Expression Of Renin-angiotensin System Genes Research Articles

Regulation of the renin-angiotensin system (RAS) in BeWo and HTR-8/SVneo trophoblast cell lines

ObjectivesThe renin-angiotensin system (RAS) is implicated in placentation. We determined which RAS pathways are present in two trophoblast cell lines (HTR-8/SVneo and BeWo cells) and the effects of cAMP, which stimulates renal renin. Study designThe effect of cAMP on RAS gene expression and on prorenin and angiotensin peptides in HTR-8/SVneo and BeWo cells were investigated. ResultsIn HTR-8/SVneo cells, prorenin mRNA (REN) and protein, (pro)renin receptor (ATP6AP2) and angiotensin II type 1 receptor (AGTR1) were stimulated by cAMP (P < 0.05, P < 0.05, P < 0.001 and P < 0.05, respectively). HTR-8/SVneo cells also expressed angiotensinogen (AGT) and angiotensin converting enzyme 1 (ACE1), but did not express AGTR2 or ACE2 nor the Ang 1-7 receptor (MAS1).BeWo cells did not express REN, and REN was not inducible by cAMP, but cAMP increased ACE2 and MAS1 (both P < 0.05) and decreased AGT (P < 0.05). BeWo cells expressed AGT, ACE1, ACE2 and MAS1 but not ATP6AP2, AGTR1 nor AGTR2.There was net destruction of Ang II in media from HTR-8/SVneo and BeWo incubations and net production of Ang 1-7 by BeWo and untreated HTR-8/SVneo cells. ConclusionHTR-8/SVneo cells express REN and produce prorenin as well as expressing other RAS genes likely to regulate Ang II/AT1R interactions and respond to cAMP, like renal renin-secreting cells. They are more similar to early gestation placentae and are therefore useful for studying effects of renin/ACE/Ang II/AT1R on cell function.BeWo cells express the ACE2/Ang 1-7/Mas pathway, which is sensitive to cAMP and therefore are useful for studying the effects of ACE2/Ang 1-7/Mas on trophoblast function.

Dietary Phosphate Binding and Loading Alter Kidney Angiotensin-Converting Enzyme mRNA and Protein Content in 5/6 Nephrectomized Rats

Background: Vitamin D receptor activation with paricalcitol can modulate the transcription of renin-angiotensin system components in the surgical 5/6 nephrectomy rat model (5/6 NX) of chronic renal insufficiency. We tested the hypothesis whether dietary modification of phosphate influences kidney renin-angiotensin system gene expression at the mRNA level in 5/6 NX rats. Methods: Fifteen weeks after surgery, rats were given control diet (0.3% calcium, 0.5% phosphate), phosphate-lowering diet (3% calcium as carbonate) or high-phosphate diet (1.5%) for 12 weeks. Sham-operated rats were on control diet. Results: Blood pressure, plasma phosphate, parathyroid hormone, glomerulosclerosis, tubulointerstitial damage, and FGF-23 were increased in remnant kidney rats, whereas creatinine clearance was decreased. Phosphate, parathyroid hormone, glomerulosclerosis, tubulointerstitial damage, and FGF-23 were further elevated by the high-phosphate diet, but were reduced by the phosphate-lowering diet. Plasma calcium was increased with the phosphate-lowering diet and decreased with the high-phosphate diet. Remnant kidney rats on control diet showed upregulated kidney angiotensin-converting enzyme (ACE) and angiotensin (Ang) IV receptor (AT₄) transcription, while ACE2, Ang II type 2 receptor and renin receptor transcription were downregulated in comparison with sham rats. Phosphate-lowering diet reduced whereas high-phosphate diet increased kidney ACE, and these effects were observed at both mRNA and protein levels. Dietary phosphate loading also resulted in lower AT_1a gene transcription. Conclusion: Dietary phosphate loading was associated with elevated kidney ACE expression, increased tissue damage and lower AT_1a transcription in 5/6 NX rats. Phosphate binding with 3% calcium carbonate had opposite effects on ACE and kidney damage.

