Renal Renin-angiotensin System Research Articles

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.

Therapeutic potential of Ganoderma lucidum polysaccharide peptide in Doxorubicin-induced nephropathy: modulation of renin-angiotensin system and proteinuria.

Introduction: In the Doxorubicin (DOX)-induced nephropathy model, proteinuria is a manifestation of progressive kidney injury. The pathophysiology of renal illness is heavily influenced by the renin-angiotensin system (RAS). To reduce renal RAS activation and proteinuria caused by DOX, this study evaluated the effectiveness of Ganoderma lucidum polysaccharide peptide (GL-PP), a new glycopeptide produced from Ganoderma lucidum grown on grass. Methods: Three groups of BALB/c male mice were created: control, DOX, and DOX + GL-PP. GL-PP (100mg/kg) was administered to mice by intraperitoneal injection for 4weeks following a single intravenous injection of DOX (10mg/kg via the tail vein). Results: After 4weeks, full-length and soluble pro(renin) receptor (fPRR/sPRR) overexpression in DOX mouse kidneys, which is crucial for the RAS pathway, was dramatically inhibited by GL-PP therapy. Additionally, GL-PP successfully reduced elevation of urinary renin activity and angiotensin II levels, supporting the idea that GL-PP inhibits RAS activation. Moreover, GL-PP showed a considerable downregulation of nicotinamide adenine nucleotide phosphate oxidase 4 (NOX4) expression and a decrease in hydrogen peroxide (H2O2) levels. GL-PP treatment effectively reduced glomerular and tubular injury induced by DOX, as evidenced by decreased proteinuria, podocyte damage, inflammation, oxidative stress, apoptosis, and fibrosis. Discussion: GL-PP inhibits intrarenal PRR/sPRR-RAS activation and upregulation of NOX4 and H2O2, suggesting potential therapeutic approaches against DOX-induced nephropathy.

#2598 KLOTHO DEFICIENCY INDUCES REGULATORY T CELLS IN MURINE LUPUS NEPHRITIS

Abstract Background and Aims Recent studies demonstrate that klotho deficiency participate in various chronic kidney disease. However, it has not been fully assessed the influence of klotho in autoimmune kidney diseases. On the one hand, klotho is known to binds transforming growth factor β (TGFβ) receptor to antagonize its pathophysiological actions including renal fibrosis. On the other hand, TGFβ is required to generate and maintain regulatory T cells with inducing FOXP3, an important cell population for immunological tolerance. Method NZBWF1 mice were used as a model of lupus nephritis. NZBWF1 mice were housed separately in metabolic cage, and divided into two groups (n=10 for each): one group was treated with daily subcutaneous injection of klotho protein (20 µg/kg/day), and the other received vehicle alone. Systolic blood pressure was measured by tail-cuff method. Glomerular filtration rate was assessed using FITC-inulin. Four weeks later, the animals were killed to harvest the spleen and kidneys for analyses. Results Klotho supplementation suppressed blood pressure, 8-epi-prostaglandin F2a excretion and renal angiotensin II levels (p<0.05 for all) without changes in albuminuria and glomerular filtration rate in NZBWF1 mice. Exogenous klotho protein supplementation increased serum klotho levels, urine klotho excretion, and endogenous renal expression of klotho in NZBWF1 mice (p<0.05 for all). Surprisingly, anti-double strand DNA antibody was slightly elevated in klotho-treated NZBWF1 mice (p<0.05). Glomerular pathology and interstitial cell infiltration were similar between 2 groups. The spleen tended to be greater in klotho-treated group, but statistical significance was not attained. In consistent, CD8+FOXP3+ T cells were unaltered between 2 groups. However, klotho supplementation reduced CD4+FOXP3+ T cells in spleen of NZBWF1 mice (p<0.05). Conclusion The present data indicated that klotho protein supplementation suppressed renal renin-angiotensin system, ameliorating blood pressure and oxidative stress. Our results suggest that klotho supplementation worsened auto-antibody, possibly by inhibiting TGFβ with resultant deterioration in regulatory T cells. The present findings implicate that although klotho may not suite for the management of autoimmune kidney diseases, such as lupus and ANCA-related nephritis, klotho supplementation for dialysis patients could mitigate against the defect in cellular immunity and susceptibility to infections including tuberculosis and COVID-19.

