TRα inhibits arterial renin-angiotensin system expression and prevents cholesterol accumulation in vascular smooth muscle cells.

OBJECTIVES: The tissue renin-angiotensin system (tRAS) plays a key role in the maintenance of cellular homeostasis but is also implicated in atherosclerosis. Thyroid hormone (TH) contributes, via genomic effects, to control of tRAS gene expression in the arterial wall and vascular smooth muscle cells (VSMCs). We investigated the specific functions of TH receptors-α and -ß (TRα and TRß) on tRAS gene expression in the aorta and VSMCs, and the potential protective effect of TRα against atherosclerosis. MATERIAL AND METHODS: Using aorta and cultured aortic VSMCs from TRα and TRß deficient mice, tRAS gene expression was analyzed by determining mRNA levels on real-time PCR. Gene regulation under cholesterol loading mimicking atherosclerosis conditions was also examined in VSMCs in vitro. RESULTS: TRα deletion significantly increased expression of angiotensinogen (AGT) and angiotensin II receptor type 1 subtype a (AT1Ra) at transcriptional level in aorta, a tissue with high TRα expression level. TRα activity thus seems to be required for maintenance of physiological levels of AGTand AT1Raexpression in the arterial wall. In addition, during cholesterol loading, TRα deletion significantly increased cholesterol content in VSMCs, with a weaker decrease in AGTexpression. CONCLUSION: TRα seems to have an inhibitory impact on AGTand AT1Raexpression, and loss of TRα function in TRα0/0 mice increases tRAS expression in the aortic wall. More importantly, TRα deletion significantly increases VSMC cholesterol content. Our results are consistent with a protective role of TRα against atherosclerosis.

Thyroid Hormone Receptor Alpha Deletion in ApoE-/- Mice Alters the Arterial Renin-Angiotensin System and Vascular Smooth Muscular Cell Cholesterol Metabolism.

Thyroid hormone (TH) regulates gene transcription by binding to TH receptors (TRs). TRs regulate the genes of lipid metabolism and the renin-angiotensin system (RAS). We examined the effect of TRα deletion in ApoE-/- mice (DKO mice) on the following: (i) the expression of genes controlling cholesterol metabolism and tissue (t)RAS in the liver and aorta and (ii) the expression of these genes and the regulation of cholesterol content in cultured vascular smooth muscle cells (VSMCs). TRα deletion in ApoE-/- mice led to the repression of genes involved in the synthesis and influx of cholesterol in the liver. However, TRα deletion in the arterial wall suppressed the expression of genes involved in the esterification and excretion of cholesterol and enhanced the expression of angiotensinogen (AGT). The VSMCs of the ApoE-/- and DKO mice increased their cholesterol content during cholesterol loading, but failed to increase the expression of ATP-binding cassette transporter A1 (ABCA1). T3 addition partially corrected these abnormalities in the cells of the ApoE-/- mice but not those of the DKO mice. In conclusion, TRα deletion in ApoE-/- mice slightly increases the expression of tRAS in the aorta and aggravates the dysregulation of cholesterol content in the VSMCs.

Changes in Brain Monoamines Underlie Behavioural Disruptions after Zebrafish Diet Exposure to Polycyclic Aromatic Hydrocarbons Environmental Mixtures.

Zebrafish were exposed through diet to two environmentally relevant polycyclic aromatic hydrocarbons (PAHs) mixtures of contrasted compositions, one of pyrolytic (PY) origin and one from light crude oil (LO). Monoamine concentrations were quantified in the brains of the fish after six month of exposure. A significant decrease in noradrenaline (NA) was observed in fish exposed to both mixtures, while a decrease in serotonin (5HT) and dopamine (DA) was observed only in LO-exposed fish. A decrease in metabolites of 5HT and DA was observed in fish exposed to both mixtures. Several behavioural disruptions were observed that depended on mixtures, and parallels were made with changes in monoamine concentrations. Indeed, we observed an increase in anxiety in fish exposed to both mixtures, which could be related to the decrease in 5HT and/or NA, while disruptions of daily activity rhythms were observed in LO fish, which could be related to the decrease in DA. Taken together, these results showed that (i) chronic exposures to PAHs mixtures disrupted brain monoamine contents, which could underlie behavioural disruptions, and that (ii) the biological responses depended on mixture compositions.

