The AMPK activator ATX-304 alters cellular metabolism to protect against cisplatin-induced acute kidney injury.

Acute kidney injury (AKI) disrupts energy metabolism. Targeting metabolism through AMP-activated protein kinase (AMPK) may alleviate AKI. ATX-304, a pan-AMPK activator, was evaluated in C57Bl/6 mice and tubular epithelial cell (TEC) cultures. Mice received ATX-304 (1 mg/g) or control chow for 7 days before cisplatin-induced AKI (CI-AKI). Primary cultures of tubular epithelial cells (TECs) were pre-treated with ATX-304 (20 µM, 4 h) prior to exposure to cisplatin (20 µM, 23 h). ATX-304 increased acetyl-CoA carboxylase phosphorylation, indicating AMPK activation. It protected against CI-AKI measured by serum creatinine (control 0.05 + 0.03 mM vs ATX-304 0.02 + 0.01 mM, P = 0.03), western blot for neutrophil gelatinase-associated lipocalin (NGAL) (control 3.3 + 1.8-fold vs ATX-304 1.2 + 0.55-fold, P = 0.002), and histological injury (control 3.5 + 0.59 vs ATX-304 2.7 + 0.74, P = 0.03). In TECs, pre-treatment with ATX-304 protected against cisplatin-mediated injury, as measured by lactate dehydrogenase release, MTS cell viability, and cleaved caspase 3 expression. ATX-304 protection against cisplatin was lost in AMPK-null murine embryonic fibroblasts. Metabolomic analysis in TECs revealed that ATX-304 (20 µM, 4 h) altered 66/126 metabolites, including fatty acids, tricarboxylic acid cycle metabolites, and amino acids. Metabolic studies of live cells using the XFe96 Seahorse analyzer revealed that ATX-304 increased the basal TEC oxygen consumption rate by 38%, whereas maximal respiration was unchanged. Thus, ATX-304 protects against cisplatin-mediated kidney injury via AMPK-dependent metabolic reprogramming, revealing a promising therapeutic strategy for AKI.

PFKFB2-mediated glycolysis promotes lactate-driven continual efferocytosis by macrophages.

Resolving-type macrophages prevent chronic inflammation by clearing apoptotic cells through efferocytosis. These macrophages are thought to rely mainly on oxidative phosphorylation, but emerging evidence suggests a possible link between efferocytosis and glycolysis. To gain further insight into this issue, we investigated molecular-cellular mechanisms involved in efferocytosis-induced macrophage glycolysis and its consequences. We found that efferocytosis promotes a transient increase in macrophage glycolysis that is dependent on rapid activation of the enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 2 (PFKFB2), which distinguishes this process from glycolysis in pro-inflammatory macrophages. Mice transplanted with activation-defective PFKFB2 bone marrow and then subjected to dexamethasone-induced thymocyte apoptosis exhibit impaired thymic efferocytosis, increased thymic necrosis, and lower expression of the efferocytosis receptors MerTK and LRP1 on thymic macrophages compared with wild-type control mice. In vitro mechanistic studies revealed that glycolysis stimulated by the uptake of a first apoptotic cell promotes continual efferocytosis through lactate-mediated upregulation of MerTK and LRP1. Thus, efferocytosis-induced macrophage glycolysis represents a unique metabolic process that sustains continual efferocytosis in a lactate-dependent manner. The differentiation of this process from inflammatory macrophage glycolysis raises the possibility that it could be therapeutically enhanced to promote efferocytosis and resolution in chronic inflammatory diseases.

Mutation of regulatory phosphorylation sites in PFKFB2 does not affect the anti-fibrotic effect of metformin in the kidney.

