Retinal Cell Damage Research Articles

The Exposure of Phosphatidylserine Influences Procoagulant Activity in Retinal Vein Occlusion by Microparticles, Blood Cells, and Endothelium.

The pathogenesis of hypercoagulability in retinal vein occlusion (RVO) is largely unknown. Whether the exposure of phosphatidylserine (PS) and microparticle (MPs) release will affect procoagulant activity (PCA) in RVO needs to be investigated. Objectives. To evaluate PS expression, circulating MPs, and the corresponding PCA in RVO patients. Twenty-five RVO patients were compared with 25 controls. PS-positive cells were detected by flow cytometry. Cell-specific MPs were measured by lactadherin for PS and relevant CD antibody. We explored PCA with coagulation time, purified coagulation complex assays, and fibrin production assays. In RVO, MPs from platelets, erythrocytes, leukocyte, and endothelial cells were increased and the exposure of PS was elevated significantly when compared with controls. In addition, we showed that circulating MPs in RVO patients were mostly derived from platelets, representing about 60–70% of all MPs, followed by erythrocytes and leukocytes. Moreover, PS exposure, ECs, and MPs in RVO lead to shortened clotting time with upregulation of FXa and thrombin formation obviously. Importantly, ECs treated with RVO serum which bounded FVa and FXa explicitly suggested the damage of retinal vein endothelial cells. Furthermore, lactadherin can inhibit the combination between PS and coagulation factors by approximately 70% and then exert an anticoagulant effect. In summary, circulating MPs and exposed PS from different cells may contribute to the increased PCA in patients with RVO. Lactadherin can be used for PS detection and an anticoagulant agent.

Protective Effects of Lycium barbarum Extracts on UVB-Induced Damage in Human Retinal Pigment Epithelial Cells Accompanied by Attenuating ROS and DNA Damage.

The medicinal herb Lycium barbarum fruit has been widely used for improving and maintaining the health of the eyes in the Far East for many centuries. This study is aimed at investigating whether protective effects generated from the aqueous (LBA) and ethanol (LBE) extracts of the L. barbarum fruit existed against oxidative stress-induced apoptosis in human retinal pigment epithelial cells. L. barbarum extracts LBA and LBE exerted the activity of ROS scavenging and rescued UVB irradiation-induced growth inhibition in retinal pigment epithelial ARPE-19 cells. Compared to LBA, the ethanol extract LBE exerted a superior protective activity on UVB-induced growth arrest in ARPE-19 cells. Both L. barbarum extracts significantly reduced cell cycle G2-arrest population in ARPE-19 cells. Furthermore, the cytometer-based Annexin V/propidium iodide staining assay further showed that both L. barbarum extracts protected ARPE-19 cells from UVB-induced apoptosis. L. barbarum extracts also reduced the activation of γH2AX, a sensor of DNA damage in ARPE-19 cells in a dose-responsive manner. By using Ingenuity Pathway Analysis (IPA), the bioinformatics revealed that the protective effects of both LBA and LBE extracts might be involved in three signaling pathways, especially the Toll-like receptor (TLR) pathway associated with cellular proliferation. Our study suggests that both ethanol and aqueous extracts of L. barbarum exhibit antioxidant activity and rescue UVB-induced apoptosis of ARPE-19 cells. Collectively, the ethanol extract exerts a superior effect on rescuing UVB-induced growth arrest of ARPE-19 compared to the aqueous extract, which might be associated with the activation of TLR signaling. Our present work will benefit the preventive strategy of herbal medicine-based vision protection for treating eye diseases such as age-related macular degeneration in the future.

Role and mechanism of NTR p75 receptor in oxidative damage of retinal pigment epithelium cells

Role and mechanism of NTR p75 receptor in oxidative damage of retinal pigment epithelium cells

Protection of Kaempferol on Oxidative Stress-Induced Retinal Pigment Epithelial Cell Damage.

