The Role And Molecular Mechanism Of IFN-?-induced Mesenchymal Stem Cell Metabolism Reprogrammingin Its Immunoregulatory Phenotype Transformation

BackgroundMesenchymal stem cells(MSCs)are pluripotent stem cells,which in addition to being able to differentiate into adipocytes,bone cells,and chondrocytes,also have some immunoregulatory functions.The various signal-stimulating molecules during the inflammatory response are essential for the ability of MSCs to exert immunomodulatory effects and determine the fate of immune regulation of MSCs.Studies have revealed that the immune regulation of MSCs has strong plasticity.Such plasticity depends on the regulatory network formed between cytokines,chemokines and some small molecules between immune cells and MSCs.IFN-? is an important pro-inflammatory factor secreted mainly by T cells.It can induce MSCs to produce anti-inflammatory factors(such as IDO,PD-L1.)at a certain concentration to inhibit inflammation.In addition,we also found that IFN-?-induced changes in glucose metabolism in MSCs suggest that there is a potential correlation between immune regulation and glucose metabolism in MSCs,and no studies have been reported.The Warburg effect was discovered by the German biochemist Warburg in 1920.It is an abnormal glycolytic reaction of liver cancer cells,which is characterized by high glucose uptake,active glycolysis,and a large amount of lactic acid metabolites.The metabolic characteristics are aerobic glycolysis.It has been demonstrated that most tumor cells are characterized by this effect in terms of glucose metabolism.In addition,metabolic changes have also been observed in the process of macrophage polarization to M2.PDK1,a key regulator of glucose metabolism,is involved in the regulation of macrophage polarization,and when PDK1 is knocked down,it promotes the conversion of macrophages to M2.Glycolysis is the main metabolic pathway during resting state ofstem cell,and whether IFN-?-induced immunoregulatory MSCs undergo metabolic reprogramming,and the effect of this change on its immune regulation function is still unclear.Therefore,this study aimed to investigate the role of glucose metabolism in the immunomodulatory ability of MSCs and its molecular mechanism,and provide a basis for clinical improvement of MSCs treatment.ObjectiveThis study intends to study the relationship between conversion of glucose metabolism and immunomodulatory capacity of MSCs from molecular mechanism and function.On the one hand,the specific relationship is clarified,and whether conversion of glucose metabolism affects the secretion of anti-inflammatory factors by MSCs;on the other hand,this relationship is functionally verified to investigate whether the effect of conversion of glucose metabolism on the immunomodulatory capacity of MSCs is reflected in the inhibition of T cell proliferation.MethodsThe MSCs were treated with si PDHA1(pyruvate dehydrogenase ?1 subunit)to prepare aerobic oxidative deficient MSCs.Seahorse and mixed lymphocyte assays were used to detect the glucose metabolism status of MSCs treated with or without IFN-? and their inhibitory effects on T cells.qPCR was used to detect the expression of IDO and PD-L1 at the transcriptional level of MSCs treated with or without IFN-?.Western Blot assay for protein expression of IDO and PD-L1 in wild-type or aerobic oxidative deficient MSCs treated with or without IFN-?,and the expression of IDO and PD-L1 by IFN-?-stimulated aerobic oxidative deficient MSCs after addition of ATP.ResultsIFN-?-induced MSCs showed decreased glycolysis,enhanced oxidative phosphorylation,upregulation of IDO and PD-L1 expression,and increased ability to inhibit T cell proliferation.The treatment of si PDHA1 can significantly attenuate the above biological phenomena,and at the same time reduce the ATP level of MSCs.On this basis,replenishing ATP can partially reverse its effect,thereby restoring anti-inflammatory function.Conclusion1.IFN-? can induce MSCs to transform into anti-inflammatory phenotype,simultaneous metabolic reprogramming,weakened glycolysis,enhanced oxidative phosphorylation.2.PDH is dependent on ATP involved in the regulation of the plasticity of IFN-?-induced immunomodulatory capacity of MSCs.