Study On The Therapeutic Effect And Mechanism Of Spermidine In Collagen-induced Arthritis Mice

Objection:To explore the therapeutic effect and mechanism of spermidine(SPD)on mice with collagen induced arthritis(CIA),and to provide new ideas for the treatment of rheumatoid arthritis.Methods:25 male 6-week-old C57BL/6 mice,5 of them were randomly selected as normal control group,and the others were used for CIA model establishment.On the 27 th day after the first immunization,the mice successfully modeled were randomly divided into four groups:CIA control group,SPD-H group,SPD-M group and SPD-L group,with 5mice in each group.Saline,50 mg/kg SPD,10 mg/kg SPD,and 2 mg/kg SPD were given into the mice everyday by intraperitoneal injection respectively for 21 days.The thickness of the left foot pad of the mice was regularly measured and arthritis scores were performed.On the 49 th day,the degree of paw swelling before and after treatment was calculated,and blood and ankle joint samples were collected from mice in each group The enzyme-linked immunosorbent assay method was used to detect the contents of interleukin-6(IL-6),tumor necrosis factor-?(TNF-?)and IL-10 in serum of mice.Hematoxylin-eosin staining(HE)and immunohistochemical staining were respectively applied to observed the synovial pathology score and the expression of F4/80,inducible nitric oxide synthase(iNOS)and CD206 in synovial tissue of the ankle joint.Results:1.Paw thickness and arthritis scores of CIA mice treated with different concentrations of spermidine showed a downward trend,and the SPD-H group had the most obvious decline2.Three concentrations of spermidine all can alleviate the degree of paw swelling in mice.The SPD-H group's arthritis score decreased first.The degree of paw swelling in the SPD-L group is significantly less than that in the CIA control group(P<0.05)3.Serum IL-6 levels in the CIA control group were significantly higher than those in the SPD-H,SPD-L and normal control groups(P<0.05),and TNF-? levels were significantly higher than those in the SPD-H group,SPD-M group,SPD-L group and normal control group(P<0.01),while the IL-10 levels in the CIA control group were significantly lower than those of SPD-H group,SPD-L group and normal control group(P <0.05)4.Compared with the normal control group,the CIA control group had significant synovial cell proliferation,lymphocyte infiltration,and fibrinoid necrosis(P<0.01).The SPD-H group had significantly lower lymphocyte infiltration than the CIA control group(P<0.05).The fibrinoid necrosis scores of different density of spermidine-treated groups were lower than those of the CIA control group(P<0.05)5.Spermidine inhibits iNOS expression in synovial macrophages of ankle joint in CIA mice in a dose-dependent manner.Conclusions:1.Spermidine can effectively improve joint swelling and reduce arthritis score in CIA mice.And the 50mg/kg spermidine has better therapeutic effect2.Spermidine can significantly reduce synovial cell proliferation,inflammatory cell infiltration,and fibroid necrosis in CIA mice,and has a good anti-inflammatory effect3.Spermidine can reduce the levels of IL-6 and TNF-? and increase the level of IL-10 in the serum of CIA mice.SPD can inhibit the polarization of M1 macrophages in synovial tissue,suggesting that the anti-inflammatory effect of spermidine may be related to the macrophage polarization.