Healthy Kidney Research Articles

Phosphodiesterase inhibitor ameliorates senescent changes of renal interstitial pericytes in aging kidney.

Pericytes are mesenchymal cells that surround endothelial cells, playing a crucial role in angiogenesis and vessel maturation. Additionally, they are associated with interstitial fibrosis as a major contributor to renal myofibroblasts. In this study, we aim to investigate whether the phosphodiesterase inhibitor, pentoxifylline (PTX), can ameliorate aging-related functional and histological deterioration in the kidney. We subjected aging C57BL/6 mice, dividing into young, aging, and PTX-treated aging groups. Renal function, albuminuria, and histological changes were assessed. Interstitial pericytes were assessed by immunohistochemistry analysis. We examined changes in pericytes in elderly patients using human kidney tissue obtained from healthy kidney donors for kidney transplantation. Invitro experiments with human pericytes and endothelial cells were performed. Aging mice exhibited declined renal function, increased albuminuria, and aging-related histological changes including mesangial expansion and tubulointerstitial fibrosis. Notably, number of pericytes declined in aging kidneys, and myofibroblasts increased. PTX treatment ameliorated albuminuria, histological alterations, and microvascular rarefaction, as well as modulated angiopoietin expression. Invitro experiments showed PTX reduced cellular senescence and inflammation. Human kidney analysis confirmed similar pericyte changes in aging kidneys. The phosphodiesterase inhibitor, PTX preserved microvascular density and improved renal interstitial fibrosis and inflammation in aging mice kidneys. These protective effects were suggested to be associated with the amelioration of pericytes reduction and the transition to myofibroblasts. Additionally, the upregulation of angiopoietin-1 expression may exert potential impacts. To the best of our knowledge, this is the first report on the changes in renal interstitial pericytes in aging human kidneys.

In Silico and In Vivo Pharmacokinetic Evaluation of 84-B10, a Novel Drug Candidate against Acute Kidney Injury and Chronic Kidney Disease.

Acute kidney injury (AKI) and chronic kidney disease (CKD) have become public health problems due to high morbidity and mortality. Currently, drugs recommended for patients with AKI or CKD are extremely limited, and candidates based on a new mechanism need to be explored. 84-B10 is a novel 3-phenylglutaric acid derivative that can activate the mitochondrial protease, Lon protease 1 (LONP1), and may protect against cisplatin-induced AKI and unilateral ureteral obstruction- or 5/6 nephrectomy [5/6Nx]-induced CKD model. Preclinical studies have shown that 84-B10 has a good therapeutic effect, low toxicity, and is a good prospect for further development. In the present study, the UHPLC-MS/MS method was first validated then applied to the pharmacokinetic study and tissue distribution of 84-B10 in rats. Physicochemical properties of 84-B10 were then acquired in silico. Based on these physicochemical and integral physiological parameters, a physiological based pharmacokinetic (PBPK) model was developed using the PK-Sim platform. The fitting accuracy was estimated with the obtained experimental data. Subsequently, the validated model was employed to predict the pharmacokinetic profiles in healthy and chronic kidney injury patients to evaluate potential clinical outcomes. Cmax in CKD patients was about 3250 ng/mL after a single dose of 84-B10 (0.41 mg/kg), and Cmax,ss was 1360 ng/mL after multiple doses. This study may serve in clinical dosage setting in the future.

Estimation of Glomerular Filtration Rate Using the New Ekfc Equation in Healthy and Chronic Kidney Disease Adult Subjects from Sub-Saharan Africa

Introduction: Since the publication of the first equation for estimate creatinine clearance in 1957, several other equations estimating glomerular filtration rate have followed in succession. To date, a new equation has been published by the European Kidney Function Consortium (EKFC) in 2021, which would have the advantage of being adaptable to any type of population. In this study, we aimed to evaluate the performance of this new equation in our black African population of healthy subjects and subjects with chronic kidney disease.
 Material and Methods: This was a cross-sectional study involving 192 healthy subjects and 183 subjects with chronic kidney disease. Plasma iohexol clearance (mGFR) constituted́ the reference method used to measure glomerular filtration rate and allowed evaluation of all equation variants (EKFC crea, EKFC cys, EKFC crea-cys). Equation performance was studied by calculating the 95% CI bias, the interquartile range (25% percentile, 75% percentile) and the 30% accuracy (P30) compared with the reference method.
 Results: All EKFC variants in both populations (healthy subjects and chronic kidney disease subjects) had biases below 5 ml/min/1.73 m2. Biases were therefore acceptable. On the other hand, P30s were less good in subjects with chronic kidney disease.
 Conclusion: Thus, the EKFC equation performs well in the healthy population, but its evaluation in the chronic kidney disease population needs to be strengthened on the basis of larger cohorts.