Soya protein attenuates abnormalities of the renin–angiotensin system in adipose tissue from obese rats

Several metabolic disturbances during obesity are associated with adipose tissue-altered functions. Adipocytes contain the renin-angiotensin system (RAS), which regulates signalling pathways that control angiogenesis via Akt in an autocrine fashion. Soya protein (Soy) consumption modifies the gene expression pattern in adipose tissue, resulting in an improved adipocyte function. Therefore, the aim of the present work is to study whether dietary Soy regulates the expression of RAS and angiogenesis-related genes and its association with the phosphorylated state of Akt in the adipose tissue of obese rats. Animals were fed a 30% Soy or casein (Cas) diet containing 5 or 25% fat for 160d. mRNA abundance was studied in the adipose tissue, and Akt phosphorylation and hormone release were measured in the primary adipocyte culture. The present results show that Soy treatment in comparison with Cas consumption induces lower angiotensin release and increased insulin-stimulated Akt activation in adipocytes. Furthermore, Soy consumption varies the expression of RAS and angiogenesis-related genes, which maintain cell size and vascularity in the adipose tissue of rats fed a high-fat diet. Thus, adipocyte hypertrophy and impaired angiogenesis, which are frequently observed in dysfunctional adipose tissue, were avoided by consuming dietary Soy. Taken together, these findings suggest that Soy can be used as a dietary strategy to preserve adipocyte functionality and to prevent obesity abnormalities.

Renin-angiotensin system gene expression in the kidney and in the heart in hypertensive ISIAH rats

The content of mRNA of renin-angiotensin system (RAS) genes in the kidney and heart of hypertensive ISIAH and normotensive WAG rats was measured by the real-time PCR. Statistically significant decrease of RAS gene mRNA was registered in the kidney of ISIAH rats, including Ren (by 45%), Ace (43%), AT1A (34%), COX-2 (50%). In the myocardium AT1A mRNA expression decreased by 28% while Ace mRNA expression increased by 80%. These results demonstrate the reduction of renal RAS basal activity in the hypertensive ISIAH rats, and this allows us to consider the ISIAH rat, as a low-renin hypertensive strain. In support of this viewpoint, in the ISIAH rats, a two-fold increase in the connective tissue sodium concentration as well as statistically significant plasma sodium increase (from 136 +/- 0,25 micromol/l in WAG to 139 +/- 0,3 micromol/l in the ISIAH rats) were found. Our conclusion backed by a tendency of the ISIAH plasma aldosterone level decrease giving in sum a classical picture of a low-renin hypertensive state in the ISIAH rats. It was suggested that the formation of low-renin arterial hypertension in the ISIAH rats may depend on changes in kidney ion channels function. In addition, renal NO system alterations could be also involved in the pathogenesis of arterial hypertension in the ISIAH rats.

Epigenetics and Hypertension

Epigenetics refers to mechanisms for environment-gene interactions (mainly by methylation of DNA and modification of histones) that do not alter the underlying base sequence of the gene. This article reviews evidence for epigenetic contributions to hypertension. For example, DNA methylation at CpG islands and histone acetylation pathways are known to limit nephron development, thereby unmasking hypertension associated with exposure to a high-salt diet. Maternal water deprivation and protein deficiency are shown to increase expression of renin-angiotensin system genes in the offspring. The methylation pattern of a serine protease inhibitor gene in human placentas is shown to be a marker for preeclampsia-associated hypertension. Mental stress induces phenylethanolamine n-methyltransferase, which may act as a DNA methylase and mimic the gene-silencing effects of methyl CpG binding protein-2 on the norepinephrine transporter gene, which, in turn, may exaggerate autonomic responsiveness. A disrupter of telomeric silencing (Dot1) is known to modulate the expression of a connective-tissue growth-factor gene associated with blood vessel remodeling, which could alter vascular compliance and elastance. Dot1a also interacts with the Af9 gene to produce high sodium channel permeability and silences the hydroxysteroid dehydrogenase-11β2 gene, thereby preventing metabolism of cortisol to cortisone and overstimulating aldosterone receptors. These findings indicate targets for environment-gene interactions in various hypertensive states and in essential hypertension.

