Glucose-regulated phosphorylation of TET2 by AMPK reveals a pathway linking diabetes to cancer.

Diabetes is a complex metabolic syndrome that is characterized by prolonged high blood glucose levels and frequently associated with life-threatening complications1,2. Epidemiological studies have suggested that diabetes is also linked to an increased risk of cancer3-5. High glucose levels may be a prevailing factor that contributes to the link between diabetes and cancer, but little is known about the molecular basis of this link and how the high glucose state may drive genetic and/or epigenetic alterations that result in a cancer phenotype. Here we show that hyperglycaemic conditions have an adverse effect on the DNA 5-hydroxymethylome. We identify the tumour suppressor TET2 as a substrate of the AMP-activated kinase (AMPK), which phosphorylates TET2 at serine 99, thereby stabilizing the tumour suppressor. Increased glucose levels impede AMPK-mediated phosphorylation at serine 99, which results in the destabilization of TET2 followed by dysregulation of both 5-hydroxymethylcytosine (5hmC) and the tumour suppressive function of TET2 in vitro and in vivo. Treatment with the anti-diabetic drug metformin protects AMPK-mediated phosphorylation of serine 99, thereby increasing TET2 stability and 5hmC levels. These findings define a novel 'phospho-switch' that regulates TET2 stability and a regulatory pathway that links glucose and AMPK to TET2 and 5hmC, which connects diabetes to cancer. Our data also unravel an epigenetic pathway by which metformin mediates tumour suppression. Thus, this study presents a new model for how a pernicious environment can directly reprogram the epigenome towards an oncogenic state, offering a potential strategy for cancer prevention and treatment.

Randomized Placebo-Controlled Trial to Evaluate Effects of Eplerenone on Myocardial Perfusion and Function Among Persons With Human Immunodeficiency Virus (HIV)-Results From the MIRACLE HIV Study.

BACKGROUND: Increased renin angiotensin aldosterone system (RAAS) activity may contribute to excess cardiovascular disease in people with HIV (PWH). We investigated how RAAS blockade may improve myocardial perfusion, injury, and function among well-treated PWH. METHODS: Forty PWH, on stable ART, without known heart disease were randomized to eplerenone 50 mg PO BID (n = 20) or identical placebo (n = 20) for 12 months. The primary endpoints were (1) myocardial perfusion assessed by coronary flow reserve (CFR) on cardiac PET or stress myocardial blood flow (sMBF) on cardiac MRI or (2) myocardial inflammation by extracellular mass index (ECMi) on cardiac MRI. RESULTS: Beneficial effects on myocardial perfusion were seen for sMBF by cardiac MRI (mean [SD]: 0.09 [0.56] vs -0.53 [0.68] mL/min/g; P = .03) but not CFR by cardiac PET (0.01 [0.64] vs -0.07 [0.48]; P = .72, eplerenone vs placebo). Eplerenone improved parameters of myocardial function on cardiac MRI including left ventricular end diastolic volume (-13 [28] vs 10 [26] mL; P = .03) and global circumferential strain (GCS; median [interquartile range 25th-75th]: -1.3% [-2.9%-1.0%] vs 2.3% [-0.4%-4.1%]; P = .03), eplerenone versus placebo respectively. On cardiac MRI, improvement in sMBF related to improvement in global circumferential strain (ρ = -0.65, P = .057) among those treated with eplerenone. Selecting for those with impaired myocardial perfusion (CFR <2.5 and/or sMBF <1.8), there was a treatment effect of eplerenone versus placebo to improve CFR (0.28 [0.27] vs -0.05 [0.36]; P = .04). Eplerenone prevented a small increase in troponin (0.00 [-0.13-0.00] vs 0.00 [0.00-0.74] ng/L; P = .03) without effects on ECMi (0.9 [-2.3-4.3] vs -0.7 [-2.2--0.1] g/m2; P = .38). CD4+ T-cell count (127 [-38-286] vs -6 [-168-53] cells/µL; P = .02) increased in the eplerenone- versus placebo-treated groups. CONCLUSIONS: RAAS blockade with eplerenone benefitted key indices and prevented worsening of myocardial perfusion, injury, and function among PWH with subclinical cardiac disease when compared with placebo. CLINICAL TRIALS REGISTRATION: NCT02740179 (https://clinicaltrials.gov/ct2/show/NCT02740179?term=NCT02740179&draw=2&rank=1).

Effect of hypoglycemia on baroreflex sensitivity in individuals with type 2 diabetes: implications for autonomic control of cardiovascular function in diabetes.

