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.