Chronic Elevation Research Articles

MK-8719, a Novel and Selective O-GlcNAcase Inhibitor That Reduces the Formation of Pathological Tau and Ameliorates Neurodegeneration in a Mouse Model of Tauopathy.

Deposition of hyperphosphorylated and aggregated tau protein in the central nervous system is characteristic of Alzheimer disease and other tauopathies. Tau is subject to O-linked N-acetylglucosamine (O-GlcNAc) modification, and O-GlcNAcylation of tau has been shown to influence tau phosphorylation and aggregation. Inhibition of O-GlcNAcase (OGA), the enzyme that removes O-GlcNAc moieties, is a novel strategy to attenuate the formation of pathologic tau. Here we described the in vitro and in vivo pharmacological properties of a novel and selective OGA inhibitor, MK-8719. In vitro, this compound is a potent inhibitor of the human OGA enzyme with comparable activity against the corresponding enzymes from mouse, rat, and dog. In vivo, oral administration of MK-8719 elevates brain and peripheral blood mononuclear cell O-GlcNAc levels in a dose-dependent manner. In addition, positron emission tomography imaging studies demonstrate robust target engagement of MK-8719 in the brains of rats and rTg4510 mice. In the rTg4510 mouse model of human tauopathy, MK-8719 significantly increases brain O-GlcNAc levels and reduces pathologic tau. The reduction in tau pathology in rTg4510 mice is accompanied by attenuation of brain atrophy, including reduction of forebrain volume loss as revealed by volumetric magnetic resonance imaging analysis. These findings suggest that OGA inhibition may reduce tau pathology in tauopathies. However, since hundreds of O-GlcNAcylated proteins may be influenced by OGA inhibition, it will be critical to understand the physiologic and toxicological consequences of chronic O-GlcNAc elevation in vivo. SIGNIFICANCE STATEMENT: MK-8719 is a novel, selective, and potent O-linked N-acetylglucosamine (O-GlcNAc)-ase (OGA) inhibitor that inhibits OGA enzyme activity across multiple species with comparable in vitro potency. In vivo, MK-8719 elevates brain O-GlcNAc levels, reduces pathological tau, and ameliorates brain atrophy in the rTg4510 mouse model of tauopathy. These findings indicate that OGA inhibition may be a promising therapeutic strategy for the treatment of Alzheimer disease and other tauopathies.

Chronic elevation of renal venous pressure induces extensive renal venous collateral formation and modulates renal function and cardiovascular stability in rats.

Acutely increased renal venous pressure (RVP) impairs renal function, but the long-term impact is unknown. We investigated whether chronic RVP elevation impairs baseline renal function and prevents exacerbation of renal dysfunction and cardiovascular instability upon further RVP increase. RVP elevation (20-25 mmHg) or sham operation (sham) was performed in rats. After 1 wk (n = 17) or 3 wk (n = 22), blood pressure, RVP, renal blood flow (RBF), renal vascular conductance (RVC), and glomerular filtration rate (GFR) were measured at baseline and during superimposed RVP increase. Chronic RVP elevation induced extensive renal venous collateral formation. RVP fell to 6 ± 1 mmHg at 1 wk and 3 ± 1 mmHg at 3 wk. Baseline blood pressure and heart rate were unaltered compared with sham. RBF, RVC, and GFR were reduced at 1 wk but normalized by 3 wk. Upon further RVP increase, the drop in mean arterial pressure was attenuated at 3 wk compared with 1 wk (P < 0.05), whereas heart rate fell comparably across all groups; the mean arterial pressure-heart rate relationship was disrupted at 1 and 3 wk. RBF fell to a similar degree as sham at 1 wk (-2.3 ± 0.7 vs. -3.9 ± 1.2 mL/min, P = 0.066); however, at 3 wk, this was attenuated compared with sham (-1.5 ± 0.5 vs. -4.2 ± 0.7 mL/min, P < 0.05). The drop in RVC and GFR was attenuated at 1 and 3 wk (P < 0.05). Thus, chronic RVP elevation induced by partial renal vein ligation elicits extensive renal venous collateral formation, and although baseline renal function is impaired, chronic RVP elevation in this manner induces protective adaptations in kidneys of healthy rats, which attenuates the hemodynamic response to further RVP increase.

