RESUMO
Objective:To investigate the mechanism of human placenta derived mesenchymal stem cells (hPMSCs) in the inhibition of TNF-α secretion in CD4 + IFN-γ + T cells (Th1) through CD73/nuclear factor-erythroid 2-related factor 2(Nrf2) pathway to reduce liver injury in mice with graft versus-host disease (GVHD). Methods:Flow cytometry (FCM) was used to analyze the expression of TNF-α in Th1 cells and the expression of PD-1 on CD4 + IFN-γ + TNF-α + T cells (TNF-α + Th1 cells) isolated from peripheral blood and liver tissues of mice with GVHD. Hematoxylin-hosin (HE) staining, Masson staining and immunofluorescence staining were used to observe the pathological changes in liver tissues of GVHD mice in each group. HE staining was also used to observe the pathological changes in skin and lung tissues of GVHD mice. A nonconditional protocol to induce the differentiation of peripheral blood mononuclear cells (PBMCs) into Th1 cells in vitro was established. The proportion of TNF-α + Th1 cells and the mean fluorescence intensity (MFI) of Nrf2 and phosphorylated nuclear factor-kappa B (p-NF-κB) in this T cell subgroup were detected. Results:Compared with the normal control group, the proportion of TNF-α + Th1 cells and the expression of PD-1 on this T cells in peripheral blood and liver tissues of mice in the GVHD high group increased significantly ( P<0.01). The proportion of TNF-α + Th1 cells in peripheral blood and liver tissues decreased after hPMSCs treatment ( P<0.001), but the expression of PD-1 on this T cell subset was promoted in peripheral blood and liver tissues ( P<0.01, P<0.001). However, the intervention effects of shCD73 on TNF-α + Th1 cells in peripheral blood and liver tissues were significantly weakened ( P<0.05, P<0.01). Liver histopathological analysis showed that the proportion of TNF-α + Th1 cells in liver was positively correlated with Suzuki′s score, collagen area and the MFI of α-SMA ( P<0.001). Similarly, histopathological analysis of skin and lung tissues also showed that the proportion of TNF-α + Th1 cells in peripheral blood was positively correlated with skin Marina score and lung Shukai Qiao score ( P<0.001). In vitro experiment also showed that hPMSCs down-regulated the proportion of TNF-α + Th1 cells ( P<0.01) and up-regulated the expression of PD-1 on them ( P<0.05). Further analysis showed that hPMSCs could enhance the MFI of Nrf2 ( P<0.05) and weaken the MFI of p-NF-κB ( P<0.01) in TNF-α + Th1 cells. Conclusions:hPMSCs could up-regulate the expression of PD-1 through CD73/Nrf2 pathway to inhibit the formation of TNF-α + Th1 cells, thereby alleviating liver injury in GVHD mice.
RESUMO
Objective:To investigate the mechanism of IL-6 affecting the expression of CD73 on human placenta-derived mesenchymal stem cells (hPMSCs) and regulating their migration, adhesion and proliferation.Methods:Flow cytometry (FCM) and Western blot were used to analyze the effects of exogenous IL-6 or IL-6 secreted by hPMSCs on the expression of CD73 on hPMSCs. The influence of IL-6 on the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) in hPMSCs was detected by monoclonal antibody blocking test and Western blot. Real-time cellular analysis (RTCA) was used to analyze the changes in the migration, adhesion and proliferation of hPMSCs after knockdown of CD73 expression or APCP pretreatment.Results:FCM and Western blot showed that both exogenous and autocrine IL-6 from hPMSCs promoted the expression of CD73 on hPMSCs ( P<0.001, P<0.01). Moreover, CD73 expression decreased significantly with the presence of IL-6R inhibitor ( P<0.01). IL-6 could up-regulate the levels of both p-STAT3 and CD73 in hPMSCs ( P<0.05, P<0.01), while CD73 expression decreased after adding STAT3 inhibitor ( P<0.01). RTCA showed that knockdown of CD73 expression on hPMSCs significantly inhibited the adhesion and proliferation ability of hPMSCs( P<0.01, P<0.05), but promoted the migration ability of hPMSCs ( P<0.05). Similarly, inhibiting the hydrolase activity of CD73 on hPMSCs by APCP also resulted in a significant decrease in the adhesion and proliferation capacities of hPMSCs, and an increase in the migration capacity of hPMSCs ( P<0.05). Conclusions:IL-6 enhanced the expression of CD73 on hPMSCs via the JAK/STAT3 pathway, thus affecting the migration, adhesion and proliferation of hPMSCs.