PURPOSE: Hypoglycemia is associated with increased mortality, though the mechanisms underlying this association are not established. Hypoglycemia impairs the counterregulatory hormonal and autonomic responses to subsequent hypoglycemia. It is unknown whether hypoglycemia elicits a generalized impairment in autonomic control of cardiovascular function in individuals with type 2 diabetes. We tested the hypothesis that in individuals with type 2 diabetes, hypoglycemia impairs a key measure of cardiovascular autonomic homeostasis, baroreflex sensitivity. METHODS: Sixteen individuals with well-controlled type 2 diabetes and without known cardiovascular disease were exposed to two 90-min episodes of experimental hypoglycemia (2.8 mmol/L, 50 mg/dL) on the same day. All individuals experienced a hypoglycemic-hyperinsulinemic clamp in the morning (AM clamp) and again in the afternoon (PM clamp). Baroreflex sensitivity was assessed using the modified Oxford method before the initiation of each hypoglycemic-hyperinsulinemic clamp, during the last 30 min of hypoglycemia, and the following morning. A mixed effects model adjusting for sex, age, BMI, and insulin level, demonstrated a significant effect of hypoglycemia on baroreflex sensitivity. The study is registered at ClinicalTrials.gov (NCT03422471). RESULTS: Baroreflex sensitivity during PM hypoglycemia was reduced compared to baseline, during AM hypoglycemia, and the next day. Insulin levels positively correlated with baroreflex sensitivity at baseline and during AM hypoglycemia. CONCLUSION: Exposure to hypoglycemia impairs a key measure of autonomic control of cardiovascular function and, thus, may increase the risk of cardiac arrhythmias and blood pressure lability in individuals with type 2 diabetes. This effect is attenuated in part by increased insulin levels.

Effects of Mineralocorticoid Receptor Blockade and Statins on Kidney Injury Marker 1 (KIM-1) in Female Rats Receiving L-NAME and Angiotensin II.

Kidney injury molecule-1 (KIM-1) is a biomarker of renal injury and a predictor of cardiovascular disease. Aldosterone, via activation of the mineralocorticoid receptor, is linked to cardiac and renal injury. However, the impact of mineralocorticoid receptor activation and blockade on KIM-1 is uncertain. We investigated whether renal KIM-1 is increased in a cardiorenal injury model induced by L-NAME/ANG II, and whether mineralocorticoid receptor blockade prevents the increase in KIM-1. Since statin use is associated with lower aldosterone, we also investigated whether administering eiSther a lipophilic statin (simvastatin) or a hydrophilic statin (pravastatin) prevents the increase in renal KIM-1. Female Wistar rats (8-10 week old), consuming a high salt diet (1.6% Na+), were randomized to the following conditions for 14 days: control; L-NAME (0.2 mg/mL in drinking water)/ANG II (225 ug/kg/day on days 12-14); L-NAME/ANG II + eplerenone (100 mg/kg/day p.o.); L-NAME/ANG II + pravastatin (20 mg/kg/day p.o.); L-NAME/ANG II + simvastatin (20 mg/kg/day p.o.). Groups treated with L-NAME/ANG II had significantly higher blood pressure, plasma and urine aldosterone, cardiac injury/stroke composite score, and renal KIM-1 than the control group. Both eplerenone and simvastatin reduced 24-h urinary KIM-1 (p = 0.0046, p = 0.031, respectively) and renal KIM-1 immunostaining (p = 0.004, p = 0.037, respectively). Eplerenone also reduced renal KIM-1 mRNA expression (p = 0.012) and cardiac injury/stroke composite score (p = 0.04). Pravastatin did not affect these damage markers. The 24-h urinary KIM-1, renal KIM-1 immunostaining, and renal KIM-1 mRNA expression correlated with cardiac injury/stroke composite score (p < 0.0001, Spearman ranked correlation = 0.69, 0.66, 0.59, respectively). In conclusion, L-NAME/ANG II increases renal KIM-1 and both eplerenone and simvastatin blunt this increase in renal KIM-1.

Role of renin-angiotensin-aldosterone system activation and other metabolic variables in relation to arterial inflammation in HIV.

