Gut microbiota‑immune crosstalk in recurrent pregnancy loss: Mechanisms and therapeutic perspectives (Review)

Recent studies have indicated the relationships between the human reproductive system, gut microbiota and immune crosstalk. These interactions can influence pregnancy outcomes, which occasionally result in adverse consequences for the mother and fetus. However, key questions remain unresolved, such as identifying the microbiota capable of modulating immune cells during pregnancy. The present review aimed to investigate the relationship between microbiota and T cell types and to clarify the mechanism through which these interactions occur. In pregnancy‑related disease models, it is still unclear whether T helper cell (Th17)/regulatory T cells (Treg cells) are generated in situ or migrate into inflamed tissues. The present review explored the association of gastrointestinal dysbiosis with the female reproductive system and the role of the maternal‑fetal interface. In particular, the effect of gut microbiota‑derived short‑chain fatty acids, bile acids, indoles and their derivatives on immune signaling networks is discussed. Furthermore, the effects of these networks on infectious, metabolic and female pregnancy periods are summarized. Finally, the translational potential of modulating gut microbiota through probiotics and dietary interventions to restore immune homeostasis and improve pregnancy outcomes in Recurrent pregnancy loss (RPL) is also evaluated. The present review aimed to assist patients in developing a more profound comprehension of the underlying causes of unexplained RPL and broaden the spectrum of potential therapeutic strategies for infertility.