Characterization of murine amniotic fluid B cells in normal pregnancy and in preterm birth

• Published in: Reproduction (Cambridge, England) Vol. 158; no. 4; pp. 369 - 376
• Main Authors: Bommer, Imke, Juriol, Lorena, Muzzio, Damián, Valeff, Natalin, Ehrhardt, Jens, Matzner, Franziska, Ziegler, Katharina, Malinowsky, Kristin, Ventimiglia, María Silvia, Zygmunt, Marek, Jensen, Federico
• Format: Journal Article
• Language: English
• Published: England Bioscientifica Ltd 01-10-2019
• ISSN: 1470-1626; 1741-7899
• DOI: 10.1530/REP-19-0150

The amniotic fluid provides mechanical protection and immune defense against pathogens to the fetus. Indeed, components of the innate and adaptive immunity, including B cells, have been described in the amniotic fluid. However, limited information concerning phenotype and functionality of amniotic fluid B cells is available. Hence, we aimed to perform a full phenotypical and functional characterization of amniotic fluid B cells in normal pregnancy and in a mouse model of preterm birth. Phenotypic analysis depicted the presence of two populations of amniotic fluid B cells: an immature population, resembling B1 progenitor cells and a more mature population. Further isolation and in vitro co-culture with a bone marrow stroma cell line demonstrated the capacity of the immature B cells to mature. This was further supported by spontaneous production of IgM, a feature of the B1 B cell sub-population. An additional in vitro stimulation with lipopolysaccharide induced the activation of amniotic fluid B cells as well as the production of pro and anti-inflammatory cytokines. Furthermore, amniotic fluid B cells were expanded in the acute phase of LPS-induced preterm birth. Overall our data add new insight not only on the phenotype and developmental stage of the amniotic fluid B1 B cells but especially on their functionality. This provides important information for a better understanding of their role within the amniotic fluid as immunological protective barrier, especially with regard to intraamniotic infection and preterm birth.