Prorenin Concentrations Research Articles

Increasing angiotensin-converting enzyme concentrations and absent angiotensin-converting enzyme activity are associated with adverse kidney outcomes in pediatric septic shock

BackgroundSepsis-induced endothelial dysfunction is proposed to cause angiotensin-converting enzyme (ACE) dysfunction and renin–angiotensin–aldosterone system (RAAS) derangement, exacerbating vasodilatory shock and acute kidney injury (AKI). Few studies test this hypothesis directly, including none in children. We measured serum ACE concentrations and activity, and assessed their association with adverse kidney outcomes in pediatric septic shock.MethodsA pilot study of 72 subjects aged 1 week–18 years from an existing multicenter, observational study. Serum ACE concentrations and activity were measured on Day 1; renin + prorenin concentrations were available from a previous study. The associations between individual RAAS components and a composite outcome (Day 1–7 severe persistent AKI, kidney replacement therapy use, or mortality) were assessed.Results50/72 subjects (69%) had undetectable ACE activity (< 2.41 U/L) on Day 1 and 27/72 (38%) developed the composite outcome. Subjects with undetectable ACE activity had higher Day 1 renin + prorenin compared to those with activity (4533 vs. 2227 pg/ml, p = 0.017); ACE concentrations were no different between groups. Children with the composite outcome more commonly had undetectable ACE activity (85% vs. 65%, p = 0.025), and had higher Day 1 renin + prorenin (16,774 pg/ml vs. 3037 pg/ml, p < 0.001) and ACE concentrations (149 vs. 96 pg/ml, p = 0.019). On multivariable regression, increasing ACE concentrations (aOR 1.01, 95%CI 1.002–1.03, p = 0.015) and undetectable ACE activity (aOR 6.6, 95%CI 1.2–36.1, p = 0.031) retained associations with the composite outcome.ConclusionsACE activity is diminished in pediatric septic shock, appears uncoupled from ACE concentrations, and is associated with adverse kidney outcomes. Further study is needed to validate these findings in larger cohorts.

Circulating maternal prorenin and oocyte and preimplantation embryo development: the Rotterdam Periconception Cohort.

Could circulating maternal prorenin serve as a proxy for oocyte and preimplantation embryo development, assessed by time-lapse parameters and clinical treatment outcomes? High circulating maternal prorenin concentrations after ovarian stimulation associate with a larger oocyte area, faster cleavage divisions from the five-cell stage onwards and increased chance of successful implantation. After ovarian stimulation, circulating prorenin (renin's precursor), is largely ovary-derived. Prorenin may contribute to ovarian angiotensin synthesis, which is relevant in reproduction given its role in follicular development and oocyte maturation. Prospective observational cohort study including couples requiring fertility treatment from May 2017 as a subcohort of the ongoing Rotterdam Periconception Cohort conducted in a tertiary referral hospital. Between May 2017 and July 2020, 309 couples with an indication for IVF treatment or ICSI were included. Resulting embryos (n = 1024) were submitted to time-lapse embryo culture. Time of fertilization (t0), pronuclear appearance (tPNa), and fading (tPNf) as well as the exact timing of reaching the two- to eight-cell stage (t2-t8), the start of blastulation (tSB), reaching the full (tB), and expanded blastocyst (tEB) were retrospectively recorded. Oocyte area was measured at t0, tPNa, and tPNf. Prorenin was determined at the day of embryo transfer. After adjustment for patient- and treatment-related factors, linear mixed modeling showed that higher prorenin concentrations associate with a larger oocyte area at tPNa (β 64.45 µm2, 95% CI 3.26; 125.64, P = 0.04), and faster progression from five-cell stage onwards (e.g. β8-cell -1.37 h, 95% CI -2.48; -0.26, P = 0.02). Prorenin associated positively with pre-transfer outcomes (e.g. βfertilized oocytes 2.09, 95% CI 1.43; 2.75, P < 0.001) and implantation (odds ratio+β-hCG-test: 1.79, 95% CI 1.06; 3.08, P = 0.03), but not with live birth. This prospective observational study provides associations and therefore residual confounding cannot be excluded and causality has to be shown in intervention studies. Theca cell-derived factors, such as prorenin, may help to clarify the underlying endocrine mechanism of oocyte maturation and embryo development, with a special focus on the (patho)physiological reproductive role of prorenin and the identification of factors influencing its secretion and activity, which is of great added value for improving embryo selection and predicting implantation and pregnancy outcomes. This will bring us to investigate which determinants of oocyte quality and embryo development should take center stage in developing preconception care strategies. This research was funded by the Department of Obstetrics and Gynecology of the Erasmus MC, University Medical Center, Rotterdam, the Netherlands, and the Erasmus MC Medical Research Advisor Committee's 'Health Care Efficiency Research' program (OZBS72.16080). The authors have no competing interests to disclose. N/A.