Convolutional Neural Network Model for Segmentation and Classification of Clear Cell Renal Cell Carcinoma Based on Multiphase CT Images.

(1) Background: Computed tomography (CT) imaging challenges in diagnosing renal cell carcinoma (RCC) include distinguishing malignant from benign tissues and determining the likely subtype. The goal is to show the algorithm's ability to improve renal cell carcinoma identification and treatment, improving patient outcomes. (2) Methods: This study uses the European Deep-Health toolkit's Convolutional Neural Network with ECVL, (European Computer Vision Library), and EDDL, (European Distributed Deep Learning Library). Image segmentation utilized U-net architecture and classification with resnet101. The model's clinical efficiency was assessed utilizing kidney, tumor, Dice score, and renal cell carcinoma categorization quality. (3) Results: The raw dataset contains 457 healthy right kidneys, 456 healthy left kidneys, 76 pathological right kidneys, and 84 pathological left kidneys. Preparing raw data for analysis was crucial to algorithm implementation. Kidney segmentation performance was 0.84, and tumor segmentation mean Dice score was 0.675 for the suggested model. Renal cell carcinoma classification was 0.885 accurate. (4) Conclusion and key findings: The present study focused on analyzing data from both healthy patients and diseased renal patients, with a particular emphasis on data processing. The method achieved a kidney segmentation accuracy of 0.84 and mean Dice scores of 0.675 for tumor segmentation. The system performed well in classifying renal cell carcinoma, achieving an accuracy of 0.885, results which indicates that the technique has the potential to improve the diagnosis of kidney pathology.

Selective Cytotoxicity of Ficus Benjamina Leaf Extract Against Lung Cancer Cells

This study examines the inhibitory effects of chloroform extract (samples A, B, C, D and E) from Ficus benjamina leaves as a cancer treatment by comparing them to the anticancer medicine, Bortezomib (BTZ), and evaluating their effects on lung cancer cell lines. Sample A is the crude chloroform extract from Ficus benjamina leaf; samples B to E are different fractions derived through flash chromatography of the crude chloroform extract. Positive control was Bortezomib and negative control was Dimethyl sulfoxide (DMSO). The test samples were used at two concentrations of 10 µg/ML and 50 µg/ML. BTZ was tested at 1 µM and DMSO at 1 %. According to the findings, sample C showed significant (p<0.05) inhibition of cancer cell lines at 50 µg/ML. The extract's inhibitory activity, however, was shown to be less than that of BTZ. Increased concentrations of the extract showed increased inhibitory activity, supporting the finding that the inhibitory effect of the extract is concentration dependent. At a concentration of 10 µg/ML, extracts A, C, D, and E significantly inhibited lung cancer cell lines as compared to extract B that did not. At both concentrations of 10 µg/ML and µ50 g/ML, the inhibition displayed by bortezomib was noticeably higher than that of all the samples of the chloroform extract of Ficus benjamina leaves. At a concentration of 50 µg/ML, extract C showed a much greater percentage of inhibition against the lung cancer cell lines. Overall, the study shows that Ficus benjamina leaves may be used as an anticancer drug. Sample C showed selective cytotoxicity against the cancer cells while sparing healthy human embryonic kidney (HEK) cells. The extract also exhibits a better therapeutic index than Bortezomib, indicating the possibility of a targeted cancer medication with fewer side effects. To clarify the underlying mechanisms and determine clinical feasibility, more study is required. These results highlight the promise of Ficus benjamina leaf extract in the treatment of cancer, but they also highlight the need for further research to fully comprehend its potential.

