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)是目前全球最常见的慢性肝病。然而， 它的病理生理学尚未解决，治疗方案也缺乏。不良的母亲饮食和肥胖会促进 NAFLD在后代中存在，但其发生机制尚不清楚。我们建议确定影响 母体西式饮食(WSD)对子代免疫细胞和非人灵长类动物肝脏表型的影响 (NHP)模型，其特征类似于人类NAFLD。而NAFLD的病理生理学是 多因素、促炎巨噬细胞(Mφ)的激活和骨髓单核细胞的募集 肝脏是其进展的关键。先天免疫系统来源于造血干细胞， 它们主要存在于骨髓中。母亲的饮食已被证明扭曲了HSC的功能，这可能 表现为Mφ发育和活动的改变，可能促进非酒精性脂肪肝的进展。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)，减少了骨髓的增殖 并导致髓系(先天免疫)细胞产生成比例的增加。引人注目的是，这些表型 在暴露于母体WSD的幼年NHP中也存在，然后在其余时间断奶以健康饮食 生活的一部分。此外，我们还观察到暴露于母体水肿病的非高血压胎儿的M-φ细胞因子反应异常。 最后，低氧诱导因子-1a已成为M-φ促炎表型的关键驱动因素。 我们在小鼠中的初步数据显示，喂食五味子汤的小鼠肝MφHIF1aRNA表达增加， HIF-1a蛋白的稳定性已被证明可以促进M-φ小鼠的炎症和纤维化。这表明 抑制骨髓中HIF1a的表达可抑制非酒精性脂肪肝的炎性M-φ活性。因此，当前数据 支持一种新的假设，即母体WSD对子宫内的HSCs进行差异化编程以促进 持续性髓系细胞扭曲和下游Mφ功能障碍，最终导致肝脏损害和 在以后的生活中，HIF1a是Mφ功能障碍所必需的。为了研究这一假设，我们 建议：1)我们将在胎儿和幼年NHP的肝脏中利用qPCR和显微技术来 确定母体WSD对肝纤维化、组织炎症和脂质含量的影响。我们还将调查 确定M-φ在肝脏中的转录表型和比例 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 NHP子代中负责HSC发育、增殖和Mφ表型转变的HSC，包括 Mφ细胞因子应答。3)我们将测试是否有必要删除小鼠造血细胞中的HIF1a 母体水煎剂诱导的促炎性肝M-φ反应和纤维化的改变。这些研究将给出 对母亲WSD如何影响后代NAFLD的描述性和机械性洞察，这可能导致新的 阻止NAFLD进展或减轻这种流行疾病影响的治疗方法。

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.