Defining Functional Contributions of Lyve1 Macrophages Residing in Endometriosis Lesions

Macrophages are specialized phagocytes and play a crucial role in maintaining tissue homeostasis. In endometriosis, a chronic inflammatory condition within the pelvic cavity, macrophages have been implicated in driving the progression of endometriotic lesions. Recent findings suggest ontogenetic heterogeneity and distinct roles of lesion-resident macrophages, but specific functions of subsets are yet to be defined. Here, we employ intraperitoneal transplantation of endometrial tissue from a reporter mouse into binary transgenic ‘splitCre’ animals to enable visualization, characterization and mutagenesis of genetically defined macrophage subpopulations. Specifically, this approach allows us to investigate the role of specific subsets of macrophages at various stages of the disease. Our first objective was to identify targeted tissue-resident macrophages in the pelvis of splitCre mice, establish a suitable disease model and determine whether targeted macrophages could be recruited to the lesion microenvironment. Through histological imaging and flow cytometry, we revealed that our Lyve1/CX splitCre model effectively targets tissue-resident macrophages within the abdominal wall, peritoneal fluids, and mesentery. Moreover, a substantial presence of targeted cells was observed surrounding endometriotic lesions, irrespective of their anatomical location. Interestingly, our findings suggest that Lyve1 MF are unlikely to originate from the eutopic endometrium, but rather infiltrate the lesions from the peritoneal fluids. Collectively, we have successfully established a robust endometriosis model to delve deeper into the functions of specific subsets of lesion-resident Lyve1 macrophages. Our forthcoming focus will involve studying Lyve1 MF translatome using the RiboTag approach to define their functional contribution to lesion establishment and maintenance.