Vancomycin-Associated Cast Nephropathy

Serum and urinary biomarkers of vancomycin-induced acute kidney injury: A prospective, observational analysis

Vancomycin, a first-line drug for treating methicillin-resistant Staphylococcus aureus infections, is associated with acute kidney injury (AKI). This study involved an evaluation of biomarkers for AKI detection and their comparison with traditional serum creatinine (SCr). We prospectively enrolled patients scheduled to receive intravenous vancomycin for methicillin-resistant S aureus infection. Blood samples for pharmacokinetic assessment and SCr and cystatin C (CysC) measurements were collected at baseline and on days 3, 7, and 10 from the initiation of vancomycin administration (day 1). Urinary biomarkers, including kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin, and clusterin, were collected from days 1 to 7 and adjusted for urinary creatinine levels. The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Of the 42 patients, 6 experienced vancomycin-induced AKI. On day 7, the change from baseline eGFR using CysC (ΔeGFRCysC) showed a stronger correlation with vancomycin area under the curve (r = -0.634, P < .001) than that using SCr (ΔeGFRSCr; r = -0.437, P = .020). ΔeGFRSCr showed no significant correlation with vancomycin pharmacokinetic in patients with body mass index ≥23. The median (interquartile range) level of KIM-1 (μg/mg) was significantly higher in the AKI group (0.006 [0.005-0.008]) than in the non-AKI group (0.004 [0.001-0.005]) (P = .039, Mann-Whitney U test), with area under the receiver operating characteristic curve (95% confidence interval) of 0.788 (0.587-0.990). Serum CysC, particularly in overweight individuals or those with obesity, along with urinary KIM-1 are important predictors of vancomycin-induced AKI. These results may aid in selecting better biomarkers than traditional SCr for detecting vancomycin-induced AKI.

Effect modification of dosing strategy (AUC or trough) on AKI associated with vancomycin in combination with piperacillin/tazobactam or cefepime and meropenem

Piperacillin-tazobactam (TZP), cefepime (FEP), or meropenem (MEM) and vancomycin (VAN) are commonly used in combination for sepsis. Studies have shown an increased risk of acute kidney injury (AKI) with TZP and VAN compared to FEP or MEM. VAN guidelines recommend area under the curve (AUC) monitoring over trough (Tr) to minimize the risk of AKI. We investigated the association of AKI and MAKE-30 with the two VAN monitoring strategies when used in combination with TZP or FEP/MEM. Adult patients between 2015 and 2019 with VAN > 72 hours were included. Patients with AKI prior to or within 48 hours of VAN or baseline CrCl of ≤30 mL/min were excluded. Four cohorts were defined: FEP/MEM/Tr, FEP/MEM/AUC, TZP/Tr, and TZP/AUC. A Cox Proportional Hazard Model was used to model AKI as a function of the incidence rate of at-risk days, testing monitoring strategy as a treatment effect modification. Multivariable logistic regression was used to model MAKE-30. Overall incidence of AKI was 18.6%; FEP/MEM/Tr = 115 (14.6%), FEP/MEM/AUC = 52 (14.9%), TZP/Tr = 189 (26%), and TZP/AUC = 96 (17.1%) (P < 0.001). Both drug group [(TZP; P = 0.0085)] and monitoring strategy [(Tr; P = 0.0007)] were highly associated with the development of AKI; however, the effect was not modified with interaction term [(TZP*Tr); 0.085)]. The odds of developing MAKE-30 were not different between any group and FEP/MEM/AUC. The effect of VAN/TZP on the development of AKI was not modified by the VAN monitoring strategy (AUC vs trough). MAKE-30 outcomes were not different among the four cohorts.

Vancomycin nephrotoxicity: A comprehensive clinico-pathological study

INTRODUCTION

Vancomycin, a commonly prescribed antibiotic particularly in the setting of multi-drug resistant infections, is limited by its nephrotoxicity. Despite its common occurrence, much remains unknown on the clinicopathologic profile as well as the pathogenesis of vancomycin nephrotoxicity. Clinical studies included patients often with severe comorbidities and concomitant polypharmacy confounding the causal pathogenesis. Animal models cannot recapitulate this complex clinical situation. Kidney biopsy was not commonly performed.

METHODS

To address this limitation, we studied 36 patients who had renal biopsies for acute kidney injury (AKI) for suspicion of vancomycin nephrotoxicity. Detailed renal biopsy evaluation, meticulous evaluation of clinical profiles, and up-to-date follow-up allowed for a diagnostic categorization of vancomycin nephrotoxicity (VNT) in 25 patients and absence of vancomycin nephrotoxicity (NO-VNT) in 11 patients. For careful comparison of these two groups, we proceeded to compile a clinicopathologic and morphologic profiles characteristic for each group.

RESULTS

Patients with VNT had a characteristic clinical profile including a common clinical background, a high serum trough level of vancomycin, a rapidly developed and severe acute kidney injury, and a recovery of renal function often shortly after discontinuation of vancomycin. This clinical course was correlated with characteristic renal biopsy findings including acute tubulointerstitial nephritis of allergic type, frequent granulomatous inflammation, concomitant and pronounced acute tubular necrosis of nephrotoxic type, and vancomycin casts, in the absence of significant tubular atrophy and interstitial fibrosis. This clinico-pathologic profile was different from that of patients with NO-VNT, highlighting its role in the diagnosis, management and pathogenetic exploration of vancomycin nephrotoxicity.

CONCLUSION

Vancomycin nephrotoxicity has a distinctive morphologic and clinical profile, which should facilitate diagnosis, guide treatment and prognostication, and confer pathogenetic insights.

Risk Factors for Teicoplanin-Associated Acute Kidney Injury in Patients with Hematological Malignancies: Focusing on Concomitant Use of Tazobactam/Piperacillin

Patients with hematological malignancies (HM) often receive tazobactam/piperacillin (TAZ/PIPC) and glycopeptide antibiotics for febrile neutropenia. The effect of concomitant use of TAZ/PIPC on risk of teicoplanin (TEIC)-associated acute kidney injury (AKI) remains unclear. We investigated the impact of concomitant TAZ/PIPC use on TEIC-associated AKI in HM patients and identified the risk factors. In this retrospective, single-center, observational cohort study, 203 patients received TEIC, 176 of whom satisfied the selection criteria and were divided into TEIC cohort (no TAZ/PIPC; n = 118) and TEIC + TAZ/PIPC cohort (n = 58). AKI was defined as serum creatinine increase ≥0.3 mg/dL within 48 h or ≥50% from baseline. Incidence of AKI in TEIC cohort before and after propensity score matching was 9.3 and 5.9%, respectively, and that in TEIC + TAZ/PIPC cohort was 10.3 and 11.8%. AKI incidence and risk were not significantly different between two cohorts before (p = 0.829; odds ratio (OR) 1.122, 95% confidence interval (CI) 0.393-3.202) and after matching (p = 0.244; OR 2.133, 95% CI 0.503-9.043). Logistic regression analysis with factors clinically or mechanistically potentially related to TEIC-associated AKI, including concomitant TAZ/PIPC use, as independent variables identified baseline hemoglobin level as the only significant risk factor for TEIC-associated AKI (p = 0.011; OR 0.484, 95% CI 0.276-0.848). In HM patients treated with TEIC, concomitant TAZ/PIPC use did not increase AKI risk whereas lower hemoglobin levels had higher risk for TEIC-associated AKI development, suggesting the necessity to monitor serum creatinine when using TEIC in patients with anemia.

