The mineralocorticoid receptor (MR) belongs to the nuclear receptor superfamily and is expressed in the retina and choroid. MR antagonist (MRA) has a long history of application in non-ophthalmic clinical practice. Various cellular and animal models indicated that inappropriate activation of MR participated in pathological angiogenesis, oxidative stress, inflammation, disturbance of ion/water homeostasis and neurodegenerative changes, while the application of MRA can reduce or reverse these pathological processes. After using MRA in central serous chorioretinopathy (CSC) patients, improved visual function, less subretinal fluid and reduced sub-foveal choroidal thickness were observed. Single nucleotide polymorphisms in MR and plasma aldosterone levels were significantly different between chronic CSC patients and CSC patients with spontaneous remission. Novel formulation for sustained-release MRA and the mechanisms involving inflammation may become the new focus of MR study. This review summarizes the research status of MR and MRA in order to provide a reference for future basic research and clinical treatment.
Objective To investigate the polymorphism of the vitamin D receptor gene (VDR)TaqⅠin relation to diabetic retinopathy. Method Fragment length discrepant allele specific PCR(FLDAS-PCR) were used to determine VDR genetypes in 158 patients with diabetic retinopathy and in 198 normal subjects. Results The frequency distribution of VDR genotypes in diabetic retinopathy patients was 106 (67.1%) in TT, 33(20.9%) in Tt, 19(12.0%) in tt; and in normal persons was 165 (83.3%) in TT, 23(11.6%) in Tt, 10 (5.1%) in tt. There was a significant difference between diabetic retinopathy patients and normal persons in distribution of VDR gene TaqⅠgenotypes(Plt;0.05). Conclusions There is some distribution alterations of VDR gene polymorphism in diabetic retinopathy patients. (Chin J Ocul Fundus Dis, 2006, 22: 94-96)
Objective To observe the expression of erythropoietin (EPO) and EPO receptor (EPOR) in detached retina in rat model. Methods Fourty-eight male SD rats were randomly divided into control group and retinal detachment (RD) groups (1 hour, 3, 6, 12, 24, 48, and 72 hours group) with 6 rats (12 eyes) in each group. 1.4% hyaluronic acid was slowly injected into the subretinal space to induce the detachment of the upper retina to set up the RD model. The expression levels of mRNA and protein of EPO and EPOR were measured by RT-PCR and western-blotting analysis. Meanwhile, the locations of EPO and EPOR in retina were checked by immunohistochemistry. Results Both of the mRNA and protein levels of EPO and EPOR increased after RD, and reached the peak at the 48th hour after RD. The mRNA levels of EPO and EPOR were significantly higher in the 6 and 12 hours group than that in the control group（Plt;0.05）. The protein levels of EPO and EPOR were significantly higher in 3 hours group than that in the control group（Plt;0.05）. Immunohistochemistry indicated weak expression of EPO from ganglion cell layer to inner and outer segment of photoreceptor cells, and b expression in the corresponding location was found 48 hours after RD. Expression of EPOR from ganglion cell layer to inner segment of photoreceptor cells in the normal retina was detected, and b expression in the corresponding location was found 48 hours after RD. Conclusion The expression of EPO and EPOR in retina increases gradually after RD, and reaches the peak at the 48th hour; most of the layers of neural retina can express EPO and EPOR.
Objective To investigate the effect of hypoxia on the exp ression and function of integrin receptor αvβ3 of bovine retinal vascular endotheliocytes. Methods Bovine retinal vascular endotheliocy tes in the culture dishes coated by vitronectin was put into the normal and hypoxemic condition, respectively. Enzyme linked immunosorbent assay and cell adhesion analysis were used to detect the expression and function of integrin receptor αvβ3 in bovine retinal vascular endotheliocytes, respectively. Results Under the condition of hypoxia, the expression of αvβ3 increased gradually, and reached the peak at the 48th hour. The expression of αvβ3 at the 60th and 72nd hour in hypoxia group was higher than that in the normal group. Bovine retinal vascular endotheliocytes absorbed more Vn of extra-cellular matrixes (ECM) after cultured under hypoxemic condition for 24 hours.Conclusion Hypoxia may up-regulate the expression of αvβ3, which promote the adsorbability of endotheliocytes.(Chin J Ocul Fundus Dis，2004，20：360-363)
Objective To investigate the expression of T cell receptor (TCR) Vβ8.3 gene on CD4+ T lymphocytes in the rats with experimental autoimmune uveoretinitis (EAU). Methods Eighteen Lewis rats were divided into EAU, complete Freund′s adjuvant, and the control group. Inter photoreceptor retinoid-binding protein (IRBP) R16 peptide was synthesized using Fmoc procedure for induction of EAU. Magnetic absorption cell sorting (MACS) me thod was used to isolate the CD4+T lymphocytes from the spleen of the rats. Flow cytometry was used to monitor the efficiency of isolation. The expression of TCR Vβ8.3 gene segment on CD4+T lymphocytes was determined by fluorescent quantitative polymerase chain reaction. Results EAU was successfully induced in the Lewis rats immunized with IRBP R16 peptide. The proportion of CD4+T lymphocytes isolated by means of MACS was statistically higher than that before isolation (P＜0.001). The expression of TCR Vβ8.3 gene segment on CD4+ T lymphocytes in EAU rats was significantly higher than that in the control (P＜0.05). Conclusions There is a predominant usage of antigen-specific TCR Vβ 8.3 gene in EAU rats induced by IR BP R16 peptide, which may serve as a target for immunotherapy of EAU. (Chin J Ocul Fundus Dis，2004，20：165-167)
