Citations

Abstract Aims Obesity is a risk factor for heart failure with preserved ejection fraction (HFpEF), particularly in women, but the mechanisms remain unclear. The present study aimed to investigate the impact of central adiposity in patients with HFpEF and explore potential sex differences. Methods and results A total of 124 women and 105 men with HFpEF underwent invasive haemodynamic exercise testing and rest echocardiography. Central obesity was defined as a waist circumference (WC) ≥88 cm for women and ≥102 cm for men. Exercise‐normalized pulmonary capillary wedge pressure (PCWP) responses were evaluated by the ratio of PCWP to workload (PCWP/W) and after normalizing to body weight (PCWL). The prevalence of central obesity (77%) exceeded that of general obesity (62%) defined by body mass index ≥30 kg/m 2 . Compared to patients without central adiposity, patients with HFpEF and central obesity displayed greater prevalence of diabetes and dyslipidaemia, higher right and left heart filling pressures and pulmonary artery pressures during exertion, and more severely reduced aerobic capacity. Associations between WC and fasting glucose, low‐density lipoprotein (LDL) cholesterol, peak workload, and pulmonary artery pressures were observed in women but not in men with HFpEF. Although increased WC was associated with elevated PCWP in both sexes, the association with PCWP/W was observed in women but not in men. The strength of correlation between PCWP/W and WC was more robust in women with HFpEF as compared to men (Meng's test p = 0.0008), and a significant sex interaction was observed in the relationship between PCWL and WC ( p for interaction = 0.02). Conclusions Central obesity is even more common than general obesity in HFpEF, and there appear to be important sexual dimorphisms in its relationships with metabolic abnormalities and haemodynamic perturbations, with greater impact in women.

Background: Normal weight adults gain leg fat gain via adipocyte hyperplasia and upper body subcutaneous (UBSQ) fat gain via adipocyte hypertrophy. Objective: To understand whether regional fat loss mirrors fat gain and whether leg fat loss results in decreased adipocyte number vs. size. Design: We assessed UBSQ, leg and visceral fat gain and loss in response to over- and underfeeding in 23 young, healthy normal weight adults (15 men). Participants gained ∼5% weight over 8 weeks and lost ∼80% of gained fat over the following 8 weeks. We measured abdominal subcutaneous and femoral adipocyte size and number after weight gain and loss. Results: Volunteers gained 3.1 ± 2.1 kg of body fat with overfeeding and lost 2.4 ± 1.7 kg with calorie restriction. Although upper body subcutaneous (UBSQ) fat and visceral fat gains were completely reversed with weight loss, leg fat had not yet returned to baseline values by 8 weeks. Abdominal and femoral adipocyte size decreased significantly with weight loss, but the number of adipocytes did not decrease. Abdominal adipocyte size decreases correlated (rho= 0.76, p = 0.001) with UBSQ fat mass decreases and femoral adipocyte size decreases correlated (rho= 0.49, p=0.05) with leg fat mass decreases. Conclusion: UBSQ and visceral fat depots increase and decrease proportionately with short term weight gain and loss, whereas gain and loss of leg fat are less well linked. Loss of lower body fat is due to reduced fat cell size, not number, which may result in long-term increases in leg fat cell number. This may have implications for long-term weight control.

The role of adipose tissue (AT) inflammation in AT function in humans is unclear. We tested whether AT macrophage (ATM) content, cytokine gene expression, and senescent cell burden (markers of AT inflammation) predict AT insulin resistance measured as the insulin concentration that suppresses lipolysis by 50% (IC50). We studied 86 volunteers with normal weight or obesity at baseline and a subgroup of 25 volunteers with obesity before and after weight loss. There was a strong positive relationship between IC50 and abdominal subcutaneous and femoral fat cell size (FCS). The positive, univariate relationships between IC50 and abdominal AT inflammatory markers CD68, CD14, CD206 ATM/100 adipocytes, senescent cells, IL-6, and TNF-α mRNA were not significant after adjustment for FCS. A 10% weight loss significantly reduced IC50; however, there was no reduction in adipose ATM content, senescent cells, or cytokine gene expression. Our study suggests that commonly used markers of AT inflammation are not causally linked to AT insulin resistance, whereas FCS is a strong predictor of AT insulin resistance with respect to lipolysis.

