PGF2α Protecting Against Non-proliferative Diabetic Retinopathy In Type 2 Diabetic Patients

Non-proliferative diabetic retinopathy（NPDR）is the most important early microvascular complication in patients with type 2 diabetes（T2D）,which manifestes as retinal microvascular leakage,vascular wall thinning,and functional retinal microvascular reduction.Blood glucose,blood pressure,and diabetic duration are major risk factors for NPDR.Patients with more than 10 years of T2D still suffer from diabetic retinopathy（DR）even under proper blood glucose control.The specific mechanism is not clear.It has been reported that polyunsaturated fatty acids（PUFAs）supplementation in diets could reduce the risk of NPDR in well-controlled T2D patients and the severity of retinopathy in patients with NPDR.The prevention of NPDR can effectively reduce the incidence of diabetic retinal vascular injury in T2D patients,which has important clinical significance.We have established a targeted and high-throughput metabolomic method for PUFA metabolites,with good sensitivity and specificity.The purpose of this study was to elucidate the PUFAs metabolic profile in the plasma of T2D patients with or without NPDR and reveal the relevant mechanism.To study the relationship between eicosanoids and NPDR,a total of 50 type 2diabetic patients were recruited and divided into non-DR（NDR）group and NPDR group based on fundus photographs.There was no statistical difference in age,sex,and duration of diabetes between groups.Plasma and clinical data of the patients were collected for further analysis.The eicosanoids profiles in plasma were determined by LC-MS/MS.PGF2α,the eicosanoid derivative of the arachidonic acid,was decreased significantly in NPDR group compared to NDR group.Furthermore,PGF2αwas found to be correlated with NPDR.The correlation was robust when adjusted for clinical risk factors of NPDR.At the cellular level,the mobility of retinal pericytes plays a key role in NPDR.Sustained high glucose reduces the mobility of retinal pericytes,thereby increasing vascular permeability and degeneration,leading to early symptoms of NPDR.We isolated primary bovine retinal pericytes（BRPC）and treated with PGF2α（100 nM）under high glucose（25 mM D-glucose）conditions.The results showed that PGF2αpromoted BRPC migration,adhesion and the polarization of cytoskeleton protein by transwell,adhesion,and immunofluorescence staining assay,respectively.FP receptor is a currently known specific receptor for PGF2α.We found that FP receptor-specific inhibitor（AL8810）diminished the effect of PGF2αin the migration,adhesion and cytoskeletal changes of BRPC.FP receptor is a G-protein coupled receptor and may promote the activation of Rho,thereby promoting the rearrangement of cytoskeletal proteins.By Active-Rho pull-down experiments,we further confirmed that PGF2αincreased Active-RhoA level.Taken together,in vitro experiments showed that PGF2αpromoted BRPC mobility through activation of RhoA in an FP receptor-dependent manner.To further show the critical roles of PGF2αon NPDR,8-week-old C57BL/6mouse were used to establish STZ-induced diabetic mouse model by STZ injection for 1 week.After another one week for recovery,the mice were treated with Latanoprost（agonist of FP receptor,40mg/Kg）for 2 or 6 weeks.Retinas were harvested at the end of the 4^thh or 8^th week.At the 8^th week after STZ injection,retinal vascular area was significantly reduced in the central and peripheral.Meanwhile,Latanoprost attenuated diabetic microvascular damage in those mice,especially at 8^thh week.Taken together,our results suggested that PGF2αwas determined as a protective metabolite according to PUFA metabolomics analysis of plasma of T2D patients.Cell experiments showed that PGF2αenhances migration,adhesion and cytoskeleton polarization of retinal pericytes by increasing the RhoA activity in FP receptor-dependent manner.Further in vivo experiments demonstrated that FP receptor agonist protects STZ-induced diabetic mouse from the damage of retinal capillaries.PGF2αis of great significance for the early prevention and treatment of NPDR in T2D patients.