[Inflammation in the perivascular adipose tissue and atherosclerosis]. / Inflammation dans le tissu adipeux péri-artériel et athérome.

In atherosclerosis studies, there are few data, especially in men, on the biology of perivascular adipose tissue (PVAT) compared to that of other adipose tissue (AT), on amendments in obesity, and its possible role in the development of atherosclerosis. We conducted an ex vivo human study on pericarotid adipose tissue-collected in the immediate vicinity (PVATp) and away from the plate (tapas)-and subcutaneous (SC) neck gathered during surgery from patients suffering from atheromatous carotid disease. In addition, we conducted a study in obese Zucker rats (models of obesity and insulin resistance) and Wistar rats subjected to moderate stress. In these models, we collected renal adipose tissue (RAT), epididymal adipose tissue (EAT), and TAPA samples. On all samples, we measured mRNA levels encoding for proinflammatory cytokines (TNFα, IL-6, IL-1ß, MCP-1). Our results showed an increase in mRNA MCP-1, TNF and IL-6 in the adipose tissue around atherosclerotic plaques, an increase that was greater in diabetics than in non-diabetic subjects; we noted for the mRNA of MCP-1 in the TAPAp, 3.49×10-2±1.17×10-2ng/ug 18S in diabetic patients compared to 7.26×10-3±1.00×10-3ng/ug 18S (**P<0.01) in non-diabetic patients. In the obese Zucker rat, we found a significant increase in IL-6 in TAPA in obese animals compared to the corresponding controls (4.24×10-5±1.75×10-6ng/µg 18S vs 1.29×10-5±1.55×10-6ng/ug 18S). In stressed rats, we recorded a TNFα mRNA increase in the PVAT and EAT in the stressed rats compared to fatty tissue of control animals, we note respectively, 7.52×10-3±2.8×10-3ng/µg 18S vs 2.62×10-3±0.57×10-3ng/18S and 4.78×10-3±1.52×10-3ng/µg 18S vs 2.02×10-3±0.3×10-3ng/ug 18S. In summary, our work shows an inflammatory state of the TAPA surrounding the atheromatous plaques in diabetic patients. An obesity or stress state promotes an inflammatory profile of PVAT.

The kinetics of angiotensin-I metabolism in human carotid atheroma: An emerging role for angiotensin (1-7).

AIM: Local levels of angiotensin peptides depend on their rates of production and degradation, which induce proatherogenic or atheroprotective effects. Here, we reveal the kinetics of Angiotensin-I metabolism in paired early and advanced atherosclerotic lesions. METHODS: Lesions were spiked with labeled Ang-I* and supernatants withdrawn after 0, 10, 20, 40 and 80min. The concentration of produced Ang-II*, Ang-III*, Ang-IV* and Ang-(1-7)* peptides were measured using multiple reaction monitoring mass spectrometry coupled to ultra-performance liquid chromatography, normalized to tissue weight and initial [Ang-I*]. RESULTS: Ang-(1-7)* was the major angiotensin peptide produced, showing increased levels in both tissue types, with 2-3 fold lower levels in advanced compared to early lesions. In contrast, Ang-II* was 2-3 fold higher in advanced compared to early lesions, showing a decrease between 0 and 40min then an increase at 80min in both tissue types. The levels of Ang-IV were stable in both tissue types across all time points. Finally, Ang-III was non-detectable in both lesions across all time points. CONCLUSION: Our results suggest that progression of atherosclerosis depends on the increased levels of Ang-II along with the decreased levels of Ang-(1-7), which supports the use of Ang-(1-7) along with Angiotensin type-1 receptor (AT1R) blockers.

[Vascular calcifications, the hidden side effects of vitamin K antagonists]. / Les calcifications vasculaires sous anti-vitamines K : un effet indésirable méconnu.

