BHTCM Protects Muller Cells from Diabetic Retinopathy by Reducing Abnormal Changes of Kir4.1 and AQP4, Suppressing VEGF and IL-1, and Enhancing PEDF Production

Background In the diabetic condition, damage to the Muller cells contributes to the pathogenesis of diabetic retinopathy. Aims This study aimed to investigate the protective effect of Bushen Huoxue, Traditional Chinese Medicine (BHTCM), on Muller in diabetic retinopathological conditions. Methods Primary rat retinal Muller cells (RRMC) were isolated and cultured under high glucose (50 nmol/L). The advanced glycation end products (AGEs) and sodium dithionite were applied to treat high-glucose administrated RRMC to mimic diabetic retinopathological conditions. The effects of BHTCM on diabetic retinopathological RRMC were evaluated. The expressions of aquaporin-4 (AQP4) and Kir4.1 were determined by double-labeling immunofluorescence and ELISA. Levels of vascular endothelial growth factor (VEGF), interleukin-1 & beta; (IL-1 & beta;) and pigment epithelium-derived factor (PEDF) were examined with ELISA. Lactate dehydrogenase (LDH) activity was also evaluated. Results Retinal Muller cells were successfully isolated and identified. RRMC treated with AGEs and sodium dithionite resulted in the increase of AQP4 and decrease of Kir4.1 in RRMC, increase of VEGF and IL-1 & beta; secretion, increase of LDH activity, decrease of PEDF secretion in culture medium, all of which, in a dose-dependent or time-dependent manner. Post treating RRMC with AGEs and dithionite, BHTCM reversed changes in expression of AQP4 and Kir4.1 in RRMC, and reversed VEGF levels, PEDF and IL-1 & beta; secretion in the culture medium. Moreover, BHTCM reversed the decrease of RRMC cell membrane integrity after AGEs and dithionite treatment. Conclusion BHTCM protected Muller cells from diabetic damage by reducing abnormal changes of Kir4.1 and AQP4, inhibiting VEGF and IL-1 & beta;, increasing PEDF production, and maintaining cell membrane integrity. Therefore, BHTCM is a potential drug for the treatment of diabetic retinopathy, which can correct the function of Muller cells.