Abstract P198: Biphasic And Sex-dependent Roles Of The Prorenin Receptor In The Rostral Ventrolateral Nucleus In Mice Subjected To Deoxycorticosterone Acetate-salt Hypertension

The brain renin angiotensin system (RAS) regulates blood pressure (BP) and autonomic function. However, it remains unclear how and where angiotensin II (Ang II) is generated in conditions eliciting brain RAS overactivation including deoxycorticosterone acetate (DOCA)-salt hypertension (HT). In several tissues, the activation of prorenin requires its binding to the prorenin receptor (PRR). New evidence from this study indicates that prorenin and PRR are co-expressed in the proximity to the rostral ventrolateral nucleus (RVL), an anatomical brain region that controls sympathetic nerve activity. Therefore, we hypothesized that selective ablation of PRR targeting the RVL attenuates BP increase due to DOCA-salt. PRR ablation was targeted to the RVL by stereotactic microinjections of adeno-associated virus (AAV) expressing Cre recombinase-mCherry in PRR-flox mice (PRR RVL-KO ). AAV mCherry was used as control virus (WT). A pressor response to L-glutamate in the injection site served as confirmatory stereotactic target hit. RVL-targeted ablation of PRR resulted in lower BP responses to DOCA-salt in females (WT=115±3 vs KO=104±4 mmHg; p <0.05; n=8), but not males (n=5-8), only during the first 3 days of DOCA-salt treatment. However, at day 13 of DOCA-salt treatment, female PRR RVL-KO unexpectedly exhibited exaggerated increase in systolic BP (WT=149±3 vs KO=163±3 mmHg; p =0.004; n=8) and pulse pressure (WT=31±4 vs KO=45±4 mmHg; p =0.02; n=8) when compared to control. Next, mice were challenged with an intraperitoneal hypertonic saline injection equivalent to 10% of their body weight followed by 4 hours of urine collection. Urinary sodium excretion in female PRR RVL-KO was significantly lower when compared to WT ( p <0.05). These data indicate that the role of PRR in the RVL is sex-dependent and biphasic. That is, PRR contributes to the pressor response during the initial stage of DOCA-salt HT in females, presumably by facilitating the generation of angiotensin peptides in the RVL, while it plays a protective role by promoting renal sodium excretion and preventing elevation of systolic BP during the maintenance stage of DOCA-salt HT. This study suggests that distinct PRR expressing cell populations might elicit diverging physiological functions within the RVL.

Abstract MP27: Adipose-derived Human Soluble (Pro)renin Receptor Causes Resistance To Losartan Treatment In High-Fat Diet Male And Female Mice

Obesity, affecting more that 37% of the US, contributes to hypertension. Despite the use of one or more anti-hypertensive treatments, 48% of the hypertensive population remains with resistant hypertension, which prompts the development for new therapeutic targets. We demonstrated that obesity increased the expression of prorenin receptor (PRR) in the adipose tissue and elevated plasma soluble PRR (sPRR). In addition, the infusion of mouse sPRR increased blood pressure in male mice fed high fat-diet (HF); indicating that adipose-derived sPRR could increase circulating sPRR and contribute to hypertension. However, there is a critical gap in the functional role of human sPRR in obesity-hypertension. In this study, we aim to define whether adipose-derived human sPRR contributes to obesity-hypertension. Human sPRR-Myc-tag transgenic mice were bred with mice expressing adiponectin/Cre to selectively express human sPRR in adipocytes (adi-HsPRR). Adi-HsPRR and control littermate (CTL) male and female mice were fed HF-diet for 20 weeks (N=8-15/group). Body weight was assessed weekly and body composition monthly. Blood pressure was measured by telemetry after 15 weeks of diet. Adipose-derived human sPRR did not significantly elevate body weight or fat mass (Male: CTL.18.3±1.0g; adi-HsPRR. 17.5±0.8g. Female: CTL. 15.6±1.5g; adi-HsPRR. 11.9±1.3g; p>0.05). Systolic blood pressure (SBP) significantly increased in HF-fed male and female mice however; adipose-derived human sPRR did not further elevate SBP (24h SBP. Male: CTL. 136.0±1.7 mmHg; adi-HsPRR: 133.4±1.5mmHg; Female: CTL. 131.9±2.8 mmHg; adi-HsPRR: 130.6±3.1 mmHg; p>0.05). Surprisingly, the anti-hypertensive effect of losartan (Los) to lower blood pressure was significantly reduced in adi-HsPRR male and female mice (Male: CTL. ΔSBP: -12.1±1.5 ΔmmHg; adi-HsPRR: -7.8±0.6 ΔmmHg; Female: CTL. ΔSBP: -13.4±1.1 ΔmmHg; adi-HsPRR: -5.7±2.3 ΔmmHg; p<0.05). In 3T3-L1 cells, sPRR significantly increased phosphorylation of ERK1/2, which was not completely blunted by Los indicating that human sPRR could act as a partial agonist of AT1R or activate ERK1/2 independently of AT1R. Our data suggests that adipose-derived sPRR does not stimulate AT1R-mediated contractility, instead impairs Los efficacy.

