The pathogenesis of diabetic retinopathy is complicated. The vast network of multiple factors including unifying mechanism, inflammatory reaction, neuron degeneration and metabolic memory of glucose, and the four established pathogenic molecular pathways are hotspots of mechanism research for diabetic retinopathy. Nevertheless, these researches may be only one corner of the ldquo;icebergrdquo; of DR mechanism, and we still face enormous challenges in DR mechanism research. Collaboration with multiple disciplines to study the relationship between DR and diabetes and other systemic diseases, search novel therapy targets may increase the result in an unexpected windfall for DR basic research.
Objective To observe the oxidative damage of mtDNA, apoptosis and expression of adhesion molecules in retinal capillary cells of diabetic rat with different disease courses. Methods One hundred Sprague-Dawley rats were randomly divided into the control group and the experimental group. The rats of experimental group were induced with streptozotocin (STZ) injection creating a diabetic model. Then they were divided into DR1m, DR2m DR3m group according to disease courses. The rats of control group were divided into NR1m, NR2m, NR3m group. Rat retinal capillaries were prepared, and then the contents of undamaged mtDNA were examined by Southern blot combined with Fpg. The expression of cyclooxygenase (COX)-1 encoded by mtDNA and transcription factors A (mtTFA) mRNA were detected by real-time quantitative polymerase chain reaction (RT-PCR). Apoptosis and expression of intercellular adhesion molecule-1 (ICAM-1) were detected by terminal dUT nick endlabeling (TUNEL) immuno-fluorescence and immunohistochemistry respectively. Results The contents of undamaged mtDNA in rats of DR1m, DR2m, DR3m were less than those of NR1m、NR2m、NR3m. The contents of undamaged mtDNA in diabetic rats decreased with the increase of disease courses. In addition, the mRNA levels of COX-1 and mtTFA were downregulated in diabetic rats. The positive cells of TUNEL and ICAM-1TUNEL and ICAM-1 in diabetic rats increased with the increase of disease courses. Conclusion With the increase of disease courses, mtDNA damage and apoptotic cells are increased, while the expression of mRNA encoded by mtDNA and ICAM-1 decreased in retinal capillary cells in diabetic rats.
Objective To explore and evaluate the protective effects of soluble fms-like tyrosine kinase recptor-1(sFlt-1) gene 2-3 and 2-4 transcellular region on retinal vascular leakage and phosphatidyl inositol-3 kinase (PI3K)/Akt pathway under hypoxia and/or hyperglycemia. Methods The plasmids pcDNA3.1-EGFP/sFlt-1(2-3) and pcDNA3.1-EGFP/sFlt-1(2-4) were constructed.. Two of these plasmids with carboxy methylation glucan (CMD) magnetic particles were transfected into human umbilical vein endothelial cells (HUVEC), which were cultured under hypoxia and/or hyperglycemia. The blood retinal barrier was evaluated by Evans blue permeation (EBP). Then the expression of p-Akt mRNA and protein were detected by reverse transcriptionpolymerase chain reaction (RT-PCR) and Western blot separately. Results In the diabetic rabbits, The blood retinal barrier breakdown was detected by the retinal vascular leakage of EBP. The expression of p-Akt mRNA and protein in hypoxia and hyperglycemia groups were also obviously increased. These changes were largely prevented by transfection the plasmids pcDNA3.1-EGFP/sFlt-1(2-3) and pcDNA3.1-EGFP/sFlt-1(2-4) (P＜0.01 in both groups). Conclusion Both sFlt-1(2-3) and sFlt-1(2-4) can make the retinal blood vessels less leaky and may be beneficial in preventing vision loss from diabetic retinopathy.