Despite the availability of new oral anticoagulants, vitamin K antagonists (VKA, such as fluindione, acenocoumarol or warfarin) remain currently the goal standard medicines for oral prevention or treatment of thromboembolic disorders. They inhibit the cycle of the vitamin K and its participation in the enzymatic gamma-carboxylation of many proteins. The VKA prevent the activation of the vitamin K-dependent blood clotting factors limiting thus the initiation of the coagulation cascade. But other proteins are vitamin K-dependent and also remain inactive in the presence of VKA. This is the case of matrix Gla-protein (MGP), a protein that plays a major inhibitory role in the development of vascular calcifications. Several experimental and epidemiological results suggest that the use of the VKA could promote the development of vascular calcifications increasing thus the cardiovascular risk. This risk seems to be higher in patients with chronic kidney disease or mellitus diabetes who are more likely to develop vascular calcifications, and may be due to a decrease of the MGP activity. This review aims at summarizing the data currently available making vascular calcifications the probably underestimated side effects of VKA.

Locus Coeruleus Dysfunction in Transgenic Rats with Low Brain Angiotensinogen.

AIMS: Transgenic TGR(ASrAOGEN)680 (TGR) rats with specific downregulation of glial angiotensinogen (AOGEN) synthesis develop cardiovascular deficits, anxiety, altered response to stress, and depression. Here, we evaluated whether these deficits are associated with alteration of the integrity of the noradrenergic system originating from locus coeruleus (LC) neurons. METHODS: Adult TGR rats were compared to control Sprague Dawley rats in terms of the following: tissue levels of transcripts encoding noradrenergic markers, tissue tyrosine hydroxylase (TH) protein level, in vivo TH activity, density of TH-containing fibers, behavioral response to novelty, locomotor activity, and polysomnography. RESULTS: TH expression was increased in the LC of TGR rats compared to controls. In LC terminal fields, there was an increase in density of TH-containing fibers in TGR rats that was associated with an elevation of in vivo TH activity. TGR rats also displayed locomotor hyperactivity in response to novelty. Moreover, polysomnographic studies indicated that daily paradoxical sleep duration was increased in TGR rats and that the paradoxical sleep rebound triggered by total sleep deprivation was blunted in these rats. CONCLUSIONS: Altogether, these results suggest that disruption of astroglial AOGEN synthesis leads to cardiovascular, cognitive, behavioral, and sleep disorders that might be partly due to LC dysfunction.

Atlas of tissue renin-angiotensin-aldosterone system in human: A transcriptomic meta-analysis.

Tissue renin-angiotensin-aldosterone system (RAAS) has attracted much attention because of its physiological and pharmacological implications; however, a clear definition of tissue RAAS is still missing. We aimed to establish a preliminary atlas for the organization of RAAS across 23 different normal human tissues. A set of 37 genes encoding classical and novel RAAS participants including gluco- and mineralo-corticoids were defined as extended RAAS (extRAAS) system. Microarray data sets containing more than 10 normal tissues were downloaded from the GEO database. R software was used to extract expression levels and construct dendrograms of extRAAS genes within each data set. Tissue co-expression modules were then extracted from reproducible gene clusters across data sets. An atlas of the maps of tissue-specific organization of extRAAS was constructed from gene expression and coordination data. Our analysis included 143 data sets containing 4933 samples representing 23 different tissues. Expression data provided an insight on the favored pathways in a given tissue. Gene coordination indicated the existence of tissue-specific modules organized or not around conserved core groups of transcripts. The atlas of tissue-specific organization of extRAAS will help better understand tissue-specific effects of RAAS. This will provide a frame for developing more effective and selective pharmaceuticals targeting extRAAS.

R Wave in aVL Lead is a Robust Index of Left Ventricular Hypertrophy: A Cardiac MRI Study.

BACKGROUND: In patients free from overt cardiac disease, R wave in aVL lead (RaVL) is strongly correlated with left ventricular mass index (LVMI) assessed by transthoracic echocardiography. The aim of the present study was to extend this finding to other settings (cardiomyopathy or conduction disorders), by comparing ECG criteria of left ventricular hypertrophy (LVH) to cardiac MRI (CMR). METHODS: In 501 patients, CMR and ECG were performed within a median-period of 5 days. CMR LVH cut-offs used were 83 g/m2 in men and 67 g/m2 in women. RESULTS: RaVL was independently correlated with LVMI in patients with or without myocardial infarction (MI) (N = 300 and N = 201, respectively). SV3 was independently correlated with LVMI and LV enlargement only in patients without MI. In the whole cohort, RaVL had area under receiver-operating characteristic curve of 0.729 (specificity 98.3%, sensitivity 19.6%, optimal cut-off 1.1 mV). The performance of RaVL was remarkable in women, in Caucasians, and in the presence of right bundle branch block. It decreased in case of MI. Overall, it is proposed that below 0.5 mV and above 1.0 mV, RaVL is sufficient to exclude or establish LVH. Between 0.5 and 1 mV, composite indices (Cornell voltage or product) should be used. Using this algorithm allowed classifying appropriately 85% of the patients. CONCLUSIONS: Our results showed that RaVL is a good index of LVH with a univocal threshold of 1.0 mV in various clinical conditions. SV3 may be combined to RaVL in some conditions, namely LV enlargement to increase its performance.

