A research team from the University of Oulu in Finland has shown that nanoparticles derived from maternal gut bacteria are present in the amniotic fluid. This is a previously unknown mechanism of communication between the maternal gut microbiome and the fetus.
The identified nanoparticles are extracellular vesicles secreted by cells. Vesicles secreted by bacteria contain cell-derived molecules, such as proteins, DNA, RNA, and metabolic products. These nanoparticles play an important role in bacterial communication.
The study involved 25 mothers who gave birth by cesarean section at Oulu University Hospital. Studies have shown that nanoparticles found in amniotic fluid and maternal feces are similar in terms of bacterial species and content. The research was refined in an experimental animal model, where it was found that extracellular vesicles isolated from human maternal feces are transferred to the fetus.
The results of recent studies may provide answers to questions that have puzzled the scientific community for a long time: whether a healthy fetus is exposed to bacteria during pregnancy and whether the fetal environment has its own microbiota.
According to our research, in healthy pregnancies, nanoparticles secreted by maternal gut bacteria are transferred into the amniotic fluid, which contains bacteria-derived molecules. Vesicles do not cause infection like all bacteria. In this way, the fetus is safely exposed to the mother’s normal gut microbiome before birth. “The mechanism we found may play an important role in the development of the fetal immune system during pregnancy.”
Anna Kaisanlati, Doctoral Researcher, University of Oulu
Nanoparticles produced by maternal gut bacteria may be important for fetal immune system development. They can safely prepare the fetus for the moment of birth, when the fetal gut quickly acquires its own microbiota. The finding opens the door to further research. “It would be interesting to study how the interaction between maternal gut bacteria and the fetus during pregnancy affects the health of the offspring later in life,” Kaysanlati reflects.
The study was conducted by the research team of Prof. Terry Tapiainen and Docent Justus Reunanen at Oulu University Faculty of Medicine and Biocenter Oulu, in collaboration with researchers from Oulu University Hospital, Turku University and Kiel University, Germany.
The research was funded by the Academy of Finland, Pediatric Research Foundation, National Institutes of Health Foundation, State Research Funding, Finnish Cultural Foundation and Erjo Johansson Foundation.
The study was published The microbiome Journal: Kaisanlahti, A., Turunen, J., Byts, N. etc Maternal microbiota communicates with the fetus through microbiota-derived extracellular vesicles. The microbiome 11, 249 (2023).
Kaisanlati, A., etc. (2023). Maternal microbiota communicates with the fetus through microbiota-derived extracellular vesicles. The microbiome. doi.org/10.1186/s40168-023-01694-9.