Precision nephrotoxicity testing using 3D in vitro models

Nephrotoxicity is a significant concern during the development of new drugs or when assessing the safety of chemicals in consumer products. Traditional methods for testing nephrotoxicity involve animal models or 2D in vitro cell cultures, the latter of which lack the complexity and functionality of the human kidney. 3D in vitro models are created by culturing human primary kidney cells derived from urine in a 3D microenvironment that mimics the fluid shear stresses of the kidney. Thus, 3D in vitro models provide more accurate and reliable predictions of human nephrotoxicity compared to existing 2D models. In this review, we focus on precision nephrotoxicity testing using 3D in vitro models with human autologous urine-derived kidney cells as a promising approach for evaluating drug safety.

Overview of Antibiotic-Induced Nephrotoxicity

Drug-induced nephrotoxicity accounts for up to 60% of cases of acute kidney injury (AKI) in hospitalized patients and is associated with increased morbidity and mortality in both adults and children. Antibiotics are one of the most common causes of drug-induced nephrotoxicity. Mechanisms of antibiotic-induced nephrotoxicity include glomerular injury, tubular injury or dysfunction, distal tubular obstruction from casts, and acute interstitial nephritis (AIN) mediated by a type IV (delayed-type) hypersensitivity response. Clinical manifestations of antibiotic-induced nephrotoxicity include acute tubular necrosis (ATN), AIN, and Fanconi syndrome. Given the potential nephrotoxic effects of antibiotics on critically ill patients, the use of novel biomarkers can provide information to optimize dosing and duration of treatment and can help prevent nephrotoxicity when traditional markers, such as creatinine, are unreliable. Use of novel kidney specific biomarkers, such as cystatin C and urinary kidney injury molecule-1 (KIM-1), may result in earlier detection of AKI, dose adjustment, or discontinuation of antibiotic and development of nonnephrotoxic antibiotics.

Recombinant Klotho alleviates vancomycin-induced acute kidney injury by upregulating anti-oxidative capacity via JAK2/STAT3/GPx3 axis

Emerging studies support that Klotho protects against different kidney diseases. However, the role of Klotho in vancomycin induced acute kidney injury (Van-AKI) is largely unclear. Hence this study aimed to explore the regulatory mechanism of Klotho in Van-AKI. The mRNA expression of Klotho and the JAK2/STAT3/GPx3 in renal tissue were assessed by RNA sequence analysis after 600 mg/kg Van daily for seven days; Small interfering RNA and recombinant protein are applied to examine the mechanism action of Klotho in vitro and in vivo respectively. Flow cytometry and spectrophotometry detected the expression of reactive oxygen species and antioxidant enzymes. Transmission electron microscopy scanned the structural damage of mitochondria. Western blotting, qPCR, and immunofluorescence were employed to explore the JAK2/STAT3/GPx3 expression. RNA sequence analysis found that Van challenging reduced Klotho and GPx3 expression but increased JAK2/STAT3 in renal tissue. In HK-2 cells, Klotho were decreased by Van in a dose-dependent manner. Klotho siRNA enhanced the production of reactive oxygen species and the cell apoptosis ratio by regulating the JAK2/STAT3, and JAK2/STAT3 inhibitors prevented the decrease of GPx3. Meanwhile, 1 μg/ml recombinant human Klotho showed the opposite function to 120 pmol Klotho siRNA. In Van-AKI BALB/c mice, 20 μg/kg recombinant mouse Klotho once every two days improved the anti-oxidative enzyme expression, mitochondria structure, renal dysfunction, and histological damage. In conclusion, Klotho enhances antioxidant capacity through the JAK2/STAT3/GPx3 axis, which in turn improves Van-AKI.

Contemporary pharmacologic treatments of MRSA for hospitalized adults: rationale for vancomycin versus non-vancomycin therapies as first line agents

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) remains an important pathogen in the hospital setting and causes significant morbidity and mortality each year. Since the initial discovery over 60 years ago, vancomycin has remained a first-line treatment for many different types of MRSA infections. However, significant concerns related to target attainment and nephrotoxicity have spurred efforts to develop more effective agents in the last two decades.

AREAS COVERED

Newer anti-MRSA antibiotics that have been approved since 2000 include linezolid, daptomycin, and ceftaroline. As clinical evidence has accumulated, these newer agents have become more frequently used, and some are now recommended as co-first-line options (along with vancomycin) in clinical practice guidelines. For this review, a scoping review of the literature was conducted to support our findings and recommendations.

EXPERT OPINION

Vancomycin remains an important standard of care for MRSA infections but is limited with respect to nephrotoxicity and rapid target attainment. Newer agents such as linezolid, daptomycin, and ceftaroline have specific indications for treating different types of MRSA infections; however, newer agents also have unique attributes which require consideration during therapy.

Mechanisms of Piperacillin/Tazobactam Nephrotoxicity: Piperacillin/Tazobactam-Induced Direct Tubular Damage in Mice

Piperacillin/tazobactam (PT) is one of the most commonly prescribed antibiotics for critically ill patients in intensive care. PT has been reported to cause direct nephrotoxicity; however, the underlying mechanisms remain unknown. We investigated the mechanisms underlying PT nephrotoxicity using a mouse model. The kidneys and sera were collected 24 h after PT injection. Serum blood urea nitrogen (BUN), creatinine, neutrophil gelatinase-associated lipocalin (NGAL), and renal pathologies, including inflammation, oxidative stress, mitochondrial damage, and apoptosis, were examined. Serum BUN, creatinine, and NGAL levels significantly increased in PT-treated mice. We observed increased IGFBP7, KIM-1, and NGAL expression in kidney tubules. Markers of oxidative stress, including 8-OHdG and superoxide dismutase, also showed a significant increase, accompanied by mitochondrial damage and apoptosis. The decrease in the acyl-coA oxidase 2 and Bcl2/Bax ratio also supports that PT induces mitochondrial injury. An in vitro study using HK-2 cells also demonstrated mitochondrial membrane potential loss, indicating that PT induces mitochondrial damage. PT appears to exert direct nephrotoxicity, which is associated with oxidative stress and mitochondrial damage in the kidney tubular cells. Given that PT alone or in combination with vancomycin is the most commonly prescribed antibiotic in patients at high risk of acute kidney injury, caution should be exercised.