Plasma and serum prorenin concentrations in diabetes, hypertension, and renal disease.

Although the renin-angiotensin-aldosterone system plays a crucial role in fluid homeostasis and cardiovascular disease pathophysiology, measurements of plasma prorenin levels are still unavailable in clinical practice. We previously found that prorenin molecules in human blood underwent significant posttranslational modifications and were undetectable using immunological assays that utilized antibodies specifically recognizing unmodified recombinant prorenin. Using a sandwich enzyme-linked immunosorbent assay that captures posttranslationally modified prorenins with their prosegment antibodies, we measured plasma and serum prorenin concentrations in 219 patients with diabetes mellitus, hypertension and/or renal disease and compared them with those of 40 healthy controls. The measured values were not significantly different from those of the healthy controls and were 1,000- to 100,000-fold higher than previously reported levels determined using conventional assay kits. Multiple regression analyses showed that body weight, serum albumin levels, and serum creatinine levels negatively correlated with plasma prorenin levels, while the use of loop diuretics was associated with elevated plasma prorenin levels. Blood pressure, HbA1c, and plasma renin activity were not independent variables affecting plasma prorenin levels. In contrast, serum prorenin levels were unaffected by any of the above clinical parameters. The association of the plasma prorenin concentration with indices reflecting body fluid status suggests the need to scrutinize its role as a biomarker, while serum prorenins are less likely to have immediate diagnostic value.

Corpus luteum number and the maternal renin-angiotensin-aldosterone system as determinants of utero-placental (vascular) development: the Rotterdam Periconceptional Cohort

BackgroundPregnancies with > 1 corpus luteum (CL) display a hyperdynamic circulation and an increased risk of small-for-gestational age deliveries. Among the factors released by the CL is prorenin, the inactive precursor of renin. Since the renin-angiotensin-aldosterone system (RAAS) is involved in early hemodynamic pregnancy adaptation, we linked both CL number and first-trimester concentrations of prorenin (as an indicator of RAAS activity) and the aldosterone/renin ratio (as an indicator of angiotensin-independent aldosterone effectiveness) to non-invasive markers of utero-placental (vascular) development, measured longitudinally from the first trimester onwards.MethodsA total of 201 women, who conceived naturally or after in-vitro fertilization treatment (with 0 (n = 8), 1 (n = 143), or > 1 (n = 51) CL), were selected from the Rotterdam Periconceptional Cohort. Maternal RAAS components were determined at 11 weeks gestation. Placental volume and utero-placental vascular volume were measured from transvaginal 3D ultrasound scans at 7, 9 and 11 weeks gestation, pulsatility and resistance indices of the uterine arteries were assessed by pulsed wave Doppler ultrasounds at 7, 9, 11, 13, 22 and 32 weeks gestation. At birth placental weight was obtained using standardized procedures.ResultsPregnancies without a CL show lower uterine artery indices throughout gestation than 1 CL and > 1 CL pregnancies, while parameters of placental development are comparable among the CL groups. After adjustment for patient- and treatment-related factors, first-trimester prorenin concentrations are positively associated with uterine artery pulsatility and resistance indices (β 0.06, 95% CI 0.01;0.12, p = 0.04 and β 0.10, 95% CI 0.01;0.20, p = 0.04, respectively), while high prorenin concentrations are negatively associated with first-trimester utero-placental vascular volume (β -0.23, 95% CI -0.44;-0.02, p = 0.04) and placental weight (β -93.8, 95%CI -160.3;-27.4, p = 0.006). In contrast, the aldosterone/renin ratio is positively associated with first-trimester placental volume (β 0.12, 95% CI 0.01;0.24, p = 0.04).ConclusionsThe absence of a CL, resulting in low prorenin concentrations, associates with low uterine artery pulsatility and resistance, while high prorenin concentrations associate with a low utero-placental vascular volume and weight. These data support a scenario in which excess prorenin, by upregulating angiotensin II, increases uterine resistance, thereby preventing normal placental (vascular) development, and increasing the risk of small-for-gestational age deliveries. Simultaneously, high aldosterone concentrations, by ensuring volume expansion, exert the opposite.

Circulating prorenin: its molecular forms and plasma concentrations.

