Abortion in AhR-knockout mice and fetomaternal immunity

Area of Science:

• Immunology
• Developmental Biology
• Genetics

Background:

• The Aryl hydrocarbon receptor (AhR) plays a crucial role in various physiological processes.
• AhR knockout (AhR-KO) mice exhibit reduced litter sizes, suggesting reproductive complications.
• The precise mechanisms underlying AhR deficiency-related fetal mortality remain unclear.

Purpose of the Study:

• To investigate the impact of maternal AhR gene defects on fetal survival and reproductive outcomes.
• To elucidate the molecular mechanisms, particularly immune tolerance pathways, affected by AhR deficiency during pregnancy.
• To determine the role of maternal genotype versus fetal genotype in AhR-related fetal loss.

Main Methods:

• Comparative analysis of litter sizes and fetal mortality in AhR-KO and wild-type mice.
• Assessment of gene expression (mRNA levels) for immune tolerance markers (FoxP3, IDO1) and inflammatory cytokines (IL-1β, IFN-γ, IL-6) in placental and fetal tissues.
• Evaluation of reproductive outcomes in both syngeneic and allogeneic pregnancy models.

Main Results:

• AhR-KO dams showed decreased litter sizes and increased fetal deaths, linked solely to maternal genotype.
• Placentas from AhR-KO dams exhibited reduced mRNA levels of immune tolerance genes FoxP3 and indoleamine 2,3-dioxygenase-1 (IDO1).
• Elevated mRNA levels of pro-inflammatory cytokines IL-1β and IFN-γ were observed in AhR-KO placentas, alongside reduced IL-6 and IDO1 expression.

Conclusions:

• Maternal AhR deficiency disrupts fetal-maternal immune tolerance, leading to increased placental inflammation and fetal loss.
• Reduced expression of FoxP3 and IDO1, coupled with heightened IL-1β and IFN-γ, contributes to pregnancy complications in AhR-KO mice.
• AhR signaling is critical for maintaining immune homeostasis during pregnancy, and its absence impairs reproductive success.