MiR-150 regulated adiose tissue B cells in obesity

脂肪组织B细胞是脂肪组织中第二丰富的免疫细胞，在肥胖时它们占脂肪组织内基质细胞总数的20%以上。直到最近，临床前和临床研究才表明，脂肪组织B细胞可以调节脂肪组织的功能，并导致肥胖期间的代谢综合征。然而，我们对脂肪组织B细胞功能的分子机制的了解有限，这显著阻碍了靶向居住在脂肪组织中的B细胞来缓解肥胖引起的代谢性疾病的潜在翻译益处。我们项目的中心目标是确定这些B细胞在肥胖过程中的关键调节因素。然而，我们的新数据打开了一个新的干预点，通过包括miR-150的microRNAs的作用来控制这些促进炎症的B细胞的功能。我们的数据支持中心假设：在肥胖应激下，miR-150是脂肪组织B细胞激活的关键调节因子，miR-150的异常调节促进了脂肪组织B细胞的促炎反应，破坏了它们与脂肪组织生态位中其他细胞相互作用的能力，从而导致脂肪组织炎症和胰岛素抵抗的加剧。我们将首先演示miR-150如何调节正常的B细胞功能，从而在三个特定的目标上对这一假说进行批判性检验。这将通过创造新的和未发表的小鼠品系来实现，这些品系将允许精细控制B细胞在不同发育阶段的miR-150作用。具体地说，我们将利用我们的新型miR-150 B细胞特异性敲除和过表达小鼠来定义脂肪组织B细胞在瘦和肥胖条件下的功能。在第二个目标中，我们将确定miR-150的基因靶点在控制脂肪组织B细胞行为和功能中的调节作用。具体地说，miR-150通过特定的靶基因来调节B细胞的通路，我们已经筛选了30多个预测基因，并成功地鉴定了几个B细胞特异性的miR-150靶点。我们将利用异位表达和shRNA敲除来确定它们在miR-150介导的ATB激活和随后的肥胖脂肪组织体内功能中的作用。在目标3中，我们将测试假设，即在脂肪组织B细胞中miR-150的破坏干扰了它们控制细胞间相互作用的能力。我们将确定miR-150在与其他细胞群体的串扰过程中的机制调节，包括来自脂肪组织的T细胞和巨噬细胞以及脂肪细胞本身。我们推测，促炎症B细胞使用的部分机制是通过MHC II途径，该途径将在不同的生理条件下进行测试。总之，这三个目标将阐明microRNA调节的脂肪组织B细胞的关键调控机制，以及它们在协调脂肪组织对肥胖的代谢/免疫反应中的作用。

Adipose tissue B cells are the second most abundant immune cells found in adipose tissue, and they account for more than 20% of the stromal population within adipose tissue during obesity. Pre-clinical and clinical studies have only recently suggested that adipose tissue B cells can modulate adipose tissue function and contribute to the metabolic syndromes suffered during obesity. However, our understanding of the molecular mechanisms underlying adipose tissue B cell function is limited, and this has significantly hampered the potential translational benefit of targeting B cells that dwell in adipose tissue to mitigate obesity induced metabolic disease. The central goal of our project is to define the key regulators for these B cells during obesity. Nevertheless, our new data has opened a novel point of intervention to control the function of these inflammation-promoting B cells through the action of microRNAs that include miR-150. Our data support the central hypothesis suggesting that: Under the stress of obesity, miR-150 is a key regulator of adipose tissue B cell activation where dysregulation of miR-150 facilitates the pro-inflammatory response of adipose tissue B cells and corrupts their ability to interact with other cells in the adipose tissue niche, which results in exacerbated adipose tissue inflammation and insulin resistance. We will critically test this hypothesis in three specific aims by first demonstrating how miR-150 regulates normal B cell function. This will be achieved with the creation of new and unpublished mouse strains that will allow exquisite control of miR-150 action in B cells during different stages of development. Specifically, we will utilize our novel miR-150 B-cell specific knockout and overexpression mice to define how adipose tissue B cells function under lean and obese conditions. In the second aim we will determine the regulatory role of the gene targets of miR-150 in controlling adipose tissue B cell behavior and function. Specifically, miR-150 regulates B cell pathways through specific target genes and we have screened more than 30 predicted genes and successfully identified several B cell specific miR-150 targets. We will utilize ectopic expression and shRNA knockdown to determine their roles in miR-150-mediated ATB activation and subsequent in vivo function in obese adipose tissue. In aim 3 we will test the hypothesis that disruption of miR-150 in adipose tissue B cells interferes with their ability to control cell-to-cell interactions. We will determine the mechanistic regulation of miR-150 during crosstalk with other cell populations including T cells and macrophages derived from adipose tissue and also adipocytes themselves. We have postulated that part of the mechanism used by the pro-inflammatory B cells is through the MHC II pathway, which will be tested under various physiological conditions. Collectively, these three aims will elucidate the critical regulatory mechanism of microRNA-regulated adipose tissue B cells and their contribution in orchestrating the adipose tissue metabolic/immunologic response to obesity.