Chronically Elevating Circulating Ketones Can Reduce Cardiac Inflammation and Blunt the Development of Heart Failure

Previous studies have shown beneficial effects of acute infusion of the primary ketone body, β-hydroxybutyrate, in heart failure (HF). However, whether chronic elevations in circulating ketones are beneficial remains unknown. To chronically elevate circulating ketones in mice, we deleted the expression of the ketolytic, rate-limiting-enzyme, SCOT (succinyl-CoA:3-ketoacid-CoA transferase 1; encoded by Oxct1), in skeletal muscle. Tamoxifen-inducible skeletal muscle-specific Oxct1Muscle-/- knockout (n=32) mice and littermate controls (wild type; WT; n=35) were subjected to transverse aortic constriction (TAC) surgery to induce HF. Deletion of SCOT in skeletal, but not cardiac muscle resulted in elevated concentrations of fasted circulating β-hydroxybutyrate in knockout mice compared with WT mice (P=0.030). Five weeks following TAC, WT mice progressed to HF, whereas knockout mice with elevated fasting circulating ketones were largely protected from the TAC-induced effects observed in WT mice (ejection fraction, P=0.011; mitral E/A, P=0.012). Furthermore, knockout mice with TAC had attenuated expression of markers of sterile inflammation and macrophage infiltration, which were otherwise elevated in WT mice subjected to TAC. Lastly, addition of β-hydroxybutyrate to isolated hearts was associated with reduced NLRP3 (nucleotide-binding domain-like receptor protein 3)-inflammasome activation, which has been previously shown to play a role in contributing to HF-induced cardiac inflammation. These data show that chronic elevation of circulating ketones protects against the development of HF that is associated with the ability of β-hydroxybutyrate to directly reduce inflammation. These beneficial effects of ketones were associated with reduced cardiac NLRP3 inflammasome activation, suggesting that ketones may modulate cardiac inflammation via this mechanism.

1898-P: Colonic Short-Chain Fatty Acids Lower Endogenous Glucose Production

Hyperglycemia is a hallmark characteristic of diabetes, resulting in elevated blood glucose levels, due in part to a chronic elevation in endogenous hepatic glucose production (GP). Recent work has highlighted the gut microbiota as a salient contributor to energy and glucose homeostasis. One potential mechanism may be through increased short-chain fatty acid (SCFA) signaling mechanisms. SCFAs are bacterial breakdown products of nondigestible dietary fibers, occurring mainly in the colon, and have been shown to improve glucose homeostasis. Interestingly, recent work has highlighted that ingested nutrients can activate small intestinal nutrient-sensing mechanisms to lower hepatic glucose production via a neuronal gut-brain-liver axis mediated via gut peptide signaling. However, no one has directly tested whether colonic SCFAs can regulate GP via a similar colonic neuronal mechanism. To test this, we directly infused SCFAs (acetate, propionate, butyrate; 10mM or 100mM) into the colon during a pancreatic euglycemic clamp, the gold standard for measuring endogenous glucose production and uptake, in high-fat diet (HFD) fed rats that we previously found to have diminished levels of SCFAs in the large intestine. Administration of either acetate, propionate or butyrate (10mM or 100mM) directly into the colon of HFD-fed rats resulted in an increased glucose infusion rate needed to maintain euglycemia, which was due to a significant decrease in endogenous GP compared to saline infusion. Furthermore, we found that this was mediated via GLP-1 receptor signaling, as co-administration of exendin-9 with either SCFA (10mM) abolished the GP-lowering effect. Additionally, portal levels of GLP-1 were significantly increased at the end of the pancreatic clamp in rats receiving infusion of acetate, butyrate, or propionate compared to saline. Taken together, this work demonstrates that colonic SCFAs can activate a GLP-1 receptor mediated pathway in the colon to lower endogenous GP. Disclosure A.I.L. Lane: None. S.N. Weninger: None. F. Duca: None. Funding National Institutes of Health (R01DK121804)

Chronic elevation of plasma cortisol causes differential expression of predominating glucocorticoid in plasma, saliva, fecal, and wool matrices in sheep

There is increasing interest in using nonblood measures of glucocorticoids to assess the physiological response to chronic stress conditions. In sheep, cortisol has been measured in various matrices including saliva, feces, and wool, but comprehensive studies of the relationship between plasma concentrations of cortisol and concentrations in these nonblood matrices are lacking. Therefore, we tested the hypothesis that administration of cortisol to sheep would result in elevated concentrations of cortisol in blood, saliva, feces, and wool. Merino ewes were administered with saline or 2 mg/kg BW/d hydrocortisone acetate (HCA) by intramuscular (i.m.) injection for 28 d. This treatment was imposed to mimic circulating cortisol concentrations experienced during periods of chronic stress. Cortisol and cortisone were directly measured in plasma, saliva, and wool before, during, and after treatment with saline or HCA. A 14-d pre-treatment and a 14-d post-treatment period were used to measure time taken for glucocorticoid concentrations in each of the matrices to return to baseline levels. Cortisol was also measured in feces before, during, and after treatment. Wool growth was also measured. Before treatment, there was no difference in the concentration of cortisol or cortisone in plasma, saliva, feces, or wool in animals treated with saline or HCA. In contrast, treatment with HCA increased (P < 0.05) concentrations of both cortisol and cortisone in plasma, saliva, and wool and of cortisol in feces. In plasma, cortisol concentrations were higher than cortisone (P < 0.05), whereas saliva cortisol and cortisone concentrations did not differ significantly. In wool, the concentration of cortisone was about 19-fold higher than that of cortisol during treatment and post-treatment periods. Treatment with HCA inhibited wool growth. These results demonstrate that an increase in glucocorticoids in the blood of sheep is reflected in increases in saliva (after 7 d of treatment), feces (21 d), and wool (14 d). Therefore, measures of glucocorticoids in these matrices may provide a measure of activation of the adrenal glands over time in sheep, thereby providing a retrospective indicator of chronic stress. With respect to wool, it appears that cortisol is predominantly metabolized to cortisone in the skin or wool follicle and is stored as cortisone. Therefore wool cortisone may also provide an important measure in quantifiying chronic stress in sheep.