Antenatal maternal hypoxic stress: Adaptations of the placental renin-angiotensin system in the mouse

AbstractThe stress of Antenatal Maternal Hypoxia (AMH) can lead to a number of physiological and pathological changes in both mother and fetus, changes which can be linked to alterations in placental morphology and gene regulation. Recently, in the Brown Norway rat “model” of placental insufficiency, we reported alterations in placental renin-angiotensin system (RAS) genes. Moreover, AMH can lead to reduced oxygen availability to the fetus, similar to a state of placental insufficiency. Thus, in pregnant mice dams we tested the hypothesis that antenatal maternal hypoxic stress leads to alterations in the placental RAS. These alterations may, in part, account for the phenotypic changes in both pregnant mice dams as well as fetus and adult offspring. MethodsPregnant FVB/NJ mice dams were either maintained as controls, or exposed to 10.5% O2 for 48 h from 15.5 to 17.5 day post coitum. We then measured placental mRNA and protein expression of several RAS genes (n = 4 to 5; P < 0.05 was considered significant). ResultIn murine placenta: (1) angiotensinogen (AGT) mRNA was undetectable; however, AGT protein was detectable and increased significantly with AMH. (2) In AMH, although renin mRNA was reduced protein expression increased, in association with decreased microRNA (miRNA) 199b, which can lead to increased renin translation. (3) Also in AMH placenta, angiotensin converting enzyme (ACE) -1 mRNA was unaltered; however, protein expression increased significantly, in association with decreased miRNA 27a, which can result in increased ACE-1 translation. (4) In AMH placenta, ACE-2 mRNA was reduced significantly, whereas protein expression was significantly greater, in association with reduced miRNA 429. (5) In AMH placenta, angiotensin II type (AT) -1a receptor mRNA expression was unaltered while AT-1b receptor mRNA was undetectable in both groups. Moreover, AT-1 receptor protein expression was unchanged in response to AMH. (6) AT-2 receptor mRNA and proteins were undetectable in both groups. ConclusionThe normal murine placenta possesses several components of RAS, and in response to AMH several of these elements undergo important changes. In addition, differential expression of RAS mRNA, miRNA and protein, indicate post-transcriptional regulatory mechanisms involved with hypoxic stress, and necessitate further investigation.

T6.4 Plasma 25-hydroxyvitamin D in early-onset severe preeclampsia

The stress of Antenatal Maternal Hypoxia (AMH) can lead to a number of physiological and pathological changes in both mother and fetus, changes which can be linked to alterations in placental morphology and gene regulation. Recently, in the Brown Norway rat “model” of placental insufficiency, we reported alterations in placental renin-angiotensin system (RAS) genes. Moreover, AMH can lead to reduced oxygen availability to the fetus, similar to a state of placental insufficiency. Thus, in pregnant mice dams we tested the hypothesis that antenatal maternal hypoxic stress leads to alterations in the placental RAS. These alterations may, in part, account for the phenotypic changes in both pregnant mice dams as well as fetus and adult offspring.Pregnant FVB/NJ mice dams were either maintained as controls, or exposed to 10.5% O2 for 48 h from 15.5 to 17.5 day post coitum. We then measured placental mRNA and protein expression of several RAS genes (n = 4 to 5; P < 0.05 was considered significant).In murine placenta: (1) angiotensinogen (AGT) mRNA was undetectable; however, AGT protein was detectable and increased significantly with AMH. (2) In AMH, although renin mRNA was reduced protein expression increased, in association with decreased microRNA (miRNA) 199b, which can lead to increased renin translation. (3) Also in AMH placenta, angiotensin converting enzyme (ACE) -1 mRNA was unaltered; however, protein expression increased significantly, in association with decreased miRNA 27a, which can result in increased ACE-1 translation. (4) In AMH placenta, ACE-2 mRNA was reduced significantly, whereas protein expression was significantly greater, in association with reduced miRNA 429. (5) In AMH placenta, angiotensin II type (AT) -1a receptor mRNA expression was unaltered while AT-1b receptor mRNA was undetectable in both groups. Moreover, AT-1 receptor protein expression was unchanged in response to AMH. (6) AT-2 receptor mRNA and proteins were undetectable in both groups.The normal murine placenta possesses several components of RAS, and in response to AMH several of these elements undergo important changes. In addition, differential expression of RAS mRNA, miRNA and protein, indicate post-transcriptional regulatory mechanisms involved with hypoxic stress, and necessitate further investigation.

