Intrarenal Renin-angiotensin System Research Articles

Sexually Dimorphic Gene Expression in Rat Proximal Tubules Suggests Activation of the Intrarenal Renin Angiotensin System and Elevated Transport Rates in Males

Introduction: Sexual dimorphism affects various organ systems, including renal and cardiovascular. The renin-angiotensin system (RAS) plays a pivotal role in regulating fluid homeostasis and blood pressure, with males being generally more sensitive to the hypertensive actions of angiotensin II (AngII). Proximal tubules (PT)s reabsorb 60-70% of filtered water, sodium, and bicarbonate and present sexually dimorphic biology. In addition, PTs are a key element of the intrarenal RAS and the production site of angiotensinogen ( Agt, AGT) and derived bioactive peptides. These peptides exert autocrine, as well as paracrine effects in distal portions of the nephron, regulating salt and water reabsorption. Hypothesis: We hypothesize that the increased sensitivity to the hypertensive actions of AngII in males is due to activation of the intrarenal RAS. Methods: We used 3 male and 3 female pools of whole kidney single-cell RNAseq transcriptomes to study gene expression differences across sexes in different segments of the nephron. Results: We identified sex-differentially expressed genes (DEGs) in all segments of the nephron, with the majority of DEG mapping to the PT. Analyzing all three PT segments together, we found 86 upregulated genes in females and 104 in males. Pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) highlighted pathways associated with glutathione biosynthesis and metabolism in females, while males presented greater expression of genes associated with the tricarboxylic acid cycle and mineral absorption, including the γ-subunit of the Na,K-ATPase ( Fxyd2). Differential expression of genes on each sub-segment of the PTs, namely S1, S2, and S3, showed the following number of upregulated genes: Females: 39, 37, and 73 in S1, S2, and S3, respectively; and Males: 67, 57, and 105 in S1, S2, and S3, respectively. This data indicates that S3 exhibits the largest sexually dimorphic transcriptomes. Pathway enrichment on S3 DEG in both males and females showed similar enrichment terms as in whole PTs. However, at this resolution, males also present upregulation of RAS genes, including Agt, and two proteases involved in the metabolism of angiotensin peptides: aminopeptidase A ( Enpep, APA) and prolyl endopeptidase ( Prep, PEP). APA and PEP can both cleave AngII to bioactive peptides AngIII and Ang(1-7), respectively. Conclusion: We conclude that the intrarenal RAS is upregulated in male PT.S3. The increase in AGT and proteases capable of metabolizing AngII suggest that this peptide may be elevated. Analyzing the expression of RAS genes alone does not allow us to infer a resultant effect on Na handling, as AngII, AngIII, and Ang(1-7) could exert both natriuretic and anti-natriuretic effects. However, enrichment terms associated with mineral transport and energy demands suggest active mineral transport prevails in males. Funding sources: This work was supported in part by CWRU BGT670107 and NIH-NIDDK DK128304 grants to AGV. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Correlation between Urinary Angiotensinogen (AGT) and Albuminuria in Chronic Kidney Disease (CKD)

Chronic kidney disease (CKD) is a global health concern associated with significant morbidity and mortality. Albuminuria, a hallmark of kidney damage, is a strong predictor of CKD progression and adverse outcomes. Recent research has focused on understanding the correlation between urinary angiotensinogen (AGT) levels, a component of the renin-angiotensin system (RAS), and albuminuria in CKD patients. This review article synthesizes evidence from various studies exploring this correlation and elucidates its mechanistic insights and clinical implications. Clinical studies consistently demonstrate a positive correlation between urinary AGT levels and albuminuria in CKD patients. Elevated urinary AGT levels are associated with increased albuminuria, independent of traditional risk factors, suggesting a potential role for AGT in the pathogenesis of kidney damage and proteinuria in CKD. Mechanistic insights suggest that increased intrarenal RAS activity may lead to enhanced AGT production and secretion, contributing to glomerular hypertension, inflammation, and fibrosis, ultimately promoting albuminuria and CKD progression. The clinical implications of this correlation are profound. Elevated urinary AGT levels may serve as a non-invasive biomarker for assessing intrarenal RAS activity and predicting CKD progression and adverse outcomes. Furthermore, interventions targeting the RAS pathway, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), may help reduce urinary AGT levels and mitigate albuminuria, offering promising therapeutic opportunities for improving patient outcomes in CKD. In conclusion, the correlation between urinary AGT and albuminuria in CKD represents a complex interplay between renal physiology, RAS activation, and kidney damage. By elucidating this correlation, we gain valuable insights into the pathogenesis of CKD and identify urinary AGT as a potential biomarker and therapeutic target for personalized CKD management. Further research is warranted to validate these findings, explore the clinical utility of urinary AGT measurement, and develop targeted interventions aimed at mitigating albuminuria and slowing CKD progression. Through continued investigation, we can strive to improve outcomes and quality of life for patients living with CKD.

Human soluble prorenin receptor expressed in mouse renal collecting duct shows sex-specific effect on cardiorenal function.