PS-C26-5: RENAL ARTERY REMODELING AND RENAL RENIN ANGIOTENSIN SYSTEM IN CHRONIC KIDNEY DISEASE

Purpose: It has long been hypothesized that renin angiotensin system (RAS) is heterogeneously activated in the kidney and is associated with the development of hypertension, but the mechanism by which RAS hyperactivity occurs is unclear. In this study, we hypothesized that narrowing of the lumen of afferent arteriole in chronic kidney disease (CKD) is associated with increased renal RAS, and investigated whether renal arteriolar remodeling is related to urinary angiotensinogen (UAGT), an index of renal RAS. Methods: Of 172 patients who underwent renal biopsy between 2010 and 2013 at our department, 54 patients with UAGT data and less than 10 arterioles and those on RAS inhibitors were excluded. IgA nephropathy was the most common primary disease (57.4%). Microvascular remodeling was assessed by measuring the wall to lumen ratio (WLR), which was calculated as (outer diameter of arteriole - lumen diameter of arteriole)/interstitial lumen diameter. In addition to clinical parameters, we examined the association of WLR with high-sensitivity C-reactive protein (CRP), oxidative stress markers (dROM), flow-dependent vasodilatory response (%FMD), and UAGT. Results: The mean age and eGFR were 38 years and 81 mL/min/1.73 m2, respectively; Log UAGT showed a positive correlation with Log WLR, LDL, and Log dROM, respectively, and a negative correlation with eGFR. Multiple regression analysis showed that Log WLR was significantly associated with Log UAGT independently of factors such as eGFR and urinary protein (β; = 0.38, p = 0.04). Conclusions: Our results suggest that renal arrteriolar remodeling may be associated with increased renal RAS in CKD patients.

PS-B07-2: EXERCISE TRAINING PREVENTS HIGH FRUCTOSE-INDUCED HYPERTENSION AND RENAL DAMAGES IN DAHL SALT-SENSITIVE RATS

Background: High fructose diet (HFr) causes metabolic syndrome, and HFr-induced hypertension and renal damage are exaggerated in Dahl salt-sensitive (DS) rats. Exercise training (Ex) have antihypertensive and renal protective effects in rats fed HFr, but these effects of Ex are weak in DS rats fed a high-salt diet. This study thus examined the effects of Ex on DS rats fed HFr. Methods: Male DS rats were divided into three groups. The control group was fed a control diet, both the HFr group and the HFr-Ex group were fed a HFr (60% fructose). The HFr-Ex group also underwent treadmill running (20 m/min, 60 min/day, 5 day/ week). After 12 weeks, renal function, histology, and renin-angiotensin system (RAS) were examined. Results: HFr increased blood pressure, urinary albumin, and creatinine clearance, and Ex inhibited these increases. HFr induced glomerular sclerosis, podocyte injury, afferent arteriole thickening, and renal interstitial fibrosis, and Ex ameliorated them. HFr reduced plasma renin activity, and Ex further reduced the activity. HFr also increased the expression of angiotensinogen, renin, angiotensin converting enzyme (ACE), and angiotensin II type1 receptor (AT1R), and Ex restored the ACE expression to the control levels. HFr decreased the expression of ACE2, angiotensin II type2 receptor (AT2R), and Mas receptor (MasR), and Ex restored the ACE2 and MasR expressions to the control levels and further decreased the AT2R expression. HFr increased the ACE activity and decreased the ACE2 activity, and Ex restored these activities to the control levels. Conclusion: Ex prevents HFr-induced hypertension and renal damages in DS rats. The changes in renal RAS may be involved in the mechanism of the antihypertensive and renal protective effects of Ex.

PS-B08-10: COMBINATION OF SYSTEMIC ATRAP DEFICIENCY WITH ANGIOTENSIN II STIMULATION ACCELERATES THE DEVELOPMENT OF DIABETIC NEPHROPATHY IN STREPTOZOTOCIN TREATED MICE

Objective: One of the obstacles toward understanding the pathophysiology of diabetic nephropathy (DN) has been the lack of reliable animal models that faithfully replicate features of human DN. Angiotensin II (Ang II) type 1 receptor (AT1R)-associated protein (ATRAP) promotes internalization of AT1R from the cell surface into the cytoplasm, resulting in the suppression of AT1R signaling pathway. We have recently reported that systemic ATRAP deficiency exaggerates streptozotocin (STZ)-induced DN via an activation of renal renin-angiotensin system (RAS) (Haruhara K, et al. Kidney Int 2022). However, STZ-induced diabetic ATRAP knockout mice still exhibited a modest increase in albuminuria with limited pathological changes just in glomerulus. To establish more robust DN models, we examined the effect of Ang II stimulation on the development of DN in STZ-treated ATRAP knockout mice. Design and method: Male eight weeks old C57BL/6 mice (Ctrl) and systemic ATRAP-knockout mice (KO) were divided into three groups: 1) Ctrl-STZ, 2) Ctrl-STZ-Ang II, and 3) KO-STZ-Ang II. Hyperglycemia was induced by intraperitoneal injection of 55 mg/kg STZ for consecutive 5 days. From 4 weeks after STZ administration, Ang II (1000 ng/kg/min) was continuously administered by osmotic mini-pumps for 6 weeks. During the experimental period, body weights and levels of blood glucose were measured every 2 weeks. At 6 and 10 weeks after STZ administration, 24-hour urine samples were collected in metabolic cages, and urinary albumin excretion (UAE) was evaluated by ELISA. At the end of experimental period, mice were euthanized to evaluate renal pathological changes. Results: During the experimental period, body weight gain and levels of blood glucose were not significantly different between the three groups. Nonetheless, although levels of UAE at 6 weeks after STZ administration were still modest and comparable between the three groups, levels of UAE only in the KO-STZ-Ang II group were remarkably increased compared to those in the Ctrl-STZ and Ctrl-STZ-Ang II groups at 10 weeks after STZ administration (679.1 ± 583.7 vs 69.9 ± 10.0 vs 61.3 ± 8.2 μg/day, respectively). Furthermore, in the KO-STZ-Ang II group, exacerbation of mesangial expansion and interstitial fibrosis was observed. Conclusions: In STZ-induced diabetic mice, combination of systemic ATRAP deficiency with Ang II stimulation accelerated the development of DN, suggesting a potential to become a promising mouse model replicating key features of human DN.