The renin-angiotensin system and hypertension in autosomal recessive polycystic kidney disease

Hypertension is a well-recognized complication of autosomal recessive polycystic kidney disease (ARPKD). The renin-angiotensin system (RAS) is a key regulator of blood pressure; however, data on the RAS in ARPKD are limited and conflicting, showing both up- and down-regulation. In the current study, we characterized intrarenal and systemic RAS activation in relationship to hypertension and progressive cystic kidney disease in the ARPKD orthologous polycystic kidney (PCK) rat. Clinical and histological measures of kidney disease, kidney RAS gene expression by quantitative real-time PCR, angiotensin II (Ang II) immunohistochemistry, and systemic Ang I and II levels were assessed in 2-, 4-, and 6-month-old cystic PCK and age-matched normal rats. PCK rats developed hypertension and progressive cystic kidney disease without significant worsening of renal function or relative kidney size. Intrarenal renin, ACE and Ang II expression was increased significantly in cystic kidneys; angiotensinogen and Ang II Type I receptor were unchanged. Systemic Ang I and II levels did not differ. This study demonstrates that intrarenal, but not systemic, RAS activation is a prominent feature of ARPKD. These findings help reconcile previous conflicting reports and suggest that intrarenal renin and ACE gene upregulation may represent a novel mechanism for hypertension development or exacerbation in ARPKD.

Brain Renin-Angiotensin System: Fetal Epigenetic Programming by Maternal Protein Restriction During Pregnancy

Maternal protein malnutrition during pregnancy can lead to significant alterations in the systemic renin-angiotensin system (RAS) in the fetus. All components of the RAS are present in brain and may be altered in many disease states. Importantly, these disorders are reported to be of higher incidence in prenatally malnourished individuals. In the current study, we tested the hypothesis that antenatal maternal low protein diet (MLPD) leads to epigenetic changes and alterations in gene expression of brain RAS of the mouse fetus. Mice dams were given control and 50% MLPD during second half of the gestation. We analyzed messenger RNA (mRNA), microRNA (miRNA), promoter DNA methylation, and protein expression of various RAS genes in the fetal offspring. As a consequence of 50% MLPD, fetal brains showed increased mRNA expression of angiotensinogen and angiotensin converting enzyme-1 (ACE-1), with a decrease in mRNA levels of angiotensin II type-2 (AT2) receptors. In contrast, while angiotensinogen protein expression was unaltered, the protein levels of ACE-1 and AT2 receptor genes were significantly reduced in the fetal brain from the MLPD dams. Our results also demonstrated hypomethylation of the CpG islands in the promoter regions of ACE-1 gene, and upregulation of the miRNAs, mmu-mir-27a and 27b, which regulate ACE-1 mRNA translation. Furthermore, our study showed reduced expression of the miRNA mmu-mir-330, which putatively regulates AT2 translation. For the developing fetal brain RAS, MLPD leads to significant alterations in the mRNA and protein expression, with changes in DNA methylation and miRNA, key regulators of hypertension in adults.

Hemodynamic, Morphometric and Autonomic Patterns in Hypertensive Rats - Renin-Angiotensin System Modulation

BACKGROUND:Spontaneously hypertensive rats develop left ventricular hypertrophy, increased blood pressure and blood pressure variability, which are important determinants of heart damage, like the activation of renin-angiotensin system.AIMS:To investigate the effects of the time-course of hypertension over 1) hemodynamic and autonomic patterns (blood pressure; blood pressure variability; heart rate); 2) left ventricular hypertrophy; and 3) local and systemic Renin-angiotensin system of the spontaneously hypertensive rats.METHODS:Male spontaneously hypertensive rats were randomized into two groups: young (n=13) and adult (n=12). Hemodynamic signals (blood pressure, heart rate), blood pressure variability (BPV) and spectral analysis of the autonomic components of blood pressure were analyzed. LEFT ventricular hypertrophy was measured by the ratio of LV mass to body weight (mg/g), by myocyte diameter (μm) and by relative fibrosis area (RFA, %). ACE and ACE2 activities were measured by fluorometry (UF/min), and plasma renin activity (PRA) was assessed by a radioimmunoassay (ng/mL/h). Cardiac gene expressions of Agt, Ace and Ace2 were quantified by RT-PCR (AU).RESULTS:The time-course of hypertension in spontaneously hypertensive rats increased BPV and reduced the alpha index in adult spontaneously hypertensive rats. Adult rats showed increases in left ventricular hypertrophy and in RFA. Compared to young spontaneously hypertensive rats, adult spontaneously hypertensive rats had lower cardiac ACE and ACE2 activities, and high levels of PRA. No change was observed in gene expression of Renin-angiotensin system components.CONCLUSIONS:The observed autonomic dysfunction and modulation of Renin-angiotensin system activity are contributing factors to end-organ damage in hypertension and could be interacting. Our findings suggest that the management of hypertensive disease must start before blood pressure reaches the highest stable levels and the consequent established end-organ damage is reached.