The anti-fibrotic effect of metformin has been widely demonstrated. Fibrosis in the kidney after injury is associated with reduced expression of genes involved in both fatty acid and glycolytic energy metabolism. We have previously reported that the anti-fibrotic effect of metformin requires phosphoregulation of fatty acid oxidation by AMP-activated protein kinase (AMPK). To determine whether metformin also acts via regulation of glycolysis, we mutated regulatory phosphosites in the PFKFB2 isoform of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB2), a key regulator of glycolysis in the kidney. Mice with inactivating knockin (KI) mutations of the phosphorylation sites in PFKFB2 (PFKFB2 KI mice), which reduces the ability to increase the rate of glycolysis following stimulation, were used. Metformin was administered via drinking water to mice with a unilateral ureteric obstruction (UUO) model of renal fibrosis. In the PFKFB2 KI mice treated with metformin, there was decreased fibrosis and macrophage infiltration following UUO as assessed by Western blot for fibronectin and RT-PCR for α-smooth muscle actin, collagen 3, and F4.80, and confirmed by histology. Expression of the inducible PFKFB3 isoform was increased with metformin in UUO in both WT and PFKFB2 KI mice. There was no significant difference between WT and PFKFB2 KI mice treated with metformin in the degree of fibrosis following UUO in any of the Western blot or RT-PCR parameters that were measured. These data show that inhibition of the regulation of glycolysis by PFKFB2 does not diminish the anti-fibrotic effect of metformin in a model of renal fibrosis.

Understanding Donor-derived Cell-free DNA in Kidney Transplantation: An Overview and Case-based Guide for Clinicians.

Kidney transplant recipients undergo lifelong monitoring of allograft function and evaluation for transplant complications. The current monitoring paradigm utilizes blood, urine, and tissue markers that are insensitive, nonspecific, or invasive to obtain. As a result, problems are detected late, after significant damage has accrued, and often beyond the time at which complete resolution is possible. Indeed, most kidney transplants eventually fail, usually because of chronic rejection and other undetected injury. There is a clear need for a transplant-specific biomarker that enables a proactive approach to monitoring via early detection of reversible pathology. A biomarker that supports timely and personalized treatment would assist in achieving the ultimate goal of improving allograft survival and limiting therapeutic toxicity to the recipient. Donor-derived cell-free DNA (ddcfDNA) has been proposed as one such transplant biomarker. Although the test is presently utilized most in the United States, it is conceivable that its use will become more widespread. This review covers aspects of ddcfDNA that support informed use of the test by general nephrologists, including the basic biology of ddcfDNA, methodological nuances of testing, and general recommendations for use in the kidney transplant population. Clinical contexts are used to illustrate evidence-supported interpretation of ddcfDNA results and subsequent management. Finally, knowledge gaps and areas for further study are discussed.

Elevated serum urea-to-creatinine ratio is associated with adverse inpatient clinical outcomes in non-end stage chronic kidney disease.

To better understand the role of the urea-to-creatinine ratio in chronic kidney disease patients, we assessed the epidemiology of the urea-to-creatinine ratio among hospitalised chronic kidney disease patients, and the association between the urea-to-creatinine ratio and inpatient clinical outcomes. This retrospective cohort study (n = 11,156) included patients with at least two eGFR values < 60 mL/min/1.73m2 measured greater than 90-days apart and admitted to a tertiary hospital between 2014 and 2019. Dialysis and renal transplant patients were excluded. Adjusted odds ratios for factors associated with an elevated urea-to-creatinine ratio were calculated. Multivariate regression was conducted to identify the relationship between elevated UCR and inpatient mortality, intensive care admission, hospital readmission and hospital length-of-stay. Urea-to-creatinine ratio > 100 was present in 27.67% of hospital admissions. Age ≥ 65 years, female gender, gastrointestinal tract bleeding, heart failure, acute kidney injury and lower serum albumin were associated with elevated urea-to-creatinine ratio. Higher urea-to-creatinine ratio level was associated with greater rates of inpatient mortality, hospital readmission within 30-days and longer hospital length-of-stay. Despite this, there was no statistically significant association between higher urea-to-creatinine ratio and intensive care unit admission. Elevated urea-to-creatinine ratio is associated with poor clinical outcomes in chronic kidney disease inpatients. This warrants further investigation to understand the pathophysiological basis for this relationship and to identify effective interventions.

