Biomarkers in chronic kidney disease, from kidney function to kidney damage

Machine-learning model based on ultrasomics for non-invasive evaluation of fibrosis in IgA nephropathy

OBJECTIVES

To develop and validate an ultrasomics-based machine-learning (ML) model for non-invasive assessment of interstitial fibrosis and tubular atrophy (IF/TA) in patients with IgA nephropathy (IgAN).

MATERIALS AND METHODS

In this multi-center retrospective study, 471 patients with primary IgA nephropathy from four institutions were included (training, n = 275; internal testing, n = 69; external testing, n = 127; respectively). The least absolute shrinkage and selection operator logistic regression with tenfold cross-validation was used to identify the most relevant features. The ML models were constructed based on ultrasomics. The Shapley Additive Explanation (SHAP) was used to explore the interpretability of the models. Logistic regression analysis was employed to combine ultrasomics, clinical data, and ultrasound imaging characteristics, creating a comprehensive model. A receiver operating characteristic curve, calibration, decision curve, and clinical impact curve were used to evaluate prediction performance.

RESULTS

To differentiate between mild and moderate-to-severe IF/TA, three prediction models were developed: the Rad_SVM_Model, Clinic_LR_Model, and Rad_Clinic_Model. The area under curves of these three models were 0.861, 0.884, and 0.913 in the training cohort, and 0.760, 0.860, and 0.894 in the internal validation cohort, as well as 0.794, 0.865, and 0.904 in the external validation cohort. SHAP identified the contribution of radiomics features. Difference analysis showed that there were significant differences between radiomics features and fibrosis. The comprehensive model was superior to that of individual indicators and performed well.

CONCLUSIONS

We developed and validated a model that combined ultrasomics, clinical data, and clinical ultrasonic characteristics based on ML to assess the extent of fibrosis in IgAN.

KEY POINTS

Question Currently, there is a lack of a comprehensive ultrasomics-based machine-learning model for non-invasive assessment of the extent of Immunoglobulin A nephropathy (IgAN) fibrosis. Findings We have developed and validated a robust and interpretable machine-learning model based on ultrasomics for assessing the degree of fibrosis in IgAN. Clinical relevance The machine-learning model developed in this study has significant interpretable clinical relevance. The ultrasomics-based comprehensive model had the potential for non-invasive assessment of fibrosis in IgAN, which helped evaluate disease progress.

Podocyte-related biomarkers' role in evaluating renal toxic effects of silver nanoparticles with the possible ameliorative role of resveratrol in adult male albino rats

Extensive uses of silver nanoparticles (Ag NPs) in different industries result in exposure to these nanoparticle imperatives in our daily lives. Resveratrol is found in many plants as a natural compound. The present study aimed to estimate the renal toxic effects of Ag NPs in adult male albino rats and the underlying relevant mechanisms while studying the possible role of resveratrol in ameliorating these effects. Thirty adult albino rats were split into 5 groups; control, vehicle, resveratrol (30 mg/kg), Ag NPs (300 mg/kg), and resveratrol + Ag NPs groups. The treatments were given orally for 4 weeks. Ag NPs group displayed a reduction in kidney weight ( absolute and relative), excess in urinary levels of kidney injury molecule, neutrophil gelatinase-associated lipocalin, cystatin, and blood kidney biomarkers (creatinine, urea, and potassium), increases in oxidative stress markers with the reduction in antioxidant markers, and decreases in serum sirtuin 1(SIRT1) level. Upregulation of interleukin 1 beta, tumor necrosis factor-alpha, and monocyte chemoattractant protein-1 gene expressions with downregulation of nephrin and podocin gene expressions in renal tissues were also observed. These changes were associated with histological alterations of the glomeruli and tubules, and increased area percentage of collagen fiber. A significant increase in the optical density of transforming growth factor-beta 1 and claudin-1 immunostaining was detected in the Ag NPs group when compared to other groups. All these changes were alleviated by the usage of resveratrol through its anti-oxidant, anti-inflammatory, and activation of SIRT1 recommending its use as a renoprotective agent.

Establishment of adult reference interval of oxalate in spot urine using real-world data

BACKGROUND

Hyperoxaluria, characterized by excessive oxalate production, can be attributed to high dietary oxalate intake, genetic disorders affecting oxalate metabolism, or certain intestinal diseases. Despite its clinical significance, there is a paucity of comprehensive discussions regarding the reference interval (RI) for oxalate levels in spot urine samples. This study aims to establish an appropriate adult RI for oxalate in spot urine to enhance the interpretation of clinical data.

METHODS

Between January 2021 and July 2021, a cohort of 608 adults aged 19 to 85 years undergoing routine physical examinations was recruited to establish the RI. Additionally, 381 adults with complete datasets were analyzed to examine variables influencing the urinary oxalate/urinary creatinine (UOA/UCr) ratio. Urinary oxalate levels were quantified using a high-performance liquid chromatography assay assured by a proficiency testing from the College of American Pathologists.

RESULTS

The study established sex- and age-specific Ris for the UOA/UCr ratio. For males, three age-specific partitions were identified: 19-29 years (8.499-54.39 mmol/mol), 30-39 years (10.25-61.29 mmol/mol), and ≥ 40 years (12.13-68.69 mmol/mol). In contrast, for females, two age-specific partitions were required: 19-39 years (11.03-64.93 mmol/mol) and ≥ 40 years (11.00-93.84 mmol/mol). UALB/UCr and UREA were recognized as key confounding factors in linear regression that could account for the differences in the UOA/UCr ratio in people.

CONCLUSION

Determining adult RI of oxalate in spot urine is crucial for diagnosing hyperoxaluria. Our sex and age-specific reference intervals will be beneficial for hyperoxaluria screening. The findings regarding the relationship between variables support explaining the variation of UOA/UCr ratio in individuals.

The health-economic impact of urine albumin-to-creatinine ratio testing for chronic kidney disease in Japanese non-diabetic patients

BACKGROUND

The objective of this analysis was to estimate the clinical and economic impact of undertaking urine albumin-to-creatinine ratio (UACR) testing alongside regular estimated glomerular filtration rate testing for chronic kidney disease in non-diabetic Japanese patients versus no testing and versus urine protein-creatinine ratio (UPCR) testing.

METHODS

An economic model, taking a Japanese healthcare perspective, estimated the health-economic impact of UACR testing over a lifetime time horizon. Outcomes reported were additional costs, clinical benefits measured, such as prevented dialyses and cardiovascular events, quality-adjusted life years gained, and incremental cost-effectiveness ratios. Health states were derived from risk levels reported in the Kidney Disease: Improving Global Outcomes heatmap. Results were derived assuming that after testing, treatment was available in the form of current standard-of-care or emerging chronic kidney disease therapies.

RESULTS

Repeated UACR testing was found to be cost-effective compared to both no urine testing and UPCR testing, with incremental cost-effectiveness ratios of ¥1,953,958 and ¥1,966,433, respectively.

CONCLUSION

Overall, this model demonstrates the health-economic value of undertaking UACR testing within the non-diabetic Japanese population.

Economic burden of hospitalization for Chinese children with chronic kidney disease: a comparison between patients with and without infection

Objective

To assess hospitalization costs in pediatric chronic kidney disease (CKD) patients, compare the economic burden between those with and without infections, and identify key factors influencing these costs, emphasizing the significant financial impact on families and healthcare systems.

Methods

This retrospective analysis included pediatric patients with CKD hospitalized between May 2011 and April 2020. Clinical characteristics, including demographics, etiology, urinary protein level, estimated glomerular filtration rate, and CKD stage, were analyzed. Hospitalization costs were compared between groups with and without infection using appropriate statistical methods.

