The comprehensive assessment of long-term effects of reducing intake of energy (CALERIE-II; NCT00427193) clinical trial established that caloric restriction (CR) in humans lowers inflammation. The identity and mechanism of endogenous CR-mimetics that can be deployed to control obesity-associated inflammation and diseases are not well understood. Our studies have found that 2 years of 14% sustained CR in humans inhibits the expression of the matricellular protein, secreted protein acidic and rich in cysteine (SPARC), in adipose tissue.
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View Article and Find Full Text PDFThermogenesis in brown and beige adipose tissue has important roles in maintaining body temperature and countering the development of metabolic disorders such as obesity and type 2 diabetes. Although much is known about commitment and activation of brown and beige adipose tissue, its multiple and abundant immunological factors have not been well characterized. Here we define a critical role of IL-27-IL-27Rα signalling in improving thermogenesis, protecting against diet-induced obesity and ameliorating insulin resistance.
View Article and Find Full Text PDFDuring aging, visceral adiposity is often associated with alterations in adipose tissue (AT) leukocytes, inflammation, and metabolic dysfunction. However, the contribution of AT B cells in immunometabolism during aging is unexplored. Here, we show that aging is associated with an expansion of a unique population of resident non-senescent aged adipose B cells (AABs) found in fat-associated lymphoid clusters (FALCs).
View Article and Find Full Text PDFThe role of the immune system in homeostasis of pancreatic β cells in type 2 diabetes mellitus is poorly characterized. In a recent issue of Cell Metabolism, Ying et al. (2018) report that two subpopulations of macrophages expand during obesity to impair β cell function.
View Article and Find Full Text PDFHypothyroidism, a metabolic disease characterized by low thyroid hormone (TH) and high thyroid-stimulating hormone (TSH) levels in the serum, is strongly associated with nonalcoholic fatty liver disease (NAFLD). Hypothyroidism-induced NAFLD has generally been attributed to reduced TH signaling in the liver with a consequent decrease in lipid utilization. Here, we found that mildly hypothyroid mice develop NAFLD without down-regulation of hepatic TH signaling or decreased hepatic lipid utilization.
View Article and Find Full Text PDFCatecholamine-induced lipolysis, the first step in the generation of energy substrates by the hydrolysis of triglycerides, declines with age. The defect in the mobilization of free fatty acids in the elderly is accompanied by increased visceral adiposity, lower exercise capacity, failure to maintain core body temperature during cold stress, and reduced ability to survive starvation. Although catecholamine signalling in adipocytes is normal in the elderly, how lipolysis is impaired in ageing remains unknown.
View Article and Find Full Text PDFIn concert with their phagocytic activity, macrophages are thought to regulate the host immunometabolic responses primarily via their ability to produce specific cytokines and metabolites. Here, we show that IL-4-differentiated, M2-like macrophages secrete IGF1, a hormone previously thought to be exclusively produced from liver. Ablation of IGF1 receptors from myeloid cells reduced phagocytosis, increased macrophages in adipose tissue, elevated adiposity, lowered energy expenditure, and led to insulin resistance in mice fed a high-fat diet.
View Article and Find Full Text PDFThe hallmarks of age-related immune senescence are chronic inflammation, aberrant expansion of effector memory, and loss of naive T lymphocytes due in part to systemic activation of innate immune sensor NLRP3 inflammasome in myeloid lineage cells. The endogenous mechanisms that regulate inflammasome activation during aging are unknown. Here, we present evidence that growth hormone receptor (GH-R)-dependent downregulation of NLRP3 inflammasome in macrophages is linked to pro-longevity effects that maintain immune system homeostasis in aging.
View Article and Find Full Text PDFBackground: Organogenesis of the thyroid gland requires the Pax8 protein. Absence or reduction of Pax8 results in congenital hypothyroidism in animal models and humans, respectively. This study aims at elucidating the regulatory mechanism leading to the expression of Pax8 in thyroid cells.
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