Unveiling Drivers of Retinal Degeneration in RCS Rats: Functional, Morphological, and Molecular Insights.

Retinal degenerative diseases, including age-related macular degeneration and retinitis pigmentosa, significantly contribute to adult blindness. The Royal College of Surgeons (RCS) rat is a well-established disease model for studying these dystrophies; however, molecular investigations remain limited. We conducted a comprehensive analysis of retinal degeneration in RCS rats, including an immunodeficient RCS (iRCS) sub-strain, using ocular coherence tomography, electroretinography, histology, and molecular dissection using transcriptomics and immunofluorescence. No significant differences in retinal degeneration progression were observed between the iRCS and immunocompetent RCS rats, suggesting a minimal role of adaptive immune responses in disease. Transcriptomic alterations were primarily in inflammatory signaling pathways, characterized by the strong upregulation of Tnfa, an inflammatory signaling molecule, and Nox1, a contributor to reactive oxygen species (ROS) generation. Additionally, a notable decrease in Alox15 expression was observed, pointing to a possible reduction in anti-inflammatory and pro-resolving lipid mediators. These findings were corroborated by immunostaining, which demonstrated increased photoreceptor lipid peroxidation (4HNE) and photoreceptor citrullination (CitH3) during retinal degeneration. Our work enhances the understanding of molecular changes associated with retinal degeneration in RCS rats and offers potential therapeutic targets within inflammatory and oxidative stress pathways for confirmatory research and development.

Fibronectin binds integrin α5ß1 to regulate macular neovascularization through the Wnt/ß-catenin signaling pathway.

Age-related macular degeneration (AMD) is a progressive, degenerative disease of the macula. The formation of macular neovascularization (MNV) and subretinal fibrosis of AMD is the most classic cause of the loss of vision in older adults worldwide. While the underlying causes of MNV and subretinal fibrosis remain elusive, the common feature of many common retinal diseases is changes the proportions of protein deposition in extracellular matrix (ECM) when compared to normal tissue. In ECM, fibronectin (FN) is a crucial component and plays a pivotal part not only in fibrotic diseases but also in the process of angiogenesis. The study aims to understand the role of ligand FN and its common integrin receptor α5ß1 on MNV, and to understand the molecular mechanism involved. To study this, the laser-induced MNV mouse model and the rhesus macaque choroid-retinal endothelial cell line (RF/6A) chemical hypoxia mode were established, and the FN-α5ß1 expression levels were detected by immunohistochemistry (IHC) and quantitative real-time PCR analysis (qRT-PCR). Fibronectin expression was silenced using small interfering RNA (siRNA) targeting FN. The tube formation and vitro scratch assays were used to assess the ability to form blood vessels and cell migration. To measure the formation of MNV, immunofluorescence, and Western blot assays were used. These results revealed that the expressions of FN and integrin α5ß1 were distinctly increased in the laser-induced MNV mouse model and in the RF/6A cytochemically induced hypoxia model, and the expression tendency was identical. After the use of FN siRNA, the tube formation and migration abilities of the RF/6A cells were lower, the ability of endothelial cells to proliferate was confined and the scope of damage caused by the laser in animal models was significantly cut down. In addition, FN gene knockdown dramatically inhibited the expression of Wnt/ß-catenin signal. The interaction of FN with the integrin receptor α5ß1 in the constructed model, which may act through the Wnt/ß-catenin signaling pathway, was confirmed in this study. In conclusion, FN may be a potential new molecular target for the prevention and treatment of subretinal fibrosis and MNV.

Candidalysin amplifies the immune inflammatory response in Candida albicans keratitis through the TREM-1/DAP12 pathway.

