Characterisation of circulating and endometrial dendritic cell populations in fertile and infertile women with and without endometriosis

Endometrial dendritic cells (DCs) play important roles in regulating cyclical changes in the endometrium. DCs are a heterogeneous population of immune cells that initiate and regulate immune responses. Dysregulation of endometrial DCs is indicated in endometriosis (affects 10-15% of reproductive aged women) and fertility disturbances. However, detailed knowledge of changes in DC populations in endometriosis and associated infertility is lacking. Therefore, this study aimed was to characterise peripheral and endometrial DCs in fertile and infertile women with and without endometriosis using multi-colour flow cytometry and immunohistochemistry. \n \nIn women with endometriosis, circulating CD1c+ myeloid DCs (mDCs) significantly decreased from menstruation into the proliferative phase and endometrial IRF-8+ pDC density was decreased during menstruation. In infertile women, circulating CD2- pDCs and endometrial IRF-8+ pDCs were reduced during the secretory phase compared to fertile women. In infertile women with endometriosis, circulating CD11c+ mDCs and endometrial IRF-8+ pDCs were significantly decreased during the secretory phase. \n \nThe observed increased inflammatory and decreased tolerogenic circulating DC, and decreased tolerogenic endometrial DC, may contribute to endometriosis pathogenesis and associated infertility. This study provides a further understanding of the immune mechanisms in endometriosis and infertility. Immunological treatment might one day be effective in endometriosis-associated infertility.