Müller Glia Co-Regulate Barrier Permeability with Endothelial Cells in an Vitro Model of Hyperglycemia

Diabetic retinopathy is a complex, microvascular disease that impacts millions of working adults each year. High blood glucose levels from Diabetes Mellitus lead to the accumulation of advanced glycation end-products (AGEs), which promote inflammation and the breakdown of the inner blood retinal barrier (iBRB), resulting in vision loss. This study used an in vitro model of hyperglycemia to examine how endothelial cells (ECs) and Müller glia (MG) collectively regulate molecular transport. Changes in cell morphology, the expression of junctional proteins, and the reactive oxygen species (ROS) of ECs and MG were examined when exposed to a hyperglycemic medium containing AGEs. Trans-endothelial resistance (TEER) assays were used to measure the changes in cell barrier resistance in response to hyperglycemic and inflammatory conditions, with and without an anti-VEGF compound. Both of the cell types responded to hyperglycemic conditions with significant changes in the cell area and morphology, the ROS, and the expression of the junctional proteins ZO-1, CX-43, and CD40, as well as the receptor for AGEs. The resistivities of the individual and dual ECs and MG barriers decreased within the hyperglycemia model but were restored to that of basal, normoglycemic levels when treated with anti-VEGF. This study illustrated significant phenotypic responses to an in vitro model of hyperglycemia, as well as significant changes in the expression of the key proteins used for cell-cell communication. The results highlight important, synergistic relationships between the ECs and MG and how they contribute to changes in barrier function in combination with conventional treatments.