CXCL12 regulation of placental development and fetal health

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Project Summary/Abstract Impaired placental function leads to dangerous pregnancy complications such as preeclampsia, intrauterine growth restriction, placental abruption, and stillbirth. Placental dysfunction is the leading cause of maternal, fetal, and neonatal morbidity and mortality worldwide and predisposes offspring to higher risks of developing cardiovascular disease, type 2 diabetes, insulin resistance, obesity, hypertension, and stroke during adulthood. To improve human health, it is imperative to elucidate the mechanisms causing impaired placental development. The chemokine, CXCL12 (L12) regulates several processes central to the development of the placenta (placentation) such as stimulating cell proliferation and migration, vascularization, immune cell recruitment and cytokine production through direct actions on fetal trophoblast and maternal endometrial and immune cells. These essential functions are elicited via L12 activating its two receptors, CXCR4 (R4) and/or CXCR7 (R7); however, the contributions of R4 compared to R7 during placentation remain unclear, denoting a substantial gap in knowledge. Our group and others demonstrated L12-mediated signaling is strongly implicated in placental dysfunction and specifically preeclampsia etiology. Defining L12-induced actions through its two receptors may reveal underlying mechanisms causing placental dysfunction. We developed an innovative animal model to study L12-dependent signaling at the fetal (trophoblast)-maternal (endometrial) interface by delivering treatments directly into the uterus. Our published and preliminary data demonstrate disrupting L12-mediated signaling during the small window of embryo implantation diminishes placental vascularization, induces autophagy, and creates an excessive inflammatory placental environment later in gestation. Notably, several observed outcomes mirror those of placental dysfunction, suggesting an imbalance in L12/R4/R7 signaling may be causative. Preliminary data indicate transitory suppression of L12/R4 signaling induces lasting placental insufficiency with preeclampsia markers VEGF receptor-1 (sFLT-1) and placental growth factor (PlGF) remaining elevated months later, at midgestation. Whether excessive R7 activation contributes to these findings when R4 is suppressed remains uncertain. Our data underscore the importance of L12 during placentation and provide strong evidence that altering L12-mediated signaling induces enduring placental effects manifesting later in gestation. Nevertheless, we lack a clear understanding of how L12, excreted by fetal trophoblast cells, signals through R4 and R7 on trophoblast and maternal cells. This SC1 will test the overall hypothesize that L12 induces distinct biological responses through R4 versus R7, thereby differentially impacting placental development, function, and fetal growth. Results from Aim 1 will provide new scientific knowledge on R4 and R7 functions in placental biology during times impractical to obtain in humans through characterizing a robust in vivo model and placental phenotype at select gestational times. Mechanistic in vitro studies in Aim 2 will delineate L12-mediated signaling in fetal and maternal cells.