tissue homeostasis and functionality. The crystalline lens of the eye is a unique transparent and isolated tissue. The lens vesicle becomes isolated from the surface ectoderm, its cells are all contained as they line the inner surface of the lens capsule. Clinically the formation of fibrotic tissue by the lens epithelial cells causes a type of cataract or opacification and contraction of the lens capsule postcataract surgery. Production of EMT in the intact animal lens by using specific gene transfer to the lens or experimental lens injury has been shown to be a powerful tool to investigate EMT processes. It is not easy to uncover whether the origin of the myofibroblast is epithelial cell-derived or from other cell lineages in fibrotic tissues. However, myofibroblasts that appear in the crystalline lens pathology are totally derived from the lens epithelial cells for the reasons mentioned above. Here, we report on different animal models of lens EMT, using either transgenic approaches or injury to study the biological aspects of EMT. Developmental Dynamics 247:340-345, 2018. © 2017 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Ocular surface inflammation impairs structure and function of meibomian gland.

Dysfunction of the meibomian glands alters secreted meibum quantitatively and qualitatively that can lead to damage to the ocular surface epithelium. In response to an unstable tear film cause by meibomian gland dysfunction, ocular surface epithelium is damaged and expresses inflammatory cytokines leading to secondary ocular inflammation. In turn, inflammatory disorders of the palpebral conjunctiva and lid margin may affect the structure and function of meibomian gland. The disorders include allergic conjunctivitis, long-term usage of contact lenses, dermatological diseases that affect conjunctival homeostasis, Stevens-Johnson's syndrome or chemical burning of the ocular surface and lid margin.

Loss of TRPV4 Function Suppresses Inflammatory Fibrosis Induced by Alkali-Burning Mouse Corneas.

In humans suffering from pulmonary disease and a mouse model, transient receptor potential vanilloid 4 (TRPV4) channel activation contributes to fibrosis. As a corneal alkali burn induces the same response, we determined if such an effect is also attributable to TRPV4 activation in mice. Accordingly, we determined if the alkali burn wound healing responses in wild-type (WT) mice are different than those in their TRPV4-null (KO) counterpart. Stromal opacification due to fibrosis in KO (n = 128) mice was markedly reduced after 20 days relative to that in WT (n = 157) mice. Immunohistochemistry revealed that increases in polymorphonuclear leukocytes and macrophage infiltration declined in KO mice. Semi-quantitative real time RT-PCR of ocular KO fibroblast cultures identified increases in proinflammatory and monocyte chemoattractant protein-1 chemoattractant gene expression after injury. Biomarker gene expression of fibrosis, collagen1a1 and α-smooth muscle actin were attenuated along with macrophage release of interleukin-6 whereas transforming growth factor ß, release was unchanged. Tail vein reciprocal bone marrow transplantation between WT and KO chimera mouse models mice showed that reduced scarring and inflammation in KO mice are due to loss of TRPV4 expression on both corneal resident immune cells, fibroblasts and infiltrating polymorphonuclear leukocytes and macrophages. Intraperitoneal TRPV4 receptor antagonist injection of HC-067047 (10 mg/kg, daily) into WT mice reproduced the KO-phenotype. Taken together, alkali-induced TRPV4 activation contributes to inducing fibrosis and inflammation since corneal transparency recovery was markedly improved in KO mice.

Suppression of In Vivo Neovascularization by the Loss of TRPV1 in Mouse Cornea.

To investigate the effects of loss of transient receptor potential vanilloid receptor 1 (TRPV1) on the development of neovascularization in corneal stroma in mice. Blocking TRPV1 receptor did not affect VEGF-dependent neovascularization in cell culture. Lacking TRPV1 inhibited neovascularization in corneal stroma following cauterization. Immunohistochemistry showed that immunoreactivity for active form of TGFß1 and VEGF was detected in subepithelial stroma at the site of cauterization in both genotypes of mice, but the immunoreactivity seemed less marked in mice lacking TRPV1. mRNA expression of VEGF and TGFß1 in a mouse cornea was suppressed by the loss of TRPV1. TRPV1 gene ablation did not affect invasion of neutrophils and macrophage in a cauterized mouse cornea. Blocking TRPV1 signal does not affect angiogenic effects by HUVECs in vitro. TRPV1 signal is, however, involved in expression of angiogenic growth factors in a cauterized mouse cornea and is required for neovascularization in the corneal stroma in vivo.