Decreased plasma prorenin levels in primary aldosteronism: potential diagnostic implications.

AIM: Primary aldosteronism could exert a negative feedback on prorenin secretion, of possibly different magnitude, whether it is related to an aldosterone-producing adenoma (APA) or an idiopathic hyperaldosteronism (IHA). The objectives of this study were to evaluate the level of prorenin in three subgroups: APA, IHA, and essential hypertension; and the performance of the aldosterone-to-prorenin ratio (APR) for the diagnosis of an APA. METHODS: Seven hundred and forty-six hypertensive patients with a standardized work-up, including a prorenin measurement, were considered. Ninety-six patients without neutral treatment and 38 patients with other forms of secondary hypertension were excluded. APA and IHA were categorized according to computed tomography scan, adrenal venous sampling, pathological analysis and improvement of hypertension after surgery. RESULTS: Thirty-five patients had a diagnosis of APA, 57 of IHA and 504 of essential hypertension. Prorenin was lower in APA and IHA than in essential hypertension (32.9, 40.4 and 50.3  pg/ml, respectively; P < 0.001). APR was higher in patients with APA and IHA than in those with essential hypertension (24.0, 11.8, and 4.0  pmol/l per pg/ml, respectively; P < 0.001). The APR was more discriminant than the aldosterone-to-renin ratio to identify APA compared to IHA (area under the receiver operating curve at 0.750 and 0.639, respectively; P = 0.04). The optimal cut-off values were 22  pmol/l per pg/ml for APR (sensitivity 57.0%, specificity 93.0%) and 440  pmol/l per pg/ml for aldosterone-to-renin ratio (sensitivity 54.3%, specificity 82.5%). CONCLUSION: Primary aldosteronism and particularly its most caricatural form, that is APA, seems associated with a lower level of prorenin than essential hypertension. The APR could be included in the diagnostic strategy of APA.

Baroreceptor stimulation for resistant hypertension: first implantation in France and literature review.

Despite a wide choice of effective antihypertensive treatments, blood pressure (BP) in roughly half of hypertensive subjects is not controlled. Resistant hypertension is defined as an uncontrolled BP despite optimal doses of three antihypertensive treatments, including a diuretic. After confirmation of resistant BP using home BP measurement or 24-hour ambulatory BP monitoring (ABPM), patients usually go through a work-up to rule out secondary hypertension. If secondary hypertension is ruled out, the recent European guidelines on hypertension consider baroreceptor stimulation or renal denervation to be possible options. The prevalence of resistant primary hypertension may reach up to 10% in specialized centres. The two proposed non-pharmacological therapeutic strategies have been developed recently to inhibit sympathetic overactivity in resistant hypertension. Among them, baroreceptor activation therapy (BAT) is an innovative approach that interferes with baroreflex function. The first-generation BAT device (Rheos(®); CVRx, Inc., Minneapolis, MN, USA) demonstrated good efficacy in lowering office BP and ABPM, but had an insufficient safety profile due to complex surgery. The second-generation BAT device (Barostim neo™ system; CVRx, Inc.) seems to share the same BP-lowering efficacy but has a better safety profile. We report the first French case of baroreceptor stimulation for hypertension using the Barostim neo™ system. We also discuss the pathophysiological features of and current levels of evidence for this technique.

Mutual amplification of corticosteroids and angiotensin systems in human vascular smooth muscle cells and carotid atheroma.

