Study Of Paeoniflorin Suppressed Matrix Metalloproteinase 9 Activation In Diabetic Retinopathy

Background:Diabetic retinopathy(DR)is a complication of diabetes,is the major cause of acquired blindness in the developed countries.Its pathological features include retinal cell apoptosis,retinal nerve dysfunction,and the large number of new blood vessels.Despite cutting-edge research in the field,the exact mechanism of this multifactorial disease remains elusive.Evidence has accumulated indicating that microglia within retinal plays a critical role in DR.Matrix metalloproteinases(MMPs)degrade extracellular matrix and play significant role in regulating intracellular homeostasis.Microglial matrix metalloproteinase 9(MMP-9)has an important role in destruction the integrity of blood-retinal barrier(BRB)associate with the development of DR.Paeoniflorin,a monoterpene glucoside,has a potent immunomodulatory effect on microglia.In this study whether paeoniflorin could significantly suppress microglial MMP-9 activation induced by high glucose and further relieve DR.Objective:To investigate the effects of paeoniflorin on the MMP-9 expression in diabetic retinopathyMethods:BV2 cells were used to investigate the effects and mechanism of paeoniflorin.Cell signaling was measured by western blot assay and immunofluorescence assay;High glucose stimulated microglia,simulated in vivo model of diabetes;intraperitoneal injection of STZ to establish diabetic mice model;The activation of MMP-9 was measured by gelatin zymography;NF-kappa B transcription was measured by immunofluorescence method;Blood glucose levels were determined by glucose meter;The morphology of mouse retina was observed by HE staining.Results:High glucose increased the activation of MMP-9 in BV2 cells,which was abolished by HMGB1,TLR4,p38 MAPK and NF-?B inhibitors.Phosphorylation of p38 MAPK induced by high glucose was decreased by TLR4 inhibition in BV2 cells.Paeoniflorin induced HSP70 and SOCS3 expression,and reduced MMP-9 activation in BV2 cells.The effect of paeoniflorin on SOCS3 was abolished by TLR4 inhibitor.In STZ-induced diabetes mice,paeoniflorin induced SOCS3 expression and reduced MMP-9 activation.Paeoniflorin suppressed STZ-induced IBA1 and IL-1? expression,and decreased STZ-induced high blood glucose level.Paeoniflorin improves the morphological structure of the retina in STZ-induced diabetic mice.Conclusions:High glucose increased microglial MMP-9 activation via the HMGB1-TLR4-NF-?B axis to break BRB and induced DR.Paeoniflorin induced microglial SOCS3 expression through HSP70/TLR4/NF-?B signaling pathway to reduced MMP-9 activation,and attenuated DR.