Impact of Vancomycin Loading Doses and Dose Escalation on Glomerular Function and Kidney Injury Biomarkers in a Translational Rat Model

Vancomycin-induced kidney injury is common, and outcomes in humans are well predicted by animal models. This study employed our translational rat model to investigate temporal changes in the glomerular filtration rate (GFR) and correlations with kidney injury biomarkers related to various vancomycin dosing strategies. First, Sprague-Dawley rats received allometrically scaled loading doses or standard doses. Rats that received a loading dose had low GFRs and increased urinary injury biomarkers (kidney injury molecule 1 [KIM-1] and clusterin) that persisted through day 2 compared to those that did not receive a loading dose. Second, we compared low and high allometrically scaled vancomycin doses to a positive acute kidney injury control of high-dose folic acid. Rats in both the low- and high-dose vancomycin groups had higher GFRs on all dosing days than the positive-control group. When the two vancomycin groups were compared, rats that received the low dose had significantly higher GFRs on days 1, 2, and 4. Compared to low-dose vancomycin, the KIM-1 was elevated among rats in the high-dose group on dosing day 3. The GFR correlated most closely with the urinary injury biomarker KIM-1 on all experimental days. Vancomycin loading doses were associated with significant losses of kidney function and elevations of urinary injury biomarkers. In our translational rat model, both the degree of kidney function decline and urinary biomarker increases corresponded to the magnitude of the vancomycin dose (i.e., a higher dose resulted in worse outcomes).

Acute Kidney Injury in Patients with Liver Disease

AKI is commonly encountered in patients with decompensated cirrhosis, and it is associated with unfavorable outcomes. Among factors specific to cirrhosis, hepatorenal syndrome type 1, also referred to as hepatorenal syndrome-AKI, is the most salient and unique etiology. Patients with cirrhosis are vulnerable to traditional causes of AKI, such as prerenal azotemia, acute tubular injury, and acute interstitial nephritis. In addition, other less common etiologies of AKI specifically related to chronic liver disease should be considered, including abdominal compartment syndrome, cardiorenal processes linked to cirrhotic cardiomyopathy and portopulmonary hypertension, and cholemic nephropathy. Furthermore, certain types of GN can cause AKI in cirrhosis, such as IgA nephropathy or viral hepatitis related. Therefore, a comprehensive diagnostic approach is needed to evaluate patients with cirrhosis presenting with AKI. Management should be tailored to the specific underlying etiology. Albumin-based volume resuscitation is recommended in prerenal AKI. Acute tubular injury and acute interstitial nephritis are managed with supportive care, withdrawal of the offending agent, and, potentially, corticosteroids in acute interstitial nephritis. Short of liver transplantation, vasoconstrictor therapy is the primary treatment for hepatorenal syndrome type 1. Timing of initiation of vasoconstrictors, the rise in mean arterial pressure, and the degree of cholestasis are among the factors that determine vasoconstrictor responsiveness. Large-volume paracentesis and diuretics are indicated to relieve intra-abdominal hypertension and renal vein congestion. Direct-acting antivirals with or without immunosuppression are used to treat hepatitis B/C-associated GN. In summary, AKI in cirrhosis requires careful consideration of multiple potentially pathogenic factors and the implementation of targeted therapeutic interventions.

Pathophysiology of Acute Kidney Injury in Critical Illness: A Narrative Review

Acute kidney injury (AKI) is a syndrome that entails a rapid decline in kidney function with or without injury. The consequences of AKI among acutely ill patients are dire and lead to higher mortality, morbidity, and healthcare cost. To prevent AKI and its short and long-term repercussions, understanding its pathophysiology is essential. Depending on the baseline kidney histology and function reserves, the number of kidney insults, and the intensity of each insult, the clinical presentation of AKI may differ. While many factors are capable of inducing renal injury, they can be categorized into a few processes. The three primary processes reported in the literature are hemodynamic changes, inflammatory reactions, and nephrotoxicity. The majority of patients with AKI will suffer from more than one during their development and/or progression of AKI. Moreover, the development of one usually leads to the instigation of another. Thus, the interactions and progression between these mechanisms may determine the severity and duration of the AKI. Other factors such as organ crosstalk and how our concurrent therapies interact with these mechanisms complicate the pathophysiology of the progression of the AKI even further. In this narrative review article, we describe these three main pathophysiological processes that lead to the development and progression of AKI. © 2022 American Physiological Society. Compr Physiol 12: 1-14, 2022.

Association of vancomycin plus piperacillin-tazobactam with early changes in creatinine versus cystatin C in critically ill adults: a prospective cohort study

PURPOSE

Although dozens of studies have associated vancomycin + piperacillin-tazobactam with increased acute kidney injury (AKI) risk, it is unclear whether the association represents true injury or a pseudotoxicity characterized by isolated effects on creatinine secretion. We tested this hypothesis by contrasting changes in creatinine concentration after antibiotic initiation with changes in cystatin C concentration, a kidney biomarker unaffected by tubular secretion.

METHODS

We included patients enrolled in the Molecular Epidemiology of SepsiS in the ICU (MESSI) prospective cohort who were treated for ≥ 48 h with vancomycin + piperacillin-tazobactam or vancomycin + cefepime. Kidney function biomarkers [creatinine, cystatin C, and blood urea nitrogen (BUN)] were measured before antibiotic treatment and at day two after initiation. Creatinine-defined AKI and dialysis were examined through day-14, and mortality through day-30. Inverse probability of treatment weighting was used to adjust for confounding. Multiple imputation was used to impute missing baseline covariates.

RESULTS

The study included 739 patients (vancomycin + piperacillin-tazobactam n = 297, vancomycin + cefepime n = 442), of whom 192 had cystatin C measurements. Vancomycin + piperacillin-tazobactam was associated with a higher percentage increase of creatinine at day-two 8.04% (95% CI 1.21, 15.34) and higher incidence of creatinine-defined AKI: rate ratio (RR) 1.34 (95% CI 1.01, 1.78). In contrast, vancomycin + piperacillin-tazobactam was not associated with change in alternative biomarkers: cystatin C: - 5.63% (95% CI - 18.19, 8.86); BUN: - 4.51% (95% CI - 12.83, 4.59); or clinical outcomes: dialysis: RR 0.63 (95% CI 0.31, 1.29); mortality: RR 1.05 (95%CI 0.79, 1.41).

CONCLUSIONS

Vancomycin + piperacillin-tazobactam was associated with creatinine-defined AKI, but not changes in alternative kidney biomarkers, dialysis, or mortality, supporting the hypothesis that vancomycin + piperacillin-tazobactam effects on creatinine represent pseudotoxicity.

Blood Biomarkers and Metabolomic Profiling for the Early Diagnosis of Vancomycin-Associated Acute Kidney Injury: A Systematic Review and Meta-Analysis of Experimental Studies

Background: several blood-based biomarkers have been proposed for predicting vancomycin-associated kidney injury (VIKI). However, no systematic analysis has compared their prognostic value. Objective: this systematic review and meta-analysis was designed to investigate the role of blood biomarkers and metabolomic profiling as diagnostic and prognostic predictors in pre-clinical studies of VIKI. Methods: a systematic search of PubMed was conducted for relevant articles from January 2000 to May 2022. Animal studies that administered vancomycin and studied VIKI were eligible for inclusion. Clinical studies, reviews, and non-English literature were excluded. The primary outcome was to investigate the relationship between the extent of VIKI as measured by blood biomarkers and metabolomic profiling. Risk of bias was assessed with the CAMARADES checklist the SYRCLE’s risk of bias tool. Standard meta-analysis methods (random-effects models) were used. Results: there were four studies for the same species, dosage, duration of vancomycin administration and measurement only for serum creatine and blood urea nitrogen in rats. A statistically significant increase was observed between serum creatinine in the vancomycin group compared to controls (pooled p = 0.037; Standardized Mean Difference: 2.93; 95% CI: 0.17 to 5.69; I² = 92.11%). Serum BUN levels were not significantly different between control and vancomycin groups (pooled p = 0.11; SMD: 3.05; 95% CI: 0.69 to 6.8; I² = 94.84%). We did not identify experimental studies using metabolomic analyses in animals with VIKI. Conclusions: a total of four studies in rodents only described outcomes of kidney injury as defined by blood biomarkers. Blood biomarkers represented included serum creatinine and BUN. Novel blood biomarkers have not been explored.