Soluble prorenin receptor (sPRR), a component of the renin-angiotensin system (RAS), has been identified as a plasma biomarker for hypertension and cardiovascular diseases in humans. Despite studies showing that sPRR in the kidney is produced by tubular cells in the renal collecting duct (CD), its biological actions modulating cardiorenal function in physiological conditions remain unknown. Therefore, the objective of our study was to investigate whether CD-derived human sPRR (HsPRR) expression influences cardiorenal function and examine sex and circadian differences. Thus, we investigated the status of the intrarenal RAS, water and electrolyte balance, renal filtration capacity, and blood pressure (BP) regulation in CD-HsPRR and control (CTL) mice. CD-HsPRR mice were generated by breeding human sPRR-Myc-tag mice with Hoxb7/Cre mice. Renal sPRR expression increased in CD-HsPRR mice, but circulating sPRR and RAS levels were unchanged compared with CTL mice. Only female littermates expressing CD-HsPRR showed 1) increased 24-h BP, 2) an impaired BP response to an acute dose of losartan and attenuated angiotensin II (ANG II)-induced hypertension, 3) reduced angiotensin-converting enzyme activity and ANG II content in the renal cortex, and 4) decreased glomerular filtration rate, with no changes in natriuresis and kaliuresis despite upregulation of the β-subunit of the epithelial Na+ channel in the renal cortex. These cardiorenal alterations were displayed only during the active phase of the day. Taken together, these data suggest that HsPRR could interact with ANG II type 1 receptors mediating sex-specific, ANG II-independent renal dysfunction and a prohypertensive phenotype in a sex-specific manner.NEW & NOTEWORTHY We successfully generated a humanized mouse model that expresses human sPRR in the collecting duct. Collecting duct-derived human sPRR did not change circulating sPRR and RAS levels but increased daytime BP in female mice while showing an attenuated angiotensin II-dependent pressor response. These findings may aid in elucidating the mechanisms by which women show uncontrolled BP in response to antihypertensive treatments targeting the RAS, improving approaches to reduce uncontrolled BP and chronic kidney disease incidences in women.

The Expression of Alamandine Receptor MrgD in Clear Cell Renal Cell Carcinoma Is Associated with a Worse Prognosis and Unfavorable Response to Antiangiogenic Therapy.

Renal cell carcinoma (RCC) ranks among the most prevalent malignancies in Western countries, marked by its notable heterogeneity, which contributes to an unpredictable clinical trajectory. The insufficiency of dependable biomarkers adds complexity to assessing this tumor progression. Imbalances of several components of the intrarenal renin-angiotensin system (iRAS) significantly impact patient prognoses and responses to first-line immunotherapies. In this study, we analyzed the immunohistochemical expression of the Mas-related G-protein-coupled receptor D (MrgD), which recognizes the novel RAS peptide alamandine (ALA), in a series of 87 clear cell renal cell (CCRCCs), 19 papillary (PRCC), 7 chromophobe (ChRCC) renal cell carcinomas, and 11 renal oncocytomas (RO). MrgD was expressed in all the renal tumor subtypes, with a higher mean staining intensity in the PRCCs, ChRCCs, and ROs. A high expression of MrgD at the tumor center and at the infiltrative front of CCRCC tissues was significantly associated with a high histological grade, large tumor diameter, local invasion, and locoregional node and distant metastasis. Patients with worse 5-year cancer-specific survival and a poorer response to antiangiogenic tyrosine-kinase inhibitors (TKIs) showed higher MrgD expression at the center of their primary tumors. These findings suggest a possible role of MrgD in renal carcinogenetic processes. Further studies are necessary to unveil its potential as a novel biomarker for CCRCC prognosis and response to frontline therapies.

Dapagliflozin attenuates renal fibrosis by suppressing angiotensin II/TGFβ signaling in diabetic mice

AimsDiabetic nephropathy (DN) complicates diabetes Mellitus and intimately relates to intrarenal renin–angiotensin system (RAS) activity. Dapagliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), has been validated to improve renal outcomes in diabetic patients from clinical research by elusive mechanisms. This study explored the presumption that the eagerness activity of intrarenal RAS in DN generated oxidative stress to promote renal fibrosis, and the process can be interrupted by dapagliflozin. MethodsA streptozotocin-induced DN model was established in male C57BL/6J mice. Mice were treated with dapagliflozin or losartan for 14 weeks. Biochemical data, renal fibrosis, oxidative stress, and RAS were measured. ResultsDN mice were characterized by overtly low body weight, high levels of blood glucose, and renal injury. Interrupting SGLT2 and RAS significantly improved renal dysfunction and pathological lesions in DN mice. Consistent with these favorable effects, dapagliflozin revoked the local RAS/oxidative stress and the succeeding transforming growth factor beta (TGFβ) signaling. ConclusionsThis research clarifies that intrarenal RAS activity triggers renal injury in DN, and dapagliflozin attenuates renal fibrosis by suppressing Angiotensin II/TGFβ signaling. It unravels a novel insight into the role of prevention and treatment of SGLT2 inhibitors to DN.

Urinary Angiotensinogen Displays Sexual Dimorphism in Non-Diabetic Humans and Mice with Overweight.

