Insufficient sleep is associated with a pro-atherogenic circulating microRNA signature.

NEW FINDINGS: What is the central question of the study Is habitual short sleep associated with altered circulating levels of specific inflammation- and vascular-related microRNAs? What is the main finding and its importance? Circulating levels of miR-125a, miR-126 and miR-146a were significantly lower in the short sleep compared with the normal sleep group. Altered circulating profiles of these vascular-related microRNAs have been linked to vascular inflammation, dysfunction and increased cardiovascular disease events. Sleep-related changes in these microRNAs are consistent with, and might play a role in, the aberrant vascular physiology and increased vascular risk associated with short sleep. ABSTRACT: Habitual short sleep duration (<7 h night-1 ) is associated with increased morbidity and mortality attributable, in large part, to increased inflammatory burden and endothelial dysfunction. MicroRNAs (miRNAs) play a key role in regulating vascular health, and circulating levels are now recognized to be sensitive and specific biomarkers of cardiovascular function, inflammation and disease.  The aim of this study was to determine whether the expression of circulating miR-34a, miR-92a, miR-125a, miR-126, miR-145, miR-146a and miR-150 is disrupted in adults who habitually sleep <7 h night-1 (short sleep). These were chosen based upon their well-established links with vascular inflammation, function and, in turn, cardiovascular risk. Twenty-four adults were studied: 12 with normal nightly sleep duration (six men and six women; age, 55 ± 3 years old; sleep duration, ≥7.0 h night-1 ) and 12 with short nightly sleep duration (seven men and five women; 55 ± 2 years old; sleep duration, <7 h night-1 ), and circulating miRNA expression was assayed by RT-PCR. All subjects were non-smokers, normolipidaemic, non-medicated and free of overt cardiovascular disease. Circulating levels of miR-125a (3.07 ± 1.98 versus 7.34 ± 5.34 a.u.), miR-126 [1.28 (0.42-2.51) versus 1.78 (1.29-4.80) a.u.] and miR-146a [2.55 (1.00-4.80) versus 6.46 (1.50-11.44) a.u.] were significantly lower (∼60, 40 and 60%, respectively) in the short compared with the normal sleep group. However, there were no significant group differences in circulating levels of miR-34a, miR-92a, miR-145 and miR-150. In summary, chronic short sleep is associated with a marked reduction in circulating levels of miR-125a, miR-126 and miR-146a. Dysregulation of these miRNAs might contribute to the increased inflammatory burden and endothelial dysfunction associated with habitual insufficient sleep.

Influence of sex on the number of circulating endothelial microparticles and microRNA expression in middle-aged adults.

NEW FINDINGS: What is the central question of this study? Are there sex-related differences in the number of circulating endothelial microparticles (EMPs) and microparticle microRNA expression in middle-aged adult humans? What is the main finding and its importance? Although the numbers of circulating endothelial microparticles do not differ between middle-aged men and women, there are sex-related differences in the expression of miR-125a in activation-derived EMPs and miR-34a in apoptosis-derived EMPs. Differences in circulating endothelial microparticle microRNA content may provide new insight into the sex-related disparity in the risk and prevalence of vascular disease in middle-aged adults. The aims of this study were to determine: (i) whether circulating concentrations of endothelial microparticles (EMPs) differ in middle-aged men compared with women; and (ii) whether there are sex-related differences in microRNA expression in EMPs. Peripheral blood was collected from 30 sedentary adults: 15 men (56 ± 6 years old) and 15 women (56 ± 5 years old). Endothelial microparticles were defined by markers of activation (CD62e+ ) or apoptosis (CD31+ /CD42b- ) by flow cytometry. Expression of microRNA (miR-34a, 92a, 125a and 126) in activation- and apoptosis-derived EMPs was measured by RT-PCR. Circulating activation- (33 ± 31 versus 39 ± 35 microparticles µl-1 ) and apoptosis-derived EMPs (49 ± 54 versus 42 ± 43 microparticles µl-1 ) were not significantly different between men and women. Expression of miR-125a (2.23 ± 2.01 versus 6.95 ± 3.99 a.u.) was lower (∼215%; P < 0.05) in activation-derived EMPs, whereas expression of miR-34a (1.17 ± 1.43 versus 0.38 ± 0.35 a.u.) was higher (∼210%; P < 0.05) in apoptosis-derived EMPs from men compared with women. Expression of microRNA in circulating EMPs may provide new insight into sex-related differences in cardiovascular disease.