Results

Among 721 pediatric CKD patients included in this study, 388 had primary kidney disease and 333 had secondary kidney disease. Patients in the infection group had significantly higher urine protein levels, longer hospital stays, and higher total hospital fees than those without infection (all P < 0.05). In the primary kidney disease cohort, patients aged 14-18 years incurred the highest costs (16,706 CNY, P = 0.009), while those with 1 + urine protein levels had expenses averaging 29,813 CNY (P = 0.035). In the secondary kidney disease cohort, the 3 + urine protein group had the highest costs (62,841 CNY, P < 0.001). Multiple linear regression identified age, urine protein level, and length of hospital stay as significant cost determinants. Patients with infection in the secondary kidney disease cohort had an average additional expenditure of 13,572.55 CNY compared to those without infection (P = 0.001).

Conclusion

This study highlights the economic burden of infection during pediatric CKD hospitalization, emphasizing the need for effective infection management strategies to reduce financial strain and improve outcomes.

Targeted therapeutic strategy for oral squamous carcinoma using celecoxib-loaded GABA/wheat gluten-alginate nanocarrier hydrogel with glutathione down-regulation and enhanced CCND2-mediated apoptosis

The intricate architecture of the oral cavity results in insufficient surgical excision of oral squamous cell carcinoma (OSCC) potentially increasing the risk of metastasis and recurrence during treatment. In situ generating injectable hydrogels, characterized by minimally invasive methods, encapsulating stability, and pH-responsive breakdown have emerged as viable delivery systems. Herein, we aim to explore a particular therapeutic modality involving the use of celecoxib-loaded GABA/wheat gluten‑sodium alginate (SA/WG-GABA+COX(40)) nanocarriers in enhancing apoptosis of OSCC (HSC-3 & SCC-25). Eventually, drug release profiles show that loaded COX and GABA demonstrated 96.04% and 98.1% at 7.2 pH. Interestingly, crucial experimental techniques like MTT assay, AO/EB staining, DAPI labeling for SCC-25, and HSC-3 displayed the highest cell lysis percentages of 86.5% and 93.3%. Notably, OSCC cell proliferation and migration and cell multiplications were limited with formulated WG/SA-GABA+COX(40) which was evident from In vitro ROS assay, flow cytometry, and JC-1 analysis. In vivo histology, blood serum biochemistry, and tumor examination in xenograft nude mice demonstrated that SA/WG-GABA+COX(40) mice reduced HSC-3 tumor cell proliferation. Downregulation of glutathione and activation of CCND2 signaling pathway caused HSC-3 OSCC cell death. Henceforth, present findings offer an advanced drug delivery method for targeted chemotherapy in treating OSCC.

Association between urinary albumin-to-creatinine ratio within normal range and kidney stones in U.S. adults: a cross-sectional observational study

Background

Kidney stones are a major public health concern, and their prevalence has increased significantly in recent decades. While urinary albumin-to-creatinine ratio (UACR) is a recognized marker for kidney disease, its relationship with kidney stones, especially within the normal UACR range, remains unclear. The purpose of this study was to investigate the association between UACR levels within the normal range and the risk of developing kidney stones.

Methods

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) conducted from 2009 to 2018, focusing on adults aged 20 years and older with available UACR data. Using weighted multivariable logistic regression and restricted cubic spline (RCS) models, we assessed the relationship between UACR levels and the prevalence of kidney stones, adjusting for relevant covariates. Subgroup analyses were also performed to evaluate the consistency of this association across demographic and health-related factors.

Results

The study found that higher UACR levels within the normal range were significantly associated with an increased likelihood of developing kidney stones. Specifically, individuals in the highest quartile of UACR had a 36% higher odds of kidney stones compared to those in the lowest quartile (OR: 1.36, 95% CI: 1.04-1.77). A non-linear, dose-response relationship was observed between UACR levels and kidney stone risk (P < 0.001), with the association remaining consistent across various demographic subgroups.

Conclusion

Elevated UACR levels, even within the normal range, are strongly associated with a higher risk of kidney stones. This finding highlights the potential of UACR as a valuable biomarker for assessing kidney stone risk in clinical practice.

Dual-crosslinked zwitterionic hydrogel: a facile platform of wearable colorimetric urea sensors

Zwitterionic hydrogel based on a dual-crosslinked network of pluronic F-127 dimethacrylate (PLU-DMA) and a terpolymer, poly(sulfobetaine methacrylate)-co-methacrylic acid-co-N-methacryloyloxyethyl tyrosine methylester) (PSBMM) was prepared and successfully applied as an enzyme-based colorimetric sensor of urea on diaper. The prepared hydrogel possessed good mechanical property while preserving its swelling capability. The urease-incorporated hydrogel exhibited a vivid color change from yellow to orange and red, enabling semi-qualitative detection of urea via naked eye in a linear range of 0-0.7 M covering a cut-off value of 0.3 M, which allow for distinguishing between the chronic kidney-prone patients from the normal individuals. The hydrogel was found to be non-toxic and demonstrated effective enzyme preservation by maintaining more than 80% of urease activity up to 14 days. This hydrogel-based urea sensor was also validated by laser desorption ionization mass spectrometry (LDI-MS) with satisfactory results. This platform demonstrated its potential integration on diaper for real-time screening of urea in the point-of-care diagnostics of chronic kidney disease (CKD).

Advancements in Breathomics: Special Focus on Electrochemical Sensing and AI for Chronic Disease Diagnosis and Monitoring

This Review examines the potential of breathomics in enhancing disease monitoring and diagnostic precision when integrated with artificial intelligence (AI) and electrochemical sensing techniques. It discusses breathomics' potential for early and noninvasive disease diagnosis with a focus on chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), and lung cancer, which have been well studied in the context of VOC association with diseases. The noninvasive nature of exhaled breath analysis can be advantageous compared to traditional diagnostic methods for CKD, which often rely on blood and urine testing. VOC analysis can enhance spirometry and imaging methods used in COPD diagnosis, providing a more comprehensive picture of the disease's progression. Breathomics could also provide a less intrusive and potentially earlier diagnostic approach for lung cancer, which is now dependent on imaging and biopsy. The combination of breathomics, electrochemical sensing, and AI could lead to more personalized and successful treatment plans for chronic illnesses using AI algorithms to decipher complicated VOC patterns. This Review assesses the viability and effectiveness of combining breathomics with electrochemical sensors and artificial intelligence by synthesizing recent research findings and technological developments.

The efficacy of novel biomarkers for the early detection and management of acute kidney injury: A systematic review

Acute kidney injury (AKI) is a frequent clinical complication lacking early diagnostic tests and effective treatments. Novel biomarkers have shown promise for enabling earlier detection, risk stratification, and guiding management of AKI. We conducted a systematic review to synthesize evidence on the efficacy of novel biomarkers for AKI detection and management. Database searches yielded 17 relevant studies which were critically appraised. Key themes were biomarker efficacy in predicting AKI risk and severity before functional changes; potential to improve clinical management through earlier diagnosis, prognostic enrichment, and guiding interventions; emerging roles as therapeutic targets and prognostic tools; and ongoing challenges requiring further validation. Overall, novel biomarkers like neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and cell cycle arrest markers ([TIMP-2] •[IGFBP7]) demonstrate capability for very early AKI prediction and accurate risk stratification. Their incorporation has potential to facilitate timely targeted interventions and personalized management. However, factors influencing biomarker performance, optimal cutoffs, cost-effectiveness, and impact on patient outcomes require robust validation across diverse settings before widespread implementation. Addressing these limitations through ongoing research can help translate novel biomarkers into improved detection, prognosis, and management of AKI in clinical practice.

Serum neutrophil gelatinase-associated lipocalin and cystatin C is associated with blood pressure in ex-preterm children and adolescents

BACKGROUND

As preterm birth is a risk factor for hypertension (HTN), biomarkers for early prediction of HTN in childhood is an emerging need. The aims of the study were to evaluate serum biomarkers in ex-preterm children and examine for associations with office peripheral and central SBP (cSBP), ambulatory BP parameters and pulse wave velocity (PWV).

