Cell Communications Between GCs and Macrophages Contribute to the Residence of Macrophage in Preovulatory Follicles

There were not only granulosa cells (GCs) but also immune cells in preovulatory follicular fluid. The objective of this study was to explore the interactions between macrophages and GCs via adhesion molecules in preovulatory follicles and the regulatory mechanisms of the interactions.

Flow cytometry and immunofluorescence were used to detect the expression of ITGB1 in macrophages and fibronectin (FN)1 in GCs in preovulatory follicles from 12 patients. The synthesis of FN1 protein in human ovarian GCs line (KGN) was detected by western blot. An adhesion experiment was performed to observe the changes of KGN cells adhesion to macrophages.

The progesterone levels 12 h after human chorionic gonadotropin (HCG) administration in the high proportion immune cells (high immune [HI]) group were significantly higher than that in the low proportion immune cells (low immune [LI]) group (p < 0.0001). The expression of ITGB1 in macrophages in the HI group was higher than in the LI group. The expression of FN1 in GCs in HI group was higher than in LI group (p < 0.01). Progesterone increased the synthesis of FN1 in KGN cells (p < 0.0001) and was suppressed by the elimination of PGR. The adhesion effect of KGN cells on macrophages was enhanced by progesterone (p < 0.0001).

After luteinizing hormone (LH)/HCG surge, progesterone promotes the expression of FN1 in GCs by acting on the receptor PGR, and then GCs enhance the adhesion of macrophages by FN1-ITGB1 interaction, further leading to the result that macrophages perform diverse functional activities to maintain tissue homeostasis during ovulation.