Regulatory T cells in bovine fertility: Current understanding and future prospects.

Regulatory T cells (Tregs) have emerged as crucial players in maintaining maternal-fetal tolerance and promoting successful pregnancy outcomes. This review examines the importance of these cells in pregnancy, drawing on human and animal-based studies, with a focus on their role in bovine fertility. Tregs employ various mechanisms to mediate maternal-fetal tolerance, including regulation of effector T-cell responses, interactions with innate immune cells in the uterine microenvironment, and modulation of trophoblast function. In humans, Treg dynamics during normal pregnancy and alterations in pregnancy complications provide compelling evidence for their involvement in maintaining fetal-maternal harmony. Animal models, particularly mouse studies, have further elucidated the importance of Tregs in preventing fetal rejection and promoting successful pregnancy outcomes. The review also explores the characterization of bovine Tregs, highlighting their similarities and unique features compared to human and rodent counterparts. Recent studies have indicated the presence and potential significance of Tregs in the bovine uterine environment during early pregnancy. Translational applications of Treg research in livestock fertility are discussed, with a focus on immunomodulatory strategies for enhancing Treg function, such as antigen-specific tolerance induction, pharmacological targeting of Treg pathways, and cell-based therapies using autologous or allogeneic Tregs. The review concludes by emphasizing the potential impact of Treg-based strategies on the livestock industry and the broader implications for human reproductive health. Future research directions are outlined, underscoring the need for further investigations into the role of Tregs in bovine reproductive tissues and their relationship with fertility outcomes.