Increased body weight (BW) induces inappropriate renin-angiotensin system (RAS) activation. The activation of the intrarenal RAS is associated with increased urinary angiotensinogen (uAGT), blood pressure (BP), and kidney damage. Here, we examined uAGT excretion levels in young non-diabetic human subjects with overweight (OW) and non-diabetic mice with high-fat diet (HFD)-induced OW. Human subjects (women and men; 20-28 years old) included two groups: (a) overweight (OW, n = 17, BMI ≥ 25); and (b) controls (normal weight (NW; n = 26, BMI ≤ 25). In these subjects, we measured BP, albuminuria, and protein levels of uAGT by ELISA adjusted by urinary creatinine (expressed by uAGT/uCrea). Mice (female and male C57BL/6J mice, 8 ± 2 weeks of age) also included two groups: HFD or normal fat diet (NFD) fed for 8 weeks. We measured BW, fasting blood glucose (FBG), BP by telemetry, albuminuria, and uAGT by ELISA. In humans: (i) no significant changes were observed in BP, albuminuria, and FBG when comparing NW and OW subjects; (ii) multivariate logistic regression analysis of independent predictors related to uAGT/uCrea levels demonstrated a strong association between uAGT and overweight; (iii) urinary reactive oxygen species (ROS) were augmented in men and women with OW; (iv) the uAGT/uCrea ratio was higher in men with OW. However, the uAGT/uCrea values were lower in women even with OW. In mice: (i) males fed an HFD for 8 weeks became OW while females did not; (ii) no changes were observed either in FBG, BP, or albuminuria; (iii) kidney ROS were augmented in OW male mice after 28 weeks but not in females; (iv) OW male mice showed augmented excretion of uAGT but this was undetectable in females fed either NFD or HFD. In humans and mice who are OW, the urinary excretion of AGT differs between males and females and overcomes overt albuminuria.

Angiotensin II type 1 receptor-associated protein deletion combined with angiotensin II stimulation accelerates the development of diabetic kidney disease in mice on a C57BL/6 strain.

The progress in the research field of diabetic kidney disease (DKD) has been disturbed by the lack of reliable animal models. Angiotensin II (Ang II) type 1 receptor (AT1R)-associated protein (ATRAP) promotes internalization of AT1R and selectively inhibits pathological AT1R signaling. In this study, we investigated whether overactivation of the renin-angiotensin system (RAS) through a combination of ATRAP deletion with Ang II stimulation developed a progressive DKD model in C57BL/6 mice, which are resistant to the development of kidney injury. Eight-week-old male systemic ATRAP-knockout mice on the C57BL/6 strain (KO) and their littermate wild-type mice (Ctrl) were divided into five groups: 1) Ctrl, 2) Ctrl-streptozotocin (STZ), 3) KO-STZ, 4) Ctrl-STZ-Ang II, and 5) KO-STZ-Ang II. Ang II was administered for 6 weeks from 4 weeks after STZ administration. At 10 weeks after STZ administration, mice were euthanized to evaluate kidney injuries. Neither ATRAP deletion alone nor Ang II stimulation alone developed a progressive DKD model in STZ-induced diabetic C57BL/6 mice. However, a combination of ATRAP deletion with Ang II stimulation accelerated the development of DKD as manifested by overt albuminuria, glomerular hypertrophy, podocyte loss, mesangial expansion, kidney interstitial fibrosis and functional insufficiency, concomitant with increased angiotensinogen and AT1R expression in the kidneys. In STZ-induced diabetic C57BL/6 mice that are resistant to the development of kidney injury, the combination of ATRAP deletion and Ang II stimulation accelerates the development of DKD, which may be associated with intrarenal RAS overactivation.

Tiliroside Protects against Lipopolysaccharide-Induced Acute Kidney Injury via Intrarenal Renin–Angiotensin System in Mice

Tiliroside, a natural flavonoid, has various biological activities and improves several inflammatory diseases in rodents. However, the effect of Tiliroside on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) and the underlying mechanisms are still unclear. This study aimed to evaluate the potential renoprotective effect of Tiliroside on LPS-induced AKI in mice. Male C57BL/6 mice were intraperitoneally injected with LPS (a single dose, 3 mg/kg) with or without Tiliroside (50 or 200 mg/kg/day for 8 days). Tiliroside administration protected against LPS-induced AKI, as reflected by ameliorated renal dysfunction and histological alterations. LPS-stimulated renal expression of inflammatory cytokines, fibrosis markers, and kidney injury markers in mice was significantly abolished by Tiliroside. This flavonoid also stimulated autophagy flux but inhibited oxidative stress and tubular cell apoptosis in kidneys from LPS-injected mice. Mechanistically, our study showed the regulation of Tiliroside on the intrarenal renin-angiotensin system in LPS-induced AKI mice. Tiliroside treatment suppressed intrarenal AGT, Renin, ACE, and Ang II, but upregulated intrarenal ACE2 and Ang1-7, without affecting plasma Ang II and Ang1-7 levels. Collectively, our data highlight the renoprotective action of Tiliroside on LPS-induced AKI by suppressing inflammation, oxidative stress, and tubular cell apoptosis and activating autophagy flux via the shift towards the intrarenal ACE2/Ang1-7 axis and away from the intrarenal ACE/Ang II axis.

