Assessment of proteinuria

A fluorescent "Turn-ON" probe with rapid and differential response to HSA and BSA: quantitative detection of HSA in urine

The present study provides insight into the differential response of a benzimidazole-malononitrile fluorescent "Turn-ON" probe on interaction with two structurally similar proteins, BSA and HSA. Compound 6 shows more sensitivity towards the two SAs, which is completely lost in the case of compound 7, synthesized by substitution on 6. The aggregates of compound 6 show absorption maxima at 385 nm and weak emission maxima at 565 nm. Compound 6 forms a new emission band at 475 nm on gradual addition of BSA (200 μM) along with a slight increase in the emission band at 565 nm. However, on addition of HSA (50 μM), a new band at 475 nm is formed. In contrast to BSA, in the case of HSA, 50% quenching is observed in the emission band of compound 6 at 565 nm. The new band formed on the interaction of 6 with BSA shows four-fold more enhancement compared to HSA. Furthermore, the mechanism of interaction of 6 with serum albumin has been investigated through lifetime-fluorescence analysis, site-selective drug experiments, dynamic light scattering, FE-SEM, FT-IR, etc. Molecular docking studies and site marker drug displacement experiments reveal differential interactions of 6 towards the two structurally similar proteins. Aggregates of 6 with an average hydrodynamic size of 100-190 nm are disassembled on adding BSA and HSA, and the size of the serum albumin and 6 complex decreases to 10-20 nm, revealing the ligand's encapsulation in the serum albumin cavity. Practical applicability for the quantitative detection of HSA in human urine samples is also demonstrated. The high binding affinity, sensitivity, selectivity and differential response of probe 6 towards two serum albumins (HSA and BSA) and significant quantification of HSA in urine samples shows the potential ability of this probe in medical applications.

Molecular mechanisms underlying cisplatin-induced nephrotoxicity and the potential ameliorative effects of essential oils: A comprehensive review

Since the Middle Ages, essential oils (EO) have been widely used for bactericidal, virucidal, fungicidal, insecticidal, medicinal and cosmetic applications, nowadays in pharmaceutical, agricultural and food industries. Recently, EO have emerged as promising adjuvant therapies to mitigate the toxicities induced by anti - cancerous drugs; among them cisplatin induced renal damage amelioration remain remarkable. Cisplatin (cis-diaminedichloroplatinum II, CDDP) is renowned as one of the most effective anti-neoplastic agents, widely used as a broad-spectrum anti-tumor agent for various solid tumors. However, its clinical use is hampered by several side effects, notably nephrotoxicity and acute kidney injury, which arise from the accumulation of CDDP in the proximal tubular epithelial cells (PTECs). To better understand and analyze the molecular mechanisms of CDDP-induced renal damage, it is crucial to investigate potential interventions to protect against cisplatin-mediated nephrotoxicity. These EO have shown the ability to counteract oxidative stress, reduce inflammation, prevent apoptosis, and exert estrogenic effects, all contributing to renal protection. In this review, we have made an effort to summarize the molecular mechanisms and exploring new interventions by which we can pave the way for safer and more effective cancer management in the future.

Proteinuria selectivity index in renal disease

One of the main barriers to early detection and subsequent prevention of kidney diseases is the accessibility and feasibility of testing, especially in urine research. The proteinuria selectivity index (PSI or SI) is a method used to assess changes in glomerular permeability in glomerular diseases. It describes the pattern of proteinuria by comparing the clearance rates of large molecular proteins and transferrin, categorizing it as selective or non-selective. PSI is widely applied for kidney disease classification, prediction of corticosteroid efficacy, and prognosis. Herein, we reviewed the clinical applications and recent advancements of PSI in glomerular diseases, compared it with commonly used renal function biomarkers, and discussed the future research directions for PSI as a potential predictive marker for response to specific biologics.

Withstanding the test of time: Morning versus afternoon/evening urine protein-to-creatinine ratios in preeclampsia

OBJECTIVE

There are mixed findings regarding time preference for measuring spot urine protein to creatinine ratios (UPCR) in renal patients but no such literature among pregnant patients. We compare AM versus PM measurements for UPCR among pregnant patients with preeclampsia.

STUDY DESIGN

This retrospective study included 163 patients diagnosed with preeclampsia. Laboratory tests of UPCR, urine specificity gravity, and uric acid were collected for these patients during the morning (AM) 12:00 AM (00:00) through 11:59 AM (11:59) and afternoon/evening (PM) 12:00 PM (12:00) through 11:59 PM (23:59).

MAIN OUTCOME MEASURES

Outcomes were UPCR percentages indicative of preeclampsia, UPCR median values, abnormal uric acid, and normal urine specific gravity indicative of a quality sample for measuring UPCR.

RESULTS

UPCR ≥ 0.3 indicative of preeclampsia significantly differed (p < 0.001) where the AM group (76.7 %) had a greater percentage than the PM group (52.8 %). Median UPCR significantly differed (p < 0.001) where the AM group had a greater median (0.44) than the PM group (0.32). None of the uric acid or urine specific gravity comparisons significantly differed between the AM and PM groups. Similar patterns occurred for subgroups of those with hypertension, nulliparous, and preeclampsia with severe features.

