The comparison of the immunological state of pregnancy to an immunosuppressed host-graft model continues to lead research and clinical practice to ill-defined approaches. This Review discusses recent evidence that supports the idea that immunological responses at the receptive maternal-fetal interface are not simply suppressed but are instead highly dynamic. We discuss the crucial role of trophoblast cells in shaping not only the way in which immune cells respond to the invading blastocyst but also how they collectively react to external stimuli. We also discuss the role of the microbiota in promoting a tolerogenic maternal immune system and highlight how subclinical viral infections can disrupt this status quo, leading to pregnancy complications.

Objective-To study whether an injury-induced inflammation might be the mechanism underlying the favorable effect of endometrial biopsy on the implantation rate in in vitro fertilization (IVF) patients. Design-Controlled clinical study.Setting-A medical center IVF unit and a research institute. Patient(s)-Women undergoing IVF who had previous failed treatment cycles.Intervention(s)-Endometrial samples were collected from two groups of patients on day 21 of their spontaneous menstrual cycle. The experimental, but not the control group underwent prior biopsy treatment on days 8 or/and 11 to 13 of that same cycle.Main Outcome Measure(s)-Abundance of immune cells, cytokines/chemokines level, correlation between these parameters and pregnancy outcome.Result(s)-A statistically significantly higher amount of macrophages/dendritic cells (HLA-DR + CD11c + cells) and elevated proinflammatory cytokines, tumor necrosis factor-α (TNF-α), growthregulated oncogene-α (GRO-α), interleukin-15 (IL-15), and macrophage inflammatory protein 1B (MIP-1B), were detected in day-21 endome-trial samples of the experimental group. A direct stimulatory effect of TNF-α on MIP-1B, GRO-α, and IL-15 messenger RNA (mRNA) expression was demonstrated. A positive correlation was found between the levels of macrophages/dendritic cells, MIP-1B expression, and TNF-α expression and the pregnancy outcome. Conclusion(s)-A biopsy-induced inflammatory response may facilitate the preparation of the endometrium for implantation. Increased MIP-1B expression could possibly serve for prediction of implantation competence.

Progress in our understanding of the role of the maternal immune system during healthy pregnancy will help us better understand the role of the immune system in adverse pregnancy outcomes. In this review, we discuss our present understanding of the 'immunity of pregnancy' in the context of the response to cervical and placental infections and how these responses affect both the mother and the fetus. We discuss novel and challenging concepts that help explain the immunological aspects of pregnancy and how the mother and fetus respond to infection.

Material Supplementary 9.DC1http://www.jimmunol.org/content/suppl/2010/06/16/jimmunol.100028

The results of this study suggest that trophoblast cells are able to recruit and successfully educate monocytes to produce and secrete a pro-inflammatory cytokine and chemokine profile supporting its growth and survival. Furthermore we demonstrate that trophoblast cells can modulate monocytes response to bacterial stimuli.