METHODS

This case-control study included children and adolescents born prematurely (ex-preterms) and at full term (controls). All participants underwent office and ambulatory BP monitoring, assessment of cSBP, PWV and serum biomarkers at the same visit. Neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase-2, metalloproteinase-9 (MMP-2, MMP-9) and Cystatin C (CysC) were measured using ELISA.

RESULTS

The study population included 52 ex-preterm individuals and 26 controls. Mean age was 10.7 ± 3.6 years. NGAL, MMP-2, MMP-9, and CysC levels were similar between the ex-preterm and the control group. In the ex-preterm group, NGAL is associated with office SBP z score ( β  = 1.007, 95% CI 1.001-0.014, P  = 0.049), CysC with office DBP z score ( β  = 1.003, 95% CI 1.001-0.005, P  = 0.018) and cSBP z score ( β  = 1.003, 95% CI 1.001-0.005, P  = 0.006) independently of age, sex and BMI z score. Among ex-preterm children and adolescents 17% had ambulatory HTN and 31% had white-coat HTN. NGAL levels were higher in ex-preterm children with WCH compared with children with normal BP [57.9 (IQR 50.8) versus 34.6 (IQR 46.2)], P  = 0.018].

CONCLUSION

WCH is common in ex-preterm children and adolescents and is associated with higher NGAL levels and CysC presents positive association with cSBP. The findings in this study provides preliminary evidence that NGAL and CysC may have a role in predicting the risk of developing hypertension later in life. Further studies are warranted.

Comparison of the prevalence and associated factors of chronic kidney disease diagnosed by serum creatinine or cystatin C among young people living with HIV in Uganda

INTRODUCTION

Young people living with HIV (YPLHIV) are at increased risk of developing chronic kidney disease (CKD) which is associated with high mortality and morbidity. Early diagnosis is important to halt progression. We aimed to estimate the prevalence and factors associated with CKD among YPLHIV in Kampala, Uganda, and to compare serum creatinine and cystatin C for early diagnosis of CKD in this population.

METHODS

A cross-sectional study with YPLHIV aged 10 to 24 years was conducted in seven HIV clinics. Participants provided a urine and blood sample to measure urinary albumin, proteinuria, serum creatinine and cystatin C levels at baseline and after three months. The estimated glomerular filtration rate (eGFR) was calculated using CKDEPI 2021, Cockroft-Gault and bedside Schwartz equations using creatinine or cystatin C. The albumin creatinine ratio (ACR) and proteinuria were measured. CKD was defined as either eGFR < 60 ml/min/1.73m2 or < 90 ml/min/1.73m2 or ACR above 30 mg/g on two separate occasions. Univariable and multivariable logistic regression were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for factors associated with CKD.

RESULTS

A total of 500 participants were enrolled. Most were female (56%; n = 280) and aged 10 to 17 years (66.9%; n = 335). CKD prevalence ranged from 0 to 23% depending on the criteria, equation and biomarker used. Cystatin C-based equations estimated higher prevalence of CKD compared to creatinine-based ones. Prevalence of ACR above 30 mg/g was 10.1% and of proteinuria 29%. Factors independently associated with CKD were age (aOR = 1.42; 95% CI:1.30-1.51) and male sex (aOR = 3.02; 95% CI:1.68-5.43).

CONCLUSION

CKD prevalence among YPLHIV varied substantially depending on definitions used and the current definition would likely lead to missed cases of CKD among YPLHIV. Estimating equations should be validated against measured GFR in YPLHIV and the optimal definition of CKD in this vulnerable population should be revised to optimise detection and opportunities for reducing disease progression.

CLINICAL TRIAL NUMBER

Not applicable.

Toxicity of Oils Extracted From the Arils of Blighia sapida (K.D. Koenig) in Wistar Rats

Blighia sapida oil, a substance with a rich history of use for its nutritional, therapeutic, traditional, and cosmetic benefits, was the focus of our study. We investigated the impact of consuming edible oil from B. sapida arils on Wistar rats. The crude oil from unripe arils was extracted using cold pressing and then administered to the rats. The toxicity was evaluated according to the OECD method. Notably, there were no signs of food poisoning or adverse effects on the weight and behavior of the rats treated with B. sapida oils. The LD50 of the oil was more significant than 5000 mg/kg of body weight, and hematological and biochemical parameters did not differ significantly from the control group. Rats fed with an oil-supplemented diet showed an increase in weight compared to the negative control group. No fatty deposits were found in vital organs, and consuming the oil did not affect the immune system or biochemical biomarkers. However, excessive intake of fat may have harmful effects on tissues. Our findings strongly suggest that B. sapida oil is safe for consumption within reasonable limits. The data we present here reveal that the oil derived from B. sapida is suitable for moderate consumption and may offer various health advantages, a potential that warrants further exploration.

Assessment of Thyroid Function in Chronic Kidney Disease Patients at King Abdulaziz Medical City

Background Chronic kidney disease (CKD) is a progressive and irreversible condition in which the kidneys lose their ability to perform synthetic, excretory, and metabolic functions. CKD is associated with various pathophysiological conditions that impact multiple organs, including the thyroid gland, which primarily secretes triiodothyronine (T3) and thyroxine (T4). This study aims to assess thyroid function in patients with CKD and explore the relationship between renal disease severity and thyroid function. Methods This retrospective study included 200 patients with CKD who were admitted to King Abdulaziz Medical City Hospital, a tertiary center in Jeddah, Saudi Arabia, between 2016 and 2023. Patients were selected based on their age and health status. A predesigned questionnaire was used to collect key demographic, renal, and thyroid function test data, which were then analyzed using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, NY, USA). Results Out of the 200 CKD patients analyzed in this study, 120 (60%) were male and 80 (40%) were female. The results showed that 73.4% (n = 149) had normal thyroid function (euthyroidism). Thirty-nine patients (20.5%) had hypothyroidism, while only two patients (1.1%) had hyperthyroidism. Thyroid-stimulating hormone (TSH), FT3, and FT4 levels were measured across various stages of CKD. Hypothyroidism was most prevalent in stages 5 (30.8%) and 4 (23.1%) based on FT3 levels. It was highest in CKD stage 5 (38.5%) and stage 3 (30.8%) based on T4 levels. Hyperthyroidism was observed in CKD stages 3 (50.0%) and 5 (50.0%) based on TSH levels. Conclusions Patients with CKD exhibit fluctuations in T3 and TSH levels, with thyroid dysfunction increasing in parallel with the severity of renal disease.

Exploring Adiposity and Chronic Kidney Disease: Clinical Implications, Management Strategies, Prognostic Considerations

Obesity poses a significant and growing risk factor for chronic kidney disease (CKD), requiring comprehensive evaluation and management strategies. This review explores the intricate relationship between obesity and CKD, emphasizing the diverse phenotypes of obesity, including sarcopenic obesity and metabolically healthy versus unhealthy obesity, and their differential impact on kidney function. We discuss the epidemiological evidence linking elevated body mass index (BMI) with CKD risk while also addressing the paradoxical survival benefits observed in obese CKD patients. Various measures of obesity, such as BMI, waist circumference, and visceral fat assessment, are evaluated in the context of CKD progression and outcomes. Mechanistic insights into how obesity promotes renal dysfunction through lipid metabolism, inflammation, and altered renal hemodynamics are elucidated, underscoring the role of adipokines and the renin-angiotensin-aldosterone system. Furthermore, the review examines current strategies for assessing kidney function in obese individuals, including the strengths and limitations of filtration markers and predictive equations. The management of obesity and associated comorbidities like arterial hypertension, type 2 diabetes mellitus, and non-alcoholic fatty liver disease in CKD patients is discussed. Finally, gaps in the current literature and future research directions aimed at optimizing the management of obesity-related CKD are highlighted, emphasizing the need for personalized therapeutic approaches to mitigate the growing burden of this intertwined epidemic.

