Kuniyoshi, Fatima H. Sert

Introduction: Growing evidence suggests that aberrant sleep architecture is linked to heightened risk of cardiovascular disease independently of sleep apnea. Rapid Eye Movement (REM) sleep is characterized by increased sympathetic activity and blood pressure (BP) compared to non-REM sleep stages. However, whether REM sleep is associated with BP across the 24 hours has not been investigated. Hypothesis: We hypothesized that increased REM sleep would be associated with higher ambulatory BP. Methods: We recruited 137 individuals (58% men, aged 39±14 years, office systolic/diastolic BP [SBP/DBP] 125±14/77±11 mmHg) who completed overnight polysomnography followed by 24-h ambulatory BP monitoring. Sleep was scored according to standard criteria. 24-h, daytime, and nighttime averages were calculated for SBP, DBP and heart rate. REM sleep duration was computed as percentage of total sleep time and used to group participants into tertiles as follows: T1 (REM% ≤18.8), T2 (REM% 18.9-24), and T3 (REM% ≥24.1). Results: Sex ratio, body mass index, and apnea-hypopnea index were similar across REM tertiles, but age increased with increasing tertiles (p=0.029). 24-h SBP (T1 vs T2 vs T3: 121±12 vs 117±7 vs 124±12 mmHg, p=0.015) and DBP (72±7 vs 70±6 vs 76±8 mmHg, p<0.001) differed across REM sleep tertiles, with significantly higher values in those in the highest tertile. Results were consistent when considering daytime SBP (T1 vs T2 vs T3: 126±12 vs 122±8 vs 132±14 mmHg, p<0.001) and DBP (77±7 vs 76±6 vs 83±9 mmHg, p<0.001), and nighttime DBP (65±9 vs 61±7 vs 65±8 mmHg, p=0.047). No differences were noted on nighttime SBP or any heart rate measures. A significant interaction was found between hypertension status and REM sleep in multiple regression analysis, with the observed associations being significant only among hypertensives (n=69). In those with hypertension, REM sleep duration was associated with 24-h mean BP independently of age, sex, body mass index, apnea-hypopnea index and antihypertensive medications (standardized beta 0.22, p=0.041). Conclusions: Longer REM sleep duration is independently associated with elevated ambulatory BP in individuals with hypertension. REM sleep may be a novel cardiovascular risk indicator in this population.

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.

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 Acute cardiac and vascular events, including myocardial infarction (MI) exhibit a peak onset between 6 AM and 11 AM. Plasminogen activator inhibitor‐1 (PAI‐1) is a main inhibitor of tissue‐plasminogen activator and a key indicator of prothrombotic state. Elevated levels of PAI‐1 have been linked to increased cardiac and vascular risk. Obstructive sleep apnea (OSA) has also been associated with increased risk of MI. Hypoxemia, as well as OSA, increase PAI‐1. We tested the hypothesis that the early morning after awakening is associated with higher PAI‐1 activity in subjects with acute MI who also have OSA. Methods We studied 56 subjects after acute myocardial infarction (mean age 60±2 years; BMI 28±1 kg/m 2 ). All subjects underwent complete overnight sleep polysomnography within 2 weeks after MI to assess for presence and severity of OSA. PAI‐1 activity was measured in all 56 subjects, first before sleep (at 9 PM), and then immediately after awakening in the morning (at 6 AM). A third measurement of PAI‐1 was obtained in all subjects at 11 AM. Results For the group, PAI‐1 activity almost doubled from 12.5±1.6 U/mL at 9 PM to 22.5±2.5 U/mL after waking at 6 AM and decreased to 14.2±2.4 U/mL by 11 AM (P<0.0001). Fifty seven percent of patients were observed to have OSA, with apnea hypopnea index of >10 events/hour. Sleep apnea did not contribute to further elevation of morning PAI‐1 activity level in acute MI patients (9 PM, 6 AM and 11 AM PAI‐1 activity respectively: no OSA 11.6±2.5 U/mL, 24.1±3.8 U/mL and 15.2±3.5 U/mL; OSA 13.3±2.1 U/mL, 21.1±3.3 U/mL and 13.3±3.3 U/mL; P=0.8 for between group comparison). Conclusions Increased PAI‐1 activity in acute MI patients may be an important mechanism underlying the early morning peak in cardiovascular events. The presence of OSA however does not appear to further accentuate the already elevated PAI‐1 activity in acute MI patients. In patients after acute MI, the diurnal variation in PAI‐1, rather than apnea, may drive the impaired fibrinolysis. Support or Funding Information ‐‐R01 grant HL65176‐‐This study was also supported in part by a gift to the Mayo Foundation by the Philips Respironics Foundation. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Background Expression of adiponectin, an anti‐atherogenic and insulin‐sensitizing adipokine, is decreased in obesity. Mechanisms underlying this reduction are not well understood. Increased adiponectin in obesity may protect against development of cardiac and metabolic disorders. Objective To investigate the role of leptin in regulating adiponectin expression in humans. Design 1) determining the relationship between leptin and adiponectin in healthy humans during modest weight gain; 2) in‐vitro validation of the role of leptin in adiponectin expression. Results Modest weight gain of 3.8 ± 1.2 kg over 8 weeks of overfeeding in normal weight healthy subjects (n=33, 22 men, 30±7 years) increased both leptin and adiponectin. Changes in leptin during weight gain correlated with changes in adiponectin (rho=0.35, p=0.045), suggesting that leptin may regulate adiponectin expression. In cultured differentiated human white preadipocytes, leptin increased adiponectin mRNA and protein expression. Conclusions Leptin induces adiponectin expression. In obesity, adipose tissue may be resistant to leptin signaling thus preventing increases in adiponectin. Therefore, impaired leptin signaling may contribute to low adiponectin in obesity. Targeting leptin resistance may be beneficial in preventing obesity‐associated cardiac and metabolic disorders. Support : AHA 11SDG7260046, R21 DK81014