Candidalysin is a fungal peptide toxin secreted by Candida albicans hyphae during invasion into epithelial cells. In Candida albicans-infected mucosa, candidalysin causes epithelial cell damage and activates downstream inflammatory responses, especially the release of inflammatory cytokines. However, the role of candidalysin in Candida albicans corneal keratitis remains unexplored. Moreover, it remains unclear whether candidalysin regulates the inflammatory response through the TREM-1/DAP12 pathway in Candida albicans corneal keratitis. In this study, we determined the expression pattern of TREM-1 in a mouse model of Candida albicans corneal keratitis and investigated the molecular mechanism underlying the inflammatory response regulation by candidalysin. The corneal keratitis model was established in C57BL/6 mice. In the GF9 group, mice were pretreated and then treated with the TREM-1 inhibitor GF9; in the candidalysin group, mice were treated with peptide candidalysin; and in the PD98059 group, mice were pretreated with the ERK inhibitor PD98059. Slit-lamp photography, clinical scoring, PCR, western blotting and immunofluorescence assay were performed to observe disease response and GF9 therapeutic efficacy. Pretreatment with candidalysin or PD98059 was performed before Candida albicans infection. GF9 treatment reduced the expression of TREM-1 and cytokines in the infected mouse cornea, whereas candidalysin treatment increased the expression of TREM-1, p-ERK, and cytokines, and this increase was inhibited by GF9. The candidalysin-induced increment of TREM-1, p-ERK, and cytokines was inhibited by PD98059 pretreatment. These data suggest that candidalysin can initiate inflammatory response in Candida albicans corneal keratitis through the TREM-1/DAP12 pathway and can regulate cytokine expression by enhancing ERK phosphorylation.

Inhibition of AIF-1 alleviates laser-induced macular neovascularization by inhibiting endothelial cell proliferation via restrained p44/42 MAPK signaling pathway.

Age-related macular degeneration (AMD) is a leading blinding disease worldwide, and macular neovascularization (MNV) is a common complication encountered in the advanced stages of AMD. While the underlying causes of MNV remain elusive, aberrant multiplication of choroidal endothelial cells (CECs) and increased vascular endothelial growth factor (VEGF) are thought to play significant roles in the occurrence and development of MNV. Allograft inflammatory factor-1(AIF-1) is a crucial regulatory factor of vascular tubular structure formation and growth, involving the proliferation and migration of vascular endothelial cells and various tumor cells. This study aimed to understand how AIF-1 effects the proliferation of CECs and the subsequent progression of MNV. To study this, a mouse MNV model was established through laser injury, and the AIF-1 expression levels were then measured using western blot and immunohistochemistry. AIF-1 siRNA was intravitreally injected to silence AIF-1 gene expression. Western blot and choroidal flat mount were performed to measure the progression of MNV and proliferation of the CECs. These results showed that the protein expression of AIF-1 was significantly elevated in the laser-induced mouse MNV model, and the expression trend was consistent with VEGF. The protein level of AIF-1 was significantly decreased after the intravitreal injection of AIF-1 siRNA, the damage range of laser lesions was significantly reduced, and the proliferation of endothelial cells was inhibited. Knockdown of the AIF-1 gene significantly inhibited the expression of mitogen-activated protein kinase p44/42 in MNV lesions. In summary, this research demonstrates that AIF-1 promoted MNV progression by promoting the proliferation of CECs and that silencing AIF-1 significantly ameliorates MNV progression in mouse models, which may act through the p44/42 MAPK signaling pathway. AIF-1 could be a new potential molecular target for MNV.

Biomimetic, Injectable, and Self-Healing Hydrogels with Sustained Release of Ranibizumab to Treat Retinal Neovascularization.

Retinal neovascularization (RNV) is a typical feature of ischemic retinal diseases that can lead to traction retinal detachment and even blindness in patients, in which the vascular endothelial cell growth factor (VEGF) plays a pivotal role. However, most anti-VEGF drugs currently used for treating RNV, such as ranibizumab, need frequent and repeated intravitreal injections due to their short intravitreal half-life, which increases the incidence of complications. Herein, a hydrogel intravitreal drug delivery system (DDS) is prepared by a dynamic Schiff base reaction between aminated hyaluronic acid and aldehyde-functionalized Pluronic 127 for sustained release of ranibizumab. The prepared hydrogel system named HP@Ran exhibits excellent injectability, self-healing ability, structural stability, cytocompatibility, and blood compatibility. According to an in vitro drug release study, the hydrogel system continuously releases the model drug bovine serum albumin for more than 56 days. Importantly, in an in vivo rabbit persistent RNV model, the HP@Ran hydrogel system continuously releases pharmacologically active ranibizumab for more than 7 weeks and also exhibits superior anti-angiogenic efficacy over ranibizumab treatment by decreasing vascular leakage and neovascularization at 12 weeks. Thus, the developed HP@Ran hydrogel system possesses great potential for intravitreal DDS for the treatment of RNV.

