Citations

Background Obesity‐associated metabolic disorders have been shown to be related to body fat distribution. Specifically, increases in visceral fat are more detrimental than increases in subcutaneous fat depots. However, the underlying mechanisms through which visceral fat potentiates cardiometabolic dysregulation are not completely understood. In recent years, the presence of localized renin angiotensin system (RAS) in adipose tissue and its role in regulating blood pressure and metabolism has been recognized. Therefore, we investigated if differential expression of RAS components in visceral versus subcutaneous adipose tissue may help explain pathological effects of visceral fat. Hypothesis We hypothesized that compared to subcutaneous adipose tissue, visceral adipose tissue has increased expression of RAS proteins involved in the pro‐inflammatory and pro‐fibrotic ANGII‐AT1R pathway but attenuated expression of proteins mediating the anti‐inflammatory and anti‐fibrotic ANG1‐7‐MASR pathway. Methods We determined the expression of RAS proteins in paired subcutaneous and visceral (omental) adipose tissue samples from obese individuals undergoing surgery (n = 30, BMI: 46.1 ± 7.3 kg/m 2 , age: 46.5 ± 14.4 years) by Western blot. We examined proteins involved in 1) Ang II generation: angiotensinogen (AGT), angiotensin converting enzyme (ACE), chymase; 2) Ang1‐7 generation: ACE‐2; and 3) cellular receptors: angiotensin I receptor (AT1R), MAS receptor (MASR), and aldosterone receptor. Results Comparison of protein expression between subcutaneous and visceral adipose tissue samples showed no changes in proteins involved in generation of angiotensin peptides, namely AGT (0.64 ± 0.57 vs. 0.33 ± 0.28, p = 0.11, n = 12), chymase (0.27 ± 0.23 vs. 0.36 ± 0.41, p = 0.77, n = 22), and ACE‐2 (0.23 ± 0.41 vs. 0.08 ± 0.09, p = 0.21, n = 15). However, ACE expression tended to be higher in subcutaneous vs. visceral fat (0.10 ± 0.06 vs. 0.06 ± 0.03, p = 0.052, n = 12). Furthermore, expression of cellular receptor AT1R was higher in subcutaneous fat (0.24 ± 0.34 vs. 0.07 ± 0.09, p = 0.03, n = 12), and MASR was lower in subcutaneous fat (0.22 ± 0.26 vs. 0.88 ± 0.99, p = 0.01, n = 20). Aldosterone receptor expression (0.21 ± 0.22 vs. 0.14 ± 0.13, p = 0.52, n = 11) was not altered in subcutaneous and visceral depots. Conclusions Proteins involved in the generation of angiotensin peptides are not differentially expressed in subcutaneous versus visceral fat depots. However, expression of cellular receptors is different such that inflammatory and fibrotic effects of RAS may be more predominant in subcutaneous fat. Therefore, RAS is likely to play a role in limiting subcutaneous fat expansion thereby leading to increased visceral fat depots. Furthermore, our findings do not support the role of visceral RAS in development and progression of cardiovascular pathology associated with increased visceral fat depots. Support or Funding Information MAP and KRS were supported by the American Physiological Society Stride Summer Undergraduate Research Fellowship NHLBI 1 R25 HL115473‐01.

Background Obstructive sleep apnea (OSA) is characterized by repetitive intermittent hypoxia and reoxygenation during sleep, and is a risk factor for cardiometabolic diseases including hypertension and diabetes. The renin‐angiotensin system (RAS) is an important cardiovascular and metabolic regulator playing key roles via angiotensin peptides. Recent studies demonstrate that all components of the RAS, including enzymes responsible for AngII generation, such as angiotensin converting enzyme (ACE) and chymase, are present in adipose tissue. Furthermore adipose tissue significantly contributes to systemic levels of AngII, thereby potentiating development of hypertension in obesity. Given that OSA patients are mostly obese, the localized effects of RAS in adipose tissue are likely an important mediator of OSA‐related hypertension. This study sought to investigate the effects of intermittent hypoxia (IH), a hallmark of OSA, on Ang II generation pathways in preadipocytes. Methods/Results RAS plays an important role in adipose tissue via its action on preadipocytes. Therefore, we examined the effects of IH in primary cultures of human white preadipocytes (HWP). HWP cells were exposed to repeated cycles of 30 min‐21% O 2 (normoxic) and 30 min‐1% O 2 (hypoxic) at 37°C for 24 hours. Cells grown in continuous normoxic conditions were used as controls. mRNA and protein expression of ACE, chymase, renin, AT1, and AT2 receptors were investigated by semi‐quantitative RT‐PCR and Western blot, respectively. Ang II secretion was examined by enzyme‐linked immunosorbent assay in condition medium. Results IH upregulated ACE (P=0.04) and chymase (P=0.05) expression while the expression of renin (P=0.94), AT1R (P=0.30), and AT2R (P=0.58) receptors did not change in HWP. Additionally, IH increased Ang II secretion in conditioned media (P=0.01). Conclusions This is the first study to demonstrate intermittent hypoxia‐mediated upregulation of Ang II generating enzymes ACE and chymase, along with increased AngII secretion in HWP. Together, our data strongly support the role of IH in upregulating RAS via increases in AngII. These studies suggest a role for adipose tissue and RAS in OSA related pathophysiology. Support or Funding Information NIH R01 grant (#HL65176); Becari C. is supported by grant from CNPq‐Brazil (# 203802/2014‐4).

