Development of obesity and metabolic clinical research programs

1. 我们正在进行的名为“热中性区周围一系列环境温度下的能量消耗反应”的临床方案（12-DK-0097, NCT01568671）的开发是为了提高我们对人体能量消耗动态调节的理解，以应对环境温度的细微变化。我们特别感兴趣的是研究兼性产热的能力，定义为对环境温度变化的能量消耗（EE或产热）的增加。结合我们和其他实验室正在进行的关于棕色脂肪组织及其在非寒颤致热作用中的作用的研究，这样的临床研究正在能量代谢和肥胖领域产生巨大的兴趣。我们在连续10-13天（为期2周的住院治疗方案）中，在随机环境温度范围为16℃至31℃的房间量热计中测量了5小时内的静息能量消耗。我们还通过体表肌电图（EMG）、加速度和心率、皮肤和核心体温以及血液和尿液标记物的应激反应仔细测量了潜在的颤抖，同时控制了身体活动、服装、姿势和饮食摄入。第一个（也是主要的）假设是，与非肥胖受试者相比，肥胖受试者的较低临界温度（定义冷致产热开始的温度）会降低。到目前为止，我们已经成功地研究了15（15）名健康的瘦男性志愿者作为我们的标准对照组，以及6(6)名年龄和种族/民族匹配的健康肥胖男性志愿者。初步数据分析表明，我们可以在2.5%的变异系数范围内再现热中性区（TNZ）的静息EE，通过肌电图和心率检测寒战发作，以及非寒战产热的斜率和最大容量（瘦人比肥胖者更明显），所有这些都有助于我们理解定义动态人体热生物学的参数。我们还观察到，在相同的降温水平下，肥胖受试者的产热反应相对减弱，但与此同时，这些受试者开始颤抖的温度与瘦受试者相似；然而，我们需要积累更多的肥胖受试者来证实我们的初步观察结果。然而，由于多次筛查失败，我们在成功招募健康的肥胖年轻男性时遇到了越来越多的困难，并且在没有减肥益处的情况下，我们对两周的住院治疗犹豫不决。我们正在加大努力，在更广泛的领域进行招募，希望在2015财年完成12名肥胖受试者。

1. Our ongoing clinical protocol titled Energy expenditure responses to a range of environmental temperatures around the thermal neutral zone (12-DK-0097, NCT01568671) was developed to improve our understanding of human dynamic regulation of energy expenditure in response to subtle changes in environmental temperature. In particular, we are interested in studying the capacity of facultative thermogenesis, defined as an increase in energy expenditure (EE or heat production) to a changed environmental temperature. Combined with the ongoing research on brown adipose tissue and its role in non-shivering thermogensis in our and other labs, such clinical research is generating substantial interests in the field of energy metabolism and obesity. We measured resting energy expenditure in a 5-hour period in the room calorimeter with randomized environmental temperature ranging between 16C and 31C, in 10-13 consecutive days (a 2-week inpatient protocol). We also carefully measured potential shivering by surface electromyography (EMG), acceleration, and heart rate, skin and core body temperatures, and stress responses by blood and urinary markers, while controlling for physical activity, clothing, posture, and dietary intake. The first (and the primary) hypothesis is that the lower critical temperature (that defines the beginning of cold-induced thermogenesis) will be reduced in obese as compared to non-obese subjects. To date, we have successfully studied fifteen (15) healthy lean male volunteers as our normative control group and six (6) healthy obese male volunteers matched for age and race/ethnicity. Preliminary data analyses showed that we could reproduce the resting EE in the thermal neutral zone (TNZ) within 2.5% coefficient of variation, detect shivering onset with EMG and heart rate, and the slope and the maximum capacity of non-shivering thermogenesis (in lean more so than in the obese), all of which are helping us to understand the parameters that define the dynamic human thermobiology to a range of environmental temperatures that have not been available. We are also observing a relatively blunted thermogenic response under the same level of cooling in obese subjects but in the same time, these subjects begin the shiver similar room temperature as the lean subjects; however, we need to accrual more obese subjects to confirm our preliminary observations. However, we have experienced increased difficulties successfully recruiting healthy obese young males due to multiple failed screenings and hesitations to commit to the 2-week inpatient stays without the benefits of losing weight. We are increasing our efforts to recruit in a broader area and hoping that will lead to the completion of 12 obese subjects in FY15. 2. At the end of FY13, we developed a new clinical protocol to use a pharmacologic approach to dissect the mechanism of NST (13-DK-0200, NCT01950520). Since the principal physiologic stimulus to BAT (and possibly muscle) NST is via sympathetic nervous system, we hypothesize that, by careful measurements of NST and using -adrenergic drugs that differ in receptor specificity and agonist/antagonist properties, we will gain better understanding of the regulation of human NST and resting EE. The second phase of the study focuses on measuring anti-obesity drugs potential effect on basal metabolic rate. The rationale is that previous studies of drug effect on EE in humans have not always rigorously enforced the use of thermoneutrality, thus may have increased variability and underestimated effects, contributing to inconclusive findings. We have studied six (6) healthy subjects to date for the first phase, and fully prepared to increase the recruitment in this phase and begin the second phase in FY15. 3. We followed up on the past studies (through collaborations with Dr. Francesco Celi) which we successfully linked measured BAT activation via 18F-fluro-deoxyglucose (FDG) positron emission tomography (PET) with individual acute (12-hr overnight) cold-induced thermogenesis in a group of non-obese men and women, we designed and conducted a clinical trial (13-DK-0013, ClinicalTrials.gov:NCT01730105 ) to investigate if BAT can be recruited by a lower ambient temperature at nighttime. This was a 4-month prospective crossover design with four consecutive blocks of 1-month overnight inpatient temperature acclimation (24C, 19C, 24C, and 27C). Five healthy young males completed the study, and demonstrated that BAT abundance and activity was boosted by cold exposure (19C), and reversely suppressed by warm (27C). We further demonstrated that the degree of BAT modulation after cold acclimation was associated to diet-induced thermogenesis and post-prandial insulin sensitivity. These results suggest regulatory links between BAT thermal plasticity and glucose metabolism in humans, opening avenues to harnessing BAT for potential metabolic benefits in the area of glucose utilization more so than just thermogenesis. 4. In 2012-13, Irisin and FGF21 became interesting targets of research as potential modulators for BAT and perhaps beige fat. Collaborating with Dr. Celi and his fellow Dr. Paul Lee, we conducted a series of studies under the protocols 07-DK-0202 and 13-DK-0013 (ClinicalTrials.gov:NCT 00521729 and 01730105, respectively). we explored whether cold exposure is an afferent signal for irisin secretion in humans and compared it with FGF21, a brown adipokine in rodents. Cold exposure increased circulating irisin and FGF21. In ten (10) subjects, we found an induction of irisin secretion proportional to shivering intensity, in magnitude similar to exercise-stimulated secretion. Irisin (FNDC5) and/or FGF21 treatment upregulated human adipocyte brown fat gene/protein expression and thermogenesis in a depot-specific manner. These results suggest exercise-induced irisin secretion could have evolved from shiveringrelated muscle contraction, serving to augment brown fat thermogenesis in concert with FGF21. Irisin-mediated muscle-adipose crosstalk may represent a thermogenic, cold-activated endocrine axis that is exploitable in obesity therapeutics development.