The protection of retinal pigment epithelium (RPE) injury plays an important role in the prevention of or in delaying the pathological progress of retinal degeneration diseases, like age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa. Oxidative stress has been identified as a major inducer of RPE injury, which eventually could lead to a loss of vision. Kaempferol is a natural flavonoid widely distributed in many edible plants, fruits, and traditional medicines and has been reported to have antioxidant, anti-inflammatory, anticancer, and antimicrobial activities. The present study demonstrates that the total antioxidant capacity of kaempferol is approximately two times stronger than that of lutein which is also a natural antioxidant that is widely used in the prevention or treatment of AMD. Our data indicates that kaempferol protects human RPE cells (ARPE-19) from hydrogen peroxide- (H2O2-) induced oxidative cell damage and apoptosis through the signaling pathways involving Bax/Bcl-2 and caspase-3 molecules proofed by real-time PCR and Western blot results. Kaempferol also inhibits the upregulated vascular endothelial growth factor (VEGF) mRNA expression levels induced by H2O2 in ARPE-19 cells and affects the oxidation and antioxidant imbalanced system in ARPE-19 cells treated by H2O2 through the regulations of both the activities of reactive oxygen species (ROS) and superoxide dismutase (SOD). Furthermore, our in vivo experimental results show that in sodium iodate-induced retinal degeneration rat model, kaempferol could protect sodium iodate-induced pathological changes of retina tissue and retinal cells apoptosis as well as the upregulated VEGF protein expression in RPE cells. In summary, these novel findings demonstrate that kaempferol could protect oxidative stressed-human RPE cell damage through its antioxidant activity and antiapoptosis function, suggesting that kaempferol has a potential role in the prevention and therapeutic treatment of AMD or other retinal diseases mediated by oxidative stress.

Notoginsenoside R1 attenuates high glucose-induced endothelial damage in rat retinal capillary endothelial cells by modulating the intracellular redox state.

The aim of this study was to examine whether Notoginsenoside R1 (NR1) attenuates high glucose-induced cell damage in rat retinal capillary endothelial cells (RCECs) and to explore the mechanisms involved. The exposure of rat RCECs to high concentration of glucose (30 mM) for 72 h led to significant cytotoxicity, including decreased cell viability, reduced mitochondrial DNA copy number, increased lactate dehydrogenase release and elevated apoptosis. NR1, when present in the culture medium, markedly attenuated the high glucose-induced cytotoxicity in rat RCECs. Moreover, high glucose also induced a significant increase in intracellular reactive oxygen species and subsequently increased the activity of NADPH oxidase and poly-ADP (ribose) polymerase, whereas the activity of catalase decreased. The addition of NR1 to the medium significantly reduced the generation of reactive oxygen species, inhibited NADPH oxidase and poly-ADP (ribose) polymerase activities and increased catalase activity in RCECs, accompanied by a reduced cellular nitrotyrosine level. To explore the underlying mechanisms involved, the cellular redox status was monitored. Both the cellular NAD+ and NADPH levels decreased significantly in high glucose medium, which resulted in a marked decrease in the NAD+/NADH and NADPH/NADP+ ratios. High glucose stimulation also enhanced the accumulation of GSSG, maintaining the GSH/GSSG ratio lower than that in the control group with 5.5 mM glucose. When treated with NR1, the cellular NAD+, NADPH and GSH concentrations increased, and the ratios of NAD+/NADH, NADPH/NADP+ and GSH/GSSG increased, similar to the control group. These results demonstrate that NR1 attenuates high glucose-induced cell damage in RCECs. Therefore, NR1 may exert its protective effects via mechanisms that involve changes in the cellular redox state.

FluoroGold‐labeled organotypic retinal explant culture (FLOREC) for neurodegeneration and neurotoxicity screening studies

