Maternal Obesity and Pediatric NAFLD: Fetal Origins and Long-term outcomes in Non Human Primates

项目摘要 在美国，母亲超重和肥胖的患病率持续增加， 年龄、种族和民族以及社会经济地位的范围。令人担忧的是，十分之一的婴儿和幼儿 肥胖，五分之一的年轻人既肥胖又有儿童非酒精性脂肪性肝病（NAFLD）的风险。 NAFLD可以在子宫内开始，纵向研究显示， 肥胖的母亲NAFLD的一些特征在儿童和成人中是相似的，但门静脉纤维化和炎症 在儿童NASH患者中比成人患者更常见，并预示着快速进展至终末期 肝脏疾病在成年早期的原因仍然知之甚少。我们的团队在过去的十年里 开发和表征复杂的非人灵长类动物（NHP）高脂肪/热量密度模型 母亲的饮食消费与人类具有至关重要的发育和生理相似性。 来自我们的良好表征的NHP模型的数据表明，母体西式饮食（MWSD） 门静脉三联体中的胎肝胶原沉积和3岁时持续存在的星状细胞活化（3 YO） 幼年动物，尽管切换到健康的食物饮食断奶。值得注意的是，2个在细胞凋亡中起关键作用的miRNAs， 肝脏代谢和炎症反应显著增加（miR-122）或减少（miR-34 a）， 当肥胖母亲转为健康饮食时，胎儿肝脏部分正常化。我们的研究结果表明 这些miRNA是饮食敏感的，并且是生命早期NAFLD的表观遗传引发的候选靶标。我们 在3岁NHP后代中的初步数据也显示MWSD重新编程造血干细胞祖细胞， （HSPC）和骨髓源性巨噬细胞（BMDM）对糖酵解表型的反应减弱， IL-4，提示抗炎能力降低，Mφ承担修复性炎症的能力受损。 表型。考虑到M2样Mφ在肝损伤愈合中的重要性，我们的总体假设是MWSD改变了肝损伤的发生。 出生前肝脏中的miRNA与表观遗传重编程的HSPC和肝脏Mφ平行。这导致 持续产生高炎症性Mφ，并且在整个生命周期内无法解决肝损伤。的 这项建议的首要目标是了解MWSD驱动表观遗传的机制基础 重塑和NAFLD的发病机制在子宫内开始。在此修订申请中，我们的目的是：1） 检验MWSD改变胎儿miR-34 a和miR-122与胎儿肝脏中特异性靶点结合的假设， 使用单细胞RNAseq鉴定幼年肝脏中的巨噬细胞亚组; 2）测试MWSD 在分离的胎儿和3 YO HSPC和肝脏Mφ中通过不同的转录驱动促炎功能 和表观遗传机制。3)检验MWSD破坏MWSD中BA信号传导和HNF 4 α的假设 肝细胞，并优先影响胎儿和出生后肝脏中的门静脉周围肝细胞。 胎儿和青少年NHP，具有与人类相似的发育特征，我们将破译MWSD如何 暴露触发HSPC和肝脏Mφ中的表观遗传和炎症修饰，驱动新途径 潜在的儿科NAFLD。

PROJECT SUMMARY The prevalence of maternal overweight and obesity continues to increase in the U.S. and spans the spectrum of age, race and ethnicity, and socioeconomic status. Alarmingly, 1 in 10 infants and toddlers are obese, and 1 in 5 youth are both obese and at-risk for pediatric Non-alcoholic fatty liver disease (NAFLD). NAFLD can begin in utero with longitudinal studies showing an increased risk of NAFLD in adolescents born to obese mothers. Some features of NAFLD are similar in children and adults, yet portal fibrosis and inflammation are more common in pediatric NASH patients than adult patients, and portends a rapid progression to end-stage liver disease in early adulthood for reasons that remain poorly understood. Our group has spent the past decade developing and characterizing a sophisticated nonhuman primate (NHP) model of high fat/calorically dense maternal diet consumption that has critically important developmental and physiological similarities to humans. Data from our well-characterized NHP model demonstrate that maternal Western-style diet (MWSD) triggers fetal hepatic collagen deposition in the portal triad and stellate cell activation that persists in 3-year-old (3YO) juvenile animals, despite switching to a healthy chow diet at weaning. Notably, 2 miRNAs with critical roles in liver metabolism and inflammatory responses were significantly increased (miR-122) or decreased (miR-34a) in fetal liver and partially normalized when obese mothers were switched to a healthy chow diet. Our results suggest these miRNAs are diet-sensitive and candidate targets for epigenetic priming of NAFLD early in life. Our preliminary data in 3YO NHP offspring also show that MWSD reprograms hematopoietic stem cell progenitors (HSPC)s and bone marrow derived macrophages (BMDM) to a glycolytic phenotype and a blunted response to IL-4, suggesting decreased anti-inflammatory capacity and impaired Mφ ability to assume a reparative phenotype. Given the importance of M2-like Mφ for healing liver injury,our overall hypothesis is that MWSD alters miRNAs in liver in parallel with epigenetically reprogrammed HSPC and liver Mφ before birth. This leads to ongoing production of hyper-inflammatory Mφ and the inability to resolve liver injury across the lifespan. The overarching goal of this proposal is to understand the mechanistic basis by which MWSD drives epigenetic remodeling and the pathogenesis for NAFLD beginning in utero. In this revised application, our Aims are to: 1) Test the hypothesis that MWSD alters binding of fetal miR-34a, and miR-122 to specific targets in fetal liver, and identify macrophage sub-sets in Juvenile livers using single cell RNAseq; 2) Test the hypothesis that MWSD drives pro-inflammatory functions in isolated fetal and 3YO HSPC and liver Mφ through distinct transcriptional and epigenetic mechanisms. 3) Test the hypothesis that MWSD disrupts BA signaling and HNF4α in MWSD hepatocytes and preferentially affects periportal hepatocytes in fetal and post-natal livers.Taken together, using fetal and Juvenile NHP, which have developmental features similar to humans, we will decipher how MWSD exposure triggers epigenetic and inflammatory modifications in HSPC and liver Mφ that drive novel pathways underlying pediatric NAFLD.