Abstract P221: Soluble (pro)renin Receptor Contributes To 2-kidney, 1-clip-induced Renovascular Hypertension And Ischemic Nephropathy In Mice

The Goldblatt two-kidney, one-clip (2K1C) model features renovascular hypertension and ischemic nephropathy due to overactivated renin-angiotensin system (RAS). Soluble (pro)renin receptor (sPRR), the extracellular domain of (pro)renin receptor (PRR), is primarily generated by site-1 protease (S1P) and implicated as a potential regulator of the RAS and renal function. Here, we examined the function and underlying mechanism of sPRR in 2K1C model by pharmacological inhibition of S1P and genetic mutagenesis of S1P cleavage site. Male 2-mo-old C57BL/6 mice were subjected to the 2K1C procedure or sham operation for 1 month, followed by a 14-day infusion of vehicle or a specific S1P inhibitor PF429242 (PF) (30 mg/kg/day via minipump). The 2K1C procedure induced a 2-fold increase in plasma sPRR, which was reduced by 50% following PF treatment. This was paralleled by improvement of renovascular hypertension (MAP:142.1±1.3 vs. 129.9±2.8mmHg, n=7, p < 0.05) and cardiac hypertrophy (HW/BW:6.3±0.3 vs. 5.0 ± 0.3mg/g, n=7, p < 0.01) accompanied with suppressed cortical and medullary renin activity, active renin content, prorenin content and total renin content in clipped kidney. Meanwhile, cortical and medullary renin mRNA level in clipped kidney was increased 3.8-fold and 5.3-fold, which was reduced by 41% and 55% respectively, following PF treatment. The level of urinary albumin, KIM-1 and NGAL was elevated 5.1-fold, 4.0-fold and 5.7-fold after 2K1C surgery, which was blunted 35%, 49% and 59%, respectively, following PF treatment. Secondly, we employed a novel mouse model with mutagenesis of the cleavage site in PRR (termed as Mutant mice) to verify the role of endogenous sPRR in 2K1C model. Similarly, the hypertensive response and ischemic nephropathy of Mutant mice to 2K1C procedure was blunted (24-day MAP: 2K1C/WT 142.5±2.1 vs. 2K1C/Mutant 128.2±3.2mmHg; 24-day urinary albumin/creatinine: 2K1C/WT 64.9±7.2 vs. 2K1C/Mutant 33.0±1.9mg/g, n=6, p < 0.05), in parallel with attenuated response of systemic and intrarenal RAS. Together, consistent results with the different approaches have established an important role of S1P-derived sPRR in regulation of the RAS and thus the pathogenesis of 2K1C-induced renovascular hypertension and ischemic nephropathy.

Abstract P376: Collecting Duct Renin And Its Receptor Contributes To Unilateral Ureteral Obstruction-induced Kidney Injury Via Activation Of The Intrarenal Ras

The collecting duct (CD) is well known for its role in fine-tuning urinary excretion of electrolytes and water. Emerging evidence suggests a potential role played by the CD in immunity and renal injury but the underlying mechanism largely remains elusive. Within the CD, (pro)renin receptor (PRR) via site-1 protease (S1P)-derived soluble PRR interacts with renin controls the intrarenal renin-angiotensin system (RAS) to regulate Na+ and water balance and blood pressure. The present study attempted to employ mouse models of CD-specific deletion of PRR and renin (CD PRR KO and CD renin KO, respectively) and a specific S1P inhibitor PF-429242 (PF) to explore the pathogenic role of this local system in renal injury induced by unilateral ureteral obstruction (UUO). Male 3-4-month-old CD PRR KO and CD renin KO, and their respective floxed controls were subjected to UUO surgery or sham operation for 3 days, followed by analysis of renal fibrosis, inflammation, and indices of the intrarenal RAS. Male 3-4-month-old C57BL/6 mice were subjected to the same surgical procedures and infused with vehicle or PF at 20 mg/kg/day via minipump for 3 days, followed by analysis of the same parameters. 3-day UUO in floxed mice induced renal abundance of fibronectin and α-SMA by 8.6 folds and 5.8 folds, respectively, as assessed by immunoblotting analysis. qRT-PCR detected similar magnitude of increases in mRNA expression of fibronectin, α-SMA, as well as collagen III, collagen I, and TGF-β in the obstructed kidneys. Similar results were obtained by Trichrome Masson staining. In parallel, the obstructed kidney exhibited 4-5-fold increases in renal medullary renin mRNA, renin activity, and active renin content contrasting to unaltered renin levels in the renal cortex. CD-specific deletion of PRR and renin induced comparable attenuation of various indices of renal fibrosis, inflammation, renal medullary renin levels so did PF treatment. UUO induced a 2-fold increase in plasma sPRR, which was completely blocked by PF treatment. Taken together, our results demonstrated that CD PRR/sPRR-dependent activation of renin represents a key determinant of the intrarenal RAS and thus obstruction-induced renal inflammation and fibrosis.