Antihypertensive power of Naringenin is mediated via attenuation of mineralocorticoid receptor (MCR)/ angiotensin converting enzyme (ACE)/ kidney injury molecule (Kim-1) signaling pathway

Hypertension is a condition with chronic elevation of blood pressure and a common preventable risk factor for cardiovascular disease with attendant global morbidity and mortality. The present study investigated the novel antihypertensive and neuroprotective effect of Naringenin on L-NG-Nitro arginine methyl ester (L-NAME) induced hypertension together with possible molecular mechanism of action. Rats were divided into four groups. Rats in Group A were normotensive. The hypertensive group (Group B) received 40 mg/kg) of L-NAME alone while Groups C and D were concurrently administered Naringenin (50 mg/kg) or Lisinopril (10 mg/Kg) together with L-NAME orally for 3 weeks. Blood pressure parameters, markers of oxidative stress and renal damage were measured. The immunohistochemistry of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme were also determined. Results indicated significant increases in malondialdehyde, advanced oxidation protein products, protein carbonyl contents and decrease in serum nitric oxide bioavailability in hypertensive rats. Furthermore, there were significant increases in serum myeloperoxidase, urinary creatinine, albumin and blood urea nitrogen in hypertensive rats in comparison to hypertensive rats treated with either Naringenin or Lisinopril. Immunohistochemistry reveal significant expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme in hypertensive rats. However, co-treatment with either Naringenin or Lisinopril mitigated both renal and neuronal oxidative stress, normalized blood pressure and lowered the expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme. Collectively, Naringenin offered a novel antihypertensive and neuroprotective effect through down regulation of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme.

Interleukin-6, Tumor Necrosis Factor-α, and High-sensitivity C-reactive Protein in Diabetic Patients with Helicobacter pylori in Kosovo

Helicobacter pylori is a Gram-negative spiral-shaped bacterium that infects from 30% to 50% of the world’s population and it is one of the most important in dyspeptic syndrome causes of gastritis and peptic ulcer. H. pylori is one of the most common chronic bacterial infections especially in the development countries because the socioeconomic contribute to chronic disease. The infection induces an acute polymorphonuclear infiltration in the gastric mucosa. Infection with H. pylori has been epidemiologically linked to some extra digestive conditions, including ischemic heart disease, diabetes mellitus (DM), and others. The patients with DM are at risk for H. pylori infection, since they have coupled susceptibility of to a wide range of infections as a result of chronic elevation of blood glucose level and impairment of immune functions. Chronic inflammation is a risk factor for coronary heart disease, because inflammation, vascular injury and thrombosis are considered to cause atherosclerosis. The risk of cardiovascular events is associated with increased levels of the acute phase proteins, C-reactive protein (CRP), and pro-inflammatory cytokines. Interleukin 6 (IL-6), a major pro-inflammatory cytokine is produced in a variety of tissues, including activated leukocytes, adipocytes, and endothelial cells. CRP is the principal downstream mediator of the acute phase response and is primarily derived through IL-6-dependent hepatic biosynthesis. Tumor necrosis factor-α (TNF-α), as an important inflammatory factor, has been shown to play a central role in the pathogenesis of diabetes. CRP and IL-6 were determinant of risk for the development of type 2 DM in apparently healthy middle-aged women. Since the prevalence of infected persons with H. pylori in Kosovo is high, the aim of this study was the evaluation of cytokines (IL1, TNF-α) and CRP in diabetic type 2 patients with positive H. pylori.

MON-171 Characterization of the Adrenal Gland and Adrenal Rest Tissues in Congenital Adrenal Hyperplasia

