Somers, Virend K.

Background: Leptin contributes to obesity-related cardiometabolic pathology. While the role of adipose tissue dysfunction in altering metabolic profile in obesity is recognized, the direct effects of leptin signaling in adipose tissue are not completely understood. Among factors impacting adipose tissue function in obesity, adipocyte death is associated with increased inflammation with consequent adipose tissue insulin-resistance. Furthermore, apoptosis of adipocyte progenitor cells (preadipocytes) is important as it lowers adipose tissue capacity to maintain and expand fat storage. Objective: To determine the effects of leptin on regulation of proteins important to apoptotic pathways in cultured human white preadipocytes (HWP) and differentiated HWP (dHWP). Methods: Cells were exposed to increasing concentrations of leptin to evaluate the role of leptin on regulation of anti-apoptotic Bcl2, and pro-apoptotic Bax and CD95 expression. Next, we examined if pre-exposure to leptin attenuated TNF-α and FasL induced apoptosis. Results: Leptin upregulated transcription of Bcl2 (p=0.02) and down-regulated transcription of Bax (p=0.02) and CD95 (p=0.04) in a leptin-concentration dependent manner in dHWP. Leptin dependent increases in Bcl2 (p=0.004) and decreases in Bax (p=0.003) and CD95 (P=0.03) protein expression were also observed. Furthermore, 24 hour pre-exposure to leptin protected cells from TNF-α (p=0.01; p=0.006) and FasL (p=0.03; p=0.007) induced apoptosis in dHWP and HWP respectively. Additionally, leptin attenuated TNF-mediated activation of the p53 pathway, suggesting another mechanism by which leptin mediates its inhibitory effects on TNF-induced apoptosis. Conclusion: Leptin regulates the expression of proteins involved in the apoptotic pathway such that it decreases the apoptotic potential of adipose tissue by increasing anti-apoptotic Bcl2 and decreasing pro-apoptotic Bax and CD95 protein expression. In contrast to our in-vitro findings, prior studies in adipose tissue from obese humans report decreased Bcl2 and increased Bax protein expression, along with high leptin expression. This suggests that increased adipose tissue apoptosis in obesity may at least in part be secondary to altered leptin signaling.

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.

Background The prognostic significance of obstructive sleep apnea ( OSA ) in patients with acute coronary syndrome ( ACS ) in the contemporary era is unclear. We performed a large, prospective cohort study and did a landmark analysis to delineate the association of OSA with subsequent cardiovascular events after ACS onset. Methods and Results Between June 2015 and May 2017, consecutive eligible patients admitted for ACS underwent cardiorespiratory polygraphy during hospitalization. OSA was defined as an apnea‐hypopnea index ≥15 events·h −1 . The primary end point was major adverse cardiovascular and cerebrovascular event ( MACCE ), including cardiovascular death, myocardial infarction, stroke, ischemia‐driven revascularization, or hospitalization for unstable angina or heart failure. OSA was present in 403 of 804 (50.1%) patients. During median follow‐up of 1 year, cumulative incidence of MACCE was significantly higher in the OSA group than in the non‐ OSA group (log‐rank, P =0.041). Multivariate analysis showed that OSA was nominally associated with incidence of MACCE (adjusted hazard ratio, 1.55; 95% CI, 0.94–2.57; P =0.085). In the landmark analysis, patients with OSA had 3.9 times the risk of incurring a MACCE after 1 year (adjusted hazard ratio, 3.87; 95% CI, 1.20–12.46; P =0.023), but no increased risk was found within 1‐year follow‐up (adjusted hazard ratio, 1.18; 95% CI, 0.67–2.09; P =0.575). No significant differences were found in the incidence of cardiovascular death, myocardial infarction, and ischemia‐driven revascularization, except for a higher rate of hospitalization for unstable angina in the OSA group than in the non‐ OSA group (adjusted hazard ratio, 2.10; 95% CI, 1.09–4.05; P =0.027). Conclusions There was no independent correlation between OSA and 1‐year MACCE after ACS . The increased risk associated with OSA was only observed after 1‐year follow‐up. Efficacy of OSA treatment as secondary prevention after ACS requires further investigation.