Blocking AMPK signalling to acetyl-CoA carboxylase increases cisplatin-induced acute kidney injury and suppresses the benefit of metformin.

BACKGROUND: Acute kidney injury (AKI) is accompanied by dysregulation of cellular energy metabolism and accumulation of intracellular lipid. Phosphorylation of acetyl-CoA carboxylase (ACC) by AMP-activated protein kinase (AMPK) inhibits fatty acid synthesis and promotes fatty acid oxidation (FAO), vital for kidney tubular epithelial cells (TECs). The diabetes drug metformin is protective in models of AKI; however, it is not known whether ACC phosphorylation plays a role. METHODS: Cisplatin-induced AKI (CI-AKI) was established in ACC1/2 double knock-in (ACC1/2DKI) mice, harbouring mutations that disrupt fatty acid metabolism, and the role of metformin was studied in this model. Outcomes measured included serum biochemistry, expression of kidney injury markers such as neutrophil gelatinase-associated lipocalin (NGAL), and metabolomic analysis. FINDINGS: ACC1/2DKI mice demonstrated more severe CI-AKI than wild type (WT), as assessed by serum urea and creatinine, histological injury, and expression of NGAL and interleukin-6. Metformin protected against AKI in WT mice, shown by reduced NGAL, but this effect was absent in ACC1/2DKI mice. In cultured TECs exposed to cisplatin, metformin reduced expression of cleaved caspase-3, however, this effect was diminished in ACC1/2DKI TECs. Analysis of kidney polar metabolites found numerous differences between metformin-treated CI-AKI in ACC1/2DKI and WT mice, involving multiple pathways of amino acid, nucleoside, and energy metabolism. INTERPRETATION: Severity of CI-AKI is exacerbated by the inability to regulate metabolism via phosphorylation of ACC. ACC phosphorylation contributes to the protective effect of metformin against AKI, influencing multiple mechanisms involved in the pathogenesis of kidney injury.

Cardiovascular Complications of Interatrial Conduction Block: JACC State-of-the-Art Review.

Interatrial block (IAB) is an electrocardiographic pattern describing the conduction delay between the right and left atria. IAB is classified into 3 degrees of block that correspond to decreasing conduction in the region of Bachmann's bundle. Although initially considered benign in nature, specific subsets of IAB have been associated with atrial arrhythmias, elevated thromboembolic stroke risk, cognitive impairment, and mortality. As the pathophysiologic relationships between IAB and stroke are reinforced, investigation has now turned to the potential benefit of early detection, atrial imaging, cardiovascular risk factor modification, antiarrhythmic pharmacotherapy, and stroke prevention with oral anticoagulation. This review provides a contemporary overview of the epidemiology, pathophysiology, diagnosis, and management of IAB, with a focus on future directions.

Independent of Renox, NOX5 Promotes Renal Inflammation and Fibrosis in Diabetes by Activating ROS-Sensitive Pathways.

Excessive production of renal reactive oxygen species (ROS) plays a major role in diabetic kidney disease (DKD). Here, we provide key findings demonstrating the predominant pathological role of the pro-oxidant enzyme NADPH oxidase 5 (NOX5) in DKD, independent of the previously characterized NOX4 pathway. In patients with diabetes, we found increased expression of renal NOX5 in association with enhanced ROS formation and upregulation of ROS-sensitive factors early growth response 1 (EGR-1), protein kinase C-α (PKC-α), and a key metabolic gene involved in redox balance, thioredoxin-interacting protein (TXNIP). In preclinical models of DKD, overexpression of NOX5 in Nox4-deficient mice enhances kidney damage by increasing albuminuria and augmenting renal fibrosis and inflammation via enhanced ROS formation and the modulation of EGR1, TXNIP, ERK1/2, PKC-α, and PKC-ε. In addition, the only first-in-class NOX inhibitor, GKT137831, appears to be ineffective in the presence of NOX5 expression in diabetes. In vitro, silencing of NOX5 in human mesangial cells attenuated upregulation of EGR1, PKC-α, and TXNIP induced by high glucose levels, as well as markers of inflammation (TLR4 and MCP-1) and fibrosis (CTGF and collagens I and III) via reduction in ROS formation. Collectively, these findings identify NOX5 as a superior target in human DKD compared with other NOX isoforms such as NOX4, which may have been overinterpreted in previous rodent studies.

