1,25（OH）₂D3 Prevent High Glucose-induced Retina Microvascular Endothelial Cells Dysfunction Through Inhibition Of NLRP3 Inflammasome Activation

ObjectiveDiabetic retinopathy is a serious diabetes complication which shown an increase in vascular permeability and the breakdown of the blood retinal barrier and eventually lead to hemorrhage and exudation. Although landmark cross-sectional studies have confirmed the strong relationship between chronic hyperglycaemia and the development and progression of diabetic retinopathy the underlying mechanism of how hyperglycaemia causes retinal microvascular damage remains unclear. Therefore,to find the mechanism of retina microvascular endothelial cells dysfunction is necessary. Except for its traditional function of controling of calcium and phosphorus,vitamin D3 has a lot of biological effects in many other effects. In our study, we research the link between vitamin D3 and retina microvascular endothelial cells function, whether vitamin D3 have a protective effect on retina microvascular endothelial cells dysfunction as well as its possible mechanisms under high glucose by animal experiments and cell experiments.MethodsAnimal experiments: The rats were then randomized into three groups for the5-week experiment and given treatment as follows:(1) normal(nondiabetic) rats,(2)diabetic rats(3) diabetic rats treated with vitamin D3 intervention(233.3U/kg/wk)during the last 5 weeks,Rats were categorized as diabetic when blood glucose exceeded 16.7mmol/L at 48 h after intraperitoneal administration with 60mg/kg streptozotocin. Proteins levels of NLRP3 in the retinal tissues were determined by western blotting immunohistochemisty and immunofluorescence.Cell experiments: In vitro, HRMECs cells are incubated in two glucoseconcentrations:5.6mmol/L and 30mmol/L for 48 hours and divided into control group(Ctr), control plus VD group(Ctr+VD), High-glucose group(HG) and High-glucose plus VD group(HG+VD). We analyze 1,25(OH)2D3 on apoptosis,reactive oxygen species(ROS) generation, and further explore its possible pathway.ResultsAnimal experiments: Compared with the healthy rats, DM rats showed a significantly increased damage in Blood Retinal Barrier and retinal structure,but vitamin D3 intervention can reduce this tendency as well as down-regulate the protein levels of NLRP3.Cell experiments: in vitro, 1,25(OH)2D3 can significantly down-regulate ROS production and apoptosis in HRMECs which are incubated in high glucose.1,25(OH)2D3 also reduce high glucose induced NLRP3 inflammasome expression and decrease expression of ASC,TXNIP and IL-1β at the same time.Conclusion1. Vitamin D3 can significantly protect retina microvascular function and deceased expression of NLRP3 in retina.2. 1,25(OH)2D3 prevent high glucose induced HRMECs cell apoptosis and oxidative stress by blocking NLRP3 inflammasome.