Losartan, an Angiotensin Type I Receptor, Restores Erectile Function by Downregulation of Cavernous Renin-Angiotensin System in Streptozocin-Induced Diabetic Rats

The high incidence of erectile dysfunction (ED) in diabetes highlights the need for good treatment strategies. Recent evidence indicates that blockade of the angiotensin type I receptor (AT1) may reverse ED from various diseases. To explore the role of cavernous renin-angiotensin system (RAS) in the pathogenesis of diabetic ED and the role of losartan in the treatment of diabetic ED. The AT1 blocker (ARB) losartan (30 mg/kg/d) was administered to rats with streptozocin (65 mg/kg)-induced diabetes. Erectile function, cavernous structure, and tissue gene and protein expression of RAS in the corpora cavernosa were studied. We sought to determine the changes of cavernous RAS in the condition of diabetes and after treatment with losartan. RAS components (angiotensinogen, [pro]renin receptor, angiotensin-converting enzyme [ACE], and AT1) were expressed in cavernosal tissue. In diabetic rats, RAS components were upregulated, resulting in the increased concentration of angiotensin II (Ang II) in the corpora. A positive feedback loop for Ang II formation in cavernosum was also identified, which could contribute to overactivity of cavernous RAS in diabetic rats. Administration of losartan blocked the effect of Ang II, downregulated the expression of AT1 and Ang II generated locally, and partially restored erectile function (losartan-treated group revealed an improved intracavernous pressure/mean systemic arterial pressure ratio as compared with the diabetic group (0.480 +/- 0.031 vs. 0.329 +/- 0.020, P < 0.01). However, losartan could not elevate the reduced smooth muscle/collagen ratio in diabetic rats. The cavernous RAS plays a role in modulating erectile function in corpora cavernosa and is involved in the pathogenesis of diabetic ED. ARB can restore diabetic ED through downregulating cavernous RAS.

P034 Bone marrow renin-angiotensin system expression in polycythaemia vera and essential thrombocythaemia depends on JAK2 mutational status

Discovery of V617F mutation in JAK2 tyrosine kinase gene in myeloid progenitors provided new insight into the pathogenesis and clinical understanding of CMPD. There are several lines of evidence suggesting the existence of local hematopoietic bone marrow renin-angiotensin system (RAS) which contributes to the regulation of normal and disturbed hematopoiesis. Recently, it was shown that Jak2 kinase is important upstream component in the regulation of the AGT mRNA transcription: activated Jak2 kinase stimulates AGT gene transcription. These observations suggest possibility for constitutively active, mutated Jak2 to modulate transcriptional activation of AGT gene as well as the expression of other RAS genes in CMPD. Aim: We analyzed the expression of RAS genes (ACE, AGT, AT2R1 and REN) in normal BM and that of PV and ET patients with the respect to the presence of activating V617F JAK2 mutation. Patients and methods: Fourteen PV-JAK2V617Fpos patients (7 male, 7 female, median age 68), thirteen ET-JAKV617Fpos patients (6 male, 7 female, median age 72) and seven ETJAK2V617Fneg patients (3 male, 4 female, median age 66) were included in the study. Samples of normal bone marrow were obtained from fi ve healthy donors. Real-time PCR analysis for ACE, AGT, AT1R1, REN genes and internal housekeeping gene GAPDH was performed using Real Time PCR System. To compensate for inter-PCR variations, normalisation of target genes (ACE, AGT, AT2R1, REN) with an endogenous control (GAPDH) was performed. JAK2 V617F mutational status was determined by the allele-specifi c PCR. Results: ACE expression in BM of PV and ET patients was down-regulated to 2-20% of the donor BM values with no statistically signifi cant difference in expression between patients. AGT expression was signifi cantly higher in PV and in ETJAK2V617Fpos comparing to ET JAK2V617Fneg patients. Renin has shown similar pattern of expression as AGT: it was signifi cantly higher in PV and in ET JAK2V617Fpos patients comparing to ET JAK2V617Fneg patients. AT1R gene was signifi cantly higher expressed in PV patients in comparison to both ET subgroups, JAK2V617F positive or negative patients. ET patients did not differ for AT2R1 expression by their JAK2 mutational status. Conclusion: Our fi ndings indicate up-regulation of AGT, AT2R1 and REN genes and down-regulation of ACE gene expression in clonal hematopoiesis of PV and ET. Different expression pattern of major RAS components in BM of PV and ET compared to normal BM is clearly related to the existence of JAK2V617F mutation and less to the PV or ET disease phenotype. However, interesting exception is excessive expression of AT2R1 in PV that was not observed in ET irrespective of JAK2 mutation. This latest observation provides ground for the future experimental and clinical studies for the use of AT2R1 blockers in improving clinical management of JAK2V617Fpos PV.

