Effects of ACE Inhibition and Angiotensin II Receptor Blockade on Glomerular Basement Membrane Protein Excretion and Charge Selectivity in Type 2 Diabetic Patients

Hypoxia is not the primary mechanism contributing to exercise-induced proteinuria

Introduction

Proteinuria increases at altitude and with exercise, potentially as a result of hypoxia. Using urinary alpha-1 acid glycoprotein (α1-AGP) levels as a sensitive marker of proteinuria, we examined the impact of relative hypoxia due to high altitude and blood pressure-lowering medication on post-exercise proteinuria.

Methods

Twenty individuals were pair-matched for sex, age and ACE genotype. They completed maximal exercise tests once at sea level and twice at altitude (5035 m). Losartan (100 mg/day; angiotensin-receptor blocker) and placebo were randomly assigned within each pair 21 days before ascent. The first altitude exercise test was completed within 24–48 hours of arrival (each pair within ~1 hour). Acetazolamide (125 mg two times per day) was administrated immediately after this test for 48 hours until the second altitude exercise test.

Results

With placebo, post-exercise α1-AGP levels were similar at sea level and altitude. Odds ratio (OR) for increased resting α1-AGP at altitude versus sea level was greater without losartan (2.16 times greater). At altitude, OR for reduced post-exercise α1-AGP (58% lower) was higher with losartan than placebo (2.25 times greater, p=0.059) despite similar pulse oximetry (SpO₂) (p=0.95) between groups. Acetazolamide reduced post-exercise proteinuria by approximately threefold (9.3±9.7 vs 3.6±6.0 μg/min; p=0.025) although changes were not correlated (r=−0.10) with significant improvements in SpO₂ (69.1%±4.5% vs 75.8%±3.8%; p=0.001).

Discussion

Profound systemic hypoxia imposed by altitude does not result in greater post-exercise proteinuria than sea level. Losartan and acetazolamide may attenuate post-exercise proteinuria, however further research is warranted.

Comparing the effect of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers on renal function decline in diabetes

AIM

To compare effectiveness of angiotensin-converting enzyme inhibitors (ACEis)/angiotensin receptor blockers (ARBs) for protecting Type 2 diabetes mellitus (DM2) patients from renal function decline in a real-world setting.

METHODS

Retrospective cohort study of new ACEi/ARB users in 2007-2012 in an unselected primary care DM2 population. Outcome is decline in renal function stage (combining estimated glomerular filtration rate and albuminuria). Patients were matched on a propensity score. Extended Cox models with time-varying covariates were used to estimate hazard ratios of outcome.

RESULTS

The time to renal function decline for ARB users was slightly, but not significantly longer than for ACEi users (hazard ratio: 0.80; 95% CI: 0.58-1.10; p = 0.166).

CONCLUSION

This study did not show significant differences between the classes in preventing renal function decline in DM2 patients in primary care.

Renin-Angiotensin System Inhibitors and Kidney and Cardiovascular Outcomes in Patients With CKD: A Bayesian Network Meta-analysis of Randomized Clinical Trials

BACKGROUND

There is much uncertainty regarding the relative effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) in populations with chronic kidney disease (CKD).

STUDY DESIGN

Systematic review and Bayesian network meta-analysis.

SETTING & POPULATION

Patients with CKD treated with renin-angiotensin system (RAS) inhibitors.

SELECTION CRITERIA FOR STUDIES

Randomized trials in patients with CKD treated with RAS inhibitors.

PREDICTOR

ACE inhibitors and ARBs compared to each other and to placebo and active controls.

OUTCOME

Primary outcome was kidney failure; secondary outcomes were major cardiovascular events, all-cause death.

RESULTS

119 randomized controlled trials (n = 64,768) were included. ACE inhibitors and ARBs reduced the odds of kidney failure by 39% and 30% (ORs of 0.61 [95% credible interval, 0.47-0.79] and 0.70 [95% credible interval, 0.52-0.89]), respectively, compared to placebo, and by 35% and 25% (ORs of 0.65 [95% credible interval, 0.51-0.80] and 0.75 [95% credible interval, 0.54-0.97]), respectively, compared with other active controls, whereas other active controls did not show evidence of a significant effect on kidney failure. Both ACE inhibitors and ARBs produced odds reductions for major cardiovascular events (ORs of 0.82 [95% credible interval, 0.71-0.92] and 0.76 [95% credible interval, 0.62-0.89], respectively) versus placebo. Comparisons did not show significant effects on risk for cardiovascular death. ACE inhibitors but not ARBs significantly reduced the odds of all-cause death versus active controls (OR, 0.72; 95% credible interval, 0.53-0.92). Compared with ARBs, ACE inhibitors were consistently associated with higher probabilities of reducing kidney failure, cardiovascular death, or all-cause death.

LIMITATIONS

Trials with RAS inhibitor therapy were included; trials with direct comparisons of other active controls with placebo were not included.

CONCLUSIONS

Use of ACE inhibitors or ARBs in people with CKD reduces the risk for kidney failure and cardiovascular events. ACE inhibitors also reduced the risk for all-cause mortality and were possibly superior to ARBs for kidney failure, cardiovascular death, and all-cause mortality in patients with CKD, suggesting that they could be the first choice for treatment in this population.