Abstract P428: Angiotensin II Type 1 Receptor-associated Protein Deletion Combined With Angiotensin II Stimulation Exacerbates Diabetic Kidney Disease In C57BL/6 Mice

The progress in the research field of diabetic kidney disease (DKD) has been disturbed by the lack of reliable animal models. Angiotensin II (Ang II) type 1 receptor (AT1R)-associated protein (ATRAP) promotes internalization of AT1R and selectively inhibits pathological AT1R signaling. In this study, we investigated whether overactivation of the renin-angiotensin system (RAS) through a combination of ATRAP deletion with Ang II stimulation developed a progressive DKD model in C57BL/6 mice, which are resistant to the development of kidney injury. Eight-week-old male systemic ATRAP-knockout mice on the C57BL/6 strain (KO) and their littermate wild-type mice (Ctrl) were divided into five groups: 1) Ctrl, 2) Ctrl-streptozotocin (STZ), 3) KO-STZ, 4) Ctrl-STZ-Ang II, and 5) KO-STZ-Ang II. Ang II was administered for 6 weeks from 4 weeks after STZ administration. At 10 weeks after STZ administration, mice were euthanized to evaluate kidney injuries after measurements of systolic blood pressure (SBP) and urinary albumin excretion (UAE). Neither ATRAP deletion alone nor Ang II stimulation alone developed a progressive DKD model in STZ-induced diabetic C57BL/6 mice (UAE, Ctrl vs Ctrl-STZ vs KO-STZ vs Ctrl-STZ-Ang II: 10.6±2.0 vs 89.0±11.9 vs 69.1±15.0 vs 151.3±55.4 μg/day). However, a combination of ATRAP deletion with Ang II stimulation accelerated the development of DKD as manifested by overt albuminuria (UAE, KO-STZ-Ang II: 852.0±195.6 μg/day, p <0.001 vs Ctrl-STZ-Ang II), glomerular hypertrophy, podocyte loss, mesangial expansion, kidney interstitial fibrosis, and functional insufficiency, concomitant with increased angiotensinogen and AT1R expression in the kidneys. SBP levels were comparable between the Ctrl-STZ-Ang II and KO-STZ-Ang II groups (SBP, Ctrl-STZ-Ang II vs KO-STZ-Ang II: 144±4 vs 154±5 mmHg, p =0.363). In STZ-induced diabetic C57BL/6 mice, the combination of ATRAP deletion and Ang II stimulation accelerates the development of DKD by converting the C57BL/6 strain from being nephropathy-resistant to -susceptible, which may be associated with intrarenal RAS overactivation.

Elevated urinary angiotensinogen excretion links central and renal hemodynamic alterations

Inappropriate activation of intrarenal renin–angiotensin system (RAS) may contribute to the pathogenesis of cardio-renal syndrome (CRS). We aimed to examine the cross-sectional associations of urinary angiotensinogen (AGT) excretion, a biomarker of intrarenal RAS activity, with central (aortic) and renal hemodynamic parameters in middle-aged and older adults, including patients with chronic kidney disease. Aortic and renal hemodynamic parameters were measured using applanation tonometry and duplex ultrasonography in 282 participants. Urinary AGT, liver-type fatty acid-binding protein (L-FABP), and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured for each participant. Multiple linear regression analyses demonstrated that urinary AGT levels were associated with aortic blood pressures, pulsatile measures of renal blood flow, plasma NT-proBNP and urinary L-FABP levels after adjusting for potential covariates, including age, sex, body mass index, estimated glomerular filtration rate (GFR), and medication use. Additionally, when classified based on GFR stages and urinary AGT levels, plasma NT-proBNP and urinary L-FABP levels increased in participants with lower GFR and higher AGT groups. Our findings suggest that urinary AGT excretion is a shared determinant of central (aortic) and renal hemodynamics in middle-aged and older adults, providing clinical evidence for the potential role of intrarenal RAS activity in the development of CRS.

#5289 INTRARENAL RENIN-ANGIOTENSIN SYSTEM ACTIVATION ALTERS RELATIONSHIP BETWEEN SYSTOLIC BLOOD PRESSURE AND PROGRESSION OF CHRONIC KIDNEY DISEASE

Abstract Background and Aims Elevated blood pressure (BP) and intrarenal renin-angiotensin system (RAS) activity are closely related to chronic kidney disease (CKD) progression. However, interrelationship between BP and intrarenal RAS activity on the risk of CKD progression is unknown. Method We analyzed 2,076 participants from the Korean Cohort Study for Outcomes in Patients With CKD. The main exposure was systolic BP (SBP). The urinary angiotensinogen-to-creatinine (u-AGT/Cr) ratio was stratified according to the median value (3.65 μg/gCr). The primary outcome was a composite kidney outcome of a ≥50% decline in estimated glomerular filtration rate from baseline measurement or initiation of kidney replacement therapy. Results During 10,550 person-years of follow-up (median, 5.2 years), the composite outcome occurred in 800 (38.5%) participants. In the multivariable cause-specific hazard model, higher SBP was associated with an increased risk of CKD progression. There was a significant interaction between SBP and u-AGT/Cr ratio on the risk of the primary outcome (P-for-interaction = 0.019). In patients with u-AGT/Cr <3.65 μg/gCr, the hazard ratios (HRs) (95% confidence intervals [CIs]) for SBP 120–129, 130–139, and ≥140 mmHg were 1.47 (1.08-2.01), 1.74 (1.26-2.39), and 2.43 (1.76-3.37), respectively, compared with SBP <120 mmHg. In addition, each 10 mmHg increase in SBP was associated with an 18% higher risk of CKD progression. Moreover, there was a greater decline in the estimated glomerular filtration rate among the higher SBP categories. However, these associations were not observed in patients with u-AGT/Cr ≥3.65 μg/gCr. Conclusion Urinary angiotensinogen levels may modify the association between SBP and adverse kidney outcomes.