Sucrose overload during pregnancy and lactation influences blood pressure, body weight, and renin angiotensin system gene expression in adult offspring.

Sucrose overload during pregnancy and lactation influences blood pressure, body weight, and renin angiotensin system gene expression in adult offspring.

Prenatal exposure to interleukin‐6 results in hypertension and alterations in the renin–angiotensin system of the rat

Cytokines are emerging as important in developmental processes. They may induce alterations in normal gene expression patterns, activate angiotensinogen transcription, or alter expression of the renin-angiotensin system (RAS). To determine whether prenatal exposure to interleukin-6 (IL-6) influences gene expression of the intrarenal RAS and contributes to renal dysfunction and hypertension in adulthood, we exposed female rats to IL-6 early (EIL-6 females) and late (LIL-6 females) in pregnancy and analysed blood pressure in the offspring at 5-20 weeks of age. Renal fluid and electrolyte excretion was assessed in clearance experiments, mRNA expression by real-time PCR, and protein levels by Western blot. Systolic pressure was increased at 5 weeks in IL-6 females and at 11 weeks in males. Circulatory RAS levels were increased in all IL-6 females, but angiotensin-1-converting enzyme (ACE) activity was increased only in LIL-6 females. LIL-6 males and IL-6 females showed decreased urinary flow rate and urinary sodium and potassium excretion. Dopamine excretion was decreased IL-6 females. In adult renal cortex, renin expression was increased in all IL-6 females, but angiotensinogen mRNA was increased only in LIL-6 females; AT(1) receptor (AT(1)-R) mRNA and protein levels were increased in LIL-6 females, whereas AT(2) receptor (AT(2)-R) levels were decreased in LIL-6 females and EIL-6 males. In adult renal medulla, AT(1)-R protein levels were increased in LIL-6 females, and AT(2)-R mRNA and protein levels were decreased in EIL-6 males and LIL-6 females. Prenatal IL-6 exposure may cause hypertension by altering the renal and circulatory RAS and renal fluid and electrolyte excretion, especially in females.

Tissue Gene Expression of Renin-Angiotensin System in Human Type 2 Diabetic Nephropathy

Recent studies have proved that blockade of the renin-angiotensin system (RAS) retards the progression of diabetic nephropathy, whereas hyporeninemia is known as a typical state in diabetic subjects. The purpose of this study is to determine whether expression levels of RAS differ between nondiabetic and diabetic renal tissues with accurate quantitative method. Subjects were 66 nondiabetic and 8 diabetic patients with biopsy-proven renal diseases. The eight diabetic subjects suffered from type 2 diabetes with overt proteinuria. Renal histology revealed typical diffuse or nodular lesions with linear IgG deposit on immunofluorescent staining and thickened basement membrane on electronic microscopy. Total RNA from a small part of the renal cortical biopsy specimens was reverse-transcribed, and the resultant cDNA was amplified for new major components of RAS (i.e., renin, renin receptor, angiotensinogen, ACE, ACE2, angiotensin II type 1 receptor, and angiotensin II type 2 receptor) and measured. Among these components, a significant upregulation was observed in the ACE gene in diabetic renal tissue. The results suggest that renal tissue RAS might be activated in the respect that ACE gene expression is upregulated in spite of a tendency to low renin expression in type 2 diabetic nephropathy.