BACKGROUND Leptin is an adipokine with a central role in energy homeostasis and appetite regulation. Increases in leptin suppress appetite, while decreases in leptin increase appetite and may consequently cause weight gain. Patients with established obstructive sleep apnea (OSA) have been shown to have elevated leptin. Also, newly diagnosed OSA patients have a history of significant recent weight gain. Repetitive nocturnal intermittent hypoxia has been implicated in OSA pathophysiology and in increases in leptin. However, the factors contributing to weight gain in OSA are not completely understood. In contrast to the history of weight gain in OSA subjects, animal models of intermittent hypoxia (IH) are associated with weight loss along with increases in leptin. Furthermore, acute altitude dependent hypoxia in humans has also been associated with loss of appetite and increases in leptin. We postulated that the duration of IH may be important in defining the nature of effects on leptin. In this study we sought to examine the interactions between IH and leptin secretion, comparing acute versus chronic exposure to IH. We tested the hypothesis that although acute IH increases leptin secretion and likely suppresses appetite, repeated chronic exposure to IH will decrease leptin secretion, and thereby may increase appetite and predispose individuals such as patients with OSA to weight gain. METHODS We used an in‐vitro approach to examine the acute effects of IH (24 cycles of 30 min 0.1% O 2 followed by 30 min exposure to 21% O 2 ) in differentiated human white preadipocytes. Cells grown in normoxic conditions and continuous hypoxia were controls for these experiments. For chronic treatment, cells were exposed to 9 cycles of IH each day for 7 days. Leptin secretion was measured in 48 h conditioned media by ELISA. RESULTS Acute 24 hour exposure to IH or sustained hypoxia increased leptin secretion (p = 0.013). However, chronic 7 day exposure of differentiated human white preadipocytes caused decreases in leptin secretion (p = 0.02). CONCLUSION Acute intermittent hypoxia elicits increases in leptin secretion. Conversely, chronic IH decreases leptin secretion, suggesting a mechanism for development of obesity in the early stages of OSA. We speculate that decreased leptin, as a consequence of chronic IH, would result in increased appetite and hence weight gain. As obesity progresses, leptin levels likely rise secondary to the increase in body fat. Elevated leptin levels in patients with longstanding OSA may be indicative of increased fat mass and not a consequence of IH‐mediated effects on adipocytes. Support or Funding Information Christiane Becari was supported by a grant from CNPq Brazil (# 203802/2014‐4); Prachi Singh was supported by AHA scientist development grant (11SDG7260046).

