Shiying Li

Tyrosine phosphorylation of VE-cadherin and claudin-5 is associated with TGF-β1-induced permeability of centrally derived vascular endothelium.

Breakdown of the inner blood-retinal barrier and the blood-brain barrier is associated with changes in tight and adherens junction-associated proteins that link vascular endothelial cells. This study aimed to test the hypothesis that transforming growth factor (TGF)-β1 increases the paracellular permeability of vascular endothelial monolayers through tyrosine phosphorylation of VE-cadherin and claudin-5. Bovine retinal and human brain capillary endothelial cells were grown as monolayers on coated polycarbonate membranes. Paracellular permeability was studied by measuring the equilibration of (14)C-inulin or fluorescence-labelled dextran. Changes in VE-cadherin and claudin-5 expression were studied by immunocytochemistry (ICC) and quantified by cell-based enzyme linked immunosorbent assays (ELISA). Tyrosine phosphorylation of VE-cadherin and claudin-5 was studied by ICC, immunoprecipitation and Western blotting. We found that exposure of endothelial cells to TGF-β1 caused a dose-dependent increase in paracellular permeability as reflected by increases in the equilibration of (14)C-inulin. This effect was enhanced by the tyrosine phosphatase inhibitor orthovanadate and attenuated by the tyrosine kinase inhibitor lavendustin A. ICC and cell-based ELISA revealed that TGF-β1 induced both dose- and time-dependent decreases in VE-cadherin and claudin-5 expression. Assessment of cell viability indicated that changes in these junction-associated proteins were not due to endothelial death or injury. ICC revealed that tyrosine phosphorylation of endothelial monolayers was greatly enhanced by TGF-β1 treatment, and immunoprecipitation of cell lysates showed increased tyrosine phosphorylation of VE-cadherin and claudin-5. Our results suggest that tyrosine phosphorylation of VE-cadherin and claudin-5 is involved in the increased paracellular permeability of central nervous system-derived vascular endothelium induced by TGF-β1.

Retinal vascular changes after glial disruption in rats

Glial dysfunction is found in a number of retinal vascular diseases but its link with blood‐retinal barrier (BRB) breakdown remains poorly understood. The present study tested the hypothesis that glial dysfunction is a major contributor to the BRB breakdown that is a hallmark of retinal vascular diseases. We investigated thespecificity of the purportedly selective glial toxin, DL‐α‐aminoadipic acid (DL‐α‐AAA) on different types of ocular cells in vitro and then tested the effect of glial disruption on retinal vasculature after intraocular injection of DL‐α‐AAA or siRNA targeting glutamine synthetase (GS) in rats. DL‐α‐AAA was toxic to astrocytes and Müller cells but not to other types of BRB‐related cells in vitro. Subretinal injection of DL‐α‐AAA disrupted retinal glial cells, induced vascular telangiectasis and increased vascular permeability from 4 days to over 2 months post‐injection. Vascular changes induced by DL‐α‐AAA were observed predominantly in regions of glial disruption, as reflected by reduced expression of GS and increased expression of glial fibrillary acidic protein and vimentin. Confocal microscopy showed changes in all three layers of the retinal vasculature, which co‐localised with areas of Müller cell disruption. Double labeling immunohistochemistry revealed that retinal glial disruption after DL‐α‐AAA injection was accompanied by increased expression of vascular endothelial growth factor and reduced expression of the tight junction protein claudin‐5. Intravitreal injection of GS siRNA induced similar changes in Müller cells and BRB breakdown. Our data are consistent with the hypothesis that glial dysfunction is a primary contributor to the BRB breakdown in retinal vascular diseases.

Systemic Administration of Erythropoietin Inhibits Retinopathy in RCS Rats

Objective Royal College of Surgeons (RCS) rats develop vasculopathy as photoreceptors degenerate. The aim of this study was to examine the effect of erythropoietin (EPO) on retinopathy in RCS rats. Methods Fluorescein angiography was used to monitor retinal vascular changes over time. Changes in retinal glia and vasculature were studied by immunostaining. To study the effects of EPO on retinal pathology, EPO (5000 IU/kg) was injected intraperitoneally in 14 week old normal and RCS rats twice a week for 4 weeks. Changes in the retinal vasculature, glia and microglia, photoreceptor apoptosis, differential expression of p75 neurotrophin receptor (p75NTR), pro-neurotrophin 3 (pro-NT3), tumour necrosis factor-α (TNFα), pigment epithelium derived factor (PEDF) and vascular endothelial growth factor-A (VEGF-A), the production of CD34+ cells and mobilization of CD34+/VEGF-R2+ cells as well as recruitment of CD34+ cells into the retina were examined after EPO treatment. Results RCS rats developed progressive capillary dropout and subretinal neovascularization which were accompanied by retinal gliosis. Systemic administration of EPO stabilized the retinal vasculature and inhibited the development of focal vascular lesions. Further studies showed that EPO modulated retinal gliosis, attenuated photoreceptor apoptosis and p75NTR and pro-NT3 upregulation, promoted the infiltration of ramified microglia and stimulated VEGF-A expression but had little effect on TNFα and PEDF expression. EPO stimulated the production of red and white blood cells and CD34+ cells along with effective mobilization of CD34+/VEGF-R2+ cells. Immunofluorescence study demonstrated that EPO enhanced the recruitment of CD34+ cells into the retina. Conclusions Our results suggest that EPO has therapeutic potentials in treatment of neuronal and vascular pathology in retinal disease. The protective effects of EPO on photoreceptors and the retinal vasculature may involve multiple mechanisms including regulation of retinal glia and microglia, inhibition of p75NTR-pro-NT3 signaling together with stimulation of production and mobilization of bone marrow derived cells.

