ObjectiveTo investigate whether co-activated mesenchymal stem cells（MSCs） exert therapeutic effects against schistosomiasis by modulating macrophage polarization. MethodsTwenty adult male Balb/c mice were randomly divided into four groups： uninfected， infected， MSC-treated， and MSC^TLR4+IFN-γ-treated groups. The Schistosoma japonicum infection model was established via abdominal patch method with cercariae. At week 5 post-infection， praziquantel was administered orally for antiparasitic treatment. At week 6， mice received either MSCs treatments （with or without pre-activation） or no treatment. Body weight changes were monitored weekly. Hepatic pathological alterations were evaluated via HE and Masson staining. RT-qPCR was used to assess α-SMA and collagen （Col-I， Col-Ⅲ） mRNA levels to quantify fibrosis. The mRNA levels of hepatic inflammatory cytokines and matrix metalloproteinases（MMP） were analyzed to explore fibrotic mechanisms. The expressions of i-Nos and Arg-1 in liver tissues were detected by RT-qPCR， and the ratio of M1 or M2 macrophages was detected by immunofluorescence staining， aiming to analyze the correlation between MSCs treatment and macrophage polarization. An in vitro co-culture system validated direct MSC-macrophage interactions. ResultsCompared with the infected group， the MSC^TLR4+IFN-γ group exhibited increased body weight gain （P< 0.01）， reduced hepatic granulomatous lesion area （P< 0.001）， and decreased α-SMA， Col-I， and Col-Ⅲ mRNA levels （P< 0.01）. Additionally， the MSC^TLR4+IFN-γ group showed reduced TNF-α and IL-1β expression （P< 0.05）， as well as elevated MMP2， Mmp9， and MMP13 levels （P< 0.01）. The MSC^TLR4+IFN-γ group showed higher expression of M2 marker Arg-1 mRNA compared with the infection group （P < 0.001） ， while the expression of M1 marker i-Nos decreased （P< 0.05）. Immunofluorescence confirmed a lower i-Nos+ cell ratio （P< 0.05） and higher F4/80⁺CD206⁺ cell ratio （P< 0.000 1） in the MSC^TLR4+IFN-γ group compared with the infection group. In vitro co-culture experiments further demonstrated that MSC^TLR4+IFN-γ promoted Arg-1 expression， suppressed pro-inflammatory cytokine i-Nos and TNF-α levels， consistent with ELISA results. ConclusionsThis study reveals that TLR4 and IFN-γ co-activated MSCs alleviate Schistosoma japonicum-induced hepatic fibrosis， potentially through modulating macrophage polarization toward the M2 phenotype. This mechanism may suppress inflammation and enhance extracellular matrix degradation， providing a therapeutic strategy for schistosomiasis-associated liver fibrosis.