High resolution optical coherence elastography of retina under prosthetic electrode.

BACKGROUND: Quantitatively investigating the biomechanics of retina with a retinal prosthetic electrode, we explored the effects of the prosthetic electrode on the retina, and further supplemented data for a potential clinical trial. METHODS: Biomechanical properties were assessed with a high resolution optical coherence tomography (OCT) based elastography (OCE) system. A shaker was used to initiate elastic waves and an OCT system was used to track axial displacement along with wave propagation. Rabbits received surgery to implant the retinal prosthetic electrode, and elastic wave speed was measured before and after implantation; anatomical B-mode images were also acquired. RESULTS: Spatial-temporal maps of each layer in retina with and without prosthetic electrodes were acquired. Elastic wave speed of nerve fiber to inner plexiform layer, inner nuclear to outer nuclear layer, retinal pigmented epithelium layer and choroid to sclera layer without prosthetic electrode were found to be 3.66±0.36, 5.33±0.07, 6.85±0.37, and 9.69±0.24 m/s, respectively. With prosthetic electrode, the elastic wave speed was found to be 4.09±0.26, 5.14±0.11, 6.88±0.70, and 9.99±0.73 m/s, respectively in each layer. CONCLUSIONS: Our results show that the elastic wave speed in each layer of retina is slightly faster with the retinal electrode, and further demonstrate that the retinal prosthetic electrode does not affect biomechanical properties significantly. In the future, we expect OCE technology to be used by clinicians where it could become part of routine testing and evaluation of the biomechanical properties of the retina in response to long term use of prosthetic electrodes in patients.

Evaluation of vitrectomy combined preoperative intravitreal ranibizumab and postoperative intravitreal triamcinolone acetonide for proliferative diabetic retinopathy.

BACKGROUND: To explore the treatment efficacy of the combination of preoperative intravitreal ranibizumab (IVR) and postoperative intravitreal triamcinolone acetonide (IVTA) in patients undergoing pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR). METHODS: A retrospective comparative study was performed on 128 eyes of 128 patients who had PDR and underwent PPV. Patients who received a single PPV were assigned to Group A. Those who received PPV with preoperative IVR were assigned to Group B. Patients in Group C underwent PPV combined preoperative IVR and postoperative IVTA. Intraoperative findings, changes in mean best-corrected visual acuity (BCVA) and postoperative adverse events, were retrospectively evaluated at 6-month follow-up. RESULTS: The incidences of iatrogenic breaks, severe intraoperative bleeding, using long-term internal tamponade agents, recurrent vitreous hemorrhage (VH), and duration of surgery were statistically significantly less in Group B and Group C than in Group A. The postoperative BCVA was statistically significantly better in Groups B and Group C than in Group A, respectively, at 1 month after surgery. The mean 3-month postoperative visual acuity was better in Group C. The incidence of high intraocular pressure (IOP) was significantly higher in Group C at the first postoperative week. There were no statistically significant differences in the incidence of exudative retinal detachment and choroidal detachment among the three groups. CONCLUSION: In patients undergoing PPV for PDR, preoperative IVR significantly reduced the occurrence of intraoperative and postoperative complications, and the combination of preoperative IVR and postoperative IVTA can better improve the postoperative visual outcome.

In Vivo Visualization of Eye Vasculature Using Super-Resolution Ultrasound Microvessel Imaging.

