Table1_c-Myc Drives inflammation of the maternal-fetal interface, and neonatal lung remodeling induced by intra-amniotic inflammation.DOCX

Background: Intra-amniotic inflammation (IAI) is associated with increased risk of preterm birth and bronchopulmonary dysplasia (BPD), but the mechanisms by which IAI leads to preterm birth and BPD are poorly understood, and there are no effective therapies for preterm birth and BPD. The transcription factor c-Myc regulates various biological processes like cell growth, apoptosis, and inflammation. We hypothesized that c-Myc modulates inflammation at the maternal-fetal interface, and neonatal lung remodeling. The objectives of our study were 1) to determine the kinetics of c-Myc in the placenta, fetal membranes and neonatal lungs exposed to IAI, and 2) to determine the role of c-Myc in modulating inflammation at the maternal-fetal interface, and neonatal lung remodeling induced by IAI.
Methods: Pregnant Sprague-Dawley rats were randomized into three groups: 1) Intra-amniotic saline injections only (control), 2) Intra-amniotic lipopolysaccharide (LPS) injections only, and 3) Intra-amniotic LPS injections with c-Myc inhibitor 10058-F4. c-Myc expression, markers of inflammation, angiogenesis, immunohistochemistry, and transcriptomic analyses were performed on placenta and fetal membranes, and neonatal lungs to determine kinetics of c-Myc expression in response to IAI, and effects of prenatal systemic c-Myc inhibition on lung remodeling at postnatal day 14.
Results: c-Myc was upregulated in the placenta, fetal membranes, and neonatal lungs exposed to IAI. IAI caused neutrophil infiltration and neutrophil extracellular trap (NET) formation in the placenta and fetal membranes, and neonatal lung remodeling with pulmonary hypertension consistent with a BPD phenotype. Prenatal inhibition of c-Myc with 10058-F4 in IAI decreased neutrophil infiltration and NET formation, and improved neonatal lung remodeling induced by LPS, with improved alveolarization, increased angiogenesis, and decreased pulmonary vascular remodeling.
Discussion: In a rat model of IAI, c-Myc regulates neutrophil recruitment and NET formation in the placenta and fetal membranes. c-Myc also participates in neonatal lung remodeling induced by IAI. Further studies are needed to investigate c-Myc as a potential therapeutic target for IAI and IAI-associated BPD.

研究背景：宫内炎症（Intra-amniotic inflammation, IAI）与早产及支气管肺发育不良（bronchopulmonary dysplasia, BPD）风险升高密切相关，但IAI诱发早产与BPD的具体分子机制尚未明确，且目前尚无针对早产及BPD的有效治疗手段。转录因子c-Myc可调控细胞增殖、凋亡及炎症反应等多种生物学过程。本研究推测c-Myc可调控母胎界面炎症反应与新生鼠肺重塑。本研究的目的包括：1）明确IAI暴露下胎盘、胎膜及新生鼠肺组织中c-Myc的动态表达变化；2）阐明c-Myc在调控IAI诱导的母胎界面炎症反应及新生鼠肺重塑中的作用。

研究方法：将妊娠Sprague-Dawley（SD）大鼠随机分为三组：1）仅宫内注射生理盐水（对照组）；2）仅宫内注射脂多糖（lipopolysaccharide, LPS）；3）宫内注射LPS联合c-Myc抑制剂10058-F4。对胎盘、胎膜及新生鼠肺组织进行c-Myc表达检测、炎症标志物与血管生成标志物分析、免疫组织化学染色及转录组测序分析，以明确IAI诱导下c-Myc的表达动态，并探究产前全身性c-Myc抑制对出生后第14天新生鼠肺重塑的影响。

研究结果：IAI暴露后，胎盘、胎膜及新生鼠肺组织中c-Myc的表达均显著上调。IAI可诱发胎盘与胎膜出现中性粒细胞浸润及中性粒细胞胞外陷阱（neutrophil extracellular trap, NET）形成，同时诱导新生鼠肺重塑并出现符合BPD表型的肺动脉高压表现。在IAI模型中，使用10058-F4抑制c-Myc可减少中性粒细胞浸润与NET形成，改善LPS诱导的新生鼠肺重塑，具体表现为肺泡形成增加、血管生成增强及肺血管重塑减轻。

讨论：在IAI大鼠模型中，c-Myc可调控胎盘与胎膜内的中性粒细胞募集及NET形成。此外，c-Myc亦参与IAI诱导的新生鼠肺重塑过程。后续需开展进一步研究以探讨c-Myc作为IAI及IAI相关性BPD潜在治疗靶点的可行性。