PS-C30-1: URINARY ANGIOTENSINOGEN-MELATONIN RATIO IN GESTATIONAL DIABETES AND PREECLAMPSIA

Objective: A large research portfolio indicates that an activated renal renin-angiotensin system or a deficit on melatonin is associated with several cardiovascular pathologies. In this observational clinical study, we hypothesized that alterations in urinary melatonin or angiotensinogen levels may be altered in two common conditions, preeclampsia and gestational diabetes. Our primary objective was to assess melatonin and angiotensinogen as novel disease biomarkers detectable and quantifiable in the urine of pregnant women with or without pregnancy complications. Design and Methods: This was a concurrent cohort study of pregnant women with selected obstetric pathologies (gestational diabetes, preeclampsia, hypertension and obesity with hypertension). A group of healthy controls was also included. Urinary 6-sulfatoxymelatonin and angiotensinogen were measured by sensitive and specific ELISAs in first morning void urine samples. The patients were included in the cohort consecutively, and the diagnosis was blinded at the level of urine collection. Urinary 6-sulfatoxymelatonin and angiotensinogen levels were investigated in the patients included in the cohort. Results: Urinary levels of angiotensinogen were significantly higher in the gestational diabetes [angiotensinogen/creatinine ratio median (25th, 75th): 0.11 (0.07, 0.18)] and preeclampsia [0.08 (0.06, 0.18)] groups than in those with healthy pregnancy [0.05(0.04, 0.06]; 6-sulfatoxymelatonin levels were significantly lower in the gestational diabetes [ug/h: median (25th, 75th): 0.12(0.08, 0.17)] and preeclampsia [0.12 (0.09, 0.15)] groups than in those with healthy pregnancy [0.20 (0.15, 0.27]. Neither morning void protein/creatinine ratio nor 24-h urine protein estimate were significantly different between the study groups. Conclusion: These results suggest that urinary angiotensinogen levels may indicate an intrarenal RAS activation while melatonin production appears to be defective in gestational diabetes or hypertension. An angiotensinogen/melatonin ratio is suggested as an early biomarker for identification of gestational diabetes or hypertension. This report provides a basis for the potential use of melatonin for the treatment of preeclampsia. A prospective study in a larger number of patients to determine the operative characteristics of these markers as potential diagnostic tests is justified.

Klotho Supplementation Reverses Renal Dysfunction and Interstitial Fibrosis in Remnant Kidney

Introduction: While recent investigations show that klotho exerts renoprotective actions, it has not been fully addressed whether klotho protein supplementation reverses renal damage. Methods: The impacts of subcutaneous klotho supplementation on rats with subtotal nephrectomy were examined. Animals were divided into 3 groups: group 1 (short remnant [SR]): remnant kidney for 4 weeks, group 2 (long remnant [LR]): remnant kidney for 12 weeks, and group 3 (klotho supplementation [KL]): klotho protein (20 μg/kg/day) supplementation on the remnant kidney. Blood pressure, blood and urine compositions with conventional methods such as enzyme-linked immunosorbent assay and radioimmunoassay, kidney histology, and renal expressions of various genes were analyzed. In vitro studies were also performed to support in vivo findings. Results: Klotho protein supplementation decreased albuminuria (−43%), systolic blood pressure (−16%), fibroblast growth factor (FGF) 23 (−51%) and serum phosphate levels (−19%), renal angiotensin II concentration (−43%), fibrosis index (−70%), renal expressions of collagen I (−55%), and transforming growth factor β (−59%) (p p Conclusion: Our data indicated that klotho protein supplementation inactivated renal renin-angiotensin system, reducing blood pressure and albuminuria in remnant kidney. Furthermore, exogenous klotho protein supplementation elevated endogenous klotho expression to increase phosphate excretion with resultant reductions in FGF23 and serum phosphate. Finally, klotho supplementation reversed renal dysfunction and fibrosis in association with improved BMP7 in remnant kidney.