CONCLUSION

We found that UPCR had greater median values and more values indicative of preeclampsia for AM measurements than PM measurements. Clinicians who use spot urine measurements and not 24-hour urine measurements should preferably measure UPCR in the AM rather than the PM.

Urinary Liver-Type Fatty Acid Binding Protein, a Biomarker for Disease Progression, Dialysis and Overall Mortality in Chronic Kidney Disease

Chronic kidney disease (CKD) is a major public health concern with an increasing proportion of sufferers progressing to renal replacement therapy (RRT). Early identification of those at risk of disease progression could be key in improving outcomes. We hypothesise that urinary liver-type fatty acid binding protein (uL-FABP) may be a suitable biomarker for CKD progression and can add value to currently established biomarkers such as the urinary protein-to-creatinine ratio (uPCR). A total of 583 participants with CKD 1-5 (not receiving renal replacement therapy) entered a 2 yr prospective longitudinal study. UPCR and uL-FABP were measured at baseline and CKD progression was defined as either (i) a decline in eGFR of >5 mL/min/1.73 m2 or an increase in serum creatinine by 10% at 1 yr; (ii) a decline in eGFR of >6 mL/min/1.73 m2 or an increase in serum creatinine by 20% at 2 yrs; or (iii) the initiation of RRT. A combined outcome of initiating RRT or death was also included. Approximately 40% of participants showed CKD progression. uL-FABP predicted CKD progression at both years 1 and 2 (OR 1.01, p < 0.01). Sensitivity and specificity were comparable to those of uPCR (AUC 0.623 v 0.706) and heat map analysis suggested that uL-FABP in the absence of significant proteinuria can predict an increase in serum creatinine of 10% at 1 yr and 20% at 2 yrs. The risk of the combined outcome of initiating RRT or death was 23% higher in those with high uL-FABP (p < 0.01) independent of uPCR. uL-FABP appears to be a highly sensitive and specific biomarker of CKD progression. The use of this biomarker could enhance the risk stratification of CKD and its progression and should be assessed further.

Development of a High-Accuracy, Low-Cost, and Portable Fluorometer with Smartphone Application for the Detection of Urinary Albumin towards the Early Screening of Chronic Kidney and Renal Diseases

This study presents the development of a portable fluorometer with a smartphone application designed to facilitate the early screening of chronic kidney and renal diseases by enabling the sensitive detection of urinary albumin. Utilizing a fluorescence-based aptasensor, the device achieved a linear calibration curve (0.001-1.5 mg/mL) with a linearity of up to 0.98022 and a detection limit of 0.203 µg/mL for human serum albumin (HSA). The analysis of 130 urine samples demonstrated comparable performance between this study's fluorometer, a commercial fluorometer, and the standard automated method. These findings validate the feasibility of the portable fluorometer and aptasensor combination as a reliable instrument for the sensitive and specific measurement of HSA in urine samples. Moreover, the fluorometer's portability offers potential applications in portable point-of-care testing, enhancing its utility in clinical settings for early disease screening.

Albumin-to-protein ratio in spot urine samples for analysis of proteinuria selectivity in chronic kidney disease

INTRODUCTION

The albumin-to-creatinine ratio and total protein-to-creatinine ratio in spot urine samples have already been validated as surrogates for 24-hour albuminuria and proteinuria measurements. Thus, we hypothesized that the type of proteinuria, detected by the electrophoretic pattern of 24-hour urine, could be predicted by the simple proportion of albumin in the total urine protein content, using the albumin-to-protein ratio (APR). Our study sought to validate the use of APR as a cheaper substitute for urinary protein electrophoresis (UPE).

METHODS

Using different mathematical models, we compared, the albumin fraction in 24-hour urine samples by electrophoresis and the APR ratio in spot samples from 42 outpatients with chronic kidney disease (CKD).

RESULTS

A strong log-order correlation r = 0.84 (0.75-0.92; 95% CI, p = 0.001) was observed between APR and the albumin fraction in the UPE.

CONCLUSION

The APR can substitute electrophoresis in CKD outpatients.

Probability of chronic kidney disease and associated risk factors in Chinese adults: a cross-sectional study of 9 million Chinese adults in the Meinian Onehealth screening survey

Background

Chronic kidney disease (CKD) is an increasing global health problem, but little is known about the age- and sex-specific prevalence of CKD and the associated risk factors in low- and middle-income populations. We examined the age- and sex-specific prevalence of CKD and the associated risk factors in a population-based study of 9 million Chinese adults.

Methods

The study involved a cross-sectional survey of 9 461 631 adults, >18 years of age, who were recruited in 2017 from 31 provinces in the Meinian Onehealth screening survey. All participants had plasma creatinine measured by standard methods and CKD was defined if the estimated glomerular filtration rate (eGFR) was <60 ml/min/1.73 m².