Transient Receptor Potential Channels and Corneal Stromal Inflammation.

Corneal transparency is dependent on the maintenance of the structural integrity and functional activity of its epithelial and endothelial limiting layers and the stroma. Different transient receptor potential (TRP) channel subtypes are expressed in cells and on corneal sensory nerve endings. They serve as sensors and transducers of environmental stimuli that can reduce tissue transparency. These nonselective cation channels are members of a superfamily sharing TRP box protein sequence homology having 6 membrane spanning domains with a pore between the fifth and sixth segments. TRP channels are composed of 4 monomeric subunits that oligomerize in homomeric or heteromeric configurations derived from different TRP subtypes belonging to the same or any of 6 different subfamilies. TRP subfamily members identified in the cornea include those belonging to the canonical, vanilloid, ankyrin, or melastatin subfamilies. In this review, we specifically focus on the functional roles of TRPV1 and TRPA1 expression in the cornea as their activation provides adaptive nociceptive and immune responses to noxious environmental stresses such as irritating ligands, temperature fluctuations, rises in ambient osmolarity, mechanical stretch, decline in pH, and tissue injury. Our previous studies have indicated that TRPV1 and TRPA1 subtypes are potential drug targets for improving corneal wound healing after alkali burns, because injury-induced fibrosis, neovascularization, and inflammation in either TRPV1 or TRPA1 gene-silenced mice were all significantly reduced.

Ocular surface mucins and local inflammation--studies in genetically modified mouse lines.

Mucins locate to the apical surfaces of all wet-surfaced epithelia including ocular surface. The functions of the mucins include anti-adhesive, lubrication, water retention, allergens and pathogen barrier function. Ocular surface pathologies, i.e. dry eye syndrome or allergic conjunctivitis, are reportedly associated with alteration of expression pattern of mucin components. Recent investigations indicated anti-bacterial adhesion or anti-inflammatory effects of members of mucins in non-ocular tissues, i.e., gastrointestinal tracts or airway tissues, by using genetically modified mouse lines that lacks an expression of a mucin member. However, examination of ocular phenotypes of each of mucin gene-ablated mouse lines has not yet fully performed. Muc16-deficient mouse is associated with spontaneous subclinical inflammation in conjunctiva. The article reviews the roles of mucin members in modulation of local inflammation in mucous membrane tissues and phenotype of mouse lines with the loss of a mucin gene. Analysis of ocular surface of mucin-gene related mutant mouse lines are to be further performed.

TRPA1 is required for TGF-ß signaling and its loss blocks inflammatory fibrosis in mouse corneal stroma.

We examined whether the loss of transient receptor potential ankyrin 1 (TRPA1), an irritant-sensing ion channel, or TRPA1 antagonist treatment affects the severity inflammation and scarring during tissue wound healing in a mouse cornea injury model. In addition, the effects of the absence of TRPA1 on transforming growth factor ß1 (TGF-ß1)-signaling activation were studied in cell culture. The lack of TRPA1 in cultured ocular fibroblasts attenuated expression of TGF-ß1, interleukin-6, and α-smooth muscle actin, a myofibroblast the marker, but suppressed the activation of Smad3, p38 MAPK, ERK, and JNK. Stroma of the healing corneas of TRPA1(-/-) knockout (KO) mice appeared more transparent compared with those of wild-type mice post-alkali burn. Eye globe diameters were measured from photographs. An examination of the corneal surface and eye globes suggested the loss of TRPA1 suppressed post-alkali burn inflammation and fibrosis/scarring, which was confirmed by histology, immunohistochemistry, and gene expression analysis. Reciprocal bone marrow transplantation between mice showed that KO corneal tissue resident cells, but not KO bone marrow-derived cells, are responsible for KO mouse wound healing with reduced inflammation and fibrosis. Systemic TRPA1 antagonists reproduced the KO phenotype of healing. In conclusion, a loss or blocking of TRPA1 in mice reduces inflammation and fibrosis/scarring in the corneal stroma during wound healing following an alkali burn. The responsible mechanism may include the inhibition of TGF-ß1-signaling cascades in fibroblasts by attenuated TRPA1 signaling. Inflammatory cells are considered to have a minimum involvement in the exhibition of the KO phenotype after injury.