BACKGROUND: Arterial inflammation remains increased among persons with HIV (PWH) compared with persons without HIV (PWOH) even when controlling for traditional risk factors. We sought to understand whether increased renin-angiotensin-aldosterone system (RAAS) activation may be related to arterial inflammation in PWH and when compared with PWOH. DESIGN: Twenty PWH and 9 PWOH followed a controlled, standardized low and liberal sodium diet to simulate a RAAS-activated and RAAS-suppressed state, respectively. We measured serum lipoprotein-associated phospholipase A2 (LpPLA2) concentrations following both conditions to assess the physiologic dynamics of aldosterone in relation to arterial inflammation. RESULTS: LpPLA2 levels were significantly higher among PWH versus PWOH during both the RAAS-activated state[5.3(4.2, 6.1) versus 4.0(3.0, 4.8)nmol/L, median(interquartile range),p = .01]) and RAAS-suppressed state[4.4(3.9, 5.3) versus 3.8(3.4, 4.1)nmol/L,p = .01]. Among PWH, but not PWOH, LpPLA2 increased significantly with RAAS activation(p = .03). LpPLA2 levels measured during the RAAS-suppressed state among PWH remained relatively higher than LpPLA2 levels under both conditions among PWOH. Log LpPLA2 was related to log aldosterone during the RAAS-activated state(r = .39,p = .04) among all participants. Log LpPLA2 was correlated with visceral fat(r = .46,p = .04) and log systolic blood pressure(r = .57,p = .009) during a RAAS-activated state when an increase in aldosterone was stimulated in HIV. CONCLUSION: LpPLA2 is increased during a RAAS-activated state among PWH, but not among PWOH. Further, LpPLA2 was increased in both RAAS-activated and suppressed states in PWH compared with PWOH. These data suggest a biological link between increased aldosterone and arterial inflammation in this population. Future studies should test RAAS blockade on arterial inflammation as a targeted treatment approach in HIV.

Myeloid Mineralocorticoid Receptor Transcriptionally Regulates P-Selectin Glycoprotein Ligand-1 and Promotes Monocyte Trafficking and Atherosclerosis.

Objective: MR (mineralocorticoid receptor) activation associates with increased risk of cardiovascular ischemia while MR inhibition reduces cardiovascular-related mortality and plaque inflammation in mouse atherosclerosis. MR in myeloid cells (My-MR) promotes inflammatory cell infiltration into injured tissues and atherosclerotic plaque inflammation by unclear mechanisms. Here, we examined the role of My-MR in leukocyte trafficking and the impact of sex. Approach and Results: We confirm in vivo that My-MR deletion (My-MR-KO) in ApoE-KO mice decreased plaque size. Flow cytometry revealed fewer plaque macrophages with My-MR-KO. By intravital microscopy, My-MR-KO significantly attenuated monocyte slow-rolling and adhesion to mesenteric vessels and decreased peritoneal infiltration of myeloid cells in response to inflammatory stimuli in male but not female mice. My-MR-KO mice had significantly less PSGL1 (P-selectin glycoprotein ligand 1) mRNA in peritoneal macrophages and surface PSGL1 protein on circulating monocytes in males. In vitro, MR activation with aldosterone significantly increased PSGL1 mRNA only in monocytes from MR-intact males. Similarly, aldosterone induced, and MR antagonist spironolactone inhibited, PSGL1 expression in human U937 monocytes. Mechanistically, aldosterone stimulated MR binding to a predicted MR response element in intron-1 of the PSGL1 gene by ChIP-qPCR. Reporter assays demonstrated that this PSGL1 MR response element is necessary and sufficient for aldosterone-activated, MR-dependent transcriptional activity. Conclusions: These data identify PSGL1 as a My-MR target gene that drives leukocyte trafficking to enhance atherosclerotic plaque inflammation. These novel and sexually dimorphic findings provide insight into increased ischemia risk with MR activation, cardiovascular protection in women, and the role of MR in atherosclerosis and tissue inflammation.

Striatin genotype-based, mineralocorticoid receptor antagonist-driven clinical trial: study rationale and design.

OBJECTIVES: In human studies and genetically altered mouse studies, variants in the striatin gene (STRN) are associated with increased blood pressure (BP) and aldosterone on a liberal salt diet. This clinical trial is based on the presumed mechanism for striatin-associated HTN - increased aldosterone. It is designed to determine if participants with the STRN risk alleles will have a greater BP reduction on a liberal salt diet with a specific, mechanism-based therapy - a mineralocorticoid receptor antagonist, eplerenone - as compared with a nonspecific anti-hypertensive therapy - amlodipine. METHODS: One hundred five hypertensive adults with the STRN risk alleles (SNP rs2540923 carriers or rs888083 homozygotes) will be enrolled in a 12-week, double-blind, dose-escalation, clinical trial. After a minimum 2-week washout period and baseline assessment of BP on a liberal salt diet, participants will be randomized to either daily eplerenone or amlodipine. Participants will take daily at-home BP recordings as a safety check. After 4 and 8 weeks of drug therapy, BP will be measured by the study team and medication will be increased, if needed, to achieve a participant goal BP of <140/90 mmHg.Anticipated results We anticipate that STRN risk allele carriers will demonstrate a greater reduction in BP with eplerenone and will require a lower dose of eplerenone to reach goal BP as compared with amlodipine. CONCLUSION: This is a proof-of-concept clinical trial. Positive results support the feasibility of performing genetically-defined, mechanistically-driven trials in HTN. Clinically, it would suggest that genetic biomarkers can identify individuals highly responsive to specific treatment.

Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes.

The circadian system generates endogenous rhythms of approximately 24 h, the synchronisation of which are vital for healthy bodily function. The timing of many physiological processes, including glucose metabolism, are coordinated by the circadian system, and circadian disruptions that desynchronise or misalign these rhythms can result in adverse health outcomes. In this review, we cover the role of the circadian system and its disruption in glucose metabolism in healthy individuals and individuals with type 2 diabetes mellitus. We begin by defining circadian rhythms and circadian disruption and then we provide an overview of circadian regulation of glucose metabolism. We next discuss the impact of circadian disruptions on glucose control and type 2 diabetes. Given the concurrent high prevalence of type 2 diabetes and circadian disruption, understanding the mechanisms underlying the impact of circadian disruption on glucose metabolism may aid in improving glycaemic control.

A clinical trial to evaluate the effect of statin use on lowering aldosterone levels.

BACKGROUND: Statins are the first-line pharmaceutical agent in the management of hypercholesterolemia and cardiovascular (CV) risk reduction, and the most commonly prescribed class of drugs worldwide. Studies describing CV risk reduction independent of LDL-cholesterol lowering have evoked an interest in the pleiotropic mechanisms of statins' benefits. We recently demonstrated that administration of statins in animal models lowers aldosterone levels and observed an association between statin use and reduced aldosterone levels in two human cohorts, with lipophilic statins displaying a greater effect than hydrophilic statins. Therefore, we designed a randomized, placebo-controlled, double-blinded intervention study to assess whether statin treatment lowers aldosterone in a type-dependent manner in humans, with simvastatin (lipophilic) showing a greater effect than pravastatin (hydrophilic). METHODS/DESIGN: One hundred five healthy participants will be recruited from the general population to enroll in a 12-week, randomized, placebo-controlled, double-blinded, 3-arm clinical trial. Ninety participants are anticipated to complete the protocol. After baseline assessment of aldosterone levels, participants will be randomized to daily simvastatin, pravastatin, or placebo. Aldosterone levels will be assessed after 2 days on study drug and again after 6 weeks and 12 weeks on study drug. Prior to each aldosterone assessment, participants will consume an isocaloric sodium and potassium-controlled run-in diet for 5 days. Assessments will occur on an inpatient research unit to control for diurnal, fasting, and posture conditions. The primary outcome will compare 12-week angiotensin II-stimulated serum aldosterone by study drug. Secondary outcomes will compare baseline and 12-week 24-h urine aldosterone by study drug. DISCUSSION: Results from this rigorous study design should provide strong support that statins lower aldosterone levels in humans. These results may explain some of the beneficial effects of statins that are not attributed to the LDL-lowering effect of this important class of medications. Results would demonstrate that statin lipophilicity is an important attribute in lowering aldosterone levels. The outcomes of this program will have implications for the design of studies involving statin medications, as well as for the differential use of classes of statins. TRIAL REGISTRATION: ClinicalTrials.gov; NCT02871687 ; First Posted August 18, 2016.

Serum Lipocalin 2 (Neutrophil Gelatinase-Associated Lipocalin) in Relation to Biomarkers of Inflammation and Cardiac Stretch During Activation of the Renin-Angiotensin-Aldosterone System in Human Immunodeficiency Virus.

PURPOSE: To evaluate the relationship of lipocalin 2 to inflammation and cardiac injury with increased aldosterone in human immunodeficiency virus (HIV). METHODS: A standardized 6-day low-sodium diet was used to stimulate renin-angiotensin-aldosterone system (RAAS) activation, and serum lipocalin 2 and biomarkers of inflammation and cardiac stretch were assessed among persons with or without HIV. RESULTS: Lipocalin 2 levels increased with RAAS activation compared with suppression in the HIV group (median level [interquartile range], 71.3 [59.2-99.7] vs 67.0 [51.8-86.3] ng/mL; P = .01). During RAAS activation, lipocalin 2 was related to biomarkers of inflammation (tumor necrosis factor α [P = .007]), monocyte/macrophage activation (soluble CD163 [P = .005] and chemokine [C-C motif] ligand 2 [P = .03]), and markers of cardiac stretch (brain natriuretic peptide [P < .001] and N-terminal fragment of the prohormone brain natriuretic peptide [P = .001]) in HIV. CONCLUSION: Lipocalin 2 may be important in modulating aldosterone-induced inflammation, monocyte activation, and cardiac stretch during RAAS activation in HIV. CLINICAL TRIAL REGISTRATION: NCT01407237.