Abstract MP34: Collecting Duct Cells-derived Human Sprr Impairs The Antihypertensive Effects Of Losartan And Upregulates Erk1/2 And Aqp2 Expression

Recent studies showed that soluble prorenin receptor (sPRR) plays an important role in blood pressure regulation and in water balance. In rodent models, sPRR contributes to AngII production by increasing renin activity, systolic blood pressure (SBP) and aquaporin2 (AQP2)-dependent antidiuretic action. However, there is a gap of knowledge concerning the functional role of locally produced sPRR from the kidney. Therefore, we evaluated the kidney-derived human sPRR role in SBP control and fluid homeostasis. Human sPRR-Myc-tag transgenic mice were bred with mice expressing Hoxb7/Cre to selectively express human sPRR in the collecting duct (RHsPRR). RHsPRR and control (CTL) male mice were fed a standard diet for 10 months (n=8-11/group). Body weight and urine volume were examined and SBP measured by radiotelemetry. Western blot analysis depicted the presence of human sPRR-Myc-tag (28 KDa) in the cortex and medulla of RHsPRR male mice validating the humanized mouse model. Body weight did not change and 24hr-SBP was similar between CLT and RHsPRR mice (128±2 and 122±5 mmHg, respectively). However, the chronic response to losartan treatment was reduced in RHsPRR compared to CTL (ΔSBP: CTL: -9±3; RHsPRR: -5±1 mmHg, P<0.05). Kidney-derived human sPRR did not change GFR (838±75 vs 1088±163 μl/min/100g BW) and urinary vasopressin (0.62±0.21; 0.72±0.20 ng/mg creatinine), while modestly decreasing urine excretion rate by ~40% (CTL: 1.04±0.20; RHsPRR: 0.57±0.25 ml/day). Furthermore, RHsPRR mice had higher AQP2 protein expression in renal cortex (CTL: 0.24±0.07; RHsPRR: 4.11±0.70 AU, P<0.05) and medulla (CTL: 0.11±0.04; RHsPRR: 4.03±1.74 AU, P<0.05) than CTL mice. Kidney-derived human sPRR significantly increased phosphorylation of ERK 1/2 in the cortex compared to CTL (CTL: 5.4±1.0; RHsPRR: 9.2±1.4 AU, P<0.05), an MAPK involved in the regulation of water balance. In addition, RHsPRR mice showed increased plasma osmolality compared to CTL mice (CTL: 349±2; RHsPRR: 357±2 mOsm/kg, P<0.05). Overall, our data suggest that renal human sPRR could contribute to the increase in plasma tonicity by promoting the activation of ERK1/2-AQP2 pathway. Whether this signaling is associated with impaired antihypertensive effects of AT1R blockage remains under investigation.