The renin-angiotensin-aldosterone system plays pivotal roles in the maintenance of fluid homeostasis and in the pathophysiology of major human diseases. However, the molecular forms of plasma renin/prorenin have not been fully elucidated, and measurements of plasma prorenin levels are still unavailable for clinical practice. We attempted to evaluate the molecular forms of human plasma prorenin and to directly measure its concentration without converting it to renin to determine its activity. Polyacrylamide gel electrophoresis and subsequent immunoblotting using antibodies that specifically recognise prosegment sequences were used to analyse its molecular forms in plasma. We also created a sandwich enzyme-linked immunosorbent assay suitable for directly quantifying the plasma concentration. The plasma level in healthy people was 3.0-13.4 μg/mL, which is from 3 to 4 orders of magnitude higher than the levels reported thus far. Plasma immunoreactive prorenin consists of three major distinct components: a posttranslationally modified full-length protein, an albumin-bound form and a smaller protein truncated at the common C-terminal renin/prorenin portion. In contrast to plasma renin activity, plasma prorenin concentrations were not affected by the postural changes of the donor. Hence, plasma prorenin molecules may be posttranslationally modified/processed or bound to albumin and are present in far higher concentrations than previously thought.

Prorenin independently causes hypertension and renal and cardiac fibrosis in cyp1a1-prorenin transgenic rats

Plasma prorenin is commonly elevated in diabetic patients and appears to predict the development of diabetic nephropathy. However, the pathological role of prorenin is unclear. In the present study, a transgenic, inducible, hepatic prorenin-overexpressing rat model was generated and the effect of prorenin in organ injury was examined. Four groups of rats (cyp1a1 prorenin transgenic male and female rats and non-transgenic littermates) were assigned to receive a diet containing 0.3% of the transgene inducer indole-3-carbinol (I3C) for 4 weeks. Plasma prorenin concentration was increased and mean arterial pressure (MAP) increased from 80 ± 18 to 138 ± 17 (mmHg), whereas renal prorenin/renin protein expression was unchanged, in transgenic rats fed with I3C diet. The intact prorenin, not renin, in plasma and urine samples was further observed by Western blot analysis. Importantly, transgenic rats with high levels of prorenin developed albuminuria, glomerular and tubulointerstitial fibrosis associated with increased expression of transforming growth factor β (TGFβ) 1 (TGFβ1), plasminogen activator inhibitor-1 (PAI-1), collagen, and fibronectin (FN). These rats also exhibited cardiac hypertrophy determined by echocardiography, with elevated ratio of heart weight to body weight (HW/BW). Cardiac collagen in interstitial and perivascular regions was prominent, accompanied by the increase in mRNA contents of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), β-myosin heavy chain (β-MHC), TGFβ1, PAI-1, and collagen in the heart tissue. Furthermore, renal protein levels of p-NF-κB-p65 and monocyte chemoattractant protein-1 (MCP-1), NAPDH oxidases, malondialdehyde (MDA) and 8-isoprostane (8-IP), p-ERK, p-β-catenin, and p-Akt were dramatically increased in prorenin overexpressing rats. These results indicate that prorenin, without being converted into renin, causes hypertension, renal and cardiac fibrosis via the induction of inflammation, oxidative stress and the ERK, β-catenin, and Akt-mediated signals.

ANALYSIS OF OXIDATIVE STRESS MARKERS MALONDIALDEHYDE, GLUTATHIONE, NITRIC OXIDE, AND PRORENIN LEVEL IN PREECLAMPSIA PLACENTAL TISSUES

Objective: Preeclampsia was a syndrome of hypertension proteinuria in pregnant women. In failure of pseudo vasculogenesis, there is persistency of endothelial and smooth muscle cell of vessel wall in spiral artery. Spiral artery could not be emphasis and lead to relative hypoxia, and oxidative stress in placental tissues. Endothelial cell has property to produce nitric oxide (NO) that can dilated vessel. Placenta also produces prorenin, to maintain vascular wall tonicity. Therefore, we want to uncover the property of placenta is there any capacity of prorenin, is that prorenin could overcome the NO level, or is there any depression of NO production, and any oxidative stress.Methods: This observational study was used case–control design. We search preeclampsia cases during September-December 2015. We used preeclampsia placentas from early and late onset. We collect preeclampsia placentas from Cipto Mangunkusumo and normal placentas from Budi Kemuliaan Hospital. We used 30 preeclampsia placentas and 30 normal placentas. Markers measured were NO and prorenin. NO was measured using colorimetric assay kit (K262-200/ BioVision), and prorenin was measured using human prorenin enzyme-linked immunosorbent assay kit (ab157525/ Abcam). Glutathione (GSH) was measured using Ellman method and malondialdehyde (MDA) using Wills method.Results: Prorenin concentration between normal and preeclampsia placenta was analyzed using Mann–Whitney and show that there had no significant difference between preeclampsia and normal placentas (p=0.23). Besides, NO data analyzed using independent t-test show significant differences between preeclampsia and normal placentas (p=0.001). The difference between normal and preeclampsia GSH concentration was not significant (p=0.757), besides the difference between normal and preeclampsia MDA concentration was significant (p=0.000).Conclusion: NO concentration in preeclampsia placenta was increase, higher than normal placenta. There was no effect of preeclampsia on prorenin concentration and GSH. There was marked decrease of MDA in preeclampsia placentas.