Background: Adrenonodular hyperplasia and tumor formation are common long-term complications of congenital adrenal hyperplasia (CAH) driven by chronic ACTH elevation. Clinical studies indicate that the majority of males with classic CAH have testicular adrenal rest tumors (TART). Ovarian adrenal rest tumors (OART) are less commonly observed. Little is known about the pathophysiology of adrenal rest, however both adrenal cortex and Leydig cell markers have been described in TART, suggesting a pluripotent embryological cell origin. Objective: To characterize adrenals and adrenal rest tissues of patients with CAH in comparison with normal tissues. Materials and Methods: Using immunohistochemistry (IHC) and, real-time qRT-PCR we investigated CAH-affected adrenals (n=5), adrenal rest tissues (n=2; 1 testicular, 1 ovarian), controls [normal adrenal (n=2), testis (n=1), and ovary (n=1)]. Tissue sections prepared from paraffin embedded tissue blocks were immunostained with adrenal [melanocortin 2 receptor (MC2R), delta-like homolog 1 (DLK-1), steroidogenic factor 1 (SF-1), steroidogenic acute regulatory protein (StAR) and other cytochrome P450 genes], inflammatory [interleukin 2 receptor (IL-2R), B-lymphocyte antigen (CD20), cluster of differentiation 3 (CD3), tumor necrosis factor alpha (TNFα), interleukin 6 (IL6)], and gonadal markers [progesterone receptor (PR), androgen receptor (AR), insulin-like 3 (INSL3)]. RNA was isolated and gene expression studies were performed. High-throughput RNA sequencing technology was used to analyze the differential transcriptome profiles between the CAH adrenals, adrenal rest and normal tissues.Results:In contrast to the controls, CAH adrenals and adrenal rest tissues showed the following:(i) IHC studies revealed 95% of tissue positive for adrenal zona-reticularis; (ii) significant nodular lymphocytic infiltration with a predominance of B and T lymphocytes and overexpression of lymphocyte markers IL-2R, CD20, CD3, and inflammatory cytokines TNFα and IL6; (iii) increased expression of adrenocortical specific genes MC2R, DLK1. Conclusion: CAH-affected adrenals and adrenal rest tissue have similar predominance of zona reticularis and demonstrate lymphocytic infiltration. Active inflammation may play a role in the abnormal development of adrenal and adrenal rest tissue in CAH patients.

Traumatic stress history interacts with sex and chronic peripheral inflammation to alter mitochondrial function of synaptosomes

BackgroundRepeated exposures to chronic stress can lead to long lasting negative behavioral and metabolic outcomes. Here, we aim to determine the impact of chronic stress and chronic low-level inflammation on behavior and synaptosomal metabolism. MethodsMale (n = 31) and female (n = 32) C57Bl/6 mice underwent chronic repeated predation stress or daily handling for two rounds of 15 consecutive days of exposure during the adolescent and early adult timeframes. Subsequently, mice were exposed to repeated lipopolysaccharide (LPS; 7.5 × 105 EU/kg) or saline injections every third day for eight weeks. Exploratory and social behaviors were assessed in the open field and social interaction tests prior to examination of learning and memory with the Barnes Maze. Mitochondrial function and morphology were assessed in synaptosomes post-mortem using the Cell Mito Stress test and Seahorse XFe24 analyzer, TEM, and western analysis, respectively. In addition, expression of TNF-α, IL-1ß, and ROMO1 were examined in the hippocampus and prefrontal cortex with Taqman qPCR. Circulating pro- and anti-inflammatory cytokines in the periphery were assessed using the MSD V-plex Proinflammatory Panel 1 following the first and last LPS injection as well as at the time of tissue collection. Circulating ROMO1 was assessed in terminal samples via ELISA. ResultsExposure to repeated predatory stress increased time spent in the corners of the open field, suggestive of anxiety-like behavior, in both males and females. There were no significant group differences in the social interaction test and minimal effects were evident in the Barnes maze. A history of chronic stress interacted with chronic LPS in male mice to lead to a deficit in synaptosomal respiration. Female mice were more sensitive to both chronic stress and chronic LPS such that either a history of chronic stress or chronic LPS exposure was sufficient to disrupt synaptosomal respiration in females. Both stress and chronic LPS were sufficient to increase inflammation and reactive oxygen in males centrally and peripherally. Females had increased markers of peripheral inflammation following acute LPS but no evidence of peripheral or central increases in inflammatory factors or reactive oxygen following chronic exposures. ConclusionCollectively, these data suggest that while metrics of inflammation and reactive oxygen are disrupted in males following chronic stress and chronic LPS, only the combined condition is sufficient to alter synaptosomal respiration. Conversely, although evidence of chronic inflammation or chronic elevation in reactive oxygen is absent, females demonstrate profound shifts in synaptosomal mitochondrial function with either a history of chronic stress or a history of chronic inflammation. These data highlight that different mechanisms are likely in play between the sexes and that sex differences in neural outcomes may be precipitated by sex-specific effects of life experiences on mitochondrial function in the synapse.

Prognostic model of the adaptive changes from hypertensive cardiopathy: from mild diastolic dysfunction to depressed systolic function.