Results

Overall, among 9.5 million adults [mean age 41 years (standard deviation 13.1)], 88 271 (1.26%) had CKD. The prevalence rate of CKD was 1.20%, 0.04% and 0.02% for stage 3, 4 and 5, respectively. After adjustment for the proportion and prevalence of urban and rural areas, the overall prevalence rate of CKD was 1.07%, indicating that ∼14 million Chinese adults have CKD. The prevalence of CKD increased 3-fold for each 10-year increment in age (1.15%, 3.05% and 13.02% at age 50-59, 60-69 and >70 years, respectively) and was 1.8-fold higher in women than men. The prevalence of CKD was higher in the Southwest region {1.68% [95% confidence interval (CI) 1.12-2.24]} but lower in the Northwest region [0.84% (95% CI 0.61-1.07)] than other regions. If proteinuria is also used as a diagnostic criterion, the prevalence rate increased to 2.16%. Stepwise logistic regression analysis demonstrated that body mass index; history of hypertension, cardiovascular disease or diabetes; and levels of systolic blood pressure, triglycerides, fasting glucose and uric acid were independent risk factors for CKD.

Conclusion

CKD is an important public health problem in Chinese adults and this study highlights the need for public health strategies to detect and reduce modifiable risk factors for prevention of CKD.

Razão albumina/proteína em amostras isoladas de urina para análise da seletividade de proteinúria na doença renal crônica

Resumo Introdução: A utilização da razão albumina/creatinina e da razão proteína total/creatinina em amostras isoladas de urina já foram validadas como substitutos para a albuminúria e proteinúria em 24 horas. Assim, nossa hipótese é que o tipo de proteinúria, dado pelo padrão eletroforético da urina de 24 horas, poderia ser previsto pela simples proporção de albumina no conteúdo total de proteínas na urina, utilizando a razão albumina/proteína (RAP). O presente estudo procurou validar o uso da RAP como um substituto mais prático e de menor custo da eletroforese de proteínas urinárias (EPU). Métodos: Foram utilizados diferentes modelos matemáticos a fim de comparar a fração de albumina pela eletroforese em amostras de urina de 24 horas e a RAP em amostras isoladas em 42 pacientes ambulatoriais com doença renal crônica. Resultados: Foi observada uma forte correlação logarítmica r = 0,84 (0,75–0,92; 95% CI, p = 0,001) entre a RAP e a fração de albumina pela EPU. Conclusão: A RAP pode substituir a eletroforese urinária em pacientes renais crônicos ambulatoriais.

Novel Biomarkers of Kidney Disease in Advanced Heart Failure: Beyond GFR and Proteinuria

PURPOSE

Kidney disease is a common finding in patients with heart failure and can significantly impact treatment decisions and outcomes. Abnormal kidney function is currently determined in clinical practice using filtration markers in the blood to estimate glomerular filtration rate, but the manifestations of kidney disease in the setting of heart failure are much more complex than this. In this manuscript, we review novel biomarkers that may provide a more well-rounded assessment of kidney disease in patients with heart failure.

RECENT FINDINGS

Galectin-3, ST2, FGF-23, suPAR, miRNA, GDF-15, and NAG may be prognostic of kidney disease progression. L-FABP and suPAR may help predict acute kidney injury (AKI). ST2 and NAG may be helpful in diuretic resistance. Several biomarkers may be useful in determining prognosis of long-term kidney disease progression, prediction of AKI, and development of diuretic resistance. Further research into the mechanisms of kidney disease in heart failure utilizing many of these biomarkers may lead to the identification of therapeutic targets.

A 90-Day Safety Study of Meat from MSTN and FGF5 Double-Knockout Sheep in Wistar Rats

MSTN and FGF5 gene knockout sheep generated by the CRISPR/Cas9 system exhibit the ‘double-muscle’ phenotype, and increased density and length of hairs, providing valuable new breeding material. In a previous study, we obtained MSTN and FGF5 double-knockout sheep of significant breeding value. In this study, we carried out a 90-day feeding study in Wistar rats to assess the safety of genome-edited mutton. Seven rat groups with 10 females and 10 males per group were fed different concentrations (3.75%, 7.5%, and 15%) of double-knockout mutton or wild-type mutton in a conventional commercial diet for 90 days. At the end of the feeding, routine urine and blood tests and measurements of blood biochemical indicators were performed. Furthermore, the major organs of each group of rats were weighed and examined histopathologically. Although there were significant differences among the groups in some parameters, all values were within the normal ranges. Therefore, the 90-day rat feeding study showed that the meat from MSTN and FGF5 double-knockout sheep did not have any long-term adverse effects on rat health. This study also provides valuable reference information for assessing the safety of meat from animals with knockout of multiple genes.

Biomarkers for Detecting Kidney Dysfunction in Type-2 Diabetics and Diabetic Nephropathy Subjects: A Case-Control Study to Identify Potential Biomarkers of DN to Stratify Risk of Progression in T2D Patients

INTRODUCTION

Currently there are no biomarkers that are predictive of when patients with type-2 diabetes (T2D) will progress to more serious kidney disease i.e., diabetic nephropathy (DN). Biomarkers that could identify patients at risk of progression would allow earlier, more aggressive treatment intervention and management, reducing patient morbidity and mortality.