Oxytocin response to controlled dietary sodium and angiotensin II among healthy individuals.

Oxytocin, while classically known for its role in parturition, lactation, and social behavior, also has been implicated in the control of sodium homeostasis in animal models. To improve our understanding of oxytocin physiology in humans, we measured basal oxytocin levels under low- and liberal-dietary-sodium conditions and following a peripheral angiotensin II (ANG II) infusion. Ten healthy individuals underwent a 6-day standardized low-sodium diet and a 6-day liberal-sodium diet. Each diet was followed by a graded ANG II infusion for 30-min sequential intervals at doses of 0.3, 1.0, and 3.0 ng·kg-1·min-1. Fasting serum oxytocin was assessed before and after ANG II infusion. Basal oxytocin levels (1,498.5 ± 94.7 vs. 1,663.3 ± 213.9 pg/ml, P = 0.51) did not differ after the low- and liberal-sodium diets. Following the ANG II infusion, ANG II levels and mean arterial pressure significantly increased as expected. In contrast, the ANG II infusion significantly lowered oxytocin levels from 1,498.5 ± 94.7 vs. 1,151.7 ± 118.1 pg/ml ( P < 0.001) on the low-sodium diet and from 1,663.3 ± 213.9 vs. 1,095.2 ± 87.4 pg/ml ( P = 0.03) on the liberal-sodium diet. The percent change in oxytocin following the ANG II infusion did not differ by sodium diet (-25 ± 5% vs. -28 ± 7% low- vs. liberal-sodium conditions, P > 0.99). Dietary sodium intake did not affect circulating oxytocin levels among healthy individuals. Systemic oxytocin levels were significantly suppressed following a peripheral ANG II infusion independent of dietary sodium conditions.

"Nonfunctional" Adrenal Tumors and the Risk for Incident Diabetes and Cardiovascular Outcomes: A Cohort Study.

BACKGROUND: Benign adrenal tumors are commonly discovered on abdominal imaging. Most are classified as nonfunctional and are considered to pose no health risk, but some are considered functional because they secrete hormones that increase risk for metabolic and cardiovascular diseases. OBJECTIVE: To evaluate the hypothesis that nonfunctional adrenal tumors (NFATs) increase risk for cardiometabolic outcomes compared with absence of adrenal tumors. DESIGN: Cohort study. SETTING: Integrated hospital system. PARTICIPANTS: Participants with benign NFATs ("exposed"; n = 166) and those with no adrenal tumor ("unexposed"; n = 740), with at least 3 years of follow-up. MEASUREMENTS: Medical records were reviewed from the time of abdominal imaging for development of incident outcomes (hypertension, composite diabetes [prediabetes or type 2 diabetes], hyperlipidemia, cardiovascular events, and chronic kidney disease) (mean, 7.7 years). Primary analyses evaluated independent associations between exposure status and incident outcomes by using adjusted generalized linear models. Secondary analyses evaluated relationships between NFATs and cortisol physiology. RESULTS: Participants with NFATs had significantly higher risk for incident composite diabetes than those without adrenal tumors (30 of 110 [27.3%] vs. 72 of 615 [11.7%] participants; absolute risk, 15.6% [95% CI, 6.9% to 24.3%]; adjusted risk ratio, 1.87 [CI, 1.17 to 2.98]). No significant associations between NFATs and other outcomes were observed. Higher "normal" postdexamethasone cortisol levels (≤50 nmol/L) were associated with larger NFAT size and higher prevalence of type 2 diabetes. LIMITATION: Potential bias in the selection of participants and ascertainment of outcomes. CONCLUSION: Participants with NFATs had a significantly higher risk for diabetes than those without adrenal tumors. These results should prompt a reassessment of whether the classification of benign adrenal tumors as "nonfunctional" adequately reflects the continuum of hormone secretion and metabolic risk they may harbor. PRIMARY FUNDING SOURCE: National Institutes of Health and Doris Duke Charitable Foundation.

Effects of Sodium Restriction on Activation of the Renin-Angiotensin-Aldosterone System and Immune Indices During HIV Infection.