OBJECTIVE: The choroidal vessels, which supply oxygen and nutrient to the retina, may play a pivotal role in eye disease pathogenesis such as diabetic retinopathy and glaucoma. In addition, the retrobulbar circulation that feeds the choroid shows an important pathophysiologic role in myopia and degenerative myopia. Owing to the light-absorbing retinal pigment epithelium (RPE) and optically opaque sclera, choroidal and retrobulbar vasculature were difficult to be observed using clinically accepted optical coherence tomography angiography (OCT-A) technique. Here, we have developed super-resolution ultrasound microvessel imaging technique to visualize the deep ocular vasculature. METHODS: An 18-MHz linear array transducer with compounding plane wave imaging technique and contrast agent - microbubble was implemented in this study. The centroid intensity of each microbubble was detected using image deconvolution algorithm with spatially variant point spread function, and then accumulated in successive frames in order to reconstruct microvasculature. The image deconvolution technique was first evaluated in a simulation study and experimental flow phantoms. The performance was then validated on normal rabbit eyes in vivo. RESULTS: The image deconvolution based super-resolution ultrasound microvessel imaging technique shows good performance on either simulation study or flow phantoms. In vivo rabbit eye study indicated that the micron-level choroidal and retrobulbar vessels around the optic nerve head were successfully reconstructed in multiple 2D views and 3D volume imaging. CONCLUSIONS: Our results demonstrate the capability of using super-resolution ultrasound microvessel imaging technique to image the microvasculature of the posterior pole of the eye. This efficient approach can potentially lead to a routinely performed diagnostic procedure in the field of ophthalmology.

Quantitative confocal optical coherence elastography for evaluating biomechanics of optic nerve head using Lamb wave model.

The mechanosensitivity of the optic nerve head (ONH) plays a pivotal role in the pathogenesis of glaucoma. Characterizing elasticity of the ONH over changing physiological pressure may provide a better understanding of how changes in intraocular pressure (IOP) lead to changes in the mechanical environment of the ONH. Optical coherence elastography (OCE) is an emerging technique that can detect tissue biomechanics noninvasively with both high temporal and spatial resolution compared with conventional ultrasonic elastography. We describe a confocal OCE system in measuring ONH elasticity in vitro, utilizing a pressure inflation setup in which IOP is controlled precisely. We further utilize the Lamb wave model to fit the phase dispersion curve during data postprocessing. We present a reconstruction of Young's modulus of the ONH by combining our OCE system with a Lamb wave model for the first time. This approach enables the quantification of Young's modulus of the ONH, which can be fit using a piecewise polynomial to the corresponding IOP.

Structural and functional assessment after intravitreal injection of ranibizumab in diabetic macular edema.

PURPOSE: To evaluate structure and function improvement in central retina by optical coherence tomography (OCT) and multifocal electroretinography (mf-ERG) in diabetic macular edema (DME) patients after intravitreal injection of ranibizumab (IVR) treatment. METHODS: Twenty-seven eyes in 27 patients with DME received three consecutive monthly injections of IVR (0.05 ml, 10 mg/ml) and as needed thereafter. The clinical parameters of best-corrected visual acuity (BCVA), central foveal thickness (CFT) and mf-ERG were monitored for 6 months before and after IVR. The findings at baseline, 1, 3 and 6 months were analyzed. Correlation and regression analyses were performed on BCVA, CFT, mf-ERG amplitude and implicit time of the N1 and P1 waves. RESULTS: IVR significantly improved visual acuity from the beginning of the treatment (P < 0.05). There were significant decreases in the CFT compared with the baseline after IVR (P < 0.05). The mean amplitude of P1 and N1 in the central ring at all examinations increased significantly compared with the baseline (P < 0.05). The mean P1 and N1 implicit times in the central ring were shortened, but not significantly (P > 0.05). There were significant correlations of BCVA with CFT, P1 and N1 amplitudes in the central retina (P < 0.05). CONCLUSION: In addition to the improvement in BCVA and the reduction in CFT, IVR improved macular retinal function, as assessed by mf-ERG, in diabetic eyes. The combination of OCT and mf-ERG for macular evaluation may better assess DME.