Background Obstructive sleep apnea (OSA) patients have elevated levels of plasma leptin and are exposed to repeated nocturnal intermittent hypoxia (IH). Leptin induces increased adiponectin expression, suggesting that adiponectin should be increased in OSA. However, levels of plasma adiponectin, an anti‐atherogenic and insulin‐sensitizing adipokine, are inconsistent in OSA, and adiponectin levels are often low. Both increases in leptin and decreases in adiponectin may contribute to increased cardiometabolic risk in OSA. In this study we sought to examine the interactions between IH, leptin, and adiponectin. Using an in‐vitro approach in differentiated human white preadipocytes (dHWP), we tested the hypothesis that adiponectin expression in response to acute IH‐mediated increases in leptin may be modulated in the presence of hypoxia. Methods dHWP were exposed to 24 cycles of IH (30 min 0.1% O2 followed by 30 min exposure to 21% O2), continuous hypoxia (0.1% O2) or continuous normoxia (21% O2, control). Secretion of leptin and adiponectin in the 24h conditioned media was determined by ELISA and intracellular changes in adiponectin were determined by Western blot analysis. Results We show that acute 24 hour exposure to IH or sustained hypoxia increased leptin secretion (p = 0.013) but did not alter adiponectin secretion (p = 0.48). In fact, the intracellular expression of adiponectin actually decreased during the acute exposure to both IH and to continuous hypoxia (p = 0.02). Also, while leptin increased intracellular adiponectin expression in normoxic conditions (p = 0.03), it was unable to do so in the presence of IH and hypoxia (p = 0.36). Conclusions Acute IH and continuous hypoxia mediate increases in leptin, but not in adiponectin secretion. Furthermore, although leptin increases adiponectin in normoxic conditions, IH and continuous hypoxia cause decreases in intra‐cellular adiponectin expression and also attenuate leptin‐mediated increases in adiponectin expression. These hypoxia‐effects on adiponectin expression may help explain the low adiponectin levels in OSA, which may contribute to increased cardiovascular and diabetes risk. Support or Funding Information Christiane Becari was supported by a grant from CNPq Brazil (# 203802/2014‐4); Michaela Pfeifer was supported by the APS STRIDE summer undergraduate research fellowship (NHLBI 1R25HL115473‐01); Prachi Singh was supported by AHA scientist development grant 11SDG7260046.

Background Obstructive sleep apnea (OSA) increases the risk for metabolic and cardiovascular disease. Telomere shortening has been linked to hypertension, diabetes mellitus, and cardiovascular diseases such as stroke and myocardial infarction. Because these conditions are highly prevalent in sleep apnea, we hypothesized that telomere length (TL) would be reduced in patients with OSA. Methods Genomic DNA was isolated from circulating leukocytes in 176 subjects (42.8 ± 13.8 years, 22.7 % women) who had undergone overnight polysomnographic evaluation. Of these individuals, 92 subjects had an Apnea Hypopnea Index (AHI) >5 events/hour and were classified as OSA patients. TL was measured using a quantitative PCR where a telomere to single copy gene ratio is determined and represented as number of base pairs (bp). The effect of OSA on TL was determined by comparing a control group (no OSA) (AHI<5, n=92) with patients with mild OSA (≥ 5 AHI <15, n=25), and those with moderate to severe OSA (AHI ≥15, n=59) in unadjusted and age‐adjusted models. Results Compared to control subjects, mild and moderate to severe OSA subjects were older: 48.9 ± 11.2 vs. 36.0 ± 11.2 years (p<0.001) and 50.8 ± 13.1 vs. 36.0 ± 11.2 years (p<0.001), respectively. Statistical models examining the effects of OSA severity on TL showed a J‐shaped curve : longer TL in moderate to severe OSA (4867 ± 221 bp) and controls (4820 ± 160 bp), and the shortest TL in mild OSA (4742 ± 155 bp). The mean TL in moderate to severe OSA was significantly longer than in mild OSA (p=0.0048). These effects were more pronounced after adjustment for age, when we observed significant differences in mean TL between moderate to severe OSA and mild OSA (p=0.0036) and between moderate to severe OSA and the control group (p=0.0379) (). However, the mean TL between control subjects and subjects with mild OSA was not different. Conclusion Moderate to severe OSA patients had longer TL compared with mild OSA and control group. This association was independent of age. Even though OSA is associated with increased cardiovascular risk, telomere lengthening in subjects with moderate to severe OSA suggests the presence of protective compensatory mechanisms to prevent telomere shortening in OSA. On the other hand, the existence of longer telomere in subjects with moderate and severe OSA may also indicate triggering of molecular mechanisms which may contribute to cancer development. Further studies are needed to explain the role of hypoxia in telomere dynamics in OSA, and the interactions between telomere length and increased longevity reported in older patients with OSA. Support or Funding Information NIH R01 grant (#HL65176); Singh P. is supported by AHA scientist development grant (11SDG7260046). Becari C. is supported by grant from CNPq‐Brazil (# 203802/2014‐4).

