Nodal is required to maintain the uterine environment in an anti-inflammatory state during pregnancy†

Preterm birth remains the major cause of perinatal mortality and morbidity worldwide, affecting up to 12% of pregnancies and accounting for ~75% of neonatal deaths. However, the mechanisms and causes that underlie it are still largely unknown. One of the major causes of preterm birth is infection or inflammation within the maternal-fetal interface. Our lab has previously shown that a uterine specific deletion of Nodal results in mutant females delivering 2 days prior to term demonstrating an important role for this factor in the maintenance of pregnancy. Here, we have addressed the function of Nodal in the uterus during pregnancy. We demonstrate that Nodal heterozygous mice have an increase in basal levels of pro-inflammatory cytokines IL-1β, IL-6, IL-12p, TNF-α, and IFN-γ as well as an increase in the number of macrophages in response to the inflammatory agent, lipopolysaccharide (LPS). Using bone marrow-derived macrophages, we demonstrated that pretreatment with recombinant Nodal reduces pro-inflammatory gene expression when these cells are challenged with LPS. Our results demonstrate that Nodal is required to maintain the uterine environment in an anti-inflammatory state by preventing proinflammatory cytokine expression.