Objective To investigate the alteration of protein kinase C (PKC) and endothelin system in early diabetic rats, and the effect of specific PKC inhibitor on the expression of retinal endothelin-1 (ET-1). Methods The rats model with streptozotocin(STZ)-induced diabetes were set up. The expression of retinal PKC was detected by enzyme-linked immunoabsorbent assay (ELISA). The expression of retinal ET-1, ET-3, ET-A and ET-B receptor mRNA was determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The alteration of retinal ET-1 mRNA after intravitreal injection of PKC inhibitor GF109203X in diabetic rats was also observed. Results The activities of membranous PKC were significantly increased in 2-week diabetic rats compared with that in normal rats（t=3.296 , P=0.008）, while activities of cytosolic PKC were unchangeable（t=0.138, P=0.894）. The expression of retinal ET-1 mRNA was significantly increased（P=0.008）, while no change was found in expression of ET-3, ET-A and ET-B mRNA（P=0.918，P=0.889，P=0.500）. After intravitreal in jection of 10-5、10-6、10-7 mol/L PKC inhibitor GF109203X in diabetic rats, the expression of retinal ET-1 mRNA was decreased in a dose-dependent manner compared with the control rats. Conclusion Activation of PKC and increased expression of ET-1 could be found in the retina of early diabetic rats, and PKC inhibitor could inhibit the expression of retinal ET-1. (Chin J Ocul Fundus Dis，2004，20：168-171)
Objective To investigate the response of retinal ganglion cells （RGC）in detached and reattached retina in adult rats, and the effect of IL-1beta antibody and IL-1Ra on the loss of RGC. Methods A total of 73 Sprague-Dawley (SD) rats were subretinally injected with healon GV（1.4% hyaluronate）and retrograde labeled with fluorogold (FG), and 10 ng IL-1 Ra and 500 ng IL-1beta antibody were injected into the subretinal space combined with healon GV. The retinal flakes were observed under the fluoroscope and the number of RGC was counted 2 hours, 1, 3, 5, 7, 10, 20, 50, and 90 days after deta chment; 10 days after detachment and 30 days after reattachement; 90 days after detachment and 20 days after reattachement, and 1 and 10 days after injection with IL-1beta antibody and IL-1Ra,respectively. And the control group was only developed an intraocular injection of the same valume of healon GV. Result Two hours after detachment, the RGC loss was found, reached the peak at first day, and decreased gradually. RGC loss was also found in the non-detached area. The reattachment 10 days after detachment (early reattachment) stopped the loss of RGC, and the reattachment 90 days after detachment (late reattachment) promoted the loss, which rested on a certain level. Subretinal space injection of IL-1Ra and IL-1beta antibody decreased the loss of RGCs in the detached retina. Conclusion The RGCs loss were found both in the detached and attached retina. Early reattachment may stop the loss of RGC, and late reattachment may promote the loss. Both IL-1beta antibody and IL-1Ra have neuro protective effect on RGC. (Chin J Ocul Fundus Dis，2004，20：233-236)
ObjectiveTo observe the effect of complement receptor 1 (CR1) on barrier of cultured human retinal epithelial cells (hRPE) under complement-activated oxidative stress. MethodsThe third to fifth passage of hRPE cultured on Transwell insert were used to establish a stable hRPE monolayer barrier. The hRPE monolayer barrier was exposed to 500 μmol/L ten-butyl hydroperoxide and 10% normal human serum to establish the hRPE monolayer barrier model of complement-activated oxidative stress in vitro. hRPE monolayer barriers under complement-activated oxidative stress were divided into two groups including model group and CR1 treatment (1 μg/ml) group. Model group and CR1 treatment group were treated with 1 μl phosphate buffer solution (PBS) or CR1 for 4 hours. Normal hRPE monolayer barrier were used as control in transepithelial resistance (TER) measurement experiment. TER was measured to evaluate the barrier function of hRPE. The hRPE-secreted vascular endothelial growth factor (VEGF) and chemokine (C-C Motif) Ligand 2 (CCL2), together with complement bioactive fragments (C3a, C5a) and membrane-attack complex (MAC) in the supernatant were detected by enzyme-linked immune sorbent assay. ResultsStable hRPE monolayer barrier was established 3 weeks after hRPE seeded on Transwell insert. Complement-activated oxidative stress resulted in a sharp decrease of TER to 54.51% compared with normal hRPE barrier. CR1 treatment could significantly improve TER of barrier under complement-activated oxidative stress to 63.48% compared with normal hRPE barrier(t=21.60, P < 0.05). Compared with model group, CR1 treatment could significantly decrease the concentration of VEGF and CCL2 by 11.48% and 23.47% secreted by hRPE under complement-activated oxidative stress (t=3.26, 2.43; P < 0.05). Compared with model group, CR1 treatment could also decreased the concentration of C3a, C5a and MAC by 24.00%, 27.87%, 22.44%.The difference were statistically significant (t=9.86, 2.63, 6.94; P < 0.05). ConclusionsCR1 could protect the barrier function of hRPE cells against complement-activated oxidative stress. The underlying mechanism may involve inhibiting complement activation and down-regulating the expression of VEGF and CCL2.
