Elucidating the mechanism by which Aloe-emodin from Cassiae semen treats diabetic retinopathy via network pharmacology and experimental verification

The aim of this study was to investigate the possible mechanism by which Cassiae Semen treats DR via network pharmacology and to validate this mechanism via in vitro experiments. The active ingredients and potential DR-related targets of Cassia Semen were screened using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) platform and other disease-related databases. A protein‒protein interaction network for these common targets was subsequently established via the STRING database. Key active ingredients and core targets were selected through network topology analysis using Cytoscape software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted using the DAVID database. In vitro experiments were designed to further validate the key active components and targets of Cassiae Semen identified by network pharmacology analysis. Twenty-one common targets were selected. Aloe-emodin (AE) was speculated to be the main active ingredient of Cassiae Semen in the treatment of DR. Cassiae Semen might act through various biological processes, including by regulating apoptosis, oxidative stress, and inflammation. In vitro, AE effectively inhibited lipopolysaccharide (LPS)-induced BV2 cell proliferation and downregulated the mRNA expression of M1 microglia-related genes (COX2, iNOS, TNF-α, IL-1β and IL-6). Furthermore, AE inhibited proinflammatory cytokine (TNF-α, IL-1β and IL-6) secretion and the expression of the inflammatory protein COX2 in LPS-stimulated BV2 cells. Network pharmacology and in vitro experiments revealed that AE, the key active component of Cassiae Semen, suppresses inflammation by inhibiting M1 microglial polarization, making it a potential therapeutic agent for DR.