Prenatal Exposure to Bacterial Extracellular Vesicles Influences Fetal Gut Immunity and Immune Programming

Area of Science:

• Immunology
• Developmental Biology
• Microbiology

Background:

• The fetal immune system develops during gestation to prepare for life outside the womb.
• Bacterial extracellular vesicles (bEVs) are bacterial particles that can influence host immunity.
• The impact of bEVs on fetal intestinal immune development is not well understood.

Purpose of the Study:

• To investigate how bEV exposure affects immune cells in the fetal mouse gut.
• To understand bEVs' role in priming intestinal immunity and immune cell differentiation.
• To compare these effects in normal and germ-free environments.

Main Methods:

• Fetal mice received bEVs via intra-amniotic injection.
• Mice were raised in normal or germ-free conditions.
• Immune cells in fetal and neonatal gut tissues were analyzed using mass cytometry (CyTOF).

Main Results:

• bEVs increased intestinal stem cells (ISCs), promoting differentiation into Paneth and tuft cells.
• bEVs promoted lymphoid and myeloid progenitor development, biasing them towards antigen presentation.
• Germ-free models showed increased sensitivity to bEVs, with altered immune cell responses.

Conclusions:

• bEVs are crucial for shaping fetal intestinal immunity by priming immune progenitors and enhancing ISC function.
• These findings suggest potential uses for bEVs in immunomodulation and vaccine development.
• Further research is needed to explore the functional and translational aspects of bEV-primed immune cells.