PurposeTo create a fast and reproducible system for retinal drugs toxicity screening.MethodsIn this study, we used retinal explants culture from 4 weeks old Wistar rats (n = 16). First, to determine the effect of FluoroGold (FG) on explants quality, we used 8 animals. FG was injected into midbrain of rats (n = 4) 5 days before euthanasia. Each retina after isolation was divided into 2 parts. In this way, we prepared 16 retinal explants with FG labeling and 16 explants without FG. Explants were cultured in supplemented Neurobasal A medium in Millicell culture inserts. After 7 days of culture, the explants were fixed, stained with ß3‐tubulin and processed for stereology. The culture medium was used to evaluate LDH release. The other group of 8 rats was processed in a similar way, but the culture medium was additionally supplemented with CNTF or toxic concentration of Gentamycin.ResultsWe did not observe differences between FG and no‐FG explants for ß3‐tubulin‐positive cell count and LDH release after 7 days of culture. The number of ß3‐tubulin‐positive cells was similar to FG‐labelled cells (57 ± 23; 58 ± 17 cells respectively, p > 0.5). Gentamycin treatment resulted in retinal cell damage expressed in rapid LDH release to culture medium. After 7 days of culture, the levels of LDH in medium increased up to 157 ± 57% and 144 ± 27% when compared to the corresponding LDH levels before Gentamycin exposure in no‐FG (p < 0.05) and FG (p < 0.05) explants respectively. CNTF supplementation minimized the cell damage and the release of LDH was 106 ± 36% and 104 ± 23% when compared to the corresponding LDH levels before Gentamycin exposure in no‐FG (p > 0.5) and FG (p > 0.05) explants respectively.ConclusionsThe FLOREC protocol could be considered as a fast, reproducible and sensitive method to detect neurotoxicity and neuroprotection in the screening studies of the retinal drugs.

Protective effects of tissue factor targeting peptide on human retinal pigment epithelial cell damage induced by blue light

Background Light-induced retinal damage results in the damage of retinl pigment epithelial (RPE) cells and therefore affects the pathogenesis and development of age-related macular degeneration (AMD). Studies showed that tissue factor (TF) is overexpressed in oxidative damaged RPE cells and the choroidal neovascularization (CNV) of AMD, speculating that the suppression of TF can prevent the damage of RPE cells and inhibit CNV. Objective This study was conducted to observe the protective effects of TF targeting peptide (TF-TP), a new drug of autologous synthesis, on human RPE-cells induced by blue light. Methods Human RPE cells were isolated from donor eye and cultured.Cultured cells were divided into blank control group, model group and TF-TP treated group.Light-induced RPE cell damage model was established by exposuring the cells in the blue light of (4.0±0.5)mW/cm2 for 12 hours in the model group, and different concentrations (10, 100, 150, 200, 300 μmol/L) of TF-TP were added into the medium to pretreat the cells for 24 hours and then exposed the cells to the blue light for 12 hours in the TF-TP groups.The cell viability was determined by CCK-8 assay.The morphology and ultrastructure in the cells were observed under the inverted microscope and transmission electron microscope.The apoptosis of the cells was assayed by Hoechst staining.The expressions of TF and apoptosis-related protein bax, bcl-2 in the cells were determined by Western blot. Results CCK-8 assay showed that there was no significant difference in the cell viability among blank control group and different concentrations TF-TP groups (F=2.15, P=0.11). The cell survival rate of blank control group, model group and 150 μmol/L TF-TP group was (100.0±0.00)%, (43.79±6.55)% and (63.45±3.57)%, and the survial rate was increased in the 150 μmol/L TF-TP group compared with the model group (P=0.00), and 150 μmol/L was detemined as a optimal concentration of TF-TP.A lot of shrinkage, deformation, suspension cells were exhibited under the optical microscope, and decrease of microvilli structure, rupture of mitochondrial cristae and vacuolar degeneration of the cells were found in the model group, and the damage of the cells were evidently lightened in the 150 μmol/L TF-TP group.The apoptosis rate of the cells were (0.98±0.19)%, (9.98±0.82)% and (5.73±0.88)% in the blank group, model group and 150 μmol/L TF-TP group, respectively, with a significant difference among the groups (F=206.18, P=0.00), and the apoptosis rate of the cells in the 150 μmol/L TF-TP group was significantly lower than that in the model group (P<0.05). Compared with the blank control group, the relative expression of bax and TF was obviously increased and that of bcl-2 was decreased in the model group; while the expression of bax and TF was lower, and that of bcl-2 was higher in the 150 μmol/L TF-TP group compared with the model group (all at P<0.05). Conclusions Pretreation of TF-TP can lessen cell apoptosis and increase cell survival rate and therefore plays a protective role to blue light-induced human RPE cells possibly by inhibiting bax/bcl-2 apoptotic pathways mediated by TF. Key words: Tissue factor; Human; Retinal pigment epithelium/metabolism; Epithelial cells/ radiation effects; Light; Apoptosis

