Abstract: Objective   To observe the effects of paeoniflorin on 3T3 fibroblast activation, proliferation and collagen production through IL-13/STAT6 signaling pathway.   Methods   3T3 cell strain was cultured with serum-free medium for 12 h, then stimulated by paeoniflorin （200, 400, 600, 800, and 1 000 mg/L） or rIL-13 （6.25, 12.5, 50, 100, and 200 μg/L） for another 24 h. At the same time the blank control group for paeoniflorin or rIL-13 was observed. 3T3 cell proliferation was assayed by Cell Counting Kit-8 （CCK-8）, and an appropriate concentration （100 μg/L） of rIL-13 was chosen according to the result of cell proliferation. Subsequently, 3T3 cell cultured with serum-free medium for 12 h was stimulated by 100 μg/L rIL-13 for 12 h, and then was treated with different concentrations of paeoniflorin （200, 400, 600, 800, and 1 000 mg/L） for another 24 h. Untreated 3T3 cell served as blank control. Cell proliferation was measured by CCK-8. Hydroxyproline content in cell supernatant was determined by alkaline lysis method. IL-13Rα1, α-SMA and STAT6 protein expression were detected by Western blotting. Col-Ⅰ, Col-Ⅲ, IL-13Rα1 and STAT6 mRNA expression were analyzed by RT-PCR.   Results   Pae-oniflorin inhibited 3T3 cell proliferation in a concentration-dependent manner （r=-0.980, P＜0.01）, and there was a statistically significant difference among all groups （F=198.599, P＜0.01）. rIL-13 caused a remarkably concentration-dependent increase in proliferation of 3T3 cells （r=0.538, P＜0.05）. Paeoniflorin （200, 400, 600, 800, and 1 000 mg/L） inhibited proliferation of 3T3 cell stimulated by rIL-13 in a concentration-dependent manner （1.780±0.177, 1.636±0.073, 0.965±0.066, 0.623±0.037, 0.337±0.022, r=-0.971, P＜0.01）, and among all groups there existed a significant difference （F=198.537, P<0.01）. Moreover, paeoni-florin also suppressed secretion of hydroxyproline from 3T3 cell stimulated by rIL-13 in a concentration-dependent manner （3.030±0.094, 2.976±0.047, 2.814±0.047, 2.652±0.124, 2.408±0.124, r=-0.916, P＜0.01） with a statistical significance among all groups （F=13.642, P＜0.01）. Further investigations showed that paeoniflorin decreased both protein expression of α-SMA, IL-13Rα1, and STAT6, and mRNA expression of Col-Ⅰ, Col-Ⅲ, IL-13Rα1, and STAT6 in 3T3 cell stimulated by rIL-13.  Conclusion   Paeoniflorin inhibits activation, proliferation of fibroblasts and production of collagen from fibroblasts through IL-13/STAT6 signaling pathway, which might be one of mechanisms of anti-hepatic fibrosis of paeoniflorin in schistosomiasis japonica.

Key words: Paeoniflorin；Fibroblast；Interleukin-13；Interleukin-13R&alpha, 1；CollagenⅠ；CollagenⅢ