Co-expression of activating and inhibitory receptors on peritoneal fluid NK cells in women with endometriosis

Synergy between Th1 and Th2 responses during endometriosis: A review of current understanding

Endometriosis is widely perceived as an estrogen-dependent chronic disorder with infertility and pelvic pain. Although the etiology of endometriosis has remained elusive, many studies have proclaimed the relevance of immune system disorders with endometriosis. With the discovery that the dysregulation of multiple biological functions in endometriosis is caused by the aberrant differentiation of T helper cells, a shift towards Th2 immune response may account for the disease progression. This review attempts to present mechanisms of cytokines, chemokines, signal pathways, transcription factors and some other factors related with the derivation of Th1/Th2 immune response involved in the development of endometriosis. The current understanding of treatment approaches and potential therapeutic targets will also be outlined with brief discussion.

Natural Killer Cell Receptors and Endometriosis: A Systematic Review

Endometriosis is a chronic inflammatory disorder, characterized by the presence of endometrial cells outside the uterine cavity. An increasing number of studies correlate the immune system with endometriosis, particularly NK receptors (NKR), which have been suggested to play an essential role in the pathogenesis of the disease. This systematic review aims to enlighten the role of NKR in endometriosis. A literature search was performed independently by two reviewers, to identify studies assessing the role of NKR in endometriosis. In total, 18 studies were included. Endometriosis pathogenesis seems to be marked by the overexpression of NK inhibitor receptors (KIRS), namely, CD158a+, KIR2DL1, CD94/NKG2A, PD-1, NKB1, and EB6, and inhibiting ligands such as PD-L1, HLA-E, HLA-G, and HLA-I. Concurrently, there is a decrease in NK-activating receptors and natural cytotoxicity receptors (NCRs), such as NKp46, NKp30, and NKG2D. The immune shift from NK surveillance to NK suppression is also apparent in the greater relative number of ITIM domains compared with ITAM domains in NKRs. In conclusion, NK receptor activity seems to dictate the immunocompetency of women to clear endometriotic cells from the peritoneal cavity. Future research could explore NKRs as therapeutic targets, such as that which is now well established in cancer therapy through immunotherapy.