Effects of the loss of conjunctival Muc16 on corneal epithelium and stroma in mice.

PURPOSE: To examine the role of conjunctival Muc16 in the homeostasis of the ocular surface epithelium and stroma using Muc16-null knockout (KO) mice. METHODS: We used KO mice (n = 58) and C57/BL6 (WT) mice (n = 58). Histology and immunohistochemistry were employed to analyze the phenotypes in the ocular surface epithelium. The expression of phospho-Stat3, AP-1 components, interleukin 6 (IL-6), and tumor necrosis factor-α (TNFα) in the cornea and conjunctiva was examined. The shape of the nuclei of corneal epithelial cells was examined to evaluate intraepithelial cell differentiation. Epithelial cell proliferation was studied using bromo-deoxyuridine labeling. Finally, the wound healing of a round defect (2-mm diameter) in the corneal epithelium was measured. The keratocyte phenotype and macrophage invasion in the stroma were evaluated after epithelial repair. RESULTS: The loss of Muc16 activated Stat3 signal, affected JunB signal, and upregulated the expression of IL-6 in the conjunctiva. Basal-like cells were observed in the suprabasal layer of the corneal epithelium with an increase in proliferation. The loss of Muc16 accelerated the wound healing of the corneal epithelium. The incidence of myofibroblast appearance and macrophage invasion were more marked in KO stroma than in WT stroma after epithelial repair. CONCLUSIONS: The loss of Muc16 in the conjunctiva affected the homeostasis of the corneal epithelium and stroma. The mechanism might include the upregulation of the inflammatory signaling cascade (i.e., Stat3 signal, and IL-6 expression in the KO conjunctiva). Current data provides insight into the research of the pathophysiology of dry eye syndrome.

Impairment of corneal epithelial wound healing in a TRPV1-deficient mouse.

PURPOSE: To examine whether the absence or blockage of an ion channel receptor, transient receptor potential vanilloid subtype 1 (TRPV1), affects the healing of an epithelial injury using an experimental model of an epithelial defect in animal cornea. METHODS: The expression of TRPV1 in the corneal epithelium was examined using immunohistochemistry in mice and rats. The migration of the corneal epithelium was examined in epithelium-debrided rat cornea in organ culture in the presence or absence of a TRPV1 agonist or its antagonist. Epithelial migration and cell proliferation following the debridement were examined in the cornea of a TRPV1-null mouse. Real-time RT-PCR was performed in samples of healing corneas to analyze the expression pattern of epithelial migration-related components (i.e., IL-6, substance P, and TGF-ß1). RESULTS: TRPV1 was detected mainly in the basal layer of mouse or rat corneal epithelium. Adding a TRPV1 receptor agonist to the culture medium enhanced epithelial healing in the rat cornea, and a TRPV1 antagonist retarded it in organ culture. The loss of TRPV1 did not affect the histology of the mouse cornea. In vivo analysis showed the loss of TRPV1-impaired re-epithelialization of the debrided area of the corneal epithelium by the suppression of both cell migration and proliferation. The lack of TRPV1 suppressed the expression of IL-6 and substance P but not of TGF-ß1 in response to epithelial debridement in mice. CONCLUSIONS: TRPV1 signal is required for the upregulation of IL-6 and substance P and the healing of debrided corneal epithelium in mice.

Wakayama symposium: modulation of wound healing response in the corneal stroma by osteopontin and tenascin-C.