Objective To expolre the factors which affect the size of diabetic,macular fobeal avascss scular zone(FAZ). Methods Making ten years of duration of diabetes a limit,79 nonproliferative and early proliferative diabetic patients were divided into 2 groups.Diabetic retinopathy severity level was diveided into 4 stages,and the macular edema was subdivided into focal、diffuse and cystoid according to fluorescein leakage of foveomacular region.All patients were measured FAZ with Heidelberg scanning laser fluoresceion angiography system and then compaired the size of FAZ of patients with different duration of diabetes、diabetic retinopathy severity level and macular edema status.The results were performed analysis of variance and t test. ResultsThe study shown the size of FAZ was not directly related to the duration of diabetes(t=1.3854,Pgt;0.1);There were significant differences about the size of FAZ of patients with different diabetic retinopathy severity level(F=7.6251,P＜0.01)and macular edema status(F=5.4369,P＜0.01)． Conclusion The size of FAZ was significantly increased in diabetic patients.It was enlarged with the development of diabetic retinopathy severity level,but it was not related to duration of diabetes. (Chin J Ocul Fundus Dis,2000,16:155-156)
ObjectiveTo observe the effect of phase Ⅱenzyme inducer 5, 6-dihydrocyclopenta 1, 2-dithiole-3-thione (CPDT) on nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) signal pathway and oxidative stress in the retina of type 2 diabetic rats. MethodsThirty-five male Wistar rats were randomly divided into two group, normal group and model group. Model group were further randomly divided into two group, diabetic group and CPDT intervention group. There were 8 rats in the normal group and 27 rats in the model group. Diabetic group and CPDT intervention group were given high fat and high sugar diet for 2 months. After 12 hours of fasting, type 2 diabetic rat model was induced by intraperitoneal injection of low dose of streptozotocin. CPDT was added into the high fat and high sugar diets at 1 week after the diabetic model was established in the CPDT intervention group. Eight weeks after CPDT treatment, blood glucose, serum malondialdehyde (MDA), blood lipid, Nrf2 and hemeoxygenase-1 (HO-1) expression were evaluated. ResultsType 2 diabetic model was successfully established in 25 rats, the success rate was 92.6%.The level of blood lipid of diabetic group was higher than those of the normal group (FTC=65.866, FTG=25.441, FLDL-C=38.889; P=0.000). Blood glucose was significant different between all groups (χ2=25.812, P=0.000), and was significantly higher in diabetic group than that in normal group and CPDT intervention group. The serum MDA content was significant different between all groups (F=59.545, P=0.000), and was significantly higher in diabetic group than that in normal group (t=10.523, P=0.000) and CPDT intervention group (t=7.766, P=0.000). The mRNA level of retinal Nrf2 and HO-1 was significant different between all groups (FNrf2=19.503, PNrf2=0.000;FHO-1=9.737, PHO-1=0.001), and was higher in CPDT intervention group than the diabetic group (tNrf2=3.399, PNrf2=0.002;tHO-1=2.167, PHO-1=0.039). The protein level of retinal Nrf2 and HO-1 was significant different between all groups (FNrf2=112.823, FHO-1=119.361; P=0.000), and was higher in CPDT intervention group than the diabetic group (tNrf2=6.203, tHO-1=6.388; P=0.000). Immuno-staining showed that Nrf2 and HO-1 were mainly expressed in retinal ganglion cell layer, inner plexiform layer and inner nuclear layer, and were significant different between all groups (FNrf2=16.206, FHO-1=46.790; P=0.000). They also were higher in CPDT intervention group than the diabetic group (tNrf2=3.172, PNrf2=0.003;tHO-1=6.321, PHO-1=0.000), was higher in diabetic group than that in normal group (tNrf2=2.679, PNrf2=0.011;tHO-1=3.482, PHO-1=0.001). ConclusionCPDT may activate Nrf2/ARE pathway, induce Nrf2 and HO-1 expression, decrease serum MDA and blood glucose, and thus reduce oxidative stress injury in the retina of type 2 diabetic rats.
ObjectiveTo observe the expression of vascular endothelial growth inhibitor (VEGI, TL1A), vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in diabetes rats' serum, vitreous and retina, and discuss the role of VEGI in the pathogenesis of diabetic retinopathy (DR). MethodsA total of p70 adult male Wistar rats were randomly divided into 4 groups, the control group (10 rats), the diabetes mellitus (DM) 1 month group (20 rats), the DM 3 month group (20 rats) and the DM 6 month group (20 rats). Cytokines of serum and vitreous were determined by enzyme-linked immunosorbent assay (ELISA), and the concentrations of the cytokines in the retina were determined by immunohistochemistry on paraffin retinal sections. Hematoxylin-eosin (HE) staining of retina was used to estimate the pathological change of DR. The results were analyzed by one-way analysis of variances, independent samples t-test and LSD test. ResultsThe serum TL1A levels of the control group, the DM 1 month group, the DM 3 month group and the DM 6 month group rats were (92.09±2.05), (118.36±8.30), (85.90±7.51) and (78.90±4.88) ng/L respectively, the level of TL1A in serum of the DM 1 month group, the DM 3 month group and the DM 6 month group were significantly lower than that of the control group (F=77.405, P < 0.05). The concentration of serum TNF-α and IL-1β increased after DM model was established (F=3.508, 15.416; P < 0.05); the VEGF level in serum showed no difference between the groups (F=1.242, P > 0.05). The vitreous TL1A levels of the control group, the DM 1 month group, the DM 3 month group and the DM 6 month group were (91.50±8.18), (67.03±6.74), (47.44±4.92) and (46.01±4.62) ng/L respectively, every DM groups showed significant difference with the control group (F=114.777, P < 0.05); VEGF level in vitreous increased from 1 month after DM model was established (F=8.816, P < 0.05); TNF-α and IL-1β level in vitreous also showed an upward tendency (F=4.392, 3.635; P < 0.05). Paraffin section immunohistochemistry showed that the absorbance (also called optical density) of TL1A of the DM 1 month group and the DM 3 month group were significantly lower than that of the control group (t=6.851, 6.066; P < 0.05), but the DM 6 month group showed no difference with the control group (t=1.401, P > 0.05); the level of VEGF and TNF-α in DM groups were higher than that of the control group (tVEGF=-4.709, -16.406, -9.228; tTNF-α=-4.703, -6.583, -17.762; P < 0.05); the level of IL-1β were significantly higher in the DM 1 month group and the DM 6 month group (t=-4.108, -3.495; P > 0.05); but the DM 3 month showed no difference with the control group (t=-0.997, P > 0.05). HE staining of retina showed that the retina of the control group and the DM 1 month group had normal retinal structures, the DM 3 month group had retinal edema and disorganization, the DM 6 month group had severe retinal edema, deep stain of ganglion cells, and more neovascularization in inner plexiform layer. ConclusionVEGI is involved in the pathogenesis of DR, and it might interacts with VEGF, TNF-α and IL-1β to affect the development of DR.