MATERIALS AND METHODS

Study participants (N=88; control n=26; T2D n=32; DN n=30) were recruited from the renal unit at Antrim Area Hospital, Antrim, UK; Whiteabbey Hospital Diabetic Clinic, Newtownabbey, UK; Ulster University (UU), Belfast, UK; and the University of the Third Age (U3A), Belfast, UK; between 2019 and 2020. Venous blood and urine were collected with a detailed clinical history for each study participant.

RESULTS

In total, 13/25 (52.0%) biomarkers measured in urine and 25/34 (73.5%) biomarkers measured in serum were identified as significantly different between control, T2D and DN participants. DN patients, were older, smoked more, had higher systolic blood pressure and higher serum creatinine levels and lower eGFR function. Serum biomarkers significantly inversely correlated with eGFR.

CONCLUSION

This pilot-study identified several serum biomarkers that could be used to predict progression of T2D to more serious kidney disease: namely, midkine, sTNFR1 and 2, H-FABP and Cystatin C. Our results warrant confirmation in a longitudinal study using a larger patient cohort.

Urinary IgG, serum CX3CL1 and miRNA-152-3p: as predictors of nephropathy in Egyptian type 2 diabetic patients

The purpose of this study was to assess the role of urinary IgG, serum CX3CL1 and miRNA 152-3p levels as predictors of nephropathy in type 2 Egyptian diabetic patients. Sixty type 2 diabetic patients and twenty healthy controls were enrolled in a cross-sectional study. Then they were grouped into: three groups based upon urine albumin excretion (UAE). The expression of miRNA 152-3p in serum was measured using quantitative polymerase chain reaction (RTq-PCR). Serum CX3CL1 and urinary IgG concentrations were measured by ELISA. RTq-PCR revealed that serum miRNA-152-3p levels in patients were significantly higher than in controls. There was significant differences between group with normoalbuminuria and groups with diabetic nephropathy DN as regard to age, duration of nephropathy, Albumin/Creatinine ratio (A/C ratio), creatinine, urine IgG, CX3CL1 and HbA1c. In diabetic patients, there was a significant positive correlation between miRNA-152-3p levels and disease duration only as well as significant positive correlations between urinary IgG levels and age, disease duration, serum creatinine, A/C ratio, and urea. Positive correlation between serum fractalkine CX3CL1 level and age, duration of disease, urea, creatinine, A/C ratio, HbA1C and IgG in patient with DN. Serum CX3CL1 level, urinary IgG were significantly increased with the progress of nephropathy so these integrated biomarkers could be used as good predictors for early identification of nephropathy. But miRNA- 152-3p has inadequate prognostic indicator for ESRD progression.

Renal surgery for kidney cancer: is preoperative proteinuria a predictor of functional and survival outcomes after surgery? A systematic review of the literature

INTRODUCTION

Proteinuria is considered both a known marker for the severity of Chronic Kidney Disease (CKD) and a robust predictor of future renal function and cardiovascular morbidity and mortality in a general population. The urological community has long overlooked proteinuria as a marker of renal function. Recently, the American Urological Association (AUA) clinical practice guideline addressed this issue and suggested introducing proteinuria assessment prior to kidney cancer surgery. The aim of this systematic review was to provide evidence of proteinuria as a predictor of renal function impairment and survival outcomes after kidney surgery for renal tumors.

EVIDENCE ACQUISITION

A systematic search was performed by using three search engines (PubMed, Embase®, and Web of Science) from January 2010 to November 2020. Study selection followed the PRISMA guidelines. After screening, ten articles and abstracts fully compatible with the PICOS were included in this systematic review.

EVIDENCE SYNTHESIS

Overall, a total of 11,705 patients who underwent partial nephrectomy (PN) or radical nephrectomy (RN) were analyzed. When used as a binomial variable, proteinuria prior to surgery was detected from 10% to 33% of patients. Relying on both proteinuria and estimated glomerular filtration rate (eGFR) in the assessment of renal function yielded up to 33% higher rates of patients with preoperative renal impairment. Moreover, proteinuria increased the risk of long-term renal impairment after PN and RN as well as patients with preoperative proteinuria undergoing PN exhibited a greater risk of postoperative acute kidney injury (AKI). Among eligible studies, proteinuria was associated with diabetes, obesity, metabolic syndrome, hypertension and cardiovascular disease. Finally, proteinuria was an independent predictor of overall mortality, but not of cancer-specific mortality.

CONCLUSIONS

Proteinuria yields a prognostic power beyond that provided by estimated glomerular filtration rate (eGFR) among patients undergoing renal cancer surgery, supporting its introduction in the preoperative assessment of renal function. However, well-designed multicentre prospective studies would be necessary to corroborate these results and provided urological community with high-grade recommendation for clinical practice.