BACKGROUND: Human immunodeficiency virus (HIV)-infected patients demonstrate increased activation of the renin-angiotensin-aldosterone system (RAAS). We evaluated changes in immune markers with physiological RAAS activation. METHODS: Immune activation markers were assessed serially in 18 HIV-infected and 7 non-HIV-infected subjects consuming an ad libitum diet followed by a standardized low-sodium diet. RESULTS: Levels of CCL-2 (P = .0004) and soluble CD163 (P = .0001) significantly increased with sodium restriction and RAAS activation, compared with levels in individuals with ad libitum sodium intake, among chronically treated HIV-infected subjects (mean duration of ART [±SEM], 11 ± 1 years), but not among non-HIV-infected subjects of similar age and sex. CONCLUSIONS: Dietary sodium restriction, which activates RAAS, uniquely stimulates critical indices of immune activation during HIV infection. CLINICAL TRIALS REGISTRATION: NCT01407237.

Statin Use and Adrenal Aldosterone Production in Hypertensive and Diabetic Subjects.

BACKGROUND: Statins substantially reduce cardiovascular mortality and appear to have beneficial effects independent of their lipid-lowering properties. We evaluated the hypothesis that statin use may modulate the secretion of aldosterone, a well-known contributor to cardiovascular disease. METHODS AND RESULTS: We measured adrenal hormones in 2 intervention studies. In study 1 in hypertensive subjects, aldosterone was analyzed at baseline and after angiotensin II stimulation on both high- and low-sodium diets (1122 observations, 15% on statins for >3 months). Statin users had 33% lower aldosterone levels in adjusted models (P<0.001). Cortisol was not modified by statins. In secondary analyses, the lowest aldosterone levels were seen with lipophilic statins and with higher doses. Statin users had lower blood pressure and reduced salt sensitivity of blood pressure (both P<0.001). In study 2, aldosterone was measured in diabetic patients on a high-sodium diet, before and after angiotensin II stimulation (143 observations, 79% statin users). Again, statin users had 26% lower aldosterone levels (P=0.006), particularly those using lipophilic statins. Ex vivo studies in rat adrenal glomerulosa cells confirmed that lipophilic statins acutely inhibited aldosterone, but not corticosterone, in response to different secretagogues. CONCLUSIONS: Statin use among hypertensive and diabetic subjects was associated with lower aldosterone secretion in response to angiotensin II and a low-sodium diet in 2 human intervention studies. This effect appeared to be most pronounced with lipophilic statins and higher doses. Future studies to evaluate whether aldosterone inhibition may partially explain the robust cardioprotective effects of statins are warranted.

Thalamic mechanisms underlying alpha-delta sleep with implications for fibromyalgia.

Alpha-delta sleep is the abnormal intrusion of alpha activity (8- to 13-Hz oscillations) into the delta activity (1- to 4-Hz oscillations) that defines slow-wave sleep. Alpha-delta sleep is especially prevalent in fibromyalgia patients, and there is evidence suggesting that the irregularities in the sleep of these patients may cause the muscle and tissue pain that characterizes the disorder. We constructed a biophysically realistic mathematical model of alpha-delta sleep. Imaging studies in fibromyalgia patients suggesting altered levels of activity in the thalamus motivated a thalamic model as the source of alpha activity. Since sodium oxybate helps to alleviate the symptoms of fibromyalgia and reduces the amount of alpha-delta sleep in fibromyalgia patients, we examined how changes in the molecular targets of sodium oxybate affected alpha-delta activity in our circuit. Our model shows how alterations in GABAB currents and two thalamic currents, Ih (a hyperpolarization-activated current) and a potassium leak current, transform a circuit that normally produces delta oscillations into one that produces alpha-delta activity. Our findings suggest that drugs that reduce Ih conductances and/or increase potassium conductances, without necessarily increasing GABAB conductances, might be sufficient to restore delta sleep. Furthermore, they suggest that delta sleep might be restored by drugs that preferentially target these currents in the thalamus; such drugs might have fewer side effects than drugs that act systemically.

Cooperative Role of Mineralocorticoid Receptor and Caveolin-1 in Regulating the Vascular Response to Low Nitric Oxide-High Angiotensin II-Induced Cardiovascular Injury.

