Localization of the cytoadhesin integrins in the human cornea

Abstract

Cell-matrix interactions play a fundamental role in normal and pathological conditions. They can be mediated by the cytoadhesin subgroup of the integrin superfamily of adhesion molecules. Its members include the vitronectin receptor (VNR) and the platelet glycoprotein IIb/IIIa (GP IIb/IIIa). Both receptors are composed of an alpha-chain (alpha v and alpha IIb, respectively) coupled to a beta 3-chain. Using in situ immunohistochemistry and monoclonal antibodies, the authors studied the distribution of GP IIIa (common beta 3-chain), GP IIb/IIIa (alpha IIb-chain) and VNR (alpha v-chain) in normal and pathological corneal tissues. In the normal cornea, the limbal vascular endothelium was weakly alpha v-positive. Occasionally, faint and granular staining was seen in the epithelium. In the pathological samples, an upregulated expression of the alpha v-chain was noticed on the corneal epithelium as well as on fibroblasts and corneal endothelium. The alpha IIb and beta 3-chains were consistently absent. These data suggest that expression of the VNR-alpha v-chain in the human cornea is modulated by soluble factors released during inflammation and wound healing. Dissociation of expression of the alpha v and beta 3-chains suggests usage of an alternative beta-chain by the VNR-alpha v-chain.

Integrins as Receptors for Extracellular Matrix Proteins in Human Cornea

“…The ligand specificity of the a6P4 complex is still unknown, but it appears to be a component of the hemidesmosome complex (Sonnenberg et al, 1991;Stepp et al, 1990). In contrast t o Lauweryns et al (1991) we found no immunoreactivity for a4 or a5 integrins in human corneal epithelium. The distribution of integrins in the cornea appears to differ from that of other stratified epithelia, at least in the presence of the a, integrin in the basal cells .…”

“…The expression of integrins in the epidermis (Peltonen et al, 1989; Klein et al, 1990), gingiva (Hormia et al, 1990) and cornea (Lauweryns et al, 1991; has been studied in detail. In all of these epithelia, the p,, a, and a3 subunits are found in basal and suprabasal cells throughout the cell membrane, most likely serving to mediate cell-cell interactions (Fig.…”

Biochemically and topographically engineered poly(ethylene glycol) diacrylate hydrogels with biomimetic characteristics as substrates for human corneal epithelial cells

“…The peptide RGD (Arg‐Gly‐Asp) is a rational first choice as the bioactive ligand to be incorporated into PEG hydrogels to provide specific and relevant adhesion moieties to the HCECs because this sequence is involved in binding to cell substrate adhesion receptors including several integrins 23. In the cornea, the epithelial basal cells are in direct contact with the BM and exhibit high expression levels of the RGD‐binding α 5 β 1 integrin,24 and corneal epithelial cells migrating across a wound express α 5 β 1 integrin at increased levels 25, 26. In wound healing experiments in vitro using HCECs, the wound closure rate increased from 2 μm/h in the absence of RGD up to 10 μm/h with 80% RGD content 27.…”

Why HLA-B27? My Thirty-Year Quest

“…12 My colleague Michael Davey and I have updated this speculation in an essay in Arthritis & Rheumatism. 13 The endotoxin-induced uveitis model has been useful for some of the initial publications on intraocular cytokines, 14,15 adhesion molecules, 16,17 complement, 18 and intracellular pathways 19 activated by a ligand for a toll receptor during inflammation within the eye. Like all animal models, however, this one has limitations.…”