Prorenin Levels Research Articles

Abstract 210: Urinary Renin as a New Marker of Preeclampsia?

Urinary renin-angiotensin system (RAS) components have been suggested to reflect intrarenal RAS activity. Urinary renin is elevated in diabetes, thus explaining the effectiveness of RAS blockade in diabetic nephropathy despite the low-to-normal plasma renin levels in this condition. Here we investigated urinary renin levels in preeclampsia (PE), a disease characterized by hypertension and proteinuria. We speculated that urinary renin levels might be of additional value on top of the elevated sFlt-1/PlGF ratio in PE. Renin, prorenin, creatinine (Cr), total protein, s-Flt-1 and PlGF were determined in plasma (15 PE, 6 non-PE) and/or 24 hour-urine samples (39 PE, 27 non-PE) of pregnant women. Gestational age was 33±1 in PE vs. 37±0 weeks in non-PE. The sFlt-1/PlGF ratio (523 (30-49996) vs. 10 (2.9-32.5)) (geometric mean and range) was higher in PE vs. non-PE. Plasma renin and prorenin levels in PE were 42 (range 11-181) and 190 (95-274) ng/L, versus 41 (16-80) ng/L and 129 (87-160) ng/L in non-PE. Plasma total protein levels in PE and non-PE were 50 (21-68) and 61 (58-66) g/L, resp., versus 1.0 (0.3-13) and 0.2 (0.1-1.5) g/L in urine. Plasma Cr levels in PE and non-PE were 61 (39-110) and 61 (47-83) μmol/L, resp., versus 31 (2.6-241) and 11 (3.4-56) mmol/L in urine. Urinary renin levels were ≈3 times higher in PE than in non-PE (3.2 (0.1-410) vs. 1.4 (0.3-13.0) ng/L), and 5-10 times higher than expected if filtration of plasma renin paralleled filtration of plasma protein. In contrast, urinary prorenin levels were 0.4 (0.1-84) and 0.1 (0.1-0.9) ng/L in PE and non-PE, i.e., as high as expected on the basis of plasma protein filtration. In line with these observations, urinary total protein and Cr correlated with urinary prorenin (r=0.38, P<0.05 and r=0.71, P<0.01, resp.), but not with urinary renin. In conclusion, urinary prorenin levels run in parallel with urinary total protein and Cr levels, and are as high as can be expected based upon protein filtration in the kidney. In contrast, urinary renin levels are 5-10 fold higher than expected based on filtration, and do not correlate with urinary protein or Cr. Urinary renin may therefore reflect an activation of the renal RAS in PE, and could serve as a new marker of the severity of this disease, in particular its renal consequences.

Abstract 234: Plasma Renin-Independent Generation of Angiotensin II and its Role in the Supine Hypertension of Autonomic Failure

At least 50% of primary autonomic failure [AF] patients exhibit supine hypertension, despite profound impairments in sympathetic activity. Plasma renin activity is often undetectable in AF suggesting renin mechanisms are not involved in the hypertension. However, since aldosterone levels are preserved we examined the status and contribution of the renin-angiotensin [Ang] system in AF. Supine plasma Ang peptide levels were measured in hypertensive AF patients [AF-HT, n=18], normotensive patients [AF-NT, n=11] and matched healthy subjects [n=10]. Despite suppressed renin activity, total renin concentration was intact in AF [16 ± 5 AF-HT vs 11 ± 4 AF-NT vs 7 ± 1 pg/mL healthy; p=0.29] and plasma prorenin was selectively elevated in hypertensive patients [2.0 ± 0.5 AF-HT vs 0.7 ± 0.1 AF-NT vs 0.6 ± 0.1 ng/mL healthy; p < 0.05]. While levels of Ang I were similar among groups, Ang II was paradoxically elevated [39 ± 4 AF-HT vs 42 ± 6 AF-NT vs 27 ± 4 pg/mL healthy; p<0.05] in AF. In contrast, Ang-(1-7) was suppressed in AF patients [7 ± 1 AF-HT vs 4 ± 1 AF-NT vs 22 ± 6 pg/mL healthy; p<0.05]. Plasma aldosterone was preserved in AF and did not correlate with Ang II levels, suggesting Ang II-independent regulation. The Ang II AT 1 receptor antagonist losartan [50mg, PO] significantly reduced supine systolic blood pressure [25 ± 15 mmHg at 6 hrs after administration; p<0.05] in 9 AF-HT patients, indicating that elevated Ang II contributes to hypertension in AF. These findings suggest an imbalance in Ang II and Ang-(1-7) activity in AF independent of hypertensive status, which may reflect differences in ACE and ACE2 enzyme activity. The source of Ang II in these patients, in the absence of plasma renin activity, is still under investigation. The loss of renin activity is not due to reduced renin content, but may result from low substrate availability or defective enzyme activation. Regardless, Ang II appears to contribute to the supine hypertension of AF. Further, prorenin levels are elevated in hypertensive patients which could provide a stimulus for Ang II generation and actions. Collectively, these patients offer a unique model to study cardiovascular regulation and Ang II production in the absence of autonomic and traditional renin influences.