Piperacillin–Tazobactam Plus Vancomycin-Associated Acute Kidney Injury in Adults: Can Teicoplanin or Other Antipseudomonal Beta-Lactams Be Remedies?

Numerous observational studies and meta-analyses have suggested that combination therapy consisting of piperacillin–tazobactam (TZP) and vancomycin (VAN) augments acute kidney injury (AKI) risk when compared to viable alternatives, such as cefepime–vancomycin (FEP–VAN) and meropenem–VAN. However, the exact pathophysiological mechanisms of this phenomenon are still unclear. One major limitation of the existing studies is the utilization of serum creatinine to quantify AKI since serum creatinine is not a sufficiently sensitive and specific biomarker to truly define the causal relationship between TZP–VAN exposure and nephrotoxicity. Even so, some preventive measures can be taken to reduce the risk of AKI when TZP–VAN is preferred. These measures include limiting the administration of TZP–VAN to 72 h, choosing FEP–VAN in place of TZP–VAN in appropriate cases, monitoring the VAN area under the curve level rather than the VAN trough level, avoiding exposure to other nephrotoxic agents, and minimizing the prescription of TZP–VAN for patients with a high risk of AKI. More data are needed to comment on the beneficial impact of the extended-infusion regimen of TZP on nephrotoxicity. Additionally, TZP and teicoplanin can be reasonable alternatives to TZP–VAN for the purpose of lowering AKI risk. However, the data are scarce to advocate this practice convincingly.

Mapping Adverse Outcome Pathways for Kidney Injury as a Basis for the Development of Mechanism-Based Animal-Sparing Approaches to Assessment of Nephrotoxicity

In line with recent OECD activities on the use of AOPs in developing Integrated Approaches to Testing and Assessment (IATAs), it is expected that systematic mapping of AOPs leading to systemic toxicity may provide a mechanistic framework for the development and implementation of mechanism-based in vitro endpoints. These may form part of an integrated testing strategy to reduce the need for repeated dose toxicity studies. Focusing on kidney and in particular the proximal tubule epithelium as a key target site of chemical-induced injury, the overall aim of this work is to contribute to building a network of AOPs leading to nephrotoxicity. Current mechanistic understanding of kidney injury initiated by 1) inhibition of mitochondrial DNA polymerase γ (mtDNA Polγ), 2) receptor mediated endocytosis and lysosomal overload, and 3) covalent protein binding, which all present fairly well established, common mechanisms by which certain chemicals or drugs may cause nephrotoxicity, is presented and systematically captured in a formal description of AOPs in line with the OECD AOP development programme and in accordance with the harmonized terminology provided by the Collaborative Adverse Outcome Pathway Wiki. The relative level of confidence in the established AOPs is assessed based on evolved Bradford-Hill weight of evidence considerations of biological plausibility, essentiality and empirical support (temporal and dose-response concordance).

Therapeutic Effect of Teneligliptin in Drug-Induced Nephrotoxicity: An In-Vitro Study

Background

Drug-induced nephrotoxicity is an important side effect of many commonly used drugs. In this study, we planned to evaluate the effects of teneligliptin (TG), which is a dipeptidyl peptidase-4 (DPP-4) inhibitor, on cell healing by creating nephrotoxicity models in human renal proximal tubule cell and human embryonic kidney epithelial cells cell lines in-vitro with cisplatin, vancomycin, and gentamicin.

Methodology

First, we determined the 50% inhibitory concentration doses of nephrotoxic drugs and the nephroprotective dose of TG. Then, we analyzed the difference in cell viability, apoptosis, and oxidative stress (reactive oxygen and nitrogen species (ROS/RNS) production) between TG-treated and untreated cells after nephrotoxicity occurred. Moreover, we evaluated the expression of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in cells.

Results

We found that when cell lines were treated after toxicity was induced with TG, cell viability increased, apoptosis and ROS/RNS production were significantly decreased, and expressions of KIM-1 and NGAL were significantly reduced.

Conclusions

This study showed that TG has positive effects on the recovery of drug-induced nephrotoxicity in an in-vitro setting.

Drug-Induced Acute Kidney Injury

Medications are a common cause of AKI especially for patients admitted to hospital wards and the intensive care unit. Although drug-related kidney injury occurs through different mechanisms, this review will focus on three specific types of tubulointerstitial injury. Direct acute tubular injury develops from several medications, which are toxic to various cellular functions. Their excretory pathways through the proximal tubules contribute further to AKI. Drug-induced AKI may also develop through induction of inflammation within the tubulointerstitium. Medications can elicit a T cell-mediated immune response that promotes the development of acute interstitial nephritis leading to AKI. Although less common, a third pathway to kidney injury results from the insolubility of drugs in the urine leading to their precipitation as crystals within distal tubular lumens, causing a crystalline-related AKI. Intratubular obstruction, direct tubular injury, and localized inflammation lead to AKI. Clinicians should be familiar with the pathogenesis and clinical-pathologic manifestations of these forms of kidney injury. Prevention and treatment of AKI relies on understanding the pathogenesis and judiciously using these agents in settings where AKI risk is high.

Pathological Features of Recovery or Progression in Acute Tubular Necrosis: Single Centre Study

Acute tubular necrosis (ATN) is the most important and frequent cause of acute kidney injury (AKI). Controversy exists concerning the role of renal biopsy in the evaluation of ATN prognosis. We aim in our study to evaluate the role of renal biopsy for the detection of recovery and progression and rate of recovery of ATN. The study was designed to include all biopsies with the diagnosis in ATN in adults >21-year-old, from January 2016 to December 2018. Biopsies were recruited retrospectively and were reviewed by three pathologists and quantitated. Four histological ATN features were evaluated. Flattening cells, distension or dilatation, debris, and vacuolation and for each a score were attributed as follows: 0 = less than 5% of section, 1 = 6%-25%, 2 = 26%-50%, 3 = >50%. Thirty-five patients with 35 renal biopsies were analyzed. Flattening was seen <5% in nine patients, 6%-25% in 15 patients, 26%-50% in six patients. and >50% in five patients. Dilatation was seen <5% in 11 patient, 6%-25% in 10 patients, 26%-50% seen in six patients, and >50% in eight patients. The presence of debris was seen in <5% in 12 patients, 6%-25% in 12 patients, 26%-50% seen in six patients, and >50% seen in five patient. Vacuolation was seen in 5% in eight patients, 6%-25% in 14 patients, 26%-50% in seven patients, and >50% in six patients. It was found that flattening <5% and dilatation <5% and dilatation >50% in renal biopsy are the good indicators for recovery and good prognosis of cases of ATN, in addition debris <5% and >50% and vacuolation <5% are also good indicators for recovery and good prognosis of cases of ATN. On the other hand, flattening from 6% to 25% and from 26% to 50%, dilatation from 6% to 25%, debris from 26% to 50% and vacuolation >50% are also indicators for delayed recovery and poor prognosis of cases of ATN. Renal biopsy in AKI with the diagnosis of ATN with scoring system of flattening, dilatation, debris, and vacuolation can point to indication of recovery or progression of these cases.