Protective effects of fluoroquinolones on UV-induced damage of cultured ocular cell lines

Although the fluoroquinolones have strong antibacterial effects, some of them also have adverse ocular effects such as diplopia, uveitis, optic neuropathy, and retinal detachment. The purpose of this study was to determine whether low concentrations of fluoroquinolones can lessen the cytotoxic effects of ultraviolet (UV) light on different kinds of cultured ocular cells. We studied cultured human corneal endothelial cells (HCECs), a retinal ganglion cell line (RGC-5), a mouse-derived photoreceptor cell line (661W), a human adult retinal pigment epithelial cell line (ARPE-19), primary retinal cells, and primary human RPE cells. Levofloxacin, ciprofloxacin, and clinafloxacin were selected as the fluoroquinolones to test. The viabilities of the 661W, ARPE-19, and hRPE cells were assessed by Cell Counting Kit-8, and that of HCECs, 661W cells, and ARPE-19 cells by double fluorescent staining with Hoechst 33342 and propidium iodide (PI). Damage of retinal primary culture cells was assessed by immunostaining. Intracellular production of reactive oxygen species was measured in ARPE-19 cells by CM-H2DCFDA after UV light exposure. An activation of caspase by UV light in ARPE-19 cells was detected with a caspase-3/7 assay kit. UV exposure increased the number of dead cells, and the three fluoroquinolones tested suppressed this increase. Fluoroquinolones also protected the cells against the hydroxyperoxide (H2O2)-induced cell damage. Moreover, the fluoroquinolones decreased the production of reactive oxygen species and the activity of caspase-3/7, and low concentrations of fluoroquinolones reduced the oxidative stress in cultured ocular cell lines. We conclude that fluoroquinolones may have protective effects in these cells against UV exposure.

Hydroxychloroquine for treatment of rheumatoid arthritis: multifocal electroretinogram and laser flare-cell photometry study

PurposeTo evaluate early changes in multifocal electroretinogram (mfERG) and subclinical aqueous humor flare and cellularity in patients receiving hydroxychloroquine (HCQ) as treatment for rheumatoid arthritis.MethodsTen patients receiving treatment with HCQ and no ophthalmic symptoms were enrolled. After complete ocular examination, mfERG and laser flare-cell photometry were performed. Patients were also divided into two subgroups with HCQ cumulative dose (CD) higher or lower than 500 g. Results obtained were compared with a control group of ten healthy subjects and statistical analysis was performed.ResultsIn patients receiving HCQ treatment, mfERG P1-wave in ring 2 showed a significant reduction in amplitude and a significant increase in latency compared to healthy control subjects, respectively resulting in 1.143 μV vs 1.316 μV (P=0.040) and 38.611 ms vs 36.334 ms (P=0.024). These changes are highly related to CD. Furthermore, when using the laser flare-cell photometry, a significant increase in aqueous humor flare and cellularity was shown in patients with CD higher than 500 g, resulting in a mean value of 14.4 ph/ms compared to 8.1 ph/ms in patients with CD lower than 500 g (P=0.0029). These reports appear highly related to CD (P=0.001). Receiver operating characteristic curve analysis showed mfERG P1-wave amplitude in ring 2 as the most sensitive value in detecting early HCQ-related retinopathy.ConclusionMfERG was shown to be a very sensitive test in detecting early retinal toxicity and should be used for the screening of patients receiving HCQ treatment. Although less sensitive, laser flare-cell photometry can provide further information to evaluate early toxic retinal cell damage.

HMGB1 siRNA can reduce damage to retinal cells induced by high glucose in vitro and in vivo.