ANALYSIS OF OXIDATIVE STRESS MARKERS MALONDIALDEHYDE, GLUTATHIONE, NITRIC OXIDE, AND PRORENIN LEVEL IN PREECLAMPSIA PLACENTAL TISSUES

Objective: Preeclampsia was a syndrome of hypertension proteinuria in pregnant women. In failure of pseudo vasculogenesis, there is persistency of endothelial and smooth muscle cell of vessel wall in spiral artery. Spiral artery could not be emphasis and lead to relative hypoxia, and oxidative stress in placental tissues. Endothelial cell has property to produce nitric oxide (NO) that can dilated vessel. Placenta also produces prorenin, to maintain vascular wall tonicity. Therefore, we want to uncover the property of placenta is there any capacity of prorenin, is that prorenin could overcome the NO level, or is there any depression of NO production, and any oxidative stress.Methods: This observational study was used case–control design. We search preeclampsia cases during September-December 2015. We used preeclampsia placentas from early and late onset. We collect preeclampsia placentas from Cipto Mangunkusumo and normal placentas from Budi Kemuliaan Hospital. We used 30 preeclampsia placentas and 30 normal placentas. Markers measured were NO and prorenin. NO was measured using colorimetric assay kit (K262-200/ BioVision), and prorenin was measured using human prorenin enzyme-linked immunosorbent assay kit (ab157525/ Abcam). Glutathione (GSH) was measured using Ellman method and malondialdehyde (MDA) using Wills method.Results: Prorenin concentration between normal and preeclampsia placenta was analyzed using Mann–Whitney and show that there had no significant difference between preeclampsia and normal placentas (p=0.23). Besides, NO data analyzed using independent t-test show significant differences between preeclampsia and normal placentas (p=0.001). The difference between normal and preeclampsia GSH concentration was not significant (p=0.757), besides the difference between normal and preeclampsia MDA concentration was significant (p=0.000).Conclusion: NO concentration in preeclampsia placenta was increase, higher than normal placenta. There was no effect of preeclampsia on prorenin concentration and GSH. There was marked decrease of MDA in preeclampsia placentas.

Abstract P472: Prorenin Independently Causes Hypertension And Renal and Cardiac Fibrosis In Cyp1a1-Prorenin Transgenic Rats

Plasma prorenin is commonly elevated in diabetic patients and appears to predict the development of diabetic nephropathy. However, the pathological role of prorenin is unclear. In this study, a transgenic, inducible, hepatic prorenin-overexpressing rat model was generated and the effect of prorenin in organ injury was examined. Four groups of rats (Cyp1a1 prorenin transgenic male and female rats and nontransgenic littermates) were assigned to receive a diet containing 0.3% of the transgene inducer indole-3-carbinol (I3C) for 4 weeks. Plasma prorenin concentration rose from 23±6 to 208±44 (μg/ml) and MAP increased from 77±5 to 138±17 (mmHg), whereas renal prorenin/renin protein expression was unchanged, in transgenic rats fed with I3C diet. The intact prorenin, not renin, in plasma and urine samples was further observed by western blot analysis. Importantly, transgenic rats with high levels of prorenin developed albuminuria, glomerular and tubulointerstitial fibrosis associated with increased expression of TGFß1, PAI-1, collagen and fibronectin. These rats also exhibited cardiac hypertrophy determined by echocardiography, with elevated ratio of heart weight to body weight. Cardiac collagen in interstitial and perivascular area was prominent, accompanied by the increases in mRNA contents of ANP, BNP, ß-MHC, TGFß1 and PAI-1 in the heart tissue. Furthermore, renal protein levels of phosphor-NF-kB-p65 and MCP-1, NAPDH oxidase and MDA, phospho-ß-catenin and phospho-Akt were dramatically increased in prorenin overexpressed rats. These results indicate that prorenin, without being converted to renin, causes arterial hypertension, renal and cardiac fibrosis independently via the induction of inflammation, oxidative stress and the ß-catenin and Akt-mediated signals.