(Pro)renin receptor is associated with angiogenic activity in proliferative diabetic retinopathy

The renin-angiotensin system (RAS) potentially has a role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor for diabetic retinopathy. We have recently shown significant involvement of (pro)renin receptor ([P]RR) in retinal inflammation in a rodent model of early diabetes. In this study we aim to elucidate the (P)RR-associated pathogenesis of fibrovascular proliferation, a late-stage angiogenic complication in human diabetic retinopathy. Vitreous fluids from 23 eyes of patients with proliferative diabetic retinopathy (PDR) and 16 eyes of controls with non-diabetic, idiopathic macular diseases (macular hole and epiretinal membrane) were collected. Protein levels of soluble (P)RR were measured by ELISA, and immunofluorescence was performed to assess the localisation of (P)RR and related molecules in fibrovascular tissues from PDR eyes. (P)RR immunoreactivity was detected in neovascular endothelial cells, colocalised with prorenin, phosphorylated extracellular signal-regulated kinase (ERK) and vascular endothelial growth factor (VEGF). Prorenin application to human retinal microvascular endothelial cells significantly upregulated mRNA expression of VEGF, especially the VEGF165 isoform, which was abolished by (P)RR or ERK signalling blockade. Proteases known to cleave (P)RR, including furin, were positive in endothelial cells in fibrovascular tissues. Protein levels of soluble (P)RR in vitreous fluids were higher in PDR eyes than in non-diabetic control eyes, and correlated significantly with vitreous prorenin and VEGF levels and the vascular density of fibrovascular tissues. Our data using human samples provide the first evidence that (P)RR is associated with angiogenic activity in PDR.

Mind–body medicine: Effect of the mind on gene expression

Abstract Purpose Positive emotions via laughter or meditation contribute to physiological and psychological health. In this review, we summarize how positive emotions affect gene expression in humans and an animal model. Study selection and results Our first studies demonstrated that mirthful laughter reduced a postprandial elevation in blood glucose levels in type II diabetes patients and increased the expression of genes related to natural killer cell activity. Furthermore, laughter decreased the plasma prorenin level, a marker for the progression of diabetic complications, and normalized the expression level of the prorenin receptor gene in peripheral blood leukocytes. These findings suggest a preventive effect of laughter on the exacerbation of diabetic conditions, which is accompanied by changes in the expression of discriminating genes. Our next study examined the effects of tactile stimulation (tickling) on socially isolated adolescent rats. Evoking positive emotions by tickling influenced neurogenesis in the dentate gyrus of the hippocampus and altered the expression of genes related to feeding regulation, blood pressure control, and biological rhythms in the corpus striatum and hypothalamus. Thus, positive emotions via tickling can regulate gene expression in the rat brain in a site-specific manner. Lastly, we review the relevant research of other groups. Meditation, a widely known healing technique, altered the expression of genes associated with cellular metabolism and oxidative stress responses, suggesting the inhibition of cell injury due to chronic stress. Conclusions Mind–body medicine potentially elicits positive emotions affecting gene expression.