BackgroundDiabetic retinopathy (DR), one of the most common complications of late-phase diabetes, is associated with many risk factors, among which continuous low-grade inflammation is one of the principal ones. As such, lowering inflammation levels and maintain the viability of human retinal endothelial cells (HRECs) are critical for DR therapy. HMGB1 is a well-known proinflammatory cytokine. However, whether HMGB1 small interfering RNA (siRNA) can protect retina cells under a high-glucose environment from morphological changes and functional abnormalities remain undetermined. We aimed to investigate the effect of HMGB1 siRNA on retinal cells in DR.Materials and methodsA total of 80 adult Wistar rats were randomly divided into four groups (n=20 each): normal control, diabetes mellitus (DM), scrambled (Scr) siRNA, and HMGB1 siRNA. Rats in the DM, Scr siRNA, and siRNA groups were established by intraperitoneal injection of streptozotocin. At 16 weeks after injection, rats in the siRNA and Scr-siRNA groups were intravitreally injected with 2 μL HMGB1 siRNA and 2 μL Scr-siRNA, while rats in the control and DM groups were intravitreally injected with the same dose of sterile saline. At 1 week after injections, we performed the following experiments. Immunohistochemical staining and real-time quantitative polymerase chain reaction were performed to test HMGB1 protein and messenger RNA expression in retinas. We performed TUNEL assays to detect retinal cell apoptosis and electroretinography to detect retinal function. In HRECs treated with high glucose, proliferation, morphology, apoptosis, super-oxide dismutase (SOD), and reactive oxygen species production were detected. Western blot was applied to determine the expressions of HMGB1 and its related protein and apoptosis protein.ResultsIntravitreal injection of HMGB1 siRNA reduced protein and messenger RNA expression of HMGB1 (both P<0.05). Intravitreal injection of HMGB1 siRNA reduced apoptosis of retinal cells (P<0.05), protected morphological changes in the retina, and improved the function of the retina (P<0.05). In HRECs treated with high glucose, HMGB1 siRNA pretreatment increased cell viability, reduced cell apoptosis, and reduced oxidative damage to cells (all P<0.05). Western blot detection found that HMGB1 siRNA pretreatment can inhibit the expression of cleaved caspase 3 and improve the expression of BCL2 (P<0.05). HMGB1 and NFκB expression increased in a time-dependent manner in the high-glucose environment and IKKβ and NFκB protein expression decreased significantly after HMGB1 silencing.ConclusionAs a therapeutic target, HMGB1 siRNA can reduce retinal cell damage induced by high glucose in vitro and in vivo and delay DR progress through the HMGB1–IKKβ–NFκB signaling pathway.

Assessing Retinal Hazardous Effects from Phosphor Converted Light Emitting Diode (LED) Lighting with Different Correlated Color Temperature (CCT)

Due to the rapid growth in the use of blue-light-based electrical panels and much brighter lighting environments, the socioeconomic impact by retinal light injury is critical. Understanding the material property and mechanisms underlying this hazard is important for both effective and user-friendly product development. The InGaN based blue LED has been applied to excite the yellow phosphor (Y3Al5O12:Ce3+) for white light generation. In this study, custom-made phosphor-converted white light emitting diode (pc-WLED) with correlated color temperature (CCT) ranging from 2700K to 6500K were used for exposure treatments to assess the potential retinal injury. We examined LED induced retinal neuronal cell damage in a rat model through functional and histopathological measurements. Electroretinography (ERG), hematoxylin and eosin (H&amp;E) staining, and transmission electron microscopy (TEM) were used for pathological examinations. The experimental results indicate that blue-rich-LED light could induce more photochemical injury to the retina after the exposure. The results of this study suggest that retinal injury is mainly induced by photosensitizer-and photopigment-mediated oxidative stress with color temperature dependent effect, and users should be more aware of this effect before switching to LED lamps for domestic lighting.

Light-emitting-diode induced retinal damage and its wavelength dependency in vivo.

To examine light-emitting-diode (LED)-induced retinal neuronal cell damage and its wavelength-driven pathogenic mechanisms. Sprague-Dawley rats were exposed to blue LEDs (460 nm), green LEDs (530 nm), and red LEDs (620 nm). Electroretinography (ERG), Hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunohistochemical (IHC) staining, Western blotting (WB) and the detection of superoxide anion (O2-·), hydrogen peroxide (H2O2), total iron, and ferric (Fe3+) levels were applied. ERG results showed the blue LED group induced more functional damage than that of green or red LED groups. H&E staining, TUNEL, IHC, and TEM revealed apoptosis and necrosis of photoreceptors and RPE, which indicated blue LED also induced more photochemical injury. Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and iron-overload were associated with retinal injury. WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency. The study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.

