Is urinary excretion of plasminogen associated with development of pre-eclampsia? An observational, explorative case-control study.
ABSTRACT: OBJECTIVES:Pre-eclampsia (PE) is characterised by renal glomerular endotheliosis and injury to the glomerular filtration barrier with proteinuria. Patients with PE display aberrant filtration of the plasma proenzyme plasminogen which is activated, in the tubular fluid, to plasmin. Plasmin may activate the epithelial sodium channel and cause impaired sodium excretion and contribute to hypertension. An explorative study was conducted to test the association between urinary total plasminogen/plasmin and the development of PE. A positive association was hypothesised. DESIGN:An observational, explorative, nested case-control study of healthy pregnant women. SETTINGS:A Danish County hospital. Samples were collected between 2001 and 2004. PARTICIPANTS:1631 healthy pregnant women participated. Urine samples were collected longitudinally six times during pregnancy. 30 developed PE (cases) and were compared with 146 randomly selected healthy pregnant women (controls). PRIMARY OUTCOME:The association between total plasminogen/plasmin excreted in the urine and PE development is expressed by ORs. Total urinary excretion of plasminogen/plasmin was defined by the urine plasminogen-plasmin/creatinine ratio. SECONDARY OUTCOME:The association between urine (u)-albumin/creatinine ratio, u-aldosterone/creatinine ratio and PE development is expressed by ORs. The correlation between urinary (u-) plasmin and u-aldosterone concentration is expressed as a correlation coefficient. RESULTS:The development of PE in late pregnancy was associated with increased levels of the urine plasminogen-plasmin/creatinine ratio (OR=2.35; 95% CI: 1.12 to 4.93;?p<0.05).U-aldosterone/creatinine ratio did not predict PE at any time. U-albumin/creatinine ratio was positively associated with the development of PE from gestational week 33 (OR=14.04; 95% CI: 2.56 to 76.97;?p<0.01)?and in week 33-35 (OR=14.15; 95% CI: 3.44 to 58.09;?p<0.001) and after gestational week 36, respectively. CONCLUSION:Aberrant filtration of plasminogen may contribute to the pathophysiological features of impaired sodium excretion and hypertension associated with PE late in pregnancy. However, increased urinary albumin levels reveal stronger associations with PE development compared with urinary plasminogen levels.
Project description:Background Diabetic nephropathy is a common diabetes mellitus complication associated with hypertension, proteinuria, and excretion of urinary plasmin that activates the epithelial sodium channel, ENaC, <i>in vitro</i>. Here we hypothesized that the deletion of plasminogen and amiloride treatment protect against hypertension in diabetes mellitus. Methods and Results Male plasminogen knockout (plasminogen-deficient [Plg<sup>-/-</sup>]) and wild-type mice were rendered diabetic with streptozotocin. Arterial blood pressure was recorded continuously by indwelling catheters before and during 10 days of angiotensin II infusion (ANGII; 30-60 ng/kg per minute). The effect of amiloride infusion (2 mg/kg per day, 4 days) was tested in wild-type, diabetic ANGII-treated mice. Streptozotocin increased plasma and urine glucose concentrations and 24-hour urine albumin and plasminogen excretion. Diabetic Plg<sup>-/-</sup> mice displayed larger baseline albuminuria and absence of urine plasminogen. Baseline mean arterial blood pressure did not differ between groups. Although ANGII elevated blood pressure in wild-type, diabetic wild-type, and Plg<sup>-/-</sup> control mice, ANGII did not change blood pressure in diabetic Plg<sup>-/-</sup> mice. Compared with ANGII infusion alone, wild-type ANGII-infused diabetic mice showed blood pressure reduction upon amiloride treatment. There was no difference in plasma renin, ANGII, aldosterone, tissue prorenin receptor, renal inflammation, and fibrosis between groups. Urine from wild-type mice evoked larger amiloride-sensitive current than urine from Plg<sup>-/-</sup> mice with or without diabetes mellitus. Full-length ?-ENaC and ?-ENaC subunit abundances were not changed in kidney homogenates, but the 70 kDa ?-ENaC cleavage product was increased in diabetic versus nondiabetic mice. Conclusions Plasmin promotes hypertension in diabetes mellitus with albuminuria likely through the epithelial sodium channel.
