| OBJECTIVE: Tubular interstitial fibrosis is believed to be the common final pathway to end-stage renal failure. Recently, it has been found that renal tubular epithelial cells-myofibroblast transdifferentiation (TEMT) and tubular epithelial cell apoptosis play an important role in the progress of renal interstitial fibrosis. alpha-smooth muscle actin(a-SMA) protein is the hallmark of myofibroblast. It has been proved that transforming growth factor-β1 (TGF-β1) induced tubular epithelial-myofibroblasts differentiation, and the downstream effectors was connective tissue growth factor (CTGF); TGF-β1 can also lead to apoptosis of renal tubular epithelial cells, resulting in tubular atrophy. Many researches show that panax notoginseng can delay the progress of renal interstitial fibrosis, and improve the structure and function of kidney. As the main component of panax notoginseng, Does panaxoside Rg1 also retard the progress of renal interstitial fibrosis? The objective of our research was to observe the effects of panaxoside Rg1 on TEMT and proliferation in NRK52E induced by TGF-β1, and the expression of CTGF and ECM in TEMT.METHODS: Cultured normal rat kidney tubular epithelial cells (NRK-52E) were divided into control group, TGF-β1-induced group and different dose and time of panaxoside Rg1. When cells were adherent, panaxoside Rg1 were added, which indicated a final concentration of 10, 20, 40mg/ml. Meanwhile, TGF-β1 was also added, which indicated a final concentration of 5ng/ml. Those confluent cells were incubated for 5 days. The morphology of tubular Epithelial-myofibroblast transdifferentiation induced by TGF-β1 was observed through light microscope. a-SMA and CTGF protein and gene expression were assessed by immunohistochemistry and Real-time quantitative chain reaction. The collagenⅠ, collagenⅢand fibronectin was measured by ELISA. MTT was used to measure cell proliferation.RESULTS: (1) After 5d exposured to 5ng/ml TGF-β1, we observed that many cells showed fibroblast-like in morphology under light microscope. Compared to control group, TGF-β1 could significantly up-regulate a-SMA and CTGF protein and gene expression by immunohistochemistry and real-time polymerase chain reaction of NRK52E (P＜0.05). The collagenⅠ, collagenⅢand fibronectin were significantly increased (P＜0.05). MTT showed that cell proliferation was inhibited (P＜0.05). (2) Compared to TGF-β1-induced group, panaxoside Rgl could inhibit the change in morphology and significantly down-regulate a-smooth muscle actin and CTGF protein and gene expression by immunohistochemistry and RT-PCR (P＜0.05). The collagenⅠ,collagenⅢand fibronectin of supernatant was significantly reduced(P＜0.05). MTT showed that panaxoside Rg1 Promote cell proliferation (P＜0.05). (3) Col-Ⅲsecretion and the a-SMA mRNA, CTGFmRNA expression was positively correlated. The correlation coefficient was respectively 0.818, 0.863, P＜0.05. Cell proliferation and the a-SMA mRNA, CTGF mRNA expression were negativly correlated, which was respectively-0.899,-0.907, P＜0.05. Cell proliferation and Col-Ⅰ, FN secretion was negativly correlated, which was respectively-0.967,-0.987, P＜0.05.CONCLUSIONS:(1) Besides inhibited cell proliferation, TGF-β1 could induce tubular Epithelial-myofibroblast transdifferentiation and increase collagenⅠ, collagenⅢand fibronectin in NRK52E. (2) Panaxoside Rg1 could prevent TGF-β1 inducing TEMT, decrease collagenⅠ, collagenⅢand fibronectin and promote cell proliferation. (3) Panaxoside Rgl could prevent TGF-β1 inducing TEMT, decreased collagenⅠ,collagenⅢand fibronectin, which were caused by inhibiting the expression of CTGF. (4) Panaxoside Rgl promoted cell proliferation in NRK52E. This was relevanted with inhibiting TEMT, expression of CTGF and secret of ECM.
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