Introduction: Renin-Angiotensin System (RAS) regulates the cardiovascular system and has been implicated in the development of abdominal aortic aneurysm (AAA). RAS modulates function via balancing the ACE/Chymase/AngII-AT1 receptor and ACE-2/Ang(1-7)-Mas receptor axis. Preferential activation of the ACE/Chymase/AngII-AT1 receptor pathway of the RAS contributes to dysregulation of cardiovascular system and disease while the Ang(1-7)-MasR axis contributes to anti-inflammatory pathways. Therefore, identifying the RAS axis mechanism involved in growth, progression, or the risk of rupture in AAA humans could bring a novel treatment perspective. Hypothesis: We hypothesize that in the AAA, the local RAS is altered such as it favours the ACE/AngII/AT1R axis while decreasing the ACE-2/Ang(1-7)/MasR pathway, with consequent AAA development. Objective: We sought to investigate the expression of RAS components in the AAA human aorta. Methods: Aorta tissue from AAA patients (n=21) was collected during the AAA conventional repair surgery, and aorta control aortas were obtained from organ donors (Control, n=11). Protein expression of renin, chymase, ACE, ACE-2 AT1, AT2, and MAS receptors was analyzed by Western Blotting. Results: Our AAA cohort consisted mostly males (76.6% AAA vs. 63.6% Control, p=0.68), smokers or ex-smokers (90.4% AAA vs. 36.3% Control, p=0.002) and most of them had hypertension(71.4% AAA vs. 36.3% Control, p=0.07). Analysis of protein expression in the AAA group showed that ACE and AT1 receptors were upregulated compared with Control (p=0.05; p=0.02, respectively,), while chymase expression was decreased in AAA compared to the control (p=0.03). Additionally, the AAA group showed downregulation in ACE-2 and AT2 compared with Control (respectively, p=0.01, p=0.03). There was no significant difference in the expression of renin and MAS receptors between groups (p=0.52, p=0.41, respectively,). Conclusions: Our data show that the ACE/AT1R axis was upregulated while ACE-2 and AT2 receptors were downregulated in the AAA aorta. Our results implicate local RAS in AAA development and warrant further studies.

Elastase-2 (ELA-2) enzyme generates angiotensin-II (AngII) in arteries and is implicated in abnormal vascular remodeling in animal models.Our group demonstrated previously that ELA-2 knockout (ELA-2KO) mice were less susceptible to develop an aorta dilation in a response to AngII infusion. In this study, we hypothesize that susceptibility to an aorta dilation and abdominal aortic aneurysm (AAA) is mediated by AngII receptors (AT1 and AT2). Methods: Male wild type (C57bl/6, WT) and ELA-2KO (CELA-2aTm1Bdr) mice were treated with either saline or AngII (2.28g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. Mice were divided into four groups: WT treated with saline (WT+SAL, n=5), ELA-2KO treated with saline (ELA-2KO+SAL, n=5), WT treated with AngII (WT+AngII,n=5), and ELA-2KO treated with AngII (ELA-2KO+AngII, n=5). Protein expression of AT1 and AT2 receptor, CD68, and α-actin was measured by immunofluorescence in formalin-fixed, paraffin-embedded aorta tissue. ANOVA and Kruskal Wallis tests were used to compare the average fluorescent intensity between groups. Results: AngII treatment was associated with increased AT1 receptor expression in a WT group, but not with AT2 receptor expression (vs. WT+SAL,p=0.06 and p=0.31, respectively). The ELA-2KO group showed no difference in AT1 receptor expression in a response to AngII infusion compared to a ELA-2KO+SAL group (p=0.81). While ELA-2KO+Ang II mice had lower AT2 expression compared to ELA-2KO+SAL (p=0.05). The α-actin expression was similar in all groups. WT+AngII group expressed more CD68 expression in a response to an AngII treatment that was increased in a WT group (p=0.03), but not in a ELA-2KO group. Conclusion: Our data demonstrate that Ang II treatment did not increase an expression of AT1 receptor in ELA-2KO, but was associated with a downregulation of AT2 receptors. Taken together, this suggests That ELA-2KO mice resistance to developing an aorta dilation/AAA is related to downregulation of Ang II receptors. Our results also highlight the importance of the local/tissue response in the pathophysiology of AAA.