Trimetazidine an emerging paradigm in renal therapeutics: Preclinical and clinical insights

Trimetazidine (TMZ) is a well-known anti-ischemic agent used for the treatment of angina pectoris. In the past decades, the efficacy of this drug has been tested in a wide range of kidney injuries, including drug-induced nephrotoxicity (DIN), radio-contrast agent-induced nephropathy, and surgically induced renal ischemic injury. TMZhas renoprotective effects by attenuating oxidative stress, inflammatory cytokine release, maintaining oxygen and energy balance. Moreover, TMZ administration prevented kidney graft rejection in the porcine model by suppressing the infiltration of mononuclear cells, preserving mitochondrial functions, and maintaining Ca+ homeostasis. In DIN and diabetic kidney diseases,TMZ treatment prevents renal injury by inactivating immune cells, attenuating renal fibrosis, inflammation, apoptosis, and histological abnormalities. Interestingly, the clinical therapeutic efficacy of TMZ has also been documented in pre-existing kidney disease patients undergoing contrast exposure for diagnostic intervention. However, the mechanistic insights into the TMZ mediated renoprotective effects in other forms of renal injuries, including type-2 diabetes, drug-induced nephrotoxicity, and hypertension-induced chronic kidney diseases, remain uninvestigated and incomplete. Moreover, the clinical utility of TMZ as a renoprotective agent in radio-contrast-induced nephrotoxicity needs to be tested in a large patient population. Nevertheless, the available pieces of evidence suggest that TMZ is a promising and emerging renal therapy for the treatment and management of kidney diseases of variable etiologies. This review discusses the various pre-clinical and clinical findings and provides mechanistic insights into the TMZ mediated beneficial effects in various kidney diseases.

Vancomycin Nephrotoxicity Causing Renal Transplant Acute Kidney Injury

Nephrotoxicity is a rather frequent side effect of vancomycin treatment. Attributes of vancomycin nephrotoxicity (VN) are well documented, including its clinical manifestations and renal morphologic changes. However, VN has not been emphasized as the cause of acute kidney injury (AKI) in the renal transplant setting. We report the first 3 such cases. In each of these cases, AKI developed concurrently with vancomycin treatment and resolved after its cessation. As compared with the general population, VN in the renal transplant setting displayed some unusual clinical behaviors. Its development was rather capricious, being noted in some but not every episode of vancomycin treatment, even in the same individual. AKI developed gradually in conjunction with protracted vancomycin treatment, in contrast to a precipitous course in the nontransplant setting. However, renal transplant biopsies showed typical features of VN in each case. VN is an unusual but now well-documented cause of AKI in renal transplant recipients. VN in this setting may display some atypical features, setting it apart from that in the general population. However, renal transplant biopsy changes are characteristic and are amenable to a definitive diagnosis.

Impact of ascorbic acid in reducing the incidence of vancomycin associated nephrotoxicity in critically ill patients: A preliminary randomized controlled trial

Background Antioxidants show nephroprotective effect against vancomycin associated nephrotoxicity (VAN) in animals. This study aimed to assess the ascorbic acid nephro-protective role against VAN clinically.

Methods Forty-one critically ill patients were randomly assigned to one of two groups: intervention group (vancomycin IV plus ascorbic acid, n=21) or control group (vancomycin IV only, n=20). Primary outcomes were the incidence of VAN and the absolute change in creatinine parameters, while mortality rate was the secondary outcome. Nephrotoxicity was defined as an increase in serum creatinine (S.cr) by at least 0.5 mg/dL or 50% of baseline for at least two successive measurements. This study is registered at Clinicaltrials.gov (NCT03921099), April 2019.

Results Mean absolute S.cr increase was significant when compared between both groups, P-value = 0.036, where S.cr increased by 0.05(0.12) and 0.34(0.55) mg/dL in the intervention and control groups, respectively. Mean absolute Cr.cl decline was significant when compared between both groups, P-value = 0.04, where Cr.cl was decreased by 5.9(17.8) and 22.3(30.4) ml/min in the intervention and control groups, respectively. Incidence of VAN was 1/21(4.7%) versus 5/20(25%) in the intervention and control groups, respectively (RR: 0.19; CI: 0.024–1.49; P-value = 0.093). Mortality was higher in the control group; however, it was not statistically significant, P-value = 0.141.

Conclusion Co-administration of ascorbic acid with vancomycin preserved renal function and reduced the absolute risk of VAN by 20.3%, however, the reduction in VAN incidence didn’t reach statistical significance level. Further large multicenter prospective trials are recommended.

Changes of renal transporters in the kinetic process of VCM-induced nephrotoxicity in mice

Renal transporters involved in tubular excretion pathway are considered to be the key concern in drug evaluations in nephrotoxicity. However, the relationship between the alternation of renal transporters and the kinetic process of vancomycin (VCM)-induced nephrotoxicity has not been fully elucidated. The present study investigated the alteration of renal transporters expression in the kinetic process of VCM-induced nephrotoxicity in mice. C57BL/6 mice were administrated with normal saline or VCM for 7 days. Biochemical and pathological analyses were conducted to investigate the nephrotoxicity induced by VCM administration. Renal oxidative status, plasma, and kidney content of VCM were monitored. Quantitative real-time polymerase chain reaction and immunohistochemistry analyses were performed to analyze the expression of renal transporters. Finally, our data showed that the exposure of VCM (400 mg/kg) caused a slight nephrotoxicity in mice, whereas exposure of VCM (600 mg/kg) resulted in the severe nephrotoxicity in mice as evidenced by biochemical parameters and renal morphological changes. In addition, the accumulation of VCM in kidney is higher than plasma. Interestingly, VCM (600 mg/kg, body weight) resulted in the induction of Oct2-Mate1 and Oat1/3-Mrp2/Mrp4/Bcrp pathways. However, VCM (400 mg/kg, body weight) caused the induction of Oct2-Mate1/Mate2 and Oat1/3-Mrp4/Bcrp pathways. The changes of renal transporters in association with the kinetic process of VCM-induced nephrotoxicity may exert important practical implications for its optimal use in clinic.