Effects of ACEIs Versus ARBs on Proteinuria or Albuminuria in Primary Hypertension: A Meta-Analysis of Randomized Trials

Although angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) belong to a family of therapies that block the renin-angiotensin system and are suggested to improve proteinuria/albuminuria, it is unclear which is more effective. To compare the effects of ACEIs and ARBs on proteinuria in primary hypertension by performing a meta-analysis covering randomized controlled trials (RCTs). We systematically searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials from January 1990 to November 2014. Eligible studies were RCTs of ACEI therapy versus ARB therapy that reported the albumin excretion rate (AER), albumin (Alb), and urinary albumin excretion (UAE) as outcomes. Seventeen RCTs, including 17,951 patients (without limit of race, age, or sex) with a mean duration of 62.6 weeks, were included. Pooled analysis suggested that ACEIs and ARBs showed no significant differences in AER/Alb/UAE/24-h urine protein/24-h urine total protein in a comparison of 10 trials (SMD 0.09; 95% CI -0.18-0.36; P = 0.52). No significant differences were observed in urinary protein/creatinine ratio (UPCR)/urinary albumin/creatinine ratio (UACR), or albumin/creatinine ratio (ACR) in 7 trials (SMD 0.15; 95% CI -1.88-2.19; P = 0.88). The total outcome of ACEIs and ARBs also showed no significant difference (SMD 0.13; 95% CI -1.03-1.29; P = 0.83). The efficacies of ACEIs and ARBs in controlling blood pressure as a secondary indicator were also similar (SMD -0.50; 95% CI -1.58-0.58; P = 0.37). Based on a meta-analysis of 17 randomized controlled trials including 17,951 patients, we found that ACEIs and ARBs can reduce urine protein levels, improve blood pressure, and were similarly effective in terms of reducing urinary protein excretion.

Blood pressure, proteinuria, and phosphate as risk factors for progressive kidney disease: a hypothesis

Chronic kidney disease (CKD) affects approximately 500 million people worldwide and is increasingly common in both industrialized and emerging countries. Although the mechanisms underlying the inexorable progression of CKD are incompletely defined, recent discoveries may pave the way to a more comprehensive understanding of the pathophysiology of CKD progression and the development of new therapeutic strategies. In particular, there is accumulating evidence indicating a key role for the complex and yet incompletely understood system of divalent cation regulation, which includes phosphate metabolism and the recently discovered fibroblast growth factor 23 (FGF-23)/klotho system, which seems inextricably associated with vitamin D deficiency. The aim of this review is to discuss the links between high blood pressure, proteinuria, phosphate levels, and CKD progression and explore new therapeutic strategies to win the fight against CKD.

Updated report on comparative effectiveness of ACE inhibitors, ARBs, and direct renin inhibitors for patients with essential hypertension: much more data, little new information

OBJECTIVES

A 2007 systematic review compared angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) in patients with hypertension. Direct renin inhibitors (DRIs) have since been introduced, and significant new research has been published. We sought to update and expand the 2007 review.

DATA SOURCES

We searched MEDLINE and EMBASE (through December 2010) and selected other sources for relevant English-language trials.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

We included studies that directly compared ACE inhibitors, ARBs, and/or DRIs in at least 20 total adults with essential hypertension; had at least 12 weeks of follow-up; and reported at least one outcome of interest. Ninety-seven (97) studies (36 new since 2007) directly comparing ACE inhibitors versus ARBs and three studies directly comparing DRIs to ACE inhibitor inhibitors or ARBs were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

A standard protocol was used to extract data on study design, interventions, population characteristics, and outcomes; evaluate study quality; and summarize the evidence.

RESULTS

In spite of substantial new evidence, none of the conclusions from the 2007 review changed. The level of evidence remains high for equivalence between ACE inhibitors and ARBs for blood pressure lowering and use as single antihypertensive agents, as well as for superiority of ARBs for short-term adverse events (primarily cough). However, the new evidence was insufficient on long-term cardiovascular outcomes, quality of life, progression of renal disease, medication adherence or persistence, rates of angioedema, and differences in key patient subgroups.

LIMITATIONS

Included studies were limited by follow-up duration, protocol heterogeneity, and infrequent reporting on patient subgroups.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Evidence does not support a meaningful difference between ACE inhibitors and ARBs for any outcome except medication side effects. Few, if any, of the questions that were not answered in the 2007 report have been addressed by the 36 new studies. Future research in this area should consider areas of uncertainty and be prioritized accordingly.

Losartan chemistry and its effects via AT1 mechanisms in the kidney

Besides the importance of the renin-angiotensin system (RAS) in the circulation and other organs, the local RAS in the kidney has attracted a great attention in research in last decades. The renal RAS plays an important role in the body fluid homeostasis and long-term cardiovascular regulation. All major components and key enzymes for the establishment of a local RAS as well as two important angiotensin II (Ang II) receptor subtypes, AT1 and AT2 receptors, have been confirmed in the kidney. In additional to renal contribution to the systemic RAS, the intrarenal RAS plays a critical role in the regulation of renal function as well as in the development of kidney disease. Notably, kidney AT1 receptors locating at different cells and compartments inside the kidney are important for normal renal physiological functions and abnormal pathophysiological processes. This mini-review focuses on: 1) the local renal RAS and its receptors, particularly the AT1 receptor and its mechanisms in physiological and pathophysiological processes; and 2) the chemistry of the selective AT1 receptor blocker, losartan, and the potential mechanisms for its actions in the renal RAS-mediated disease.