Abstract P178: Vitamin D Biomarkers with Risk of Hypertension and Renin-Angiotensin System

Background: Experimental studies suggest that vitamin D may potentially prevent the development of hypertension through down-regulation of the renin-angiotensin system. However, evidence from epidemiologic studies remains limited. Objective: In parallel nested case-control studies of women from the Women’s Health Study (WHS) and men from the Physicians’ Health Study (PHS) with &gt;10 years follow-up, we examined the prospective associations between the circulating biomarkers of vitamin D status with risk of hypertension, as well as the inter-relation between vitamin D biomarkers and renin production. Methods: In each cohort, 500 incident hypertension cases and 500 controls were randomly selected from participants who were free of cardiovascular disease, cancer, and hypertension and provided bloods at baseline. Hypertension cases were identified based on self-reported blood pressure, physician’s diagnosis, or medication use. Controls were matched to cases on gender, age, race, follow-up time, and month of blood draw. Baseline plasma 25(OH)-vitamin D, parathyroid hormone (PTH), and total renin (pro-renin plus active renin) concentrations were measured. Analyses were first performed in each cohort separately and, given the similar results, finally combined for both cohorts. Results: Baseline concentrations of 25(OH)-vitamin D (mean of 26.6 vs. 27.0 ng/mL) and PTH (32.6 vs. 32.2 pg/mL) were similar in hypertension cases and controls. In the crude matched model, the risk of hypertension did not change with 25(OH)-vitamin D or PTH concentrations. Additional adjustment for other known hypertension-related risk factors minimally affected the associations. After adjusting for baseline smoking, alcohol use, exercise, menopausal status and hormone therapy use among women, body mass index, and history of diabetes and hypercholesterolemia, the relative risks of incident hypertension across increasing quintiles of 25(OH)-vitamin D were 1.00, 1.42 (95% CI: 0.94-2.16), 0.94 (95% CI: 0.60-1.48), 0.99 (95% CI: 0.61-1.61), and 1.03 (95% CI: 0.63-1.69) (p, trend, 0.48), and across increasing quintiles of PTH were 1.00, 1.26 (95% CI: 0.83-1.92), 0.91 (95% CI: 0.60-1.40), 1.10 (95% CI: 0.70-1.71), 0.92 (95% CI: 0.59-1.44) (p, trend, 0.50). These associations were similar in men and women. Among controls, plasma 25(OH)-vitamin D was inversely correlated with PTH (Pearson r: -0.24, p&lt;0.0001), while neither 25(OH)-vitamin D (r: -0.02, p=0.53) nor PTH (r: -0.01, p=0.69) was correlated with total renin concentrations. Conclusions: In prospective cohorts of men and women, we found no association between either baseline plasma 25(OH)-vitamin D or PTH with the risk of hypertension, or between either 25(OH)-vitamin D or PTH with total renin concentration. More research is needed to further elucidate the specific effect of vitamin D in the development of hypertension.

Higher plasma prorenin concentration plays a role in the development of coronary artery disease.

BackgroundProrenin and renin are both involved in atherosclerosis. However, the role of plasma prorenin and renin in the development and progression of coronary artery disease (CAD) is still not clear. Thus, we aimed to examine the relationships among plasma prorenin concentration, CAD and clinical parameters.MethodsWe measured plasma prorenin and renin concentrations and other parameters in 85 patients who underwent coronary angiography. Patients were divided into a CAD group (≥75 % stenosis in one or more coronary arteries) and a non-CAD group.ResultsThere was a weak correlation between prorenin and plasma renin concentration (r =0.35, p =0.001), and plasma renin activity (r =0.34, p =0.001). There was no significant difference in the plasma prorenin concentration between the CAD group and non-CAD group. However, patients with a high plasma prorenin concentration frequently suffered CAD. Receiver-operating-characteristic curve analysis showed that the optimal cutoff value of plasma prorenin concentration to detect CAD was 1,100 pg/ml, with a positive predictive value of 94 % and a negative predictive value of 36 %.ConclusionThe plasma prorenin concentration increases with increases in plasma renin concentration. Higher plasma prorenin concentration (>1,100 pg/ml) plays a role in the development of CAD.

182-POS

Objectives An association between the renin-angiotensin system and the pathogenesis of pregnancy-induced hypertension has been reported. The prorenin receptor was discovered in 2002, and Wanatabe et al. reported that women with plasma soluble prorenin receptor concentrations above the 75th percentile at delivery had a significantly increased risk of preeclampsia. We evaluated plasma prorenin concentrations during pregnancy, and we assessed the incidence of pregnancy-induced hypertension. Methods We measured plasma prorenin concentrations in 430 pregnant women (565 samples). Regression analysis was performed to determine the associations between the plasma prorenin level and maternal/neonatal complications. Results The plasma prorenin concentration and gestational age had a positive correlation in non-pregnancy-induced hypertension in women with singleton pregnancies (Spearman rank-correlation coefficient, −0.215; p p p = 0.0107). Conclusions The plasma prorenin levels during pregnancy may be adversely correlated with the prorenin receptor, and low prorenin levels during late pregnancy were significantly associated with pregnancy-induced hypertension. Disclosures Y. Mikami: None. T. Narita: None. Y. Takai: None. K. Baba: None. H. Seki: None. K. Matsuoka: None.

