American Journal of Nephrology

<b><i>Background:</i></b> Cancer immunotherapy, such as anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and anti-programmed death 1 (PD-1), has revolutionized the treatment of malignancies by engaging the patient's own immune system against the tumor rather than targeting the cancer directly. These therapies have demonstrated a significant benefit in the treatment of melanomas and other cancers. <b><i>Summary:</i></b> In order to provide an extensive overview of the renal toxicities induced by these agents, a Medline search was conducted of published literature related to ipilimumab-, pembrolizumab-, and nivolumab-induced kidney toxicity. In addition, primary data from the initial clinical trials of these agents and the FDA adverse reporting system database were also reviewed to determine renal adverse events. Acute interstitial nephritis (AIN), podocytopathy, and hyponatremia were toxicities caused by ipilimumab. The main adverse effect associated with both the PD-1 inhibitors was AIN. The onset of kidney injury seen with PD-1 inhibitors is usually late (3-10 months) compared to CTLA-4 antagonists related renal injury, which happens earlier (2-3 months). PD-1 as opposed to CTLA-4 inhibitors has been associated with kidney rejection in transplantation. Steroids appear to be effective in treating the immune-related adverse effects noted with these agents. <b><i>Key Message:</i></b> Although initially thought to be rare, the incidence rates of renal toxicities might be higher (9.9-29%) as identified by recent studies. As a result, obtaining knowledge about renal toxicities of immune checkpoint inhibitors is extremely important.

A direct causal association between hepatitis B virus (HBV) infection and the development of nephropathy remains controversial. Epidemiological studies have shown that chronic carriage of HBV in some individuals (particularly children) leads to the development of nephrotic syndrome with a strong male predominance, the commonest histological type being membranous nephropathy (MN). Spontaneous clearance of HBV antigens (particularly the HBeAg) leads to abrogation of proteinuria. The isolation of immune complexes in the kidney suggests that the pathogenesis of the disease may have an immune-complex basis. Recent studies showing expression of HBV viral antigens in kidney tissue suggest direct viral-induced pathological alterations and chronic immunologic injury. Biosocial studies have detected no correlation between HBV carriage and proteinuria using both quantitative and qualitative urinary protein analysis. Genetic studies of HLA class I and II genes showed a predisposition to MN but no similar correlation in those with milder degrees of proteinuria. These findings suggest that milder proteinuria is unrelated to HBV carriage or genetic factors but the development of nephropathy, particularly MN, in patients with chronic HBV carriage (HBsAg and/or HBV DNA positive) is based on an interaction of virus and host factors. Although the natural history of the disease tends to remission with preservation of renal function, there is considerable morbidity and a small but significant mortality. Use of naturally occurring cytokines (such as interferon-α2b) and other candidate therapies accelerates clearance of the virus and proteinuria. The most effective tool in reducing the incidence of the disease is the use of HBV vaccines.

<i>Background:</i> Most cases of hyponatremia – serum sodium concentration ([Na⁺]) <135 mEq/l (<135 m<i>M</i>) – are associated with an elevated plasma arginine vasopressin level. This study investigated the efficacy and tolerability of intravenous conivaptan (YM087), a vasopressin V_1A/V₂-receptor antagonist, in treating euvolemic and hypervolemic hyponatremia. <i>Methods:</i> Eighty-four hospitalized patients with euvolemic or hypervolemic hyponatremia (serum [Na⁺] 115 to <130 mEq/l) were randomly assigned to receive intravenous placebo or conivaptan administered as a 30-min, 20-mg loading dose followed by a 96-hour infusion of either 40 or 80 mg/day. The primary efficacy measure was change in serum [Na⁺], measured by the baseline-adjusted area under the [Na⁺]-time curve. The secondary measures included time from first dose to a confirmed ≧4 mEq/l serum [Na⁺] increase, total time patients had serum [Na⁺] ≧4 mEq/l higher than baseline, change in serum [Na⁺] from baseline to the end of treatment, and number of patients with a confirmed ≧6 mEq/l increase in serum [Na⁺] or normal [Na⁺] (≧135 mEq/l). <i>Results:</i> Both conivaptan doses increased area under the [Na⁺]-time curve during the 4-day treatment (p < 0.0001 vs. placebo). From baseline to the end of treatment, the least-squares mean ± standard error serum [Na⁺] increase associated with placebo was 0.8 ± 0.8 mEq/l; with conivaptan 40 mg/day, 6.3 ± 0.7 mEq/l; and with conivaptan 80 mg/day, 9.4 ± 0.8 mEq/l. Conivaptan significantly improved all secondary efficacy measures (p < 0.001 vs. placebo, both doses). Conivaptan was generally well tolerated, although infusion-site reactions led to the withdrawal of 1 (3%) and 4 (15%) of patients given conivaptan 40 and 80 mg/day, respectively. <i>Conclusion:</i> Among patients with euvolemic or hypervolemic hyponatremia, 4-day intravenous infusion of conivaptan 40 mg/day significantly increased serum [Na⁺] and was well tolerated.

