Obesity and Inflammation

肥胖是一个流行的全球公共卫生问题。它是美国相当大的发病率和早期死亡率的来源，并与糖尿病、高血压、心血管疾病和癌症等风险的增加有关。人口的所有部分都受到影响，社会在总体福祉和医疗费用方面的负担是巨大的。 近年来，新的和不断发展的概念出现了，认为肥胖是一种慢性炎症内分泌紊乱。此外，在动物和人类身上的一小部分但不断增加的证据表明，肥胖本身改变了一系列基因的特征，而且至少这些炎症和基因表达的生物标记物的变化中的一部分可以通过减肥来逆转。人体内的数据相当匮乏，目前的文献中只有少数几篇关于这一主题的文章。 在这项临床方案中，我们建议通过使用标准微阵列技术对取自活检组织的皮下脂肪组织样本进行测试并再次确认超重受试者中特定的一组基因(S)被激活(或失活)，从而扩展人类的早期和进化工作。此外，我们将通过微透析法研究体内局部脂肪组织微环境来扩大和扩展这项工作，微透析法是一种微创技术，允许在生理条件下连续测定细胞外液的成分。一些脂肪因子(如瘦素和脂联素)和炎症介质、细胞因子(如肿瘤坏死因子α、白介素6)和二十烷类化合物(如前列腺素E2、脂氧素A4和白三烯B4)的作用将使用灵敏的液-质联用法和ELISA法进行分析。 研究设计包含两个基本目标： (A)非超重对照与超重受试者在基线和 (B)超重患者通过限制卡路里饮食减肥后随时间变化的相关性。 为此，将招募30名非超重对照(BMI 19.0至24.9)和80名超重受试者(BMI 25.0至45.0)。将对所有参与者进行的基线研究包括：常规和专门的血液测试、人体测量指数、空气置换体积描记仪的身体成分、间接量热法、作为胰岛素敏感性指标的静脉葡萄糖耐量试验、皮下脂肪组织微透析程序以采集局部微环境中的各种脂肪因子、细胞因子和二十烷类炎症介质，以及皮下脂肪组织活检以使用标准微阵列技术分析基因表达。这些程序将需要在临床中心过夜入院。 然后，超重的受试者将被开出限制卡路里的饮食，并跟踪观察一年。他们将每隔3个月定期进行上述相同的重复研究和程序，以评估各种参数的连续变化，并提供与所实现的减肥程度和速度相关的数据。 研究目前正在进行中，我们继续招募患者参加该方案。目前，30名正常体重和70名超重研究志愿者已经顺利完成了他们在临床中心代谢科的首次住院(基线)。对61名超重者在实施饮食干预和营养咨询后1.5个月、53个月、40个月、30个月和28个月进行了超重研究。这些患者在减肥方面取得了非凡的成功，平均减肥速度为每周0.5磅或每年25磅。微透析液和血清中炎症的脂肪因子、细胞因子和脂质介质的鉴定和定量已经开始，结果正在分析中。这些数据表明，与血清相比，微透析液中存在不同的细胞因子模式。 综上所述，这些研究应该揭示并提供对炎性细胞因子和其他介质基因表达和释放变化的本质的基本见解，这些变化表征了超重状态，以及当饮食干预导致体重减轻时发生的一系列动态事件。预计这些变化中的一些将与巨噬细胞和已知的炎症标志物有关，尽管毫无疑问还有其他重要的线索尚未发现。因此，我们希望这样的研究最终将导致识别与肥胖相关的重要代谢紊乱及其对不同治疗方式的反应的新基因。

Obesity is a global public health problem of epidemic proportions. It is the source of considerable morbidity and early mortality in the U.S. and is associated with increased risk of diabetes, hypertension, cardiovascular disease, and cancer to name a few. All segments of the population are affected and the burden to society, in terms of general well-being and healthcare costs, is tremendous. In recent years, new and evolving concepts have emerged regarding obesity as a chronic endocrine disorder of inflammation. Moreover, a small, but growing body of evidence both in animals and in man indicates that obesity per se alters the profile of a constellation of genes and that at least some of these changes in biomarkers of inflammation and gene expression can be reversed by weight loss. The data in humans is rather scant, with just a handful of articles on this subject in the current literature. In this clinical protocol, we propose to extend the early and evolving work in humans by testing and reconfirming the idea that a particular set(s) of genes is activated (or deactivated) in overweight subjects using standard microarray techniques on samples of subcutaneous adipose tissue derived from biopsies. In addition, we will broaden and extend this work by studying the local adipose tissue microenvironment in vivo by means of a microdialysis procedure, a minimally invasive technique that allows the serial determination of components of the extracellular fluid under physiological conditions. The role of a number of adipokines (such as leptin and adiponectin) and inflammatory mediators, cytokines (e.g., TNF-alpha, IL-6), and eicosanoids (such as Prostaglandin E2, Lipoxin A4, and Leukotriene B4) will be analyzed using sensitive Liquid Chromatography-Tandem Mass Spectrometry and ELISA methods. The study design incorporates two basic objectives: (a) Comparison of Non-Overweight Controls vs. Overweight Subjects at Baseline and (b) Correlation of changes in Overweight patients over time as they lose weight through a calorie-restricted diet. To these ends, 30 Non-Overweight Controls (BMI 19.0 to 24.9) and 80 Overweight Subjects (BMI 25.0 to 45.0) will be enrolled. Baseline studies, to be obtained on all participants include: routine and specialized blood tests, anthropometric indices, body composition by air-displacement plethysmography, indirect calorimetry, intravenous glucose tolerance test as an index of insulin sensitivity, subcutaneous adipose tissue microdialysis procedures to sample the local microenvironment for various adipokines, cytokines, and eicosanoid mediators of inflammation, and subcutaneous adipose tissue biopsy for analysis of gene expression using standard microarray techniques. These procedures will require an overnight hospital admission to the Clinical Center. Overweight Subjects will then be prescribed a calorie-restricted diet and followed for one year. They will undergo the same repeat studies and procedures outlined above at regular, 3-month intervals so as to assess serial changes in the various parameters and to provide correlative data with the degree and rate of weight loss achieved. Studies are currently in progress and we continue to enroll patients in the protocol. At present, 30 Normal Weight and 70 Overweight study volunteers have successfully completed their first inpatient admissions (Baseline) to the Metabolic Unit of the Clinical Center. 61 Overweight subjects have been studied at 1.5 months, 53 at 3 months, 40 at 6 months, 30 at 9 months, and 28 at 12 months following the institution of the dietary intervention and nutritional counseling. The patients have been extraordinarily successful in losing weight, the average rate of weight loss being 0.5 lbs/week or 25 lbs/year. Identification and quantitation of adipokines, cytokines, and lipid mediators of inflammation in microdialysis fluids and serum have begun and results are being analyzed. The data indicate that different patterns exist for cytokines in relation to microdialysis fluid as compared to serum. Taken together, these studies should shed light and provide fundamental insights into the nature of the altered gene expression and release of inflammatory cytokines and other mediators that characterize the overweight state and the dynamic series of events that take place when dietary intervention leads to weight loss. It is anticipated that a number of these changes will relate to macrophages and known inflammatory markers though doubtless there are other important leads yet to be discovered. Thus, our hope is that such studies will ultimately lead to the identification of novel genes that underlie the important metabolic derangements associated with obesity and their response to different treatment modalities.