The balance between human maternal plasma angiotensin II and angiotensin 1-7 levels in early gestation pregnancy is influenced by fetal sex

There are fetal sex-associated differences in the circulating maternal renin-angiotensin system (RAS) in early pregnancy. Plasma prorenin, angiotensin (Ang) II, Ang 1-7 and angiotensin-converting enzyme (ACE) concentrations were measured at 15 weeks' gestation in 131 women with uncomplicated pregnancies from the Adelaide SCOPE cohort. Uterine and umbilical artery Doppler sonography was performed at 20 weeks' gestation. At 15 weeks, women bearing female fetuses had higher maternal Ang II concentrations (p = 0.017) and lower Ang 1-7 to Ang II ratios (p = 0.016) than women bearing males. In women with male fetuses, Ang II positively correlated with birth weight (p = 0.028) and prorenin negatively correlated with placental weight (p = 0.014). Female fetuses had higher umbilical artery resistance indices (p = 0.019) that were related to maternal prorenin concentrations (p = 0.007). In early human pregnancy, the maternal RAS is influenced by fetal sex. The lower Ang 1-7 to Ang II ratios in women with female fetuses may contribute to the lower maternal peripheral microvascular flow as described previously and the lack of any positive effect of Ang II on fetal growth, as seen in women with male fetuses.

The effects of cyclic AMP, sex steroids and global hypomethylation on the expression of genes controlling the activity of the renin–angiotensin system in placental cell lines

The placental renin–angiotensin system (RAS) is involved in placentation. We have shown that prorenin mRNA (REN) is expressed in a first trimester trophoblast cell line (HTR-8/SVneo) but not in a choriocarcinoma cell line (BeWo). We attempted to stimulate RAS expression in these cells by cAMP, 5′-aza-2′-deoxycytidine (AZA; an inhibitor of methylation), cAMP and AZA combined, and the sex steroids medroxyprogesterone acetate (MPA) and estradiol-17β (E2) with and without cAMP. RAS mRNAs were measured by qPCR and prorenin concentration in supernatants measured by an ELISA. In HTR-8/SVneo cells, all treatments increased REN expression compared to controls and cAMP + AZA combined was more effective than either treatment alone. Prorenin levels in supernatants were similarly upregulated. In HTR-8/SVneo cells, angiotensinogen (AGT) mRNA expression was increased by MPA + E2 either with or without cAMP. AGT expression was also significantly increased by AZA. BeWo cells did not express REN or prorenin and it was not inducible with any treatment. AGT expression was significantly increased with AZA, the combination of cAMP + AZA, and MPA + E2 + cAMP treatments. Since cAMP, AZA, cAMP and AZA combined, or MPA and E2 with and without cAMP in HTR-8/SVneo cells, a cell line most similar in its RAS expression to the in vivo placenta, these factors may affect placental RAS activity. Surprisingly, these treatments also induced AGT expression in BeWo cells. Whether they are involved in regulating AGT in choriocarcinomas in vivo remains to be determined.

The Progression of Serum Prorenin Concentration during Pregnancy

Objective: An association between the renin-angiotensin system and the pathogenesis of pregnancy-induced hypertension has been reported. The prorenin receptor was discovered in 2002, and Wanatabe et al. reported that women with plasma soluble prorenin receptor concentrations above the 75th percentile at delivery had a significantly increased risk of preeclampsia. We evaluated serum prorenin concentrations during pregnancy, and we assessed the incidence of pregnancy-induced hypertension. Methods: We measured serum prorenin concentrations in 430 pregnant women (565 samples). Regression analysis was performed to determine the associations between the serum prorenin level and maternal/neonatal complications. Results: The serum prorenin concentration and gestational age had a positive correlation in non-pregnancyinduced hypertension in women with singleton pregnancies (Spearman rank-correlation coefficient, -0.215: p<0.0001). The serum prorenin concentration in women with multiple pregnancies was significantly higher than that in women with singleton pregnancies (multiple linear regression analysis, p<0.0001). Low prorenin levels in the third trimester (≤20.1 percentile) were significantly associated with pregnancy-induced hypertension (adjusted odds ratio, 18.16: 95% confidential interval, 1.95-412.41: p=0.0107). Conclusion: The serum prorenin levels during pregnancy may be adversely correlated with the prorenin receptor, and low prorenin levels during late pregnancy were significantly associated with pregnancy-induced hypertension.

Response to "Is High Prorenin Level Related to Relative Aldosterone Excess?"

