Effect of fibrostatin C, an inhibitor of prolyl 4-hydroxylase, on collagen secretion by human Tenon's capsule fibroblasts in vitro

Force Matters: Biomechanical Regulation of Cell Invasion and Migration in Disease

Atherosclerosis, cancer, and various chronic fibrotic conditions are characterized by an increase in the migratory behavior of resident cells and the enhanced invasion of assorted exogenous cells across a stiffened extracellular matrix (ECM). This stiffened scaffold aberrantly engages cellular mechanosignaling networks in cells, which promotes the assembly of invadosomes and lamellae for cell invasion and migration. Accordingly, deciphering the conserved molecular mechanisms whereby matrix stiffness fosters invadosome and lamella formation could identify therapeutic targets to treat fibrotic conditions, and reducing ECM stiffness could ameliorate disease progression.

Safety and efficacy of using off-label bevacizumab versus mitomycin C to prevent bleb failure in a single-site phacotrabeculectomy by a randomized controlled clinical trial

PURPOSE

To analyze the safety and efficacy of bevacizumab (1.25 mg/0.05 mL) versus 0.03% mitomycin C (MMC) for preventing bleb failure in patients undergoing single-site phacotrabeculectomy for primary open-angle glaucoma or chronic angle-closure glaucoma.

MATERIALS AND METHODS

Thirty-eight consecutive patients with visually significant cataract and coexistent primary open-angle glaucoma or chronic angle-closure glaucoma were randomized into 3 groups. One group received conventional 0.03% MMC (n=13); the second group received 3 subconjunctival injections of bevacizumab (1.25 mg in 0.05 mL) (n=13); and the third group received bevacizumab soaked in sponges (1.25 mg in 0.05 mL) (n=12) intraoperatively on the sclera. Patients were followed up for 6 months. The primary outcome measure was treatment success and bleb morphology in the study eye at 6-month follow-up.

RESULTS

All 3 groups showed significant reduction in mean intraocular pressure at 1 week after treatment, which was maintained at 6 months. However, the subconjunctival bevacizumab group had 90% patients with complete success as opposed to 60% in each of the other 2 groups (P=0.04). In both bevacizumab groups, bleb vascularity increased progressively over the 6-month follow-up. One patient in the subconjunctival bevacizumab group showed a local conjunctival necrosis.

CONCLUSION

In this pilot study with a small number of subjects, short-term outcomes suggest that subconjunctival bevacizumab is equally effective in reducing intraocular pressure with a better safety profile compared with MMC in the dosing schedule studied. However, bevacizumab soaked in a sponge appears to have no advantages over MMC. Subconjunctival bevacizumab may be a useful agent for improving success and for limiting scar tissue after phacotrabeculectomy.

Connective tissue growth factor modulates extracellular matrix production in human subconjunctival fibroblasts and their proliferation and migration in vitro

PURPOSE

We examined the role of connective tissue growth factor (CTGF) in transforming growth factor beta1 (TGFbeta1)-related behavior in cultured human subconjunctival fibroblasts (SCFs), protein production, mRNA expression of CTGF and type I collagen alpha1 chain (colIA1), and cell proliferation and migration. TGFbeta1 is the major factor involved in bleb scarring following filtration surgery.

METHODS

An antisense deoxynucleotide (antisense) (5 microM) for CTGF mRNA was used to block endogenous CTGF expression. Effects of antisense on extracellular matrix (ECM) production and immunolocalization, mRNA expression, and cell proliferation and migration were examined in human SCF cultures with or without TGFbeta1 (5 ng/ml). Cell migration was examined in an in vitro wound model of monolayer fibroblast cultures.

RESULTS

CTGF antisense reduced mRNA expression of CTGF and colIA1 and production of the ECM components type I collagen, and fibronectin much more markedly in cells treated with TGFbeta1 compared with control fibroblasts, and it inhibited the proliferation of cultured SCFs to 71.9% of that of controls after 13 days of culture. CTGF antisense also delayed defect closure in monolayer cell sheets. In the culture, the defect was closed by TGFbeta1 by 36 h, whereas 7.0% of the defect remained at 48 h in the antisense-treated culture.

CONCLUSIONS

These findings indicate that CTGF is involved in ECM production in SCFs activated by exogenous TGFbeta1 in vitro. Inhibition of CTGF expression may be effective in preventing undesirable scar formation during healing following filtration surgery.

Modulation of wound healing during and after glaucoma surgery

Following all types of glaucoma filtration surgery (GFS), scarring still poses the major threat to long-term success. The healing and scarring determine the percentage of patients achieving low final intraocular pressures (IOPs) that are associated with virtually no glaucoma progression. The use of antifibrotic agents to inhibit scarring of trabeculectomy blebs is now a well-established clinical practice. Unfortunately, severe complications such as leakage, infection, hypotony, and endophthalmitis with complete loss of vision may occur. In addition, surgery still fails in some individuals despite maximal doses of current antifibrotics. Better therapeutic agents are needed. Many promising new agents are being evaluated clinically and in vitro. In this chapter, we will discuss our current understanding of the wound healing process after glaucoma surgery and promising new treatment modalities.