Protein tyrosine phosphatase 1B regulates migration of ARPE-19 cells through EGFR/ERK signaling pathway.

AIM: To evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process. METHODS: ARPE-19 cells were cultured and treated with the siRNA-PTP1B. Expression of PTP1B was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). AG1478 [a selective inhibitor of epidermal growth factor receptor (EGFR)] and PD98059 (a specific inhibitor of the activation of mitogen-activated protein kinase) were used to help to determine the PTP1B signaling mechanism. Western blot analysis verified expression of EGFR and extracellular signal-regulated kinase (ERK) in ARPE-19 cells. The effect of siRNA-PTP1B on cell differentiation was confirmed by immunostaining for α-smooth muscle actin (α-SMA) and qRT-PCR. Cell migration ability was analyzed by transwell chamber assay. RESULTS: The mRNA levels of PTP1B were reduced by siRNA-PTP1B as determined by qRT-PCR assay. SiRNA-PTP1B activated EGFR and ERK phosphorylation. α-SMA staining and qRT-PCR assay demonstrated that siRNA-PTP1B induced retinal pigment epithelium (RPE) cells to differentiate toward better contractility and motility. Transwell chamber assay proved that PTP1B inhibition improved migration activity of RPE cells. Treatment with AG1478 and PD98059 abolished siRNA-PTP1B-induced activation of EGFR and ERK, α-SMA expression and cell migration. CONCLUSION: PTP1B inhibition promoted myofibroblast differentiation and migration of ARPE-19 cells, and EGFR/ERK signaling pathway played important role in migration process.

Natamycin in the treatment of fungal keratitis: a systematic review and Meta-analysis.

AIM: To review published clinical studies examining the effect of natamycin in the treatment of fungal keratitis. METHODS: We selected the publications in CENTRAL, MEDLINE, EMBASE, CNKI, and CBM. This study systematically reviewed published randomized controlled trials (RCTs) that compared natamycin to other antifungal agents, and conducted feasible Meta-analysis of efficacy results using Revman 5.2 software. RESULTS: We included seven trials which were mainly carried out in developing countries of Asia, with five trials conducted in India, one each in China and Bangladesh. A total of 804 participants were randomized to following comparisons: 2% econazole versus 5% natamycin showed little difference in the effects of treatment of fungal keratitis [RR=0.99, 95% confidence interval (CI), 0.8 to 1.21]; chlorhexidine gluconate versus 5% natamycin indicated that the results on healing of the ulcer at 21d was less conclusive (RR=0.77, 95% CI, 0.55 to 1.08; I (2)=0%); 1% voriconazole versus 5% natamycin suggested that natamycin treatment appeared to be significantly better outcomes than voriconazole (regression coefficient =-0.18 logMAR; 95% CI, -0.30 to -0.05; P=0.006), especially in Fusarium cases (regression coefficient=-0.41 logMAR; 95% CI, -0.61 to -0.20; P<0.001); natamycin versus fluconazole showed a significant difference in cure rate (χ(2)=5.048, P<0.05) and natamycin group was more effective than fluconazole in average period of therapy (t=7.94, P<0.01). CONCLUSION: Natamycin was a preferable choice in the treatment of fungal keratitis, especially in the early period of Fusarium cases.

TREM-1 expression in rat corneal epithelium with Aspergillus fumigatus infection.

