Effects of saponin from the seed of Litchi chinensis Sonn on TGF-β1, FN and SOCS-1 in renal tubular epithelial cells under high glucose

Objective: To investigate the effect of saponin from the seed of Litchi chinensis Sonn (SLS) on the growth and apoptosis of human kidney epithelial cells (HKC) cultured in high glucose. Methods: HKC were cultured in DMEM/F12 medium supplemented with 30 mmol/L glucose and treated with or without SLS. In the normal group, isometric DMEM/F12 medium with 5.5mmol/L glucose was added. The secretion of TGF-β1 and fibronectin (FN) were detected by ELISA. Cell apoptosis was detected by the method of Annexin V-FITC/PI double staining. Western blot was used to detect the level of suppressor of cytokine signaling-1 (SOCS-1). Results: The result of ELISA showed that the secretion of TGF-β1 and FN was decreased in SLS groups compared with those in 30 mmol/L glucose treated group (P 0.05). There were more cells apoptosis in 30 mmol/L glucose treated group than that in the normal group (P 0.01). Compared with the 30 mmol/L glucose treated group, the apoptosis of HKC were significantly decreased in SLS groups (P 0.01). Western blot showed that the level of SOCS-1 in high glucose + SLS group was decreased (P 0.01), compared with the high glucose group. Conclusion: SLS can reduce the secretion of TGF-β1 and FN in HKC by reducing the deposition of extracellular matrix. SLS also significantly reduced the apoptosis of HKC by inhibiting the level of SOCS-1. These results suggest the roles of SLS in preventing the progress of glomerular sclerosis.