To the Editor: We would like to thank Dr. Satoh and colleagues for their interest in our recent study titled “Plasma Levels of Prorenin and Renin in Black and Whites: Their Relative Abundance and Associations with Plasma Aldosterone Concentration.”1 We reported that blacks and whites had similar plasma prorenin levels, but that in blacks the plasma renin concentration (PRC) was markedly lower, and prorenin was negatively associated with plasma aldosterone concentration (PAC). In their Letter to the Editor, Dr. Satoh suggested we should further examine the association between prorenin and aldosterone to plasma renin activity ratio (aldosterone/renin ratio, or ARR), for indication that prorenin might have played a role in the relative excess of aldosterone, especially in blacks, who are thought to be more susceptible to a salt-sensitive form of hypertension. We appreciate this suggestion and agree that this is a logical and potentially important question that should be addressed in a follow-up analysis. We reexamined the data as requested. The relationships between prorenin and ARR are presented in Figure 1. Contrary to the letter’s hypothesis, we found prorenin to be negatively associated with ARR in blacks (β = –0.341; P = 0.039), and not associated with ARR in whites (β = 0.180; P = 0.301). Of note, these results essentially mirrored our previous reports on the prorenin-PAC relationships in the two race groups. Careful examination of Figure 1c and Figure 1d of the original report revealed that at any given level of PRC, prorenin was negatively associated with PAC in blacks, and positively associated with PAC in whites. The new analysis reaffirmed this observation. Figure 1. Relationship between plasma prorenin concentration and plasma aldosterone to renin activity ratio in blacks and whites. Abbreviations: PAC, plasma aldosterone concentration; PRA, plasma renin activity. We agree with Dr. Satoh and colleagues that ARR is a useful gauge for salt sensitivity, characterized by inappropriate aldosterone production and unattenuated sodium reabsorption in the presence of volume overload. Previous reports have demonstrated that ARR is higher in hypertensive blacks than in hypertensive whites.2 Our data, showing that ARR levels were marginally higher in young and normotensive blacks (Table 2 of the original paper), suggest that this difference may already be present before hypertension occurs. The new analysis, however, yielded no clear evidence for a prorenin role in aldosterone production, neither in blacks nor whites. In fact, the negative prorenin-ARR association in blacks argues against the hypothesis that prorenin promotes aldosterone production, at least in young and healthy blacks. As we have commented in the original article, this does not exclude the possibility that in some circumstances aldosterone production may become more autonomous to kidney-derived renin; when upregulated (pro)renin receptor (PRR) expression leads to a prorenin-dependent generation of angiotensin II, it is conceivable that aldosterone excess may occur with increased prorenin levels. Although the plausibility of such a hypothesis is supported by the observations that aldosterone elevation is associated with the PRR overexpression in transgenic rats and PRR gene polymorphisms in white males,3,4 the validity of the hypothesis in salt-sensitive blacks remains to be investigated.

Parallel regulation of renin and lysosomal integral membrane protein 2 in renin-producing cells: further evidence for a lysosomal nature of renin secretory vesicles

The protease renin is the key enzyme in the renin-angiotensin system (RAS) that regulates extracellular volume and blood pressure. Renin is synthesized in renal juxtaglomerular cells (JG cells) as the inactive precursor prorenin. Activation of prorenin by cleavage of the prosegment occurs in renin storage vesicles that have lysosomal properties. To characterize the renin storage vesicles more precisely, the expression and functional relevance of the major lysosomal membrane proteins lysosomal-associated membrane protein 1 (LAMP-1), LAMP-2, and lysosomal integral membrane protein 2 (LIMP-2) were determined in JG cells. Immunostaining experiments revealed strong coexpression of renin with the LIMP-2 (SCARB2), while faint staining of LAMP-1 and LAMP-2 was detected in some JG cells only. Stimulation of the renin system (ACE inhibitor, renal hypoperfusion) resulted in the recruitment of renin-producing cells in the afferent arterioles and parallel upregulation of LIMP-2, but not LAMP-1 or LAMP-2. Despite the coregulation of renin and LIMP-2, LIMP-2-deficient mice had normal renal renin mRNA levels, renal renin and prorenin contents, and plasma renin and prorenin concentrations under control conditions and in response to stimulation with a low salt diet (with or without angiotensin-converting enzyme (ACE) inhibition). No differences in the size or number of renin vesicles were detected using electron microscopy. Acute stimulation of renin release by isoproterenol exerted similar responses in both genotypes in vivo and in isolated perfused kidneys. Renin and the major lysosomal protein LIMP-2 are colocalized and coregulated in renal JG cells, further corroborating the lysosomal nature of renin storage vesicles. LIMP-2 does not appear to play an obvious role in the regulation of renin synthesis or release.