Plasma Levels of Prorenin and Renin in Blacks and Whites: Their Relative Abundance and Associations With Plasma Aldosterone Concentration

All renin arises from prorenin. The proportion of renin relative to prorenin could influence overall renin-angiotensin-aldosterone activity. We sought to determine whether prorenin levels were related to extracellular volume, as reflected by the levels of plasma renin activity (PRA), and to aldosterone. We analyzed plasma levels of prorenin, renin, and aldosterone, as well as their interactions, in 129 young blacks and whites. Blacks had lower plasma renin concentration (PRC) and PRA, but had prorenin levels similar to whites (69 pg/ml in blacks vs. 62 pg/ml in whites, P = 0.41). As a result, the renin-to-total renin ratio was significantly lower in blacks (11.5% in blacks as compared to 19.8% in whites; P = 0.0001). Because prorenin also resides in tissues including the adrenal where it can bind to a specific receptor to generate angiotensin II, we examined the relationship of prorenin levels to plasma aldosterone concentrations (PAC). While a positive association between PRC and PAC was found in both blacks and whites, PAC was positively related to prorenin in whites (P = 0.04) but negatively in blacks, an observation that we hypothesize was due to reduced prorenin-to-renin conversion in blacks. We observed a disproportionately high level of prorenin in blacks. These high circulating prorenin levels however do not result in greater adrenal angiotensin II and aldosterone production in healthy young blacks.

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.

Receptor-mediated nonproteolytic activation of prorenin and induction of TGF-β1 and PAI-1 expression in renal mesangial cells

While elevated plasma prorenin levels are commonly found in diabetic patients and correlate with diabetic nephropathy, the pathological role of prorenin, if any, remains unclear. Prorenin binding to the (pro)renin receptor [(p)RR] unmasks prorenin catalytic activity. We asked whether elevated prorenin could be activated at the site of renal mesangial cells (MCs) through receptor binding without being proteolytically converted to renin. Recombinant inactive rat prorenin and a mutant prorenin that is noncleavable, i.e., cannot be activated proteolytically, are produced in 293 cells. After MCs were incubated with 10(-7) M native or mutant prorenin for 6 h, cultured supernatant acquired the ability to generate angiotensin I (ANG I) from angiotensinogen, indicating both prorenins were activated. Small interfering RNA (siRNA) against the (p)RR blocked their activation. Furthermore, either native or mutant rat prorenin at 10(-7) M alone similarly and significantly induced transforming growth factor-β(1), plasminogen activator inhibitor-1 (PAI-1), and fibronectin mRNA expression, and these effects were blocked by (p)RR siRNA, but not by the ANG II receptor antagonist, saralasin. When angiotensinogen was also added to cultured MCs with inactive native or mutant prorenin, PAI-1 and fibronectin were further increased significantly compared with prorenin or mutant prorenin alone. This effect was blocked partially by treatment with (p)RR siRNA or saralasin. We conclude that prorenin binds the (p)RR on renal MCs and is activated nonproteolytically. This activation leads to increased expression of PAI-1 and transforming growth factor-β(1) via ANG II-independent and ANG II-dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may play a role in the development of diabetic nephropathy.

Enhanced intrarenal receptor-mediated prorenin activation in chronic progressive anti-thymocyte serum nephritis rats on high salt intake

Despite suppression of the circulating renin-angiotensin system (RAS), high salt intake (HSI) aggravates kidney injury in chronic kidney disease. To elucidate the effect of HSI on intrarenal RAS, we investigated the levels of intrarenal prorenin, renin, (pro)renin receptor (PRR), receptor-mediated prorenin activation, and ANG II in chronic anti-thymocyte serum (ATS) nephritic rats on HSI. Kidney fibrosis grew more severe in the nephritic rats on HSI than normal salt intake. Despite suppression of plasma renin and ANG II, marked increases in tubular prorenin and renin proteins without concomitant rises in renin mRNA, non-proteolytically activated prorenin, and ANG II were noted in the nephritic rats on HSI. Redistribution of PRR from the cytoplasm to the apical membrane, along with elevated non-proteolytically activated prorenin and ANG II, was observed in the collecting ducts and connecting tubules in the nephritic rats on HSI. Olmesartan decreased cortical prorenin, non-proteolytically activated prorenin and ANG II, and apical membranous PRR in the collecting ducts and connecting tubules, and attenuated the renal lesions. Cell surface trafficking of PRR was enhanced by ANG II and was suppressed by olmesartan in Madin-Darby canine kidney cells. These data suggest the involvement of the ANG II-dependent increase in apical membrane PRR in the augmentation of intrarenal binding of prorenin and renin, followed by nonproteolytic activation of prorenin, enhancement of renin catalytic activity, ANG II generation, and progression of kidney fibrosis in the nephritic rat kidneys on HSI. The origin of the increased tubular prorenin and renin remains to be clarified. Further studies measuring the urinary prorenin and renin are needed.