The extracellular matrix components osteopontin and tenascin-C are ligands of α9 integrin, and both play roles in corneal wound fibrosis and neovascularization. It has been shown that loss of osteopontin impairs closure of incisional wounds in the mouse cornea. Detailed analyses suggest that the loss of osteopontin reduces macrophage invasion and myofibroblast differentiation in the healing stroma in association with suppression of fibrogenic gene expression in response to injury. Cultured ocular fibroblasts derived from knockout mice showed an impairment of activation of p38 MAPK and Smad3 upon exposure to transforming growth factor ß1. The loss of tenascin-C delays stromal healing in association with suppression of fibrogenic gene expression and macrophage invasion. With regard to neovascularization, the loss of either osteopontin or tenascin-C suppressed the growth of new blood vessels from the limbal region toward the central cornea in response to corneal cauterization in mice. Gene expression analysis further showed that lack of osteopontin or tenascin-C resulted in inhibition of angiogenic and proinflammatory gene expression. In conclusion, osteopontin or tenascin-C, α9 integrin ligands, play an important role in stromal healing (or fibrosis) and neovascularization in mouse cornea.

TRPV1 involvement in inflammatory tissue fibrosis in mice.

We examined whether absence or blocking of transient receptor potential vanilloid subtype 1 (TRPV1) affects the level of inflammation and fibrosis/scarring during healing of injured tissue using an alkali burn model of cornea in mice. A cornea burn was produced with 1 N NaOH instilled into one eye of TRPV1-/- (KO) (n = 88) or TRPV1+/+ (n = 94) mice. Examinations of the corneal surface and eye globe size suggested that the loss of TRPV1 suppressed inflammation and fibrosis/scarring after alkali burn, and this was confirmed by histology, IHC, and gene expression analysis. The loss of TRPV1 inhibited inflammatory cell invasion and myofibroblast generation in association with reduction of expression of proinflammatory and profibrogenic components. Experiments of bone marrow transplantation between either genotype of mice showed that KO corneal tissue resident cells, but not KO bone marrow-derived cells, are responsible for KO-type wound healing with reduced inflammation and fibrosis. The absence of TRPV1 attenuated expression of transforming growth factor ß 1 (TGFß1) and other proinflammatory gene expression in cultured ocular fibroblasts, but did not affect TGFß1 expression in macrophages. Loss of TRPV1 inhibited myofibroblast transdifferentiation in cultured fibroblasts. Systemic TRPV1 antagonists reproduced the KO type of healing. In conclusion, absence or blocking of TRPV1 suppressed inflammation and fibrosis/scarring during healing of alkali-burned mouse cornea. TRPV1 is a potential drug target for improving the outcome of inflammatory/fibrogenic wound healing.

Two cases of congenital retrobulbar cyst or peripapillary staphyloma with an alcoholic mother.

The authors report two cases of congenital retrobulbar cyst or large peripapillary staphyloma with alcoholic mothers. In the first case, a 53-day-old newborn was referred for evaluation of microphthalmia in her left eye. Ophthalmic examination showed microcornea, microphthalmia, and an abnormally enlarged optic disc with an excavation in her left eye. Imaging revealed the presence of a cystic lesion in her left orbit that seemed to be communicated with the vitreous cavity. She did not have chromosomal abnormality. In the second case, a large peripapillary staphyloma was detected in the right eye of a 7-month-old newborn. The mother of each patient was an alcoholic. Retrobulbar cystic lesion or peripapillary staphyloma could be considered to be a series of abnormalities caused by the degree of the failure of the optic cup. Effects of each mother's alcohol intake on the development of the eye, especially the closure of the optic cup, is to be further investigated.

Histopathological features in a case of peters' anomaly with acquired corneal staphyloma.

We report a case of corneal staphyloma histologically diagnosed as caused by Peters' anomaly. A 62-year-old male had a protruding opaque vascularized cornea that began to bulge from six months ago in the right eye. Since his right eye was blind and he wanted us to remove the eyeball for cosmetic improvement, we enucleated the affected eye. The enucleated tissue was fixed in formalin and embedded in paraffin for histological examination. Hematoxylin and eosin staining showed that the cornea lacked the posterior part of the corneal stroma and Descemet's membrane in the central region and the entire corneal endothelium. The corneal epithelium was keratinized. Collagen type I was strongly positive in peripheral cornea and weakly in protruding stroma. The cells labeled by antibodies against αSMA were scattered in the entire corneal stroma. As judged by the histological findings, the eye with the central corneal staphyloma was diagnosed as Peters' anomaly.

Transforming growth factor beta signal transduction: a potential target for maintenance/restoration of transparency of the cornea.

