Lack of Renal 11 Beta-Hydroxysteroid Dehydrogenase Type 2 at Birth, a Targeted Temporal Window for Neonatal Glucocorticoid Action in Human and Mice

International audienceBackground Glucocorticoid hormones play a major role in fetal organ maturation. Yet, excessive glucocorticoid exposure in utero can result in a variety of detrimental effects, such as growth retardation and increased susceptibility to the development of hypertension. To protect the fetus, maternal glucocorticoids are metabolized into inactive compounds by placental 11beta-hydroxysteroid dehydrogenase type2 (11βHSD2). This enzyme is also expressed in the kidney, where it prevents illicit occupation of the mineralocorticoid receptor by glucocorticoids. We investigated the role of renal 11βHSD2 in the control of neonatal glucocorticoid metabolism in the human and mouse. Methods Cortisol (F) and cortisone (E) concentrations were measured in maternal plasma, umbilical cord blood and human newborn urine using HPLC. 11βHSD2 activity was indirectly assessed by comparing the F/E ratio between maternal and neonatal plasma (placental activity) and between plasma and urine in newborns (renal activity). Direct measurement of renal 11βHSD2 activity was subsequently evaluated in mice at various developmental stages. Renal 11βHSD2 mRNA and protein expression were analyzed by quantitative RT-PCR and immunohistochemistry during the perinatal period in both species. Results We demonstrate that, at variance with placental 11βHSD2 activity, renal 11βHSD2 activity is weak in newborn human and mouse and correlates with low renal mRNA levels and absence of detectable 11βHSD2 protein. Conclusions We provide evidence for a weak or absent expression of neonatal renal 11βHSD2 that is conserved among species. This temporal and tissue-specific 11βHSD2 expression could represent a physiological window for glucocorticoid action yet may constitute an important predictive factor for adverse outcomes of glucocorticoid excess through fetal programming

Chymase-Dependent Generation of Angiotensin II from Angiotensin-(1-12) in Human Atrial Tissue

Since angiotensin-(1-12) [Ang-(1-12)] is a non-renin dependent alternate precursor for the generation of cardiac Ang peptides in rat tissue, we investigated the metabolism of Ang-(1-12) by plasma membranes (PM) isolated from human atrial appendage tissue from nine patients undergoing cardiac surgery for primary control of atrial fibrillation (MAZE surgical procedure). PM was incubated with highly purified 125I-Ang-(1-12) at 37°C for 1 h with or without renin-angiotensin system (RAS) inhibitors [lisinopril for angiotensin converting enzyme (ACE), SCH39370 for neprilysin (NEP), MLN-4760 for ACE2 and chymostatin for chymase; 50 µM each]. 125I-Ang peptide fractions were identified by HPLC coupled to an inline γ-detector. In the absence of all RAS inhibitor, 125I-Ang-(1-12) was converted into Ang I (2±2%), Ang II (69±21%), Ang-(1-7) (5±2%), and Ang-(1-4) (2±1%). In the absence of all RAS inhibitor, only 22±10% of 125I-Ang-(1-12) was unmetabolized, whereas, in the presence of the all RAS inhibitors, 98±7% of 125I-Ang-(1-12) remained intact. The relative contribution of selective inhibition of ACE and chymase enzyme showed that 125I-Ang-(1-12) was primarily converted into Ang II (65±18%) by chymase while its hydrolysis into Ang II by ACE was significantly lower or undetectable. The activity of individual enzyme was calculated based on the amount of Ang II formation. These results showed very high chymase-mediated Ang II formation (28±3.1 fmol×min−1×mg−1, n = 9) from 125I-Ang-(1-12) and very low or undetectable Ang II formation by ACE (1.1±0.2 fmol×min−1×mg−1). Paralleling these findings, these tissues showed significant content of chymase protein that by immunocytochemistry were primarily localized in atrial cardiac myocytes. In conclusion, we demonstrate for the first time in human cardiac tissue a dominant role of cardiac chymase in the formation of Ang II from Ang-(1-12)

ACE2-Mediated Reduction of Oxidative Stress in the Central Nervous System Is Associated with Improvement of Autonomic Function