Virus Load Kinetics in Lassa Fever Patients Treated With Ribavirin: A Retrospective Cohort Study From Southern Nigeria

Background

The standard of care for Lassa fever is the use of ribavirin with supportive therapy. There is little information on the course of viremia and its relationship with clinical outcomes in patients treated with ribavirin.

Methods

We conducted a retrospective analysis of virologic and clinical parameters of 152 reverse transcription polymerase chain reaction-confirmed Lassa fever cases admitted and treated with ribavirin therapy. We describe the Lassa virus RNA kinetics in blood in relation to the clinical course of the patients.

Results

The overall mortality was 9%. The median duration (interquartile range [IQR]) of illness before admission was 8 (5-12) days. Median (IQR) Ct values on admission (t0 ) were lower among patients who died (21 [20-27]) than in those who survived (34 [30-37]; P < .01). The receiver operating characteristics curve of the association between outcome and Ct value at t0 had a high classification performance, with an AUC of 0.92 (95% CI, 0.86-0.98). The median time to viral clearance (IQR) was 10 (5-15) days. The viral load decreased steadily with the duration of treatment, and all survivors achieved viral clearance within 25 days of hospitalization.

Conclusions

Our study demonstrates that the Ct value on admission has prognostic value and Lassa fever patients treated with ribavirin typically clear the virus within 3-4 weeks of hospitalization. This kinetics has implications for the design of clinical case management and future clinical trial protocols.

Estimated glomerular filtration rate slope and risk of primary and secondary major adverse cardiovascular events and heart failure hospitalization in people with type 2 diabetes: An analysis of the EXSCEL trial

AIM

The decline in estimated glomerular filtration rate (eGFR), a significant predictor of cardiovascular disease (CVD), occurs heterogeneously in people with diabetes because of various risk factors. We investigated the role of eGFR decline in predicting CVD events in people with type 2 diabetes in both primary and secondary CVD prevention settings.

MATERIALS AND METHODS

Bayesian joint modelling of repeated measures of eGFR and time to CVD event was applied to the Exenatide Study of Cardiovascular Event Lowering (EXSCEL) trial to examine the association between the eGFR slope and the incidence of major adverse CV event/hospitalization for heart failure (MACE/hHF) (non-fatal myocardial infarction, non-fatal stroke, CV death, or hospitalization for heart failure). The analysis was adjusted for age, sex, smoking, systolic blood pressure, baseline eGFR, antihypertensive and lipid-lowering medication, diabetes duration, atrial fibrillation, high-density cholesterol, total cholesterol, HbA1c and treatment allocation (once-weekly exenatide or placebo).

RESULTS

Data from 11 101 trial participants with (n = 7942) and without (n = 3159) previous history of CVD were analysed. The mean ± SD eGFR slope per year in participants without and with previous CVD was -0.68 ± 1.67 and -1.03 ± 2.13 mL/min/1.73 m2, respectively. The 5-year MACE/hHF incidences were 7.5% (95% CI 6.2, 8.8) and 20% (95% CI 19, 22), respectively. The 1-SD decrease in the eGFR slope was associated with increased MACE/hHF risks of 48% (HR 1.48, 95% CI 1.12, 1.98, p = 0.007) and 33% (HR 1.33, 95% CI 1.18,1.51, p < 0.001) in participants without and with previous CVD, respectively.

CONCLUSIONS

eGFR trajectories over time significantly predict incident MACE/hHF events in people with type 2 diabetes with and without existing CVD, with a higher hazard ratio for MACE/hHF in the latter group.

Comparison of the prevalence and associated factors of chronic kidney disease diagnosed by serum creatinine or cystatin C among young people living with HIV in Uganda

Introduction

Young people living with HIV (YPLHIV) are at increased risk of developing chronic kidney disease (CKD) which is associated with high mortality and morbidity. Early diagnosis is important to halt progression. We aimed to estimate the prevalence and factors associated with CKD among YPLHIV in Kampala, Uganda, and to compare serum creatinine and cystatin C for early diagnosis of CKD in this population.

Methods

A cross-sectional study with YPLHIV aged 10 to 24 years was conducted in seven HIV clinics. Participants provided a urine and blood sample to measure urinary albumin, proteinuria, serum creatinine and cystatin C levels at baseline and after three months. The estimated glomerular filtration rate (eGFR) was calculated using CKDEPI 2021, Cockroft-Gault and bedside Schwartz equations using creatinine or cystatin C. The albumin creatinine ratio (ACR) and proteinuria were measured. CKD was defined as either eGFR <60ml/min/1.73m2 or <90ml/min/1.73m2 or ACR above 30mg/g on two separate occasions. Univariable and multivariable logistic regression were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for factors associated with CKD.

Results

A total of 500 participants were enrolled. Most were female (56%; n=280) and aged 10 to 17 years (66.9%; n=335). CKD prevalence ranged from 0-23% depending on the criteria, equation and biomarker used. Cystatin C-based equations estimated higher prevalence of CKD compared to creatinine-based ones. Prevalence of ACR above 30mg/g was 10.1% and of proteinuria 29%. Factors independently associated with CKD were age (aOR=1.42; 95% CI:1.30-1.51) and male sex (aOR=3.02; 95% CI:1.68-5.43).

Conclusion

CKD prevalence among YPLHIV varied substantially depending on definitions used and the current definition would likely lead to missed cases of CKD among YPLHIV. Estimating equations should be validated against measured GFR in YPLHIV and the optimal definition of CKD in this vulnerable population should be revised to optimise detection and opportunities for reducing disease progression.

A Comprehensive Review of Biomarkers for Chronic Kidney Disease in Older Individuals: Current Perspectives and Future Directions

Chronic kidney disease (CKD) is a progressive condition characterized by a gradual loss of kidney function, leading to significant health complications and an increased risk of cardiovascular events. Early detection and effective management are crucial for slowing disease progression and improving patient outcomes. Biomarkers are valuable tools in CKD diagnosis, prognosis, and treatment. Traditional biomarkers, such as serum creatinine and urine protein, are widely used, but emerging biomarkers like cystatin C, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) offer enhanced diagnostic precision and insights into disease severity. These advanced biomarkers are particularly important in older adults, who may present with age-related physiological changes and comorbid conditions that complicate CKD management. This review explores the current state of biomarker research in CKD, focusing on their application in older populations. It highlights the role of traditional and emerging biomarkers, discusses their relevance for early detection and prognosis, and examines future directions in biomarker research, including technological innovations and personalized medicine approaches. By integrating biomarkers into clinical practice, healthcare providers can achieve more accurate diagnoses, tailor treatments to individual patient needs, and potentially improve the overall management of CKD. Continued research and development in this field are essential for addressing the complexities of CKD and advancing patient care.

Is renal dysfunction amplified in an arginine vasopressin induced rat model of preeclampsia?

Renal dysfunction is important in preeclampsia (PE) pathophysiology and has not been fully explored in the arginine vasopressin (AVP) rat model of PE. This study aimed to determine kidney toxicity associated with this model. Female Sprague Dawley rats (n = 24) were subcutaneously infused with AVP or saline for 18 days. Urine samples (GD8, 14 and 18) were used to determine the levels of albumin, VEGF-A, clusterin, NGAL/Lipocalin-2, KIM-1, cystatin C, TIMP-1, β2M and OPN via Multiplex ELISAs. Albumin, and NGAL/lipocalin-2 were significantly elevated in the PAVP vs PS group on GD14 and GD18 (p < 0.001) respectively. VEGF-A significantly decreased in the pregnant vs non-pregnant groups on GD14 and 18 (p < 0.001). Clusterin (p < 0.001) and OPN (p < 0.05) were significantly higher in the PAVP vs PS group on GD18. Cystatin C and KIM-1 are significantly upregulated in the PAVP vs PS groups throughout gestation (p < 0.05). β2M is significantly elevated in the PAVP vs PS group on GD14 and 18 (p < 0.05). AVP elevated the urinary levels of the kidney injury biomarkers and replicated the renal dysfunction associated with PE development. Our findings confirm the potential applications of this model in studying the mechanisms underlying renal damage in PE.

