Estradiol impacts Müller glia and endothelial cell responses in hyperglycemic microenvironments with advanced glycation end products

Diabetic retinopathy is a leading cause of vision loss in working adults, with disproportionate impact on women with lowered estrogen. Sex hormones and their receptors are significant to neuroprotection of the inner blood-retinal barrier (iBRB), a tissue that regulates transport across the neuroretina and vasculature. Moreover, high glucose levels in diabetes lead to the formation of advanced glycation end products (AGEs), which promote inflammation and iBRB breakdown to result in vision loss. This study examined the effects of supplemental estradiol on cell reactivity and cell barrier resistance within an in vitro model of hyperglycemia. Changes in morphology and expression of reactive oxygen species were examined when cells were exposed to a hyperglycemic medium containing AGEs, with and without supplemental estradiol. Cell morphology was assessed via changes in cell area and cell shape index, while intracellular ROS levels were measured using a ROS-sensitive dye. In addition, trans endothelial resistance (TEER) assays were used to measure changes in cell barrier function in response to hyperglycemic conditions, with and without supplemental estradiol. Results show that ROS levels in Müller glia in hyperglycemic conditions significantly decreased in response to supplemental estradiol. The estradiol further increased the resistivity of Müller glia and endothelial cell barriers cultured in high glucose and AGEs. This project illustrates the restorative effects of estradiol in collective responses of cell barriers formed by endothelial cells and Müller glia.