Expression des facteurs apoptotiques Bax et Bcl-2 dans la conjonctive des patients diabétiques : étude préliminaire

Abstract

Apoptosis, or programmed cell death, is necessary to multicellular organism survival, in contrast to involuntary necrosis that is devastating for tissue. It is positively or negatively regulated by proteins of the Bcl-2 family. The aim of our study was to analyze the expression of apoptotic factors Bax and Bcl-2 in the bulbar conjunctiva of diabetic patients without retinopathy and to compare it to the expression of these factors in nondiabetic patients. Twenty-five conjunctival biopsies were obtained from diabetic patients without retinopathy. The ocular fundus and retinal fluorescein angiography results were normal. Normal human conjunctiva was taken from 15 patients undergoing senile cataract surgery. Immunohistochemical analysis was performed using indirect immunoperoxidase with antibodies against Bax and Bcl-2. In the human diabetic conjunctiva, The Bax protein was highly expressed in all specimens (100%). It was distributed in epithelial cells, vascular endothelial cells, fibroblasts, and inflammatory cells. The Bcl-2 protein was always at a low level or absent. In normal conjunctiva, Bax showed a significant level, whereas Bcl-2 showed no trace of positivity. Bax is often localized in tissues characterized by an elevated rate of apoptosis; in contrast, Bcl-2 is absent in these places. Our results suggest that diabetic human conjunctiva, with its inflammatory and cicatricial phenomena, is a privileged target for apoptotic cell death.