AIM: To investigate the expression of triggering receptor expressed on myeloid cells-1 (TREM-1) in the aberrant inflammation within the corneal epithelium at early period of fungal infection. METHODS: A total of 65 Wistar rats were randomly divided into control group, sham group and fungal keratitis (FK) group, in which the cornea was infected by Aspergillus fumigatus (A. fumigatus). After executed randomly at 8, 16, 24, 48 and 72h after experimental model being established, the severity of keratomycosis in rats was scored visually with the aid of a dissecting microscope and slit lamp. Then corneas in three groups were collected to assess the expression of TREM-1 through quantitative reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence technique and Western blot analysis. The correlation between FK inflammation and expression of TREM-1 was also analyzed. RESULTS: Corneal inflammation scores increased with time after fungal infection (F=49.74, P=0.000). The inflammation scores in FK group were obviously higher than those in sham group on the whole (F=137.78, P=0.000). Levels of TREM-1 in the infected rat corneal epithelium had elevated at 8h and peaked at 48h (P<0.001, compared with control group). Western blot analysis also showed an obviously elevated TREM-1 level in rat corneal epithelium at 24h and 48h after fungal infection. Immunofluorescence technique showed that TREM-1 mainly existed in corneal epithelium and infected corneal stoma of rat. TREM-1 protein expression was enhanced after fungal infection. Moreover, severity of FK inflammation was significantly related to TREM-1 expression in FK (r=0.942, P=0.000). CONCLUSION: TREM-1 may contribute to amplify the inflammation in the cornea infected with A. fumigatus and play critical roles in the battle against A. fumigatus in the innate immune responses.

Protein tyrosine phosphatase 1B regulates the activity of retinal pigment epithelial cells.

PURPOSE: To determine whether protein tyrosine phosphatase 1B (PTP1B) is expressed in rat retinal pigment epithelium (RPE) cells, to evaluate whether inhibition of PTP1B contributes to initiation of RPE cells into an active state, and to investigate the signaling pathways involved in this process. METHODS: Rat retinas were detached by trans-scleral injection of 1.4% sodium hyaluronate into the subretinal space. Immunocytochemistry evaluated the expression of PTP1B in RPE cells located at normal and detached retinas. From the cultured RPE cells treated with TCS-401, cell proliferation was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetracolium bromide assay, and the protein expression levels of cyclin A and cyclin D1 were determined. The effect of TCS-401 on cell differentiation was confirmed by immunostaining for α-smooth muscle actin and by western blot. Cell migration activity and PTP1B signaling mechanism were determined. Migration Assay was used to evaluate cell migration activity. PTP1B signaling mechanism was determined by use of PD98059 and LY294002. RESULTS: PTP1B was expressed in the RPE layer of the normal retina. After retinal detachment, weak immunolabeling of PTP1B was seen in the RPE cells. TCS-401 promoted the proliferation and expression of cyclin A and cyclin D1 in RPE cells. TCS-401 induced RPE cells to differentiate toward better contractility and motility. A migration assay proved that inhibiting PTP1B improved the migratory activity of RPE cells. TCS-401 activated extracellular signal-regulated kinase (Erk) and protein kinase B (Akt) phosphorylation. Pretreatment with PD98059 and LY294002 abolished TCS-401-induced activation of Erk, Akt, cell proliferation, and cell migration. CONCLUSIONS: PTP1B may be involved in regulating the active state of RPE cells. The inhibition of PTP1B promoted the proliferation, myofibroblast differentiation, and migration of RPE cells, and MEK/Erk and PI3K/Akt signaling pathways played important roles in the proliferation and migration process.

MiR-145 suppressed human retinoblastoma cell proliferation and invasion by targeting ADAM19.

MicroRNAs (miRNAs) play critical roles in retinoblastoma (RB) initiation and progression, aberrant expression of miR-145 had been frequently reported in cancer studies. However, the role and mechanism of its function in RB is still unclear. In this study, our data showed that miR-145 was downregulated in RB tissues and cell lines. Overexpression of miR-145 suppressed RB cell proliferation, migration and invasion in vitro. ADAM19 was identified as a direct target of miR-145. Silencing of ADAM19 significantly inhibited RB cell proliferation, migration and invasion. In addition, a reverse correlation between miR-145 and ADAM19 expression was noted in RB tissues. Taken together, these findings suggested that miR-145 functions as a tumor suppressor in RB by directly targeting ADAM19. miR-145 could be an anticancer therapeutic target for RB patients.

Role of TREM-1 in response to Aspergillus fumigatus infection in corneal epithelial cells.