The interaction between prorenin, renin and the (pro)renin receptor

Elevated prorenin levels are seen in diabetics with microvascular disease. The discovery of a receptor capable of binding renin and prorenin [(P)RR] and triggering an intracellular signal in the laboratory setting raised the expectation that prorenin might be directly responsible for these vascular disorders. However, there has been substantial disagreement concerning the signaling properties of renin and prorenin and it has been impossible to inactivate the (P)RR gene in mouse to define its function. Mouse and rat models in which prorenin is highly overexpressed do not demonstrate the glomerulosclerosis typically seen in severe diabetic nephropathy, but do exhibit an increase in blood pressure that is angiotensin II-dependent. (P)RR has been shown to colocalize with other subunits of the vacuolar ATPase in the kidney and heart and to be necessary for Wnt signaling in a renin-independent manner. Although whole-body inactivation of the (P)RR gene is lethal, tissue-specific inactivation results in severe disorders associated with massive cell death. These results do not support a role of direct prorenin or renin signaling through (P)RR in vascular disorders. Rather, they suggest that the main role of (P)RR is as a subunit of the vacuolarATPase complex. Whether or not (P)RR is responsible for the ability of prorenin to generate angiotensin II in tissues has not been resolved.

The Prorenin Receptor

The discovery of the prorenin receptor, now nearly a decade ago, altered our view of the renin-angiotensin system (RAS).[1][1],[2][2] Binding of prorenin, the inactive precursor of renin, to the prorenin receptor results in full catalytic activity of prorenin through a nonproteolytic mechanism that

Evaluation of a direct prorenin assay making use of a monoclonal antibody directed against residues 32–39 of the prosegment

Prorenin is an early marker of microvascular complications in diabetes. However, it can only be measured indirectly (following its conversion to renin), with a renin immunoradiometric assay (IRMA). Unfortunately, treatment with a renin inhibitor interferes with this assay, because renin inhibitors induce a conformational change in prorenin, thereby allowing its detection as renin. We evaluated Molecular Innovation's new direct prorenin ELISA, which makes use of an antibody that recognizes an epitope near prorenin's putative cleavage site (R 43 L 44), thus no longer requiring prorenin activation. Plasma samples of 41 diabetic individuals treated with aliskiren (renin inhibitor) or irbesartan were tested. Semi-purified recombinant prorenin was used as standard, because the ELISA standard yielded approximately 10-fold lower values in the renin IRMA following its conversion to renin. The ELISA detected prorenin levels that were identical to those determined by the IRMA in untreated and irbesartan-treated individuals. Yet, it yielded higher prorenin levels in aliskiren-treated individuals. Aliskiren, at levels reached in plasma during treatment, did not interfere with the ELISA, but allowed the detection of up to 20-30% of prorenin as renin in the IRMA, thereby resulting in a significant overestimation of renin and an underestimation of prorenin. The ELISA rendered results within 2 h and did not require a pretreatment period of several days to convert prorenin to renin. The new direct assay allows rapid prorenin detection, is not hampered by aliskiren when used at clinically relevant doses, and might be used to identify diabetic patients developing retinopathy and/or nephropathy.

Increased renin excretion is associated with augmented urinary angiotensin II levels in chronic angiotensin II-infused hypertensive rats