Nomenclature and diagnostic criteria for acute kidney injury - 2020 consensus of the Taiwan AKI-task force

Acute kidney injury (AKI) is a common syndrome that has a significant impact on prognosis in various clinical settings. To evaluate whether new evidence supports changing the current definition/classification/staging systems for AKI suggested by the Kidney Disease: Improving Global Outcomes (KDIGO) 2012 Clinical Practice Guideline, the Taiwan AKI-TASK Force, composed of 64 experts in various disciplines, systematically reviewed the literature and proposed recommendations about the current nomenclature and diagnostic criteria for AKI. The Taiwan Acute Kidney Injury (TW-AKI) Consensus 2020 was established following the principles of evidence-based medicine to investigate topics covered in AKI guidelines. The Taiwan AKI-TASK Force determined that patients with AKI have a higher risk of developing chronic kidney disease, end-stage renal disease, and death. After a comprehensive review, the TASK Force recommended using novel biomarkers, imaging examinations, renal biopsy, and body fluid assessment in the diagnosis of AKI. Clinical issues with regards to the definitions of baseline serum creatinine (sCr) level and renal recovery, as well as the use of biomarkers to predict renal recovery are also discussed in this consensus. Although the present classification systems using sCr and urine output for the diagnosis of AKI are not perfect, there is not enough evidence to change the current criteria in clinical practice. Future research should investigate and clarify the roles of the aforementioned tools in clinical practice for AKI.

Attributable nephrotoxicity of vancomycin in critically ill patients: a marginal structural model study

BACKGROUND

Although vancomycin nephrotoxicity is recognizable, critically ill patients have other potential reasons for acute kidney injury (AKI) and determining its attributable nephrotoxic risk in this population can be cumbersome.

OBJECTIVES

To determine the risk of AKI attributable to vancomycin, controlling for baseline and time-dependent confounders.

METHODS

Time-fixed and daily time-varying variables were extracted from a large public database. The exposures analysed were: (i) IV vancomycin; (ii) serum trough level greater than 15 and 20 mg/L; and (iii) concomitant exposure to vancomycin and piperacillin/tazobactam or other antipseudomonal β-lactams. Censoring and exposure inverse probability of treatment weighting were calculated. Marginal structural models were plotted to evaluate AKI, severe AKI (stage 2/3) and need of renal replacement therapy (RRT).

RESULTS

A total of 26 865 patients were included; 19.7% received vancomycin during ICU stay. After adjusting for fixed and time-variable confounders, vancomycin exposure was associated with AKI (HR = 1.24, 95% CI = 1.09-1.38), but not with severe AKI or need of RRT (HR = 1.05, 95% CI = 0.91-1.23 and HR = 0.97, 95% CI = 0.74-1.29, respectively). A serum trough level greater than 20 mg/L was associated with AKI (HR = 1.90, 95% CI = 1.52-2.30) and severe AKI (HR = 1.69, 95% CI = 1.31-2.19), but showed no statistically significant association with need of RRT (HR = 1.48, 95% CI = 0.92-2.56). The vancomycin + piperacillin/tazobactam combination was not associated with a greater risk than vancomycin alone.

CONCLUSIONS

The attributable nephrotoxicity of vancomycin in critically ill patients is significantly lower than previously suggested and severe AKI is related to vancomycin only when trough serum levels are greater than 20 mg/L.

Lack of synergistic nephrotoxicity between vancomycin and piperacillin/tazobactam in a rat model and a confirmatory cellular model

BACKGROUND

Vancomycin and piperacillin/tazobactam are reported in clinical studies to increase acute kidney injury (AKI). However, no clinical study has demonstrated synergistic toxicity, only that serum creatinine increases.

OBJECTIVES

To clarify the potential for synergistic toxicity between vancomycin, piperacillin/tazobactam and vancomycin + piperacillin/tazobactam treatments by quantifying kidney injury in a translational rat model of AKI and using cell studies.

METHODS

(i) Male Sprague-Dawley rats (n = 32) received saline, vancomycin 150 mg/kg/day intravenously, piperacillin/tazobactam 1400 mg/kg/day intraperitoneally or vancomycin + piperacillin/tazobactam for 3 days. Urinary biomarkers and histopathology were analysed. (ii) Cellular injury was assessed in NRK-52E cells using alamarBlue®.

RESULTS

Urinary output increased from Day -1 to Day 1 with vancomycin but only after Day 2 for vancomycin + piperacillin/tazobactam-treated rats. Plasma creatinine was elevated from baseline with vancomycin by Day 2 and only by Day 4 for vancomycin + piperacillin/tazobactam. Urinary KIM-1 and clusterin were increased with vancomycin from Day 1 versus controls (P < 0.001) and only on Day 3 with vancomycin + piperacillin/tazobactam (P < 0.001, KIM-1; P < 0.05, clusterin). The histopathology injury score was elevated only in the vancomycin group when compared with piperacillin/tazobactam as a control (P = 0.04) and generally not so with vancomycin + piperacillin/tazobactam. In NRK-52E cells, vancomycin induced cell death with high doses (IC50 48.76 mg/mL) but piperacillin/tazobactam did not, and vancomycin + piperacillin/tazobactam was similar to vancomycin.

CONCLUSIONS

All groups treated with vancomycin demonstrated AKI; however, vancomycin + piperacillin/tazobactam was not worse than vancomycin. Histopathology suggested that piperacillin/tazobactam did not worsen vancomycin-induced AKI and may even be protective.

Acute Kidney Injury in the Modern Era of Allogeneic Hematopoietic Stem Cell Transplantation

Background and objectives Acute kidney injury (AKI) is a major complication of allogeneic hematopoietic stem cell transplantation, increasing risk of non-relapse mortality. AKI etiology is often ambiguous due to heterogeneity of conditioning/graft-versus-host disease (GVHD) regimens. To date, GVHD and calcineurin inhibitor effects on AKI are not well defined. We aimed to describe AKI and assess pre/post-hematopoietic transplant risk factors in a large recent cohort. Design, setting, participants, and measurements We performed a single-center retrospective study of 616 allogeneic hematopoietic cell transplant recipients from 2014-2017. We defined AKI and CKD based on KDIGO criteria and estimated GFR using CKD-EPI equation. We assessed AKI pre/post-hematopoietic transplant risk factors using cause-specific Cox regression and association of AKI with CKD outcomes using Chi-squared test. AKI was treated as a time-dependent variable in relation to non-relapse mortality. Results Incidence of AKI by day-100 was 64%. Exposure to tacrolimus and other nephrotoxins conferred a higher risk of AKI, but tacrolimus levels were not associated with severity. Reduced intensity conditioning carried higher AKI risk compared to myeloablative conditioning. Most stage 3 AKIs were due to ischemic acute tubular necrosis and CNI nephrotoxicity. Kidney replacement therapy was initiated in 21/616 (3%) of whom 9/21 (43%) recovered and 5/21 (24%) survived to hospital discharge. T-cell depleted transplants, higher baseline albumin, and non-Hispanic ethnicity were associated with lower risk of AKI. CKD developed in 21% (73/345) of patients after 12 months. Non-relapse mortality was higher in those with AKI (HR 2.77, 95% CI: 1.8-4.27). Conclusions AKI post-hematopoietic cell transplant remains a major concern. Risk of AKI was higher with exposure to CNIs. T cell depleted hematopoietic cell transplants and higher albumin had lower risk of AKI. Forty-three percent of patients requiring KRT recovered kidney function. Prospective studies are needed to further assess modification of these risk factors.

