Endometriosis and the lympathic system: lymph nodes draining the uterus and deep infiltrating endometriotic lesions of the bowel

Endometriosis is associated with locally dysregulated immune responses and increased lymphangiogenesis. This study aimed to examine endometrial-like cells and immune cell populations in uterine-draining iliac lymph nodes throughout the menstrual cycle and lymph nodes associated with deep infiltrating endometriotic lesions of the bowel. \n \nParaffin-embedded uterine-draining iliac lymph nodes (endometriosis = 6, control = 9) and deep infiltrating bowel endometriotic lesion-associated nodes (n = 12) were immunohistochemically stained for endometrial-like cells and a range of immune cells. \n \nIn uterine-draining iliac nodes, DC-Sign+ cell numbers and CD4 antigen expression peaked during menstruation, and CD20 antigen expression significantly decreased between the proliferative and secretory phases. In deep infiltrating bowel endometriosis associated nodes, CD10+ endometrial-like cells were decreased compared to iliac nodes; CD4+ numbers, and CD4 and FoxP3 antigen expression were increased but DC-Lamp+, CD20+ and CD57+ numbers and DC-Lamp, CD79 and CD57 antigen expression were decreased. \n \nThe presence of endometrial-like cells and dysregulated immune cell environment in pelvic lymph nodes indicate an important role for the lymphatic system in endometriosis. This study provides new evidence for lymphatic and immune system involvement in the development and progression of endometriosis, which may open up new venues for exploring lymphatic-based therapeutic approaches.