Effect of Elevated C-Reactive Protein on Outcomes After Complex Percutaneous Coronary Intervention for Angina Pectoris.

Inflammation and procedural complexity are individually associated with adverse outcomes after percutaneous coronary intervention (PCI). We aimed to evaluate the association of high sensitivity C-reactive protein (hsCRP) with adverse events according to PCI complexity. We included patients with available hsCRP levels who underwent PCI at our center from 2012 to 2017. We compared patients with hsCRP ≥3 versus <3 mg/L. Complex PCI was defined as having ≥1 of the following: ≥3 different target vessels, ≥3 lesions treated, ≥3 stents implanted, bifurcation lesion treated with 2 stents, chronic total occlusion as target lesion, or total stent length >60 mm. The primary end point was major adverse cardiac events (MACEs) (composite of all-cause death, myocardial infarction, or target vessel revascularization) at 1 year. A total of 11,979 patients were included, of which 2,840 (24%) underwent complex PCI. In those, 767 (27%) had hsCRP ≥3 mg/L. The 1-year incidence of MACE was 6% (noncomplex PCI, low hsCRP), 10% (noncomplex PCI, high hsCRP), 10% (complex PCI, low hsCRP), and 15% (complex PCI, high hsCRP). Overall, hsCRP ≥3 mg/L was associated with an increased risk of MACE compared with hsCRP <3 mg/L; this was independent of the number of complex PCI features: 0 (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI] 1.27 to 1.86), 1 (adjusted HR 1.77; 95% CI 1.21 to 2.60), or ≥2 (adjusted HR 1.21; 95% CI 0.80 to 1.83) (pinteraction = 0.42). In conclusion, in patients who underwent PCI, elevated hsCRP is associated with an increased risk of ischemic events. The effect of elevated hsCRP on cardiovascular risk is consistent regardless of PCI complexity.

Myocardial Bridging: Diagnosis, Functional Assessment, and Management: JACC State-of-the-Art Review.

Myocardial bridging (MB) is a congenital coronary anomaly in which a segment of the epicardial coronary artery traverses through the myocardium for a portion of its length. The muscle overlying the artery is termed a myocardial bridge, and the intramyocardial segment is referred to as a tunneled artery. MB can occur in any coronary artery, although is most commonly seen in the left anterior descending artery. Although traditionally considered benign in nature, increasing attention is being given to specific subsets of MB associated with ischemic symptomatology. The advent of contemporary functional and anatomic imaging modalities, both invasive and noninvasive, have dramatically improved our understanding of dynamic pathophysiology associated with MBs. This review provides a contemporary overview of epidemiology, pathobiology, diagnosis, functional assessment, and management of MBs.

Dialysis and driving: an anonymous survey of patients receiving dialysis for end-stage kidney disease.

BACKGROUND: Driving is a complex task requiring multiple cognitive domains and the musculoskeletal system. Cognitive dysfunction is associated with driving impairment. Dialysis patients are known to have a high prevalence of cognitive impairment and other comorbidities, and may be at risk of driving impairment. No Australian guidelines address driving safety in dialysis patients. AIMS: To estimate the proportion of dialysis patients who were driving and those at risk of driving impairment, and to investigate the agreement between objective and subjective markers of risk. METHODS: This single-centre study involved dialysis patients voluntarily completing two questionnaires relating to risk of driving impairment; the first questionnaire focussed on objective markers, and the second questionnaire focussed on subjective markers. Risk of driving impairment was established using pre-determined criteria, and the agreement between objective and subjective markers was estimated using Cohen kappa. RESULTS: A total of 44.8% (99/221) of patients participated; 76.8% (76/99) of participants were driving, and 76.3% (58/76) of drivers were at risk of driving impairment. Factors associated with at-risk driving included post dialysis dizziness, leg weakness or numbness, falling asleep while driving and hypoglycaemia. Sixteen patients reported collisions since commencing dialysis. The questionnaires displayed slight agreement (Cohen kappa = 0.20) between objective and subjective markers. CONCLUSIONS: Dialysis patients are at risk of driving impairment based on self-reported questionnaire responses. Discrepancies between patients' perceptions and objective markers were apparent. Further research into appropriate risk assessments, as well as development of guidelines to aid in determining driving safety in dialysis patients, is needed.

