Establishing a mouse model of choroidal neovascularization to study the therapeutic effect of levotinib and its mechanism

Prevention of Inflammation, Neovascularization, and Retinal Dysfunction by Kinin B1 Receptor Antagonism in a Mouse Model of Age-Related Macular Degeneration

The kallikrein-kinin system (KKS) contributes to vascular inflammation and neovascularization in age-related macular degeneration (AMD), particularly via the kinin B1 receptor (B1R). The aim of the present study was to determine the protective effects of the topical administration of the B1R antagonist (R-954) on inflammation, neovascularization, and retinal dysfunction in a murine model of neovascular AMD. Choroidal neovascularization (CNV) was induced in C57BL6 mice using an argon laser. A treatment with ocular drops of R-954 (100 μg/15 μL, twice daily in both eyes), or vehicle, was started immediately on day 0, for 7, 14, or 21 days. CNV, invasive microglia, and B1R immunoreactive glial cells, as well as electroretinography alterations, were observed within the retina and choroid of the CNV group but not in the control group. The staining of B1R was abolished by R-954 treatment as well as the proliferation of microglia. R-954 treatment prevented the CNV development (volume: 20 ± 2 vs. 152 ± 5 × 104 µm3 in R-954 vs. saline treatment). R-954 also significantly decreased photoreceptor and bipolar cell dysfunction (a-wave amplitude: -47 ± 20 vs. -34 ± 14 µV and b-wave amplitude: 101 ± 27 vs. 64 ± 17 µV in R-954 vs. saline treatment, day 7) as well as angiogenesis tufts in the retina. These results suggest that self-administration of R-954 by eye-drop treatment could be a promising therapy in AMD to preserve retinal health and vision.

Dietary astaxanthin-rich extract ameliorates atherosclerosis/retinopathy and restructures gut microbiome in apolipoprotein E-deficient mice fed on a high-fat diet

Scope: Atherosclerosis (AS) is the leading cause of ischemic disease. However, the anti-AS effects of astaxanthin and its potential mechanisms remain unclear. This study is aimed to investigate the function of astaxanthin-rich extract (ASTE) on AS and gut microbiota as well as the difference from atorvastatin (ATO) in apolipoprotein E-deficient (ApoE^-/-) mice. Methods and results: Wild type (WT) and ApoE^-/- mice were divided into seven groups: the low-fat diet (LFD) and high-fat diet (HFD) groups (in both types) as well as three ApoE^-/- groups based on HFD added with two doses of ASTE and one dose of ATO, respectively. After 30 weeks of intervention, results showed that ASTE significantly inhibited body weight increase, lipids accumulation in serum/liver, and AS-lesions in the aorta. Furthermore, fundus fluorescein angiography and retinal CD31 immunohistochemical staining showed that ASTE could alleviate the occurrence of AS-retinopathy. H&E staining showed that ASTE could protect the colon's mucosal epithelium from damage. The gas chromatographic and gene expression analyses showed that ASTE promoted the excretion of fecal acidic and neutral sterols from cholesterol by increasing LXRα, CYP7A1, and ABCG5/8 and decreasing FXR, NPC1L1, ACAT2, and MTTP expressions. Remarkably, the ASTE administration maintained the gut barrier by enhancing gene expression of JAM-A, Occludin, and mucin2 in the colon and reshaped gut microbiota with the feature of blooming Akkermansia. Conclusion: Our results suggested that ASTE could prevent AS in both macrovascular and/or microvascular as well as used as novel prebiotics by supporting the bile acid excretion and growth of Akkermansia.

The Antiangiogenic Effect of Sanguinarine Chloride on Experimental Choroidal Neovacularization in Mice via Inhibiting Vascular Endothelial Growth Factor

Background: The purpose of this study is to investigate the antiangiogenic effect of Sanguinarine chloride (SC) on models of age-related macular degeneration (AMD) both in vivo and in vitro.

Methods: Choroidal neovascularization (CNV) was conducted by laser photocoagulation in C57BL6/J mice. SC (2.5 μM, 2 μl/eye) was intravitreally injected immediately after laser injury. The control group received an equal amount of PBS. 7 days after laser injury, CNV severity was evaluated using fundus fluorescein angiography, hematoxylin and eosin (H&E) staining, and choroid flat-mount staining. Vascular endothelial growth factor (VEGF) expression in the retina/choroid complex was measured by western blot analysis and ELISA kit. In vitro, human retinal microvascular endothelial cells (HRMECs) were used to investigate the effects of SC on cell tube formation, migration, and cytotoxicity. The expression of VEGF-induced expression of extracellular signal-regulated kinase (ERK)1/2, protein kinase B (AKT), mitogen-activated protein kinases (p38-MAPK) in vitro and laser induced VEGF expression in vivo were also analyzed.

Results: SC (≤2.5 μM) was safe both in vitro and in vivo. Intravitreal injection of SC restrained the formation of laser induced CNV in mice and decreased VEGF expression in the laser site of the retina/choroid complex. In vitro, SC inhibited VEGF-induced tube formation and endothelial cell migration by decreasing the phosphorylation of AKT, ERK1/2, and p38-MAPK in HRMECs.

Conclusions: SC could inhibit laser-induced CNV formation via down-regulating VEGF expression and restrain the VEGF-induced tube formation and endothelial migration. Therefore, SC could be a potential candidate for the treatment of wet AMD.