Human labour is associated with altered regulatory T cell function and maternal immune activation

Area of Science:

• Immunology
• Reproductive Biology
• Maternal-Fetal Medicine

Background:

• Pregnancy involves enhanced regulatory T cell (Treg) function and suppressed immune activation to support feto-placental development.
• The maternal immune system undergoes significant adaptations during pregnancy.

Purpose of the Study:

• To investigate if human labor onset reverses pregnancy-induced maternal immune changes.
• To test the hypothesis that labor is associated with decreased Treg function, particularly in modulating Toll-like receptor (TLR)-induced responses.

Main Methods:

• Studied peripheral blood, myometrial cells (myoMC), and cord blood mononuclear cells (CBMC) at labor onset.
• Assessed changes in cell number, activation status, and functional behavior of immune cells.
• Evaluated Treg function in modulating TLR-induced immune responses.

Main Results:

• Treg function declines with labor onset, and their cellular targets shift.
• Increased activation of myoMC (MHC class II expression) and CBMC inflammatory cells observed.
• Innate immune system activation increased, indicated by altered monocyte and neutrophil phenotypes.

Conclusions:

• Human labor onset involves a reversal of pregnancy-induced immune adaptations.
• Declining Treg function and heightened innate immunity may contribute to labor initiation.
• Immune system shifts prepare for postpartum events like microbial invasion or tissue remodeling.