Protective effect of pomegranate seed oil against salt toxicity in rat kidneys

Consuming too much salt can have a negative impact on your kidneys. The kidneys play an important role in regulating sodium levels in the body, and excess salt can lead to water retention and increased blood pressure, which in turn can have a negative impact on the kidneys. Excess salt in the diet can contribute to the formation of kidney stones. This is because excess sodium can lead to increased calcium excretion in the urine, which in turn increases the risk of stone formation. An experiment was conducted on rats to study the effect of salt on kidney function. During the experiment, a group of rats received a high dose of salt for a certain period of time, while another group received a regular amount of salt. The results showed that rats that consumed more salt had increased blood pressure and negative changes in kidney function. They also faced problems with fluid retention and the formation of kidney stones. This experiment confirmed that excess salt consumption can negatively affect kidney function and lead to the development of various diseases. Therefore, controlling your salt intake is an important aspect of maintaining a healthy kidney system. Kidney contamination from salt can lead to various diseases such as kidney stones, kidney failure and other genitourinary problems. One way to correct this problem may be to use pomegranate oil. Pomegranate oil contains antioxidants that help reduce inflammation and protect kidney cells from damage. It also improves blood circulation and helps cleanse the kidneys of toxins and waste. Research has shown that consuming pomegranate oil may help improve kidney function, reduce inflammation, and prevent the formation of kidney stones. It can also help lower blood pressure and improve the overall health of the kidney system.

Matrix Metalloproteinase-7 in Urinary Extracellular Vesicles Identifies Rapid Disease Progression in Autosomal Dominant Polycystic Kidney Disease.

There is an unmet need for biomarkers of disease progression in autosomal dominant polycystic kidney disease (ADPKD). This study investigated urinary extracellular vesicles (uEVs) as a source of such biomarkers. Proteomic analysis of uEVs identified matrix metalloproteinase 7 (MMP-7) as a biomarker predictive of rapid disease progression. In validation studies, MMP-7 was predictive in uEVs but not in whole urine, possibly because uEVs are primarily secreted by tubular epithelial cells. Indeed, single-nucleus RNA sequencing showed that MMP-7 was especially increased in proximal tubule and thick ascending limb cells, which were further characterized by a profibrotic phenotype. Together, these data suggest that MMP-7 is a biologically plausible and promising uEV biomarker for rapid disease progression in ADPKD. In ADPKD, there is an unmet need for early markers of rapid disease progression to facilitate counseling and selection for kidney-protective therapy. Our aim was to identify markers for rapid disease progression in uEVs. Six paired case-control groups ( n =10-59/group) of cases with rapid disease progression and controls with stable disease were formed from two independent ADPKD cohorts, with matching by age, sex, total kidney volume, and genetic variant. Candidate uEV biomarkers were identified by mass spectrometry and further analyzed using immunoblotting and an ELISA. Single-nucleus RNA sequencing of healthy and ADPKD tissue was used to identify the cellular origin of the uEV biomarker. In the discovery proteomics experiments, the protein abundance of MMP-7 was significantly higher in uEVs of patients with rapid disease progression compared with stable disease. In the validation groups, a significant >2-fold increase in uEV-MMP-7 in patients with rapid disease progression was confirmed using immunoblotting. By contrast, no significant difference in MMP-7 was found in whole urine using ELISA. Compared with healthy kidney tissue, ADPKD tissue had significantly higher MMP-7 expression in proximal tubule and thick ascending limb cells with a profibrotic phenotype. Among patients with ADPKD, rapid disease progressors have higher uEV-associated MMP-7. Our findings also suggest that MMP-7 is a biologically plausible biomarker for more rapid disease progression.

High-Frame-Rate Volumetric Porcine Renal Vasculature Imaging.