PS-B12-7: PERSISTENT REDUCTION IN RENAL RENIN FOLLOWING EARLY TREATMENT OF SPONTANEOUSLY HYPERTENSIVE RATS WITH LOSARTAN

Objective: Abnormalities of renin-angiotensin system (RAS) and renal function have been reported in young spontaneously hypertensive rats (SHR) and blood pressure (BP) can be permanently reset to lower levels after brief early treatment with RAS inhibitors. We sought to determine whether renal renin was affected long-term by early RAS blockade. Design: Male SHR were treated via minipump from 10–14 weeks of age with vehicle (Veh, n = 12) or losartan (Los, n = 14, 7.5 mg/kg/d). Four Veh and six Los SHR were culled at 14-weeks and the remaining animals at 20-weeks. To control for effects of low BP another group received hydralazine (HZ, n = 6, 1 mg/kg/d) from 10–20 weeks. Methods: At 14- and 20-weeks systolic BP was measured, and kidneys collected. Three micrometer paraffin sections of renal cortices were counterstained with hematoxylin for renin immunolabelling, assessed for each animal as the percentage of labelling in 200 glomeruli which displayed the afferent arteriole entering the glomerulus. Results: At 14-weeks the systolic BP (mean ± SEM) was significantly (P < 0.001 by ANOVA) lower in both the Los (145 ± 7 mmHg) and HZ (153 ± 7 mmHg) SHR compared with Veh (206 ± 6 mmHg). At 20-weeks, the same pattern persisted (Los: 187 ± 6 mmHg; HZ: (155 ± 4 mmHg; Veh: 220 ± 6 mmHg) (P < 0.001 by ANOVA). Renal renin immunolabelling increased dramatically during treatment at 14-weeks (44.8 ± 1.1%) compared with Veh (10.5 ± 1.7%) (P < 0.0001 by ANOVA). However, at 20-weeks renal renin was significantly lower in Los (7.7 ± 0.9%) (P < 0.05 by ANOVA) compared with Veh (11.9 ± 1.2%), while renal renin was significantly higher in HZ kidneys (18.0 ± 1.0%) than both Los and Veh kidneys (P < 0.01 by ANOVA). Conclusions: The persistently low BP in SHR following brief early treatment with losartan is associated with reduced renal renin. Normally one would expect activation of the renal RAS with lower BP, as observed with the hydralazine-treated SHR. These results suggest that long-term reduction in renal renin following brief early RAS blockade in SHR might cause the persistently reduced BP seen in these animals.

Renal angiotensin I-converting enzyme-deficient mice are protected against aristolochic acid nephropathy

The renal renin-angiotensin system (RAS) is involved in the development of chronic kidney disease. Here, we investigated whether mice with reduced renal angiotensin I-converting enzyme (ACE−/−) are protected against aristolochic acid nephropathy (AAN). To further elucidate potential molecular mechanisms, we assessed the renal abundances of several major RAS components. AAN was induced using aristolochic acid I (AAI). Glomerular filtration rate (GFR) was determined using inulin clearance and renal protein abundances of renin, angiotensinogen, angiotensin I-converting enzyme (ACE) 2, and Mas receptor (Mas) were determined in ACE−/− and C57BL/6J control mice by Western blot analyses. Renal ACE activity was determined using a colorimetric assay and renal angiotensin (Ang) (1–7) concentration was determined by ELISA. GFR was similar in vehicle-treated mice of both strains. AAI decreased GFR in controls but not in ACE−/− mice. Furthermore, AAI decreased renal ACE activity in controls but not in ACE−/− mice. Vehicle-treated ACE−/− mice had significantly higher renal ACE2 and Mas protein abundances than controls. AAI decreased renal ACE2 protein abundance in both strains. Furthermore, AAI increased renal Mas protein abundance, although the latter effect did not reach statistical significance in the ACE−/− mice. Renal Ang(1–7) concentration was similar in vehicle-treated mice of both strains. AAI increased renal Ang(1–7) concentration in the ACE−/− mice but not in the controls. Mice with reduced renal ACE are protected against AAN. Our data suggest that in the face of renal ACE deficiency, AAI may activate the ACE2/Ang(1–7)/Mas axis, which in turn may deploy its reno-protective effects.

Exercise Training Prevents High Fructose-Induced Hypertension and Renal Damages in Male Dahl Salt-Sensitive Rats.

