Baicalin affects the progression of diabetic retinopathy through the RAGE/PXDN/PI3K/AKT pathway

BACKGROUND: Diabetic retinopathy (DR) is the leading cause of blindness-related eye diseases in adults. The pathogenesis of DR is attributed to the excessive proliferation of microvessels, which leads to vitreous haemorrhage and retinal traction, thereby significantly damaging the patient's vision. In this study, we investigated the role and molecular mechanism of Peroxidasin (PXDN) and the active ingredient baicalin (BAI) of traditional Chinese medicine in regulating the senescence and pathological angiogenesis of human retinal microvascular endothelial cells (HRMECs) to identify the key genes and signalling pathways involved in the progression of DR. METHODS: In this study, key hub genes were screened using relevant datasets. The expression levels of PXDN, fibronectin (FN1), and PI3K/AKT pathway-related proteins were verified in clinical specimens, animal models, and DR cell models using enzyme-linked immunosorbent assays (ELISA), quantitative real-time PCR, Western blot, and immunohistochemistry (IHC). The binding ability of BAI to the receptor for advanced glycation end products (RAGE) was verified by molecular docking technology analysis and Western blot. Moreover, the direct binding relationship between PXDN and FN1 was verified by protein-protein interaction (PPI) and western blot. By further applying gene knockdown and overexpression techniques in combination with Western blot analysis, the molecular pathways through which BAI affects RAGE/PXDN(FN1)/PI3K/AKT signalling were investigated. RESULTS: In the DR model, the expression level of PXDN significantly increased. Direct protein interactions between PXDN and FN1 were verified through PPI and coimmunoprecipitation (Co-IP) experiments. Moreover, knockdown of PXDN in vivo and in vitro significantly reduced the formation of lesions. BAI inhibited the expression of PXDN and FN1 by binding to RAGE, thereby effectively alleviating the senescence and pathological angiogenesis of HRMECs induced by high glucose (HG) conditions through regulation of the PI3K/AKT signalling pathway. CONCLUSIONS: This study revealed that BAI regulates the progression of DR by regulating the RAGE/PXDN (FN1)/PI3K/AKT signalling pathway. These findings not only provide new molecular insights into the pathogenesis of DR but also lay an important theoretical foundation for the development of new therapeutic strategies.