Project description:<h4>Background and objectives</h4>Hypervolemia is a common feature of patients with CKD and associated with hypertension. Recent work has shown stimulation of sodium retention by urinary plasmin during nephrotic syndrome. However, it is unclear whether plasminuria plays a role in patients with stable CKD and non-nephrotic proteinuria.<h4>Design, setting, participants, & measurements</h4>In this cross-sectional study, we analyzed the fluid status of 171 patients with CKD consecutively presenting to our outpatient clinic from 2012 to 2013 using bioimpedance spectroscopy (Body Composition Monitor [BCM]; Fresenius Medical Care, Germany) and its associations to the urinary excretion of plasminogen and plasmin from a spot urine sample. Two-electrode voltage clamp measurements were performed in Xenopus laevis oocytes expressing human epithelial sodium channel to investigate whether plasmin in concentrations found in urine can activate the channel.<h4>Results</h4>Overhydration >5% and overhydration >10% of the extracellular volume were found in 29% and 17% of the patients, respectively, and overhydration was associated with edema, hypertension, higher stages of CKD, and proteinuria. Proteinuria was the strongest independent predictor for overhydration (+0.58 L/1.73 m(2) per 10-fold increase; P<0.001). Urinary excretion of plasmin(ogen) quantified by ELISA correlated strongly with proteinuria (r=0.87) and overhydration (r=0.47). Using a chromogenic substrate, active plasmin was found in 44% of patients and correlated with proteinuria and overhydration. Estimated urinary plasmin concentrations were in a range sufficient to activate epithelial sodium channel currents in vitro. In multivariable analysis, urinary excretion of plasmin(ogen) was associated with overhydration similar to proteinuria.<h4>Conclusions</h4>Hypervolemia in patients with CKD is strongly associated with proteinuria, even in the non-nephrotic range. Protein-rich urine contains high amounts of plasminogen and active plasmin, rendering plasminuria as a possible link between proteinuria and hypervolemia.
Project description:<h4>Introduction</h4>Plasmin and its precursor, plasminogen, are detectable in urine from patients with glomerular disease. Urinary plasmin(ogen) levels correlate with blood pressure (BP) and may contribute to renal Na<sup>+</sup> retention by activating the epithelial Na<sup>+</sup> channel (ENaC). In a longitudinal nested-cohort study, we asked whether urinary plasmin(ogen) levels predict subsequent increase in BP, incident hypertension, or mortality in subjects with type I diabetes, who often develop proteinuria.<h4>Methods</h4>The Pittsburgh Epidemiology of Diabetes Complications (EDC) study followed up type I diabetic subjects for 25 years. Urine specimens from 70 subjects with a spectrum of baseline urinary albumin levels were examined. Outcomes included increased BP after 2 years (?1 SD over baseline systolic or diastolic BP, examined via logistic regression), 25-year incident hypertension (?140/90 mm Hg or initiating BP-lowering medications), and all-cause or cardiovascular mortality, examined using Cox regression.<h4>Results</h4>Subjects experiencing a 2-year increase in BP had higher baseline urinary plasmin(ogen)/creatinine levels (uPl/Cr) than other subjects (<i>P</i> = 0.04); the difference in baseline urinary albumin/creatinine levels (uAlb/Cr) was similar (<i>P</i> = 0.07). Baseline uPl/Cr was associated with increased 25-year hypertension incidence (hazard ratio = 2.05, <i>P</i> = 0.001), all-cause mortality (HR = 2.05, <i>P</i> = 0.01) and cardiovascular mortality (HR = 3.30, <i>P</i> = 0.005), although not independent of uAlb/Cr.<h4>Conclusion</h4>This is the first long-term prospective study addressing clinical outcomes associated with increased urinary plasmin(ogen). Findings are consistent with a role for plasmin(ogen) in promoting increased BP, but also demonstrate the difficulty in distinguishing effects due to plasmin(ogen) from those of albuminuria.