The Mechanism of Drug Nephrotoxicity and the Methods for Preventing Kidney Damage

Acute kidney injury (AKI) is a global health challenge of vast proportions, as approx. 13.3% of people worldwide are affected annually. The pathophysiology of AKI is very complex, but its main causes are sepsis, ischemia, and nephrotoxicity. Nephrotoxicity is mainly associated with the use of drugs. Drug-induced AKI accounts for 19-26% of all hospitalized cases. Drug-induced nephrotoxicity develops according to one of the three mechanisms: (1) proximal tubular injury and acute tubular necrosis (ATN) (a dose-dependent mechanism), where the cause is related to apical contact with drugs or their metabolites, the transport of drugs and their metabolites from the apical surface, and the secretion of drugs from the basolateral surface into the tubular lumen; (2) tubular obstruction by crystals or casts containing drugs and their metabolites (a dose-dependent mechanism); (3) interstitial nephritis induced by drugs and their metabolites (a dose-independent mechanism). In this article, the mechanisms of the individual types of injury will be described. Specific groups of drugs will be linked to specific injuries. Additionally, the risk factors for the development of AKI and the methods for preventing and/or treating the condition will be discussed.

Vancomycin-Associated Tubular Casts and Vancomycin Nephrotoxicity

Introduction

Vancomycin nephrotoxicity is frequent and may be due to drug-induced acute tubular necrosis (ATN) or tubulointerstitial nephritis (TIN). Vancomycin-associated tubular cast (VTC) was recently described and may represent a novel cause of vancomycin nephrotoxicity. However, much is still unknown about VTC.

Materials and Methods

Thirty-seven kidney biopsy specimens from patients who were treated with vancomycin and developed acute kidney injury (AKI) were found among a total of 4673 biopsy samples between 2010 and 2019. These biopsy specimens were subjected to light microscopy, immunofluorescence, electron microscopy, and immunolocalization for vancomycin, uromodulin, myoglobin, tubular segment–specific markers, and examined for VTCs. The findings were correlated with the clinical course.

Results

VTCs displayed precipitated vancomycin casts in a background of uromodulin; the casts were limited to the distal tubules, and always associated with a background of more diffuse renal injury (ATN or TIN). The diagnosis of vancomycin nephrotoxicity was made in in 28 of 37 patients. VTC was noted in 25 of 28 biopsy samples from patients diagnosed with vancomycin nephrotoxicity and in one of nine biopsy samples from patients without this diagnosis. Vancomycin nephrotoxicity was diagnosed in 25 of 26 patients whose biopsy specimens showed VTC, but in only 3 of 11 patients without VTC in the biopsy samples.

Conclusions

VTC displays a characteristic morphologic profile amenable to ready recognition in biopsy specimens. It results from coprecipitation of vancomycin and uromodulin. It facilitates the biopsy diagnosis of vancomycin nephrotoxicity. It may have a nephrotoxic effect superimposing on and independent from the ATN or interstitial nephritis in the pathogenesis of vancomycin nephrotoxicity.

Nephrotoxicity from Vancomycin Combined with Piperacillin-Tazobactam: A Comprehensive Review

BACKGROUND

Recent studies have identified the combination of vancomycin with piperacillin-tazobactam (VPT) to be associated with increased nephrotoxicity. Multiple, large cohort studies have found this widely used combination to have a higher risk of nephrotoxicity than other regimens in a variety of populations.

SUMMARY

This review summarizes the epidemiology and clinical features of VPT-associated acute kidney injury (AKI). Potential mechanisms involved in the pathogenesis of this phenomenon are also discussed. Key Message: VPT-associated nephrotoxicity is a recently recognized clinical entity. Clinical strategies to minimize the risk of toxicity in this setting include antimicrobial stewardship, monitoring of kidney function, and emerging data supporting the potential role for novel biomarkers in predicting and managing AKI.

Kidney biopsy findings in vancomycin-induced acute kidney injury: a pooled analysis

BACKGROUND

Acute kidney injury represents a major adverse effect of vancomycin administration. The aim of the present study is to accumulate all biopsy-proven cases of vancomycin nephrotoxicity and assess the association of histopathological features with renal prognosis.

METHODS

Medline, Scopus, CENTRAL, Web of Science, and Clinicaltrials.gov were systematically searched from inception to 29 September 2020. All case reports/series providing individual data of patients with biopsy-proven vancomycin nephrotoxicity were held eligible. A time-to-event analysis was performed evaluating the effects of histological diagnosis on renal recovery.

RESULTS

Overall, 18 studies were included, comprising 21 patients. Acute tubulointerstitial nephritis was the predominant pattern in 9 patients and was associated with a significantly higher risk of permanent renal dysfunction (HR: 5.08, 95% CI: [1.05-24.50)] compared to acute tubular necrosis. Tubulitis and eosinophilic infiltration were the most common histopathological findings, while interstitial fibrosis was linked to significantly worse renal prognosis (HR: 5.55, 95% CI: 1.13-27.27). Immunofluorescence and electron microscopy features were non-specific. Obstruction by tubular casts composed of vancomycin aggregates and uromodulin has been identified as a new mechanism of nephrotoxicity.

CONCLUSIONS

Acute tubular necrosis and tubulointerstitial nephritis represent the main histological patterns of vancomycin-induced acute kidney injury. The presence of fibrosis in the context of interstitial inflammation may be linked to lower recovery rates and worse long-term renal outcomes. A novel cast nephropathy obstructive mechanism has been suggested, necessitating further confirmation. Large-scale studies should define the exact indications of kidney biopsy in cases with suspected vancomycin nephrotoxicity.

Utilization of potentially inappropriate medication and risk of adverse drug events among older adults with chronic renal insufficiency: a population-wide cohort study

BACKGROUND

The use of potentially inappropriate medication (PIM) in population of older adults may result in adverse drug events (ADE) already after short term exposure, especially when it is prescribed to patients with chronic kidney disease (CKD). In order to limit ADE in the treatment of older adults PIM lists have been constructed as a source of information for healthcare professionals. The aim of this study was to estimate the utilization of PIM and incidence of ADE in older adults (≥70 years) with CKD.

METHODS

We conducted a retrospective population-wide cohort study including patients from Lower Austria who were 70 years or older and diagnosed with CKD in the period from 2008 to 2011. Utilization of PIM was estimated from prescriptions filled by target population. We estimated risks of hospitalization due to ADE within 30 days after incident PIM prescription and compared them to a PIM-free control group by using marginal structural models (MSM).

RESULTS

We identified 11,547 patients (women: 50.6%, median age in 2008: 78 years) who fulfilled the inclusion criteria. In total 24.7 and 8.1% of all prescriptions from that period contained a medication with a substance listed in the EU (7)-PIM and AT-PIM list, respectively. Proton pump inhibitors and Ginkgo biloba were the most often prescribed PIMs in this population. 94.6 and 79.3% patients filled at least one EU(7)-PIM and AT-PIM prescription, respectively. Despite the relatively high utilization of PIM there was only a low incidence of clinically relevant ADE. No event type exceeded the threshold level of 1% in the analysis of risks of ADE after filling a prescription for PIM. Nevertheless, MSM analysis showed an increased risk for 11 drugs and reduced risk for 4 drugs.