Efficacy and Safety of Autologous Bone Marrow Mesenchymal Stem Cell Transplantation in Patients with Diabetic Retinopathy

Background/Aims: The treatment options for diabetic retinopathy (DR) are limited. Mesenchymal stem cells (MSCs) are a promising treatment option for diabetes and its complications. In this pilot clinical trial, we evaluated the safety and efficacy of intravenous autologous bone marrow MSCs (ABMSC) for the treatment of DR. Methods: In total, 34 eyes with non-proliferative or proliferative DR (NPDR, n = 19; PDR, n = 15) from 17 patients were analyzed. Treatment involved one intravenous infusion of 3 × 106/kg ABSMCs. The patients’ vital signs were monitored, along with immune and allergic reactions. Treatment efficacy was evaluated via measurements of the following parameters at baseline, and at 1, 3, and 6 months after treatment: the levels of fasting blood glucose (FBG), Hemoglobin A1C (HbA1C), interleukin-6 (IL-6), and hypersensitive C-reactive protein (CRP); best corrected visual acuity (BCVA); and central macular and subfield thickness (via optical computed tomography). Results: ABMSC infusion led to a significant decrease in FBG and CRP levels (P < 0.05). There were no significant differences in HbA1C or IL-6 levels. Sub-group analysis revealed that only eyes in the NPDR group had the macular thickness reductions and a significant improvement in BCVA from baseline (P = 0.006 at 3 months and 0.027 at 6 months), while those in the PDR group did not. There were no acute reactions during the treatment or severe adverse events during the follow-up period. Conclusion: ABSMCs are a potentially safe and effective treatment option for DR, and the optimum therapeutic window appears to be during the NPDR stage.

Treatment of Punctate Inner Choroidopathy with Choroidal Neovascularization Using Corticosteroid and Intravitreal Ranibizumab

Background To evaluate the treatment outcomes of patients with punctate inner choroidopathy (PIC) and secondary choroidal neovascularization (CNV). Methods This is a retrospective study of 24 eyes in 22 patients suffering from PIC with CNV. Patients were treated with intravitreal ranibizumab monotherapy (14 eyes) or combined oral corticosteroid and intravitreal ranibizumab therapy (corticosteroid-ranibizumab group, 10 eyes). Mean follow-up duration was 24.0 months. We evaluated best-corrected visual acuity (BCVA), fundus autofluorescence, fluorescein angiography, indocyanine green angiography, and optical coherence tomography, before and after treatment. The following variables were compared between groups: number of intravitreal ranibizumab injections, BCVA, recurrence of CNV, and change in PIC lesions. Results The ranibizumab monotherapy group received an average of 3 intravitreal ranibizumab injections; mean logMAR visual acuity improvement was 0.34, and 8 eyes developed recurrent CNV during follow-up. The corticosteroid-ranibizumab group received an average of 1.9 intravitreal ranibizumab injections; mean logMAR visual acuity improvement was 0.61, and there was no recurrence of CNV. Combined corticosteroid-ranibizumab therapy also resulted in better resolution of PIC lesions and fewer new PIC lesions. Conclusion Both corticosteroid-ranibizumab treatment and ranibizumab monotherapy could significantly improve the vision of PIC patients with CNV. Combined corticosteroid and intravitreal ranibizumab treatment appeared to reduce CNV recurrence and development of new PIC lesions compared with ranibizumab monotherapy.

Cases of visual impairment caused by cerebral venous sinus occlusion-induced intracranial hypertension in the absence of headache

BackgroundCerebral venous sinus thrombosis or stenosis (here collectively referred to as cerebral venous sinus occlusion, CVSO) can cause chronically-elevated intracranial pressure (ICP). Patients may have no neurological symptoms other than visual impairment, secondary to bilateral papilledema. Correctly recognizing these conditions, through proper ophthalmological examination and brain imaging, is very important to avoid delayed diagnosis and treatment.Case presentationWe report a case series of 3 patients with chronic CVSO, who were admitted to an ophthalmological department in Chongqing, China, from 2015 March to 2017 February. All patients presented with decreased vision and bilateral papilledema, but had no headache or other neurological symptoms. The visual fields of all patients were impaired. Flash visual evoked potentials (VEPs) in two patients showed essentially normal peak time of P2 wave, and pattern VEPs in one patient displayed decreased P100 amplitude in one eye, while a normal P100 wave in the other eye. In all patients, lumbar puncture (LP) revealed significantly elevated ICP. And magnetic resonance venography (MRV) demonstrated cerebral venous sinus abnormalities in every patient: one right sigmoid sinus thrombosis, one superior sagittal sinus thrombosis, and one right transverse sinus stenosis.ConclusionsCVSO can cause chronically-elevated ICP, leading to bilateral papilledema and visual impairment. A considerable amount of patients have no apparent neurological symptoms other than visual loss. Unlike other optic nerve lesions, such as neuritis or ischemic optic neuropathy, the optic disc edema in CVSO is usually bilateral, the flash or pattern VEP is often normal or only mildly affected, and patients are often not sensitive to steroid therapy. CVSO should be suspected in such patients when unenhanced brain imaging is normal. Further investigations, such as LP and contrast-enhanced imaging (MRV and digital subtraction angiography), should be performed to diagnose or exclude CVSO.