ADHESION OF HUMAN TRABECULAR MESHWORK CELLS TO EXTRACELLULAR-MATRIX PROTEINS - ROLES AND DISTRIBUTION OF INTEGRIN RECEPTORS

Purpose, To examine the adhesion of human trabecular meshwork cells wi th various extracellular matrix (ECM) proteins and to evaluate the rol es and distribution of integrin receptors. Methods. Cultured human tra becular meshwork cells were added to 96-well plates either uncoated or coated with proteins including fibronectin, laminin, and vitronectin, as well as collagen types I, III, IV, V, and VI. After incubation for 1 hour, the adhesion of cells was measured. Expression of cell surfac e integrins was determined by cell enzyme-linked immunoadsorbent assay (ELISA) and immunoprecipitation. Distribution was visualized by immun ofluorescence staining using integrin-specific antibodies. For functio n perturbation and peptide inhibition studies, cells were preincubated with either integrin antibodies or synthetic peptides before the adhe sion assays. Results. Human trabecular meshwork cells attached to plat es coated with ECM proteins in a dose-dependent manner. Fibronectin, v itronectin, and collagen types I and IV were the preferred ECM substra tes. Cell ELISA revealed the presence of integrins alpha 1, alpha 2, a lpha 3, alpha 4, alpha 5, alpha 6, alpha v, beta 1, beta 3, beta 5, al pha 5 beta 1, and alpha v beta 3 and the absence of beta 2 and beta 4 on human trabecular meshwork cells. Results from immunostaining experi ments were consistent with those from cell ELISA studies. Attachment o f cells to ECM proteins was blocked by specific integrin antibodies. C ell adhesion To fibronectin and vitronectin was inhibited by peptides containing the Arg-Gly-Asp sequence. Conclusions. Extracellular matrix proteins mediate the adhesion of human trabecular meshwork cells in c ulture. Integrin receptors appear to have functional roles in the cell -matrix interactions.