CD19+CD5+ B-­1a B cells regulate T cell differentiation associated with pregnancy disturbances

DAMIÁN OSCAR MUZZIO; MAREK ZYGMUNT; FEDERICO JENSEN

Budapest

Congreso; 11th Congress of the European Society For Reproductive Immunology; 2014

Research Laboratory, Department of Obstetrics and Gynecology, University of Greifswald, Greifswald, Germany

Introduction: Pregnancy well-being relies on an adequate regulation between the pro-inflammatory and anti-inflammatory arms of the immune system. CD19+CD5+ B-1a B cells have been associated to pro-inflammatory pregnancy disorders like preeclampsia, through the se-cretion of AT1-AA. Besides, B-1a B cells have been shown to participate in the induc-tion of pro-inflammatory Th1 and Th17 T cells. Objective: To evaluate the role of CD19+CD5+ B-1a B cells in controlling Th1 and Th17 T cells dif-ferentiation during pregnancy using a mouse model of pregnancy disturbances. Methods: CD19+CD5+ cells were magnetically isolated from peritoneal cavity (PerC) of non-pregnant, BALB/c-mated (normal pregnant combination (NP)) or DBA/2J mated (abor-tion-prone combination (AP)) CBA/J females on day 14 of pregnancy. Isolated cells were inactivated with mitomycin-c and co-cultured (1:2) for 5 days with magnetically isolated allogeneic CD4+CD25- T cells. Some wells were treated with a Th17 differentia-tion cocktail (anti IFNγ, anti IL4, TGFβ, IL6 and IL23). Th1 and Th17 cytokines in super-natants was measured by CBA array system. Expression levels of B-1a B cell activation markers (MHCII, CD80, CD86, PDL1, PDL2 and FASL) were assessed in B-1a B cells from non-pregnant, NP and AP mice. Results: B-1a B cells from non-pregnant mice induced a modest production of IL17 by T cells that was boosted when T cells were co-cultured with B-1a B cells from AP mice. Nota-bly, B-1a B cells from NP mice strongly inhibited IL17 production by T cells, even in the presence of a Th17 induction cocktail. Similarly, Th1 cytokines (TNF, IFN, IL2 and MCP-1) were higher produced by T cells when co-cultured with B-1a B cells from AP mice as compared to those cultured with B-1a B cells from NP mice. B-1a B cell from NP mice expressed significantly lower levels of CD86 than B-1a B cells from AP or non-pregnant controls mice. Conclusion: We demonstrated in this work that B-1a B cells have a central role in regulating T cell differentiation associated with pregnancy disturbances. This unexplored role of B-1a B cells opens new alternatives to design strategies to control undesired immune activation affecting pregnancy outcome.