Influence of Overweight and Obesity on Circulating Inflammation-Related microRNA.

BACKGROUND: Increased cardiovascular disease risk and prevalence associated with overweight and obesity is due, in part, to heightened inflammatory burden. The mechanisms underlying adiposity-related amplification of inflammation are not fully understood. Alterations in regulators of inflammatory processes such as microRNAs (miRs), however, are thought to play a pivotal role. OBJECTIVE: The aim of this study was to determine the influence of overweight and obesity, independent of other cardiovascular risk factors, on circulating expression of miR-34a, miR-126, miR-146a, miR-150 and miR-181b. METHODS: Forty-five sedentary, middle-aged (47-64 years) adults were studied: 15 were normal weight (8M/7F; BMI: 23.3 ± 0.3 kg/m2); 15 were overweight (8M/7F; 28.2 ± 0.3 kg/m2); and 15 were obese (7M/8F; 32.3 ± 0.5 kg/m2). All subjects were non-smokers, normotensive and free of overt cardiometabolic disease. Circulating levels of the following inflammation-related miRs: miR-34a, miR-126, miR-146a, miR-150 and miR-181b were determined in plasma using standard RT-PCR techniques. miR expression was normalized to exogenous C. elegans miR-39 and reported as relative expression (AU). RESULTS: Circulating miR-34a was ~200% higher (P< 0.05) in the obese as compared with normal weight and overweight groups. Whereas, miR-126, miR-146a and miR-150 were significantly lower (~65%) in both the obese and overweight groups than the normal weight group. There were no significant group differences in circulating expression of miR-181b. miR-34a was positively related (r = 0.43; P< 0.05); whereas, miR-126 (r = -0.48), miR-146a (r = -0.33) and miR-150 (r = -0.43) levels were significantly inversely related to BMI. CONCLUSION: Overweight and obesity, independent of other cardiometabolic risk factors, negatively influences circulating inflammation-related miRs. Dysregulation of circulating miRs may contribute mechanistically to the heightened inflammatory state associated with overweight and obesity.

Association between hypertension and circulating vascular-related microRNAs.

microRNAs (miRNAs) have a key role in regulating inflammation, vascular health and in turn, cardiovascular disease. Specifically, altered circulating expression of miR-17, miR-21, miR-34a, miR-92a, miR-126, miR-145, miR-146a, and miR-150 has been linked with the pathogenesis and progression of cardiovascular disease. The aim of this study was to determine whether the circulating profile of these vascular-related miRNAs is disrupted with hypertension. Thirty sedentary, middle-aged adults were studied: 15 normotensive (10M/5F; age: 56 ± 1 year; BP: 113/71 ± 2/1 mmHg) and 15 hypertensive (10M/5F; 56 ± 2 year; 140/87 ± 2/2 mmHg). All subjects were non-obese and free of other cardiometabolic disorders. Circulating miRNAs were determined in plasma using standard RT-PCR techniques with miRNA primers of interest. Expression was normalized to exogenous C. elegans miR-39 and reported as relative expression in arbitrary units (AU). Circulating expression of miR-34a (9.18 ± 0.94 vs 5.33 ± 0.91 AU) was higher (~170%; P < 0.01) whereas the expression of miR-21 (1.32 ± 0.25 vs 2.50 ± 0.29 AU), miR-126 (0.85 ± 0.10 vs 1.74 ± 0.27 AU) and miR-146a (1.50 ± 0.20 vs 3.10 ± 0.50 AU) were markedly lower (~50%, ~55%, and ~55% respectively; P < 0.05) in the hypertensive vs normotensive groups. Moreover, circulating levels of miR-34a, miR-21, and miR-126 were significantly related to systolic blood pressure (r = 0.48, r = -0.38; r = -0.48); whereas, miR-146a was significantly related to both systolic (r = -0.58) and diastolic (r = -0.55) blood pressure. There were no significant group differences in circulating miR-17, miR-92a, miR-145, and miR-150. In summary, these results suggest that hypertension, independent of other cardiometabolic risk factors, adversely affects the circulating profile of a subset of vascular-related miRNAs that have been link to CVD risk and development.