Renal protection after hemorrhagic shock in rats: Possible involvement of SUMOylation

Hemorrhagic shock (HS), a leading cause of preventable death, is characterized by severe blood loss and inadequate tissue perfusion. Reoxygenation of ischemic tissues exacerbates organ damage through ischemia-reperfusion injury. SUMOylation has been shown to protect neurons after stroke and is upregulated in response to cellular stress. However, the role of SUMOylation in organ protection after HS is unknown. This study aimed to investigate SUMOylation-mediated organ protection following HS. Male Wistar rats were subjected to HS (blood pressure of 40 ± 2 mmHg, for 90 min) followed by reperfusion. Blood, kidney, and liver samples were collected at various time points after reperfusion to assess organ damage and investigate the profile of SUMO1 and SUMO2/3 conjugation. In addition, human kidney cells (HK-2), treated with the SUMOylation inhibitor TAK-981 or overexpressing SUMO proteins, were subjected to oxygen and glucose deprivation to investigate the role of SUMOylation in hypoxia/reoxygenation injury. The animals presented progressive multiorgan dysfunction, except for the renal system, which showed improvement over time. Compared to the liver, the kidneys displayed distinct patterns in terms of oxidative stress, apoptosis activation, and tissue damage. The global level of SUMO2/3 in renal tissue was also distinct, suggesting a differential role. Pharmacological inhibition of SUMOylation reduced cell viability after hypoxia-reoxygenation damage, while overexpression of SUMO1 or SUMO2 protected the cells. These findings suggest that SUMOylation might play a critical role in cellular protection during ischemia-reperfusion injury in the kidneys, a role not observed in the liver. This difference potentially explains the renal resilience observed in HS animals when compared to other systems.

Diagnostic performance of an albuminuria point-of-care test in screening for chronic kidney disease among young people living with HIV in Uganda: a cross-sectional study

OBJECTIVES

The main aim was to determine the diagnostic performance of an albuminuria point-of-care test (POC) for diagnosis of chronic kidney disease among young people living with HIV (YPLHIV) in Uganda.

DESIGN

We conducted a cross-sectional study comparing the diagnostic performance of MicroalbuPHAN (Erba Lachema, Czech Republic), an albuminuria POC test against the laboratory-measured albumin and creatinine as the reference standard.

SETTING

The study was set in seven HIV clinics in Kampala, Uganda that provide antiretroviral therapy to adults and children living with HIV. The study took place from April to August 2023.

PARTICIPANTS

497 YPLHIV aged 10-24 years who were diagnosed with HIV before 10 years of age were randomly selected from the HIV clinics. Pregnant YPLHIV were excluded.

PROCEDURES

Participants provided a spot urine sample that was tested for albumin and creatinine using the POC and in the laboratory and proteinuria using urine dipstick. The sensitivity, specificity, negative and positive predictive values (NPV, PPV) of the POC versus the laboratory test were calculated, and factors associated with having a positive POC test were estimated using logistic regression.

OUTCOME MEASURES

The primary outcome was a diagnosis of albuminuria defined as an albumin creatinine ratio above 30 mg/g.

RESULTS

Of the 497 participants enrolled, 278 (55.9%) were female and 331 (66.8%) were aged 10-17 years. The POC test had a sensitivity of 74.5% (95% CI 70.6% to 78.4%) and specificity of 68.1% (95% CI 63.9% to 72.3%). The PPV was 21.5% (95% CI 17.8% to 25.1%) and the NPV was 95.8% (95% CI 94.0% to 97.6%), with an accuracy of 68.8%. There was strong evidence that a positive POC test was associated with having proteinuria (OR 2.82; 95% CI 1.89 to 4.22, p<0.001); body mass index <19.5 (OR 1.69 95% CI 1.17 to 2.45, p=0.005) and being male (OR 1.48; 95% CI 1.02 to 2.14, p=0.04).

CONCLUSIONS

The albuminuria POC test had low sensitivity and specificity. However, it can be used to exclude kidney disease given its high NPV. It should be validated against the 24-hour urinary excretion rate to further determine its diagnostic performance.

Amorphophallus campanulatus tuber extract protects diabetic nephropathy in streptozotocin-induced diabetic nephropathy rat model by regulating oxidative stress and TNF-α inflammatory pathway

PURPOSE

To assess the effect of Amorphophallus campanulatus tuber (Ac) extract in the protection of diabetic nephropathy in streptozotocin (STZ) induced diabetic nephropathy (DN) rat model.

METHODS

Diabetes was induced with STZ (60 mg/kg, i.p.), and DN was confirmed after six weeks of STZ administration with the estimation of kidney function test. Further rats were treated with Ac 250 and 500 mg/kg p.o. for next four week. Oxidative stress and level of inflammatory cytokines were estimated in the kidney tissue of DN rats. Histopathology of kidney tissue was performed using hematoxylin and eosin staining.

RESULTS

There was improvement in the body weight of Ac treated groups than DN group of rats. Blood glucose level was observed to be reduced in Ac treated groups than DN group on 42nd and 70th day of protocol. Treatment with Ac ameliorated the altered level of kidney function tests (creatinine and BUN), enzymes of liver function (aspartate aminotransferase and alanine aminotransferase), and lipid profile in the serum of DN rats. Oxidative stress parameters (malondialdehyde and reactive oxygen species enhances and reduction in the level of glutathione and superoxide dismutase) and inflammatory cytokines such as interleukin-6, tumour necrosis factor-α, and monocyte chemoattractant protein-1 reduces in the tissue of Ac treated group than DN group. Treatment with Ac also attenuates the altered histopathological changes in the kidney tissue of DN rats.

CONCLUSIONS

The report suggests that Ac protects renal injury in DN rats by regulating inflammatory cytokines and oxidative stress.

Perioperative fluid management for adult cardiac surgery: network meta-analysis pooling on twenty randomised controlled trials

BACKGROUND

The aim of this study was to evaluate colloids and crystalloids used in perioperative fluid therapy for cardiac surgery patients to further investigate the optimal management strategies of different solutions.

METHOD

RCTs about adult surgical patients allocated to receive perioperative fluid therapy for electronic databases, including Ovid MEDLINE, EMBase, and Cochrane Central Register of Controlled Trials, were searched up to February 15, 2023.

RESULTS

None of the results based on network comparisons, including mortality, transfuse PLA, postoperative chest tube output over the first 24 h following surgery, and length of hospital stay, were statistically significant. Due to the small number of included studies, the results, including acute kidney injury, serum creatinine, serum microglobulin, and blood urea nitrogen, are from the direct comparison. For transfusion of RBCs, significant differences were observed in the comparisons of 3% gelatine vs. 6% HES 200/0.5, 4% albumin vs. 5% albumin, 4% gelatine vs. 5% albumin, 5% albumin vs. 6% HES 200/0.5, and 6% HES 130/0.4 vs. 6% HES 200/0.5. In transfusion of FFP, significant differences were observed in comparisons of 3% gelatine vs. 4% gelatine, 3% gelatine vs. 6% HES 200/0.5, 5% albumin vs. 6% HES 200/0.5, 4% gelatine vs. 5% albumin, 4% gelatine vs. 6% HES 200/0.4, and 6% HES 130/0.4 vs. 6% HES 200/0.5. For urinary output at 24 h after surgery, the results are deposited in the main text.