Altered renin–angiotensin system gene expression causes renal hypoplasia in the rats with nitrofen-induced diaphragmatic hernia

The association between renal hypoplasia and pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) has become recently appreciated. However, the underlying mechanisms responsible for this association are still unknown. Renin-angiotensin system (RAS) plays an important role in renal and somatic growth, angiogenesis and reproduction. We hypothesized that abnormal expression of RAS components may be responsible for renal hypoplasia in CDH. We therefore designed this study to examine the gene expression of main components of RAS in the kidney of nitrofen-induced CDH in the rat. Pregnant rats were exposed to either olive oil or 100 mg of nitrofen on day 9.5 of gestation. Foetuses were recovered at term and divided into three groups: control (n=8), nitrofen without CDH (n=8) and CDH (n=8). Reverse transcription polymerase chain reaction was performed to evaluate the relative amount of angiotensinogen (AGT), angiotensin II type 1 receptor with 1a and 1b subtypes (AT(1a)R and AT(1b)R), angiotensin II type 2 receptor (AT(2)R), angiotensin-converting enzyme (ACE) and renin expression in the kidney. AT(1a)R, AT(1b)R, AT(2)R, AGT and renin levels were significantly decreased in the kidney of CDH rats compared with controls. We did not find a significant difference in ACE between CDH animals and controls. Our data show that the downregulation of RAS may play an important role in the pathogenesis of renal hypoplasia in the nitrofen-induced CDH.

Precocious activation of genes of the renin-angiotensin system and the fibrogenic cascade in IgA glomerulonephritis

The renin-angiotensin system (RAS) seems to play a pivotal role in progression of immunoglobulin A (IgA) nephropathy (IgAN). Accordingly, in patients with IgAN a relationship between the RAS and the fibrogenic cascade triggered by transforming growth factor-beta1 (TGF-beta1) should be observed. This study was carried out to obtain deeper insight into the regulation of RAS and the interaction with TGF-beta1 in the diseased kidney. Twenty renal biopsies from IgAN patients and five from renal cancer patients (controls) were analyzed in both microdissected glomerular and tubulointerstitial compartments by reverse transcription-polymerase chain reaction (RT-PCR). All patients had normal renal function. The expression of the following genes was determined: angiotensinogen (Agtg), renin, angiotensin-converting enzyme (ACE), angiotensin II (Ang II) type 1 and type II (AT1 and AT2 receptors), TGF-beta1, collagen IV (Coll IV), alpha-smooth muscle actin (alpha-SMA). Quantitative data were confirmed for TGF-beta1 and ACE genes by real-time PCR. Results. RAS genes were overexpressed in IgAN patients vs. control subjects. There was no difference between glomerular and tubulointerstitial RAS gene expression levels. On the contrary, the overactivation of fibrogenic cascade genes (TGF-beta1, Coll IV, alpha-SMA) in the tubulointerstitium was observed (TGF-beta1, glomerular 0.14 +/- 0.10 SD; tubulointerstial 0.34 +/- 0.20; P = 0.000) (alpha-SMA, glomerular 0.08 +/- 0.07; tubulointerstitial 0.35 +/- 0.19; P = 0.000) (Coll IV, glomerular 0.12 +/- 0.11; tubulointerstitial 0.22 +/- 0.10; P = 0.03). This fibrogenic cascade seems to be triggered by RAS as indicated by statistically significant correlations between the expression of their respective genes. A direct relationship between the putative Ang II activity and the expression of AT receptor genes was found in the tubulointerstitium, whereas in the glomeruli this relationship was negative. In the interstitium, statistically significant positive relationships emerged between interstitial infiltrates and the gene expression of Agtg, AT1 receptor, Coll IV, and TGF-beta1. This study demonstrates that a tight regulation of the intrarenal RAS exists in IgAN and that it follows the general rules disclosed in animal models. Moreover, the RAS seems to be activated early in the diseased kidney and it appears that such activation drives inflammation and a parallel stimulation of the TGF-beta fibrogenic loop, particularly at the tubulointerstitial level.

Discoordinate re-expression of cardiac fetal genes in N(omega)-nitro-L-arginine methyl ester (L-NAME) hypertension.

