Interleukin1‐Induced apoptosis of keratocytes: effect of biglycan

Abstract

Abstract Purpose: Biglycan is absent in the normal cornea, but UVR exposure leads to a significant expression of the biglycan gene in the rabbit cornea, an effect that decreases after healing is completed, indicating the envolvement of biglycan in the corneal repair process. In the present study, we have investigated possible involvement of biglycan in the modulation of the survival of keratocytes. Methods: Keratocytes were grown either under serum free conditions to obtain quiescent keratocyte cell culture or in the presence of 10% fetal bovine serum to induce keratocyte transformation into myofibroblasts. Myofibroblastic phenotype was confirmed by immunocytochemistry with anti‐alpha‐smooth muscle actin antibodies. Cell death was induced in both cell cultures by interleukin‐1 in the presence or absence of biglycan.Histone‐associated DNA fragments were assayed by using a cell death detection ELISA. Results: Quantification of histone‐associated DNA fragments by the cell death detection ELISA showed that biglycan strongly protected quiescent keratocytes from dying whereas it enhanced the death rate of transformed keratocytes. Apoptotic death rate was elevated after the addition of IL‐1 in both keratocyte and myofibroblast cell cultures. Co‐incubation with biglycan markedly reduced the number of apoptotic keratocytes but markedly increased the number of apoptotic myofibroblasts. Conclusions: IL‐1‐induces apoptosis of both quiescent and transformed keratocytes. However, biglycan has differential effect on apoptosis of these two cell types.