Renin expression in principal cells of collecting ducts (CD) is upregulated in angiotensin II (ANG II)-dependent hypertensive rats; however, it remains unclear whether increased CD-derived renin undergoes tubular secretion. Accordingly, urinary levels of renin (uRen), angiotensinogen (uAGT), and ANG II (uANG II) were measured in chronic ANG II-infused Sprague-Dawley rats (80 ng/min for 14 days, n = 10) and sham-operated rats (n = 10). Systolic blood pressure increased in the ANG II rats by day 5 and continued to increase throughout the study (day 13; ANG II: 175 ± 10 vs. sham: 116 ± 2 mmHg; P < 0.05). ANG II infusion increased renal cortical and medullary ANG II levels (cortical ANG II: 606 ± 72 vs. 247 ± 43 fmol/g; P < 0.05; medullary ANG II: 2,066 ± 116 vs. 646 ± 36 fmol/g; P < 0.05). Although plasma renin activity (PRA) was suppressed in the ANG II-infused rats (0.3 ± 0.2 vs. 5.5 ± 1.8 ng ANG I·ml(-1)·h(-1); P < 0.05), renin content in renal medulla was increased (12,605 ± 1,343 vs. 7,956 ± 765 ng ANG I·h(-1)·mg(-1); P < 0.05). Excretion of uAGT and uANG II increased in the ANG II rats [uAGT: 1,107 ± 106 vs. 60 ± 26 ng/day; P < 0.0001; uANG II: 3,813 ± 431 vs. 2,080 ± 361 fmol/day; P < 0.05]. By day 13, despite suppression of PRA, urinary prorenin content increased in ANG II rats [15.7 ± 3 vs. 2.6 ± 1 × 10(-3) enzyme units excreted (EUE)/day, P < 0.01] as was the excretion rate of renin (8.6 ± 2 × 10(-6) EUE/day) compared with sham (2.8 ± 1 × 10(-6) EUE/day; P < 0.05). Urinary renin and prorenin protein levels examined by Western blot were augmented ∼10-fold in the ANG II-infused rats. Concomitant AT(1) receptor blockade with candesartan prevented the increase. Thus, in ANG II-dependent hypertensive rats with marked PRA suppression, increased urinary levels of renin and prorenin reflect their augmented secretion by CD cells into the luminal fluid. The greater availability of renin and AGT in the urine reflects the capability for intratubular ANG II formation which stimulates sodium reabsorption in distal nephron segments.

Aliskiren Ameliorates Renal Inflammation and Fibrosis Induced by Unilateral Ureteral Obstruction in Mice

Renin-angiotensin system activation is involved in inflammation and fibrosis in the kidney. Aliskiren, a direct renin inhibitor, decreases renin-angiotensin system activation, including plasma renin activity and angiotensin II, but increases the prorenin level, which may promote inflammation and fibrosis in renal tissue. Thus, we evaluated whether inhibiting the renin-angiotensin system by aliskiren would decrease renal inflammation and fibrosis in a mouse model of unilateral ureteral obstruction. Ten-week-old male C57BL/6 mice (Samtako, Kyoung Gi-Do, Korea) weighing 30 to 33 gm were divided into 4 groups, including vehicle or aliskiren treated sham operated and vehicle or aliskiren treated unilateral ureteral obstruction groups. We evaluated plasma renin activity, and plasma renin and renal mRNA expression levels of renin and (pro)renin receptor. To evaluate inflammation and fibrosis renal mRNA expression of monocyte chemotactic protein-1, osteopontin and transforming growth factor-β was measured. Hematoxylin and eosin, Masson's trichrome staining, and immunohistochemical staining for CD68, transforming growth factor-β and α-smooth muscle actin were performed. Plasma renin activity was significantly lower in the aliskiren treated obstruction group than in the vehicle treated obstruction group. Aliskiren treatment increased renal mRNA expression of renin. The number of CD68 positive cells, and renal monocyte chemotactic protein-1 and osteopontin mRNA levels were significantly higher in mice with unilateral ureteral obstruction than in sham operated mice. Aliskiren decreased the increased levels of these inflammation markers. Aliskiren also decreased renal transforming growth factor-β mRNA expression, transforming growth factor-β and α-smooth muscle actin immunostaining, and Masson's trichrome stained areas of unilateral ureteral obstruction kidneys. Aliskiren has anti-inflammatory and antifibrotic effects in an experimental unilateral ureteral obstruction mouse model.

The association of plasma prorenin level with an oxidative stress marker, 8-OHdG, in nondiabetic hemodialysis patients

Circulating prorenin contributes to the pathogenesis of tissue damage leading to cardiovascular disease (CVD) in hypertension and diabetic mellitus (DM) by activating the tissue renin-angiotensin-aldosterone (RAS) system; however, little is known about its roles in hemodialysis (HD) patients. We evaluated plasma prorenin level and prorenin receptor [(P)RR] expression in peripheral blood mononuclear cells (PBMCs) in 49 nondiabetic HD (non-DM-HD) patients. Then we investigated the association between plasma prorenin level or (P)RR expression level in PBMCs and CVD-predictive biomarkers. The plasma prorenin level increased in non-DM-HD patients [147.1±118.9pg/ml (standard value <100pg/ml)]. The (P)RR mRNA expression level in PBMCs also increased 1.41±0.39-fold in non-DM-HD patients compared with that in healthy control subjects (p<0.001). Although plasma prorenin level did not correlate with plasma BNP level and plasma high-sensitivity C-reactive protein level, it significantly correlated with plasma 8-hydroxydeoxyguanosine (8-OHdG) level (r=0.535, p<0.001). The plasma prorenin level did not correlate with plasma renin activity (PRA), plasma angiotensin I (AT I) level, plasma angiotensin II (AT II) level and plasma aldosterone (Ald) level. PRA, plasma AT I level, plasma AT II level and plasma Ald level did not correlate with the level of any CVD predictive biomarker. (P)RR expression level in PBMCs did not correlate with the level of any CVD predictive biomarker. The plasma prorenin level and (P)RR expression level in PBMCs increased, and the plasma prorenin level was associated with plasma 8-OHdG level independent of circulating RAS in non-DM-HD patients.

