Epigallocatechin-3-Gallate, an Active Green Tea Component to Support Anti-VEGFA Therapy in Wet Age-Related Macular Degeneration

Molecular mechanisms of Buqing granule for the treatment of diabetic retinopathy: Network pharmacology analysis and experimental validation

BACKGROUND

Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus. Its blindness rate is high; therefore, finding a reasonable and safe treatment plan to prevent and control DR is crucial. Currently, there are abundant and diverse research results on the treatment of DR by Chinese medicine Traditional Chinese medicine compounds are potentially advantageous for DR prevention and treatment because of its safe and effective therapeutic effects.

AIM

To investigate the effects of Buqing granule (BQKL) on DR and its mechanism from a systemic perspective and at the molecular level by combining network pharmacology and in vivo experiments.

METHODS

This study collected information on the drug targets of BQKL and the therapeutic targets of DR for intersecting target gene analysis and protein-protein interactions (PPI), identified various biological pathways related to DR treatment by BQKL through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses, and preliminarily validated the screened core targets by molecular docking. Furthermore, we constructed a diabetic rat model with a high-fat and high-sugar diet and intraperitoneal streptozotocin injection, and administered the appropriate drugs for 12 weeks after the model was successfully induced. Body mass and fasting blood glucose and lipid levels were measured, and pathological changes in retinal tissue were detected by hematoxylin and eosin staining. ELISA was used to detect the oxidative stress index expression in serum and retinal tissue, and immunohistochemistry, real-time quantitative reverse transcription PCR, and western blotting were used to verify the changes in the expression of core targets.

RESULTS

Six potential therapeutic targets of BQKL for DR treatment, including Caspase-3, c-Jun, TP53, AKT1, MAPK1, and MAPK3, were screened using PPI. Enrichment analysis indicated that the MAPK signaling pathway might be the core target pathway of BQKL in DR treatment. Molecular docking prediction indicated that BQKL stably bound to these core targets. In vivo experiments have shown that compared with those in the Control group, rats in the Model group had statistically significant (P < 0.05) severe retinal histopathological damage; elevated blood glucose, lipid, and malondialdehyde (MDA) levels; increased Caspase-3, c-Jun, and TP53 protein expression; and reduced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels, ganglion cell number, AKT1, MAPK1, and MAPK3 protein expression. Compared with the Model group, BQKL group had reduced histopathological retinal damage and the expression of blood glucose and lipids, MDA level, Caspase-3, c-Jun and TP53 proteins were reduced, while the expression of SOD, GSH-Px level, the number of ganglion cells, AKT1, MAPK1, and MAPK3 proteins were elevated. These differences were statistically significant (P < 0.05).

CONCLUSION

BQKL can delay DR onset and progression by attenuating oxidative stress and inflammatory responses and regulating Caspase-3, c-Jun, TP53, AKT1, MAPK1, and MAPK3 proteins in the MAPK signaling pathway mediates these alterations.

Vitamin D and Sulforaphane Decrease Inflammatory Oxidative Stress and Restore the Markers of Epithelial Integrity in an In Vitro Model of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is strictly linked to chronic oxidative stress, inflammation, loss of epithelial barrier integrity, and often with abnormal new blood vessel development. In this study, the retinal epithelial cell line ARPE-19 was treated with pro-inflammatory transforming growth factor-beta (TGF-β) to investigate the activity of vitamin D (VD) and sulforaphane (SF) in abating the consequences of oxidative stress and inflammation. The administration of VD and SF lowered reactive oxygen species (ROS) levels, and abated the related expression of the pro-inflammatory cytokines interleukin-6 and interleukin-8 induced by TGF-β. We evaluated mitochondrial respiration as a source of ROS production, and we discovered that the increased transcription of respiratory elements triggered by TGF-β was prevented by VD and SF. In this model of inflamed epithelium, the treatment with VD and SF also reduced the secretion of VEGF, a key angiogenic factor, and restored the markers of epithelial integrity. Remarkably, all the observed biological effects were potentiated by the co-stimulation with the two compounds and were not mediated by VD receptor expression but rather by the ERK 1/2 pathway. Altogether, the results of this study reveal the powerful synergistic anti-inflammatory activity of SF and VD and lay the foundation for future clinical assessment of their efficacy in AMD.

A New Generation of Gene Therapies as the Future of Wet AMD Treatment

Age-related macular degeneration (AMD) is an eye disease and the most common cause of vision loss in the Western World. In its advanced stage, AMD occurs in two clinically distinguished forms, dry and wet, but only wet AMD is treatable. However, the treatment based on repeated injections with vascular endothelial growth factor A (VEGFA) antagonists may at best stop the disease progression and prevent or delay vision loss but without an improvement of visual dysfunction. Moreover, it is a serious mental and financial burden for patients and may be linked with some complications. The recent first success of intravitreal gene therapy with ADVM-022, which transformed retinal cells to continuous production of aflibercept, a VEGF antagonist, after a single injection, has opened a revolutionary perspective in wet AMD treatment. Promising results obtained so far in other ongoing clinical trials support this perspective. In this narrative/hypothesis review, we present basic information on wet AMD pathogenesis and treatment, the concept of gene therapy in retinal diseases, update evidence on completed and ongoing clinical trials with gene therapy for wet AMD, and perspectives on the progress to the clinic of "one and done" therapy for wet AMD to replace a lifetime of injections. Gene editing targeting the VEGFA gene is also presented as another gene therapy strategy to improve wet AMD management.