Project description:Primary hyperaldosteronism may be associated with elevated 24-hour urinary potassium excretion. We evaluated the diagnostic value of spot urine (SU) potassium as an index of 24-hour urinary potassium excretion.We measured SU and 24-hour urinary collection potassium and creatinine in 382 patients. Correlations between SU and 24-hour collections were assessed for potassium levels and potassium/creatinine ratios. We used the PAHO formula to estimate 24-hour urinary potassium excretion based on SU potassium level. The agreement between estimated and measured 24-hour urinary potassium excretion was evaluated using the Bland-Altman method. To evaluate diagnostic performance of SU potassium, we calculated areas under the curve (AUC) for SU potassium/creatinine ratio and 24-hour urinary potassium excretion estimated using the PAHO formula.Strongest correlation between SU and 24-hour collection was found for potassium/creatinine ratio (r = 0.69, P<0.001). The PAHO formula underestimated 24-hour urinary potassium excretion by mean 8.3±18 mmol/d (95% limits of agreement -28 to +44 mmol/d). Diagnostic performance of SU potassium/creatinine ratio was borderline good only if 24-hour urinary potassium excretion was largely elevated (AUC 0.802 for 120 mmol K+/24 h) but poor with lower values (AUC 0.696 for 100 mmol K+/24 h, 0.636 for 80 mmol K+/24 h, 0.675 for 40 mmol K+/24 h). Diagnostic performance of 24-hour urinary potassium excretion estimated by the PAHO formula was excellent with values above 120 mmol/d and good with lower values (AUC 0.941 for 120 mmol K+/24 h, 0.819 for 100 mmol K+/24 h, 0.823 for 80 mmol K+/24 h, 0.836 for 40 mmol K+/24 h).Spot urine potassium/creatinine ratio might be a marker of increased 24-hour urinary potassium excretion and a potentially useful screening test when reliable 24-hour urine collection is not available. The PAHO formula allowed estimation of the 24-hour urinary potassium excretion based on SU measurements with reasonable clinical accuracy.
Project description:Urinary albumin excretion and/or albumin to creatinine ratio are associated with CKD and higher risk of cardiovascular events. Several studies investigated the effect of reduced dietary sodium intake on urinary albumin excretion and/or albumin to creatinine ratio in adult patient populations, but the majority was inconclusive because of insufficient statistical power. A meta-analysis of the randomized, controlled trials available could overcome this problem and lead to more definitive conclusions.A systematic search of the online databases available (from 1996 to October of 2014) was conducted of randomized, controlled trials that expressed urinary albumin excretion or albumin to creatinine ratio as the difference between the effects of two different sodium intake regimens. For each study, the mean difference and 95% confidence intervals were pooled using a random effect model. Heterogeneity, publication bias, subgroup, and meta-regression analyses were performed.Eleven studies met the predefined inclusion criteria and provided 23 cohorts with 516 participants and 1-6 weeks of follow-up time. In the pooled analysis, an average reduction in sodium intake of 92 mmol/d was associated with a 32.1% (95% confidence interval, -44.3 to -18.8) reduction in urinary albumin excretion. The effect of sodium restriction was higher in the cohorts including patients on concomitant renin-angiotensin-aldosterone system-blocking therapy, in the studies with intervention lasting at least 2 weeks, and among participants with evidence of kidney damage. A greater reduction of urinary albumin excretion was associated with a higher decrease in BP during the intervention. The analysis of changes in albumin to creatinine ratio provided similar results.This meta-analysis indicates that sodium intake reduction markedly reduces albumin excretion, more so during concomitant renin-angiotensin-aldosterone system-blocking therapy and among patients with kidney damage.
