Integrative Mechanisms of Adipose Tissue Dysfunction In obesity

描述(申请人提供)：即使在考虑了缺乏体力活动和遗传易感性之后，过量的食物能量摄入仍然可能是西方国家超重和肥胖的最常见原因。不幸的是，扩张的脂肪组织经历了循环白细胞的异常渗透，这一现象发生在微循环中，与脂肪组织炎症和胰岛素抵抗有关。在扩张的脂肪储存库的微循环中，启动和控制白细胞外溢的确切细胞和分子机制仍不清楚。因此，白细胞渗透是否是脂肪细胞功能障碍的原因或影响仍在很大程度上尚不清楚，这阻碍了对美国不断增长的肥胖人口的治疗干预。文献中新出现的信息和在本申请中提出的新的初步数据表明，营养过载导致餐后中性粒细胞在内脏脂肪库中的渗透。显然，这种对饮食营养的急性反应发生在体重增加和胰岛素抵抗之前很久。因此，我们建议检验这样一种假设，即营养过载会剧烈地激活内脏脂肪微循环中的白细胞-内皮相互作用，并且这一过程会引发脂肪细胞功能障碍。该项目的总体目标是研究：a)营养超负荷触发脂肪组织微循环中性粒细胞快速激活的机制；b)使内脏脂肪库的微循环对营养超负荷高度反应的细胞和分子决定因素；c)这种现象对脂肪细胞动态平衡的影响。为了实施这些研究，我们将利用基因敲除和转基因小鼠技术以及下列生物化学和生理学技术：蛋白质印迹分析、免疫组织化学和免疫荧光、细胞和组织分离技术、活体显微镜、一氧化氮测量。我们希望这项工作的结果将促进我们对启动和维持脂肪组织炎症和相关代谢紊乱的综合机制的理解。

DESCRIPTION (provided by applicant): Even after accounting for lack of physical activity and genetic susceptibility, excessive food energy intake remains, probably, the most common cause of overweight and obesity in western countries. Unfortunately, the expanding adipose tissue experiences an abnormal infiltration of circulating leukocytes, a phenomenon that occurs in the microcirculation and it is associated with adipose tissue inflammation and insulin resistance. The precise cellular and molecular mechanisms that initiate and govern leukocyte extravasation in the microcirculation of expanding adipose depots remain undefined. Consequently, whether leukocyte infiltration is the cause or the effect of adipocyte dysfunction remains largely unknown, which hinders therapeutic interventions in the ever-growing obese population of the USA. Emerging information in the literature and new preliminary data presented in this application demonstrate that nutrients overload causes a postprandial infiltration of neutrophils in visceral fat depots. Obviously, this acute response to dietary nutrients occurs well before weight gain and insulin resistance. Accordingly, we propose to test the hypothesis that nutrients overload acutely activates leukocyte-endothelium interactions in the microcirculation of the visceral fat and that this process initiates adipocyte dysfunction. The overall goals of this projet are to study: a) the mechanisms by which nutrients overload triggers this rapid activation of neutrophils in the adipose tissue microcirculation; b) the cellular and molecular determinants that make the microcirculation of visceral fat depots highly responsive to nutrients overload; c) the impact of this phenomenon on adipocyte homeostasis. To implement these studies, we will utilize knockout and transgenic mouse technology along with the following biochemistry and physiology techniques: western blot analysis, immunohistochemistry and immunofluorescence, cells and tissue isolation techniques, intravital microscopy, nitric oxide measurements. We hope that the results of this work will advance our understanding of the integrated mechanisms that initiate and maintain adipose tissue inflammation and related metabolic disorders.