Abstract Context The factors that determine the recycling of free fatty acids (FFA) back into different adipose tissue depots via the direct storage pathway are not completely understood. Objective To assess the interactions between adipocyte factors and plasma FFA concentrations that determine regional FFA storage rates. Design We measured direct adipose tissue FFA storage rates before and after weight loss under high FFA (intravenous somatostatin and epinephrine) and low (intravenous insulin and glucose) FFA concentrations. Setting Mayo Clinic Clinical Research Unit. Patients Sixteen premenopausal women, body mass index 30 to 37 kg/m2. Intervention Comprehensive lifestyle weight loss program. Main Outcome Measure Direct FFA storage rates in upper and lower body subcutaneous fat. Results Over the entire range of FFA and under isolated conditions of elevated FFA concentrations, the storage rates of FFA into upper and lower body subcutaneous fat per unit lipid were associated with concentrations, not adipocyte fatty acid storage factors. Under low FFA conditions, direct FFA storage rates were related to adipocyte CD36 content, not tissue level content of fatty acid storage factors. Weight loss did not change these relationships. Conclusions The regulation of direct FFA storage under low FFA concentration conditions appears to be at the level of the cell/adipocyte content of CD36, whereas under high FFA concentration conditions, direct FFA storage at the tissue level is predicted by plasma FFA concentrations, independent of adipocyte size or fatty acid storage factors. These observations offer novel insights into how adipose tissue regulates direct FFA storage in humans.

Introduction: Obesity is linked with heightened vulnerability to cardiovascular diseases including hypertension. Nonetheless, mechanistic studies addressing the effects of experimental weight gain on blood pressure are lacking. We sought to examine whether experimental weight gain raises ambulatory blood pressure in healthy individuals and identify any relationship between changes in blood pressure and changes in regional fat distribution. Methods: Twenty-six normal weight subjects were randomized to a 8-week period of weight gain through overfeeding (N=16; age 30.4±6.6 years, BMI 23.5±3.5 kg/m 2 ) or weight maintenance (N=10; age 27.1±7.7 years, BMI 23.6±2.7 kg/m 2 ). Measurements of body composition by dual-energy X-ray absorptiometry and abdominal computed tomographic scans and 24-h ambulatory blood pressure monitoring were obtained at baseline and at follow-up. Results: Overfeeding resulted in an increase in body weight of 3.7±1.5 kg ( p <0.001) in weight gainers, with increments seen in total (21994±8247.4 to 25180.7±8563.1 gr, p <0.001), visceral (61.6±32.7 to 75.5±30.9 cm 2 , p =0.002) and subcutaneous fat (135.5±77.4 to 167.9±82.9 cm 2 , p <0.001). No changes occurred in the maintenance group. Weight gainers exhibited an increase in 24-h systolic blood pressure at follow-up (113.7±8 to 117.7±7.9 mmHg, p =0.009) and mean blood pressure (MAP) (85.1±4.9 to 86.8±5.1 mmHg, p =0.02), while blood pressure was unchanged in controls. Changes in MAP were positively correlated only with changes in visceral fat (rho=0.452, p =0.02) but not with changes in weight or any other body composition measure. Conclusion: Modest weight gain leads to marked elevation in 24-h blood pressure in lean healthy subjects. The association between increased MAP and abdominal visceral fat accumulation suggests that visceral deposition of adipose tissue may contribute specifically and mechanistically to the enhanced risk of hypertension associated with weight gain.