Aldosterone interacts with mineralocorticoid receptor (MR) to stimulate sodium reabsorption in renal tubules and may also affect the vasculature. Caveolin-1 (cav-1), an anchoring protein in plasmalemmal caveolae, binds steroid receptors and also endothelial nitric oxide synthase, thus limiting its translocation and activation. To test for potential MR/cav-1 interaction in the vasculature, we investigated if MR blockade in cav-1-replete or -deficient states would alter vascular function in a mouse model of low nitric oxide (NO)-high angiotensin II (AngII)-induced cardiovascular injury. Wild-type (WT) and cav-1 knockout mice (cav-1(-/-)) consuming a high salt diet (4% NaCl) received Nω-nitro-l-arginine methyl ester (L-NAME) (0.1-0.2 mg/ml in drinking water at days 1-11) plus AngII (0.7-2.8 mg/kg per day via an osmotic minipump at days 8-11) ± MR antagonist eplerenone (EPL) 100 mg/kg per day in food. In both genotypes, blood pressure increased with L-NAME + AngII. EPL minimally changed blood pressure, although its dose was sufficient to block MR and reverse cardiac expression of the injury markers cluster of differentiation 68 and plasminogen activator inhibitor-1 in L-NAME+AngII treated mice. In aortic rings, phenylephrine and KCl contraction was enhanced with EPL in L-NAME+AngII treated WT mice, but not cav-1(-/-) mice. AngII-induced contraction was not different, and angiotensin type 1 receptor expression was reduced in L-NAME + AngII treated WT and cav-1(-/-) mice. In WT mice, acetylcholine-induced relaxation was enhanced with L-NAME + AngII treatment and reversed with EPL. Acetylcholine relaxation in cav-1(-/-) mice was greater than in WT mice, not modified by L-NAME + AngII or EPL, and blocked by ex vivo L-NAME, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), or endothelium removal, suggesting the role of NO-cGMP. Cardiac endothelial NO synthase was increased in cav-1(-/-) versus WT mice, further increased with L-NAME + AngII, and not affected by EPL. Vascular relaxation to the NO donor sodium nitroprusside was increased with L-NAME + AngII in WT mice but not in cav-1(-/-) mice. Plasma aldosterone levels increased and cardiac MR expression decreased in L-NAME + AngII treated WT and cav-1(-/-) mice and did not change with EPL. Thus, during L-NAME + AngII induced hypertension, MR blockade increases contraction and alters vascular relaxation via NO-cGMP, and these changes are absent in cav-1 deficiency states. The data suggest a cooperative role of MR and cav-1 in regulating vascular contraction and NO-cGMP-mediated relaxation during low NO-high AngII-dependent cardiovascular injury.

Aldosterone and the Mineralocorticoid Receptor: Risk Factors for Cardiometabolic Disorders.

Preclinical studies have convincingly demonstrated a role for the mineralocorticoid receptor (MR) in adipose tissue physiology. These studies show that increased MR activation causes adipocyte dysfunction leading to decreased production of insulin-sensitizing products and increased production of inflammatory factors, creating an environment conducive to metabolic and cardiovascular disease. Accumulating data also suggest that MR activation may be an important link between obesity and metabolic syndrome. Moreover, MR activation may mediate the pathogenic consequences of metabolic syndrome. Recent attempts at reversing cardiometabolic damage in patients with type 2 diabetes using MR antagonists have shown promising results. MR antagonists are already used to treat heart failure where their use decreases mortality and morbidity over and above the use of traditional therapies alone. However, more data are needed to establish the benefits of MR antagonists in diabetes, obesity, and metabolic syndrome.

Dissociation of hyperglycemia from altered vascular contraction and relaxation mechanisms in caveolin-1 null mice.

Hyperglycemia and endothelial dysfunction are associated with hypertension, but the specific causality and genetic underpinning are unclear. Caveolin-1 (cav-1) is a plasmalemmal anchoring protein and modulator of vascular function and glucose homeostasis. Cav-1 gene variants are associated with reduced insulin sensitivity in hypertensive individuals, and cav-1(-/-) mice show endothelial dysfunction, hyperglycemia, and increased blood pressure (BP). On the other hand, insulin-sensitizing therapy with metformin may inadequately control hyperglycemia while affecting the vascular outcome in certain patients with diabetes. To test whether the pressor and vascular changes in cav-1 deficiency states are related to hyperglycemia and to assess the vascular mechanisms of metformin under these conditions, wild-type (WT) and cav-1(-/-) mice were treated with either placebo or metformin (400 mg/kg daily for 21 days). BP and fasting blood glucose were in cav-1(-/-) > WT and did not change with metformin. Phenylephrine (Phe)- and KCl-induced aortic contraction was in cav-1(-/-) < WT; endothelium removal, the nitric-oxide synthase (NOS) blocker L-NAME (N(ω)-nitro-L-arginine methyl ester), or soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced Phe contraction, and metformin blunted this effect. Acetylcholine-induced relaxation was in cav-1(-/-) > WT, abolished by endothelium removal, L-NAME or ODQ, and reduced with metformin. Nitric oxide donor sodium nitroprusside was more potent in inducing relaxation in cav-1(-/-) than in WT, and metformin reversed this effect. Aortic eNOS, AMPK, and sGC were in cav-1(-/-) > WT, and metformin decreased total and phosphorylated eNOS and AMPK in cav-1(-/-). Thus, metformin inhibits both vascular contraction and NO-cGMP-dependent relaxation but does not affect BP or blood glucose in cav-1(-/-) mice, suggesting dissociation of hyperglycemia from altered vascular function in cav-1-deficiency states.