CONCLUSIONS

PIM prescription was common among older adults with CKD, however, only a small number of these drugs eventually led to hospitalization due to ADE within 30 days after incident PIM was filled. In the absence of a clinically important PIM-related increase in risk, an assessment of potential ADE severity to a PIM list by using a warning score system seems prudent.

The efficiency of pomegranate (Punica granatum) peel ethanolic extract in attenuating the vancomycin-triggered liver and kidney tissues injury in rats

This study evaluated the potential of Punica granatum peel ethanol extract (PPEE) in attenuating the liver and kidney tissue injury induced by vancomycin (VM) treatment in rats. Fifty rats were distributed equally into five groups: control group, PPEE-administered group (100 mg/kg BW/day for 2 weeks; orally), VM-treated group (443.6 mg/kg BW, every alternate day for 2 weeks; intraperitoneally), pre-treated group, and concomitant-treated group. The biochemical response and the histopathology of the hepatic and renal tissue of the treated animals were assessed. The results showed that VM treatment induced substantial hepatotoxicity and nephrotoxicity, evidenced by a significant elevation in tissue injury and lipid oxidative (malondialdehyde) and inflammatory response (C-reactive protein) biomarkers, with lowered antioxidants and protein levels. Additionally, VM treatment induced various morphological, cytotoxic, vascular, and inflammatory perturbations as well as upregulation in the immune-expression of Caspase-3 and downregulation of BCL-2. Moreover, PPEE co-treatment was found to reduce the VM-induced toxicity by protecting the tissue against reactive oxygen species (ROS)-mediated oxidative damage, and inflammation as well as hinder the apoptotic cell death by modulating the expression of apoptosis-related proteins. Thus, we conclude that the PPEE administration showed more restoring efficacy when administered prior to VM medication.

[Therapeutics for acute tubular necrosis in 2020]

Acute kidney injury is a major cause of in-hospital morbidity and mortality because of the serious nature of the underlying illnesses and the high incidence of complications. The two major causes of acute kidney injury that occur in the hospital are prerenal disease and acute tubular necrosis. Acute tubular necrosis has a histological definition, even if a kidney biopsy is rarely performed. Kidney injuries occurring during acute tubular necrosis are underlined by different pathophysiological mechanisms that emphasize the role of hypoxia on the tubular cells such as apoptosis, cytoskeleton disruption, mitochondrial function and the inflammation mediated by innate immune cells. The microcirculation and the endothelial cells are also the targets of hypoxia-mediated impairment. Repair mechanisms are sometimes inadequate because of pro-fibrotic factors that will lead to chronic kidney disease. Despite all the potential therapeutic targets highlighted by the pathophysiological knowledge, further works remain necessary to find a way to prevent these injuries.

Renal Expression of Light Chain Binding Proteins

Overproduction of human light chains (LCs) and immunoglobulins can result in various forms of renal disease such as cast nephropathy, monoclonal immunoglobulin deposition disease, LC proximal tubulopathy, AL amyloidosis, and crystal storing histiocytosis. This is caused by cellular uptake of LCs and overwhelmed intracellular transport and degradation in patients with high urine LC concentrations. LC kappa and lambda purification was evaluated by sodium dodecyl sulfate gel electrophoresis. LC and myeloma protein binding to immobilized renal proteins was measured by enzyme-linked immunosorbent assay (ELISA). The human protein microarray (HuProt™) was screened with purified kappa and lambda LC. Identified LC partners were subsequently analyzed in silico for renal expression sites using protein databases, Human Protein Atlas, UniProt, and Bgee. Binding of urinary LCs and immunoglobulins to immobilized whole renal proteins from 22 patients with myeloma or plasma cell dyscrasia was shown by ELISA. Forty lambda and 23 kappa interaction partners were identified from HuProt™ array screens, of which 21 were shared interactors. Among the total of 42 interactors, 12 represented cell surface proteins. Lambda binding signals were approximately 40% higher than kappa signals. LC interaction with renal cells and disease-causing pathologies are more complex than previously thought. It involves an extended spectrum of proteins expressed throughout the nephron, and their identification has been enabled by recently developed methods of protein analysis such as protein microarray screening. Further biochemical studies on interacting proteins are warranted to elucidate their clinical relevance.

Perioperative Renoprotection: General Mechanisms and Treatment Approaches

In the perioperative setting, acute kidney injury (AKI) is a frequent complication, and AKI itself is associated with adverse outcomes such as higher risk of chronic kidney disease and mortality. Various risk factors are associated with perioperative AKI, and identifying them is crucial to early interventions addressing modifiable risk and increasing monitoring for nonmodifiable risk. Different mechanisms are involved in the development of postoperative AKI, frequently picturing a multifactorial etiology. For these reasons, no single renoprotective strategy will be effective for all surgical patients, and efforts have been attempted to prevent kidney injury in different ways. Some renoprotective strategies and treatments have proven to be useful, some are no longer recommended because they are ineffective or even harmful, and some strategies are still under investigation to identify the best timing, setting, and patients for whom they could be beneficial. With this review, we aim to provide an overview of recent findings from studies examining epidemiology, risk factors, and mechanisms of perioperative AKI, as well as different renoprotective strategies and treatments presented in the literature.

Electron microscopic findings can support multiple etiologies of nephrotoxicity in renal tubules

Electron microscopy (EM) has been mainly used for identifying ultrastructural abnormalities such as fusion of foot processes and immune complex deposits in glomeruli. However, electron microscopic findings in renal tubules can provide either diagnostic evidence (unique finding) or supportive evidence (additional finding) for final diagnosis. Here we present multiple situations that EM can be used for drawing conclusions of various drug-associated nephrotoxicity. Multiple cases with drug-induced nephrotoxicity are reviewed, including clinical history, EM findings, and serum creatinine (sCr) levels, prior to renal biopsy and during follow-up. Two cases with nephrotoxicity by aminoglycoside antibiotics showed acute tubular injury with EM findings of myeloid bodies, characterized by laminated dense materials in lysosomes in both proximal and distal tubular epithelium (diagnostic evidence). Five cases of vancomycin associated nephrotoxicity presented with acute tubular injury and vancomycin casts in distal tubules, characterized by central laminated casts in the lumina of distal tubules (supportive evidence). Vedolizumab, a humanized monoclonal antibody used in treating Crohn's disease, can cause T-cell dominant acute interstitial nephritis, with EM revealing lymphocytic infiltration into tubules as tubulitis (supportive evidence). Four of Seven cases (5/8) cases had renal functional recovery upon follow-up check for sCr. EM findings of characteristic changes in renal tubules can be particularly useful as either diagnostic or supportive evidence, in correlation with clinical history and etiologies of nephrotoxicity. Therefore, EM should not only focus on glomerular changes, but renal tubular changes as well.