Plasma irisin depletion under energy restriction is associated with improvements in lipid profile in metabolic syndrome patients

Objective A recently discovered myokine, irisin, may have an important role in energy metabolism. This study aimed to evaluate the relationship between this hormone and the lipid profile of Metabolic Syndrome (MetS) patients following a hypocaloric diet. Design Ninety-three Caucasian adults (52 men/41 women) diagnosed with MetS followed an 8-week-long energy restricted programme (-30% of the energy requirements). Anthropometric measurements, biochemical markers and plasma irisin levels were analysed before and after the nutritional intervention. Results Global plasma irisin levels were significantly reduced at the end of the study (-72•0 ± 100•9 ng/mL, p < 0•001) accompanying the weight loss (-6•9%). The depletion of irisin significantly correlated with changes in some atherogenic-related variables: total cholesterol (B = 0•106, p = 0•018), total cholesterol/high density lipoprotein-cholesterol ratio (B = 0•002, p = 0•036), low density lipoprotein-cholesterol (B = 0•085, p = 0•037) and apolipoprotein B (B = 0•052, p = 0•002), independently of changes in body weight. Conclusions An association between the reduction of plasma irisin levels and the depletion of important lipid metabolism biomarkers was observed in patients with MetS undergoing an energy restricted programme

Exercise training and cold exposure trigger distinct molecular adaptations to inguinal white adipose tissue

Summary: Exercise training and cold exposure both improve systemic metabolism, but the mechanisms are not well established. Here, we tested the hypothesis that inguinal white adipose tissue (iWAT) adaptations are critical for these beneficial effects and determined the impact of exercise-trained and cold-exposed iWAT on systemic glucose metabolism and the iWAT proteome and secretome. Transplanting trained iWAT into sedentary mice improves glucose tolerance, while cold-exposed iWAT transplantation shows no such benefit. Compared to training, cold leads to more pronounced alterations in the iWAT proteome and secretome, downregulating >2,000 proteins but also boosting the thermogenic capacity of iWAT. In contrast, only training increases extracellular space and vesicle transport proteins, and only training upregulates proteins that correlate with favorable fasting glucose, suggesting fundamental changes in trained iWAT that mediate tissue-to-tissue communication. This study defines the unique exercise training- and cold exposure-induced iWAT proteomes, revealing distinct mechanisms for the beneficial effects of these interventions on metabolic health

Leptin treatment reduces body fat but does not affect lean body mass or the myostatin-follistatin-activin axis in lean hypoleptinemic women

Animal studies in vivo indicate that leptin treatment in extremely leptin-sensitive ob/ob mice reduces body weight exclusively by reducing fat mass and that it increases muscle mass by downregulating myostatin expression. Data from human trials are limited. Therefore, we aimed at characterizing the effects of leptin administration on fat mass, lean body mass, and circulating regulators of muscle growth in hypoleptinemic and presumably leptin-sensitive human subjects. In an open-label, single-arm trial, seven lean, strenuously exercising, amenorrheic women with low leptin concentrations (≤5 ng/ml) were given recombinant methionyl human leptin (metreleptin; 0.08 mg·kg−1·day−1) for 10 wk. In a separate randomized, double-blind, placebo-controlled trial, seven women were given metreleptin (initial dose: 0.08 mg·kg−1·day−1 for 3 mo, increased thereafter to 0.12 mg·kg−1·day−1 if menstruation did not occur), and six were given placebo for 9 mo. Metreleptin significantly reduced total body fat by an average of 18.6% after 10 wk (P < 0.001) in the single-arm trial and by 19.5% after 9 mo (placebo subtracted; P for interaction = 0.025, P for metreleptin = 0.004) in the placebo-controlled trial. There were no significant changes in lean body mass (P ≥ 0.33) or in serum concentrations of myostatin (P ≥ 0.35), follistatin (P ≥ 0.30), and activin A (P ≥ 0.20) whether in the 10-wk trial or the 9-mo trial. We conclude that metreleptin administration in lean hypoleptinemic women reduces fat mass exclusively and does not affect lean body mass or the myostatin-follistatin-activin axis