epidermal-growth-factor and Glaucoma

The fibroblast is the central player in the wound repair and scarring processes that occur in the anterior segment of the eye. Glaucoma filtration surgery is the ultimate example of the importance of the wound healing process, as this process is the major determinant of the success of this procedure. We highlight the role of the fibroblast, and discuss some of the growth factors stimulating fibroblast proliferation, migration and extracellular matrix production in the wound environment. We also review current methods of suppressing fibroblast proliferation, the new concepts that have arisen from laboratory studies, and future directions of investigation and treatment.

Topics: Animals; Cell Division; Cell Movement; Depression, Chemical; Epidermal Growth Factor; Fibroblasts; Glaucoma; Humans; Transforming Growth Factor beta; Treatment Failure; Wound Healing

The techniques we developed to propagate HTM cells in serial cell culture have provided an opportunity to investigate the spectrum of endogenous PGs and other eicosanoids that are produced by these cells. PGE2 and PGF2 alpha were the major cyclooxygenase products detected by both radioimmunoassay and thin-layer chromatography. A small amount of 6-keto PGF1 alpha was also detected, indicating that these cells are able to produce prostacyclin. The observation of a substantial increase in the proportion of PGF2 alpha relative to PGE2 at later time periods after a media change suggests a metabolic conversion of PGE2 to PGF2 alpha by these cells. Bradykinin, thrombin, platelet activating factor, and serum were found to be effective stimulators of PG production by HTM cells, whereas calcium ionophore produced only a minor effect. Using high pressure liquid chromatography, elution profiles of radiolabeled metabolites of AA suggested the presence of certain lipoxygenase products, including LTB4, 12-HETE, 15-HETE, and a small amount of 5-HETE in HTM cells. The formation of these products was inhibited by both DEX and BW 755c, reinforcing the view that metabolic conversions of AA through the lipoxygenase pathway were possible in the trabecular meshwork. We also examined the effects of glucocorticoids on specific protein synthesis in the HTM cells, using 35S-methionine labeling and SDS-PAGE techniques. Short-term (1 day) DEX treatment revealed a major induction of a protein band at approximately 30 kDa. Longer treatments (1 to 3 weeks) resulted in major inductions at approximately 55 kDa inside the cells, with the presence of secreted forms (probably glycoproteins) between 55 and 72 kDa. The short-term DEX effect on protein synthesis a phospholipase inhibitor regulating eicosanoid production within the HTM. The longer-term induction may, on the other hand, be related more directly to the development of steroid glaucoma, based on our findings that the inductions of these proteins correlate with the observed time course and dose-dependence topical glucocorticoid effects on IOP. Continued in vitro and in vivo evaluations of the eicosanoid pathways in cultured HTM cells obtained from normal and glaucomatous human eyes may help to delineate their relationship to IOP regulation and the pathogenesis and treatment of glaucoma. Glucocorticoid-induced proteins may be key participants in the regulation of phospholipase activity and hence may represent a major control mechanism

Topics: Cells, Cultured; Dexamethasone; Eicosanoic Acids; Epidermal Growth Factor; Glaucoma; Glucocorticoids; Humans; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Time Factors; Trabecular Meshwork

Topics: Adult; Aged; Aging; Alcoholism; Amino Acids; Anesthetics, Local; Animals; Anti-Infective Agents; Anti-Inflammatory Agents; Aqueous Humor; Autonomic Nervous System; Biological Transport, Active; Brain Chemistry; Cardiac Glycosides; Catecholamines; Cell Differentiation; Central Nervous System; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Epidermal Growth Factor; Eye; Fibrinolysis; Glaucoma; Granuloma; Graves Disease; Hallucinogens; Humans; Hypertension; Immunity, Cellular; Infant; Infant, Newborn; Leukotriene B4; Metabolism, Inborn Errors; Multiple Sclerosis; Muscle Relaxation; Nutritional Physiological Phenomena; Oxygen; Oxygen Consumption; Pigment Epithelium of Eye; Pineal Gland; Prostaglandin Antagonists; Prostaglandins; Psychotropic Drugs; Retina; Retinal Degeneration; Serotonin; Smoking; SRS-A; Stress, Physiological; Water-Electrolyte Balance

Epidermal growth factor receptor (EGFR) is expressed in reactive astrocytes following injury in the CNS. However, the effects of activation of the EGFR pathway in astrocytes are not well established. In the present study, we demonstrate that activation of EGFR causes optic nerve astrocytes, as well as brain astrocytes, to form cribriform structures with cavernous spaces. Formation of the cribriform structures is dependent on new protein synthesis and cell proliferation. Platelet-derived growth factor and basic fibroblast growth factor were not effective. Smooth muscle cells and epithelial cells do not form cribriform structures in response to EGFR activation. The formation of the cribriform structures appears to be related to a guided migration of astrocytes and the expression of integrin beta1 and extracellular fibronectin in response to activation of EGFR. The EGFR pathway may be a specific, signal transduction pathway that regulates reactive astrocytes to form cavernous spaces in the glial scars following CNS injury and in the compressed optic nerve in glaucomatous optic nerve neuropathy.

Topics: Adult; Astrocytes; Cell Communication; Cell Division; Cell Movement; Cells, Cultured; Cicatrix; Cytoskeleton; Epidermal Growth Factor; ErbB Receptors; Extracellular Space; Fibronectins; Glaucoma; Humans; Integrin beta1; Middle Aged; Optic Disk

We have evaluated the 4q25-4q26 region where the autosomal dominant disorder Rieger syndrome has been previously mapped by linkage. We first excluded epidermal growth factor as a candidate gene by carrying out SSCP analysis of each of its 24 exons using a panel of seven unrelated individuals with Rieger syndrome. No evidence for etiologic mutations was detected in these individuals, although four polymorphic variants were identified, including three that resulted in amino acid changes. We next made use of two apparently balanced translocations, one familial and one sporadic, to identify a narrow physical localization likely to contain the gene or to be involved in regulation of gene function. Somatic cell hybrids were established from individuals with these balanced translocations, and these hybrids were used as a physical mapping resource for, first, preliminary mapping of the translocation breakpoints using known sequence tagged sites from chromosome 4 and then, after creating YAC and cosmids contigs encompassing the region, for fine mapping of those breakpoints. A cosmid contig spanning these breakpoints was identified and localized the gene to within approximately 150 kb of D4S193 on chromosome 4. The interval between the two independent translocations is approximately 50 kb in length and provides a powerful resource for gene identification.

Topics: Chromosome Mapping; Chromosomes, Human, Pair 4; Craniofacial Abnormalities; Epidermal Growth Factor; Genetic Markers; Glaucoma; Humans; Polymorphism, Single-Stranded Conformational; Sequence Analysis, DNA; Syndrome; Tooth Abnormalities; Translocation, Genetic; Umbilicus