Fetal loss due to Th1-skewed Th1/Th2 balance with increase (not decrease) of regulatory T cells in abortion-prone...

Area of Science:

• Immunology
• Reproductive Biology

Background:

• Pregnancy involves a complex immune balance, with Th1/Th2 cytokine profiles and regulatory T (Treg) cells playing critical roles.
• Dysregulation of these immune components is implicated in pregnancy complications, including fetal loss.

Purpose of the Study:

• To investigate the impact of modulating the Th1/Th2 cell ratio and Treg cell percentage on pregnancy maintenance in an abortion-prone mouse model.
• To explore the potential of specific immune modulators to influence pregnancy outcomes.

Main Methods:

• An abortion-prone mouse model (CBA/J female x DBA/2JJcl male) was utilized.
• Mice were treated with Dermatophagoides farinae (Df) extract or keyhole limpet hemocyanin (KLH) combined with a squalene-based adjuvant (SquA).
• Immune cell profiles (Th1/Th2 ratio, Treg percentage) and fetal death rates were assessed post-treatment and mating.

Main Results:

• Df extract treatment decreased the Th1/Th2 cell ratio and increased Treg cells, leading to reduced fetal death rates.
• KLH treatment enhanced Th1 bias and increased fetal death rates, despite also increasing Treg cells.
• A strong positive correlation was observed between the Th1/Th2 cell ratio and fetal death rate.

Conclusions:

• Modulating the Th1/Th2 cell ratio significantly impacts pregnancy maintenance, with a lower ratio associated with better outcomes.
• Regulatory T (Treg) cells may play a role in preventing excessive Th1/Th2 imbalance rather than solely inducing maternal tolerance.
• These findings highlight the critical role of immune balance in successful pregnancy and suggest potential therapeutic targets for pregnancy complications.