Objective:To prepare the bacterial outer membrane vesicles(OMV)that can express programmed death ligand 1(PD-L1)nanobody on surface,and to discuss its structural characteristics,cell compatibility,intracellular distribution,and its blocking effect on the programmed cell death protein-1(PD-1)/PD-L1 signaling axis.Methods:The pET28a-ClyA-PD-L1nb prokaryotic expression vector was constructed and transformed into Escherichia coli BL21(DE3)competent cells;the OMV was isolated from the BL21(DE3)monoclonal colonies transformed with the PD-L1nb expression vector by ultracentrifugation;the protein purification was performed using the histidine(His)tag;transmission electron microscope and nanoparticle size analyzer were used to analyze and identify the OMV;the OMV isolated from the BL21(DE3)monoclonal colonies transformed with the PD-L1nb expression vector was used as experimental group;the OMV isolated from the untransformed BL21(DE3)monoclonal colonies was used as control group;Western blotting method was used to detect the expression levels of ClyA-PD-L1nb fusion protein in the OMV in two groups;cell counting kit-8(CCK-8)assay was used to detect the activities of mouse macrophage RAW 264.7 cells,mouse triple-negative breast cancer 4T1 cells,and human embryonic kidney HEK293T cells after treated with OMV;fluorescence imaging technology was used to observe the tumor cell endocytosis of OMV;flow cytometry was used to detect the binding effect of OMV to the PD-L1 on surface of the tumor cells in PBS group,OMV-PD-L1nb group,and aPD-L1+OMV-PD-L1nb group.Results:The sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)results showed that after induction of Escherichia coli,significantly thickened protein bands appeared near the predicted relative molecular mass(about 49 000),and after purification,no obvious impurity proteins existed in the lanes;the OMV-PD-L1nb with a size of about 120 nm was isolated by ultracentrifugation,and it presented a uniform spherical structure under transmission electron microscope;the Western blotting results showed that the specific band of ClyA-PD-L1nb was detected in the OMV in experimental group;the CCK-8 assay results showed that after treated with different concentrations of OMV,the viabilities of the RAW 264.7 cells,4T1 cells,and HEK293T cells were all close to 100％;the fluorescence imaging results showed that OMV-PD-L1nb was endocytosed by 4T1 cells and dispersed in the cytoplasm;compared with OMV-PD-L1nb group,the average fluorescence intensity in the cells in aPD-L1+OMV-PD-L1nb group was significantly decreased(P＜0.001).Conclusion:The OMV surface-displaying PD-L1nb,OMV-PD-L1nb,is successfully prepared and isolated;OMV-PD-L1nb shows good compatibility on mouse macrophage cells,tumor cells,and human embryonic kidney cells,can be endocytosed by tumor cells,and successfully blocks the PD-1/PD-L1 signaling pathway.

Objective:To discuss the anti-fatigue effect of Wujia Shengmai Yin,and to clarify its mechanism.Methods:Thirty-six male ICR mice were randomly devided into control group(equivalent volume of distilled water),Shengmai Yin group(500 mg·kg?1 of Shengmai Yin),and Wujia Shengmai Yin group(600 mg·kg?1 of Wujia Shengmai Yin).The body weights of the mice in various groups were detected every 7 d,and the mental states were observed.The rotating rod test and exhaustive swimming test were used to detect the duration on the rod and the swimming time to exhaustion of the mice in various groups,respectively;the levels of urea nitrogen(BUN)and lactate(LA),and the activities of lactate dehydrogenase(LDH)in serum,the levels of liver glycogen(LG),muscle glycogen(MG),and malondialdehyde(MDA),and activities of glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in muscle tissue of the mice in various groups were detected by kits;the expression levels of glucose metabolism-related proteins in liver tissue of the mice in various groups were detected by Western blotting method.Results:Compared with before experiment,the body weights after experiment of the mice in various groups showed a increasing trend but the differences were not statistically significant(P>0.05).The rotating rod test results showed that compared with control group,the duration on the rod of the mice in Wujia Shengmai Yin group was significantly increased(P<0.01).The exhaustive swimming test results showed that compared with control group,the swimming time to exhaustion of the mice in Shengmai Yin group and Wujia Shengmai Yin group was significantly increased(P<0.01).Compared with control group,the levels of BUN in serum of the mice in Shengmai Yin group and Wujia Shengmai Yin group were significantly decreased(P<0.01),and the activities of LDH were significantly increased(P<0.01);the level of LA of the mice in Wujia Shengmai Yin group was significantly decreased(P<0.01).Compared with Shengmai Yin group,the levels of BUN and LA in the serum and LDH activity of the mice in Wujia Shengmai Yin group were significantly decreased(P<0.01).Compared with control group,the levels of LG in liver tissue and the levels of MG in muscle tissue of the mice in Shengmai Yin group and Wujia Shengmai Yin group were significantly increased(P<0.01);compared with Shengmai Yin group,the level of LG in liver tissue and the level of MG in muscle tissue of the mice in Wujia Shengmai Yin group were increased(P<0.01).Compared with control group,the activities of GSH-Px and SOD in muscle tissue of the mice in Shengmai Yin group and Wujia Shengmai Yin group were significantly increased,and the levels of MDA in Shengmai Yin group and Wujia Shengmai Yin group was significantly decreased(P<0.01);compared with Shengmai Yin group,the activities of GSH-Px and SOD in muscle tissue of the mice in Wujia Shengmai Yin group were significantly increased and the level of MDA was decreased(P<0.01).The Western blotting results showed that compared with control group,the expression levels of phosphorylated phosphoinositide 3-kinase(p-PI3K),phosphorylated protein kinase B(p-AKT),phosphorylated glycogen synthase kinase 3 beta(p-GSK3β),and glycogen synthase(GS)proteins in liver tissue of the mice in Shengmai Yin group and Wujia Shengmai Yin group were significantly increased(P<0.05 or P<0.01);compared with Shengmai Yin group,the expression levels of p-PI3K,p-AKT,p-GSK3β,and GS proteins in liver tissue of the mice in Wujia Shengmai Yin group were significantly increased(P<0.01).Conclusion:Wujia Shengmai Yin enhances the anti-fatigue effect by activating the phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)/glycogen synthase kinase 3 beta(GSK3β)signaling pathways,and improves the body's antioxidant capacity,and increases the glycogen synthesis.