Auto-amplification of cortisol actions in human carotid atheroma is linked to arterial remodeling and stroke

Glucocorticoids: Fuelling the Fire of Atherosclerosis or Therapeutic Extinguishers?

Glucocorticoids are steroid hormones with key roles in the regulation of many physiological systems including energy homeostasis and immunity. However, chronic glucocorticoid excess, highlighted in Cushing's syndrome, is established as being associated with increased cardiovascular disease (CVD) risk. Atherosclerosis is the major cause of CVD, leading to complications including coronary artery disease, myocardial infarction and heart failure. While the associations between glucocorticoid excess and increased prevalence of these complications are well established, the mechanisms underlying the role of glucocorticoids in development of atheroma are unclear. This review aims to better understand the importance of glucocorticoids in atherosclerosis and to dissect their cell-specific effects on key processes (e.g., contractility, remodelling and lesion development). Clinical and pre-clinical studies have shown both athero-protective and pro-atherogenic responses to glucocorticoids, effects dependent upon their multifactorial actions. Evidence indicates regulation of glucocorticoid bioavailability at the vasculature is complex, with local delivery, pre-receptor metabolism, and receptor expression contributing to responses linked to vascular remodelling and inflammation. Further investigations are required to clarify the mechanisms through which endogenous, local glucocorticoid action and systemic glucocorticoid treatment promote/inhibit atherosclerosis. This will provide greater insights into the potential benefit of glucocorticoid targeted approaches in the treatment of cardiovascular disease.

Impact of cortisol on blood pressure and hypertension-mediated organ damage in hypertensive patients

OBJECTIVES

Patients with overt and subclinical Cushing's syndrome frequently develop hypertension, metabolism disorders, and atherosclerotic lesions. The aim of the present study was to test the association between cortisol and blood pressure (BP), organ damage, and metabolic parameters in hypertensive patients without hypercortisolism.

METHODS

After exclusion of patients treated with corticosteroids or with Cushing's syndrome, the cohort included 623 hypertensive patients (mean ± SD age 50.3 ± 15.4 years, 50.9% men, median 24-h BP 146/88 mmHg) with an extended work-up (lipid profile, hypertension-mediated organ damage). Cortisol secretion was assessed by plasma cortisol at 0800 and 1600 h, and by 24-h urinary free cortisol (24 h UFC) normalized if required to urine creatinine (UFC/U creat).

RESULTS

Plasma cortisol at 1600 h, 24 h-UFC, and UFC/U creat were significantly and positively correlated with daytime, night-time, and 24-h SBP; plasma cortisol at 0800 h was not associated with BP. The strongest correlations were observed in the subgroup of aged more than 50 years (correlation coefficients between 0.23 and 0.28). These correlations remained after adjustment on plasma aldosterone. Metabolic parameters were weakly associated with cortisol. Arterial stiffness (central pulse pressure and pulse wave velocity), plasma NT-proBNP, and microalbuminuria were significantly correlated with 24 h UFC, UFC/U creat, and plasma cortisol at 1600 h.

CONCLUSION

Cortisol influences weakly the level of BP independently from plasma aldosterone in hypertensive patients, particularly in older patients, and that there was weak association with HMOD. It may, therefore, be of interest to test specific treatments targeting cortisol excess in selected hypertensive patients.

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.

Local Angiotensin Pathways in Human Carotid Atheroma: Towards a Systems Biology Approach

We will summarize the data we have obtained in human carotid artery concerning the organization of an extended local renin angiotensin aldosterone system and its variations at different stages of atheroma. In a system view, we propose a model where concomitant increase in angiotensin and glucocorticoid signaling is induced and amplified in VSMC while vascular smooth muscle cells transdifferentiate toward a lipid storing phenotype.

Maternal food restriction modulates cerebrovascular structure and contractility in adult rat offspring: effects of metyrapone

Although the effects of prenatal undernutrition on adult cardiovascular health have been well studied, its effects on the cerebrovascular structure and function remain unknown. We used a pair-fed rat model of 50% caloric restriction from day 11 of gestation to term, with ad libitum feeding after birth. We validated that maternal food restriction (MFR) stress is mediated by glucocorticoids by administering metyrapone, a corticosterone synthesis inhibitor, to MFR mothers at day 11 of gestation. At age 8 mo, offspring from Control, MFR, and MFR + Metyrapone groups were killed, and middle cerebral artery (MCA) segments were studied using vessel-bath myography and confocal microscopy. Colocalization of smooth muscle α-actin (SMαA) with nonmuscle (NM), SM1 and SM2 myosin heavy-chain (MHC) isoforms was used to assess smooth muscle phenotype. Our results indicate that artery stiffness and wall thickness were increased, pressure-evoked myogenic reactivity was depressed, and myofilament Ca(2+) sensitivity was decreased in offspring of MFR compared with Control rats. MCA from MFR offspring exhibited a significantly greater SMαA/NM colocalization, suggesting that the smooth muscle cells had been altered toward a noncontractile phenotype. MET significantly reversed the effects of MFR on stiffness but not myogenic reactivity, lowered SMαA/NM colocalization, and increased SMαA/SM2 colocalization. Together, our data suggest that MFR alters cerebrovascular contractility via both glucocorticoid-dependent and glucocorticoid-independent mechanisms.

Modulation of 11β-hydroxysteroid dehydrogenase as a strategy to reduce vascular inflammation

Atherosclerosis is a chronic inflammatory disease in which initial vascular damage leads to extensive macrophage and lymphocyte infiltration. Although acutely glucocorticoids suppress inflammation, chronic glucocorticoid excess worsens atherosclerosis, possibly by exacerbating systemic cardiovascular risk factors. However, glucocorticoid action within the lesion may reduce neointimal proliferation and inflammation. Glucocorticoid levels within cells do not necessarily reflect circulating levels due to pre-receptor metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSDs). 11β-HSD2 converts active glucocorticoids into inert 11-keto forms. 11β-HSD1 catalyses the reverse reaction, regenerating active glucocorticoids. 11β-HSD2-deficiency/inhibition causes hypertension, whereas deficiency/inhibition of 11β-HSD1 generates a cardioprotective lipid profile and improves glycemic control. Importantly, 11β-HSD1-deficiency/inhibition is atheroprotective, whereas 11β-HSD2-deficiency accelerates atherosclerosis. These effects are largely independent of systemic risk factors, reflecting modulation of glucocorticoid action and inflammation within the vasculature. Here, we consider whether evidence linking the 11β-HSDs to vascular inflammation suggests these isozymes are potential therapeutic targets in vascular injury and atherosclerosis.