High-fructose diet (HFr) causes metabolic syndrome, and HFr-induced hypertension and renal damage are exaggerated in Dahl salt-sensitive (DS) rats. Exercise training (Ex) has antihypertensive and renal protective effects in rats fed HFr; however, there has been little discussion about the DS rats, which exhibit metabolic disturbances. This study thus examined the effects of Ex on DS rats fed HFr. Male DS rats were divided into three groups. The control group was fed a control diet, and both the HFr group and the HFr-Ex group were fed an HFr (60% fructose). The HFr-Ex group also underwent treadmill running (20 m·min -1 , 60 min·d -1 , 5 d·wk -1 ). After 12 wk, renal function, histology, and renin-angiotensin system were examined. HFr increased blood pressure, urinary albumin, and creatinine clearance, and Ex inhibited these increases. HFr induced glomerular sclerosis, podocyte injury, afferent arteriole thickening, and renal interstitial fibrosis, and Ex ameliorated them. HFr reduced plasma renin activity, and Ex further reduced the activity. HFr also increased the expression of angiotensinogen, renin, angiotensin-converting enzyme (ACE), and angiotensin II type 1 receptor, and Ex restored the ACE expression to the control levels. HFr decreased the expression of ACE2, angiotensin II type 2 receptor, and Mas receptor, and Ex restored the ACE2 and Mas receptor expressions to the control levels and further decreased the angiotensin II type 2 receptor expression. HFr increased the ACE activity and decreased the ACE2 activity, and Ex restored these activities to the control levels. Ex prevents HFr-induced hypertension and renal damages in DS rats. The changes in renal renin-angiotensin system may be involved in the mechanism of the antihypertensive and renal protective effects of Ex.

Positive Effect of a Pea-Clam Two-Peptide Composite on Hypertension and Organ Protection in Spontaneously Hypertensive Rats.

In the present study, we prepared pea peptides with high angiotensin-converting enzyme (ACE) inhibitory activity in vitro using an enzymatic hydrolysis of pea protein and compounded them with clam peptides to obtain a pea-clam double peptide. The effects of the two-peptide composite and pea peptides on hypertension and the damage-repair of corresponding organs were studied in spontaneously hypertensive rats (SHRs). We found that both pea peptides and the two-peptide composite significantly reduced the blood pressure upon a single or long-term intragastric administration, with the two-peptide composite being more effective. Mechanistically, we found that the two-peptide composite could regulate the renal renin-angiotensin system (RAS), rebalance gut microbial dysbiosis, decrease renal and myocardial fibrosis, and improve renal and cardiac function and vascular remodeling. Additionally, hippocampal lesions caused by hypertension were also eliminated after two-peptide composite administration. Our research provides a scientific basis for the use of this two-peptide composite as a safe antihypertension ingredient in functional foods.

Maternal Iron Deficiency Programs Rat Offspring Hypertension in Relation to Renin-Angiotensin System and Oxidative Stress.

Hypertension is an important public health challenge, affecting up to 30–50% of adults worldwide. Several epidemiological studies indicate that high blood pressure originates in fetal life—the so-called programming effect or developmental origin of hypertension. Iron-deficiency anemia has become one of the most prevalent nutritional problems globally. Previous animal experiments have shown that prenatal iron-deficiency anemia adversely affects offspring hypertension. However, the underlying mechanism remains unclear. We used a maternal low-iron diet Sprague Dawley rat model to study changes in blood pressure, the renal renin-angiotensin system, oxidative stress, inflammation, and sodium transporters in adult male offspring. Our study revealed that 16-week-old male offspring born to mothers with low dietary iron throughout pregnancy and the lactation period had (1) higher blood pressure, (2) increased renal cortex angiotensin II receptor type 1 and angiotensin-converting enzyme abundance, (3) decreased renal cortex angiotensin II receptor type 2 and MAS abundance, and (4) increased renal 8-hydroxy-2′-deoxyguanosine and interleukin-6 abundance. Improving the iron status of pregnant mothers could influence the development of hypertension in their offspring.

Kidney Angiotensin in Cardiovascular Disease: Formation and Drug Targeting.