Triggering receptor expressed on myeloid cells-1 (TREM-1) is a cell surface receptor that is highly expressed in inflammatory lesions caused by infectious agents such as bacteria and fungi and amplifies immune responses. The aim of the current study was to investigate TREM-1 expression in corneal epithelial cells infected by Aspergillus fumigatus (A. fumigatus) and evaluate its role. In this study, infection with A. fumigatus upregulated TREM-1 expression in corneal epithelial cells both in vitro and in vivo. Furthermore, treatment with the antagonistic peptide of TREM-1 decreased the levels of inflammatory cytokines that were enhanced by the fungal infection. We speculated that cross-talk occurs between TREM-1 and Toll-like receptor-4 (TLR-4) in cornea fungal infection. Inhibitors of TLR-4 and myeloid differentiation factor 88 (MyD88) could partially inhibit the upregulation of TREM-1 induced by A. fumigatus respectively. In addition, TLR-4 blockade enhanced the inhibitory effect of the antagonistic peptide of TREM-1 on A. fumigatus-induced inflammation. These findings suggest that TREM-1 plays critical roles in fungal infection, and targeting it may represent a novel therapeutic strategy for patients with fungal keratitis.

Manganese-enhanced MRI optic nerve tracking: effect of intravitreal manganese dose on retinal toxicity.

The aim of this study was to provide data on the dose dependence of manganese-enhanced MRI (MEMRI) in the visual pathway of experimental rats and to study the toxicity of MnCl2 to the retina. Sprague-Dawley rats were intravitreally injected with 2 µL of 0, 10, 25, 50, 75, 100, 150 and 300 mM MnCl2, respectively. The contrast-to-noise ratio (CNR) of MEMRI for optic nerve enhancement was measured at different concentrations of MnCl2. Simultaneously, the toxicity of manganese was evaluated by counting retinal ganglion cells and by retinal histological examination using light microscopy and transmission electron microscopy. The CNR increased with increasing concentration of MnCl2 up to 75 mM. Retinal ganglion cell densities were reduced significantly when the concentration of MnCl2 in the intravitreal injection was equal to or greater than 75 mM. Increasing numbers of ribosomes in retinal ganglion cells were first detected at 25 mM of MnCl2. The retinal toxicity of MnCl2 at higher concentration also included mitochondrial pathology and cell disruption of retinal ganglion cells, as well as abnormalities of photoreceptor and retinal pigment epithelium cells. It can be concluded that intravitreal injection of MnCl2 induces retinal cell damage that appears to start from 25 mM. The concentration of MnCl2 should not exceed 25 mm through intravitreal injection for visual pathway MEMRI in the rat.

Epidemiological characteristics and risk factors of diabetic retinopathy in type 2 diabetes mellitus in Shandong Peninsula of China.

AIM: To determine the epidemiological characteristics and estimate the risk factors of diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM) in Shandong Peninsula of China. METHODS: The cases of T2DM admitted to Affiliated Hospital of Medical College of Qingdao University, Shandong Province, China, from January 2006 to December 2010 were retrospectively reviewed. The epidemiological characteristics of DR were estimated. The cases were divided into two groups according to degrees of retinopathy: non-DR group and DR group. Logistic regression analysis was used to study the related risk factors of DR. RESULTS: The prevalence of DR in patients with T2DM was 25.08% (834/3326). There was significant difference between the average age for men (59.08±15.43 years) and for women (62.92±18.19 years, P=0.0021). The majority of DR occurred in women (female: male ratio=1.76:1, P<0.0001). The incidence rate of DR in urban (489/834) was higher than that in rural area (345/834, P<0.0001). In 834 DR patients, the mean duration of T2DM was 8.90±4.15 years (range: 0-16 years); 440 people (52.76%) had received varying degrees of health education about prevention and primary care of DM; and 473 people (56.71%) suffered from other DM complications confirmed at the same time. In addition, the incidence rate of monocular (551/3326) and binocular retinopathy (283/3326) were statistically different (P<0.0001). Factors associated (P<0.05) with the presence of DR included old age, lower health educational level, intraocular surgery history, longer duration of T2DM, accompanying with other DM complications, no standard treatment procedure, lower body mass index (BMI) and higher fasting plasma glucose (FPG), glycated hemoglobin A(1)C (HbA(1)C), urine albumin (UA), total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C). The risk factors (P<0.05) independently associated with the presence of DR were: longer duration of T2DM, lower health educational level, higher FPG, higher UA, lower BMI and higher TC. CONCLUSION: DR is highly prevalent in the patients with T2DM in Shandong Peninsula of China. Besides blood glucose, many factors are associated with the present and development of DR.

