The Effect of Vitamin D Metabolic Status and Endometrial Immune Patterns on the Outcomes of ART Programs
Authors: Chukhnina Elena , Kazachkov Evgeny , Voropaeva Ekaterina , Kazachkova Ella , Polina Miroslava , Douglas Natalya 
Published: June 2021

The objective of this study was to assess the possibility of predicting the outcomes of in vitro fertilization (IVF) and IVF/ICSI (intracytoplasmic injection [transfer] of sperm into eggs), protocols based on the serum vitamin D content and endometrial expression of vitamin D receptor (VDR), CD4+T cells, and CD8+T cells.	Methods and Results: The results of IVF and IVF/ICSI programs were analyzed in 147 patients of older reproductive age (36-44 years of age) with tubal-peritoneal factor of infertility. Depending on the outcomes of ART programs, 2 groups were formed. Group 1 included 37 women with the onset of pregnancy; Group 2 included 110 women with negative outcomes of ART programs.	The level of 25(OH)D in the blood serum and follicular fluid (FF) was assessed. The sampling of the material (blood and FF) was carried out on the day of ovarian puncture, the 25(OH)D content – at least three days after the last administration of the drug. Anti-Müllerian hormone (AMH) was determined using AMH reagent (AMH Gen II ELISA) and the Beckman Coulter Access® 2 Immunoassay System (Beckman Coulter, Inc. USA). Morphological examination of the endometrium was performed after biopsy sampling by pipelle biopsy on Day 7 after confirmed ovulation in the cycle preceding ART. The endometrial expression of VDR, CD4+Tcells, and CD8+Tcells was evaluated in 68 women of the sample: 18 – with pregnancy, 50 – with negative outcomes in ART programs.	Vitamin D deficiency (<20ng/ml) in peripheral blood was detected only in Group 2. Low levels of vitamin D (20-<30ng/ml) in women of this group were four times more frequent (p=0.008) than in Group 1. Women with the onset of clinical pregnancy were more often distinguished by the optimal content of vitamin D in biological fluids – almost twice as much as those with ineffective attempts to treat infertility (P=0.009 for peripheral blood). The mean value of the 25(OH)D content in the blood serum in both groups did not differ; in FF it was significantly higher in Group 1 than in Group 2 (p = 0.003). A strong correlation was revealed between the content of 25(OH)D in the blood serum and FF (r=0.67, P=0.003 in both groups), a weak correlation – in cases where it was impossible to sample oocytes and/or embryos (r=0.48, P=0.06). The VDR expression in stromal epithelium was higher in Group 2 than in Group 1 (P=0,016). It is calculated that a 1% decrease in VDR expression in the stroma increases the chance of a favorable outcome by 1.35 times.The density of labels of CD4+T cells and CD8+T cells in the endometrial stroma did not differ significantly between groups. The expression of CD4+T cells and CD8+T cells in endometrial samples taken from the same infertile women in different phases of the menstrual cycle showed no statistically significant differences.	Conclusion: Morphofunctional peculiarities of the endometrium of infertile women are the basis for predicting the outcomes of ART programs and preparing for pregnancy.