Polydopamine-based quantitation of albuminuria for the assessment of kidney damage

Proteinuria is considered indicative of kidney damage that can be related to various adverse outcomes. Nowadays, there is a huge demand for routine urine screening methods to assess health risks in clinical setting without expensive procedures and long pretreatment of the sample. To address this issue, a polydopamine-based colorimetric assay to determine urinary albumin concentration in real samples is proposed here. The core of this approach relies on the established competitive adsorption of polydopamine film and human serum albumin onto the polystyrene surface of ELISA plates. Herein, we investigated the influence of temperature and the Tris-HCl buffer concentration on the polydopamine film growth. The absorbance of polydopamine film, after 24 h at 25 °C, decreases with the increase of HSA concentration, allowing the selective detection of HSA down to 0.036 ± 0.001 g L^-1 in untreated urine. This simple and low-cost bioanalytical assay exhibited very good reproducibility, %CV_mean = 2 in human urine, and was superior in terms of analytical performances to some standard methods available on the market, especially in comparison to the Bradford assay, for early screening and assessment of kidney damage.

Review: Detection and quantification of proteins in human urine

Extensive medical research showed that patients, with high protein concentration in urine, have various kinds of kidney diseases, referred to as proteinuria. Urinary protein biomarkers are useful for diagnosis of many health conditions - kidney and cardio vascular diseases, cancers, diabetes, infections. This review focuses on the instrumental quantification (electrophoresis, chromatography, immunoassays, mass spectrometry, fluorescence spectroscopy, the infrared spectroscopy, and Raman spectroscopy) of proteins (the most of all albumin) in human urine matrix. Different techniques provide unique information on what constituents of the urine are. Due to complex nature of urine, a separation step by electrophoresis or chromatography are often used for proteomics study of urine. Mass spectrometry is a powerful tool for the discovery and the analysis of biomarkers in urine, however, costs of the analysis are high, especially for quantitative analysis. Immunoassays, which often come with fluorescence detection, are major qualitative and quantitative tools in clinical analysis. While Infrared and Raman spectroscopies do not give extensive information about urine, they could become important tools for the routine clinical diagnostics of kidney problems, due to rapidness and low-cost. Thus, it is important to review all the applicable techniques and methods related to urine analysis. In this review, a brief overview of each technique's principle is introduced. Where applicable, research papers about protein determination in urine are summarized with the main figures of merits, such as the limit of detection, the detectable range, recovery and accuracy, when available.

Comparison of Two Different Semiquantitative Urinary Dipstick Tests with Albumin-to-Creatinine Ratio for Screening and Classification of Albuminuria According to KDIGO. A Diagnostic Test Study

Background: Semiquantitative dipstick tests are utilized for albuminuria screening. Methods: In a prospective cross-sectional survey, we analyzed the diagnostic test validity of the semiquantitative colorimetric indicator-dye-based Combur9-Test^® and the albumin-specific immunochromatographic assay Micral-Test^® for the detection of albuminuria, the distribution of the semiquantitative measurements within the albuminuria stages according to KDIGO, and the utility for albuminuria screening compared with an albumin-to-creatinine ratio (ACR) in a walk-in population. Results: In 970 subjects, albuminuria (≥30 mg/g) was detected in 12.7% (95% CI 85.6–96.3%) with the ACR. Sensitivity was 82.9% (95% CI 75.1–89.1%) and 91.9% (95% CI 88.7–96.9%) and specificity 71.5% (95% CI 68.4–74.6%) and 17.5% (95% CI 15.0–20.2%) for the Combur9-Test^® and Micral-Test^®, respectively. Correct classification to KDIGO albuminuria stages A2/A3 with the Combur9-Test^® was 15.4%, 51.4%, and 87.9% at cut-offs of 30, 100, and ≥300 mg/dL, and with the Micral-Test^® it was 1.8%, 10.5%, and 53.6% at cut-offs of 2, 5, and 10 mg/dL, respectively. Overall, disagreement to KDIGO albuminuria was seen in 27% and 73% with the Combur9-Test^® and Micral-Test^®, respectively. From the total population, 62.5% and 15.3% were correctly ruled out and 2.2% and 1% were missed as false-negatives by the Combur9-Test^® and Micral-Test^®, respectively. Conclusion: Compared to the Combur9-Test^®, the utility of the Micral-Test^® is limited, because the fraction of correctly ruled out patients is small and a large proportion with a positive Micral-Test^® require a subsequent ACR conformation test.

Development and validation of hybrid Brillouin-Raman spectroscopy for non-contact assessment of mechano-chemical properties of urine proteins as biomarkers of kidney diseases

BACKGROUND

Proteinuria is a major marker of chronic kidney disease (CKD) progression and the predictor of cardiovascular mortality. The rapid development of renal failure is expected in those patients who have higher level of proteinuria however, some patients may have slow decline of renal function despite lower level of urinary protein excretion. The different mechanical (visco-elastic) and chemical properties, as well as the proteome profiles of urinary proteins might explain their tubular toxicity mechanism. Brillouin light scattering (BLS) and surface enhanced Raman scattering (SERS) spectroscopies are non-contact, laser optical-based techniques providing visco-elastic and chemical property information of probed human biofluids. We proposed to study and compare these properties of urinary proteins using BLS and SERS spectroscopies in nephrotic patient and validate hybrid BLS-SERS spectroscopy in diagnostic of urinary proteins as well as their profiling. The project ultimately aims for the development of an optical spectroscopic sensor for rapid, non-contact monitoring of urine samples from patients in clinical settings.