<b><i>Background:</i></b> There is no doubt that acute calcineurin inhibitor (CNI) nephrotoxicity exists; however, chronic CNI nephrotoxicity is questionable at best. <b><i>Methods:</i></b> We reviewed the literature to identify original articles related to the use of CNIs in renal and nonrenal solid organ transplantation in order to examine the available evidence about their chronic nephrotoxicity and contribution to graft failure. <b><i>Results:</i></b> Early clinical experience and animal studies support the evidence of CNI nephrotoxicity. These findings evolved into the dogma that CNI nephrotoxicity is the major cause of late renal allograft failure. However, in transplanted kidneys the specific role of chronic CNI nephrotoxicity has been questioned. The emerging literature clearly highlights the lack of solid evidence for the role of CNIs as the sole and major injurious agents that cause chronic renal dysfunction and subsequent graft failure. Most of the evidence available to date is against complete CNI avoidance, and minimization appears to be a more viable strategy. It is becoming increasingly clear that the typical pathological lesions linked to chronic CNI use are highly nonspecific, and most of the chronic changes that have been attributed to chronic CNI nephrotoxicity are the consequences of previously unrecognized immunologic injuries. One needs to keep in mind that the potential risk of side effects of CNI use should be balanced against the risk of rejection. <b><i>Conclusions:</i></b> More research should focus on addressing the true causes of chronic graft dysfunction rather than focusing on the overexaggerated contribution of CNIs to late graft loss.

<i>Background/Aim:</i> Cardiovascular disease is a major cause of mortality in chronic kidney disease patients. Oxidative stress and nitric oxide (NO) deficiency play an important role in vascular endothelial cell dysfunction in chronic kidney disease. To determine if the uremic toxin indoxyl sulfate (IS) induces oxidative stress and inhibits NO production and cell viability in human umbilical vein endothelial cells (HUVEC). <i>Methods:</i> The production of reactive oxygen species (ROS), superoxide, NO and peroxynitrite was measured using a fluorescence microplate reader. The expression of NADPH oxidases (Nox4, Nox2) was analyzed by quantitative reverse transcription-polymerase chain reaction. Cell viability was examined by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate assay. <i>Results:</i> IS induced ROS generation in HUVEC. An inhibitor of NADPH oxidase showed an inhibitory effect on IS-induced ROS production. However, the inhibitors of xanthine oxidase, mitochondrial electron transport and NO synthase did not show any significant effect on IS-induced ROS production. Antioxidants such as vitamin E, N-acetyl-<i>L</i>-cysteine and vitamin C inhibited IS-induced ROS production. IS induced the expression of Nox4 mRNA and the production of superoxide and peroxynitrite in HUVEC. IS inhibited NO production in HUVEC. IS inhibited cell viability, and antioxidants preserve the inhibitory effect of IS on cell viability. <i>Conclusions:</i> IS inhibits NO production and cell viability by inducing ROS through induction of Nox4 in HUVEC.

