Ovulation as danger signaling event of innate immunity

Katharina Spanel-Borowski (1)

1 Leipzig University / Universität Leipzig

The ovulatory process is characterized by tissue wounding and, after oocyte expulsion, by healing being connected to the formation of a corpus luteum (CL). The ovulatory event thus compares with a sterile inflammation. The concept is forwarded that the ovulatory process depends on innate immunity (INIM) function. The ultimate trigger for INIM signaling are danger signals/alarmins from granulosa cells damaged by oxidative stress and reactive oxygen species (ROS), respectively. Alarmins like oxidized low density lipoprotein (oxLDL) are recognized by cytokeratin-positive (CK) granulosa cells with the expression of toll-like receptor 4 (TLR4). The subsequent inside-out signaling from the antrum towards the thecal cell layer comprises inflammation and tissue disintegration, which might be dominated by the myeloid differentiation factor 88 (Myd88) gateway. Additive or co-regulatory function are expected from the complement cascade for vessel permeability and leukocyte immigration and the wingless (WnT)-signaling for cell adhesion of CK granulosa cells. The outside-in-signaling relates to the repair phase, which is primarily controlled by the TIR-domain-containing adaptor protein producing IFN type I (TRIF) gateway of TLR signaling. The KIT/CD117 tyrosine kinase receptor and the tachykinin-tachykinin receptor system could be involved. The appealing concept of INIM function in the ovary is novel and inaugurates a novel research field.

Mots clés: Ovulation; preovulatory follicle; oxidative stress; innate immunity; cytokeratin-positive granulosa cells; toll-like receptor 4; signaling pathways

Katharina Spanel-Borowski. Ovulation as danger signaling event of innate immunity. Molecular and Cellular Endocrinology, 2011, 333 (1), pp.1. ⟨10.1016/j.mce.2010.12.008⟩. ⟨hal-00660887⟩