A high concentration of prorenin in early pregnancy is associated with development of pre-eclampsia in women with type 1 diabetes

The aim of this study was to investigate whether components of the renin-angiotensin system and semicarbazide-sensitive amine oxidase (SSAO) are associated with the development of pre-eclampsia in women with type 1 diabetes. This was an observational study of 107 consecutive pregnant women with type 1 diabetes (median duration 16 years [range 1-36 years], HbA(1c) 6.6% [range 4.9-10.5%]) in early pregnancy. At 8, 14, 21, 27 and 33 weeks and once within 5 days postpartum, blood was sampled for measurements of prorenin, renin, angiotensinogen, ACE and SSAO. HbA(1c), blood pressure and urinary albumin excretion were recorded. Pre-eclampsia was defined as blood pressure >140/90 mmHg and proteinuria ≥300 mg/24 h after 20 weeks. Pre-eclampsia developed in nine women (8%) with longer diabetes duration (median 20 [range 10-32] vs 16 [range 1-36] years, p = 0.04), higher SSAO concentrations (592 [range 372-914] vs 522 [range 264-872] mU/l, p = 0.04) and a tendency towards higher prorenin levels (136 [range 50-296] vs 101 [range 21-316] ng angiotensin I ml(-1) h(-1), p = 0.06) at 8 weeks compared with women without pre-eclampsia. Levels of renin, angiotensinogen and ACE did not differ in the two groups. Throughout pregnancy, prorenin and SSAO levels were 30% (p = 0.004) and 16% (p = 0.04) higher, respectively, in women developing pre-eclampsia. Using multivariate logistic regression analysis, prorenin concentration at 8 weeks was associated with pre-eclampsia (OR 4.4 [95% CI 1.5-13.0], p = 0.007), i.e. an increase of prorenin of 100 ng angiotensin I ml(-1) h(-1) implies a 4.4 times higher risk of subsequent pre-eclampsia. In type 1 diabetic women with pre-eclampsia, a higher concentration of prorenin in early pregnancy and higher levels of prorenin and SSAO throughout pregnancy were seen.

Higher levels of prorenin predict development of diabetic retinopathy in patients with type 2 diabetes

The aim was to determine whether serum prorenin levels affect the development of diabetic retinopathy (DR) in type 2 diabetes. Baseline serum prorenin levels were measured in 196 patients (85 males, 111 females) with type 2 diabetes without DR using the antibody-activating direct prorenin assay. The fundi were checked regularly. The participants were divided into two groups based on the serum prorenin levels (high and low). We used Kaplan-Meyer analysis to detect differences in the development of DR between the two groups within the same gender. Kaplan-Meyer analysis showed that males with a high serum prorenin level tended to develop DR earlier and more frequently than males with a low prorenin level ( p = 0.004 by the log rank test). However, there was no difference in the development of DR between high and low groups in females (p = 0.58). Serum prorenin levels in males with type 2 diabetes could be a new prognostic indicator of the development of DR.