The aim of this study was to assess the feasibility and imaging options of contrast-enhanced volumetric ultrasound kidney vasculature imaging in a porcine model using a prototype sparse spiral array. Transcutaneous freehand in vivo imaging of two healthy porcine kidneys was performed according to three protocols with different microbubble concentrations and transmission sequences. Combining high-frame-rate transmission sequences with our previously described spatial coherence beamformer, we determined the ability to produce detailed volumetric images of the vasculature. We also determined power, color and spectral Doppler, as well as super-resolved microvasculature in a volume. The results were compared against a clinical 2-D ultrasound machine. Three-dimensional visualization of the kidney vasculature structure and blood flow was possible with our method. Good structural agreement was found between the visualized vasculature structure and the 2-D reference. Microvasculature patterns in the kidney cortex were visible with super-resolution processing. Blood flow velocity estimations were within a physiological range and pattern, also in agreement with the 2-D reference results. Volumetric imaging of the kidney vasculature was possible using a prototype sparse spiral array. Reliable structural and temporal information could be extracted from these imaging results.

Altered immune cell phenotypes within chronically ischemic human kidneys distal to occlusive renal artery disease.

Renal artery stenosis (RAS) is a major cause of ischemic kidney disease, which is largely mediated by inflammation. Mapping the immune cell composition in ischemic kidneys might provide useful insight into the disease pathogenesis and uncover therapeutic targets. We used mass cytometry (CyTOF) to explore the single-cell composition in a unique data set of human kidneys nephrectomized due to chronic occlusive vascular disease (RAS, n = 3), relatively healthy donor kidneys (n = 6), and unaffected sections of kidneys with renal cell carcinoma (RCC, n = 3). Renal fibrosis and certain macrophage populations were also evaluated in renal sections. Cytobank analysis showed in RAS kidneys decreased cell populations expressing epithelial markers (CD45-/CD13+) and increased CD45+ inflammatory cells, whereas scattered tubular-progenitor-like cells (CD45-/CD133+/CD24+) increased compared with kidney donors. Macrophages switched to proinflammatory phenotypes in RAS, and the numbers of IL-10-producing dendritic cells (DC) were also lower. Compared with kidney donors, RAS kidneys had decreased overall DC populations but increased plasmacytoid DC. Furthermore, senescent active T cells (CD45+/CD28+/CD57+), aged neutrophils (CD45+/CD15+/CD24+/CD11c+), and regulatory B cells (CD45+/CD14-/CD24+/CD44+) were increased in RAS. RCC kidneys showed a distribution of cell phenotypes comparable with RAS but less pronounced, accompanied by an increase in CD34+, CD370+, CD103+, and CD11c+/CD103+ cells. Histologically, RAS kidneys showed significantly increased fibrosis and decreased CD163+/CD141+ cells. The single-cell platform CyTOF enables the detection of significant changes in renal cells, especially in subsets of immune cells in ischemic human kidneys. Endogenous pro-repair cell types in RAS warrant future study for potential immune therapy.NEW & NOTEWORTHY The single-cell platform mass cytometry (CyTOF) enables detection of significant changes in one million of renal cells, especially in subsets of immune cells in ischemic human kidneys distal to renal artery stenosis (RAS). We found that pro-repair cell types such as scattered tubular-progenitor-like cells, aged neutrophils, and regulatory B cells show a compensatory increase in RAS. Immune cell phenotype changes may reflect ongoing inflammation and impaired immune defense capability in the kidneys.

Interpreting pathology test result values with comparators (< , >) in Electronic Health Records research: an OpenSAFELY short data report.

Numeric results of pathology tests are sometimes returned as a range rather than a precise value, e.g. "<10". In health data research, test result values above or below clinical threshold values are often used to categorise patients into groups; however comparators (<, > etc) are typically stored separately to the numeric values and often ignored, but may influence interpretation. With the approval of NHS England we used routine clinical data from 24 million patients in OpenSAFELY to identify pathology tests with comparators commonly attached to result values. For each test we report: the proportion returned with comparators present, split by comparator type and geographic region; the specific numeric result values returned with comparators, and the associated reference limits. We identified 11 common test codes where at least one in four results had comparators. Three codes related to glomerular filtration rate (GFR) tests/calculations, with 31-45% of results returned with "≥" comparators. At least 90% of tests with numeric values 60 and 90 represented ranges (≥60 and ≥90 respectively) rather than exact values. The other tests - four blood tests (Nucleated red blood cell count, Plasma C reactive protein, Tissue transglutaminase immunoglobulin A, and Rheumatoid factor), two urine tests (albumin/microalbumin) and two faecal tests (calprotectin and quantitative faecal immunochemical test) - were returned with "≤" comparators (29-86%). Comparators appear commonly in certain pathology tests in electronic health records. For most common affected tests, we expect there to be minimal implications for researchers for most use-cases. However, care should be taken around whether results falling exactly on clinical threshold values should be considered "normal" or "abnormal". Results from GFR tests/calculations cannot reliably distinguish between mild kidney disease (stage G2, 60-<90) versus healthy kidney function (90+). More broadly, health data researchers using numeric test result values should consider the impact of comparators.