Endothelial vasodilator function in normal-weight adults with metabolic syndrome.

Metabolic syndrome (MetS) typically presents with obesity; however, obesity is not a requisite characteristic for MetS classification and related vascular risk. We tested the hypothesis that MetS, independent of excess adiposity, is associated with impaired endothelial vasodilator dysfunction. Thirty-two sedentary, middle-aged adults were studied: 11 normal weight (9 male and 2 female; body mass index (BMI), 24.0 ± 0.3 kg/m2); 11 normal weight with MetS (9 male and 2 female; BMI, 24.7 ± 0.3 kg/m2); and 10 obese without MetS (8 male and 2 female; BMI, 31.4 ± 0.5 kg/m2). MetS was established according to National Cholesterol Education Program Adult Treatment Panel III criteria. Forearm blood flow (FBF) responses to intra-arterial infusions of acetylcholine and sodium nitroprusside were measured via strain-gauge plethysmography. FBF responses to acetylcholine were ∼20% lower (P < 0.05) in the normal-weight subjects with MetS (from 4.0 ± 0.3 to 13.0 ± 1.0 mL/(100 mL tissue·min)) and obese subjects (from 4.8 ± 0.2 to 12.2 ± 1.1 mL/(100 mL tissue·min)) compared with the normal-weight subjects (from 4.6 ± 0.4 to 15.8 ± 0.7 mL/(100 mL tissue·min)). Of note, FBF responses to acetylcholine were similar between the normal-weight adults with MetS and the obese adults. There were no differences among groups in FBF response to sodium nitroprusside. These data indicate that the presence of MetS, independent of obesity, is associated with diminished endothelium-dependent vasodilation. Endothelial vasodilator dysfunction may underlie the increased cardiovascular risk in normal-weight adults with MetS.

Elevations in C-reactive protein and endothelin-1 system activity in humans.

AIMS: C-reactive protein (CRP) is an inflammatory cytokine that has been shown to be an independent predictor of future atherothrombotic events. Hyperactivity of endothelin-1 (ET-1), a potent vasoconstrictor peptide produced by the endothelium, is linked with cardiovascular disease development and progression. ET-1 is sensitive to inflammatory stimuli, though the influence of CRP on ET-1 system activity is unknown. We tested the hypothesis that ET-1-mediated vasoconstrictor tone is enhanced in adults with elevated plasma CRP concentrations. MATERIALS AND METHODS: Sixty non-obese adults (43-70years) were studied: 20 with hsCRP<1.0mg/L (low CRP; 0.5±0.1mg/L); 20 with hsCRP 1.0-3.0mg/L (moderate CRP; 2.0±0.1mg/L); and 20 with hsCRP>3.0mg/L (high CRP; 6.3±0.5mg/L). Forearm blood flow (FBF; plethysmography) was determined in response to intra-arterial infusions of ET-1 (5pmol/min for 20min) and selective ETA receptor blockade (BQ-123, 100nmol/min for 60min). KEY FINDINGS: In response to ET-1, FBF decreased ~10% in the low (-10.0±2.3%), moderate (-10.7±4.0%), and high (-6.6±5.2%) CRP groups, with no significant differences between groups. Additionally, all groups demonstrated a marginal, though significant (~10%), vasodilator response to BQ-123; however, there were no differences in the FBF response to BQ-123 across CRP groups. There were no significant correlations between plasma CRP concentrations and peak FBF response to either ET-1 or BQ-123. SIGNIFICANCE: These results indicate that ET-1 system activity is not influenced by elevations in CRP. Enhanced ET-1 system activity may not be involved in the increased cardiovascular disease risk associated with elevations in plasma CRP concentrations.