Maintenance of the transparency and regular shape of the cornea are essential to the normal vision, whereas opacification of the tissue impairs vision. Fibrogenic reaction leading to scarring in an injured cornea is characterized by appearance of myofibroblasts, the key player of the fibrogenic reaction, and excess accumulation of fibrous extracellular matrix. Inflammatory/fibrogenic growth factors/cytokines produced by inflammatory cells play a pivotal role in fibrogenic response. Signaling systems involved in myofibroblast formation and fibrogenesis are activated by various growth factors, i.e., transforming growth factor beta or others. Modulation of transforming growth factor beta signal transduction molecules, e.g., Smad and mitogen-activated protein kinases, by gene transfer and other technology provides a new concept of prevention/treatment of unfavorable fibrogenesis in the cornea.

Neurotrophic keratopathy; its pathophysiology and treatment.

Neurotropic keratopathy is one of the major refractory corneal disorders, which was first recognized in 1824. This category of diseases is caused by damage to the trigeminal nerve and the consequent loss of corneal sensation. It leads to various types of corneal disorder, including superficial keratopathy, persistent epithelial defects and corneal ulcers. In the present article, we review the pathobiology and prevention/treatment of neurotrophic corneal diseases. The goals of treatment of neurotrophic keratopathy are to prevent the progression of corneal damage to promote epithelial healing in case that the original damage in the trigeminal nerve or its braches is difficult. The therapy should be prompt and based on the clinical stage of the disease. Although at present, there are no accurate treatment methods for neurotrophic keratopathy, several effective treatments have been reported. Signals derived from TRP channels are involved in homeostasis of tissues by controlling cell behaviors, i. e., gene expression for inflammation, cell migration, or cell survival/cell death. Targeting TRP channel in the cornea is expected to contribute to the development of a new treatment method for neurotrophic keratopathy. Further study and clinical trial are need to establish this new treatment strategy.

Immunohistochemical observation of anterior subcapsular cataract in eye with spontaneously regressed retinoblastoma.

We report the histological findings of secondary cataract in an eye with a spontaneously regressed retinoblastoma to obtain keys to clarify the mechanism of this phenomenon. During phacoemulsification, opacified anterior capsule was obtained, fixed in formalin, and embedded in paraffin. Paraffin sections of the specimen were histologically observed. Hematoxylin-eosin staining showed extracellular matrix accumulation in the extracted fibrous anterior subcapsular opacification. Immunohistochemistry revealed the presence of fibrous collagen types and cellular fibronectin. Presumed lens cells amid matrix were positively labeled for vimentin, alpha-smooth muscle actin, and phospho-Smad2. Histology of the fibrous anterior subcapsular opacification tissue showed the possibility of epithelial-mesenchymal transition of the lens epithelial cells in the secondary cataract following a spontaneously regressed retinoblastoma.

Therapeutic potential of trichostatin A to control inflammatory and fibrogenic disorders of the ocular surface.

PURPOSE: To examine the effects of a histone deacetylase inhibitor, Trichostatin A (TSA), on the behavior of macrophages and subconjunctival fibroblasts in vitro and on ocular surface inflammation and scarring in vivo using an alkali burn wound healing model. METHODS: Effects of TSA on expression of inflammation-related growth factors or collagen I were examined by real-time RT-PCR or immunoassay in mouse macrophages or human subconjunctival fibroblasts. Effects of TSA on trans forming growth factor ß (TGFß)/Smad signaling were evaluated with western blotting and/or immunocytochemistry. Alkali-burn injuries on the eyes of mice were performed with three µl of 0.5 N NaOH under general and topical anesthesia. TSA (600 µg/Kg daily) or vehicle was administered to animals via intraperitoneal (i.p.) injection. Histology and real-time RT-PCR investigations evaluated the effects of TSA on the healing process of the cornea. RESULTS: TSA inhibited TGFß 1 and vascular endothelial growth factor (VEGF) expression in macrophages, and TGFß1 and collagen I in ocular fibroblasts. It elevated the expression of 5'-TG-3'-interacting factor (TGIF) and Smad7 in fibroblasts and blocked nuclear translocation of phospho-Smad2. Real-time PCR and immunocytochemistry studies showed that systemic administration of TSA suppressed the inflammation and fibrotic response in the stroma and accelerated epithelial healing in the alkali-burned mouse cornea. CONCLUSIONS: Systemic administration of TSA reduces inflammatory and fibrotic responses in the alkali-burned mouse ocular surface in vivo. The mechanisms of action involve attenuation of Smad signal in mesenchymal cells and reduction in the activation and recruitment of macrophages. TSA has the potential to treat corneal scarring in vivo.