Higher Content but No Specific Activity in Gelatinase B (MMP-9) Compared with Gelatinase A (MMP-2) in Human Renal Carcinoma.

Gelatinases belong to a group of enzymes known as matrix metalloproteinases (MMPs). Gelatinases A and B (MMP-2 and MMP-9, respectively) are the enzymes with the highest ability to destroy collagen, primarily type IV collagen, which is an essential component of the base membrane. Hence, it can be assumed that they are involved, among other things, with the metastasis process of cancer. As a result, the objective of this study was to assess the presence, activity, and expression of selected gelatinases in human renal cancer. Healthy (n = 20) and clear-cell kidney cancer tissue samples (G2 n = 10, G3 n = 10) were analyzed. The presence and content of MMPs were measured using the Western blot and ELISA methods, respectively. The activity (actual and specific) was analyzed with a fluorimetric method. The presence of both investigated enzymes was demonstrated in the representative zymogram. MMP-9 showed the most intensive saturation. It has been observed that both gelatinases occur primarily in high molecular complexes in the human kidney, regardless of whether it is a control or tumor tissue. Both gelatinases were present in comparable amounts in healthy tissues of the kidney. MMP-9 showed a higher content than MMP-2 in both renal cancer grades, but we observed the enhanced activity of both gelatinases with an increase in the grade of renal cancer. A higher MMP-9 content and, on the other hand, lower specific activity in the cancer tissue suggest that MMP-9 is predominantly present in an inactive form in renal cancer. The higher activity of MMP-9 demonstrated using the zymography method may be a cause of different values of activity that depend on the phase of the carcinogenic process. The present study revealed changes in the tested gelatinases in healthy and cancerous tissues of renal cell carcinoma. Therefore, it can be concluded that matrix metalloproteinases 2 and 9 are enzymes directly involved in carcinogenesis, and hence, it seems that MMPs may have potential in the diagnosis and treatment of renal carcinoma.

Differential expression of HIF1A and its downstream target VEGFA in the main subtypes of renal cell carcinoma and their impact on patient survival.

Renal cell carcinoma (RCC) represents around 3% of all cancers, with the most frequent histological types being clear-cell RCC (ccRCC), followed by papillary (pRCC) and chromophobe (chRCC). Hypoxia-inducible factors (HIFs), which promote the expression of various target genes, including vascular endothelial growth factor (VEGF) and the high- affinity glucose transporter 1, have an important role in the pathogenesis of RCC. This study investigated the immunohistochemical expression of HIF-1α and VEGF-A, showing significantly higher HIF-1α nuclear expression in pRCC compared to ccRCC, while there was no significant difference in VEGF-A protein expression between the analyzed histological RCC subtypes. The quantitative reverse transcription polymerase chain reaction for HIF1A showed no statistical difference between histological types. Data from publicly available RNA sequencing databases were analyzed and showed that, compared to healthy kidney tissue, VEGFA was significantly up-regulated in ccRCC and significantly down-regulated in pRCC. The comparison between histological subtypes of RCC revealed that VEGFA was significantly up-regulated in ccRCC compared to both pRCC and chRCC. There was no statistically significant difference in survival time between HIF1A high- and low-expression groups of patients. As for VEGFA expression, pRCC patients with low expression had a significantly higher survival rate compared to patients with high VEGFA expression.

Correlating Deep Learning-Based Automated Reference Kidney Histomorphometry with Patient Demographics and Creatinine.