CONCLUSION

This study showed that 3% gelatin and 5% albumin can reduce the transfuse RBC and FFP. In addition, the use of hypertonic saline solution can increase urine output, and 5% albumin and 6% HES can shorten the length of ICU stay. However, none of the perioperative fluids showed an objective advantage in various outcomes, including mortality, transfuse PLA, postoperative chest tube output over the first 24 h following surgery, and length of hospital stay. The reliable and sufficient evidences on the injury of the kidney, including acute kidney injury, serum creatinine, serum microglobulin, and blood urea nitrogen, was still lacking. In general, perioperative fluids had advantages and disadvantages, and there were no evidences to support the recommendation of the optimal perioperative fluid for cardiac surgery.

Urine Epidermal Growth Factor and Kidney Function Decline in Middle-Aged Adults

Rationale & Objective

The diagnosis and prognostication of chronic kidney disease (CKD) largely rely on glomerular measures that may not reflect tubular damage. We investigated the associations of urine kidney tubule biomarkers with estimated glomerular filtration rate (eGFR) change among middle-aged adults, when chronic diseases typically emerge.

Study Design

An observational cohort study.

Setting & Participants

A total of 1,145 participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study without CKD, hypertension, or cardiovascular disease at the year 20 visit.

Exposures

Seven different biomarkers of tubular health: urine epidermal growth factor (EGF), alpha-1-microglobulin (α1m), interleukin-18, kidney injury molecule-1, monocyte chemoattractant protein-1, uromodulin, and chitinase-3-like protein 1.

Outcomes

Ten-year eGFR change and incident reduced eGFR (new onset of eGFR < 60 mL/min/1.73 m2).

Analytical Approach

We examined associations of tubular health biomarkers with 10-year eGFR change and incident reduced eGFR with linear mixed models and interval-censored proportional hazards regression models, respectively. Both minimally and fully adjusted models were controlled for urine creatinine levels.

Results

The mean age of participants was 44.8 ± 3.7 years, with 39% African American and 56% female. The average 10-year change in eGFR was -18.6 mL/min/1.73 m2 (95% CI, -19.4 to -17.8). In contrast to the other tubular biomarkers, which showed conflicting results, EGF demonstrated strong, consistent associations with both kidney outcomes. Each 1-standard deviation (SD) higher EGF was associated with a 2.37 mL/min/1.73 m2 (95% CI, 0.64-4.10) smaller 10-year decrease in eGFR and a 42% (95% CI, 4%-64%) lower risk of incident reduced eGFR in the fully adjusted model.

Limitations

Observational design, measurements of eGFR were done only at 5-year intervals during follow-up.

Conclusions

In middle-aged, community-dwelling adults without hypertension, cardiovascular disease or CKD, higher urine EGF concentrations are associated with slower eGFR decline, whereas other kidney tubule biomarkers lacked a consistent association with kidney function decline.

Do the high-protein recommendations for athletes set some on a path to kidney injury and dialysis?

Athletes and fitness enthusiasts are often encouraged to follow high-protein diets to optimize muscle protein synthesis, modify body composition, and enhance performance, yet the safety of these higher protein intakes has been debated. Many people with kidney dysfunction are unaware of their condition, and the potential harm of excess protein intake on the kidneys may not be adequately reported in the sports nutrition literature. Studies suggesting that high-protein intake may be associated with incident kidney disease have led the nephrology community to make conservative recommendations. In contrast, the fitness community suggests that high dietary protein intake is safe and poses no risk of kidney injury. These claims often fail to acknowledge limitations in the internal validity and generalizability of the study results, despite many studies not being adequately powered to support such claims. It is essential to make dietary recommendations that consider the totality of the data and follow the ethical norm of "do no harm." Studies that evaluate the use of high-protein diets among athletes must consider the balance of efficacy with safety. While an intervention may be safe in one population, it does not mean that safety can be assumed for all groups.

The effect of chlorpyrifos oral exposure on the histomorphometric and kidney function in Wistar rat

BACKGROUND

Chlorpyrifos belongs to a broad-spectrum organophosphate insecticide that has high toxicity, is metabolized in the liver by the oxidation reaction, and can inhibit acetylcholinesterase activity. Acetylcholinesterase inhibition generates the reactive oxygen species and induces oxidative stress, which ultimately results in cellular damage like in the kidney. Examining blood urea nitrogen (BUN) levels, creatinine, and kidney histopathology is an appropriate indicator to assess the toxicity of chlorpyrifos to the degree of damage to cells and kidney tissue.

MATERIALS AND METHODS

This research used to determine the effect of duration of exposure to chlorpyrifos and dose-response relationships is important for early detection of the effects of chlorpyrifos toxicity on health. The research study was a true experimental (completely randomized design) consisting of 30 subjects divided into 5 groups. Controlled Group (K1) given 1 mg/kg BW Tween 20 and NaCl 0, 9% until the 56th day. The chlorpyrifos exposed group (P1, P2, P3, and P4) was given chlorpyrifos 5 mg/kg BW for 7, 14, 28, and 56 days. After the treatment, BUN and creatinine levels were measured, and microscopic changes in the kidney were analyzed. The results of BUN, creatinine, and kidney histopathologic were analyzed using the analysis of variance statistical test.

RESULTS

The data result showed that compared to the control group, there were significant increases of BUN and creatinine (P = 0.013 and P = 0.003). Histopathological examinations of kidney glomerulus diameter were also smaller compared to the control group (P = 0.00). All the data measurement indicates significant differences compared to the control group.

CONCLUSIONS

We concluded that sub-chronic oral exposure to chlorpyrifos at low doses can damage the kidneys and cause kidney failure.

Adolescent Kidney Outcomes after Extremely Preterm Birth and Neonatal Acute Kidney Injury: There May be More to the Story

OBJECTIVE

 Among children born extremely preterm (EP), the antecedents of chronic kidney disease (CKD), including neonatal acute kidney injury (nAKI), are not well characterized.

STUDY DESIGN

 This was a retrospective cohort pilot study. Participants (n = 36) were adolescents born before 28 weeks of gestation enrolled at birth into the extremely low gestational age newborn study, between 2002 and 2004, at the University of North Carolina. Participants were stratified by the primary exposure to nAKI, defined using the modified Kidney Disease Improving Global Outcomes nAKI criteria. Baseline serum creatinine (SCr) was defined as the lowest SCr after 48 to 72 postnatal hours. The primary outcome was an abnormal kidney profile during adolescence, defined as having one or more of these outcomes: elevated blood pressure (>120/80 mm Hg), microalbuminuria (urine microalbumin/creatinine >30 µg/g), or an abnormal kidney volume measured by ultrasound (total kidney volume corrected for body surface area <10th%ile for age).

RESULTS

 Half of the participants had a history of nAKI. Thirteen had stage 1 nAKI, four had stage 2, and one had stage 3 nAKI. At 15 years of age, 50% were overweight/obese, 31% had elevated blood pressure (BP), 11% had abnormal kidney volumes, and 17% had microalbuminuria. The relative risk for having an abnormal kidney profile during adolescence among participants with a history of nAKI was 0.63 (95% confidence interval: 0.3-1.3, p = 0.2).

CONCLUSION

 In this sample of adolescents born EP, a history of nAKI was not associated with elevated BP, microalbuminuria, or abnormal kidney volume. Future studies are needed in larger samples to better characterize the relationship between nAKI and CKD in EP-born children.

KEY POINTS

· Extremely preterm birth is associated with acute kidney injury.. · Extremely preterm birth is associated with chronic kidney disease.. · Neonatal acute kidney injury after extremely preterm birth was not associated with kidney outcomes..