ObjectiveTo observe the expression of Toll-like receptor 4 (TLR4) and inflammatory cytokines, leucocytic density and permeability in retina of diabetic rat. MethodsA total of 106 Brown Norway rats were randomly divided into experimental group and control group with 53 rats in each group. Diabetic model was established in experimental group by intraperitoneal injection of streptozotocin, and control rats received intraperitoneal injection of an equal volume of citric acid-sodium citrate buffer. Four weeks later, the retinas were collected for further analysis. TLR4 RNA and protein expression were measured by quantitative polymerase chain reaction and Western blot. Inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemo-attractant protein-1 (MCP-1), were measured by enzyme-linked immunosorbent assay in rat retina homogenate. Leukocyte density in the retina was measured by acridine orange fundus angiography. The retinal permeability was evaluated by Evans blue (EB) staining. ResultsTLR4 expression was significantly increased in diabetic rats of experimental group compared with non-diabetic rats of control group (F=1.606, 0.789; P < 0.05). Inflammatory cytokines (TNF-α, IL-1β and MCP-1) were significantly increased in retina of diabetic rats of experimental group versus non-diabetic rat of control group (F=24.622, 5.758, 4.829; P < 0.05). The retinal leukocyte density was (6.2±0.5)×10-5, (2.2±0.3)×10-5 cells/pixel2 in experimental and control group respectively, the difference was statistically significant (F=2.025, P < 0.05). The amount of retinal EB leakage was (23.41±4.47), (13.22±3.59) ng/mg in experimental and control group respectively, the difference was statistically significant (F=21.08, P < 0.05). ConclusionTLR4 and inflammatory cytokines expression, leucocytic density and permeability increased significantly in retina of diabetic rat.
Objective To investigate the cellular viability and mitochondrial reactive oxygen species (ROS) production of the Müller cells under high glucose condition, and explore the protection role of the 5,6-dihydrocyclopenta-1, 2-dithiole-3-thione (CPDT) on Müller cells. Methods Müller cells from Sprague Dawley rats were divided into 5 groups randomly, including 25 mmol/L normal glucose group (group A) and 65 mmol/L high glucose group (group B). High glucose group with 45, 60, 70 μmol/L CPDT and cultured them 72 hour was set as group C, D and E. Water soluble tetrazolium salt (WST)-8 was used to measure the cellular viability. Flow cytometry was used to measure the active oxygen and apoptosis index. The expression of nuclear factor erythroid 2-related factor 2 (Nrf2), hemeoxygenase-1 (HO-1), Bcl-2 and Bax protein were measured by Western blot. Results Compared with group A, the WST-8 showed that the viability of Müller cells apparently decreased in group B (t=39.59,P＜0.05). Compared with the group B, the viability of Müller cells had changes in group C (t=0.97,P＞0.05), but recovered in group D and E (t=−4.17, −7.52;P＜0.05). Compared with group A, the FCM showed that the mitochondrial ROS levels was higher in group B (t=−30.99,P＜0.05). Compared with group B, the mitochondrial ROS levels were decreased in group D (t=27.68,P＜0.05). Compared with group A, Bax, Nrf2 and HO-1 increased (t=–11.03, –63.17, –11.44;P＜0.05), while the bcl-2 decreased in group B (t=7.861,P＜0.05). Compared with the group B, Nrf2, HO-1 and Bax decreased (t=15.11, 26.59, 6.27;P＜0.05), while the bcl-2 increased in group D (t=−6.53,P＜0.05). Conclusions Under the high glucose, CPDT may reduce the mitochondrial ROS levels and the expression of Nrf2, HO-1 and Bax protein of Müller cells. It may inhibit apoptosis through activating the Nrf2/HO-1 pathway and balancing of level of Bcl-2 protein and mitochondrial ROS.