JNK MAPK signaling contributes in vivo to injury-induced corneal epithelial migration.

PURPOSE: Injury-mediated corneal epithelial wound healing in vivo is mediated through different cell signaling pathways depending on whether or not the basement membrane is removed. Given this dependence, we ascertained if c-jun N-terminal kinase (JNK/SAPK) mitogen-activated protein kinase (MAPK) cell signaling mediates this response in vivo and in vitro, irrespective of the presence or absence of the basement membrane. Furthermore, in vitro the relative contribution was determined by the JNK/SAPK pathway to that of its p38 and ERK MAPK counterparts in mediating injury-induced increases in cell migration. METHODS: Corneal epithelial debridement was performed in C57BL/6 mice and their organ-cultured eyes without removal of the basement membrane. In rabbits, following basement membrane removal by keratectomy, fluorescein-staining monitored reepithelialization was performed as in the mice. Immunohistochemistry evaluated changes in JNK phosphorylation status and localization. JNK inhibitor I and its inactive analogue determined if JNK signaling activation contributes to wound healing. BrdU staining assessed cell proliferation. A scratch wound assay of healing rates in SV40-immortalized human corneal epithelial cell line (HCEC) evaluated the relative contributions by p38 and ERK and JNK MAPK signaling activation to wound healing. A TUNEL assay probed for apoptosis after wound closure of HCEC. MTT assay evaluated corneal epithelial viability. RESULTS: Two hours following mice corneal epithelial debridement, phospho-JNK was transiently upregulated in the nucleus, whereas total JNK was constitutively expressed. JNK inhibitor I suppressed epithelial spreading in organ-cultured mouse eyes and rabbit corneal blocks, irrespective of the presence or absence of basement membrane. No proliferation was detected at the wound edges. In HCEC, a p38 (SB203580) and a JNK pathway inhibitor (JNK inhibitor I) inhibited migration rates more than U0126-induced ERK, whereas the JNK inhibitor I inactive analogue had no effect. JNK pathway inhibition wound closure in this region was not associated with either any TUNEL or BrdU-positive cells. Cell viability was unaffected by any of these MAPK inhibitors. CONCLUSION: JNK/SAPK pathway activation stimulates wound healing in vitro and in vivo, irrespective of the presence or absence of the basement membrane. Therefore, studies on how wound closure is elicited in HCEC are relevant for identifying how MAPK signaling mediates this response in vivo and in organ-cultured eyes. This realization suggests that the JNK signaling system has a role in vivo that is intermediate to those of ERK and p38 in mediating increases in cell migration.

TGF beta in fibroproliferative diseases in the eye.

Transforming growth factor b (TGF beta) is believed to be the most important ligand in the pathogenesis of fibrotic diseases in the eye. Such ocular fibrotic diseases include scarring in the cornea and conjunctiva, fibrosis in the corneal endothelium, post-cataract surgery fibrosis of the lens capsule, excess scarring the tissue around the extraocular muscles in the strabismus surgery and proliferative vitreoretinopathy. In the proliferative stage of diabetic retinopathy, fibrogenic reaction causes tractional retinal detachment in association with contraction of the tissue. A myofibroblast, the major cellular component in the fibrotic lesions, is derived from both mesenchymal cells (in cornea and conjunctiva) and epithelial cell types (lens or retinal pigment epithelium or corneal endothelium) through epithelial-mesenchymal transition (EMT). The myofibroblasts cause excess accumulation of fibrogenic extracellular matrix with resultant tissue contraction and impaired functions. Although various cytokine signaling pathways are involved in the fibrogenic reaction in tissues, TGF beta/Smad signal is the critical one. Blocking Smad signal by chemical or natural inhibitors or anti-Smad gene introduction effectively suppress fibrogenic reaction; inhibition of both fibroblast-myofibroblast conversion or EMT. Such strategies can be clinically tested.