Genipin Suppresses Subconjunctival Fibroblast Migration, Proliferation and Myofibroblast Transdifferentiation

PURPOSE

Inchin-ko-to is a herbal medicine which has therapeutic effects in ameliorating liver fibrosis or cholestatic liver diseases. Its main bioactive component is genipin, which is an intestinal bacterial metabolite of this medication. Accordingly, we determined whether or not Inchin-ko-to suppresses in a wound healing model subconjunctival fibroblast (SCF) migration proliferation and myofibroblast transdifferentiation since an inhibitory effect could be of value in improving trabeculotomy outcome.

METHODS

Effects of genipin on SCF cell migration were examined subsequent to wounding confluent monolayer cultures. Alamar blue staining evaluated the effects of genipin (0-50 microg/ml) on fibroblast cell proliferation. Immunostaining determined alpha-smooth muscle actin (alphaSMA) expression. Western blotting evaluated (alphaSMA) expression and phospho-Smad2 formation. Real-time RT-PCR evaluated TGFbeta1 and collagen Ialpha2 mRNA expression. Enzyme-immunoassay determined culture medium collagen I content.

RESULTS

Genipin suppressed wound-induced cell migration and proliferation. It also decreased collagen type I TGFbeta1 and alphaSMA mRNA and protein expression. Smad2 signaling was inhibited by genipin in a dose-dependent manner.

CONCLUSION

Genipin suppresses injury-induced fibrogenic responses in SCFs. This result suggests that the herbal medicine Inchin-ko-to might have therapeutic value following trabeculotomy.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Immunolocalization of prolyl 4-hydroxylase in rabbit lens epithelial cells

PURPOSE

To localize the enzyme prolyl 4-hydroxylase in the crystalline lens and determine the ability of lens epithelial cells (LECs) to synthesize procollagen.

SETTING

Research laboratory, Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan.

METHODS

Phacoemulsification and aspiration of the crystalline lens followed by implantation of a poly(methyl methacrylate) intraocular lens (IOL) were performed in 1 eye each of 6 albino rabbits; the eye was enucleated 1 or 2 months later. Crystalline lenses were also extracted from the eyes of 2 rabbits. These samples were processed for immunohistochemical detection of the alpha- and beta-subunits of prolyl 4-hydroxylase.

RESULTS

A monolayer of LECs was detected on the inner surface of the intact anterior capsule. Antibodies directed against both subunits of prolyl 4-hydroxylase reacted strongly to LECs proliferating on capsules with IOLs, whereas little or no reaction was observed in quiescent LECs or in the regenerated lenticular structure.

CONCLUSION

The presence of prolyl 4-hydroxylase in LECs proliferating on the inner surface of the lens capsule suggests that these cells are involved in the production of procollagen and fibrosis during capsular injury and repair. Suppression of prolyl 4-hydroxylase activity may prevent the capsule opacification that results from cataract removal and IOL implantation.

Immunolocalization of prolyl 4-hydroxylase subunits, alpha-smooth muscle actin, and extracellular matrix components in human lens capsules with lens implants

Lens capsules become fibrotic after the extraction of a cataract. To understand this phenomenon, we evaluated the immunolocalization of prolyl 4-hydroxylase (an enzyme involved in procollagen hydroxylation), and extracellular matrix components and cytoskeletal components in a normal human lens capsule and in others with intraocular lenses. Lens capsules containing intraocular lenses were removed from a patient with proliferative vitreoretinopathy and three with proliferative diabetic retinopathy during vitreous surgery. Two circular sections of the anterior capsules with lens epithelial cells were obtained by anterior capsulotomy during cataract surgery. In addition, a lens capsular bag was obtained immediately after phacoemulsification. The lens capsules were processed for light microscopic immunohistochemical detection of the alpha and beta subunits of prolyl 4-hydroxylase, extracellular matrix components (including collagen types, laminin and cellular fibronectin) or cytoskeletal components (such as cytokeratin, vimentin and alpha-smooth muscle actin). Monolayer lens epithelial cells were seen on the inner surface of the normal anterior capsules. Each intraocular lens was found to be fixed in the capsular bag. Light microscopic immunohistochemistry showed that these proliferating cells expressed vimentin and alpha-smooth muscle actin; in contrast, quiescent lens epithelial cells did not stain for alpha-smooth muscle actin. Marked immunostaining for subunits of prolyl 4-hydroxylase was detected in lens epithelial cells proliferating on the capsules, while no or only faint prolyl 4-hydroxylase immunoreactivity was detected in quiescent lens epithelial cells immediately after phacoemulsification. Collagen types I, III and VI and cellular fibronectin were observed diffusely in accumulated connective tissue on a capsule with an intraocular lens. Type IV collagen immunoreactivity was seen both in the capsules and in the connective tissue accumulation on the capsules. Collagen V and laminin were detected in association with cellular proliferation. Collagen VII and VIII and laminin 5 were not seen. We concluded that during wound healing of the lens capsule after cataract extraction, the lens epithelial cells that proliferate on the inner surface of the capsule transform it into a myofibroblastic phenotype, expressing prolyl 4-hydroxylase and alpha-smooth muscle actin. These proliferating cells are involved in the production of collagen on the lens capsule. This results in a postoperative fibrotic process and contraction of the lens capsule.