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

项目总结 在美国，母亲超重和肥胖的流行率继续上升，并横跨 年龄、种族和民族以及社会经济地位的范围。令人担忧的是，十分之一的婴儿和学步儿童 1/5的青少年肥胖且有患儿科非酒精性脂肪性肝病的风险。 NAFLD可以在子宫内开始，纵向研究表明出生在以下年龄的青少年患NAFLD的风险增加 肥胖的母亲。儿童和成人NAFLD的一些特征相似，但门脉纤维化和炎症 在儿童NASH患者中比成人患者更常见，并预示着快速进展到终末期。 成年期早期的肝病，其原因尚不清楚。我们的团队在过去的十年里 复杂的非人灵长类(NHP)高脂肪/高热量模型的建立和表征 母亲的饮食消费与人类在发育和生理上有着极其重要的相似之处。 来自我们特征良好的NHP模型的数据表明，母亲的西式饮食(MWSD)会触发 门静脉三联征中胎肝胶原沉积和星状细胞激活在3岁时持续(3YO) 幼年动物，尽管在断奶时转向健康的食物饮食。值得注意的是，2个miRNAs在 肝脏代谢和炎症反应显著增加(miR-122)或降低(miR-34a) 当肥胖的母亲转向健康的饮食时，胎儿肝脏和部分正常化。我们的结果表明 这些miRNAs是饮食敏感的，是NAFLD早期表观遗传启动的候选靶点。我们的 3YO NHP子代的初步数据也表明，MWSD对造血祖细胞进行再编程 S和骨髓源性巨噬细胞对糖酵解表型和钝化反应的反应 IL-4，提示抗炎能力下降，Mφ承担修复能力受损 表型。鉴于M2样Mφ对于修复肝损伤的重要性，我们的总体假设是MWSD改变 在出生前，肝脏中的φ与表观遗传重编程的HSPC和肝脏M miRNA平行。这导致了 持续产生高炎性M-φ，终生无法解决肝脏损伤。这个 这项建议的首要目标是了解MWSD驱动表观遗传的机制基础 非酒精性脂肪肝发生于宫内的重塑及其发病机制。在本修订申请中，我们的目标是：1) 测试MWSD改变胎儿miR-34a和miR-122与胎儿肝脏特定靶点结合的假设，以及 用单细胞RNAseq鉴定幼肝巨噬细胞亚群；2)检验MWSD的假设 在分离的胎儿和3YO 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)验证MWSD干扰BA信号和HNF4α的假说 肝细胞，并优先影响胎儿和出生后肝脏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是如何 暴露触发HSPC和肝脏Mφ的表观遗传和炎症修饰，从而驱动新的途径 潜在的儿童非酒精性脂肪肝。

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.