Serum potassium abnormalities in chronic kidney disease: prevalence, patient characteristics and clinical outcomes.

BACKGROUND: Abnormalities in serum potassium are a well known complication of chronic kidney disease (CKD), but little is known about their impact on inpatient outcomes. AIMS: To better understand the role of dyskalaemia in hospital in-patients, we assessed the epidemiology of potassium disorders among CKD patients, and the association between admission potassium and inpatient mortality or intensive care unit (ICU) requirement. METHODS: This retrospective hospital-based cohort study (n = 11 156) included patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 admitted to Austin Health between 2014 and 2018 and who had an admission potassium value. Dialysis patients or those with a renal transplant were excluded. Multivariate logistic analysis was conducted to identify factors associated with hyperkalaemia (≥5.5 mmol/L) and hypokalaemia (<3.5 mmol/L). Odds ratios for inpatient mortality and ICU admission between potassium categories were obtained by multivariate regression with adjustments for demographics, renal function and comorbidities. RESULTS: Hyperkalaemia and hypokalaemia were present in 6.86% and 2.94% of hospital admissions respectively. In multivariate regression male sex, lower eGFR, diabetes and cardiac failure were associated with higher odds of hyperkalaemia. Thiazide diuretics, loop diuretics, infectious disease and endocrine pathology were associated with higher odds of hypokalaemia. A U-shaped association was noted between potassium and inpatient mortality. Potassium <4.0 mmol/L and ≥5.0 mmol/L was associated with increased mortality. Only patients with potassium ≥5.5 mmol/L had increased ICU admission risk. CONCLUSION: Derangements in potassium frequently occur in CKD inpatients and are independently associated with higher mortality and ICU requirement. Further studies are required to determine whether interventions to maintain normokalaemia improve outcomes in this population.

Mutation of regulatory phosphorylation sites in PFKFB2 worsens renal fibrosis.

Fatty acid oxidation is the major energy pathway used by the kidney, although glycolysis becomes more important in the low oxygen environment of the medulla. Fatty acid oxidation appears to be reduced in renal fibrosis, and drugs that reverse this improve fibrosis. Expression of glycolytic genes is more variable, but some studies have shown that inhibiting glycolysis reduces renal fibrosis. To address the role of glycolysis in renal fibrosis, we have used a genetic approach. The crucial control point in the rate of glycolysis is 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase. Phosphorylation of the kidney isoform, PFKFB2, on residues Ser468 and Ser485 stimulates glycolysis and is the most important mechanism regulating glycolysis. We generated transgenic mice with inactivating mutations of Ser468 and Ser485 in PFKFB2 (PFKFB2 KI mice). These mutations were associated with a reduced ability to increase glycolysis in primary cultures of renal tubular cells from PFKFB2 KI mice compared to WT cells. This was associated in PFKFB2 KI mice with increased renal fibrosis, which was more severe in the unilaternal ureteric obstruction (UUO) model compared with the folic acid nephropathy (FAN) model. These studies show that phosphorylation of PFKFB2 is important in limiting renal fibrosis after injury, indicating that the ability to regulate and maintain adequate glycolysis in the kidney is crucial for renal homeostasis. The changes were most marked in the UUO model, probably reflecting a greater effect on distal renal tubules and the greater importance of glycolysis in the distal nephron.

Complement C5a Induces Renal Injury in Diabetic Kidney Disease by Disrupting Mitochondrial Metabolic Agility.