SummaryObjectiveWe aimed to determine the frequency of probable obstructive sleep apnea (pOSA) in refractory epilepsy monitoring unit inpatients and clinical features associated with pOSA, including risk for sudden unexpected death in epilepsy (SUDEP).MethodsWe prospectively recruited 49 consecutive adult patients admitted to the Mayo Clinic Epilepsy Monitoring Unit with focal, generalized, or unclassified epilepsy syndromes. pOSA was identified using oximetric oxyhemoglobin desaturation index (ODI) and the Sleep Apnea–Sleep Disorders Questionnaire (SA‐SDQ) and STOP‐BAG screening tools. Revised SUDEP Risk Inventory (rSUDEP‐7) scores were calculated, and epilepsy patients with and without pOSA were compared with Wilcoxon signed‐rank tests. Correlation and regression analyses were utilized to determine relationships between pOSA and rSUDEP‐7 scores.ResultsThirty‐five percent of patients had pOSA, with a mean ODI of 11.3 ± 5.1/h (range = 5.1‐22.8). Patients with pOSA were older and heavier, and more frequently had a focal epilepsy syndrome and longer epilepsy duration, with higher SA‐SDQ and STOP‐BAG scores (all P < 0.05). Median rSUDEP‐7 score was 3 ± 1.4 (range = 0‐6). Higher rSUDEP‐7 scores were positively correlated with higher ODI (P = 0.036). rSUDEP‐7 score ≥ 5 was associated with pOSA by ODI, SA‐SDQ, and STOP‐BAG questionnaire criteria (P < 0.05).SignificanceOur pilot study identified a high frequency of pOSA in refractory epilepsy monitoring patients, finding that pOSA patients were older and heavier, with higher screening symptoms for sleep apnea and more frequent focal seizures with a longer epilepsy duration. We also found a possible association between OSA and SUDEP risk. Identification and treatment of OSA in patients with epilepsy could conceivably provide a novel approach toward preventing the risk of SUDEP. Future studies with polysomnography are needed to confirm predictive features for OSA in epilepsy populations, and to determine whether OSA is associated with SUDEP risk.

Extremes of sleep duration and obstructive sleep apnea (OSA) are both associated with hypertension. We aimed to explore whether sleep duration modifies the relationship between OSA and prevalent hypertension, using both objective and subjective measures of total sleep duration. A total of 7107 OSA patients and 1118 primary snorers were included in the study. Hypertension was defined based either on direct blood pressure measures or on diagnosis by a physician. Objective sleep duration was derived by polysomnography and subjective sleep duration was self-reported. Logistic regression models were used to estimate the associations between objective/subjective sleep duration and hypertension prevalence in OSA and primary snorers. Compared with primary snorers, OSA combined with objective sleep duration of 5 to 6 hours increased the odds of hypertension by 45% (odds ratio, 1.45; 95% confidence interval, 1.14–1.84), whereas OSA combined with objective sleep duration <5 hours further increased the odds of hypertension by 80% (odds ratio, 1.80; 95% confidence interval, 1.33–2.42). These results were independent of major confounding factors frequently associated with OSA or hypertension. In stratified analysis by sleep duration, risk of hypertension in those with extremely short sleep (<5 hours) was not significantly different between OSA and primary snorers, whereas odds were significant for OSA in the other 4 sleep duration strata (5–6, 6–7, 7–8, and >8 hours). No significance was evident using subjective sleep duration. We conclude that objective short sleep duration is associated with hypertension in OSA patients. Extremely short sleep duration in itself may actually be even more detrimental than OSA in terms of hypertension risk.

It has been postulated that catheter-based renal denervation (RDN) may lower blood pressure (BP) and improve severity of obstructive sleep apnea (OSA) in resistant hypertensive patients. The aim of our study (NCT01366625) was to investigate in a prospective randomized trial the effect of RDN on BP and clinical course of OSA. Sixty patients with true resistant hypertension coexisting with moderate-to-severe OSA (apnea/hypopnea index, ≥15) were randomly allocated to RDN group (30 patients) and to control group (30 patients). The primary end point was reduction in office systolic BP at 3 months. Secondary end points included reduction in diastolic office and ambulatory BP, change in apnea/hypopnea index and biochemical measurements at 3 months, and change in echocardiographic measurements at 6 months. There were no differences in clinical characteristics between the groups. At 3 months in the RDN group, both office and ambulatory BP were significantly reduced, and a significant decrease in OSA severity (apnea/hypopnea index, 39.4 versus 31.2 events per hour; P =0.015) was observed. Between-group difference in apnea/hypopnea index change was significant at 0.05. At 6 months in the RDN group, reductions in office and ambulatory BP were sustained and were accompanied by significant improvement in echocardiographic measures of global longitudinal strain. There were no differences in metabolic variables in follow-up in both groups. In a randomized controlled trial, RDN lowered both office and ambulatory BP in patients with resistant hypertension and OSA. This was accompanied by improvement of the clinical severity of OSA. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01366625.