Single-cell Raman trapping analysis revealed immunometabolism changes in peritoneal fluid in endometriosis

In endometriosis, an aberrant immune response in the peritoneal environment is evident, but the underlying mechanism remains unclear. In recent years, some emerging data support an important role for the changes in intracellular metabolic pathways of immune cells in controlling their function. In this study, we aim to investigate the phenotypic and immunometabolism profiling of peritoneal fluid cells in endometriosis patients. By flow cytometry, our results show phenotypic profiling of peritoneal fluid cells with higher percentages of CD45⁺, CD3⁺, CD3⁺CD8⁺, CD3⁺CD56^+, and CD14⁺CD68⁺ cells and the ratio of M2 to M1 macrophages but less CD14^?CD86⁺ dendritic cells in endometriosis when compared with control. Label-free single-cell Raman trapping analysis shows intracellular changes in decreased collagen, proteins and lipids levels in CD45⁺ immune cells in endometriosis. In the supernatant of peritoneal fluid from endometriosis patients, Raman results reveal extracellular decreased protein and carbohydrate levels but increased lipid and fatty acid levels. Especially, Raman bands indicate both intracellular and extracellular levels of cholesterol and carotenoids decrease in endometriosis patients when compared with controls. This study provides immunometabolism features of the specific microenvironment in the peritoneal cavity and identifies some biological molecules associated with immune dysfunction in endometriosis, which may offer new clues for understanding disease pathology and therapeutic targets.