<i>Background:</i> Aldosterone antagonists have proven efficacy for management of resistant hypertension and proteinuria reduction; however, they are not widely used due to risk of hyperkalemia. This study assesses the risk factors for hyperkalemia in patients with chronic kidney disease (CKD) and resistant hypertension whose blood pressure (BP) is reduced to a guideline goal. <i>Methods:</i> This is a two-center study conducted in university-based hypertension clinics directed by clinical hypertension specialists. Forty-six patients with resistant hypertension and stages 2 or 3 CKD (mean estimated glomerular filtration rate (eGFR) 56.5 ± 16.2 ml/min/1.73 m²) were evaluated for safety and efficacy of aldosterone blockade added to preexisting BP-lowering regimens. All patients were on three mechanistically complementary antihypertensive agents including a diuretic and a renin-angiotensin system blocker. Patients were evaluated after a median of 45 treatment days. The primary endpoint was change in systolic BP. Secondary endpoints included change in serum potassium, creatinine, eGFR, diastolic BP and tolerability. <i>Results:</i> The mean age of the patients studied was 64.9 ± 10.7 years, all were obese and 86% had type 2 diabetes, with 82% being African-American. Addition of aldosterone antagonism yielded a further mean reduction in systolic BP of 14.7 ± 5.1 mm Hg (p = 0.001). Females with BMI >30 and those with a baseline systolic BP >160 mm Hg were more likely to have a greater BP reduction to aldosterone antagonism. In total, 39% of the patients had a >30% decrease in eGFR when the BP goal was achieved. The mean increase in serum potassium was 0.4 mEq/l above baseline (p = 0.001), with 17.3% manifesting hyperkalemia, i.e. serum potassium >5.5 mEq/l. Predictors of hyperkalemia included a baseline eGFR of ≤45 ml/min/1.73 m² in whom serum potassium was >4.5 mEq/l on appropriately dosed diuretics. Contributing risks in this subgroup included a systolic BP reduction of >15 mm Hg associated with an eGFR fall of >30%. <i>Conclusion:</i> Aldosterone antagonism is effective and safe for achieving a BP goal among people with diabetic nephropathy when added to a triple antihypertensive regimen that includes a blocker of the renin-angiotensin system and an appropriately selected and dosed diuretic. Caution is advised when using aldosterone blockade for BP control in people with advanced stage 3 nephropathy with a serum potassium of >4.5 mEq/l for safety reasons.

<b><i>Background:</i></b> Although the number of patients reaching end-stage kidney disease without a biopsy-proven diagnosis is increasing, the utility of renal biopsy is still an object of debate. We analyzed epidemiological data and the main indications for renal biopsy with a systematic, evidence-based review at current literature. <b><i>Summary:</i></b> There is a high discrepancy observed in biopsy rates and in the epidemiology of glomerular diseases worldwide, related to the different time frame of the analyzed reports, lack of data collection, the different reference source population and the heterogeneity of indications. The evidence-based analysis of indications showed that renal biopsy should be crucial in adults with nephrotic syndrome or urinary abnormalities as coexistent hematuria and proteinuria and in corticosteroid resistant-children with severe proteinuria. The knowledge of renal histology can change the clinical management in patients with acute kidney injury significantly, after the exclusion of pre-renal or obstructive causes of kidney damage. Scarce evidence indicates that renal biopsy can be useful in patients with advanced chronic kidney disease and its use should always be considered after weighing the benefits and potential risks. Renal biopsy should be crucial in patients with renal involvement due to systemic disease. In patients with diabetes with atypical features, renal biopsy may be fundamental to diagnose an unexpected parenchymal disease mislabeled as diabetic nephropathy. Finally, in elderly patients, the indications and the risks are not different from those in the general population. <b><i>Key Message:</i></b> Renal biopsy still remains a concrete approach for managing a substantial percentage of renal diseases.

<b><i>Background/Aims:</i></b> Hypokalemia and hyperkalemia are often noted in chronic kidney disease (CKD) patients, but their impact on mortality and end-stage renal disease (ESRD) is less well understood. We aimed at studying the associations between potassium disorders, and mortality and progression to ESRD in a CKD population. <b><i>Methods:</i></b> Using our electronic health record-based CKD registry, 36,359 patients with eGFR <60 ml/min/1.73 m² and potassium levels measured from January 1, 2005 to September 15, 2009 were identified. We examined factors associated with hypokalemia (<3.5 mmol/l) and hyperkalemia (>5.0 mmol/l) using logistic regression models and associations between serum potassium levels (both as continuous and categorical variables) and all-cause mortality or ESRD using Cox-proportional hazards models. <b><i>Results:</i></b> Serum potassium <3.5 mmol/l was noted among 3% and >5.0 mmol/l among 11% of the study population. In the multivariable logistic regression analysis, lower eGFR, diabetes and use of ACE inhibitors or Angiotensin-Receptor Blockers were associated with higher odds of having hyperkalemia. Heart failure and African American race were factors associated with higher odds of hypokalemia. After adjustment for covariates including kidney function, serum potassium <4.0 and >5.0 mmol/l were significantly associated with increased mortality risk, but there was no increased risk for progression to ESRD. Time-dependent repeated measures analysis confirmed these findings. When potassium was examined as a continuous variable, there was a U-shaped association between serum potassium levels and mortality. <b><i>Conclusion:</i></b> In patients with stage 3-4 CKD, serum potassium levels <4.0 and >5.0 mmol/l are associated with higher mortality but not with ESRD.