The Impact of Maternal Western Style Diet on Immune Cell Function and Development of Non-Alcoholic Fatty Liver Disease

摘要/项目摘要 非酒精性脂肪性肝病（NAFLD）是目前世界上最常见的慢性肝病。然而，在这方面， 其病理生理学尚未解决，缺乏治疗选择。不良的母亲饮食和肥胖会促进 NAFLD在后代，但这种情况发生的机制尚不清楚。我们建议确定 母体西式饮食（WSD）对非人灵长类动物后代免疫细胞和肝脏表型的影响 (NHP)具有与人类儿科NAFLD相似特征的模型。虽然NAFLD的病理生理学是 多因素、促炎性巨噬细胞（Mφ）活化和骨髓单核细胞向 肝脏对其进展至关重要。先天免疫系统来源于造血干细胞（HSC）， 主要存在于骨髓中。母亲的饮食已被证明会扭曲HSC功能， 表现为Mφ发育和活性的改变，可能促进NAFLD进展。我们发现 在我们的NHP模型中，母体WSD增加了胎儿脂肪变性（肝脏脂肪），减少了骨髓增殖， 细胞，并导致骨髓（先天免疫）细胞产生的比例增加。引人注目的是，这些表型 也存在于暴露于母体WSD，然后在剩余时间内以健康饮食断奶的青少年NHP中 生命此外，我们还观察到暴露于母体WSD的NHP胎儿Mφ细胞因子反应失调。 最后，缺氧诱导因子（HIF）-1a已成为Mφ促炎表型的关键驱动因素。 我们在小鼠中的初步数据显示，喂食WSD的小鼠肝脏Mφ HIF 1A RNA表达增加， HIF-1a蛋白的稳定化已显示促进小鼠中的Mφ炎症和纤维化。这表明 抑制骨髓中的HIF 1a可以防止NAFLD中的炎性Mφ活性。因此，目前的数据 支持了新的假设，即母体WSD在子宫内差异性地编程HSC，以促进 持续性骨髓细胞偏斜和下游Mφ功能障碍，最终导致肝损伤， Hif 1a是这种Mφ功能障碍所必需的。为了研究这个假设，我们 建议：1）我们将在胎儿和幼年NHP的肝脏中利用qPCR和显微镜技术， 确定母体WSD对纤维化、组织炎症和脂质含量的影响。我们亦会研究 转录表型和肝脏中招募与常驻Mφ的比例，以确定相对的 这些细胞在促进NAFLD中的作用。2)确定母体WSD如何改变转录途径 在NHP后代中负责HSC发育、增殖和Mφ表型变化的HSC中，包括 Mφ细胞因子应答。3)我们将测试小鼠造血细胞中Hif 1a的缺失是否是 母体WSD诱导促炎性肝Mφ反应和纤维化的改变。这些研究将使 描述性和机械性的洞察母亲WSD如何影响后代NAFLD，这可能会导致新的 治疗方法来阻止NAFLD进展或减轻这种流行疾病的影响。

Abstract/Project Summary Non-alcoholic fatty liver disease (NAFLD) is now the most common chronic liver disease worldwide. However, its pathophysiology is unresolved and treatment options are lacking. Poor maternal diet and obesity promote NAFLD in offspring, but the mechanisms by which this occurs are not clear. We propose to identify the impact of maternal western style diet (WSD) on offspring immune cell and liver phenotypes in a non-human primate (NHP) model with features similar to human pediatric NAFLD. While the pathophysiology of NAFLD is multifactorial, pro-inflammatory macrophage (Mφ) activation and recruitment of bone marrow monocytes to the liver are critical for its progression. The innate immune system is derived from hematopoietic stem cells (HSCs), which reside primarily in the bone marrow. Maternal diet has been shown to skew HSC function, which may manifest as alterations in Mφ development and activity, potentially promoting NAFLD progression. We find that maternal WSD in our NHP model increases fetal steatosis (liver fat), decreases proliferation of bone marrow cells and causes a proportional increase in myeloid (innate immune) cell production. Strikingly, these phenotypes are also present in juvenile NHP exposed to maternal WSD then weaned onto a healthy diet for the remainder of life. In addition, we observe dysregulated Mφ cytokine response in NHP fetuses exposed to maternal WSD. Finally, hypoxia-inducible factor (HIF)-1a has emerged as a critical driver of the Mφ pro-inflammatory phenotype. Our preliminary data in mice show that mice fed a WSD have increased hepatic Mφ HIF1A RNA expression and HIF-1a protein stabilization has been shown to promote Mφ inflammation and fibrosis in mice. This suggests that inhibiting HIF1a in bone marrow may prevent inflammatory Mφ activity in NAFLD. Therefore, current data supports the novel hypothesis that maternal WSD differentially programs HSCs in utero to promote persistent myeloid cell skewing and downstream Mφ dysfunction that ultimately drives liver damage and fibrosis later in life, and that Hif1a is necessary for this Mφ dysfunction. To investigate this hypothesis we propose to: 1) We will utilize qPCR and microscopic techniques in livers from fetal and juvenile NHPs to determine the impact of maternal WSD on fibrosis, tissue inflammation and lipid content. We will also investigate the transcriptional phenotypes and proportions of recruited vs. resident Mφ in livers, to determine the relative contributions of these cells in promoting NAFLD. 2) Identify how maternal WSD alters transcriptional pathways in HSCs responsible for shifts in HSC development, proliferation, and Mφ phenotypes in NHP offspring, including Mφ cytokine response. 3) We will test whether deletion of Hif1a in hematopoietic cells in mice is necessary for maternal WSD induced alterations in pro-inflammatory hepatic Mφ response and fibrosis. These studies will give descriptive and mechanistic insight into how maternal WSD impacts offspring NAFLD, which may lead to new therapeutic approaches to hinder NAFLD progression or attenuate the impact of this prevalent disease.