Metabolomics And Proteomics Analyses Reveal The Characteristics Of Human Decidual NK Cells

Natural killer(NK)cells,which are components of the natural immune system,are abundantly enriched in the decidual tissue at the maternal-fetal interface following pregnancy.This is where the decidualized endometrium(decidua)and trophoblast cells come together to form the maternal-fetal interface.The development of the embryo as well as maternal-fetal immunological tolerance are significantly influenced by decidual natural killer cells(dNK).It has been discovered that the immunological characteristics of dNK differ significantly from those of human peripheral blood NK(pNK)cells,however the exact mechanism is unknown.In this study,we sorted and purified normal human early pregnancy dNK and peripheral blood pNK cells,then used metabolomics and proteomics techniques to compare the metabolic profiles and protein expression patterns of the two groups of cells in order to better understand the immunological properties of dNK.Metabolomic study found that 77 metabolites were significantly changed in dNK cells.A notable difference between dNK and pNK cells was the amount of metabolites involved in the metabolism of glutathione and glycerophospholipids.Glycerophospholipids,which included 24 different metabolites,were the most abundant type of metabolites altered in dNK cells.In dNK cells,there was a considerable decrease in phosphatidylcholine(PC),lysophosphatidylcholine(LPC),phosphatidylethanolamine(PE),and lysophosphatidylethanolamine(LPE).According to a proteomic investigation,394 proteins were expressed differently in dNK cells.According to GO enrichment analysis of differentially expressed proteins,a high number of these proteins were primarily enriched in the pathways for "NK cell-mediated cytotoxicity," "protein processing in the endoplasmic reticulum," "oxidoreductase activity," and "fatty acid metabolism." Additionally,we discovered a few proteins with differentially expressed cytoskeletal rearrangement-related sequences that seem to be linked to increased cytokine release and decreased dNK cell toxicity.In the "protein processing of endoplasmic reticulum" pathway,which is most dramatically elevated by dNK cells,we identified the most significantly altered differential protein CKAP4 in the pathway and confirmed it in vitro and in vivo.We discovered that the deletion of CKAP4 resulted in decreased cytokine release by NK cells under stress.Finally,comprehensive proteomics and metabolomics analyses showed that glycerophospholipid metabolism downregulation decreased NK cell cytotoxicity.Furthermore,the combined research demonstrated a link between redox imbalance in dNK cells and changes in differential metabolites.In contrast to pNK cells,dNK cells had much lower levels of glutathione metabolism,and an intracellular redox imbalance was caused by elevated ROS levels.Overall,our study offers information on the proteome and metabolomic profiles of human dNK and pNK cells.Our findings reveal that human dNK cells have unique metabolic and protein expression patterns,which will create the theoretical groundwork for further unraveling the regulatory mechanisms of regional immunological features of dNK cells.This will be critical for a thorough knowledge of the mechanisms behind the onset of immune tolerance in pregnancy,as well as creating the theoretical foundation and offering new hints for clinical immunotherapy with NK cells.