Reference histomorphometric data of healthy human kidneys are largely lacking due to laborious quantitation requirements. Correlating histomorphometric features with clinical parameters through machine learning approaches can provide valuable information about natural population variance. To this end, we leveraged deep learning, computational image analysis, and feature analysis to associate the relationship of histomorphometry with patient age, sex, serum creatinine (SCr), and estimated glomerular filtration rate (eGFR) in a multinational set of reference kidney tissue sections. A panoptic segmentation neural network was developed and used to segment viable and sclerotic glomeruli, cortical and medullary interstitia, tubules, and arteries/arterioles in the digitized images of 79 periodic acid-Schiff-stained human nephrectomy sections showing minimal pathologic changes. Simple morphometrics (e.g., area, radius, density) were quantified from the segmented classes. Regression analysis aided in determining the association of histomorphometric parameters with age, sex, SCr, and eGFR. Our deep-learning model achieved high segmentation performance for all test compartments. The size and density of glomeruli, tubules, and arteries/arterioles varied significantly among healthy humans, with potentially large differences between geographically diverse patients. Glomerular size was significantly correlated with SCr and eGFR. Slight, albeit significant, differences in renal vasculature were observed between sexes. Glomerulosclerosis percentage increased and cortical density of arteries/arterioles decreased, as a function of increasing age. Using deep learning, we automated precise measurements of kidney histomorphometric features. In the reference kidney tissue, several histomorphometric features demonstrated significant correlation to patient demographics, SCr, and eGFR. Deep learning tools can increase the efficiency and rigor of histomorphometric analysis.

The correlation between GFR and unit renal volume in infants with hydronephrosis measured by two imaging methods

The purpose of this study was to investigate the correlation between GFR and unit renal volume in infants with congenital hydronephrosis measured by 99mTc-DMSA static renal imaging and ultrasonography. According to the classification of hydronephrosis, 38 infants aged 0–12 months with congenital hydronephrosis were divided into six groups: healthy kidney groups, mild hydronephrosis groups, and severe hydronephrosis groups. Within one week, all patients underwent ultrasound, diuretic dynamic renal imaging, static renal imaging and lateral imagings of both kidneys after static renal imaging respectively. Pediatric renal volume was calculated using the improved formula length × width × thickness × 0.674, and then the renal function in per unit volume (GFR/unit volume, ml/cm3) was obtained. All statistical analysis was done with SPSS Statistics version 24.0. The renal function in per unit volume was a minimum of 1.62 ml/cm3 in left healthy kidney in static renal imaging, but the renal function in per unit volume was a maximum value of 2.20 ml/cm3 in right healthy kidney in ultrasonography. There was a strong positive correlation observed between GFR and renal volume in left healthy kidney group and left and right kidneys with mild hydronephrosis groups (r = 0.865, r = 0.872, r = 0.822). A moderate positive correlation was found between GFR and renal volume in right healthy kidney group and left and right kidneys wih severe hydronephrosis groups (r = 0.783, r = 0.542, r = 0.798). GFR in per unit volume ranged from 1.62 to 2.20 ml/cm3 in healthy kidney, and was significantly higher in right kidney as compared to in left kidney, and also decreased with the progression of hydronephrosis.

Proximal Tubule Neighborhood in AKI, CKD, and Healthy Control Kidney Tissue Using Spatial Transcriptomics

Proximal Tubule Neighborhood in AKI, CKD, and Healthy Control Kidney Tissue Using Spatial Transcriptomics

Clinically Translatable Hyperpolarized 13C Bicarbonate pH Imaging Method for Use in Prostate Cancer.

Solid tumors such as prostate cancer (PCa) commonly develop an acidic microenvironment with pH 6.5-7.2, owing to heterogeneous perfusion, high metabolic activity, and rapid cell proliferation. In preclinical prostate cancer models, disease progression is associated with a decrease in tumor extracellular pH, suggesting that pH imaging may reflect an imaging biomarker to detect aggressive and high-risk disease. Therefore, we developed a hyperpolarized carbon-13 MRI method to image the tumor extracellular pH (pHe) and prepared it for clinical translation for detection and risk stratification of PCa. This method relies on the rapid breakdown of hyperpolarized (HP) 1,2-glycerol carbonate (carbonyl-13C) via base-catalyzed hydrolysis to produce HP 13CO32-, which is neutralized and converted to HP H13CO3-. After injection, HP H13CO3- equilibrates with HP 13CO2 in vivo and enables the imaging of pHe. Using insights gleaned from mechanistic studies performed in the hyperpolarized state, we solved issues of polarization loss during preparation in a clinical polarizer system. We successfully customized a reaction apparatus suitable for clinical application, developed clinical standard operating procedures, and validated the radiofrequency pulse sequence and imaging data acquisition with a wide range of animal models. The results demonstrated that we can routinely produce a highly polarized and safe HP H13CO3- contrast agent suitable for human injection. Preclinical imaging studies validated the reliability and accuracy of measuring acidification in healthy kidney and prostate tumor tissue. These methods were used to support an Investigational New Drug application to the U.S. Food and Drug Administration. This methodology is now ready to be implemented in human trials, with the ultimate goal of improving the management of PCa.