Background: Endothelial dysfunction assessed by flow mediated dilation (FMD) of the brachial artery has been identified as an independent predictor of cardiovascular events. However, whether weight gain impairs endothelial function is unknown. Methods: A randomized blinded controlled-trial to assess the effects of weight gain on endothelial function. After a weight maintenance period supervised by an experience dietitian, volunteers were randomized to gain weight (4 kg) or maintain weight. We recruited lean (BMI 18.5–24.9 kg/m 2 ) healthy volunteers (no diseases, medications and non-smokers) from the community. Using ultrasound, endothelial function was measured by FMD and non-flow mediated dilation (NFMD) of the brachial artery in the early morning (6:30 a.m.). Endothelial function was measured at baseline, after fat gain at 8 weeks and after weight loss at 16 weeks for fat-gainers and at baseline and follow-up (8 weeks) for weight maintainers. Body composition techniques to measure body fat %, such as dual x-ray absorptiometry and abdominal CT scans were performed. Results: We recruited 35 fat-gainers and 8 weight maintainers. Mean age was 29 ± 6 years and 18 (42 %) were women. There were no differences in age, anthropometric and body composition measurements, blood pressure, heart rate or apnea hypopnea index at baseline between both groups. After an average gain of 4 kg, the fat-gainer group significantly increased their total, visceral and subcutaneous fat. Brachial artery FMD and NFMD remained unchanged in weight maintainers. However, it decreaed in fat-gainers (FMD=9.1 ± 3 vs. 7.6 ± 3.2, p=0.003 and NFMD=12.0 ± 4.9 vs. 10.1 ± 6.0, p=0.01), but recovered to baseline after subjects shed the gained weight (basleline vs. recovery: FMD=9.1 ± 3 vs. 9.0 ± 3, p=NS and NFMD =12.0 ± 4.9 vs.12.6 ± 5.0, p=NS). Visceral fat gain, but not subcutaneous fat gain was significantly correlated with the decrease in brachial artery FMD (rho =−0.42, p=0.004 and rho =−0.22, p=0.15, respectively). Conclusions: In lean healthy young subjects, modest weight gain results in impaired endothelial function, even in the absence of changes in blood pressure. Endothelial funcion recovers after weight loss. Viscerar rather than subcutaneous fat predicts endothelial dysfunction.

Background Increases in circulating free‐fatty acids (FFAs) contribute to obesity‐associated cardiometabolic pathology and may be considered a surrogate marker for adipose tissue dysfunction. However, alterations in FFA metabolism resulting from modest weight gain have not been previously evaluated. Objective Examine the changes in FFAs during modest weight gain in healthy individuals and to investigate the relationship between regional fat depots. Study Design We evaluated the effects of overfeeding in 8 healthy, non‐obese participants (4 men; age 29 ± 5.7 years; BMI: 25.1 ± 2.1 kg/m2). FFA concentrations were measured using liquid chromatography/mass spectrometry under fasting conditions and during oral‐glucose tolerance test (OGTT) at baseline and after 8 weeks of weight gain. Prior to the baseline and weight gain visits, subjects consumed isocaloric macro‐nutrient stable diet for three days (50% carbohydrate, 35% fat and 15% protein). Body composition and regional fat depots were assessed using dual‐energy X‐ray absorptiometry and abdominal computed tomography scans. Results Overfeeding was accompanied by 3.9 ± 1.6 kg weight gain (p=0.01) resulting from 2.9 ± 0.9 kg (p=0.01) increase in fat mass and 1.0 ± 0.9 kg (p=0.04) increase in fat‐free mass. Compared to baseline, fasting FFA (439 ± 162 μM vs. 368 ± 123 μM, p=0.55) and area under the curve (AUC) for FFA during OGTT (23319 ± 11686 μM. min−1 vs. 20495 ± 4847 μM.min−1, p=0.55) did not change with weight gain. However, at 120 min. of the OGTT FFA were significantly greater after weight gain (60 ± 18 μM vs. 77 ± 34 μM, p=0.04). We found a negative relationship between relative changes in visceral fat area and FFA at 120 min of glucose challenge (rho=−0.76, p=0.03). Furthermore, relative changes in fasting FFA and AUC for FFA during OGTT with weight gain were associated with baseline total fat mass (fasting FFA: rho=0.76, p=0.03; AUC FFA: rho=0.81; p=0.02) and baseline abdominal fat area (fasting FFA: rho=0.76, p=0.03; AUC FFA: rho=0.79; p=0.02). Conclusions Modest weight gain does not alter fasting FFA or overall FFA response to oral glucose challenge. However, our data suggest development of early stages of adipose tissue insulin resistance which is apparent via lesser suppression of FFA at 120 min. of OGTT. Furthermore, the relationships between fasting FFA, AUC‐FFA, and baseline fat mass suggest that individuals with high baseline adiposity may be more susceptible to develop adipose tissue insulin resistance with weight gain. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .