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Proliferative vitreoretinopathy (PVR) is a complication of ocular trauma, rhegmatogenous retinal detachment (RRD), and also a common cause of RRD repair surgery failure.Abnormal proliferation, migration and epithelial mesenchymal transition (EMT) of retinal pigment epithelium (RPE) cells play a leading role in the formation of PVR epiretinal membrane.Rapamycin is the specific inhibitor of mammalian target of rapamycin (mTOR). It selectively binds to the cell protein FKBP-12 and directly binds to the FKBP12-rapamycin domain (FRB) of FKBP rapamycin associated protein (FRAP) to inhibit mTOR activity.Rapamycin has a variety of rapalog (rapamycin analog), which inhibits cell proliferation and regulate cell cycle by inhibiting mTOR signal transduction pathway.It also plays a certain role in inhibiting RPE cell abnormal proliferation, migration and EMT in PVR, and protecting the repair of glial cells, inhibiting the inflammatory cells and preventing the vascular endothelial cell damage.In recent years, the clinical trials and drug studies have shown the important role of rapamycin in ocular diseases.In addition, the evidence on ocular administrations and drug safety of rapamycin has been gradually accumulated.This article reviewed the protective effects and safety of rapamycin on RPE cells and other cells in PVR.
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Objective:To observe the level of microparticles in the vitreous of patients with proliferative diabetic retinopathy (PDR), and preliminarily explore the role of microparticles in the pathogenesis of PDR.Methods:A case control study. From January to December 2018, 54 cases of 54 eyes of PDR patients (PDR group) and 20 cases of non-diabetic retinopathy patients (control group), who were diagnosed and treated with vitrectomy (PPV) in the Department of Ophthalmology, Tianjin Medical University General Hospital vitreous samples were included in the study. Among 54 eyes in the PDR group, there were 42, 21, and 17 eyes with vitreous hemorrhage (VH), traction retinal detachment (TRD), and previous intravitreal injection of drugs, respectively. Among the 20 eyes of the control group, idiopathic macular hole, idiopathic anterior macular membrane, vitreous macular traction syndrome, and complete lens dislocation were 6, 6, 2, and 6 eyes, respectively. The PDR group was divided into uncombined TRD group and combined TRD group according to PDR stage and whether TRD occurred, with 33 and 21 eyes, respectively. According to the presence or absence of VH, they were divided into groups with VH and without VH, with 42 eyes and 12 eyes, respectively. According to whether anti-vascular endothelial growth factor (VEGF) drugs were injected into the intravitreal cavity 3 days before PPV, they were divided into anti-VEGF drug group and no anti-VEGF drug group, with 17 eyes and 37 eyes respectively. The levels of retinal photoreceptor cells (RMP), platelets (PMP), endothelial cells (EMP) and phosphatidylserine (PS-MP) expressing on the membrane surface in the sample were detected by flow cytometry. The comparison between the two groups of samples was performed by t test, and the comparison between multiple groups of samples was performed by one-way analysis of variance or Mann-Whitney test. Results:Compared with the control group, the vitreous RMP level of the PDR group was significantly decreased, and the EMP and PMP levels were significantly increased. The differences were statistically significant ( t=-2.361, 5.064, 3.531; P=0.018, <0.001, 0.001). There was no statistically significant difference in PS-MP levels between the two groups ( t=-1.617, P=0.110). Compared with the TRD group, the levels of RMP and PMP in the vitreous of the TRD group were significantly increased, and the difference was statistically significant ( t=-2.221, -2.098; P=0.031, 0.041). The level of EMP in the vitreous body of the anti-VEGF drug group was significantly lower than that of the non-anti-VEGF drug group, however, it was still higher than the control group. The difference was statistically significant ( Z=-2.430, -2.499; P=0.015, 0.012). The level of PMP in the vitreous body of the eye without VH was significantly higher than that in the group with VH, and the difference was statistically significant ( t=-3.097, P=0.003). Conclusions:The elevated levels of EMP and PMP in the vitreous of PDR patients may be related to the damage of retinal capillaries; intravitreal injection of anti-VEGF drugs before surgery can reduce the level of EMP. VH may be related to the procoagulant effect of PMP.
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Background Clinical work found that triamcinolone acetonide (TA)bleeding during vitrectomy in proliferative diabetic retinopathy (PDR),but its mechanism is not clear.Objective This study was to explore the anastalsis of TA in vitrectomy for PDR.Methods A prospective study was performed.Twelve eyes of 12 patients who received vitrectomy combined with the intraocular use of TA for PDR were in cluded in Tianjin Medical University General Hospital from 2011 to 2014 and served as TA group.Thirty-two eyes of 32 patients who underwent vitrectomy for epimacular membrane or macular hole were enrolled as control group.The vitreous specimens of 0.6 ～0.8 ml was collected during the surgery.The concentrations of urokinase plasminogen activator (u-PA),tissue plasminogen activator (t-PA) and plasminogen activator inhibitors 1 (PAI-1) in vatreous were measured by ELISA.Results The mean contents u-PA,t-PA and PAI-1 in the vatreous were 25.45,127.44 and 0.42 ng/ml respectively in the TA group,and those the mean contents in the control group were 22.94,142.37 and 0.27 ng/ml respectively,shouwing a significant difference between the TA group and the control group (Z=-2.268,P＜0.05).NO significant difference was found in vitreous t-PA and PAI-1 between TA and control groups (Z =-0.092,-1.847,both at P＞0.05).Conclusions Vitreous u-PA content is increased in PDR eyes,which is more likely to lead bleeding.Anastalsis of TA during vitrectomy for PDR may be relatived to decreasing vitreous t-PA and u-PA contents as well as increasing PAI-1 contents.