By definition, hypertensive cardiopathy is a series of complex and variable effects responsible for the chronic elevation of blood pressure in the heart. It stands out within a broad spectrum of cardiovascular diseases associated with hypertension. To evaluate the capacity to predict the development of adaptive changes to hypertensive cardiopathy within ten years following diagnosis of the condition, using a model based on prognostic factors. A prospective cohort study was conducted in hypertensive patients. The patients were followed at the specialized hypertension physicians office of the specialty policlinic attached to Carlos Manuel de Céspedes University Hospital, in the Bayamo Municipality, Granma Province, Cuba, from 1 January 2008 to 31 December 2018. Coxs proportional regression model showed a significant statistical relationship between most of the factors and the development of the adaptive changes in hypertensive cardiopathy within ten years of follow-up after the diagnosis of this condition. The lack of blood pressure control (Hazard ratio: 2.090; confidence interval 95%: 1.688 to 2.588; p: 0.000) followed by stage 2 of hypertension (hazard ratio: 1.987; confidence interval 95%: 1.584 to 2.491; p: 0.000) were the main factors. Internal validation of the model, discriminant capacity (C- statistic: 0.897) and calibration Hosmer-Lemeshow (χ2: 5.384; p: 0.716), was acceptable. We develop a model to predict the progression of hypertensive cardiopathy from grade I to grade IV with adequate discriminatory capacity. The model is based on prognostic factors, among which characteristic effects of arterial hypertension, diabetes mellitus, and chronic kidney disease stood out.

Hydrogen Sulfide and β-Synuclein Are Involved and Interlinked in the Aging Glaucomatous Retina.

Purpose Glaucoma, one of the leading causes of irreversible blindness worldwide, is a group of disorders characterized by progressive retinal ganglion cell (RGC) loss. Synucleins, a family of small proteins, have been of interest in studies of neurodegeneration and CNS. However, their roles and functions in glaucoma are still not completely understood and remain to be explored. Our previous studies showed that α-synuclein and H2S play a pivotal role in glaucoma. This study aims to (1) elucidate the potential roles and functions of synucleins in glaucoma throughout aging, (2) investigate the interaction between the synucleins and H2S, and better understand the mechanism of H2S in neuroprotection. Methods The chronic IOP elevation model was carried out in 12 animals at different ages (3 months and 14 months), and RGCs were quantified by Brn3a staining. Mass spectrometric-assisted proteomics analysis was employed to measure synuclein levels and H2S producing proteins in retina. Secondly, the acute IOP elevation model was carried out in 12 juvenile animals, with or without intravitreal injection of GYY4137 (a H2S donor). RGCs were quantified along with the abundancy of synucleins. Results RGCs and β-synuclein (SNCB) are significantly changed in old animals. Under chronic IOP elevation, there is a significant RGC loss in old animals, whereas no significant change in young animals; SNCB is significantly downregulated and 3MST is significantly upregulated in young animals due to IOP, while no significant changes in old ones are notable. Under acute IOP elevation (approx. 55 mmHg), a significant RGC loss is observed; exogenous H2S significantly reduced RGC loss and downregulated SNCB levels. Conclusion The present study indicates a strong link between ageing and SNCB regulation. In young animals SNCB is downregulated going along with less RGC loss. Furthermore, increasing endogenous H2S is effective to downregulate SNCB and is neuroprotective against acute IOP elevation.

Chronic 2-Fold Elevation of Endogenous GDNF Levels Is Safe and Enhances Motor and Dopaminergic Function in Aged Mice

Glial cell line-derived neurotrophic factor (GDNF) supports function and survival of dopamine neurons that degenerate in Parkinson’s disease (PD). Ectopic delivery of GDNF in clinical trials to treat PD is safe but lacks significant therapeutic effect. In pre-clinical models, ectopic GDNF is effective but causes adverse effects, including downregulation of tyrosine hydroxylase, only a transient boost in dopamine metabolism, aberrant neuronal sprouting, and hyperactivity. Hindering development of GDNF mimetic increased signaling via GDNF receptor RET by activating mutations results in cancer. Safe and effective mode of action must be defined first in animal models to develop successful GDNF-based therapies. Previously we showed that about a 2-fold increase in endogenous GDNF expression is safe and results in increased motor and dopaminergic function and protection in a PD model in young animals. Recently, similar results were reported using a novel Gdnf mRNA-targeting strategy. Next, it is important to establish the safety of a long-term increase in endogenous GDNF expression. We report behavioral, dopamine system, and cancer analysis of five cohorts of aged mice with a 2-fold increase in endogenous GDNF. We found a sustained increase in dopamine levels, improvement in motor learning, and no side effects or cancer. These results support the rationale for further development of endogenous GDNF-based treatments and GDNF mimetic.

Chronic stress-induced elevation of IL-1β in the saliva and submandibular glands of mice.

Psychological stress is involved in the development of various oral diseases. Alterations in the levels of cytokines in the saliva of patients with stress-related oral diseases have been reported. However, the inconsistencies in the results of these studies might be attributed to differences in the local and systemic factors in the oral cavities of the patients. We examined the effect of chronic stress on three major inflammatory cytokines Interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the saliva and salivary glands of chronically stressed mice. Six-week-old C57BL/6J mice were randomly divided into a control and a stress group. The mice in stress group were exposed to 4h of stress daily for 10days and subsequently saliva, as well as the submandibular glands, were collected from both groups. The expression levels of cytokines in the saliva were examined by enzyme-linked immunosorbent assay. The submandibular glands were subjected to histopathological and mRNA expression analyses. IL-1β was significantly elevated in saliva of the chronic stressed mice. Furthermore, the mRNA expression levels of both IL-1β and IL-6 were significantly elevated in the submandibular gland of chronic stressed mice. IL-1β may be a potential salivary biomarker in response to chronic stress in mice.

