Role of Th1, Th2, Th17, and regulatory T cells in endometriosis

Innate immune system is a rapidly reactive system that responds immediately to infectious or other nonself-agents, thereby inducing inflammatory response to protect the host until the generation of slower adaptive immune system. Macrophages, dendritic cells, and toll-like receptors (TLRs) are integral components of the innate immune system. In contrast, T-helper (Th1/Th2/Th17) cells and regulatory T (Treg) cells are the prime components of adaptive immune system. Studies showed that the growth and progression of endometriosis continue even in ovariectomized animal. This indicates that besides ovarian steroid hormones, the growth of endometriosis can be regulated by innate/adaptive immune system in pelvic environment. With the progression of immunology research, recent reports demonstrated a potential role of Th1/Th2/Th17/Treg cells either alone or in combination in the initiation, maintenance, and progression of endometriosis. In this review article, we discussed the role of innate immunity and adaptive immunity in endometriosis on the basis of updated human study and experimental evidence in animal model.