The sequelae of diabetes include microvascular complications such as diabetic kidney disease (DKD), which involves glucose-mediated renal injury associated with a disruption in mitochondrial metabolic agility, inflammation, and fibrosis. We explored the role of the innate immune complement component C5a, a potent mediator of inflammation, in the pathogenesis of DKD in clinical and experimental diabetes. Marked systemic elevation in C5a activity was demonstrated in patients with diabetes; conventional renoprotective agents did not therapeutically target this elevation. C5a and its receptor (C5aR1) were upregulated early in the disease process and prior to manifest kidney injury in several diverse rodent models of diabetes. Genetic deletion of C5aR1 in mice conferred protection against diabetes-induced renal injury. Transcriptomic profiling of kidney revealed diabetes-induced downregulation of pathways involved in mitochondrial fatty acid metabolism. Interrogation of the lipidomics signature revealed abnormal cardiolipin remodeling in diabetic kidneys, a cardinal sign of disrupted mitochondrial architecture and bioenergetics. In vivo delivery of an orally active inhibitor of C5aR1 (PMX53) reversed the phenotypic changes and normalized the renal mitochondrial fatty acid profile, cardiolipin remodeling, and citric acid cycle intermediates. In vitro exposure of human renal proximal tubular epithelial cells to C5a led to altered mitochondrial respiratory function and reactive oxygen species generation. These experiments provide evidence for a pivotal role of the C5a/C5aR1 axis in propagating renal injury in the development of DKD by disrupting mitochondrial agility, thereby establishing a new immunometabolic signaling pathway in DKD.

Adjunct Pharmacotherapy After Transcatheter Aortic Valve Replacement: Current Status and Future Directions.

Transcatheter aortic valve replacement (TAVR) is a validated treatment option for severe aortic stenosis. Ischemic and thrombotic complications remain important and strongly correlate with mortality. The optimal postprocedural antithrombotic strategy for prevention of thrombotic events remains unclear. The international guidelines for medical management following TAVR are discordant, allowing for significant variance in prescribing habits. The optimal treatment strategy has yet to be delineated. Clinical trials are ongoing to assess the risks and benefits of various strategies. We discuss the pathobiology and rationale for antithrombotic therapy after TAVR, review current evidence and guidelines, and offer a concise evidence-based approach to this subject.

Absence of the ß1 subunit of AMP-activated protein kinase reduces myofibroblast infiltration of the kidneys in early diabetes.

Activation of the heterotrimeric energy-sensing kinase AMP-activated protein kinase (AMPK) has been reported to improve experimental diabetic kidney disease. We examined the effect of type 1 diabetes in wild-type (WT) mice and mice lacking the ß1 subunit of AMPK (AMPK ß1-/- mice), which have reduced AMPK activity in kidneys and other organs. Diabetes was induced using streptozotocin (STZ) and the animals followed up for 4 weeks. Hyperglycaemia was more severe in diabetic AMPK ß1-/- mice, despite the absence of any difference in serum levels of insulin, adiponectin and leptin. There was no change in AMPK activity in the kidneys of diabetic WT mice by AMPK activity assay, or phosphorylation of either the αT172 activation site on the α catalytic subunit of AMPK or the AMPK-specific phosphosite S79 on acetyl CoA carboxylase 1 (ACC1). Phosphorylation of the inhibitory αS485 site on the α subunit of AMPK was significantly increased in the WT diabetic mice compared to non-diabetic controls. Despite increased plasma glucose levels in the diabetic AMPK ß1-/- mice, there were fewer myofibroblasts in the kidneys compared to diabetic WT mice, as evidenced by reduced α-smooth muscle actin (α-SMA) protein by Western blot, mRNA by qRT-PCR and fewer α-SMA-positive cells by immunohistochemical staining. Albuminuria was also reduced in the AMPK ß1-/- mice. In contrast to previous studies, therefore, myofibroblasts were reduced in the kidneys of AMPK ß1-/- diabetic mice compared to diabetic WT mice, despite increased circulating glucose, suggesting that AMPK can worsen renal fibrosis in type 1 diabetes.