Angiotensin II activates mTORC1 pathway in the kidneys through a pressor‐independent mechanism.

BackgroundAngiotensin II (AngII) has been found in vitro to stimulate the mTORC1 pathway and we have observed that AngII treatment enhanced mTORC1 phosphorylation of the ribosomal protein S6 kinase (pS6/S6) in a dose related manner in the NRK cell line. However, the in vivo effects of chronic elevations of AngII upon kidney activity of mTORC1 or upon mTORC2 (pAKT/AKT) have not been determined.GoalTo determine the effects of chronic hypertensive elevations of AngII upon the kidney expression of mTORC1 and mTORC2 in Sprague‐Dawley (SD) rats. Since it would normally not be possible to separate the direct effects of AngII upon mTORC1 activation from the effects of arterial pressure, studies were carried out using a unique servo‐control system that enabled the renal perfusion pressure (RPP) to the left kidney to be maintained at normal levels while the contralateral right kidney was subjected to the elevated systemic pressure.MethodsMale SD rats (n = 15) were maintained on a 0.4% NaCl diet throughout the study. At 9 weeks of age, rats were instrumented with carotid and femoral arterial catheters for measuring blood pressure, a femoral venous catheter for AngII infusion and a balloon occluder cuff was placed around the abdominal aorta between the renal arteries. The carotid and the femoral mean arterial pressures were used as surrogates to the RPP of the right and left kidneys respectively. After 7 days of recovery, baseline blood pressure was measured for 3 days, then the n = 9 of rats were infused with AngII (50 ng/kg/min) for 7 days to induce hypertension. N = 6 of rats were infused with only saline (vehicle control) throughout the study. A computer‐driven servo‐control system was used to inflate the aortic cuff to maintain left RPP to baseline levels while right RPP was left uncontrolled. Following 7 days of Ang II infusion, kidneys were removed for molecular analysis.ResultsPrior to infusion of AngII, baseline RPP values to the right and left kidneys were similar (117.3±3.0 vs 112.2±3.4 mmHg). Following 7 days of AngII infusion, the right RPP was significantly higher than left RPP (162.4±9.0 vs 113.2±2.7 mmHg; p&lt;0.05). Average 24 hr mean arterial pressures (MAP) remained unchanged in saline infused rats throughout the study. Western blot analysis of renal cortical tissue at day 7 found pS6/S6 was higher in both pressure‐uncontrolled and pressure‐controlled kidneys of AngII infused rats (2.25±0.21 vs 2.00±0.23) compared to saline infused rat kidneys (1.42±0.21; p&lt;0.05). In contrast, pAKT/AKT was unchanged by either AngII or differences in RPP.ConclusionChronic elevations of circulating AngII activates mTORC1 pathway in the kidneys through a pressor‐independent mechanism but has little effect on activation of mTORC2.Support or Funding InformationP01 HL116264, RO1 HL137748

N‐Acetylcysteine Attenuates Aldosterone induced Vasoconstriction in Individuals with Type 2 Diabetes

IntroductionIndividuals with type 2 diabetes (T2D) have a high risk of developing cardiovascular disease. Chronic elevation of plasma aldosterone could contribute to endothelial dysfunction within this population by ROS dependent mechanisms. The antioxidant N‐acetylcysteine (NAC) is known for its free radical scavenging properties and NAC may potentiate the activity of nitric oxide (NO) directly by increasing NO‐bioavailability. A shift in the balance between vasoconstrictor and vasodilator responses to aldosterone could be involved in the detrimental actions of aldosterone, and NAC could revoke this effect. The purpose of this study was to investigate if infusion of NAC would improve the vascular response to infused aldosterone in individuals with T2D.MethodsIn 13 subjects with T2D and 14 control subjects (matched on age and activity level), we measured leg hemodynamics during 10 min of incremental doses of infused aldosterone (0.2 and 5 ng/min/L leg volume) into the femoral artery, with and without co‐infusion of NAC (125 mg/kg/hour for 20 min; 25 mg/kg/hour (maintenance dose)). Leg blood flow (LBF; ultrasound Doppler) and arterial blood pressure was measured, and femoral arterial and venous blood samples were collected. Data was analyzed with one‐way repeated measure ANOVA (within groups) and two‐way ANOVA (between groups).ResultsLBF and leg vascular conductance (LVC) decreased during infusion of aldosterone at the high dose (p&lt;0.05) in the individuals with T2D, whereas co‐infusion of NAC attenuated this response. In the control group, there was no change in LBF and LVC during aldosterone infusion independently of NAC infusion. In both groups, venous aldosterone levels increased during aldosterone infusion (p&lt;0.05), and there was no difference between groups in aldosterone concentrations at baseline or during infusions.ConclusionThese results indicate that T2D is associated with a vasoconstrictor response to physiological levels of infused aldosterone and an increase in NO‐bioavailability attenuates this effect.Support or Funding InformationSupported by the Independent Research Fund, Denmark and Region of Southern Denmark