Oxidative stress in the central nervous system mediates the increase in sympathetic tone that precedes the development of hypertension. We hypothesized that by transforming Angiotensin-II (AngII) into Ang-(1–7), ACE2 might reduce AngII-mediated oxidative stress in the brain and prevent autonomic dysfunction. To test this hypothesis, a relationship between ACE2 and oxidative stress was first confirmed in a mouse neuroblastoma cell line (Neuro2A cells) treated with AngII and infected with Ad-hACE2. ACE2 overexpression resulted in a reduction of reactive oxygen species (ROS) formation. In vivo, ACE2 knockout (ACE2−/y) mice and non-transgenic (NT) littermates were infused with AngII (10 days) and infected with Ad-hACE2 in the paraventricular nucleus (PVN). Baseline blood pressure (BP), AngII and brain ROS levels were not different between young mice (12 weeks). However, cardiac sympathetic tone, brain NADPH oxidase and SOD activities were significantly increased in ACE2−/y. Post infusion, plasma and brain AngII levels were also significantly higher in ACE2−/y, although BP was similarly increased in both genotypes. ROS formation in the PVN and RVLM was significantly higher in ACE2−/y mice following AngII infusion. Similar phenotypes, i.e. increased oxidative stress, exacerbated dysautonomia and hypertension, were also observed on baseline in mature ACE2−/y mice (48 weeks). ACE2 gene therapy to the PVN reduced AngII-mediated increase in NADPH oxidase activity and normalized cardiac dysautonomia in ACE2−/y mice. Altogether, these data indicate that ACE2 gene deletion promotes age-dependent oxidative stress, autonomic dysfunction and hypertension, while PVN-targeted ACE2 gene therapy decreases ROS formation via NADPH oxidase inhibition and improves autonomic function. Accordingly, ACE2 could represent a new target for the treatment of hypertension-associated dysautonomia and oxidative stress

Developmental effect of antenatal exposure to betamethasone on renal angiotensin II activity in the young adult sheep

Antenatal corticosteroids may have long-term effects on renal development which have not been clearly defined. Our objective was to compare the responses to intrarenal infusions of ANG II in two groups of year-old, male sheep: one group exposed to a clinically relevant dose of betamethasone before birth and one not exposed. We wished to test the hypothesis that antenatal steroid exposure would enhance renal responses to ANG II in adult life. Six pairs of male sheep underwent unilateral nephrectomy and renal artery catheter placement. The sheep were infused for 24 h with ANG II or with ANG II accompanied by blockade of the angiotensin type 1 (AT1) or type 2 (AT2) receptor. Baseline mean arterial blood pressure among betamethasone-exposed sheep was higher than in control animals (85.8 ± 2.2 and 78.3 ± 1.0 mmHg, respectively, P = 0.003). Intrarenal infusion of ANG II did not increase systemic blood pressure (P ≥ 0.05) but significantly decreased effective renal plasma flow and increased renal artery resistance (P < 0.05). The decrease in flow and increase in resistance were significantly greater in betamethasone- compared with vehicle-exposed sheep (betamethasone P < 0.05, vehicle P ≥ 0.05). This effect appeared to be mediated by a heightened sensitivity to the AT1 receptor among betamethasone-exposed sheep. Sodium excretion initially decreased in both groups during ANG II infusion; however, a rebound was observed after 24 h. AT1 blockade was followed by a significant rebound after 24 h in both groups. AT2 blockade blunted the 24-h rebound effect among the vehicle-exposed sheep compared with the betamethasone-exposed sheep. In conclusion, antenatal corticosteroid exposure appears to modify renal responsiveness to ANG II by increasing AT1- and decreasing AT2 receptor-mediated actions particularly as related to renal blood flow and sodium excretion

Investigation of the psychometric properties of the Inclusion Body Myositis Functional Rating Scale using Rasch analysis

INTRODUCTION: The IBMRFS is a 10 item clinician rated ordinal scale developed for people with inclusion body myositis. METHODS: Single observations of the IBMFRS were collected from 132 patients. Following Rasch analysis, modifications were made to the scale to optimise fit to the Rasch model, while maintaining clinical validity and utility. RESULTS: The original IBMFRS did not fit the assumptions of the Rasch model due to multidimensionality of the scale. Items demonstrated local dependence, disordered step thresholds, and differential item functioning. Deconstructing the scale into upper limb (IBMFRS-UL) and lower limb (IBMFRS-LL) scales improved fit to the Rasch model. A 9 item scale, with the swallowing item removed, (IBMFRS-9) remained multidimensional but demonstrated the ability to discriminate patients along the severity continuum. IBMFRS-UL, IBMFRS-LL and IBMFRS-9 scores were transformed to a 0-100 scale for comparability. DISCUSSION: This analysis has led to the development of three optimised versions of the IBMFRS. This article is protected by copyright. All rights reserved