The inhibition of NOTCH2 reduces UVB-induced damage in retinal pigment epithelium cells.

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly. The pathogenesis of dry AMD remains indistinct and the mechanism of retinal pigment epithelium (RPE) cells death in dry AMD is controversial. The aim of the present study was to investigate the functions of Notch signaling in ultraviolet B (UVB)-induced damage of RPE cells. It was identified that, in RPE cells, UVB increased intracellular reactive oxygen species (ROS) and induced cell apoptosis. In addition, UVB activated Notch signaling in a dose dependent manner. Surprisingly, NOTCH2, but not NOTCH1, was demonstrated to be the major Notch receptor in RPE cells. Under normal conditions, the inhibition of NOTCH2 reduced cell growth and cell migration, but had no impact on intracellular ROS and cell apoptosis. However, in the presence of UVB, the inhibition of NOTCH2, but not NOTCH1, attenuated intracellular ROS and cell apoptosis. The function of Notch signaling involved in UVB damage of RPE cells may not only be significant to understanding the pathogenesis of AMD (especially dry AMD), but also useful for designing effective therapeutic agents for dry AMD.

Basigin can be a therapeutic target to restore the retinal vascular barrier function in the mouse model of diabetic retinopathy.

Despite the advance in medical technology, diabetic retinopathy (DR) is still an intractable disease which leads to the damage of retinal cells and finally the visual loss. Impairment of retinal vascular barrier triggered by an admixture of multiple inflammatory cytokines is a core of pathophysiology of DR. Therefore, the molecules involved commonly in multiple cytokines-induced impairment of vascular barrier would be the targets of curative treatment of DR. Here, we demonstrate that basigin, a transmembrane molecule expressed in neural barrier-forming endothelial cells, is the molecule essential for vascular barrier impairment which is shared by various triggers including VEGF, TNFα and IL-1β. In vitro data with neural microvascular endothelial cells indicated that stimulation with cytokines decreases the levels of claudin-5 in cell membranes and consequently impairs the barrier function in a manner dependent on the interaction of claudin-5 with basigin and caveolin-1. In addition, the increased vascular permeability in retinas of streptozotocin-induced diabetic mice was shown to be clearly normalized by intravitreous injection of siRNAs specific for basigin. This study has highlighted basigin as a common essential molecule for various stimuli-induced impairment of retinal vascular barrier, which can be a target for strategies to establish a curative treatment of DR.

Dock3-NMDA receptor interaction as a target for glaucoma therapy.

Glaucoma is a neurodegenerative disease of the eye and it is one of the major causes of blindness. Glaucoma is usually associated with elevated intraocular pressure (IOP) and the current therapy focuses on reduction of IOP. However, neuroprotective strategies could also be beneficial for treatment of glaucoma because the pathology of the disease involves retinal ganglion cell (RGC) death and damage to the optic nerve. Dedicator of cytokinesis 3 (Dock3) is an atypical guanine exchange factor (GEF) that belongs to a family of Dock proteins, Dock1-11. Dock3 exerts neuroprotective effects on the retina and optic nerve, and studies revealed that some of the Dock3-mediated effects are GEF-independent. One of these mechanisms is that Dock3 directly binds to the GluN2B subunit of the N-methyl-D-aspartate (NMDA) receptor. Upon stimulation by NMDA or optic nerve crush, overexpression of Dock3 promotes internalization and degradation of the NMDA receptor in the retina in vivo. It is suggested that this process is mediated by inhibition of Fyn, a Src family tyrosine kinase. Reduction in NMDA receptor expression results in decreased excitotoxic damage and oxidative stress, thereby promoting RGC survival. In this review, we discuss the therapeutic potential of neuroprotection for glaucoma and the effects of Dock3 on NMDA receptors. We also discuss apoptosis signal-regulating kinase 1 (ASK1), a member of mitogen-activated protein kinase kinase kinase that is a key regulator of cellular responses to oxidative stress, as an innovative therapeutic target for glaucoma.