UNLABELLED: The involvement of the renin-angiotensin-aldosterone system (RAAS) and cortisol in increased cardiovascular risk is well known. If numerous relationships between RAAS and corticosteroids have been described, their interactions within the arterial wall, especially during the transdifferentiation of vascular smooth muscle cells (VSMCs) and the atheroma formation, are not established. Here, we clarified the relationships between mRNA levels of corticosteroid and angiotensin system components using cortisol, fludrocortisone, and angiotensin II treatments of cultured VSMCs maintained in a contractile phenotype or induced to a lipid storing phenotype. We then determined the quantitative relationships between the mRNA content of these components measured with reverse transcription polymerase chain reaction (RT-PCR), in the atheroma plaque and nearby macroscopically intact tissue (MIT) from 27 human carotid endarterectomy samples. In both VSMC phenotypes, cortisol markedly increased both angiotensinogen (AGT) and AT1-receptor (AT1R) mRNA levels. These effects of cortisol were mediated via glucocorticoid receptor-α (GRα) without any illicit activation of the mineralocorticoid receptor (MR). Angiotensin II increased GRα, 11ßHSD1, CYP11B1, as well as CYP11B2 mRNAs and decreased AT1R in contractile VSMC; only GRα and CYP11B2 were increased in lipid storing VSMCs, while MR and AGT mRNAs decreased. In endarterectomy specimens, positive correlations between mRNA levels of AGT and aldosterone synthase or 11ßHSD1 in MIT and of AT1R and MR in atheroma were detected. The arterial tissue angiotensin system is a target for local glucocorticoids and arterial glucocorticoids for angiotensin II. Both systems appear activated in lipid storing VSMCs and strongly correlated in vivo, and their mutual amplification may contribute to the development of atheroma. KEY MESSAGE: Cortisol increases angiotensin II signaling in VSMCs via GRα. Angiotensin II stimulates cortisol signaling through increased GRα and 11ß-HSD1. Corticoid and angiotensin receptors are strongly correlated in the arterial wall. These correlations are maintained at different stages of atheroma development. An auto-amplification loop between angiotensin and cortisol signaling favors atherogenesis.

Robust coordination of cardiac functions from gene co-expression reveals a versatile combinatorial transcriptional control.

The necessary overall coordination of cardiac cellular functions is little known at the mRNA level. Focusing on energy production and cardiac contraction, we analyzed microarray data from heart tissue obtained in groups of mice and rats in normal conditions and with a left ventricular dysfunction. In each group and for each function, we identified genes positively or negatively correlated with numerous genes of the function, which were called coordinated or inversely coordinated with the function. The genes coordinated with energy production or cardiac contraction showed the coupling of these functions in all groups. Among coordinated or inversely coordinated genes common to the two functions, we proposed a fair number of transcriptional regulators as potential determinants of the energy production and cardiac contraction coupling. Although this coupling was constant across the groups and unveiled a stable gene core, the combinations of transcriptional regulators were very different between the groups, including one half that has never been linked to heart function. These results highlighted the stable coordination of energy production or cardiac contraction at the mRNA level, and the combinatorial and versatile nature of potential transcriptional regulation. In addition, this work unveiled new transcriptional regulators potentially involved in normal or altered cardiac functional coupling.

Computational identification of potential transcriptional regulators of TGF-ß1 in human atherosclerotic arteries.

TGF-ß is protective in atherosclerosis but deleterious in metastatic cancers. Our aim was to determine whether TGF-ß transcriptional regulation is tissue-specific in early atherosclerosis. The computational methods included 5 steps: (i) from microarray data of human atherosclerotic carotid tissue, to identify the 10 best co-expressed genes with TGFB1 (TGFB1 gene cluster), (ii) to choose the 11 proximal promoters, (iii) to predict the TFBS shared by the promoters, (iv) to identify the common TFs co-expressed with the TGFB1 gene cluster, and (v) to compare the common TFs in the early lesions to those identified in advanced atherosclerotic lesions and in various cancers. Our results show that EGR1, SP1 and KLF6 could be responsible for TGFB1 basal expression, KLF6 appearing specific to atherosclerotic lesions. Among the TFs co-expressed with the gene cluster, transcriptional activators (SLC2A4RG, MAZ) and repressors (ZBTB7A, PATZ1, ZNF263) could be involved in the fine-tuning of TGFB1 expression in atherosclerosis.

R wave in aVL lead: an outstanding ECG index in hypertension.