The concept of local formation of angiotensin II in the kidney has changed over the last 10–15 years. Local synthesis of angiotensinogen in the proximal tubule has been proposed, combined with prorenin synthesis in the collecting duct. Binding of prorenin via the so-called (pro)renin receptor has been introduced, as well as megalin-mediated uptake of filtered plasma-derived renin-angiotensin system (RAS) components. Moreover, angiotensin metabolites other than angiotensin II [notably angiotensin-(1-7)] exist, and angiotensins exert their effects via three different receptors, of which angiotensin II type 2 and Mas receptors are considered renoprotective, possibly in a sex-specific manner, whereas angiotensin II type 1 (AT1) receptors are believed to be deleterious. Additionally, internalized angiotensin II may stimulate intracellular receptors. Angiotensin-converting enzyme 2 (ACE2) not only generates angiotensin-(1-7) but also acts as coronavirus receptor. Multiple, if not all, cardiovascular diseases involve the kidney RAS, with renal AT1 receptors often being claimed to exert a crucial role. Urinary RAS component levels, depending on filtration, reabsorption, and local release, are believed to reflect renal RAS activity. Finally, both existing drugs (RAS inhibitors, cyclooxygenase inhibitors) and novel drugs (angiotensin receptor/neprilysin inhibitors, sodium-glucose cotransporter-2 inhibitors, soluble ACE2) affect renal angiotensin formation, thereby displaying cardiovascular efficacy. Particular in the case of the latter three, an important question is to what degree they induce renoprotection (e.g., in a renal RAS-dependent manner). This review provides a unifying view, explaining not only how kidney angiotensin formation occurs and how it is affected by drugs but also why drugs are renoprotective when altering the renal RAS.Significance StatementAngiotensin formation in the kidney is widely accepted but little understood, and multiple, often contrasting concepts have been put forward over the last two decades. This paper offers a unifying view, simultaneously explaining how existing and novel drugs exert renoprotection by interfering with kidney angiotensin formation.

Saccharomyces boulardii exerts renoprotection by modulating oxidative stress, renin angiotensin system and uropathogenic microbiota in a murine model of diabetes

AimsWe aimed to investigate whether Saccharomyces boulardii strain might exert renoprotective effects by modulating renal renin angiotensin system, oxidative stress and intestinal microbiota in streptozotocin-diabetic mice. Main methodsThirty-six C57BL/6 male mice were divided into four groups: control (C), control + probiotic (CP), diabetes (D), diabetes + probiotic (DP). Diabetes was induced by one intraperitoneal injection of streptozotocin and Saccharomyces boulardii was administered by oral gavage for 8 weeks. Blood glucose, albuminuria and urinary volume were measured. Renal levels of angiotensin peptides (angiotensin I, II and 1–7) and the activities of angiotensin-converting enzyme (ACE) and ACE2 were determined, besides that, renal morphology, serotonin and dopamine levels and also microbiota composition were analyzed. Key findingsProbiotics significantly increased C-peptide secretion and reduced blood glucose of diabetic animals. Saccharomyces boulardii also improved renal antioxidant defense, restored serotonin and dopamine concentration, and activated the renin-angiotensin system (RAS) vasodilator and antifibrotic axis. The modulation of these markers was associated with a beneficial impact on glomerular structure and renal function of diabetic treated animals. The phenotypic changes induced by Saccharomyces boulardii were also related to modulation of intestinal microbiota, evidenced by the decreased abundance of Proteus and Escherichia-Shigella, considered diabetic nephropathy biomarkers. SignificanceTherefore, probiotic administration to streptozotocin-induced diabetic mice improves kidney structure and function in a murine model and might represent a reasonable strategy to counteract nephropathy-associated maladaptive responses in diabetes.

MO389: Klotho Supplementation Reverses Renal Dysfunction and Interstitial Fibrosis in Remnant Kidney

Abstract BACKGROUND AND AIMS Several studies demonstrate that klotho shows renoprotective actions. However, it has not been assessed whether klotho supplementation is able to reverse the renal injury. METHOD In the present study, the effects of klotho protein supplementation on remnant rat kidneys were assessed using three groups: renal ablation for 4 weeks, renal ablation for 12 weeks and klotho supplementation (20 μg/kg/day). RESULTS Klotho supplementation suppressed blood pressure, albuminuria, renal renin-angiotensin system (RAS), serum phosphate and fibroblast growth factor (FGF) 23 levels, fibrosis index, renal expression of transforming growth factor β and collagen I. Klotho protein supplementation increased glomerular filtration rate (GFR), fractional excretion of phosphate, renal expression of klotho, bone morphogenetic protein (BMP) 7 and superoxide dismutase. CONCLUSION Our data indicated that klotho supplementation reduced blood pressure and albuminuria with inactivation of renal RAS in the remnant kidney. In addition, exogenous klotho protein supplementation increased endogenous klotho expression, facilitating phosphate excretion with reductions in serum phosphate and FGF23. Finally, klotho protein supplementation upregulated BMP7, at least partly contributing to an increase in GFR and reversal of fibrosis in the remnant kidney.