Aliskiren and perindopril reduce the levels of transforming growth factor-β in patients with non-diabetic kidney disease

It is highly likely that the rise in plasma prorenin and plasma renin during renin inhibitor treatment is induced at least as much by the fall in blood pressure (BP) as it is by the negative feedback of angiotensin II. This could potentially be harmful because high levels of renin and prorenin may stimulate the (pro)renin receptor, thus inducing profibrotic effects. To further understand this relationship, the influence of aliskiren on the urinary excretion of transforming growth factor-β1 (TGF-β1) and procollagen III N-terminal propeptide (PIIINP) was evaluated in patients with nondiabetic kidney diseases. Aliskiren 300 mg and perindopril 10 mg, were each individually administered for 12 weeks separated by a placebo period in a cross-over, randomized, double-blinded pilot study. A 1,131% (P < 0.001) and 628% (P < 0.001) increase in plasma renin concentration was observed after the aliskiren and perindopril therapies, respectively, as compared to the placebo. Aliskiren and perindopril increased prorenin concentrations as compared to the placebo by 100% (P < 0.01) and 52.4% (P = 0.53), respectively. The TGF-β1 excretion was lower after tested therapies compared to the placebo (55.0 ± 7.56 vs. 56.21 ± 8.56 vs. 85.79 ± 14.11 pg/mg creatinine; P = 0.016); without differences between aliskiren and perindopril. PIIINP excretion did not differ between treatments. The study shows that both aliskiren and perindopril suppress TGF-β1 in patients with chronic kidney diseases. This effect was observed despite significant increases in the renin and prorenin concentrations. Further studies involving histological assessments are required to elucidate the exact impact of these agents on renal fibrosis.

Regression of cardiac hypertrophy in cyp1a1ren-2 transgenic rats

To evaluate the usefulness of the cyp1a1ren-2 transgenic rat model of inducible hypertension for studies of the development and regression of cardiac hypertrophy. Cyp1a1ren-2 rats received a diet containing 0% or 0.167% indole-3-carbinonl (I3C) for 4 weeks to induce hypertension. Cardiac magnetic resonance imaging (MRI) at 7 T was performed every second week for 10 weeks to measure left ventricular mass and the ejection fraction. Concomitantly, in six cyp1a1ren-2 rats blood pressure was recorded telemetrically. Plasma prorenin concentrations rose from 138 ± 38 to 15,490 ± 3990 ng/angiotensin I/mL/h (P < 0.001) in I3C-treated transgenic rats and returned to basal levels after cessation of I3C. Mean blood pressure increased to a plateau of 169 ± 11 mmHg by the second week of induction. After cessation of I3C (day 28), arterial pressure dropped to values slightly below those prior to induction within 4 days (basal: 106 ± 7 mmHg, day 32: 103 ± 21 mmHg; NS). At day 28, left ventricular mass was increased by 39% vs. 4% in controls (P < 0.001) without changes of the ejection fraction. Cardiac hypertrophy was completely reversed at day 70, as evaluated by MRI. The cyp1a1ren-2 transgenic rat is a useful model to study reversal and healing in the absence of surgical interventions.

(Pro)renin and its receptors: pathophysiological implications

Tissue angiotensin generation depends on the uptake of circulating (kidney-derived) renin and/or its precursor prorenin [together denoted as (pro)renin]. Since tissue renin levels are usually somewhat higher than expected based upon the amount of (renin-containing) blood in tissue, an active uptake mechanism has been proposed. Several candidates have been evaluated in the past three decades, including a renin-binding protein, the mannose 6-phosphate/insulin-like growth factor II receptor and the (pro)renin receptor. Although the latter seemed the most promising, its nanomolar affinity for renin and prorenin is several orders of magnitude above their actual (picomolar) levels in blood, raising doubt on whether (pro)renin-(pro)renin receptor interaction will ever occur in vivo. A wide range of in vitro studies have now demonstrated (pro)renin-receptor-induced effects at nanomolar renin and prorenin concentrations, resulting in a profibrotic phenotype. In addition, beneficial in vivo effects of the putative (pro)renin receptor blocker HRP (handle region peptide) have been observed, particularly in diabetic animal models. Despite these encouraging results, many other studies have reported either no or even contrasting effects of HRP, and (pro)renin-receptor-knockout studies revealed lethal consequences that are (pro)renin-independent, most probably due to the fact that the (pro)renin receptor co-localizes with vacuolar H+-ATPase and possibly determines the stability of this vital enzyme. The present review summarizes all of the recent findings on the (pro)renin receptor and its blockade, and critically compares it with the other candidates that have been proposed to mediate (pro)renin uptake from blood. It ends with the conclusion that the (pro)renin-(pro)renin receptor interaction, if it occurs in vivo, is limited to (pro)renin-synthesizing organs such as the kidney.