METHODS

BLS and SERS spectroscopies will be used for non-contact assessment of urinary proteins in proteinuric patients and healthy subjects and will be cross-validated by Liquid Chromatography-Mass Spectrometry (LC-MS). Participants will be followed-up during the 1 year and all adverse events such as exacerbation of proteinuria, progression of CKD, complications of nephrotic syndrome, disease relapse rate and inefficacy of treatment regimen will be registered referencing incident dates. Associations between urinary protein profiles (obtained from BLS and SERS as well as LC-MS) and adverse outcomes will be evaluated to identify most unfavored protein profiles.

DISCUSSION

This prospective study is focused on the development of non-contact hybrid BLS - SERS sensing tool and its clinical deployment for diagnosis and prognosis of proteinuria. We will identify the most important types of urine proteins based on their visco-elasticity, amino-acid profile and molecular weight responsible for the most severe cases of proteinuria and progressive renal function decline. We will aim for the developed hybrid BLS - SERS sensor, as a new diagnostic & prognostic tool, to be transferred to other biomedical applications.

TRIAL REGISTRATION

The trial has been approved by ClinicalTrials.gov (Trial registration ID NCT04311684). The date of registration was March 17, 2020.

Revisiting Experimental Models of Diabetic Nephropathy

Diabetes prevalence is constantly increasing and, nowadays, it affects more than 350 million people worldwide. Therefore, the prevalence of diabetic nephropathy (DN) has also increased, becoming the main cause of end-stage renal disease (ESRD) in the developed world. DN is characterized by albuminuria, a decline in glomerular filtration rate (GFR), hypertension, mesangial matrix expansion, glomerular basement membrane thickening, and tubulointerstitial fibrosis. The therapeutic advances in the last years have been able to modify and delay the natural course of diabetic kidney disease (DKD). Nevertheless, there is still an urgent need to characterize the pathways that are involved in DN, identify risk biomarkers and prevent kidney failure in diabetic patients. Rodent models provide valuable information regarding how DN is set and its progression through time. Despite the utility of these models, kidney disease progression depends on the diabetes induction method and susceptibility to diabetes of each experimental strain. The classical DN murine models (Streptozotocin-induced, Akita, or obese type 2 models) do not develop all of the typical DN features. For this reason, many models have been crossed to a susceptible genetic background. Knockout and transgenic strains have also been created to generate more robust models. In this review, we will focus on the description of the new DN rodent models and, additionally, we will provide an overview of the available methods for renal phenotyping.

Biochemical evaluation of kidney disease

Different biochemical markers exist in both blood and urine for assessing renal function. Most of these biomarkers have advantages and limitations associated with their use, which is important to consider when ordering and utilising them in the clinical setting. The ideal marker should be able to detect acute kidney injury (AKI) at the onset and be used for the diagnosis and ongoing monitoring and management of kidney disease. The search for such a marker is ongoing, as all potential candidates thus far are associated with certain limitations. This article will attempt to compare and contrast established and emerging kidney disease markers.

Acute kidney injury after burn surgery: Preoperative neutrophil/lymphocyte ratio as a predictive factor

BACKGROUND

Severe inflammation and acute kidney injury (AKI) are serious adverse events after burn injuries. The neutrophil/lymphocyte ratio (NLR) is a marker of inflammation. We evaluated the independent risk factors for postoperative AKI, including NLR, in burn-injured patients.

METHODS

The preoperative, intraoperative, and postoperative variables of 473 burn-injured patients were collected. The risk factors for AKI after burn surgery were evaluated using univariate and multivariate logistic regression analyses. The receiver operating characteristic (ROC) curve analysis of preoperative NLR was performed. The 3-month mortality after surgery was also compared between AKI and non-AKI groups using Kaplan-Meier analysis with a log-rank test.

RESULTS

Postoperative AKI occurred in 71 of 473 (15.0%) burn patients. The total body surface area burned (odds ratio (OR), 1.013; 95% confidence interval (CI), 1.001-1.026; P = 0.037), inhalation injury (OR, 1.821; 95% CI, 1.008-3.292; P = 0.047), and preoperative NLR (OR, 1.094; 95% CI, 1.064-1.125; P < 0.001) were risk factors for AKI after surgery. The area under the ROC curve was 0.767, with an optimal cut-off value of 11.7. Moreover, the 3-month mortality after surgery was significantly higher in the AKI group than in the non-AKI group (49.3% vs 14.9%, P < 0.001).

CONCLUSION

Total body surface area burned, inhalation injury, and preoperative NLR are risk factors for AKI after burn surgery, which is associated with early postoperative mortality. Preoperative NLR can provide useful information for the early detection of postoperative AKI and subsequent mortality in burn-injured patients.