Development of a three-dimensional HPLC system for the determination of serine, threonine and allo-threonine enantiomers in the plasma of patients with chronic kidney disease

A highly-selective three-dimensional high-performance liquid chromatographic (3D-HPLC) system was developed for the determination of serine (Ser), threonine (Thr) and allo-threonine (aThr) enantiomers in human plasma to screen the new biomarker of chronic kidney disease (CKD). d-Ser has been reported to be the candidate biomarker of CKD, however, multiple biomarkers are still required. Therefore, Ser analogs of hydroxy amino acids are the focus in the present study. For the sensitive analysis, the amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole and detected by their fluorescence. The 3D-HPLC system consisted of a reversed-phase column (Singularity RP18, 1.0 × 250 mm), an anion-exchange column (Singularity AX, 1.0 × 150 mm) and a Pirkle-type chiral stationary phase (Singularity CSP-013S, 1.5 × 250 mm). The developed method was validated and applied to the human plasma samples obtained from 15 healthy volunteers and 165 CKD patients. The concentrations of the d-forms were 1.13-2.26 (Ser), 0.01-0.03 (Thr) and 0.04-0.10 μM (aThr) for the healthy volunteers and 0.95-19.0 (Ser), 0-0.57 (Thr) and 0.04-1.02 μM (aThr) for the CKD patients. The concentrations and the %d values of all the target d-amino acids were increased along with the decreasing of renal function and further investigation for clinical applications are expected.

Proteomic insights into the pathophysiology of hypertension-associated albuminuria: Pilot study in a South African cohort

BACKGROUND

Hypertension is an important public health priority with a high prevalence in Africa. It is also an independent risk factor for kidney outcomes. We aimed to identify potential proteins and pathways involved in hypertension-associated albuminuria by assessing urinary proteomic profiles in black South African participants with combined hypertension and albuminuria compared to those who have neither condition.

METHODS

The study included 24 South African cases with both hypertension and albuminuria and 49 control participants who had neither condition. Protein was extracted from urine samples and analysed using ultra-high-performance liquid chromatography coupled with mass spectrometry. Data were generated using data-independent acquisition (DIA) and processed using Spectronaut™ 15. Statistical and functional data annotation were performed on Perseus and Cytoscape to identify and annotate differentially abundant proteins. Machine learning was applied to the dataset using the OmicLearn platform.

RESULTS

Overall, a mean of 1,225 and 915 proteins were quantified in the control and case groups, respectively. Three hundred and thirty-two differentially abundant proteins were constructed into a network. Pathways associated with these differentially abundant proteins included the immune system (q-value [false discovery rate] = 1.4 × 10- 45), innate immune system (q = 1.1 × 10- 32), extracellular matrix (ECM) organisation (q = 0.03) and activation of matrix metalloproteinases (q = 0.04). Proteins with high disease scores (76-100% confidence) for both hypertension and chronic kidney disease included angiotensinogen (AGT), albumin (ALB), apolipoprotein L1 (APOL1), and uromodulin (UMOD). A machine learning approach was able to identify a set of 20 proteins, differentiating between cases and controls.

CONCLUSIONS

The urinary proteomic data combined with the machine learning approach was able to classify disease status and identify proteins and pathways associated with hypertension-associated albuminuria.

The use of biological fluids in microfluidic paper-based analytical devices (μPADs): Recent advances, challenges and future perspectives

The use of microfluidic paper-based analytical devices (μPADs) for aiding medical diagnosis is a growing trend in the literature mainly due to their low cost, easy use, simple manufacturing, and great potential for application in low-resource settings. Many important biomarkers (proteins, ions, lipids, hormones, DNA, RNA, drugs, whole cells, and more) and biofluids are available for precise detection and diagnosis. We have reviewed the advances μPADs in medical diagnostics have achieved in the last few years, focusing on the most common human biofluids (whole blood/plasma, sweat, urine, tears, and saliva). The challenges of detecting specific biomarkers in each sample are discussed, along with innovative techniques that overcome such limitations. Finally, the difficulties of commercializing μPADs are considered, and future trends are presented, including wearable devices and integrating multiple steps in a single platform.

Retinoic acid receptor α activity in proximal tubules prevents kidney injury and fibrosis

Chronic kidney disease (CKD) is characterized by a gradual loss of kidney function and affects ~13.4% of the global population. Progressive tubulointerstitial fibrosis, driven in part by proximal tubule (PT) damage, is a hallmark of late stages of CKD and contributes to the development of kidney failure, for which there are limited treatment options. Normal kidney development requires signaling by vitamin A (retinol), which is metabolized to retinoic acid (RA), an endogenous agonist for the RA receptors (RARα, β, γ). RARα levels are decreased in a mouse model of diabetic nephropathy and restored with RA administration; additionally, RA treatment reduced fibrosis. We developed a mouse model in which a spatiotemporal (tamoxifen-inducible) deletion of RARα in kidney PT cells of adult mice causes mitochondrial dysfunction, massive PT injury, and apoptosis without the use of additional nephrotoxic substances. Long-term effects (3 to 4.5 mo) of RARα deletion include increased PT secretion of transforming growth factor β1, inflammation, interstitial fibrosis, and decreased kidney function, all of which are major features of human CKD. Therefore, RARα's actions in PTs are crucial for PT homeostasis, and loss of RARα causes injury and a key CKD phenotype.

Elevated circulating follistatin associates with increased risk of mortality and cardiometabolic disorders

BACKGROUND AND AIMS

Previous study showed that elevated circulating hepatokine follistatin (FST) associates with an increased risk of type 2 diabetes by inducing adipose tissue insulin resistance. Here we explore further the relationships between plasma FST levels with mortality and health outcomes.

METHODS AND RESULTS

The population-based Malmö Diet Cancer cardiovascular cohort (n = 4733, age 45-68 years) was used to study plasma FST in relation to incidence of health outcomes, by linkage with national patient registers. Cox regression analysis was used to assess the associations of plasma FST and outcomes, with adjustments for multiple potential confounding factors. During the mean follow-up time of 22.64 ± 5.84 years in 4,733 individuals, 526 had incident stroke, 432 had ischemic stroke, 530 had incident coronary events (CE), 339 had incident heart failure (HF), 320 had incident chronic kidney disease (CKD) and 1,843 individuals died. Hazard ratio (HR) per standard deviation increase in FST levels adjusted for multiple risk factors was 1.05 (95%CI: 1.00-1.11, p = 0.036) for mortality; 1.10 (95%CI: 1.00-1.20, p = 0.042) for stroke; 1.13 (95%CI: 1.03-1.25, p = 0.014) for ischemic stroke; 1.16 (95%CI: 1.03-1.30, p = 0.015) for HF; and 1.38 (95%CI: 1.12-1.70, p = 0.003) for a diagnosis of CKD. In MDC-CC individuals without prevalent or incident diabetes, the association between FST and stroke, CE and CKD remained significant; but not with mortality or HF.

CONCLUSIONS

Elevated circulating FST associates with an increased risk of mortality and HF, which partly may be mediated by diabetes. FST also associated with stroke, ischemic stroke, CE and CKD, independently of established risk factors including diabetes.

Relationship of Vitamin-D Deficiency with Kidney Disease in Patients with Type-2 Diabetes Mellitus (T2DM) in the Makkah Region: A Cross-Sectional Study

Aim

Vitamin D deficiency is linked with type 2 diabetes mellitus (T2DM) and the occurrence of complications in patients with type 2 diabetes mellitus. None of the studies have focused on the association between vitamin D levels in patients with type 2 diabetes mellitus and diabetic nephropathy (DN) in the Makkah region, Saudi Arabia. Hence, the purpose of this study is to investigate the relationship of vitamin D with kidney disease in patients with T2DM in the Makkah region, of Saudi Arabia.

Materials and Methods

This descriptive cross-sectional study was conducted at different hospitals in the Makkah region on T2DM patients from 2021 to 2022. In total, 328 patients with confirmed diabetes were enrolled in this study. T2DM patients over the aged>18 to 92 years were included in the study. General laboratory characteristics of the study population were measured, including fasting blood sugar, HbA1C (Glycated hemoglobin), vitamin D, kidney function (BUN-Blood urea nitrogen and creatinine), and lipid profiles (cholesterol, triglycerides, LDL-Low density lipoprotein, and HDL-High density lipoprotein).