#2837 ANGIOTENSIN II TYPE 1A RECEPTOR IN KIDNEY PERICYTES MEDIATES TERTIARY LYMPHOID TISSUE FORMATION AFTER ACUTE KIDNEY INJURY

Abstract Background and Aims Tertiary lymphoid tissues (TLTs) have been demonstrated as a major cause of sustained inflammation after acute kidney injury (AKI), indicating a possible contribution of ensuing chronic kidney disease (CKD). And heterogeneous fibroblasts play the crucial role of induction of TLT by secretion of chemokines. Angiotensin II receptors also express on fibroblasts including pericytes. Our study aimed to investigate whether the blockade of angiotensin II receptor could attenuate TLT formation and ensuing CKD after AKI. Method Ischemia-reperfusion injury (IRI) was used as AKI model. In vivo, systemic angiotensin II receptor blockade was performed by administration of an angiotensin II receptor antagonists called losartan after the recovery of AKI. Cell-specific angiotensin II receptor blockade was performed using Gli1-CreERT2;AT1Rfl/fl mice to knockout angiotensin II type 1a receptor in pericytes. We also investigated the effect of angiotensin II receptor blockade using 3T3 fibroblasts cell line. Results During the 8-month follow-up period after IRI, the activity of intra-renal renin–angiotensin system (RAS) elevated without treatment of losartan. We also displayed that multiple TLTs developed in ensuing CKD after IRI both in a CD-1 and C57BL/6J mice model, which were confirmed by staining of CD3 and B220 representing T and B lymphocytes, respectively. Notably, losartan could not only reduce the size and number of TLT, but also downregulate proinflammatory cytokines such as CXCL13, CCL21 and CCL19 which trigger the initiation of TLT. In vitro, using 3T3 fibroblasts cell line and primary pericytes isolated from kidney after IRI, angiotensin II administration could induce the development of fibroblasts with distinct phenotypes and stimulate production of aforementioned proinflammatory cytokines, particularly CCL19. Additionally, we discovered that angiotensin II-stimulated fibroblasts induced migration of lymphocytes via CCL19 production. Using Gli1-CreERT2;AT1Rfl/fl mice, we found that TLT formation decreased after IRI compared to control groups. Conclusion Losartan can reduce ensuing CKD and TLT formation. Distinctive pericytes inhibition by losartan is the plausible mechanism of amelioration of TLT formation. As a result, losartan might be the promising therapeutic agent to prevent AKI-CKD continuum.

#5736 IDENTIFICATION AND CHARACTERIZATION OF URINARY AND SERUM AMINOACIDS IN DIABETIC KIDNEY DISEASE PATIENTS USING MS-HPLC

Abstract Background and Aims Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease, but few biomarkers of early identification of DKD are available. The aim of the study was to asses new urinary and plasma biomarkers in early stages of DKD, especially in normoalbuminuric type 2 diabetes mellitus (DM) patients. Method This cross-sectional pilot study performed an integrated metabolomic profiling of blood and urine in 90 patients with type 2 DM, classified into 3 stages (30 normo-, 30 micro-, and 30 macroalbuminuric, respectively) and 30 age- and gender-matched healthy controls through high-performance liquid chromatography and mass spectrometry (UPLC-QTOF-ESI* MS). Metabolites were discovered and processed by the advanced Metaboanalyst 5.0. online software using multi- and univariate untargeted analysis. Both multivariate and univariate bioinformatics confirmed the relevance of certain amino acids as biomarkers to be responsible for the occurrence of early renal involvement in the course of type 2 DM. Results A total of 5 metabolites, namely Taurine, Tiglylglycine, Tryptophan, Kynurenic acid, and L-acetylcarnitine were discovered as potential biomarkers for the early identification of DKD. UPLC-QTOF-ESI* MS revealed that: (1) the urinary amino acids levels were increased in normoalbuminuric type 2 DM patients as compared with healthy control subjects; (2) a number of key biomarkers have been identified in the urine, which reflect kidney injury at specific sites along the nephron, including glomerular injury and tubular damage, oxidative stress, inflammation, and activation of the intrarenal renin-angiotensin system. Conclusion High-performance liquid chromatography coupled with mass spectrometry showed that the urinary amino acids levels were increased in normoalbuminuric type 2 DM patients. The results of the study provide a particular metabolomic profile related to blood and urine metabolites which could impact both the glomeruli and the tubules, even in the early stages of DKD.

