transforming-growth-factor-beta and Corneal-Edema

To assess the role of the transforming growth factor (TGF)ss system in formation of corneal haze after excimer laser photorefractive keratectomy (PRK), levels of mRNAs for three TGFss isoforms (TGFss1, TGFss2, and TGFss3), the TGFss type II receptor (TssRII), and extracellular matrix (ECM) genes including fibronectin (FN), collagen I, collagen III, and collagen IV were measured in rat corneas.. Corneas were graded for corneal haze at 0, 1.5, 7, 21, 42, and 91 days after PRK. Total RNA was isolated from pooled corneas, and the levels of mRNAs were measured using competition-based quantitative reverse transcription-polymerase chain reaction (RT-PCR).. Severe corneal haze developed by day 42 and persisted to day 91. Levels of TGFss1 mRNA were high in rat corneas before PRK and remained relatively constant. In contrast, levels of TGFss2 and TGFss3 mRNAs were very low in normal corneas, increased 300-fold and 25-fold, respectively, on day 21, and remained elevated on day 91. Levels of mRNA for TssRII increased, with a peak elevation of 50-fold on day 42 after PRK. Levels of mRNAs for ECM proteins also increased. Fibronectin mRNA was nondetectable in normal corneas but rapidly increased to 675 copies/cell on day 7 and remained elevated to day 91. Collagen III mRNA levels peaked on day 21 with a 700-fold increase compared with a very low level of expression in normal cornea, and then decreased on day 91. Expression of collagen I mRNA lagged expression of collagen III mRNA and peaked at day 42 after PRK with a 1200-fold increase over normal cornea. In contrast, mRNA for collagen alpha(1)IV, a major component in basement membranes, remained relatively stable through day 21 and then increased slightly on days 42 and 91.. The synchronized increase in mRNA synthesis for both the TGFss system and key ECM genes supports the hypothesis that TGFss is a key growth factor promoting stromal haze formation in corneas after PRK and suggests that limiting TGFss system may reduce corneal scarring after excimer laser ablation.

Topics: Animals; Cornea; Corneal Edema; Corneal Opacity; DNA Primers; Extracellular Matrix Proteins; Eye Proteins; Gene Amplification; Gene Expression; Lasers, Excimer; Male; Photorefractive Keratectomy; Protein Isoforms; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger; Transforming Growth Factor beta; Wound Healing

Accumulating evidence suggests the involvement of TGF-beta in the process of corneal opacity, which is one of the serious causes of visual loss. However, whether TGF-beta is indeed critical for the pathogenesis remains unknown. We constructed an adenovirus expressing an entire ectodomain of the human type II TGF-beta receptor fused to Fc portion of human IgG (AdTbeta-ExR): this soluble receptor is secreted from AdTbeta-ExR-infected cells, binds to TGF-beta and inhibits TGF-beta signaling. When AdTbeta-ExR was injected into the femoral muscle of Balb/c mice, a high level of the soluble receptor protein (2.0-3.5 x 10(3) pM) was detectable in the serum and in the ocular fluid for at least 10 days. In the mice subjected to corneal injury with silver nitrate and to intramuscular injection with either saline or a control adenovirus expressing beta-galactosidase (AdLacZ), corneal opacification composed of extracellular matrix (ECM) accumulation, of infiltration of neutrophils and monocytes/macrophages, and of angiogenesis were all induced. In contrast, they were markedly reduced in the mice injected with AdTbeta-ExR. Immunohistochemical analysis revealed that TGF-beta, fibronectin, macrophage chemoattractant protein-1, and vascular endothelial growth factor were densely stained in the edge of wounded cornea, but they were scarcely present in the injured-cornea of AdTbeta-ExR-treated mice. Our results demonstrate that TGF-beta indeed plays a critical role in the process of cornea opacification, and that adenovirus-mediated expression of a soluble TGF-beta receptor can be therapeutically useful.

Topics: Adenoviridae; Animals; Chemokine CCL2; Cornea; Corneal Edema; Corneal Opacity; Endothelial Growth Factors; Fibronectins; Flow Cytometry; Gene Expression; Genetic Therapy; Genetic Vectors; Humans; Immunohistochemistry; Injections, Intramuscular; Lymphokines; Macrophages; Mice; Mice, Inbred BALB C; Neovascularization, Pathologic; Neutrophils; Receptors, Transforming Growth Factor beta; Recombinant Fusion Proteins; Transfection; Transforming Growth Factor beta; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

The goal was to compare the biological response of the corneal stroma with three porous materials: a melt blown microfibre web of polybutylene:polypropylene (80:20); a polyester spun laced fabric (polyethylene terephthalate), and an expanded polytetrafluoroethylene. Fifty per cent of each of the materials were modified using argon radio frequency.. Discs (6 mm in diameter) were inserted into interlamellar stromal pockets and followed for a period of 12 weeks. Clinical evaluations were performed weekly. At 6 and 12 weeks, fibroplasia and the distribution of matrix proteins and growth factors (bFGF and TGF-beta) were evaluated immunohistochemically. The characterisation of glycosaminoglycans was determined after selective extraction and digestion.. The response to the disc resembled that of a wound with a decrease in keratan sulphate and an increase in dermatan sulphate. Pretreatment of the disc reduced corneal oedema and neovascularisation. Heparan sulphate, not normally detected in the corneal stroma, was detected in the region immediately surrounding the disc and in the discs of some materials. The presence of glycosaminoglycans and collagens in the disc indicated that cells had migrated into the disc and deposited a complex matrix in all three materials. The collagen response was not surface specific. bFGF and TGF-beta were detected in the region between the disc and the stroma in the polybutylene material and became diffuse with time.. Fibroplasia occurred most rapidly into the polyester discs but was accompanied by a large number of inflammatory cells. While the distribution of collagens was not altered by the material, the expression and distribution of growth factors was material dependent. bFGF was expressed transiently and occurred before that of TGF-beta. It is predicted that the transient expression of growth factors mediates the regulation of matrix proteins.

Topics: Animals; Collagen; Cornea; Corneal Edema; Corneal Transplantation; Fibroblast Growth Factor 2; Glycosaminoglycans; Implants, Experimental; Polyenes; Polyethylene Terephthalates; Polypropylenes; Polytetrafluoroethylene; Porosity; Postoperative Complications; Prostheses and Implants; Rabbits; Transforming Growth Factor beta