Kidney Smartphone Diagnostics

Here we present a method for a mobile point-of-care (POC) testing of urinary albumin concentration, a biomarker of kidney damage and cardiovascular disease. The self-testing strips are meant to be interpreted by means of a smartphone application. The limits of detection range from 0.15 to 0.30 g/L urinary albumin, though results below 0.10 g/L are presented in a quantitative manner and estimates larger than this threshold are shown as categorical variables in a qualitative manner for increasing urinary albumin concentrations. Calibrated once under standard conditions, the app enables the user to capture problem samples and calculate the corresponding concentration. Negative and positive findings must be interpreted, taking into account the inherent limitations of the method, and professional health advice must be requested for diagnostic considerations. Acknowledgment of the association between early life nutrition and long-term renal health and the adoption of preventive strategies targeting high-risk groups is key for the reduction of the burden of chronic kidney disease on a global scale.

Estimated glomerular filtration rate and albuminuria in Korean population evaluated for cardiovascular risk

PURPOSE

This study's purpose was to examine established cardiovascular risk prediction model scores for their associations with albuminuria and estimated glomerular filtration rate (eGFR) in Korean population.

METHODS

We calculated the 10-year atherosclerotic cardiovascular disease (ASCVD) risk estimated score, Korean coronary heart disease risk prediction score (KRS), and the Adult Treatment Panel (ATP) III risk score for 9733 South Koreans, aged 40-79 years, who were not diagnosed with stroke, angina pectoris, or myocardial ischemia using data from the 2011-2013 Korea National Health and Nutrition Examination Survey.

RESULTS

The associations between cardiovascular risk model scores and the urine albumin-to-creatinine ratio (UACR) and eGFR tended to be stronger for the ASCVD risk score than for the other risk scores. The area under the receiver operating characteristic curve for increased albuminuria (UACR ≥ 30 mg/g) and decreased eGFR (<60 mL/min/1.73 m(2)) was significantly higher for the ASCVD risk score than for the ATP III risk score and the KRS (except for increased albuminuria in women).

CONCLUSIONS

The ASCVD risk score had a stronger relationship with and better predicted albuminuria and eGFR than did the KRS and ATP III risk score.

Monitoring for proteinuria in patients with type 2 diabetes mellitus

OBJECTIVE

The UK National Institute for Health and Care Excellence (NICE) guideline on diabetes recommends at least annual monitoring of patients with type 2 diabetes mellitus (T2DM) for proteinuria. To date, little has been published on the frequency of proteinuria monitoring in T2DM, and its association with risk factors for renal complications. We aimed to describe proteinuria monitoring in patients with T2DM.

DESIGN

This study identified patients with T2DM aged 40 years or older with the first antidiabetic drug use in 2007-2012 (cohort entry) in the UK Clinical Practice Research Datalink. At least 1 year of registration before and after cohort entry was required. A test was considered undertaken if a medical or laboratory code indicated a urinary albumin or protein test. The percentage of patients with at least one test performed was obtained in 1 year after cohort entry and any time during follow-up. A Cox proportional hazards model was used to estimate the HRs of patients having the first screening test while adjusting for baseline covariates.

RESULTS

65 790 patients (mean age 63.0 years, men 57.5%, mean follow-up 41.0 months) were included, of whom 49 707 (75.6%) patients had at least one test in 1 year after antidiabetic drug initiation and 59 400 (90.3%) had at least one test any time during follow-up. Proteinuria monitoring decreased with time since initiation of antidiabetic drug therapy and with number of treatment changes and was independently associated with age, sex, smoking status, and year of antidiabetic drug initiation. 12.3% of patients with T2DM tested had a positive proteinuria test for the first screening performed in 1 year after initiation of antidiabetic drug therapy.

CONCLUSIONS

The findings suggested suboptimal compliance with the NICE guideline on proteinuria monitoring in patients with T2DM and that level of monitoring appeared to depend on multiple clinical factors.

Use and isolation of urinary exosomes as biomarkers for diabetic nephropathy

Diabetes represents a major threat to public health and the number of patients is increasing alarmingly in the global scale. Particularly, the diabetic kidney disease (nephropathy, DN) together with its cardiovascular complications cause immense human suffering, highly increased risk of premature deaths, and lead to huge societal costs. DN is first detected when protein appears in urine (microalbuminuria). As in other persisting proteinuric diseases (like vasculitis) it heralds irreversible damage of kidney functions up to non-functional (end-stage) kidney and ultimately calls for kidney replacement therapy (dialysis or kidney transplantation). While remarkable progress has been made in understanding the genetic and molecular factors associating with chronic kidney diseases, breakthroughs are still missing to provide comprehensive understanding of events and mechanisms associated. Non-invasive diagnostic tools for early diagnostics of kidney damage are badly needed. Exosomes - small vesicular structures present in urine are released by all cell types along kidney structures to present with distinct surface assembly. Furthermore, exosomes carry a load of special proteins and nucleic acids. This "cargo" faithfully reflects the physiological state of their respective cells of origin and appears to serve as a new pathway for downstream signaling to target cells. Accordingly, exosome vesicles are emerging as a valuable source for disease stage-specific information and as fingerprints of disease progression. Unfortunately, technical issues of exosome isolation are challenging and, thus, their full potential remains untapped. Here, we review the molecular basis of exosome secretion as well as their use to reveal events along the nephron. In addition to novel molecular information, the new methods provide the needed accurate, personalized, non-invasive, and inexpensive future diagnostics.