Elevated Blood Pressure and Aldosterone Dysregulation in Young Black Women Versus White Women on Controlled Sodium Diets.

CONTEXT: Black women have a higher prevalence of hypertension as compared to White women. Differences in dietary sodium intake have been implicated as a contributing factor for the disparities in hypertension. OBJECTIVE: Our objective was to understand whether young Black women would have higher systolic blood pressure (SBP) than White women even on controlled sodium diets and to determine whether SBP differences were due to differences in dietary sodium intake and/or aldosterone regulation. DESIGN: The analyses included 525 hypertensive and normotensive women (ages 18-71) from the International Hypertensive Pathotype consortium, who were maintained on liberal sodium (LIB; >200 mEq sodium/day) and restricted sodium (RES; 10 mEq sodium/day) diets. RESULTS: Multivariate regression analyses (adjusted for age, race, study site, body mass index) found that Black women (ages 18-50) had significantly higher SBP than White women on both sodium diets: +8.7 ± 2.7 mmHg (P-value = .002) on a LIB diet and +8.5 ± 2.5 mmHg (P-value = .001) on a RES diet. Even among 18- to 35-year-olds-who were normotensive and nonobese-Black women had higher SBP: +7.9 ± 2.4 mmHg (P-value = .001) on a LIB diet and +7.6 ± 2.7 mmHg (P-value = .005) on a RES diet. Younger Black women also had higher plasma aldosterone concentration to plasma renin activity ratio (ARR) on both LIB and RES diets as well as a higher sodium-modulated aldosterone suppression-stimulation index-an indicator of aldosterone dysregulation. In younger Black women-but not in White women-there was a significant association between SBP and ARR on both LIB and RES diets. CONCLUSION: Young Black women had increased SBP and ARR as compared to White women on LIB and RES diets, which offers insights into the possible mechanisms for the increased hypertension and cardiovascular disease risk in an at-risk and understudied population.

Striatin Gene Variants Are Associated With Salt Sensitivity of Blood Pressure by Mechanisms That Differ in Women and Men.

BACKGROUND: Salt sensitivity of blood pressure (SSBP) is a substantial risk factor for cardiovascular morbidity and mortality. Striatin (STRN) is critical for estrogen and aldosterone nongenomic signaling. However, the role of biological sex on the SSBP phenotype associated with STRN gene variants remains unexplored. METHOD: Data from 1306 subjects participating in the Hypertensive Pathotype (HyperPATH) Consortium were used to identify STRN gene single-nucleotide variants associated with SSBP. Haploblock analysis revealed a novel diplotype in the upstream regulatory region of STRN (rs888083 and rs6744560), with 31% of subjects being homozygous for the risk diplotype. RESULTS: Individuals homozygous for the risk diplotype had significantly greater SSBP than nonrisk diplotypes (P<0.009). While a significant genotype/SSBP association was present in both sexes, their potential mechanisms differed. Women, but not men homozygous risk diplotypes, had significantly greater aldosterone levels than nonrisk diplotypes (5.8±0.4 versus 3.2±0.7 ng/dl; P=0.01; liberal Na+ diet, adjusted). Men, but not women, homozygous risk diplotypes, had significantly reduced renal plasma flow response to Angiotensin II than nonrisk diplotypes (delta 95.2±5.2 versus 122.9±10.2 mL/min per 1.73 m2; P=0.01; liberal Na+ diet, adjusted). The single-nucleotide variants composing the risk diplotype were associated with lower STRN mRNA expression in human tissues (in silico). CONCLUSION: In women, the primary driver of SSBP is increased aldosterone, while in men, it is reduced renal plasma flow responses. Thus, despite a common hypertensive phenotype (SSBP) in both sexes, the specific treatment approaches might differ to increase therapeutic gain and mitigate adverse effects. These genetic- and sex-based observational results require confirmation in a prospective clinical study.