背景:小鼠中母体炎症的诱导导致被认为是IL-6依赖性的胎儿损伤。胎儿炎症反应,由胎儿或羊水IL-6升高定义,已被描述为后续胎儿损伤的潜在机制。母体IL-6产生和信号传导在胎儿IL-6反应中的作用目前尚不清楚。
方法:使用遗传和抗IL-6抗体策略来系统地阻断炎症期间的母体IL-6反应。在妊娠中期(E14.5)和妊娠晚期(E18.5)使用腹膜内注射脂多糖(LPS)诱导绒毛膜羊膜炎。该模型用于怀孕的C57Bl/6水坝,IL6-/-水坝,用抗IL-6(阻断经典和反式信号传导)或抗gp130抗体(仅阻断反式信号传导)和IL6+/-水坝处理的C57Bl/6水坝。注射LPS后六小时,母体血清,胎盘组织,收集羊水和胎儿组织或血清。基于珠子的多重测定用于评估IL-6,KC,IL-1β,TNF,IL-10,IL-22,IFN-γ,IL-13和IL-17A。
结果:C57Bl/6大坝的绒毛膜羊膜炎的特征是在妊娠中期母体血清IL-6,KC和IL-22水平升高,产仔数减少。C57Bl/6小鼠中胎儿对母体炎症的反应主要表现为胎盘中IL-6、KC和IL-22水平升高,妊娠中期和晚期的羊水和胎儿。全球IL-6基因敲除(IL6-/-)根除了母体,胎盘,羊水和胎儿IL-6对LPS的反应在中期和晚期妊娠和提高产仔存活率,而对KC或IL-22反应的影响最小。在LPS暴露时阻断C57Bl/6大坝中的母体经典IL-6信号传导减少了母体,胎盘,妊娠中期和晚期羊水和胎儿IL-6反应,而阻断母体IL-6反式信号仅影响胎儿IL-6表达。为了评估母体IL-6是否穿过胎盘并到达胎儿,在绒毛膜羊膜炎模型中使用IL-6+/-大坝。IL-6+/-大坝在注射LPS后引发全身炎症反应,以IL-6、KC和IL-22升高为特征。与IL-6+/-同窝对照相比,IL6+/-大坝出生的IL-6-/-幼崽的羊水IL-6水平降低,胎儿IL-6水平检测不到。
结论:胎儿对母体全身性炎症的反应依赖于母体IL-6信号传导,但是母体IL-6不能穿过胎盘并以可检测的水平到达胎儿。
The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.
Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6,
KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.
Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6,
KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6,
KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the
KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6+/- dams were utilized in the chorioamnionitis model. IL-6+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6,
KC and IL-22. IL-6-/- pups born to IL6+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6+/+ littermate controls.
The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.