High glucose induces trafficking of prorenin receptor and stimulates profibrotic factors in the collecting duct

Growing evidence indicates that prorenin receptor (PRR) is upregulated in collecting duct (CD) of diabetic kidney. Prorenin is secreted by the principal CD cells, and is the natural ligand of the PRR. PRR activation stimulates fibrotic factors, including fibronectin, collagen, and transforming growth factor-β (TGF-β) contributing to tubular fibrosis. However, whether high glucose (HG) contributes to this effect is unknown. We tested the hypothesis that HG increases the abundance of PRR at the plasma membrane of the CD cells, thus contributing to the stimulation of downstream fibrotic factors, including TGF-β, collagen I, and fibronectin. We used streptozotocin (STZ) male Sprague–Dawley rats to induce hyperglycemia for 7 days. At the end of the study, STZ-induced rats showed increased prorenin, renin, and angiotensin (Ang) II in the renal inner medulla and urine, along with augmented downstream fibrotic factors TGF-β, collagen I, and fibronectin. STZ rats showed upregulation of PRR in the renal medulla and preferential distribution of PRR on the apical aspect of the CD cells. Cultured CD M-1 cells treated with HG (25 mM for 1 h) showed increased PRR in plasma membrane fractions compared to cells treated with normal glucose (5 mM). Increased apical PRR was accompanied by upregulation of TGF-β, collagen I, and fibronectin, while PRR knockdown prevented these effects. Fluorescence resonance energy transfer experiments in M-1 cells demonstrated augmented prorenin activity during HG conditions. The data indicate HG stimulates profibrotic factors by inducing PRR translocation to the plasma membrane in CD cells, which in perspective, might be a novel mechanism underlying the development of tubulointerstitial fibrosis in diabetes mellitus.

Soluble (pro)renin receptor: a novel ligand for angiotensin II type 1 receptor?

This commentary highlights the study entitled ‘Soluble (pro)renin receptor induces endothelial dysfunction and hypertension in mice with diet-induced obesity via activation of angiotensin II type 1 receptor’ presented by Fu et al. published in Clinical Science (Clin Sci (Lond) (2021) 135(6), https://doi.org/10.1042/CS20201047). The authors evaluated the role of the soluble (pro)renin receptor (sPRR), a cleavage product of the prorenin receptor (PRR) by the site 1 protease, as a ligand for angiotensin II type 1 receptor (AT1R). They presented for the first time that sPRR directly interacts with AT1R, causing nuclear factor-κB activation, inflammation, apoptosis, and endothelial dysfunction in primary human umbilical vein endothelial cells (HUVECs). Furthermore, the interaction between sPRR and AT1R was responsible for endothelial dysfunction and hypertension in diet-induced obesity mice. These results provide a potential mechanism for obesity-induced endothelial dysfunction and hypertension. Thus, the sPRR/AT1R complex may be a novel therapeutic target for cardiovascular diseases associated with endothelial dysfunction.

Sex differences in soluble prorenin receptor in patients with type 2 diabetes

Background The soluble prorenin receptor (sPRR), a member of the renin-angiotensin system (RAS), is elevated in plasma of patients with preeclampsia, hypertension, chronic kidney disease (CKD), and type 2 diabetes. Our goal was to examine the relationship between sPRR and RAS activation to define whether sexual dimorphisms in sPRR might explain sex disparities in renal outcomes in patients with type 2 diabetes. Methods Two hundred sixty-nine participants were included in the study (mean age, 48 ± 16 years; 42% men, 58% women), including 173 controls and 96 subjects with type 2 diabetes. In plasma and urine, we measured sPRR, plasma renin activity (PRA), and prorenin. In the urine, we also measured angiotensinogen along with other biomarkers of renal dysfunction. Results Plasma sPRR and PRA were significantly higher in women with type 2 diabetes compared to men. In these women, plasma sPRR was positively correlated with PRA, age, and body mass index (BMI). In contrast, in men the sPRR in urine but not in plasma positively correlated with eGFR in urine, but negatively correlated with urine renin activity, plasma glucose, age, and BMI. Conclusions In patients with type 2 diabetes, sPRR contributes to RAS stimulation in a sex-dependent fashion. In diabetic women, increased plasma sPRR parallels the activation of systemic RAS; while in diabetic men, decreased sPRR in urine matches intrarenal RAS stimulation. sPRR might be a potential indicator of intrarenal RAS activation and renal dysfunction in men and women with type 2 diabetes.