Specific Inner Retinal Layer Cell Damage in an Autoimmune Glaucoma Model Is Induced by GDNF With or Without HSP27.

Previously, immunization of rats with ocular antigens induced retinal ganglion cell (RGC) degeneration. We investigated the effect of immunization with glial cell line-derived neurotrophic factor (GDNF) or GDNF in combination with heat shock protein 27 (GDNF+HSP) on RGCs and other retinal cells. Rats were immunized with GDNF or GDNF+HSP. After 4 weeks, retinas were stained with Brn-3a and NeuN to quantify RGCs. GFAP and vimentin staining were used to investigate macroglia. Microglia were marked with Iba1 and ED1. Amacrine cells were labeled with parvalbumin and ChAT. Photoreceptors were evaluated with rhodopsin and opsin staining and bipolar cells with PKCα and recoverin. For these cell types, Western blotting was also performed. Retinas of immunized animals showed a significant loss of Brn-3a+ and NeuN+ RGCs. No significant changes could be observed in regard to macroglia. An increase in Iba1+ microglia was detected in both groups, but little change in regard to activated microglia. A loss of cholinergic amacrine cells was seen in the GDNF+HSP group by immunohistochemistry and in both groups via Western blot analysis. AII amacrine cells, bipolar cells, and photoreceptors were not affected. Immunizations led to loss of RGCs and cholinergic amacrine cells and a strong increase in microglial cells. Our data suggest that RGC loss is the consequence of immunization with GDNF. Astrocyte activity and its neuroprotective effects seem to be inhibited by GDNF immunization. We presume more complex interactions between GDNF and HSP27 because no additive effects could be observed.

Immune modulation by MANF promotes tissue repair and regenerative success in the retina.

Regenerative therapies are limited by unfavorable environments in aging and diseased tissues. A promising strategy to improve success is to balance inflammatory and anti-inflammatory signals and enhance endogenous tissue repair mechanisms. Here, we identified a conserved immune modulatory mechanism that governs the interaction between damaged retinal cells and immune cells to promote tissue repair. In damaged retina of flies and mice, platelet-derived growth factor (PDGF)-like signaling induced mesencephalic astrocyte-derived neurotrophic factor (MANF) in innate immune cells. MANF promoted alternative activation of innate immune cells, enhanced neuroprotection and tissue repair, and improved the success of photoreceptor replacement therapies. Thus, immune modulation is required during tissue repair and regeneration. This approach may improve the efficacy of stem-cell-based regenerative therapies.

Two new phenols from Lysimachia patungensis

Two new phenols, methyl 3-(2-O-β-d-glucopyranosyl-3-hydroxy-5-methoxyphenyl) propionate (1) and myricetin-3,3′,5′-tri-O-α-l-rhamnopyranoside (2), together with six known phenols compounds (3–8), were isolated from the whole plant of Lysimachia patungensis Hand.-Mazz. Their structures were elucidated on the basis of the interpretation of spectroscopic data, viz., ESI-MS, HR-TOF-MS, UV, IR, and NMR. All the known phenols were isolated from the genus Lysimachia for the first time. A preliminary bioassay revealed that compounds 3 and 7 exhibited significant protective effects against hydrogen peroxide-induced damage in human retinal endothelial cells (HRECs) with the concentration of 10 μM, respectively. Compound 1 showed moderate activity against the HRECs damage at 100 μM.

Thrombolysis of plasmin-ΔK on photochemically induced branch retinal vein occlusion after intravitreal injection in rats