Podocytes as a Target of Prorenin in Diabetes

High plasma prorenin levels predict the onset of microvascular complications, such as albuminuria/proteinuria,in diabetic patients. In diabetic rats with elevated plasma prorenin levels, treatment with HRP, which competitively inhibits the binding of prorenin to the (pro)renin receptor [(P)RR] as a decoy peptide, significantly prevented the development of albuminuria/proteinuria and glomerulosclerosis, suggesting that (P)RR-bound prorenin plays a significant role in the pathogenesis of diabetic nephropathy. Recently, the presence of (P)RR in podocytes, which represent one of the glomerular filtration barriers, has been reported. Although podocytes are subjected to both high glucose levels and mechanical stretching caused by glomerular hyperfiltration under diabetic conditions, the expression of (P)RR is reportedly regulated by high glucose levels in in vitro mesangial cells and the in vivo kidneys of diabetic rats, whereas mechanical stretching is up-regulated by (P)RR expression in human podocytes. In addition, prorenin treatment not only leads to the generation of intracellular angiotensin (Ang)II, but also activates the phosphorylation of ERK via (P)RR in a manner that acts independently of AngII in human podocytes. Thus, the upregulation of prorenin and (P)RR in podocytes as a result of glomerular hyperfiltration might play an important role in the development of albuminuria/proteinuria via the generation of intracellular AngII and the stimulation of (P)RR-dependent intracellular signals. Further inquiry regarding podocyte (P)RR intracellular signal transduction will be needed to develop a new therapeutic approach targeting podocyte (P)RR in patients with diabetic nephropathy.

Effects of medical therapies on retinopathy progression in type 2 diabetes: Is blood pressure control the lower the better?

Effects of medical therapies on retinopathy progression in type 2 diabetes: Is blood pressure control the lower the better?

Involvement of activated prorenin in the pathogenesis of slowly progressive nephropathy in the non-clipped kidney of two kidney, one-clip hypertension

The handle region peptide (HRP), a (pro)renin receptor (P)RR blocker, did not prevent the acute nephropathy occurring 2 weeks after clipping in renovascular hypertensive rats. This study was performed to examine the effects of HRP, its scramble peptide, or a saline vehicle on slowly progressive nephropathy occurring in the kidneys of two-kidney, one-clip Goldblatt hypertensive rats. At 2 weeks after clipping, the renal morphology in the clipped and non-clipped kidneys was similar in the three groups of rats. At 12 weeks after clipping, however, the glomerulosclerosis index (GI) and the tubulointerstitial damage (TD) of the non-clipped kidneys of the HRP-treated rats were significantly lower than those of vehicle-treated rats, although the GI and the TD were similar in the rats treated with scramble peptide and vehicle. The GI and the TD of the clipped kidneys were similar in the three groups of rats at 12 weeks after clipping. In the non-clipped kidneys at 12 weeks after clipping, activated prorenin levels, angiotensin II levels and transforming growth factor (TGF)-β mRNA levels of HRP-treated rats were significantly lower than those of vehicle-treated rats, although they were similar in the non-clipped kidneys from the rats treated with scramble peptide and vehicle. In the clipped kidneys at 12 weeks after clipping, activated prorenin levels, angiotensin II levels and TGF-β mRNA levels were similar in the three groups of rats. These results suggest that the ((P)RR)-dependent activation of prorenin contributes to the pathogenesis of slowly progressive nephropathy in the intact kidney in a rat model of renovascular hypertension.

Increased dietary NaCl potentiates the effects of elevated prorenin levels on blood pressure and organ disease

Rats with several 100-fold elevation of plasma prorenin levels due to liver-specific expression of a rat prorenin transgene have cardiac and aortic hypertrophy, renal lesions, and myocardial fibrosis. The effect of increased dietary NaCl on the phenotype of prorenin transgenic rats has not been examined. We compared the effects of 0.3 and 2% dietary NaCl in wild-type and transgenic rats from 3 to 12 months of age. In comparison with wild-type rats, transgenic rats receiving 0.3% dietary NaCl had approximately 1000-fold elevation of prorenin, 1.5-fold to 2.5-fold elevation of renin concentration and activity, wild-type levels of angiotensin II, and were hypertensive with cardiac and aortic hypertrophy, and increased renal glomerular and tubulo-interstitial injury score. In wild-type rats, 2% dietary NaCl reduced angiotensin levels, produced a delayed increase in blood pressure, and caused cardiac hypertrophy and tubulo-interstitial injury. By contrast, 2% NaCl did not reduce angiotensin levels in transgenic rats, potentiated their hypertension, cardiac and aortic hypertrophy, and increased myocardial interstitial and perivascular fibrosis, without effect on glomerular or tubulo-interstitial injury score. Increased dietary NaCl had a greater impact on the phenotype of transgenic than wild-type rats that may have been due, in part, to their hypertension and their failure to suppress angiotensin levels, consequent to their elevated prorenin levels.