Blood Pressure is Positively Associated with Glycosylated Hemoglobin but not the Hypoxic Ventilatory Response in Obstructive Sleep Apnea Patients

Study ObjectiveThe hypoxic ventilatory response (HVR) is considered an index of peripheral chemoreflex sensitivity. Previous work has suggested that an increase in the HVR is responsible for acute nocturnal blood pressure surges that ultimately lead to chronic elevations in blood pressure. Previous results have also indicated that glycosylation of hemoglobin (HbA1C) impairs nitric oxide (NO) relaxation of vascular smooth muscle leading to chronic elevations in blood pressure. Given these findings, we hypothesized that the HVR and HbA1C would be positively associated with blood pressure during sleep before and 3 weeks after treatment with mild intermittent hypoxia (MIH) in humans with obstructive sleep apnea (OSA).MethodsEight hypertensive participants with OSA were exposed to twelve 2‐minute episodes of hypoxia (PETO2 ≈ 50 mmHg) separated by 2‐minute normoxic intervals during wakefulness for 15 days over 3 weeks. PETCO2 was sustained at 2 mmHg above baseline during MIH administration. HbA1C was measured prior to completion of the protocol on Day 1 and 15. Moreover, blood pressure was measured over a period of 24 hours, before and after completion of the MIH protocol.ResultsOn Day 1, the HVR was negatively associated with HbA1C (−0.74, p &lt; 0.04) and systolic (SBP) (R = −0.73, p &lt; 0.05), diastolic (DBP) (R = −0.69, p &lt; 0.05) and mean arterial blood pressure (MAP) (R = −0.71, p &lt; 0.05) recorded during the sleep period of a 24 hour cycle. In contrast, HbA1C was positively associated with measures of SBP (R = 0.82, p &lt; 0.01), DBP (R = 0.81, p &lt; 0.01) and MAP (R = 0.86, p &lt; 0.01) during sleep. Following treatment with MIH, blood pressure during sleep decreased (Before vs. After MIH: SBP 131.9 ± 4.1 vs. 122.9 ± 3.1, DBP 77.8 ± 3.9 vs. 72.8 ± 3.9, MAP 95.8 ± 3.8 vs. 89.5 ± 3.4, P &lt; 0.02). The change (Δ) in SBP during sleep following MIH was correlated to the Δ HbA1C (R = 0.85, p ≤ 0.01). Moreover, the degree to which SBP dipped before vs. after MIH was also correlated to Δ HbA1C (R = 0.87, p ≤ 0.01). In contrast, Δ HVR was not correlated to the Δ in blood pressure parameters.ConclusionAlthough peripheral chemoreflex sensitivity may be responsible for acute surges in blood pressure, this factor does not appear to be a strong predictor of chronic changes in blood pressure. In contrast, modifications in local signaling molecules may ultimately have the greatest impact on chronic modifications in blood pressure. Indeed, our findings lend support to previous results which suggest that increases in blood pressure may be coupled to the impairment of nitric oxide in response to glycosylated hemoglobin. This relationship may exist in the presence of a blunted HVR.Support or Funding InformationDepartment of Veterans Affairs (I01CX000125 &amp; 15SRCS003 JHM, 1IK1RX002945 GSP), and NIH (R56HL142757 &amp; R01HL142757 JHM).

Myocardial Edema, Myocyte Injury, and Disease Severity in Fabry Disease.

Background Cardiovascular magnetic resonance can demonstrate myocardial processes in Fabry disease (FD), such as low native T1 (sphingolipid storage) and late gadolinium enhancement (LGE, scar). Recently, high T2 (edema) has been observed in the basal inferolateral wall along with troponin elevation. We hypothesized that edema and myocyte injury would be chronically associated and have electrical, mechanical, and disease associations in FD. Methods A prospective international multicenter study was conducted on 186 consecutive FD patients (45.2±1.1 years, 58% females). Additionally, 28 patients with hypertrophic cardiomyopathy, 30 with chronic myocardial infarction and 59 healthy volunteers were included. All study participants underwent comprehensive cardiovascular magnetic resonance with T1 and T2 mapping, cines, and LGE imaging. Results LGE in the basal inferolateral wall in FD had T2 elevation (FD 58.2±5.0 ms versus hypertrophic cardiomyopathy 55.6±4.3 ms, chronic myocardial infarction 53.7±3.4 ms and healthy volunteers 48.9±2.5 ms, P<0.001), but when LGE was present there was also global T2 elevation (53.1±2.9 versus 50.6±2.2 ms, P<0.001). Thirty-eight percent of FD patients had high troponin. The strongest predictor of increased troponin was high basal inferolateral wall T2 (odds ratio, 18.2 [95% CI, 3.7-90.9], P<0.0001). Both T2 and troponin elevations were chronic over 1 year. High basal inferolateral wall T2 was associated with baseline global longitudinal strain impairment (P=0.005) and electrocardiographic abnormalities (long PR, complete bundle branch block, left ventricular hypertrophy voltage criteria, long QTc, and T-wave inversion, all P<0.05) and predicted clinical worsening after 1 year (Fabry stabilization index >20%, P=0.034). Conclusions LGE in Fabry has chronic local T2 elevation that is strongly associated with chronic troponin elevation. In addition, there is slight global T2 elevation. Both are associated with ECG and mechanical changes and clinical worsening over 1 year.