Background Retinal vein occlusion is a common retinal vascular diseases.Thromblysis and anticoagulation therapies are main approaches.However, systemic thrombolysis is relatively inefficient, and it often enhances the risk of hemorrhage. Objective This study was to investigate the therapeutic effects of PLM-ΔK, a kringle deficiency mutant of plasmin, on photochemically induced branch retinal vein occlusion (BRVO) after intravitreal injection. Methods BRVO models were established by the combination of caudal vein injection of Rose Bengal with argon laser radiation of periphery area of retinal veins in SD rats.Forty model rats were randomized into balance salt solution (BSS) group and 0.01 U, 0.02 U, 0.03 U PLM-ΔK group, and 10 μl corresponding drug was intravtreally injected 12 hours after modeling.Ophthalmoscopy and fundus fluorescein angiography (FFA) were performed to observe the change of retinal veins.The animals were sacrificed 3 days after intravitreal injection, and hematoxylin and eosin staining was used for the histopathological and ultrastructural examination of retinas.The retina of the rats was isolated for the stretched preparation of retina.The expressions of fibronectin (FN) and laminin (LN) in eyeball wall were assayed by immunofluorescence technology.The use and care of the animals complied with Statement of the Association for Research in Vision and Ophthalmology. Results The revascularization of over 2 retinal veins was found in 0, 3, 6 and 8 rats in the BBS group and 0.01 U, 0.02 U, 0.03 U PLM-ΔK group 3 days after intravitreal injection, respectively, showing a significant difference among the groups (χ2=9.635, P=0.022), and the rat number with revascularization in 0.01 U PLM-ΔK group was not significantly different from that in BSS group (Z=-1.558, P=0.119), but the difference between 0.03 U PLM-ΔK group and 0.01 U PLM-ΔK group was significant (Z=-2.762, P=0.006). In the third day after intravitreal injection, retinal vein thrombus were found in the BSS group under the light microscope, and angiogenesis was seen on the retinal flatmount nuclear.In the 0.03 U PLM-ΔK group, posterior vitreal detachment was exhibited under the light microcope, and no retinal new vessel and cell damage were seen.FN was strongly expressed in the inner limiting membrane (ILM) layer, photocyte layer, outer limiting membrane (OLM) layer, choroid and scleral layer, and LN was expressed mainly in the ILM, OLM and scleral layer in the BSS group.However, the expression intensities of FN and LN were obviously weakened in the 0.03 U PLM-ΔK group. Conclusions Intravitreal injection of PLM-ΔK can enhance the reperfusion of occluded branch retinal vein and serve as a potential therapeutic drug for BRVO.Also it can permeate into choroid after intravitreal injection to degradate FN and LN. Key words: Retinal vein occlusion/therapy; Fibrinolytic agents/administration d Intravitreal injection; Thrombolytic therapy/methods; Disease models, animal; SD rats

The pro-inflammatory role of high-mobility group box 1 protein (HMGB-1) in photoreceptors and retinal explants exposed to elevated pressure

To determine the role of high-mobility group box 1 protein (HMGB-1) in cellular and tissue models of elevated pressure-induced neurodegeneration, regeneration, and inflammation. Mouse retinal photoreceptor-derived cells (661W) and retinal explants were incubated either under elevated pressure or in the presence of recombinant HMGB-1 (rHMGB-1) to investigate the mechanisms of response of photoreceptors. Immunohistochemistry, western blotting, and the quantitative real-time PCR were used to examine the expression levels of immunological factors (eg, HMGB-1, receptor for advanced glycation end products (RAGE)), Toll-like receptors 2 and 4 (TLR-2, TLR-4), apoptosis-related factors (eg, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad)) as well as cytokine expression (eg, tumor necrosis factor alpha (TNF-α), interleukin (IL)-4, IL-6, and vascular endothelial growth factor (VEGF)). The data revealed increased the expression of HMGB-1 and its receptors RAGE, TLR-2, and TLR-4, and TNF-α as well as pro-apoptotic factors (eg, Bad) as well as apoptosis in 661W cells exposed to elevated pressure. Co-cultivation of 661W cells with rHMGB-1 increased the expression levels of pro-apoptotic Bad and cleaved Caspase-3 resulting in apoptosis. Cytokine array studies revealed an increased release of TNF-α, IL-4, IL-6, and VEGF after incubation of 661W cells with rHMGB-1. Upregulation of HMGB-1, TLR-2, and RAGE as well as anti-apoptotic Bcl-2 expression levels was found in the retinal explants exposed to rHMGB-1 or elevated pressure. The results suggest that HMGB-1 promotes an inflammatory response and mediates apoptosis in the pathology of photoreceptors and retinal homeostasis. HMGB-1 may have a key role in ongoing damage of retinal cells under conditions of elevated intraocular pressure.