Purpose: To examine the expression of integrin receptors in the human trabecular meshwork.
Methods: The expression of integrins in human tissues was visualized by immunohistochemical staining using integrin-specific antibodies. Immunoprecipitation was performed after biotin labeling of cell surface proteins. Reverse transcriptase-polymerase chain reaction was used to detect the presence of mRNA species for integrin subunits.
Results: Human trabecular meshwork tissues obtained from donors 2 to 65 years old stained positively for integrins alpha1, alpha3, alpha4, alpha5, alpha6, alphav, beta1, beta3, beta4 and beta5. The staining was observed mostly around the edges of trabecular beams in association with trabecular meshwork cells. The staining intensity did not appear to vary with donor age. In addition, immunoprecipitation of tissue extracts revealed the presence of integrin alpha2 and confirmed the absence of beta2. Results from polymerase chain reactions were consistent with these findings.
Conclusions: A spectrum of integrin receptors that may have important roles in the cell-matrix interactions are demonstrated in the human trabecular meshwork. The repertoire identified in tissues is similar to that found in cultured cells except that the beta4 expression in tissues is lost in cultures.