A promising approach to correct the metabolic dysfunction associated with obesity is to activate brown fat non-shivering thermogenesis (NST). A critical limitation with NST as a therapeutic option, however, is that this beneficial process is silenced under human physiological temperature conditions and the mechanisms of how this occurs is unknown. This study will be the first to identify human NST silencing factors that may be targeted for the treatment of obesity and metabolic disorders.
Obesity and associated metabolic diseases such as type 2 diabetes continue to be one of the leading causes of death worldwide, demanding additional research into novel treatments beyond our current options. One promising experimental approach to overcome the metabolic dysfunctions associated with obesity, such as insulin resistance and glucose imbalance, is to activate brown fat non-shivering thermogenesis (NST). Activated human brown adipose tissue (BAT) increases energy expenditure at a molecular level and is associated with both improved insulin tolerance and glucose homeostasis. A critical limitation with human brown fat as a therapeutic option, however, is that its beneficial metabolic potential is restricted in a silenced state under physiological temperature conditions for most of human life. The regulatory factors that govern this silencing process are completely unknown. While many groups continue to seek novel mechanisms to activate brown fat, this study presents a unique approach, aiming to decipher the mechanisms that govern human brown fat silencing. The study hypothesizes that if the regulatory factors that silence brown fat NST can be defined, then these factors can be targeted for ablation to eliminate the "off switch", thereby keeping brown fat in a constitutively active state. Identification of human NST silencing factors will be critical to unlocking the metabolic benefits of human brown fat and would represent promising treatment opportunities for type 2 diabetes and other obesity-related disorders. Understanding these relationships will allow for precision treatment opportunities for type 2 diabetes in the future. The overall goal of this study is to unlock the metabolic benefits of human brown fat by defining the regulatory mechanisms that keep BAT in a silenced state. The study will generate the first human secretome (list of secreted proteins in blood) and transcriptome (list of gene transcripts in adipose tissue) compendium from human plasma and subcutaneous adipose tissue respectively which will be composed of target proteins, metabolites, and genes that are differentially expressed in response to NST silencing conditions. Top candidates from the profiling will then be functionally validated in human adipocytes for their role in NST silencing. The study will be an important resource for the field and will identify novel candidates that may harbor regulatory potential to govern the NST silencing process in humans. These factors can then be targeted to promote the constitutive activation of NST in order to overcome the metabolic dysfunction associated with obesity and metabolic disease. Given the invasive nature of direct human brown fat sampling, the study will instead interrogate circulating factors in human plasma as a proxy for metabolic health. In addition, the study will also obtain subcutaneous adipose tissue for RNA profiling to identify genes that are upregulated under NST-silenced conditions compared to cold exposure.
A cold vest will be placed on the participant which consists of a water-perfused wearable vest, size S-M or M-L with adjustable straps attached to a small 'cooler' reservoir to circulate cold water between the vest and the cooler (Polar Products, Stow, OH- Product link: www.polarproducts.com/polarshop/pc/CoolOR-13-Quart-System-with-Arctic-Chiller-p24757.htm) This product is safe and recommended by experimental guidelines for human BAT studies. Participants will be cold exposed for a period of 3 hours resting in a reclined position engaged in reading and/or digital entertainment of their choice.
Following cold exposure, the cold vests will be removed, and participants will be offered a warm blanket to ease the transition from cold back to warm temperatures. Participants will then be moved to an adjacent warm room maintained at 30 degrees celsius and asked to return to the resting position of their choice. Participants will then engage in reading and/or digital entertainment for a 3-hour warm exposure period.
Rockefeller University
New York, New York, United States
Identification of adipose tissue transcriptome
RNA sequencing to measure and identify a list of gene transcripts that are differentially expressed before and after re-warming. A true change is defined as 1.5 fold increase or decrease in gene expression.
Time frame: Before and after 3-hour rewarming period.
Identification of cold and warm-regulated proteome.
Proteins will be captured from blood and analyzed via mass spectrometry which generates a list of proteins for each sample. The investigators will compare the mean fold change (true change is greater than 1.5 fold) in protein abundance at the specified study time points.
Time frame: Before and after 3 hour cold exposure period and before and after 3 hour rewarming period.
Identification of cold and warm-regulated metabolome.
Metabolites will be captured from blood and analyzed via mass spectrometry which generates a list of metabolites for each sample. The investigators will compare the mean fold change (true change is greater than 1.5 fold) in metabolite abundance at the specified study time points.
Time frame: Time frame will be before and after 3 hour cold exposure period as well as before and after 3 hour rewarming period.
Nutritional assessments of individuals correlated to expression patterns of human silencer regulatory factors.
Diet History Questionnaire III (DHQ III) to assess food consumption patterns as it relates to the Dietary Guidelines for Americans.
Time frame: Baseline
Body Mass Index (BMI) correlated to expression patterns of human silencer regulatory factors.
BMI is calculated by weight and height measured by anthropometric assessments, using the formula weight in kilograms divided by height in meters squared (kilograms/meter\^2).
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Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
80
Participants will be requested to refrain from food and caloric drinks for 12 hours (starting at 8pm) prior to the study visit. Blood will then be drawn the following morning (between 8 and 9am) 30mins later following a breakfast meal (9:30am- 10am). Participants will be housed in a room with ambient temperature at 25 degrees celsius between the two blood draws.
Time frame: Baseline
Fat mass body composition (%) measured by Bod Pod correlated to expression patterns of human silencer regulatory factors.
Bod Pod uses Air Displacement Plethysmography (ADP) to determine body composition, the ratio of fat mass to lean mass. The investigators will measure fat mass composition in units of percentage (%).
Time frame: Baseline
Lean Mass body composition (%) measured by Bod Pod correlated to expression patterns of human silencer regulatory factors.
Bod Pod uses Air Displacement Plethysmography (ADP) to determine body composition, the ratio of fat mass to lean mass. The investigators will measure lean mass composition in units of percentage (%).
Time frame: Baseline