IFN-γ And TLR4 Activated Mesenchymal Stem Cells Influence Liver Fibrosis In Schistosomiasis By Regulating Macrophage Polarization

Objective: Bone marrow mesenchymal stem cells(MSC)have been tried in the treatment of liver fibrosis,and there is no effective method for the treatment of liver fibrosis caused by advanced schistosomiasis,so mesenchymal stem cells(MSC)have also been tried in the treatment of liver fibrosis caused by schistosomiasis.Previous studies have preliminarily found that IFN-γ and TLR4 co-activated MSC can alleviate liver fibrosis in schistosomiasis,but the mechanism remains to be clarified.The polarization regulation of macrophages is the central link in the direction of liver fibrosis.In this study,the effects of IFN-γ and TLR4 co-activated MSC on liver fibrosis and macrophage polarization in schistosomiasis were further investigated.Methods: Balb /c mice were infected with 15±2 cercariae through the skin at 8 weeks after abdominal shaving.Normal saline or MSC cells or IFN-γ and TLR4 co-activated MSC cells were injected through the tail vein at 1 and 3 weeks after infection,and samples were collected at 8 weeks after infection.HE staining of liver sections and immunofluorescence staining of frozen sections were compared.The indicators of fibrosis and macrophage polarization were detected by real-time fluorescence quantitative PCR,and the expression of macrophage polarization related proteins was detected by Western blot.The effects of mesenchymal stem cells on the polarization of macrophages from bone marrow cells from Schistosomia-infected mice and RAW264.7 were examined in vitro.Results: It was found that IFN-γ and TLR4 co-activated MSC can reduce the area of schistosomiasis liver fibrosis,reduce the expression of α-SMA,Col-Ⅰ and other fibrosis genes,can promote the liver i NOS expression decreased,Arg-1 expression increased,F4/80+CD206+ M2 macrophages increased.However,F4/80+i NOS+ reduced M1 type macrophages.In vitro experiments showed that IFN-γ and TLR4 co-activated MSCs could down-regulate i NOS and TNF-α genes and up-regulate Arg-1 genes in bone marrow macrophages of Schistosomia-infected mice.TNF-α protein level was down-regulated and IL-10 protein was up-regulated.IFN-γ and TLR4 co-activated MSC could up-regulate ARG-1,MRC-1,IL-10 and other genes in RAW264.7 cells,but did not inhibit i NOS,IL-1β,TNF-αgenes.Conclusion: IFN-γ and TLR4 co-activated MSC can reduce the liver fibrosis caused by schistosomiasis,but not induced MSC has no obvious therapeutic effect.Co-activation of MSC may promote the polarization of M2 macrophages by inhibiting M1,reduce the inflammatory response in the acute phase or promote matrix remodeling.This study provides a new basis for MSC in the treatment of liver fibrosis in schistosomiasis.