Project description:Serum phosphorus is associated with cardiovascular disease (CVD) in the general population, but may not comprehensively reflect phosphorus homeostasis. Whether urine phosphorus-creatinine ratio (a marker of intestinal absorption) or urine fractional excretion of phosphorus (FEPi; a marker of urinary phosphorus handling) is associated with risk of mortality or CVD is uncertain.Prospective observational study.1,325 community-dwelling men 65 years or older participating in the MrOS Study.Serum phosphorus, urine phosphorus-creatinine ratio, and FEPi.All-cause and CVD death.Mean age was 74 ± 6 (SD) years, estimated glomerular filtration rate was 75 ± 16 mL/min/1.73 m(2), and serum phosphorus level was 3.2 ± 0.4 mg/dL. During a median follow-up of 9.3 years, there were 364 (120 CVD) deaths. After adjustment for demographics, CVD risk factors, and kidney function, the risks of all-cause death in the highest quartiles of serum phosphorus (?3.6 mg/dL), urine phosphorus-creatinine ratio (?0.55), and FEPi (?18%) were 1.63 (95% CI, 1.23-2.17), 1.22 (95% CI, 0.90-1.65), and 0.88 (95% CI, 0.64-1.23), respectively, compared to the lowest quartiles of each. Results were similar for CVD death. Results also were similar in those with estimated glomerular filtration rate ?60 and <60 mL/min/1.73 m(2).Older all-male cohort. Few had advanced chronic kidney disease. Spot urine specimens were used.In community-living older men, higher serum phosphorus concentrations are associated with all-cause and CVD death. In contrast, urine phosphorus-creatinine ratio and FEPi are not. These findings do not support using urine phosphorus-creatinine ratio or FEPi as adjuvant measures to predict risk of mortality or CVD in the general population.
Project description:We reported previously that urinary angiotensinogen (UAGT) levels provide a specific index of the intrarenal renin-angiotensin system (RAS) status in angiotensin II-dependent hypertensive rats. To study this system in humans, we recently developed a human angiotensinogen ELISA. To test the hypothesis that UAGT is increased in hypertensive patients, we recruited 110 adults. Four subjects with estimated glomerular filtration levels <30 mL/min per 1.73 m(2) were excluded because previous studies have already shown that UAGT is highly correlated with estimated glomerular filtration in this stage of chronic kidney disease. Consequently, 106 paired samples of urine and plasma were analyzed from 70 hypertensive patients (39 treated with RAS blockers [angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers; systolic blood pressure: 139+/-3 mm Hg] and 31 not treated with RAS blockers [systolic blood pressure: 151+/-4 mm Hg]) and 36 normotensive subjects (systolic blood pressure: 122+/-2 mm Hg). UAGT, normalized by urinary concentrations of creatinine, were not correlated with race, gender, age, height, body weight, body mass index, fractional excretion of sodium, plasma angiotensinogen levels, or estimated glomerular filtration. However, UAGT/urinary concentration of creatinine was significantly positively correlated with systolic blood pressure, diastolic blood pressure, urinary albumin:creatinine ratio (r=0.5994), and urinary protein:creatinine ratio (r=0.4597). UAGT/urinary concentration of creatinine was significantly greater in hypertensive patients not treated with RAS blockers (25.00+/-4.96 microg/g) compared with normotensive subjects (13.70+/-2.33 microg/g). Importantly, patients treated with RAS blockers exhibited a marked attenuation of this augmentation (13.26+/-2.60 microg/g). These data indicate that UAGT is increased in hypertensive patients, and treatment with RAS blockers suppresses UAGT, suggesting that the efficacy of RAS blockade to reduce the intrarenal RAS activity can be assessed by measurements of UAGT.