Overflow proteinuria as a manifestation of unrecognized polymyositis

Polymyositis is a rare and gradually progressive autoimmune disease of skeletal muscle. Two main types of renal involvement have been described: acute tubular necrosis related to rhabdomyolysis and glomerulonephritis. However, cases of overflow proteinuria related to polymyositis have rarely been reported. Herein, we report a case of a 41-year-old male who presented with edema of both lower extremities. Laboratory studies revealed elevated creatine phosphokinase level, hypoalbuminemia, and a moderate amount of proteinuria, although albuminuria was not dominant. Urine electrophoresis showed an abnormally restricted zone in the β-fraction, which suggested overflow proteinuria of non-glomerular origin. Despite intravenous hydration, his serum creatine phosphokinase level did not decrease and his symptoms did not improve. Electromyography showed myopathy, and muscle biopsy revealed findings consistent with polymyositis. After corticosteroid therapy, his creatine phosphokinase level and proteinuria decreased and his clinical symptoms improved. This case demonstrates an atypical presentation of polymyositis manifested by overflow proteinuria.

Measurement of renal function in patients with chronic kidney disease

Chronic kidney disease affects millions of people worldwide and is associated with an increased morbidity and mortality as a result of kidney failure and cardiovascular disease. Accurate assessment of kidney function is important in the clinical setting as a screening tool and for monitoring disease progression and guiding prognosis. In clinical research, the development of new methods to measure kidney function accurately is important in the search for new therapeutic targets and the discovery of novel biomarkers to aid early identification of kidney injury. This review considers different methods for measuring kidney function and their contribution to the improvement of detection, monitoring and treatment of chronic kidney disease.

Anti-IFI16 antibodies and their relation to disease characteristics in systemic lupus erythematosus

Objective

Several studies have shown the presence of anti-IFI16 antibodies in systemic lupus erythematosus (SLE), Sjögren Syndrome (SjS), systemic sclerosis (SSc) and other autoimmune diseases. However, the significance of anti-IFI16 antibodies in SLE has not been fully characterized. The aim of this study was to investigate associations between anti-IFI16 antibodies and clinical and serologic parameters of SLE.

Methods

An enzyme-linked immunosorbent assay (ELISA) kit was used to measure anti-IFI16 antibodies in the sera of 168 SLE patients, 46 patients with any type of primary glomerulonephritis (GN) and 182 healthy controls (HCs). Associations between anti-IFI16 antibodies and clinical and serologic parameters of SLE were statistically evaluated using both univariate and multivariate analysis.

Results

Significantly higher anti-IFI16 titres were observed in SLE patients compared to both non-SLE GN and HCs (median levels: 270.1 U/ml vs 132.1 U/ml, p = 0.001, and 52.9 U/ml, p < 0.0001, respectively). With cut-off levels corresponding to the 95th percentile of the control population (113 U/ml), 63% of the SLE patients tested positive for anti-IFI16 autoantibodies, compared to just 24% of patients with primary non-SLE GN and 5% of HCs. The presence of anti-IFI16 antibodies inversely correlated with proteinuria (univariate analysis) and C3 hypocomplementaemia (univariate and multivariate analyses).

Conclusions

The inverse correlations observed between anti-IFI16 positivity, proteinuria and C3 hypocomplementaemia suggest that anti-IFI16 antibodies do not contribute to renal inflammation in SLE; indeed they may even prevent complement consumption. Anti-IFI16 antibodies hold the potential to serve as a new biomarker of disease activity in SLE.

Understanding the mechanisms of proteinuria: therapeutic implications

A large body of evidence indicates that proteinuria is a strong predictor of morbidity, a cause of inflammation, oxidative stress and progression of chronic kidney disease, and development of cardiovascular disease. The processes that lead to proteinuria are complex and involve factors such as glomerular hemodynamic, tubular absorption, and diffusion gradients. Alterations in various different molecular pathways and interactions may lead to the identical clinical end points of proteinuria and chronic kidney disease. Glomerular diseases include a wide range of immune and nonimmune insults that may target and thus damage some components of the glomerular filtration barrier. In many of these conditions, the renal visceral epithelial cell (podocyte) responds to injury along defined pathways, which may explain the resultant clinical and histological changes. The recent discovery of the molecular components of the slit diaphragm, specialized structure of podocyte-podocyte interaction, has been a major breakthrough in understanding the crucial role of the epithelial layer of the glomerular barrier and the pathogenesis of proteinuria. This paper provides an overview and update on the structure and function of the glomerular filtration barrier and the pathogenesis of proteinuria, highlighting the role of the podocyte in this setting. In addition, current antiproteinuric therapeutic approaches are briefly commented.