Background: Decreased testosterone (TTST) and sex hormone binding globin (SHBG) contribute to development of cardiometabolic disorders in obese men. We aimed to determine the effect of weight gain and weight loss on TTST and SHBG in healthy men and to examine their relationship with endothelial function. Method: 25 normal weight healthy men underwent an overfeeding protocol to gain 5% body weight over 8 weeks. Following weight gain, they underwent 8 weeks of weight loss. TTST, SHBG and endothelial function (brachial artery flow‐mediated dilation, FMD) were measured at baseline (T1), after weight gain (T2) and after weight loss (T3). Results: Volunteers gained 4 ± 1.3 kg and subsequently lost 3.2 ± 1.5 kg of body weight. TTST levels did not change (T1: 18.85 ± 6.2 nmol/L, T2: 19.3 ± 6.9 nmol/L, T3: 20.3 ± 7.6 nmol/L). However, SHBG decreased during weight gain (p=0.04) and increased during weight loss (p=0.0005) (T1: 22.8 ± 10.5 nmol/L, T2: 20.8 ± 11.1 nmol/L, T3: 25.58 ± 11.5 nmol/L). Furthermore, SHBG reduction during weight gain tended to correlate with decreases in FMD (p=0.06; R 2 =0.15). During weight loss, increases in SHBG correlate negatively with changes in FMD (p=0.008; R 2 =0.32). Conclusion : In normal weight healthy men, SHBG decreases with modest weight gain and increases with weight loss. TTST does not change. Changes in SHBG partly predict improvements in endothelial function with weight loss. Grant Funding Source : Supported by AHA 11SDG7260046, R21 DK81014, AHA 13POST16420009

Background: Abdominal fat elevates while lower-body (LB) fat diminishes cardiovascular risk. However, molecular mechanisms differentiating the two fat depots are not completely understood. MicroRNA (miRNA) are important regulators of gene expression with widespread effects on several proteins. Objective: To explore miRNA differences between the two fat depots using unbiased next-generation sequencing (NGS) approach. Methods: Total RNA isolated from paired subcutaneous (sc) fat tissue obtained from abdomen (ABD) and LB (femoral) region of 12 healthy subjects (7 male; age: 27 ± 5 years; BMI: 23.5 ± 3.2 kg/m 2 ) was used to quantify miRNA expression. Body fat distribution was determined using dual-energy X-ray absorptiometry and abdominal computed tomography scans. RNA was prepped using the NEBNext small RNA library prep kit and sequenced using Illumina HiSeq 2000. Raw sequence data were processed using CAP-miRSeq pipeline. miRNA expression between the two depots was evaluated using EdgeR. Relationship between miRNA and regional fat depots were examined using Spearman’s correlation. Adjusted or unadjusted P value <0.05 was considered significant. Results: Using NGS, 383 ± 55 known miRNA with ≥5 raw reads were detected in the study samples. Principal component analysis including all miRNAs showed no any clear separation between ABD or LB fat tissue. However, 37 miRNAs were found to have altered expression in the two depots. miR-196a-5p (log2FC=1.138, p<0.001), miR-146b-5p ( log2FC=1.388, p<0.001), miR-1287 ( log2FC=1.059, p<0.001), miR-1247-5p (1.002, p<0.001), and miR-346 (log2FC =-1.240, p=0.002) were among the top five differentially expressed miRNA in ABD Vs. LB fat. Interestingly, ABD fat tissue expression of miR196a-5p (rho=-0.58, p=0.047) and miR146b-5p (rho=0.76, p=0.004) correlated with visceral fat while miR146b-5p (rho=0.66, p=0.02) and miR1287 (rho=0.79, p=0.002) correlated with ABD sc fat. Conclusions: Several miRNAs are differentially expressed between ABD and LB fat tissue which may partly contribute to depot specific alterations in adipose tissue function and consequent cardiometabolic risk. Furthermore, the associations between miRNA and regional fat depots suggest a functional role of these miRNA in fat distribution.