Renin-Angiotensin System Blockade after Acute Kidney Injury: The Plot Thickens

Mineralocorticoid Receptor Antagonism Attenuates Multiple Organ Failure after Renal Ischemia and Reperfusion in Mice

Renal ischemia reperfusion (IR) injury is a major cause of acute kidney injury (AKI) that is often complicated by multiple organ failure of the liver and intestine. The mineralocorticoid receptor (MR) is activated in patients with renal failure associated with glomerular and tubular damage. We thus investigated whether canrenoic acid (CA), a mineralocorticoid receptor (MR) antagonist, protects against AKI-induced hepatic and intestinal injury, suggesting the underlying mechanisms. Mice were divided into five groups: sham mice, mice subjected to renal IR, and mice pretreated with canrenoic acid (CA; 1 or 10 mg/kg) 30 min prior to renal IR. At 24 h after renal IR, the levels of plasma creatinine, alanine aminotransferase and aldosterone were measured, and structural changes and inflammatory responses of the kidney, liver, and intestine were analyzed. We found that CA treatment reduced plasma creatinine levels, tubular cell death and oxidative stress induced by renal IR. CA treatment also decreased renal neutrophil infiltration and inflammatory cytokine expression and inhibited the release of high-mobility group box 1 induced by renal IR. Consistently, CA treatment reduced renal IR-induced plasma alanine transaminase, hepatocellular injury and neutrophil infiltration, and inflammatory cytokine expression. CA treatment also decreased small intestinal cell death, neutrophil infiltration and inflammatory cytokine expression induced by renal IR. Taken together, we conclude that MR antagonism by CA treatment protects against multiple organ failure in the liver and intestine after renal IR.

The Impact of Angiotensin-Converting Enzyme Inhibitors or Angiotensin II Receptor Blockers on Clinical Outcomes of Acute Kidney Disease Patients: A Systematic Review and Meta-Analysis

Background: Acute kidney injury (AKI) may increase the risk of chronic kidney disease (CKD), development of end-stage renal disease (ESRD), and mortality. However, the impact of exposure to angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (ACEi/ARB) in patients experiencing AKI/acute kidney disease (AKD) is still unclear. Methods: In this systematic review, we searched all relevant studies from PubMed, Embase, Cochrane, Medline, Collaboration Central Register of Controlled Clinical Trials, Cochrane Systematic Reviews, and ClinicalTrials.gov until July 21, 2020. We evaluated whether the exposure to ACEi/ARB after AKI onset alters recovery paths of AKD and impacts risks of all-cause mortality, recurrent AKI, or incident CKD. We rated the certainty of evidence according to Cochrane methods and the GRADE approach. Results: A total of seven articles, involving 70,801 patients, were included in this meta-analysis. The overall patient mortality rate in this meta-analysis was 28.4%. Among AKI patients, all-cause mortality was lower in ACEi/ARB users than in ACEi/ARB nonusers (log odds ratio (OR) -0.37, 95% confidence interval (CI): -0.42--0.32, p < 0.01). The risk of recurrent adverse kidney events after AKI was lower in ACEi/ARB users than in nonusers (logOR -0.25, 95% CI: -0.33--0.18, p < 0.01). The risk of hyperkalemia was higher in ACEi/ARB users than in nonusers (logOR 0.43, 95% CI: 0.27-0.59, p < 0.01). Patients with continued use of ACEi/ARB after AKI also had lower mortality risk than those prior ACEi/ARB users but who did not resume ACEi/ARB during AKD (logOR -0.36, 95% CI: -0.4--0.31, p < 0.01). Conclusions: Exposure to ACEi/ARB after AKI is associated with lower risks of all-cause mortality, recurrent AKI, and progression to incident CKD. Patients with AKI may have a survival benefit by continued use of ACEi/ARB; however, a higher incidence of hyperkalemia associated with ACEi/ARB usage among these patients deserves close clinical monitoring.