Abstract Objective: The risk of premature deaths in patients with epilepsy (approx. 50 mln. patients worldwide) is about 2–3 times higher as compared to general population. This phenomenon is mainly explained by cardiovascular causes as well as sudden unexpected deaths in epilepsy (SUDEP). Epilepsy is associated with sympathetic overdrive and renin-angiotensin-system abnormalities all of which may be implicated in organ damage (both directly and indirectly via high blood pressure; BP). In our study, we aimed at the evaluation of several cardiovascular risk factors and organ damage in patients with epilepsy; its’ relation to disease control and comorbid hypertension. Design and method: A total of 48 patients and matched controls were included in the study. Anthropometry, biochemical assessment, office and ambulatory blood pressure, structural and/ or functional vascular changes were recorded. One-way ANOVA and ANCOVA were employed (mean ± SE). Results: Patients were comparable in terms of age and BMI. Hypertensives were aware of high BP in 50% of cases. Study subgroups were comparable in terms of heart rate, serum uric acid, triglicerides, HDL, glucose, serum creatinine and eGFR, serum potassium (P = NS for all comparisons). Total cholesterol was the lowest in well-controlled epileptic patients which was followed by refractory disease and epilepsy with comorbid hypertension (167.6 ± 6.7 vs. 196.9 ± 7.4 vs. 223.5 ± 8.9; respectively). Patients with refractory epilepsy had comparable serum LDL and PWV to hypertensive well-controlled epileptics; both contrasted with values recorded in patients with well-controlled epilepsy who were free of hypertension (LDL: 121.7 ± 6.8 vs. 140.9 ± 8.2 vs. 99.2 ± 6.1; respectively, and PWV: 6.4 ± 0.24 vs. 6.8 ± 0.30 vs. 5.5 ± 0.22; respectively). Reported differences were valid after adjustment for age and BMI. Conclusions: Except for BP values, patients with refractory epilepsy who are free of hypertension have similar CV risk profile to patients with high BP. These findings along with underdiagnosed hypertension may explain higher CV mortality and morbidity documented in epilepsy.

Objective: Elastase-2 (ELA-2), a chymotrypsyn-serine protease elastase family member 2A, is expressed in several tissues such as the lungs, heart, liver, kidneys, brain, and vessels. ELA-2 was found to generate angiotensin II (AngII) in arteries and contribute to resistance arteries and vascular remodeling in animal models. It has also been shown that continuous infusion of AngII induces abdominal aortic aneurysm (AAA) in mice. Therefore, we sought to investigate the role of ELA-2 in an aortic dilation, which is a risk factor to AAA development, in a mouse model. Design and method: Male wild type (C57bl/6, WT) and ELA-2 knockout (CELA-2aTm1Bdr; ELA-2 KO) mice were treated with saline or angiotensin II (AngII, 2.28 g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. To evaluate the role of elastase-2 in a AAA development, mice were divided into four groups: WT treated with saline (WT+SAL), ELA-2KO treated with saline (ELA-2KO+SAL), WT treated with AngII (WT+AngII), and ELA-2KO treated with Ang II (ELA-2KO+AngII). The vascular ultrasound (US) was done before treatment and once a week during 28 days of treatment. The abdominal aorta measurements such as maximum aortic diameter, aortic para-renal diameter, aortic infra-renal diameter, and aortic supra-renal diameter were collected. A dilated aorta is a risk factor aortic rupture/aneurysm. Statistical analyses were performed by the Shapiro Wilk Normality test, two-way ANOVA with Sidak's multiple comparisons test. This study is approved by the Ethics Committee (CEUA-131/2019). Results: The most dilated aorta as measured by the maximum aorta diameter was detected in WT+AngII group and was 60% higher than in the WT+Saline (p = 0.01). There was no significant difference in the maximum aorta diameter between ELA-KO+SAL vs. ELA-2KO+AngII (p = 0.8). The measurement of dilation in aortic para-renal and aortic infra-renal showed that AngII induced a dilation in WT+AngII (p < 0.05), while not modified these parameters in ELA-2KO+AngII group. The aortic supra-renal diameter parameters and weight showed no differences between groups. Conclusions: These results suggest that ELA-2KO mice might be less susceptible to develop an aorta dilation. Therefore, Elastase-2 is a candidate factor that contributes to the formation and/or development of abdominal aortic aneurysm.

Telomere length (TL) is associated with cardiovascular disease (CVD) and cancer. Obstructive sleep apnea (OSA) is also linked to higher risk of CVD and cancer, and to TL. We investigated the association between TL and risk of major adverse cardiac events (MACE) and cancer in OSA patients. We studied 210 individuals undergoing sleep-related studies between 2000 and 2007. Baseline characteristics and follow-up data (available in 164 subjects) were obtained from clinic records. Incidence rates were calculated for the entire group and by OSA status. Hazard ratios were calculated to estimate effects of OSA and TL on risk of MACE and cancer. In total, 32 individuals (20%) developed MACE and/or cancer during 12.7-year follow-up. The OSA group had a higher likelihood of cancer (16.0 vs. 4.9 events per 1000 person-years, P = 0.044) but no clear evidence of an elevated incidence of MACE (10.8 vs. 4.8 events per 1000 person-years, P = 0.293) compared to the non-OSA group. There was no association between TL and MACE- (HR = 1.01, 95% CI 0.78–1.28), or cancer-risk (HR = 1.18, 95% CI 0.96–1.43). Our study warrants further investigation of any modulating effect of OSA on TL and the risk of MACE and cancer.