Suen JL, Chang Y, Shiu YS, et al. - In this study, researchers investigated the cellular source and angiogenic activity of local IL-10 during the early stage of endometriosis. Using a surgical murine model, it was observed that localized treatment with exogenous recombinant IL-10 on the day of surgery considerably improved endometriotic lesion growth and angiogenesis, whereas blocking local IL-10 activity using mAbs notably suppressed those impacts. Adoptive transfer of Il10^+/+ plasmacytoid dendritic cells into mice considerably improved lesion development, whereas Il10^-/- plasmacytoid dendritic cells markedly restrained lesion development. Moreover, in vitro angiogenesis analyses exhibited that the IL-10 and IL-10 receptor pathway aroused the migratory and tube formation ability of HUVECs as well as ectopic endometrial mesenchymal stem cells through a VEGF-dependent pathway at least in part. It was also discovered that recombinant IL-10 directly stimulated angiogenesis, on the basis of a Matrigel plug assay as well as a zebrafish model. In comparison with the corresponding normal counterparts, the enhanced infiltration of CD123+ plasmacytoid dendritic cells and greater percentages of cells that express the IL-10 receptor and CD31 was explicated by pathological outcomes from human endometrioma tissues. In conclusion, through pathological angiogenesis during the early disease stage, these outcomes reveal that IL-10 secreted from local plasmacytoid dendritic cells supports the development of endometriosis. Furthermore, the study gives a scientific basis for a possible therapeutic approach that targets the IL-10—IL-10 receptor pathway in the endometriotic milieu.