Abstract
The study aimed to explore the relationship between the expression of cytochrome P450 family 27 subfamily B member 1 (CYP27B1), vitamin D, and impaired T cell subsets in recurrent spontaneous miscarriage (RSM). A Total of 779 healthy women of childbearing age and 1031 women with a history of RSM were involved in this study. The results of flow cytometry showed that the proportion of Tregs was higher in healthy women than in the women with RSM. For cytokines, the levels of interleukin-17 (IL-17) and interferon-gamma (IFN-γ) were significantly higher in RSM patients than in healthy women, while IL-10 was notably lower in RSM patients. Furthermore, compared to healthy individuals, RSM patients had lower levels of serum 25(OH)D detected by chemiluminescence. The frequency of Tregs was negatively correlated with 25(OH)D. Specifically, for every 10 ng/ml increase in 25(OH)D, the percentage of Tregs increased by 0.58 as calculated. IL-17 and IFN-γ were inversely correlated with 25(OH)D, while the serum interleukin-10 (IL-10) level was positively correlated with 25(OH)D. CYP27B1 was found to be expressed in both cytotrophoblast and extracellular villi trophoblast cells. However, reduced expression of CYP27B1 was observed in the placenta with RSM. Notably, the level of 25(OH)D increased in the supernatant of CYP27B1 knockdown BeWo compared to normal cells, while human chorionic gonadotropin (hCG) was significantly reduced. The hCG secretion of CYP27B1 KO BeWo cells was partially restored after 1,25(OH)2D3 supplementation. In addition, 1,25(OH)2D3 treatment could induce more CD4+ T cells to convert to Foxp3+iTreg, which in turn inhibited the secretion of IL-17, IFN-γ. In summary, this research unveiled a connection between reduced CYP27B1 and vitamin D deficiency in RSM. Our study underscores the potential benefits of vitamin D treatment supplementation in the context of RSM. However, it is important to note that further research is imperative to validate these observations.