Neovascularization is a characteristic manifestation of a variety of retinal diseases. Vascular endothelial growth factor (VEGF) mainly regulates the proliferation and migration of endothelial cells. VEGF receptor 2 (VEGFR2) is the main receptor to mediate this effect. The activation of downstream signals requires the binding of VEGF and VEGFR2, followed by receptor dimerization and autophosphorylation. Blocking this process and inhibiting neovascularization is very attractive treatment ideas. Monoclonal antibodies and fusion protein drugs currently used in ophthalmology can bind free VEGF. In addition, there are also macromolecular antibodies binding VEGFR2 and small molecule tyrosine kinase inhibitors, which is expected to further expand into the field of ophthalmology. Although anti-VEGFR2 therapy is a revolutionary method to inhibit neovascularization, there are no sufficient clinical evidences at present. In-depth understanding of the application status and progress of anti-VEGFR2 in the treatment of retinal neovascular diseases has important clinical significance.
ObjectiveTo investigate the effects and mechanisms of G protein-coupled receptor 91 (GPR91) on blood-retinal barrier (BRB) in diabetic rats. MethodsA lentiviral vector of shRNA targeting rat GPR91 and scrambled shRNA were constructed. Healthy male Sprague-Dawley (SD) rats were selected in this study. The 60 rats were randomized into 4 groups and treated as follows:(1) control group (Group A, n=15), the rats received injections of an equal volume of 0.1% citrate buffer; (2) streptozocin (STZ) group (Group B, n=15), the rats received injections of STZ; (3) LV.shScrambled group (Group C, n=15), diabetic rats received an intravitreal injection of 1 μl 1×108 TU/ml scrambled shRNA lentiviral particles at 2 weeks after the induction of diabetes; (4) LV.shGPR91 group (Group D, n=15), diabetic rats received an intravitreal injection of 1 μl 1×108 TU/ml pGCSIL-GFP-shGPR91 lentiviral particles. At 12 weeks after intravitreal injection, immunohistochemistry and Western blot were used to assess the expression of GPR91, p-extracellular signal-regulated kinase(ERK)1/2, t-ERK1/2, p-Jun N-terminal kinase (JNK), t-JNK, p-p38 mitogen-activated protein kinase (MAPK) and t-p38 MAPK. Haematoxylin and eosin (HE) staining and Evans blue dye were used to assess the structure and function of the retinal vessel. Immunohistochemistry enzyme-linked immunosorbent assay (ELISA) was used to test the protein level of VEGF. ResultsImmunohistochemistry staining showed that GPR91 was predominantly localized to the cell bodies of the ganglion cell layer. Western blot showed that GPR91 expression in Group D decreased significantly compared with Group C (F=39.31, P < 0.01). HE staining showed that the retina tissue in Group B and C developed telangiectatic vessels in the inner layer of retina, while the telangiectatic vessels attenuated in Group D. It was also demonstrated in Evans blue dye that the microvascular leakage in Group D decreased by (33.8±4.11)% compared with Group C and there was significant difference (F=30.35, P < 0.05). The results of ELISA showed the VEGF secretion of Group B and C increased compared with Group A and the VEGF expression in Group D was significantly down regulated after silencing GPR91 gene (F=253.15, P < 0.05).The results of Western blot indicated that compared with Group A, the expressions of p-ERK1/2, p-JNK and p-p38 MAPK were significantly upregulated (q=6.38, 2.94, 3.45;P < 0.05). Meanwhile, the activation of ERK1/2 was inhibited by GPR91 shRNA and the difference was statistically significant (F=22.50, P < 0.05). ConclusionsThe intravitreal injection of GPR91 shRNA attenuated the leakage of BRB in diabetic rats. GPR91 regulated the VEGF release and the leakage of BRB possibly through the ERK1/2 signaling pathway.