Intrarenal renin–angiotensin system activation and macrophage infiltrations in pediatric chronic glomerulonephritis

BackgroundThe current study tested the hypothesis that urinary angiotensinogen (UAGT) and urinary monocyte chemoattractant protein-1 (UMCP-1) levels provide a specific index of intrarenal renin–angiotensin system (RAS) status and the degree of infiltration of macrophages associated with RAS blockade and immunosuppressant treatment in pediatric patients with chronic glomerulonephritis.MethodsWe measured baseline UAGT and UMCP-1 levels to examine the correlation between glomerular injury in 48 pediatric chronic glomerulonephritis patients before treatment. Furthermore, we performed immunohistochemical analysis of angiotensinogen (AGT) and CD68 in 27 pediatric chronic glomerulonephritis patients treated with RAS blockades and immunosuppressants for 2 years. Finally, we examined the effects of angiotensin II (Ang II) on monocyte chemoattractant protein-1 (MCP-1) expression in cultured human mesangial cells (MCs).ResultsBaseline UAGT and UMCP-1 levels positively correlated with urinary protein levels, scores for mesangial hypercellularity, rate of crescentic formation, and expression levels of AGT and CD68 in renal tissues (p < 0.05). UAGT and UMCP-1 levels were significantly decreased after RAS blockade and immunosuppressant treatment (p < 0.01), which was accompanied by AGT and CD68 (p < 0.01), as well as the magnitude of glomerular injury. Cultured human MCs showed increased MCP-1 messenger ribonucleic acid and protein levels after Ang II treatment (p < 0.01).ConclusionsThe data indicates that UAGT and UMCP-1 are useful biomarkers of the degree of glomerular injury during RAS blockade and immunosuppressant treatment in pediatric patients with chronic glomerulonephritis.

Intrarenal Renin-Angiotensin System Activation Alters Relationship Between Systolic Blood Pressure and Progression of Chronic Kidney Disease.

Elevated blood pressure and intrarenal renin-angiotensin system activity are closely related to chronic kidney disease (CKD) progression. However, interrelationship between blood pressure and intrarenal renin-angiotensin system activity on the risk of CKD progression is unknown. We analyzed 2076 participants from the Korean Cohort Study for Outcomes in Patients With CKD. The main exposure was systolic blood pressure (SBP). The urinary angiotensinogen-to-creatinine ratio was stratified according to the median value (3.65 μg/gCr). The primary outcome was a composite kidney outcome of a ≥50% decline in estimated glomerular filtration rate from baseline measurement or initiation of kidney replacement therapy. During 10 550 person-years of follow-up (median, 5.2 years), the composite outcome occurred in 800 (38.5%) participants. In the multivariable cause-specific hazard model, higher SBP was associated with an increased risk of CKD progression. There was a significant interaction between SBP and urinary angiotensinogen-to-creatinine ratio on the risk of the primary outcome (P value for interaction=0.019). In patients with urinary angiotensinogen-to-creatinine <3.65 μg/gCr, the hazard ratios (95% CIs) for SBP 120 to 129, 130 to 139, and ≥140 mmHg were 1.46 (1.07-1.99), 1.71 (1.25-2.35), and 2.40 (1.73-3.32), respectively, compared with SBP <120 mmHg. However, these associations were not observed in patients with urinary angiotensinogen-to-creatinine ≥3.65 μg/gCr. In this prospective CKD cohort, higher SBP was associated with CKD progression when urinary angiotensinogen levels were low, while this association was not seen when urinary angiotensinogen levels were high. This finding suggests that intrarenal renin-angiotensin system activity may modify the relationship between SBP and adverse kidney outcome.

(Pro)Renin Receptor Decoy Peptide PRO20 Protects against Oxidative Renal Damage Induced by Advanced Oxidation Protein Products

Chronic kidney disease (CKD) is associated with advanced oxidation protein products (AOPPs). A recent study has shown that AOPP-induced renal tubular injury is mediated by the (pro)renin receptor (PRR). However, it is unclear whether the PRR decoy inhibitor PRO20 can protect against renal damage related to AOPPs in vivo. In this study, we examined the role of the PRR in rats with AOPP-induced renal oxidative damage. Male SD rats were subjected to unilateral nephrectomy, and after a four-day recuperation period, they were randomly divided into four groups (n = 6/group) for four weeks: control (CTR), unmodified rat serum albumin (RSA, 50 mg/kg/day via tail-vein injection), AOPPs-RSA (50 mg/kg/day via tail-vein injection), and AOPPs-RSA + PRO20 (50 mg/kg/day via tail-vein injection + 500 μg/kg/day via subcutaneous injection) groups. PRO20 was administered 3 days before AOPPs-RSA injection. Renal histopathology evaluation was performed by periodic acid-Schiff (PAS) staining, and biochemical parameters related to renal injury and oxidative stress biomarkers were evaluated. The expression of related indicators was quantified by RT-qPCR and immunoblotting analysis. In the results, rats in the AOPPs-RSA group exhibited higher levels of albuminuria, inflammatory cell infiltration, and tubular dilation, along with upregulation of oxidative stress, profibrotic and proinflammatory factors, and elevation of AOPP levels. Meanwhile, in the PRO20 group, these were significantly reduced. Moreover, the levels of almost all components of the renin-angiotensin system (RAS) and Nox4-dependent H2O2 production in urine and the kidneys were elevated by AOPPs-RSA, while they were suppressed by PRO20. Furthermore, AOPPs-RSA rats showed elevated kidney expression of the PRR and soluble PRR (sPRR) and increased renal excretion of sPRR. In summary, these findings suggest that PRR inhibition may serve as a protective mechanism against AOPP-induced nephropathy by inhibiting the intrarenal RAS and Nox4-derived H2O2 mechanisms.