Tubular toxicity of proteinuria and the progression of chronic kidney disease.

Proteinuria is a well-established biomarker of chronic kidney disease (CKD) and a risk predictor of associated disease outcomes. Proteinuria is also a driver of CKD progression toward end-stage kidney disease. Toxic effects of filtered proteins on proximal tubular epithelial cells enhance tubular atrophy and interstitial fibrosis. The extent of protein toxicity and the underlying molecular mechanisms responsible for tubular injury during proteinuria remain unclear. Nevertheless, albumin elicits its toxic effects when degraded and reabsorbed by proximal tubular epithelial cells. Overall, healthy kidneys excrete over 1000 individual proteins, which may be potentially harmful to proximal tubular epithelial cells when filtered and/or reabsorbed in excess. Proteinuria can cause kidney damage, inflammation and fibrosis by increasing reactive oxygen species, autophagy dysfunction, lysosomal membrane permeabilization, endoplasmic reticulum stress and complement activation. Here we summarize toxic proteins reported in proteinuria and the current understanding of molecular mechanisms of toxicity of proteins on proximal tubular epithelial cells leading to CKD progression.

Evaluation of the Effects of Long-Term Indwelling Ureteral Stents on Preserving Renal Parenchyma and Function in Patients with Ureteral Stenosis

Although ureteral stenting is a common conservative treatment for ureteral stricture, it is unclear whether a long-term indwelling ureteral stent protects the kidney against parenchymal atrophy and functional deterioration. In this study, we evaluated the changes in renal parenchymal thickness (RPT) and estimated the glomerular filtration rates (eGFR) in patients with indwelling ureteral stents for one year or more. As a control, we also evaluated changes in RPT associated with indwelling percutaneous nephrostomy (PNS) for one year or more. Polymer ureteral stents were used and replaced every three months. RPT was measured using computed tomography (CT). Totally, 69 renal units in 55 patients with baseline and follow up CT scans available were enrolled. The median follow-up period was 29 months. The etiologies of ureteral obstruction were malignant and benign disease in 27 and 28, respectively. RPT was reduced obviously in most cases. At 1 year, the median reduction rate of RPT was 17.3% in unilateral cases, which was significantly higher than that in the healthy contralateral kidney. There was a strong correlation between eGFR and total RPT including the contralateral kidney. The reduction rate of RPT in kidneys with ureteral stents including bilateral cases was also significantly higher than that in 39 renal units of 35 patients with PNS. The results of this study suggest that the long-term efficacy of indwelling ureteral stents in preserving renal function is limited. Regular imaging may be essential to evaluate the residual renal function.