Project description:Prostasin is a serine protease present in mammalian urine that increases the activity of the epithelial sodium channel (ENaC) when the two are coexpressed in Xenopus oocytes. To determine if aldosterone, one of the principal regulators of urinary Na reabsorption by the distal nephron, affects prostasin expression, we examined prostasin mRNA and protein in a cultured mouse cortical collecting duct cell line (M-1), whole rats, and patients with primary aldosteronism. Aldosterone treatment of M-1 cells substantially increased prostasin expression and stimulated (22)Na uptake. Urinary excretion of prostasin in rats that were infused with aldosterone likewise increased by approximately 4-fold when compared with the vehicle-infused rats. Finally, urinary excretion of prostasin in patients with primary aldosteronism was substantially increased when compared with normal patients. Adrenalectomy reduced urinary prostasin excretion to control levels, whereas urinary prostasin levels were not altered in patients undergoing surgery for other reasons. In patients with primary aldosteronism, reduction in the urinary excretion of prostasin correlated with the increase in the urinary Na/K ratio. These findings, together with our previous report that prostasin activates the amiloride-sensitive Na currents through ENaC, demonstrate that prostasin regulates Na balance in vivo by virtue of its heightened expression in the presence of aldosterone.
Project description:INTRODUCTION::AZD9977 is a novel mineralocorticoid receptor (MR) modulator, which in preclinical studies demonstrated organ protection without affecting aldosterone-regulated urinary electrolyte excretion. However, when tested in humans, using fludrocortisone as an MR agonist, AZD9977 exhibited similar effects on urinary Na+/K+ ratio as eplerenone. The aim of this study is to understand whether the contradictory results seen in rats and humans are due to the mineralocorticoid used. MATERIALS AND METHODS::Rats were treated with single doses of AZD9977 or eplerenone in combination with either aldosterone or fludrocortisone. Urine was collected for five to six hours and total amounts excreted Na+ and K+ were assessed. RESULTS::AZD9977 dose-dependently increased urinary Na+/K+ ratio in rats when tested against fludrocortisone, but not when tested against aldosterone. Eplerenone dose-dependently increased urinary Na+/K+ ratio when tested against fludrocortisone as well as aldosterone. CONCLUSIONS::The data suggest that the contrasting effects of AZD9977 on urinary electrolyte excretion observed in rats and humans are due to the use of the synthetic mineralocorticoid fludrocortisone. Future clinical studies are required to confirm the reduced electrolyte effects of AZD9977 and the subsequent lower predicted hyperkalemia risk.
Project description:BACKGROUND:The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. T2DM is associated with serious macro- and microvascular complications. In particular, diabetic kidney disease (DKD), which begins with excessive urinary albumin excretion, has a significant impact on affected individuals and is costly to healthcare services. Inhibition of the renin-angiotensin-aldosterone system (RAAS) with angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) significantly reduces albuminuria in diabetes, but this effect is not observed in all those treated. Active vitamin D analogues have been observed to be reno-protective through inhibition of RAAS in animal and human studies. Therefore, it can be hypothesised that an active vitamin D analogue will have an additional benefit to ACEI/ARB treatment for albuminuria reduction in DKD. METHODS:The planned study is an ongoing non-blinded randomised controlled parallel-group trial examining the impact, in individuals with T2DM, of the addition of bioactive vitamin D (calcitriol) to RAAS inhibition treatment using ACI or ARB on urinary albumin excretion over a period of 26 weeks. The primary outcome measure is the urinary albumin creatinine ratio. It is planned for the study to recruit 320 participants. Other outcome measures of interest include 24-h urine albumin (24 h UA) excretion, estimated glomerular filtration rate (eGFR), blood pressure and quality of life. Safety will be assessed throughout. DISCUSSION:If the addition of calcitriol to RAAS inhibition with ACEI or ARB safely results in a significant reduction in albuminuria, the study adds to the body of evidence supporting a role for vitamin D in reno-protection, will inform clinical practice and could result in significant reduction of healthcare costs associated with DKD. TRIAL REGISTRATION:ISRCTN, ISRCTN86739609 . Registered on 7 June 2017. ClinicalTrials.gov, NCT03216564 . Registered on 13 July 2017.