Effect of stent diameter in women undergoing percutaneous coronary intervention with early- and new-generation drug-eluting stents: From the WIN-DES collaboration.

BACKGROUND: The risk of stent thrombosis (ST) or target lesion revascularization (TLR) is increased with smaller stent diameters (SD). Whether SD has a deleterious effect in women treated with early- vs. new-generation drug-eluting stents (DES) is unknown. METHODS: We pooled patient-level data from 26 randomized control trials of DES. Only women treated with DES were included. Subjects were stratified according to SD: small, SD ≤ 2.75 mm; intermediate, 2.75 mm < SD ≤ 3.25 mm; and large, SD ≥ 3.25 mm. Endpoints of interest were 3-year definite ST, TLR, major adverse cardiac events (MACE: the composite of death, myocardial infarction or TLR) and death. RESULTS: Of 6413 women, 2274 (35.0%) had a small SD, 2448 (38.0%) had an intermediate SD, and 1691 (26.0%) had a large SD. By multivariable analysis, stent diameter (per 0.25 mm decrease) was associated with an increased risk of TLR and ST, which was uniform in terms of magnitude and direction between early- and new-generation DES. There were no differences in MACE or death across groups. CONCLUSION: Small SD in women undergoing PCI is associated with an increased risk of definite ST and TLR, consistently with both early- and new-generation DES.

Three Dimensional Glomerular Reconstruction: A Novel Approach to Evaluate Renal Microanatomy in Diabetic Kidney Disease.

Mesangial metrics reflect glomerular filtration surface area in diabetes. The point-sampled intercept (PSI) method is the conventional method to calculate these parameters. However, this is time consuming and subject to underestimation. We introduce a novel three-dimensional (3D) reconstruction method applicable to light microscopy to measure mesangial metrics. Transmission electron microscopy (TEM), PSI and our new 3D imaging methods were used to quantify mesangial metrics from 22 patients with type 2 diabetes, normo-, micro- and macroalbuminuria and an estimated glomerular filtration rate of <60 mL/min/1.73 m2. Repeated-measures ANOVA test was used to test the equality of the measurement means from the three methods and the degree of inter method variability. Repeated-measures and post-estimation ANOVA tests together with correlation coefficient measurements were used to compare the methods with TEM as reference. There was a statistically significant difference in mesangial volume measurements (F(2, 16) = 15.53, p = 0.0002). The PSI method underestimated measurements compared to TEM and 3D methods by 30% (p = 0.001) and 15%, respectively (p < 0.001). 3D and TEM measurements did not differ significantly. 3D reconstruction is a reliable and time efficient method for calculating mesangial metrics. It may prove to be a useful tool in clinical and experimental diabetic kidney disease.

Diagnostic application of kidney allograft-derived absolute cell-free DNA levels during transplant dysfunction.

Graft-derived cell-free DNA (donor-derived cell-free DNA) is an emerging marker of kidney allograft injury. Studies examining the clinical validity of this biomarker have previously used the graft fraction, or proportion of total cell-free DNA that is graft-derived. The present study evaluated the diagnostic validity of absolute measurements of graft-derived cell-free DNA, as well as calculated graft fraction, for the diagnosis of graft dysfunction. Plasma graft-derived cell-free DNA, total cell-free DNA, and graft fraction were correlated with biopsy diagnosis as well as individual Banff scores. Sixty-one samples were included in the analysis. For the diagnosis of antibody mediated rejection, the receiver-operator characteristic area under the curves of graft-derived cell-free DNA and graft fraction were 0.91 (95% CI 0.82-0.98) and 0.89 (95% CI 0.79-0.98), respectively. Both measures did not diagnose borderline or type 1A cellular mediated rejection. Graft fraction was associated with a broader range of Banff lesions, including lesions associated with cellular mediated rejection, while graft-derived cell-free DNA appeared more specific for antibody mediated rejection. Limitations of this study include a small sample size and lack of a validation cohort. The capacity for absolute quantification, and lower barriers to implementation of this methodology recommend it for further study.