Hypertension produced by chronic inhibition of nitric oxide (NO) synthase by N(omega)-nitro-L-arginine methyl ester (L-NAME) was used to determine the effect of severe pressure overload with or without left ventricular (LV) hypertrophy on the transcriptional activation of the cardiac fetal genes encoding for the natriuretic peptides (NP) atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP), and for beta-myosin heavy chain (MHC) in both atrial and ventricular muscle. A previously reported association of LV hypertrophy with the activation of cardiac renin and angiotensin-converting enzyme (ACE) in this hypertension model was also investigated. Male Sprague-Dawley rats received L-NAME (75 mg/kg/day) or were left untreated for 4 (n=12) or 8 (n=12) weeks. L-NAME-treated rats became severely hypertensive in both treatment groups but only five out of 12 8-week treatment animals showed a significantly increased LV weight to body weight (BW) ratio (LVW/BW). LV ANF mRNA, but not LV BNP mRNA, correlated significantly with LVW/BW only in animals showing LV hypertrophy. No changes were observed in atrial gene expression or plasma concentration of ANF or BNP. A significant correlation was found between LVW/BW and LV renin mRNA and LV ACE activity in rats with LV hypertrophy. LV beta-MHC mRNA levels were significantly increased in the LV of rats with or without LV hypertrophy at both 4 and 8 weeks of treatment. It is concluded that pressure overload per se does not promote NP or cardiac renin-angiotensin system gene expression while increased beta-MHC expression is a marker of LV pressure overload even in the absence of LV hypertrophy. It is apparent that L-NAME causes a disruption in the coordinated transcriptional activation of cardiac fetal genes expected of hypertrophic stimuli acting on the LV.

Left Ventricular Reverse Remodeling After Surgical Therapy for Aortic Stenosis: Correlation to Renin-Angiotensin System Gene Expression

Surgical therapy for aortic stenosis leads to reverse remodeling, with normalization of left ventricular hypertrophy (LVH). The aim of this study was to examine Renin-Angiotensin system (RAS) gene expression in this setting. Growing sheep (n=44) underwent supracoronary aortic banding for controlled induction of LVH at the age of 6 to 8 months (A=baseline). Surgical revision to completely release the pressure gradient was performed 8.3+/-1 months later (B). The animals were sacrificed after another 10.1+/-2 months (C). Along with hemodynamic measurements, subtractive hybridization and competitive polymerase chain reaction were applied to quantify mRNA expression for angiotensin-converting enzyme (ACE) and angiotensin receptors 1 and 2 (AT1-R and AT2-R). Left ventricular mass index was 82+/-21 g (A), 150+/-33 g (B), and 78+/-18 g (C), P<0.01. Left ventricular function and cardiac index remained stable. Myocardial fiber diameter was 11.3+/-0.8 (A), 15.9+/-1.2 (B), and 11.4+/-1 (C) microm, P<0.01. Gene expression was as follows: ACE 0.8+/-0.05 (A), 1.3+/-0.08 (B), and 0.9+/-0.06 (C), P<0.01; AT1-R 0.7+/-0.06 (A), 0.9+/-0.07 (B), and 0.3+/-0.04 (C), P<0.01; AT2-R 0.5+/-0.05 (A), 0.2+/-0.04 (B), and 0.5+/-0.05 (C), P<0.01. LVH in aortic stenosis coincides with significant alterations of the RAS. Surgical therapy leads to reverse remodeling, which is paralleled by regression of RAS gene expression.

Hormonal regulation of the human adipose-tissue renin–angiotensin system: relationship to obesity and hypertension

Adipose tissue secretes vasoactive substances which may contribute to the development of obesity-related hypertension. The aim of this work was to study the expression of renin-angiotensin system genes in adipose tissue of obese hypertensive subjects and the hormonal regulation of these genes. Differential expression of renin-angiotensin system genes in subcutaneous abdominal adipocytes of 12 lean normotensive, eight obese normotensive, and 10 obese hypertensive women was determined in a cross-sectional study. In vitro hormonal regulation of these genes was studied in primary human adipocytes obtained by breast reduction from healthy women. In the clinical study, 24-h ambulatory blood pressure measurement and anthropometry were used to characterize the volunteers, and adipocytes were obtained by subcutaneous needle biopsy. The in vitro regulation of renin-angiotensin system genes by hydrocortisone, insulin, thyroxin, estradiol and angiotensin II on primary cultured human mammary adipocytes was studied by quantitative reverse transcriptase polymerase chain reaction (RT-PCR). While expression of the angiotensinogen gene was significantly lower in adipocytes from both obese groups, the renin, angiotensin-converting enzyme and angiotensin II type 1 receptor genes were significantly upregulated in obese hypertensives. Hydrocortisone increased angiotensin II type 1 receptor gene and protein expression in a time- and dose-dependent manner in human adipocytes, but had no significant influence on other renin-angiotensin system genes. Expression of these genes was not significantly affected by any of the other tested hormones. Renin-angiotensin system genes are differentially regulated in human obesity and hypertension. The role of the adipose-tissue renin-angiotensin system in the development of obesity-associated hypertension or metabolic disease clearly warrants further study.