Metabolic Impacts of Type II Interferon Signals in Obesity

摘要 肥胖与脂肪组织中的促炎表型和之前的胰岛素抵抗相一致 2型糖尿病尽管有大量的证据，肥胖引起的炎症和肥胖之间的因果关系仍然存在。 胰岛素抵抗仍然未知。在上一个资助周期中，我们探讨了炎症如何使肥胖脱钩 胰岛素抵抗我们发现阻断干扰素γ（IFN γ）激活转录因子STAT1， 限制促炎程序，否则会限制白色脂肪组织（WAT）扩张， 降低胰岛素敏感性。我们还证明了IFN γ活性的完全消除介导了许多不良反应， 高脂肪饮食的影响，包括体重增加、线粒体功能减弱和胰岛素抵抗。多 包括我们自己的研究在内的研究观察到，糖尿病小鼠和人类的WAT中STAT1表达较高，这表明 IFN γ活性可能仍然代表慢性肥胖的致病结果。本周期的目标 是填补我们对IFN γ传递信号的基本方式的机械理解中的重要空白， 脂肪细胞中的代谢和胰岛素敏感性的转录调节。为了实现我们的目标，我们将 证明WAT中的IFN γ受体启动营养过剩的代谢减少（目的1）， 建立抑制脂肪细胞中细胞能量平衡的IFN γ下游转录结果 (Aim 2）。最后，我们将确定肥胖相关的炎症是否限制了一种新的途径， 支持维持WAT扩增所必需的脂肪生成反应（Aim 3）。最终，这些知识将 教我们如何利用免疫系统来治疗肥胖及其并发症。

ABSTRACT Obesity coincides with pro-inflammatory phenotypes in adipose tissues and the insulin resistance that precedes type 2 diabetes. Despite a wealth of evidence, causal relationships between obesity-induced inflammation and insulin resistance remain unknown. In the last grant cycle, we explored how inflammation uncouples obesity from insulin resistance. We showed blocking interferon gamma (IFN) activation of the transcription factor STAT1 limits pro-inflammatory programs that would otherwise restrict white adipose tissue (WAT) expansion and decrease insulin sensitivity. We also demonstrated complete elimination of IFN activity mediates many adverse effects of high fat diet, including weight gain, diminished mitochondrial function, and insulin resistance. Multiple studies, including our own, observed higher STAT1 expression in WAT of diabetic mice and humans, suggesting that IFN activity may still represent a pathogenic consequence of chronic obesity. The goal of the current cycle is to fill vital remaining gaps in our mechanistic understanding of the fundamental ways IFN transmits signals to transcriptional regulation of metabolism and insulin sensitivity in fat cells. To achieve our goal, we will demonstrate that the IFN receptor in WAT initiates the metabolic decrement of overnutrition (Aim 1) and establish the downstream transcriptional outcomes of IFN that repress cellular energy balance in the fat cell (Aim 2). Lastly, we will determine whether obesity-associated inflammation restricts a novel pathway that supports lipogenic responses necessary to sustain WAT expansion (Aim 3). Ultimately, such knowledge will teach us how to leverage the immune system to treat obesity and its co-morbidities.