Effect of metformin on bleomycin-induced systemic sclerosis mice by regulating the balance of Teff/regulatory T cells / 中华风湿病学杂志

ABSTRACT

Objective:To explore the effect and mechanism of different concentrations of metformin on bleomycin (BLM)-induced systemic sclerosis (SSc) mice model.Methods:C57BL/6 mice were divided into the normal group, the model group, the high, the medium and the low metformin (MET) treatment groups randomly. All mice were sacrificed after BLM and metformin treatment for 4 weeks. Local skin was exminedby histopathological staining method to measure the thickness of dermis and collagen, and immunohistochemistry and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) were used to detect the protein and mRNA levels of Interleukin (IL)-17, forkhead box P3 (Foxp3) and α-smooth muscle actin (α-SMA). Flow cytometry was used to detect the percentage of effector T cell (Teff) and regulatory cells (Treg) in splenic mononuclear cells. The data such as dermal collagen thickness, α-SMA, IL-17, Foxp3, Teff and Treg levels were statistically analyzed by one-way analysis of variance. The data such as dermal collagen thickness, α-SMA, IL-17, Foxp3, Teff and Treg levels were analyzed by one-way analysis of variance, and least significant difference (LSD)- t or Kruskal-Wallis test was used for comparison between groups. Results:Compared with the normal group, remarkable fibrotic lesions appeared in the skin of mice in the model group, and the levels of T-helper cells (Th)1, Th2, Th17, and T follicular helper cells (Tfh) cells were increased, accompanied by a significant decrease in the level of Treg cells. After high-dose metformin treatment, the dermal thickness [(131±25) μm], collagen thickness [(119±18) μm], and α-SMA [(3.0±0.5)/HPH] were significantly reduced( F=14.390, P<0.01; F=40.245, P<0.01; F=44.626, P<0.01). Th1[(27.00±6.68)%], Th17[(0.56±0.20)%], Tfh[(6.4±1.6)%] cells ware significantlyreduced ( F=32.390, P<0.01; F=16.083, P<0.01; F=16.546, P<0.01), and Treg[(11.23±1.52)%] cells were significantly increased ( F=10.171, P<0.01). Conclusion:Metformin can effectively reverse the local skin changesin BLM-induced SSc mouse model, and show immune regulation and anti-fibrosis effects by restoring the Teff/Treg balance.