Developmental lineages and functions of macrophages in white adipose tissue

摘要：脂肪组织相关疾病，包括肥胖、脂肪代谢障碍和癌症相关脂肪 在美国，浪费总共占四分之一的死亡（1-3）。尽管数量惊人 在死亡病例中，治疗选择仍然有限且不令人满意。自20世纪90年代以来， 证实了脂肪组织中巨噬细胞的积累和激活与炎症有关， 胰岛素抵抗和2型糖尿病（4-20）。然而，组织外脂肪组织巨噬细胞的作用 炎症仍然知之甚少。这一点尤其重要，因为研究表明， 巨噬细胞可能参与脂肪发育（21-23）、脂肪储存（24）和防止脂肪消耗 （25）.我们在《科学》杂志上发表的初步数据（26）表明，胚胎来源的脂肪组织常驻 巨噬细胞通过产生PDGFa促进脂肪细胞中的脂质储存。该过程独立于 骨髓源性巨噬细胞促进的炎症和胰岛素抵抗。 我们在（目标1）中的初步数据表明，巨噬细胞是脂肪损失所必需的。因此，在目标1中，我将 描述负责的巨噬细胞谱系（K99）并识别巨噬细胞依赖性机制（R 00） 控制脂肪动员/损失。在（目标2）中，我将确定控制脂质储存的转录基础 通过脂肪组织驻留巨噬细胞使用单核RNA测序（K99）。我希望能推断出 细胞回路和下游信号通路的变化，控制脂肪储存。候选 在本研究的R 00阶段，将使用人类脂肪类器官和 体内小鼠模型。在（目标3）中，我将使用含有人类居民样巨噬细胞的人类脂肪类器官 以证实PDGFa在人类脂肪储存中的作用（K99）。我发现人类脂肪类器官含有 与巨噬细胞较少的脂肪类器官相比，Pdgfc+居民样巨噬细胞积累更多的脂质。我会 (R00)使用这些脂肪类器官来确定巨噬细胞如何影响脂质代谢， 巨噬细胞直接作用于脂肪细胞。此外，人类类器官将用于筛查巨噬细胞- 目的1和2中确定的能量储存的依赖性介质。我会继续接受弗雷德里克博士的指导 巨噬细胞生物学领域的领导者。 盖斯曼实验室是最早描述 巨噬细胞的发育谱系和功能。我也将受益于我的顾问的专业知识， 委员会成员包括安东尼·费兰特、克里斯·格拉斯和奥利维尔·埃尔门托。克里斯·格拉斯和奥利弗博士 Elemento是备受尊敬的科学家，在巨噬细胞和白色脂肪组织分析方面具有专业知识 通过单细胞方法学。鉴于安东尼·费兰特博士是骨髓细胞生物学领域的专家， 代谢和脂肪组织功能。我的期望是，这个建议结合我的专业知识， 药物开发将不仅提供脂肪组织巨噬细胞的全面功能视图， 有助于开发可控制肥胖、脂肪营养不良或恶病质患者肥胖的治疗方法。

ABSTRACT: Adipose tissue-associated disorders including obesity, lipodystrophy, and cancer-associated fat wasting collectively account for 1 in 4 deaths in the United States (1-3). Despite the devastatingly high number of deaths, therapeutic options remain limited and unsatisfactory. Landmark studies since the 1990’s have established that accumulation and activation of macrophages in adipose tissues are linked to inflammation, insulin resistance, and type 2 diabetes (4-20). However, the roles of adipose tissue macrophages outside tissue inflammation remain poorly understood. This is particularly important, as studies suggest that adipose tissue macrophages may be involved in fat development (21-23), fat storage (24), and protection against fat wasting (25). Our preliminary data published in Science (26) demonstrate that embryo-derived adipose tissue resident macrophages promote lipid storage in adipocytes via production of PDGFcc. This process is independent from inflammation and insulin resistance promoted by bone-marrow-derived macrophages. Our preliminary data in (Aim 1) suggest that macrophages are required for fat loss. Therefore, in Aim 1 I will delineate the responsible macrophage lineages (K99) and identify macrophage-dependent mechanisms (R00) that control fat mobilization/loss. In (Aim 2), I will determine the transcriptional basis for control of lipid storage by adipose tissue resident macrophages using single nucleus RNA-sequencing (K99). I expect to deduce changes in cellular circuitries and downstream signaling pathways that control fat storage. The candidate molecules identified here will be explored in the R00 phase of this research using human fat organoids and in vivo mouse models. In (Aim 3), I will use human fat organoids that contain human resident-like macrophages to confirm the role of PDGFcc in fat storage in humans (K99). I have found that human fat organoids that contain Pdgfc+ resident-like macrophages accumulate more lipids as compared to macrophage-less fat organoids. I will (R00) use these fat organoids to determine how macrophages affect lipid metabolism and identify whether macrophages act directly on adipocytes. Additionally, human organoids will be used to screen for macrophage- dependent mediators of energy storage identified in Aims 1 and 2. I will continue to be mentored by Dr Frederic Geissmann, a leader in the field of macrophage biology. The Geissmann lab is among the first to characterize the developmental lineages and functions of macrophages. I will also benefit from the expertise of my advisory committee that includes Anthony Ferrante, Chris Glass, and Olivier Elemento. Drs. Chris Glass and Olivier Elemento are highly respected scientists with expertise in analysis of macrophages and white adipose tissues by single cell methodologies. Whereas, Drs Anthony Ferrante is an expert in the areas of myeloid cell biology, metabolism, and adipose tissue function. My expectations are that this proposal combined with my expertise in drug development will not only provide a comprehensive functional view of adipose tissue macrophages but also aid in development of therapies that may control adiposity in obese, lipodystrophic, or cachectic patients.