Hypogonadal Hypertension In Male Sprague‐Dawley Rats Is Reversed By Testosterone and its Genomically Inactive Metabolite 5β‐Dihydrotestosterone

Testosterone (TES) and its metabolites are efficacious vasodilators acutely, both in vitro and in vivo; however, their long‐term effects on blood pressure (BP) are unclear. We previously reported that castration (CsX) produced hypertension (HT) in normal male rats, and long‐term TES replacement therapy normalized BP and reduced renal renin‐angiotensin system (RAS) expression. Thus, in the present study, the effects of TES and 5β‐dihydrotestosterone (5β‐DHT), a metabolite with potent and efficacious vasodilator effects but lacking classic androgenic activity, were studied in CsX male Sprague‐Dawley rats. Rats were CsX at 12‐13 weeks age and then studied for 15 weeks. Weekly systolic BP (by tail cuff) revealed a progressive rise in BP over 10 weeks after CsX (110 ± 1.6 vs141 ± 1.2 mmHg). During the next 5 weeks, CsX rats received either TES (CsX + TES‐enanthate, 1.75 mg/kg, 2X/week) or 5β‐DHT‐propionate (CsX + 5β‐DHT, 2.00 mg/kg, 2X/week). BP gradually and progressively declined to normal by 5 weeks in CsX + TES rats (113 ± 1.3). In contrast, BP in CsX + 5β‐DHT rats was biphasic: a dramatic, more rapid decline to normal BP after only one week treatment (111 ± 0.7), and a continued more gradual decline to a hypotensive BP by 5 weeks (91 ± 1.1). Seminal vesicle (SV) weight after 5 weeks of androgen therapy (bioassay for androgenic activity) was 0.3250 ± 0.0180 g/100 g body weight in CsX + TES and 0.0122 ± 0.0006 in CsX + 5β‐DHT. In comparison, SV weights were 0.0160 ± 0.0010 in CsX without TES and 0.2860 ± 0.0110 in intact male rats. These data suggest that:1)endogenous and exogenous TES exert anti‐HT effects in male SD rats; 2) the TES metabolite 5β‐DHT exerts substantially greater, more rapid anti‐HT effects which appear to involve nongenomic, androgen receptor‐independent actions; and 3) while TES effects appear to involve diuretic/natriuretic effects on kidney via inhibition of renal RAS expression (our previous studies), the biphasic anti‐HT effects of 5β‐DHT in the present study appear to involve a rapid vasodilatory effect as well as a slower diuretic/natriuretic effect similar to that of TES. @font‐face {font‐family:“Cambria Math”; panose‐1:2 4 5 3 5 4 6 3 2 4; mso‐font‐charset:0; mso‐generic‐font‐family:roman; mso‐font‐pitch:variable; mso‐font‐signature:‐536870145 1107305727 0 0 415 0;}@font‐face {font‐family:Times; panose‐1:0 0 5 0 0 0 0 2 0 0; mso‐font‐charset:0; mso‐generic‐font‐family:auto; mso‐font‐pitch:variable; mso‐font‐signature:‐536870145 1342185562 0 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal {mso‐style‐unhide:no; mso‐style‐qformat:yes; mso‐style‐parent:“”; margin:0in; mso‐pagination:widow‐orphan; text‐autospace:none; font‐size:12.0pt; font‐family:Times; mso‐fareast‐font‐family:“Times New Roman”; mso‐bidi‐font‐family:“Times New Roman”;}.MsoChpDefault {mso‐style‐type:export‐only; mso‐default‐props:yes; font‐size:11.0pt; mso‐ansi‐font‐size:11.0pt; mso‐bidi‐font‐size:11.0pt; font‐family:“Calibri”,sans‐serif; mso‐ascii‐font‐family:Calibri; mso‐ascii‐theme‐font:minor‐latin; mso‐fareast‐font‐family:Calibri; mso‐fareast‐theme‐font:minor‐latin; mso‐hansi‐font‐family:Calibri; mso‐hansi‐theme‐font:minor‐latin; mso‐bidi‐font‐family:“Times New Roman”; mso‐bidi‐theme‐font:minor‐bidi;}.MsoPapDefault {mso‐style‐type:export‐only; margin‐bottom:10.0pt; line‐height:115%;}div.WordSection1 {page:WordSection1;}

Urinary Angiotensinogen-Melatonin Ratio in Gestational Diabetes and Preeclampsia.

