Magnuson Aaron M, Fouts Josephine K, Regan Daniel P, Booth Andrea D, Dow Steve W, Foster Michelle T
Department of Food Science and Human Nutrition, USA.
Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA.
Physiol Behav. 2018 Jun 1;190:71-81. doi: 10.1016/j.physbeh.2018.02.044. Epub 2018 Mar 1.
Obesity-related adverse health consequences occur predominately in individuals with upper body fat distribution commonly associated with increased central adiposity. Visceral adipose tissue accumulation is described to be the greatest driver of obesity-induced inflammation, however evidence also supports that the intestines fundamentally contribute to the development of obesity-induced metabolic disease. The visceral adipose depot shares the same vasculature and lymph drainage as the small intestine. We hypothesize that the visceral lymph node, which drains adipose tissue and the gastrointestinal tract, is central to the exacerbation of systemic pro-inflammation. Male C57BL/6 mice were fed CHOW or high fat diet (HFD) for 7 weeks. At termination the mesenteric depot, visceral lymph node and ileum, jejunum and Peyer's patches were collected. Cytokine concentration was determined in adipose tissue whereas immune cell populations where investigated in the visceral lymph node and intestinal segments by flow cytometry. Visceral adipose tissue and the gastrointestinal tract mutually influence immune cells enclosed within the visceral lymph node. HFD increased visceral lymph node immune cell number. This likely resulted from 1.) an increase in immune cells migration from the small intestines likely from activated dendritic cells that travel to the lymph node and 2.) cytokine effluent from visceral adipose tissue that promoted expansion, survival and retention of pro-inflammatory immune cells. Overall, the visceral lymph node, the immune nexus of visceral adipose tissue and the small intestines, likely plays a fundamental role in exacerbation of systemic pro-inflammation by HFD-induced obesity. The research of Tim Bartness greatly enhanced the understanding of adipose tissue regulation. Studies from his laboratory significantly contributed to our awareness of extrinsic factors that influence body fatness levels. Specifically, the work he produced eloquently demonstrated that adipose tissue was more complex than an insulating storage center; it was connected to our brains via the sympathetic and sensory nervous system. Mapping studies demonstrated that adipose tissue both receives and sends information to the brain. Further, his lab demonstrated that nervous system connections contributed to lipolysis, thermogenesis and adipocyte proliferation and growth. The work of Tim Bartness will continue to influence adipose tissue research. As such, Tim Bartness directly inspired the following research. Adipose tissue extrinsic factors are not limited to the peripheral nervous system. The lymphatic system is an additional extrinsic factor that cross talks with adipose tissue, however its role in this context is under emphasized. Here we begin to elucidate how the lymphatic system may contribute to the comorbidities associated with visceral adipose tissue accumulation.
与肥胖相关的不良健康后果主要发生在具有上身脂肪分布的个体中,这种分布通常与中心性肥胖增加有关。内脏脂肪组织的积累被认为是肥胖诱导炎症的最大驱动因素,然而,有证据也支持肠道在肥胖诱导的代谢疾病发展中起根本作用。内脏脂肪库与小肠共享相同的血管系统和淋巴引流。我们假设,引流脂肪组织和胃肠道的内脏淋巴结是全身促炎反应加剧的核心。雄性C57BL/6小鼠喂食普通饲料或高脂饮食(HFD)7周。在实验结束时,收集肠系膜脂肪库、内脏淋巴结以及回肠、空肠和派尔集合淋巴结。测定脂肪组织中的细胞因子浓度,而通过流式细胞术在内脏淋巴结和肠段中研究免疫细胞群体。内脏脂肪组织和胃肠道相互影响内脏淋巴结内的免疫细胞。高脂饮食增加了内脏淋巴结免疫细胞数量。这可能是由于1.)从小肠迁移来的免疫细胞增加,可能来自迁移至淋巴结的活化树突状细胞;2.)内脏脂肪组织中的细胞因子流出,促进了促炎免疫细胞的扩增、存活和滞留。总体而言,内脏淋巴结作为内脏脂肪组织和小肠的免疫枢纽,可能在高脂饮食诱导的肥胖导致的全身促炎反应加剧中起重要作用。蒂姆·巴特尼斯的研究极大地增进了对脂肪组织调节的理解。他实验室的研究显著提高了我们对影响体脂水平的外在因素的认识。具体而言,他所开展的工作有力地证明了脂肪组织比一个绝缘的储存中心更为复杂;它通过交感神经和感觉神经系统与我们的大脑相连。图谱研究表明脂肪组织既能接收也能向大脑发送信息。此外,他的实验室证明神经系统连接有助于脂肪分解、产热以及脂肪细胞的增殖和生长。蒂姆·巴特尼斯的工作将继续影响脂肪组织研究。因此,蒂姆·巴特尼斯直接启发了以下研究。脂肪组织的外在因素不仅限于外周神经系统。淋巴系统是另一个与脂肪组织相互作用的外在因素,然而其在这方面的作用未得到充分重视。在此,我们开始阐明淋巴系统可能如何导致与内脏脂肪组织积累相关的合并症。