Pheochromocytoma Multisystem Crisis and Masquerading Disseminated Histoplasmosis in a Neurofibromatosis Type 1 Patient With Bilateral Adrenal Tumors.

Pheochromocytomas are rare catecholamine-secreting neuroendocrine tumors that can occasionally progress to life-threatening disease, including a multisystem crisis. Patients with Neurofibromatosis type 1 (NF1) may develop pheochromocytomas, and the consequent chronic elevation of plasma catecholamine levels could further complicate various cardiovascular and pulmonary manifestations they may have. A 37-year-old African American female with NF1 presented with severe dyspnea, chills, myalgia, vomiting, and abdominal pain. Within several hours of hospital admission, she developed progressive agitation and died from circulatory collapse. An autopsy revealed disseminated histoplasmosis with necrotizing granulomatosis in her lungs, mediastinum, liver, and spleen, as well as bilateral pheochromocytomas with one tumor showing marked hemorrhage. Additionally, she had cardiac hypertrophy, myocarditis, pulmonary edema, apical bullae, features of pulmonary hypertension and interstitial fibrosis. Disseminated histoplasmosis caused by the fungal organism Histoplasma capsulatum is rarely described in immunocompetent individuals. This case is presented to illustrate that chronic hypercatecholaminemia caused by pheochromocytomas may potentially mask disseminated fungal infections which in turn could induce pheochromocytoma multisystem crisis in susceptible patients with neurofibromatosis.

C-Reactive Protein Causes Adult-Onset Obesity Through Chronic Inflammatory Mechanism

Obesity is characterized by low-grade chronic inflammation. As an acute-phase reactant to inflammation and infection, C-reactive protein (CRP) has been found to be the strongest factor associated with obesity. Here we show that chronic elevation of human CRP at baseline level causes the obesity. The obesity phenotype is confirmed by whole-body magnetic resonance imaging (MRI), in which the total fat mass is 6- to 9- fold higher in the CRP rats than the control rats. Univariate linear regression analysis showed different growth rates between the CRP rats and the control rats, and that the difference appears around 11 weeks old, indicating that they developed adult-onset obesity. We also found that chronic elevation of CRP can prime molecular changes broadly in the innate immune system, energy expenditure systems, thyroid hormones, apolipoproteins, and gut flora. Our data established a causal role of CRP elevation in the development of adult-onset obesity.

Effect of food limitation and reproductive activity on fecal glucocorticoid metabolite levels in banded mongooses

BackgroundGlucocorticoids mediate responses to perceived stressors, thereby restoring homeostasis. However, prolonged glucocorticoid elevation may cause homeostatic overload. Using extensive field investigations of banded mongoose (Mungos mungo) groups in northern Botswana, we assessed the influence of reproduction, predation risk, and food limitation on apparent homeostatic overload (n=13 groups, 1542 samples from 268 animals). We experimentally manipulated reproduction and regulated food supply in captive mongooses, and compared their glucocorticoid responses to those obtained from free-living groups.ResultsAt the population level, variation in glucocorticoid levels in free-living mongooses was explained by food limitation: fecal organic matter, recent rainfall, and access to concentrated anthropogenic food resources. Soil macrofauna density and reproductive events explained less and predation risk very little variation in glucocorticoid levels. Reproduction and its associated challenges alone (under regulated feeding conditions) increased glucocorticoid levels 19-fold in a captive group. Among free-living groups, glucocorticoid elevation was seasonal (occurring in late dry season or early wet season when natural food resources were less available), but the timing of peak glucocorticoid production was moderated by access to anthropogenic resources (groups with fewer anthropogenic food sources had peaks earlier in dry seasons). Peak months represented 12- and 16-fold increases in glucocorticoids relative to nadir months with some animals exhibiting 100-fold increases. Relative to the captive group nadir, some free-living groups exhibited 60-fold increases in peak glucocorticoid levels with some animals exhibiting up to 800-fold increases. Most of these animals exhibited 1- to 10-fold increases relative to the captive animal peak.ConclusionsBanded mongooses exhibit seasonal chronic glucocorticoid elevation, associated primarily with food limitation and secondarily with reproduction. Magnitude and duration of this elevation suggests that this may be maladaptive for some animals, with possible fitness consequences. In late dry season, this population may face a convergence of stressors (food limitation, agonistic encounters at concentrated food resources, evictions, estrus, mate competition, parturition, and predation pressure on pups), which may induce homeostatic overload.