The intrarenal renin-angiotensin system in hypertension: insights from mathematical modelling.

The renin-angiotensin system (RAS) plays a pivotal role in the maintenance of volume homeostasis and blood pressure. In addition to the well-studied systemic RAS, local RAS have been documented in various tissues, including the kidney. Given the role of the intrarenal RAS in the pathogenesis of hypertension, a role established via various pharmacologic and genetic studies, substantial efforts have been made to unravel the processes that govern intrarenal RAS activity. In particular, several mechanisms have been proposed to explain the rise in intrarenal angiotensin II (Ang II) that accompanies Ang II infusion, including increased angiotensin type 1 receptor (AT1R)-mediated uptake of Ang II and enhanced intrarenal Ang II production. However, experimentally isolating their contribution to the intrarenal accumulation of Ang II in Ang II-induced hypertension is challenging, given that they are fundamentally connected. Computational modelling is advantageous because the feedback underlying each mechanism can be removed and the effect on intrarenal Ang II can be studied. In this work, the mechanisms governing the intrarenal accumulation of Ang II during Ang II infusion experiments are delineated and the role of the intrarenal RAS in Ang II-induced hypertension is studied. To accomplish this, a compartmental ODE model of the systemic and intrarenal RAS is developed and Ang II infusion experiments are simulated. Simulations indicate that AT1R-mediated uptake of Ang II is the primary mechanism by which Ang II accumulates in the kidney during Ang II infusion. Enhanced local Ang II production is unnecessary. The results demonstrate the role of the intrarenal RAS in the pathogenesis of Ang II-induced hypertension and consequently, clinical hypertension associated with an overactive RAS.

JS-HR-12: BASIC RESEARCH: ELUCIDATION OF “MOSAIC” PATHOGENESIS OF HYPERTENSION

Basic research plays critical roles in elucidating the “mosaic” pathogenesis of hypertension and developing its treatment. In the field of brain and autonomic nervous system, Chen et al. demonstrated that mild cold exposure elicits autonomic dysregulation, such as increased sympathetic activity and decreased baroreflex sensitivity, and poor sleep quality, causing blood pressure (BP) elevation in normotensive rats. This finding may have critical implications for the cardiovascular event occurrence with low ambient temperature. Domingos-Souza et al. showed that the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of carotid sinus stimulation in spontaneously hypertensive rats (SHRs), proposing a rationale for improving baroreflex activation therapy in humans. In the kidney, Kasacka et al. showed that activity of Wnt/β-catenin pathway is increased in SHRs and 2K1C hypertensive rats, while it is inhibited in DOCA-salt rats. Intrarenal renin-angiotensin system (RAS) is involved in BP regulation. In renal damage with an impaired glomerular filtration barrier, liver-derived angiotensinogen filtered through damaged glomeruli regulates intrarenal RAS activity. Matsuyama et al. further showed that the glomerular filtration of liver-derived angiotensinogen depending on glomerular capillary pressure causes circadian rhythm of the intrarenal RAS. Otsuki et al. revealed that TWIST1, a transcription factor regulating mesodermal embryogenesis, transcriptionally upregulates complement 3, which has been demonstrated to activate intrarenal RAS, in the glomerular mesangial cells from SHRs. The RAS in the vascular system also contributes to BP regulation. Soring nexins (SNXs) are cellular sorting proteins and can regulate the expression and function of G protein-coupled receptors (GPCRs). Liu C et al. demonstrated that SNX1 knockout mice exhibit hypertension through vasoconstriction mediated by increased expression of GPCR AT1R within the arteries. Liu X et al. found that sirtuin 6 (SIRT6) expression is downregulated in the aortae of aged rats and showed that SIRT6 knockdown enhances angiotensin II-induced vascular adventitial aging by activating NF-κB pathway in vitro studies. The studies investigating extracellular vesicles (EVs) and gut microbiota have been increased. Ochiai-Homma et al. showed that pendrin in urinary EVs can be a useful biomarker for diagnosis and treatment of primary aldosteronism. Wu et al. demonstrated that captopril has the potential to rebalance the dysbiotic gut microbiota of DOCA-salt hypertensive rats. Several reports indicate the potential treatment for hypertension and the associated organ damages: rivaroxaban in cardiac hypertrophy; nebivolol, maximakinin, and Pinggan-Qianyang in hypertension; and melatonin and crocin in gestational hypertension.