Glucocorticoids modulate human brown adipose tissue thermogenesis in vivo

Introduction: Brown adipose tissue (BAT) is a thermogenic organ with substantial metabolic capacity and has important roles in the maintenance of body weight and metabolism. Regulation of BAT is primarily mediated through the ß-adrenoceptor (ß-AR) pathway. The in vivo endocrine regulation of this pathway in humans is unkown. The objective of our study was to assess the in vivo BAT temperature responses to acute glucocorticoid administration. Methods: We studied 8 healthy male volunteers, not pre-selected for BAT presence or activity and without prior BAT cold-activation, on two occasions, following an infusion with hydrocortisone (0.2 mg.kg-1.min-1 for 14 hours) and saline, respectively. Infusions were given in a randomized double-blind order. They underwent assessment of supraclavicular BAT temperature using infrared thermography following a mixed meal, and during ß-AR stimulation with isoprenaline (25 ng.kg fat-free mass-1.min-1 for 60 min) in the fasting state. Results: During hydrocortisone infusion, BAT temperature increased both under fasting basal conditions and during ß-AR stimulation. We observed a BAT temperature threshold, which was not exceeded despite maximal ß-AR activation. We conclude that BAT thermogenesis is present in humans under near-normal conditions. Glucocorticoids modulate BAT function, representing important physiological endocrine regulation of body temperature at times of acute stress

Antisense oligonucleotide and thyroid hormone conjugates for obesity treatment

Using the principle of antibody-drug conjugates that deliver highly potent cytotoxic agents to cancer cells for cancer therapy, we here report the synthesis of antisense-oligonucleotides (ASO) and thyroid hormone T3 conjugates for obesity treatment. ASOs primarily target fat and liver with poor penetrance to other organs. Pharmacological T3 treatment increases energy expenditure and causes weight loss, but is contraindicated for obesity treatment due to systemic effects on multiple organs. We hypothesize that ASO-T3 conjugates may knock down target genes and enrich T3 action in fat and liver. Two established ASOs are tested. Nicotinamide N-methyltransferase (NNMT)-ASO prevents diet- induced obesity in mice. Apolipoprotein B (ApoB)-ASO is an FDA approved drug for treating familial hypercholesterolemia. NNMT-ASO and ApoB-ASO are chemically conjugated with T3 using a non- cleavable sulfo-SMCC linker. Both NNMT-ASO-T3 (NAT3) and ApoB-ASO-T3 (AAT3) enhance thyroid hormone receptor activity. Treating obese mice with NAT3 or AAT3 decreases adiposity and increases lean mass. ASO-T3 enhances white fat browning, decreases genes for fatty acid synthesis in liver, and shows limited effects on T3 target genes in heart and muscle. Furthermore, AAT3 augments LDL cholesterol-lowering effects of ApoB-ASO. Therefore, ASO and hormone/drug conjugation may provide a novel strategy for obesity and hyperlipidemia treatment