Sirtuin 1 (SIRT1) is a sensor of cell energy availability, and with leptin and adiponectin, it regulates metabolic homeostasis. Widely studied in tissues, SIRT1 is under evaluation as a plasmatic marker. We aimed at assessing whether circulating SIRT1 behaves consistently with leptin and adiponectin in conditions of deficiency, excess or normal fat content. Eighty subjects were evaluated: 27 with anorexia nervosa (AN), 26 normal-weight and 27 with obesity. Bloodstream SIRT1, leptin and adiponectin (ELISA), total and trunk fat mass (FM) %, abdominal visceral adipose tissue, liver steatosis and epicardial fat thickness (EFT) were assessed. For each fat store, the coefficient of determination (R2) was used to evaluate the prediction capability of SIRT1, leptin and adiponectin. Plasma SIRT1 and adiponectin coherently decreased with the increase of FM, while the opposite occurred with leptin. Mean levels of each analyte were different between groups (p < 0.005). A significant association between plasma variables and FM depots was observed. SIRT1 showed a good predictive strength for FM, particularly in the obesity group, where the best R2 was recorded for EFT (R2 = 0.7). Blood SIRT1, adiponectin and leptin behave coherently with FM and there is synchrony between them. The association of SIRT1 with FM is substantially superimposable to that of adiponectin and leptin. Given its homeostatic roles, SIRT1 may deserve to be considered as a plasma clinical/biochemical parameter of adiposity and metabolic health.

Ketone bodies (KBs) and Sirtuin-1 (SIRT1) have received increasing attention over the past two decades given their pivotal function in a variety of biological contexts, including transcriptional regulation, cell cycle progression, inflammation, metabolism, neurological and cardiovascular physiology, and cancer. As a consequence, the modulation of KBs and SIRT1 is considered a promising therapeutic option for many diseases. The direct regulation of gene expression can occur in vivo through histone modifications mediated by both SIRT1 and KBs during fasting or low-carbohydrate diets, and dietary metabolites may contribute to epigenetic regulation, leading to greater genomic plasticity. In this review, we provide an updated overview of the epigenetic interactions between KBs and SIRT1, with a particular glance at their central, synergistic roles for metabolic health.

Sirtuin1 (SIRT1) and sclerostin play important roles in adipose tissue and bone metabolism. We evaluated the circulating SIRT1 and sclerostin relationship with mass and quality of bone while considering the degree of adiposity. Sixty-six premenopausal women (16 underweight, 25 normal weight and 25 with obesity), aged <50 years, were enrolled. Plasma SIRT1, sclerostin and DXA body composition (total fat mass (FM), abdominal visceral adipose tissue, lean mass, trabecular bone score (TBS) and lumbar spine and femoral neck (FN) bone mineral density (BMD)) were assessed. The patients with obesity showed the lowest SIRT1 and TBS values and the highest sclerostin concentrations; BMD increased with FM and BMI and had an inverse association with SIRT1. Sclerostin was negatively correlated with SIRT1 (ρ = −0.37, p = 0.002). When spine BMD, FN BMD and TBS were standardized for BMI, a positive correlation with SIRT1 and a negative correlation with sclerostin were seen (p < 0.005). In the regression analysis, sclerostin was the best independent, negative predictor for BMD and TBS, while SIRT1 directly predicted TBS (p < 0.05). In conclusion, blood measurement of SIRT1 and sclerostin could represent a snapshot of the bone status that, taking into account the degree of adiposity, may reduce the interference of confounding factors in the interpretation of bone health parameters.

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