Heterogeneity of Type I Collagen Expression in Human Corneal Keratoconus Fibroblasts

Abstract

Corneal fibroblast cultures were established from 3 normal and 4 keratoconus (KC) corneas. Type I collagen protein synthesis and steady-state RNAs were analyzed in these cultures by metabolic labeling studies, slot blots and immunofiuorescent microscopy. Type I collagen proteins and steady-state RNAs were reduced in cells from 3 of the 4 KC cultures when compared with normal fibroblasts, suggesting that collagen expression is heterogenous in KC and that the heterogeneity is expressed at the cellular and molecular level. The type I collagen matrix synthesized by the KC fibroblasts appeared normal when analyzed by immunofluorescence, suggesting that the incorporation of type I collagen into the extracellular matrix is not affected in KC fibroblasts.

Systematically Displaying the Pathogenesis of Keratoconus via Multi-Level Related Gene Enrichment-Based Review

“…The top differentially expressed genes based enrichment were similar to the GOs at the genomic level, mainly including ECM and its related GO terms, response to inflammatory and various bindings. These results represent further confirmation of the importance of collagen ( 61 , 67 , 75 , 78 , 84 , 87 , 88 , 113 , 117 , 125 , 163 – 165 ), ECM ( 76 , 90 , 97 , 158 ), cell adhesion ( 72 , 97 ), and inflammatory ( 49 , 101 , 124 , 128 , 139 , 204 ) in the pathogenicity of KC. In addition, cell proliferation, angiogenesis, and response to drug have not been reported before, which may be involved in the process of KC, and should be investigated further.…”

“…After an initial search, a total of 946 reported differentially expressed proteins between KC corneas and normal corneas were collected ( 98 – 103 , 109 , 114 , 117 , 118 , 120 , 125 , 126 , 128 , 130 , 131 , 133 , 137 – 193 ). Immunohistochemistry, immunofluorescence, and western blot were used for candidate protein level detection, and proteomic analysis was performed via mass spectrometry.…”

“…These genetic changes, together with the aforementioned stimulation, lead to the changes in related functions and pathways in the corneal cells. The related functions include the response to the stimulation of hormones and reactive oxygen species ( 96 , 106 , 120 , 121 , 189 ), activation and positive regulation of various signaling (MAPK activity, NF-kappaB activity, and I-kappaB kinase/NF-kappaB signaling) ( 123 , 128 ), upregulation of cytokines and collagen-related enzymes ( 49 , 101 , 122 , 124 , 147 , 174 , 187 ), and downregulation of collagen, collagen-crossing, and other ECM-related proteins ( 97 , 103 , 117 , 163 , 164 ), and regulation of apoptosis ( 36 , 175 , 186 ). These undoubtedly lead to the reduction of extracellular components and the induction of apoptosis and aging.…”

Cellular Incursion into Bowman's Membrane in the Peripheral Cone of the Keratoconic Cornea

“…Radda et al (1982) found a 5 % increase in type I collagen in keratoconus, while Zimmermann et al (1988) found no differences in collagen composition of biochemical extracts from keratoconus. Analysis of expression of collagens by keratocytes in cell culture further clouds the issue: Newsome et al (1981) stated that collagen types I and III were synthesized in similar amounts by both normal and keratoconic derived stromal cells, while Peters et al, (1993) analysed four cultures of keratoconic cells and found that type I collagen and steady-state RNAs were reduced in cells from three of the four cultures. The answer to these apparent anomalies may lie in the work of Yue et al, (1985).…”