The Role And Mechanism Of Stromal Cell-derived Factor-1 In Endometrial Regenerative Cells Mediated Inhibition Of Sepsis In Mice

BackgroundSepsis refers to a systemic inflammatory response syndrome caused by infectious factors,which has a dangerous condition and a high mortality.Endometrial regenerative cells(ERCs)are derived from menstrual blood,and their phenotype is similar to mesenchymal stromal cells(MSCs),but they have many advantages.The treatment of human ERCs has been proven effective in various animal disease models and has been clinically applied.Stromal cell-derived factor-1(SDF-1),also known as CXCL12,its specific binding receptor is CXCR4,which is expressed on the surface of ERCs,and its specific blocker is AMD3100.The SDF-1/CXCR4 pathway mediates cell adhesion,chemotaxis and proliferation,and is highly conserved among different species.It is worth noting that SDF-1 can affect the expression of CXCR4 on the surface of ERCs,and ERCs themselves can secrete a large amount of SDF-1.We speculate that ERCs with high expression of CXCR4 can reach the injury site under the chemotactic effect of SDF-1,and can secrete SDF-1 to recruit more ERCs to regulate immune imbalance and reduce tissue damage.Taken together,this study aimed to explore the role and corresponding mechanism of SDF-1 in mediating ERCs in suppressing mouse sepsis.Objective 1.To clarify the effect of SDF-1 on the expression level of CXCR4 on the surface of ERCs;2.To clarify the effect of SDF-1-pretreated ERCs on the expression levels of CXCR4 and SDF-1 in mouse tissues;3.To explore the role of SDF-1 in mediating ERCs in suppressing mouse sepsis.Methods 1.In in vitro experiments,human ERCs were co-cultured with two concentrations of SDF-1 solutions(0 ng/ml,50 ng/ml)for 72 hours,and the percentage of CXCR4-positive ERCs was analyzed by flow cytometry.2.In in vivo experiments,the expression levels of CXCR4 and SDF-1 in the liver and lungs of sepsis mice treated with SDF-1-pretreated ERCs were detected.3.C57B/L6 mice were injected intraperitoneally with a 10 mg/kg lipopolysaccharide solution to establish a sepsis model.The groups were:(1)normal control group,(2)untreated group,(3)unmodified ERCs treatment group,(4)AMD3100-pretreated ERCs treatment group,and(5)SDF-1-pretreated ERCs treatment group.Symptoms related to sepsis,rectal temperature,and survival were recorded in mice.Mice were euthanized after 24 hours,and then serum,liver and lungs were collected.The expression levels of apoptosis and proliferation-related cytokines(Bax,Bcl-2,PCNA),inflammatory cytokines(TNF-α,IL-1β,IL-4,IL-10,NF-κB)and oxidative stress related factors(i NOS,MDA,Nrf2,SOD,HO-1)were detected.Results 1.In vitro experiments showed that the expression level of CXCR4 on the surface of ERCs co-cultured with 50 ng/ml SDF-1 was significantly higher than that on the surface of ERCs co-cultured with 0 ng/ml SDF-1.2.In vivo experiments showed that the expression levels of CXCR4 and SDF-1 m RNA in liver and lung tissues of SDF-1-pretreated ERCs treatment group were higher than those of unmodified ERCs treatment group and unmodified ERCs treatment group is higher than AMD3100-pretreated ERCs treatment group.3.Compared with the unmodified ERCs treatment group,the sepsis-related symptoms were significantly ameliorated,and the pathological damage of liver and lung was significantly reduced.In terms of apoptosis,Bax m RNA levels decreased significantly,while Bcl-2 m RNA levels,Bcl-2/Bax m RNA ratio and PCNA protein levels increased significantly.In terms of inflammation,the levels of TNF-α and IL-1β decreased significantly,while the levels of IL-4 and IL-10 increased significantly.In terms of oxidative stress,i NOS m RNA levels and MDA concentrations were significantly reduced,and SOD,HO-1 and Nrf2 m RNA levels were significantly increased.The above-mentioned performance of the AMD3100-pretreated ERCs treatment group was worse than that of the unmodified ERCs treatment group.Conclusions 1.The SDF-1 pretreatment significantly increased the expression level of CXCR4 on the surface of ERCs,which is the key to the therapeutic effect improvement of SDF-1-pretreated ERCs.2.SDF-1-pretreated ERCs significantly increased SDF-1 and CXCR4 levels in liver and lung tissues.3.SDF-1-pretreated ERCs further improved the sepsis symptoms in mice.4.SDF-1-pretreated ERCs further ameliorated pathological changes in liver and lung tissues.5.SDF-1-pretreated ERCs further enhanced the anti-apoptotic and proliferative capacity of liver cells.6.SDF-1-pretreated ERCs further enhanced immune regulation in sepsis.7.SDF-1-pretreated ERCs further enhanced the anti-oxidative stress in sepsis.