Background: A large research portfolio indicates that an activated renal renin-angiotensin system or a deficit on melatonin is associated with several cardiovascular pathologies. In this observational clinical study, we hypothesized that alterations in urinary melatonin or angiotensinogen levels may be altered in two common conditions, preeclampsia and gestational diabetes. Our study’s primary objective was to assess melatonin and angiotensinogen as novel disease biomarkers detectable and quantifiable in the urine of pregnant women with or without pregnancy complications. Methods: This was a concurrent cohort study of pregnant women with selected obstetric pathologies (gestational diabetes, preeclampsia, hypertension and obesity with hypertension). A group of healthy controls was also included. Urinary 6-sulfatoxymelatonin and angiotensinogen were measured by sensitive and specific ELISAs in first morning void urine samples. The patients were included in the cohort consecutively, and the diagnosis was blinded at the level of urine collection. Urinary 6-sulfatoxymelatonin and angiotensinogen levels were investigated in the patients included in the cohort. Results: Urinary levels of angiotensinogen were significantly higher in the gestational diabetes [angiotensinogen/creatinine ratio median (25th, 75th): 0.11 (0.07, 0.18)] and preeclampsia [0.08 (0.06, 0.18)] groups than in those with healthy pregnancy [0.05(0.04, 0.06]; 6-sulfatoxymelatonin levels were significantly lower in the gestational diabetes [ug/h: median (25th, 75th): 0.12(0.08, 0.17)] and preeclampsia [0.12 (0.09, 0.15)] groups than in those with healthy pregnancy [0.20 (0.15, 0.27]. Neither morning void protein/creatinine ratio nor 24-h urine protein estimate were significantly different between the study groups. Conclusion: These results suggest that urinary angiotensinogen levels may indicate an intrarenal RAS activation while melatonin production appears to be defective in gestational diabetes or hypertension. An angiotensinogen/melatonin ratio is suggested as an early biomarker for identification of gestational diabetes or hypertension. This report provides a basis for the potential use of melatonin for the treatment of preeclampsia. A prospective study in a larger number of patients to determine the operative characteristics of these markers as potential diagnostic tests is justified.

Effects of Exercise Training on the Renin-Angiotensin System in the Kidneys of Dahl Salt-Sensitive Rats.

Exercise training (Ex) has antihypertensive and renal protective effects; however, the precise mechanisms remain unclear. The renal renin-angiotensin system (RAS) plays a vital role in renal function and pathology. Therefore, we investigated the effects of Ex on the renal RAS components in Dahl salt-sensitive (Dahl-S) rats. Male Dahl-S rats were divided into four groups: normal salt diet + sedentary, normal salt diet + Ex, high-salt diet (HS, 8% NaCl) + sedentary, and HS + Ex. Treadmill running was performed for 8 wk in the Ex groups. Ex attenuated the HS-induced renal dysfunction and glomerular injury without causing blood pressure alterations. HS increased urinary excretion of both total and intact angiotensinogen. Ex decreased the HS-induced increased urinary excretion of total angiotensinogen. However, it did not change the HS-induced urinary excretion of intact angiotensinogen, indicating reduced intact angiotensinogen cleaving. Ex restored the HS-induced increased angiotensinogen and angiotensin II type 1 receptor expressions in the outer medulla and the HS-induced increased angiotensin-converting enzyme expression in the cortex. Ex restored the HS-induced decreased renin expression in the cortex and outer medulla, and the HS-induced decreased angiotensin-converting enzyme 2, angiotensin II type 2 receptor, and Mas receptor expressions in the outer medulla. Ex attenuates HS-induced renal dysfunction, glomerular injury, and renal RAS dysregulation in Dahl-S rats.

Association of urinary angiotensinogen with renal arteriolar remodeling in chronic kidney disease.

Renin-angiotensin system (RAS) might be associated with arteriolar remodeling. The present study aimed to explore the hitherto unknown relationship between renal RAS and renal arteriolar remodeling and to elucidate whether altered renal RAS subsequently affects renal function in patients with chronic kidney disease (CKD). In this retrospective study, patients with various CKDs not using RAS inhibitors who underwent renal biopsy were included in cross-sectional and longitudinal analyses. Urinary angiotensinogen (UAGT) levels and wall/lumen ratio (WLR) were determined to evaluate renal RAS and renal arteriolar remodeling, respectively. The association between ln(UAGT) and ln(WLR) was cross-sectionally examined using a liner regression model. Furthermore, the association of ln(UAGT) with subsequent changes in estimated glomerular filtration rate (eGFR) per year were longitudinally examined in the largest subgroup of patients who were diagnosed with IgA nephropathy. In the overall cohort (n = 54), the median age, blood pressures, eGFR, and WLR were 37 years, 120/73 mmHg, 85 ml/min per 1.73 m2, and 0.93, respectively. Ln(UAGT) was significantly and positively associated with ln(WLR) even after adjusting for classical and nonclassical clinical renal risk factors. In patients with IgA nephropathy, higher ln(UAGT) was associated with higher ln(WLR). Ln(UAGT) also tended to be associated with a greater decline in eGFR per year over a median period of 8.7 years, even after adjusting for potential confounding factors. In patients with CKD, renal RAS might be associated with renal arteriolar remodeling and future decline in eGFR, independent of potential risk factors.