#323 : Prednisone Distinctively Suppresses Cytotoxic, Regulatory and Pro-Inflammatory Uterine Immune Cells in Women with Reproductive Failure

Background and Aims: The use of immunosuppressive corticosteroid drugs such as prednisone is of great interest in improving pregnancy outcomes for women with reproductive failure. However, the impact of prednisone on endometrial immune cells remains unclear, and there is controversy over its therapeutic benefits. Our study aims to compare the changes in the levels of cytotoxic, regulatory, and pro-inflammatory endometrial immune cells during the window of implantation before and after the treatment with prednisone. Method: Endometrium samples were collected from 22 women with repeated implantation or recurrent miscarriage on the day of LH surge plus 7. The endometrium samples were simultaneously stained with a panel of antibodies to identify various types of endometrial immune cells, including cytotoxic CD3−CD56+CD16+ uNK cells and CD3+CD56+ NK-like T cells, regulatory CD3−CD56+CD16− uNK cells, pro-inflammatory CD16+CD68+ macrophages, and CD3+ pan-T cells. The differences in these immune cell populations before and after oral prednisone treatment (10 mg/day from the first day of their menstrual cycle until the day of biopsy) were compared. Results: Prednisone significantly decreased the density of cytotoxic CD3+CD56+NK-like T cells (0.09±0.03% vs. 0.04±0.02%, P=0.04), regulatory CD3−CD56+CD16− uNK cells (3.20± 1.52% vs. 1.60± 0.75%, P=0.02) and pro-inflammatory CD16+CD68+ macrophages (0.2± 0.07% vs. 0.07± 0.02%, P=0.03). However, there was no significant fluctuation in cytotoxic CD3−CD56+CD16+ uNK cells (0.08± 0.02% vs. 0.05± 0.03%, P=0.15) and pan-T cells (0.91± 0.56% vs. 0.83± 0.55%, P=0.58). Conclusion: The treatment with prednisone can reduce the levels of certain types of immune cells in the endometrium, specifically cytotoxic NK-like T cells, regulatory uNK cells, and pro-inflammatory macrophages. This selective suppression of endometrial immune cells by prednisone suggests that it may be possible to identify and target specific immune cells for more precise treatments in future clinical trials.