A-108 Validation of Plasma Oxalate Measurement on the Roche Cobas c501

Abstract Background Measurement of plasma oxalate is important in patients with renal failure as oxalate may build up due to impaired excretion and lead to organ damage due to precipitation of calcium oxalate crystals. However, the measurement of plasma oxalate is challenging due to the low concentrations present in individuals with healthy kidney function and the pre-analytical steps needed to prevent erroneous oxalate results due to conversion from ascorbate. In order to provide improved turn-around-time for plasma oxalate testing, our objective was to develop and validate a method to measure plasma oxalate on the Roche cobas c501. Methods Samples used in the validation study included both fresh collections and residual plasma from specimens collected in lithium heparin, no-gel tubes. Samples from fresh collections were kept on ice prior to centrifugation, and then frozen if not analyzed immediately. Thawed plasma was acidified by addition of 12.1 M HCl to a pH between 2 and 3 and mixed thoroughly by vortexing. One milliliter of the acidified plasma was added to a Centrifree filter (Millipore). The samples were then centrifuged for 90 min at 1500 × g 20°C in a fixed angle rotor to remove plasma proteins. The resulting filtrate was assayed on the Roche cobas c501. The assay (Trinity Biotech) uses oxalate oxidase to produce an indamine dye through the production of hydrogen peroxide from oxalate in the sample, which is measured spectrophotometrically at 600 nm at a single time point. The analytical measuring range (AMR) was evaluated by performing serial dilutions of a high sample. Interferences from hemolysis, icterus, and lipemia were assessed at both low and high oxalate concentrations. Precision was evaluated using two QC concentrations, and patient samples with low and high concentrations of oxalate. Samples were tested ten times in a single day, or twice per day for ten days to estimate intra- and inter-precision, respectively. Spike recovery studies were used to assess method accuracy. Lastly, reference intervals were verified by assaying samples from twenty healthy volunteers. Total allowable error was ±30% or 2 µmol/L with a maximum 15%CV. Results The assay was validated to be linear across an AMR of 2 to 30 µmol/L, with an average recovery of 105% across five concentrations. The total assay imprecision was &amp;lt;15%. Initial spike recovery studies across the AMR showed an average recovery of 99.4% (n = 12), with a range of 76.6 to 132.4%. In a mixing study, hemolyzed and lipemic sample recovery was on average 82.1% and 76.1% respectively, which was low, but acceptable. Samples mixed with icteric specimens demonstrated unacceptably low recovery (average of 64.1%). The reference interval of &amp;lt;2 µmol/L was successfully verified as all twenty healthy volunteers had results &amp;lt;2 µmol/L. Conclusion Initial validation studies support the clinical utility of the newly developed method. Plasma oxalate methods are documented to have significant inter-method variability and variable recovery, which is hypothesized to be due to variation at the filtration step. This semi-automated assay will require less technologist time and will reduce the possibility for human error affecting the result.

Acute Kidney Injury (AKI) in COVID-19: In silico Identification of LncRNA-MiRNA-Gene Networks and Key Transcription Factors.

Acute kidney injury (AKI) accounts for up to 29% of severe COVID-19 cases and increases mortality among these patients. Viral infections participate in the pathogenesis of diseases by changing the expression profile of normal transcriptome. This study attempts to identify LncRNA-miRNA-gene and TF-gene networks as gene expression regulating networks in the kidney tissues of COVID-19 patients. In this analysis, four kidney libraries from the GEO repository were considered. To conduct the preprocessing, Deseq2 software in R was used for the purpose of data normalization and log2 transformation. In addition, pre- and post-normalization, PCA and box plots were developed using ggplot2 software in R for quality control. The expression profiles of the kidney samples of COVID-19 patients and control individuals were compared using DEseq2 software in R. The considered significance thresholds for DEGs were Adj P value < 0.05 and |logFC| >2. Then, to predict molecular interactions in lncRNA-miRNA-gene networks, different databases, including DeepBase v3.0, miRNATissueAtlas2, DIANA-LncBase v3, and miRWalk, were used. Furthermore, by employing ChEA databases, interactions at the TF-Gene level were obtained. Finally, the obtained networks were plotted using Stringdb and Cytoscape v8. Results obtained from the comparison of the post-mortem kidney tissue samples of the COVID-19 patients with the healthy kidney tissue samples showed significant changes in the expression of more than 2000 genes. In addition, predictions regarding the miRNA-gene interaction network based on DEGs obtained from this meta-analysis showed that 11 miRNAs targeted the obtained DEGs. Interestingly, in the kidney tissue, these 11 miRNAs interacted with LINC01874, LINC01788, and LINC01320, which have high specificity for this tissue. Moreover, four transcription factors of EGR1, SMAD4, STAT3, and CHD1 were identified as key transcription factors regulating DEGs. Taken together, the current study showed several dysregulated genes in the kidney of patients affected with COVID-19. This study suggests lncRNA-miRNA-gene networks and key TFs as new diagnostic and therapeutic targets for experimental and preclinical studies.