mregDCs induce abnormal T cell functions in endometriosis

Endometriosis has a metastatic implantation biology as malignant tumors and an immunological environment as immune escape. However, the role of dendritic cells (DCs) in endometriosis is still unknown. We applied single-cell RNA sequencing (scRNA-seq) on eutopic endometrium and ectopic lesions to dissect heterogeneity within DCs subsets. ScRNA-seq data in public database was also included in the analysis. Flow cytometry was used to identify the presence of ‘mature DCs enriched in immunoregulatory molecules’ (mregDCs) in patient tissues. Multiplex immunofluorescence tissue staining was adopted to show the presence of mregDCs. To further explore the function of mregDCs in endometriosis, mregDCs and naïve CD4+ T cells were sorted by fluorescence activated cell sorting (FACS) and co-cultured. carboxyfluorescein succinimidyl ester (CFSE) assays and intracellular cytokine staining assays were employed to detect proliferation and differentiation ability of naïve CD4+ T cells in vitro. The proportions of T cell subsets in the ectopic lesions of mice following peritoneal transfusion of mregDCs were measured in vivo in a mouse model for endometriosis. ScRNA-seq data analysis displayed the substantial alterations and heterogeneity of DCs subsets in endometriosis. The proportion of mregDCs were up-regulated in the endometriosis scRNA-seq data. Flow cytometry and immunofluorescence staining confirmed the presence and upregulation of the mregDCs in ectopic lesions. The co-cultured experiment showed that endometriosis-associated mregDCs have the ability to induce naïve CD4+ T cells proliferation and differentiating as Th2 and iTregs. After peritoneal transfusion of mregDCs into endometriosis mouse model, the number of Th2 in ectopic lesion increased significantly. Our research revealed the heterogeneity of DCs landscape in endometriosis in single cell level. We found the specific mregDC celltype may participate in the abnormal inflammation environment in endometriosis and exert profound immunostimulatory and regulatory changes in T cells function.