OBJECTIVES: The voltage of R wave in lead aVL (RaVL) seems to be more tightly correlated with left ventricular mass and cardiovascular events than any other ECG criterium of left ventricular hypertrophy. We hypothesized that RaVL could be an independent predictor of all-cause and cardiovascular death in hypertensive individuals. METHODS: The baseline clinical and biological variables as well as ECG recordings were analyzed in a prospective cohort of 589 hypertensive individuals. RESULTS: After 10 years of follow-up, we observed 95 deaths of which 53 had a cardiovascular cause. The optimal RaVL voltages to predict all-cause and cardiovascular mortality were 0.8 and 0.6  mV, respectively. In a multivariate adjusted Cox model, having an RaVL voltage superior to these cutoffs was associated with increased risks of all-cause death [hazard ratio: 2.04, 95% confidence interval (CI): (1.30-3.22)] and of cardiovascular death [hazard ratio: 2.89, 95% CI: (1.47-5.68)]. In the whole cohort and with the same adjusted Cox regression model, each 0.1  mV increment would increase the risk of all-cause death by 1.07 times [95% CI: (1.02-1.12)] and that of cardiovascular death by 1.13 times [95% CI: (1.06-1.20)]. After excluding in turn patients with positive Sokolow index, Cornell voltage, or Cornell product, the results remained statistically significant, meaning that RaVL was still able to pick-up high-risk patients when other classical and more sophisticated indices were not observable. CONCLUSION: The present results strengthen previous reports that demonstrated a strong role of RaVL voltage in risk stratification in hypertension.

Diastolic blood pressure, aortic atheroma, and prognosis in hypertension: new insights into a complex association.

OBJECTIVES: Our study aimed at determining the interaction between the prognostic value of diastolic blood pressure (DBP) and aortic atherosclerosis (ATS). BACKGROUND: With aging, equal systolic blood pressures (SBPs) become associated with low DBPs; i.e., high pulse pressures (PPs) become associated with a high risk of cardiovascular death. This association is usually ascribed to aortic stiffening with age but the precise impact of low DBP per se is yet uncertain. METHODS: 938 hypertensive patients recruited in the seventies had an aortic ATS score at pretreatment aortography. All-cause and cardiovascular deaths were assessed 20 years later. The prognostic values of DBP and SBP were assessed by a multivariate Cox regression model and their interactions with ATS examined. RESULTS: In the presence of ATS, an increase of 10 mmHg in DBP was associated with a protective effect: hazard ratios 0.84 [0.72-0.99] for cardiovascular death and 0.88 [0.78-1.00] for all-cause death. However, in the absence of ATS, DBP had no prognostic value: hazard ratios 1.05 [0.89-1.23] for cardiovascular death and 0.99 [0.88-1.11] for all-cause death (p for interaction: 0.061 and 0.087, respectively). No interaction was found between SBP and ATS (p for interaction > 0.40). CONCLUSIONS: The prognostic values of DBP and aortic atheroma are not superimposable; yet, they are tightly connected: a low DBP is disadvantageous only in the presence of a pathologic aorta. Aortic atherosclerosis may explain, at least partly, in some high risk populations, the J-shape of the already reported DBP-outcome relationship.

Avidity and positive allosteric modulation/cooperativity act hand in hand to increase the residence time of bivalent receptor ligands.

Bivalent ligands bear two target-binding pharmacophores. Their simultaneous binding increases their affinity (avidity) and residence time. They become 'bitopic' when the binding sites at the target permit the pharmacophores the exert allosteric modulation of each other's affinity and/or activity. Present simulations reveal that positive cooperativity exacerbates these phenomena, whereas negative cooperativity curtails them, irrespective of whether the association or dissociation rates of the individual pharmacophores are affected. Positive cooperativity delays the attainment of equilibrium binding, yielding 'hemi-equilibrium' conditions and only apparent affinity constants under usual experimental conditions. Monovalent ligands that bind to one of the target sites decrease the bitopic ligand's residence time concentration-wise; their potency depends on their association rate and thereon acting cooperativity rather than on affinity. This stems from the repetitive, very fast reformation of fully bound bitopic ligand-target complexes by rebinding of freshly dissociated pharmacophores. These studies deal with kinetic binding properties (of increasing interest in pharmacology) of bitopic ligands (a promising avenue in medicinal chemistry).