The effects of sodium orthovanadate-induced phosphatase inhibition on rat retinal pigment epithelium cell activity.

PURPOSE: The purpose of this study was to assess the contribution of sodium orthovanadate (SOV)-induced phosphatase inhibition to the activation of rat retinal pigment epithelium (RPE) cells. METHODS: Confluent cultures of rat RPE cells were treated with the general phosphatase inhibitor SOV. The effects of SOV on the cell cycle were determined by flow cytometry and protein detection of cyclin A and cyclin D1, two different cell cycle regulatory factors. The effects of SOV on cell differentiation were confirmed by immunostaining for α-smooth muscle actin (α-SMA). A migration assay was used to evaluate the effects of SOV on cell migration. RESULTS: SOV could accelerate the cell cycle of RPE cells. Western blotting showed that SOV significantly increased the expression of cyclin A and cyclin D1 in a dose-dependent fashion. The results of α-SMA staining and western blotting demonstrated that SOV induced RPE cells to differentiate toward better contractility and motility. The migration assay indicated that SOV improved the migration activity of RPE cells. CONCLUSIONS: Sodium orthovanadate can improve proliferation, differentiation, and migration of rat RPE cells and can also induce the reentry of contact-inhibited rat RPE cells into the cell cycle.

[The effect of rapamycin liposome gutta inhibiting rat corneal neovascularization].

OBJECTIVE: To explore the inhibiting effect of rapamycin (RAPA) on corneal neovascularization (CNV) of rats and the functional mechanism. METHODS: A design group was adopted. 102 Wistar rats were divided into four groups at random, including rapamycin liposome treated group (24 rats), the rapamycin solved in bean oil treated group (24 rats), blank liposome treated group (24 rats), blank treated group (24 rats) and normal control group (6 rats). All right eyes of 96 rats were induced by alkali cauterization. Rapamycin liposome were prepared by thin film hydration and the major factors were studied by the method of orthogonal design. After alkali burn, cauterized rats were observed by slitlamp biomicroscope every day. On the 1st, 4th, 7th, 14th days after operation, the expression of HIF-1alpha and VEGF were examined by immunohistochemical method and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The analysis of variance and q test groups for analysis were adopted to analyze the results. RESULTS: (1) The bodies of RAPA liposome were intact kinds of spheres, the average diameter was 145.2 nm, and the envelopment rate was 90.02%. (2) After the burn of 14 d, CNV area of B, C, D and E group were (28.289 +/- 0.703), (28.005 +/- 0.801), (20.002 +/- 1.005) and (22.300 +/- 0.853) mm(2) (F = 159.62, P < 0.05). The CNV of both the rapamycin liposome treated group and the rapamycin solved in bean oil group grew slowly and smaller than that of blank liposome treated group and blank treated group (q = 47.80, 46.20, 34.60, 32.90;P = 0.00). While the rapamycin liposome treated group changed more obviously than the rapamycin solved in bean oil group (q = 13.20, P = 0.00). After alkali burn, the expression of HIF-1alpha and VEGF increased dramatically, meanwhile the expression of HIF-1alpha and VEGF were significantly decreased by RAPA. CONCLUSIONS: Liposome body is an excellent medicine carrier for the RAPA. RAPA can obviously suppress the growth of CNV. The possibly mechanism is weakening VEGF expression by inhibiting the transcription factor HIF-1alpha.