Results

46.6% (n=153) of participants had normal serum vitamin D levels. Insufficient and deficient serum vitamin D level were observed in 43.9% (n=144) and 9.5% (n=31) of participants, respectively. Of the participants, 25.9% (n=85) had good glycemic control (<7.0%). Moderate and poor glycemic control were observed in 39.9% (n=131) and 34.1% (n=112) of the participants, respectively. A significant negative correlation (p<0.5) was found between vitamin D levels and kidney function test results (blood urea nitrogen and serum creatinine levels). An inverse relationship was observed between HbA1c levels and vitamin D deficiency.

Conclusion

Nephropathy is more likely to develop in people with type 2 diabetes mellitus and vitamin D deficiency.

Repurposing AZD5438 and Dabrafenib for Cisplatin-Induced AKI

SIGNIFICANCE STATEMENT

To combat both untoward effects of nephrotoxicity and ototoxicity in cisplatin-treated patients, two potential therapeutic oral anticancer drugs AZD5438 and dabrafenib, a phase-2 clinical trial protein kinase CDK2 inhibitor and an US Food and Drug Administration-approved drug BRAF inhibitor, respectively, were tested in an established mouse AKI model. Both drugs have previously been shown to protect significantly against cisplatin-induced hearing loss in mice. Each drug ameliorated cisplatin-induced increases in the serum biomarkers BUN, creatinine, and neutrophil gelatinase-associated lipocalin. Drugs also improved renal histopathology and inflammation, mitigated cell death by pyroptosis and necroptosis, and significantly enhanced overall survival of cisplatin-treated mice.

BACKGROUND

Cisplatin is an effective chemotherapy agent for a wide variety of solid tumors, but its use is dose-limited by serious side effects, including AKI and hearing loss. There are no US Food and Drug Administration-approved drugs to treat both side effects. Recently, two anticancer oral drugs, AZD5438 and dabrafenib, were identified as protective against cisplatin-induced hearing loss in mice. We hypothesize that similar cell stress and death pathways are activated in kidney and inner ear cells when exposed to cisplatin and tested whether these drugs alleviate cisplatin-induced AKI.

METHODS

The HK-2 cell line and adult FVB mice were used to measure the protection from cisplatin-induced cell death and AKI by these drugs. Serum markers of kidney injury, BUN, creatinine, and neutrophil gelatinase-associated lipocalin as well as histology of kidneys were analyzed. The levels of markers of kidney cell death, including necroptosis and pyroptosis, pERK, and proliferating cell nuclear antigen, were also examined by Western blotting and immunofluorescence. In addition, CDK2 knockout (KO) mice were used to confirm AZD5438 protective effect is through CDK2 inhibition.

RESULTS

The drugs reduced cisplatin-induced cell death in the HK-2 cell line and attenuated cisplatin-induced AKI in mice. The drugs reduced serum kidney injury markers, inhibited cell death, and reduced the levels of pERK and proliferating cell nuclear antigen, all of which correlated with prolonged animal survival. CDK2 KO mice were resistant to cisplatin-induced AKI, and AZD5438 conferred no additional protection in the KO mice.

CONCLUSIONS

Cisplatin-induced damage to the inner ear and kidneys shares similar cellular beneficial responses to AZD5438 and dabrafenib, highlighting the potential therapeutic use of these agents to treat both cisplatin-mediated kidney damage and hearing loss.

Interpretable machine learning for predicting chronic kidney disease progression risk

Objective

Chronic kidney disease (CKD) poses a major global health burden. Early CKD risk prediction enables timely interventions, but conventional models have limited accuracy. Machine learning (ML) enhances prediction, but interpretability is needed to support clinical usage with both in diagnostic and decision-making.

Methods

A cohort of 491 patients with clinical data was collected for this study. The dataset was randomly split into an 80% training set and a 20% testing set. To achieve the first objective, we developed four ML algorithms (logistic regression, random forests, neural networks, and eXtreme Gradient Boosting (XGBoost)) to classify patients into two classes-those who progressed to CKD stages 3-5 during follow-up (positive class) and those who did not (negative class). For the classification task, the area under the receiver operating characteristic curve (AUC-ROC) was used to evaluate model performance in discriminating between the two classes. For survival analysis, Cox proportional hazards regression (COX) and random survival forests (RSFs) were employed to predict CKD progression, and the concordance index (C-index) and integrated Brier score were used for model evaluation. Furthermore, variable importance, partial dependence plots, and restrict cubic splines were used to interpret the models' results.

Results

XGBOOST demonstrated the best predictive performance for CKD progression in the classification task, with an AUC-ROC of 0.867 (95% confidence interval (CI): 0.728-0.100), outperforming the other ML algorithms. In survival analysis, RSF showed slightly better discrimination and calibration on the test set compared to COX, indicating better generalization to new data. Variable importance analysis identified estimated glomerular filtration rate, age, and creatinine as the most important predictors for CKD survival analysis. Further analysis revealed non-linear associations between age and CKD progression, suggesting higher risks in patients aged 52-55 and 65-66 years. The association between cholesterol levels and CKD progression was also non-linear, with lower risks observed when cholesterol levels were in the range of 5.8-6.4 mmol/L.

Conclusions

Our study demonstrated the effectiveness of interpretable ML models for predicting CKD progression. The comparison between COX and RSF highlighted the advantages of ML in survival analysis, particularly in handling non-linearity and high-dimensional data. By leveraging interpretable ML for unraveling risk factor relationships, contrasting predictive techniques, and exposing non-linear associations, this study significantly advances CKD risk prediction to enable enhanced clinical decision-making.

Exploration of Diagnostic Markers Associated with Inflammation in Chronic Kidney Disease Based on WGCNA and Machine Learning

Chronic kidney disease (CKD) is a common disorder related to inflammatory pathways; its effective management remains limited. This study aimed to use bioinformatics analysis to find diagnostic markers that might be therapeutic targets for CKD. CKD microarray datasets were screened from the GEO database and the differentially expressed genes (DEGs) in CKD dataset GSE98603 were analyzed. Gene set variation analysis (GSVA) was used to explore the activity scores of the inflammatory pathways and samples. Algorithms such as weighted gene co-expression network analysis (WGCNA) and Lasso were used to screen CKD diagnostic markers related to inflammation. Then functional enrichment analysis of inflammation-related DEGs was performed. ROC curves were conducted to examine the diagnostic value of inflammation-related hub-genes. Lastly, quantitative real-time PCR further verified the prediction of bioinformatics. A total of 71 inflammation-related DEGs were obtained, of which 5 were hub genes. Enrichment analysis showed that these genes were significantly enriched in inflammation-related pathways (NF-κB, JAK-STAT, and MAPK signaling pathways). ROC curves showed that the 5 CKD diagnostic markers (TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11) also exhibited good diagnostic value. In addition, TIGD7, ACTA2, ACTG2, and HOXA11 expression was downregulated while MAP4K4 expression was upregulated in LPS-induced HK-2 cells. The present study identified TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11 as reliable CKD diagnostic markers, thereby providing a basis for further understanding of CKD in clinical treatments.

Association between intestinal microflora and renal function in patients with chronic renal failure: A case-control analysis

Objective

To identify the association between the changes in intestinal microflora and renal function in patients with chronic renal failure (CRF).

Methods

This retrospective case-control study included 50 patients with CRF (study group), admitted to the Clinical Laboratory Department of Shenzhen People's Hospital from March 2021 to May 2022, and 50 healthy individuals (control group). The association between the distribution of intestinal microflora and the glomerular filtration rate (GFR), levels of serum creatinine (SCr), blood urea nitrogen (BUN), and serum cystatin C (CysC) were analyzed.

Results

Intestinal microflora of CRF patients had significantly higher levels of Enterococci compared to the control group (p-Value <0.05), while the levels of Bifidobacterium spp. and Escherichia coli were lower in the study group (p-Value <0.05). GFR was lower, and the levels of BUN, SCr, and CysC were higher in the study group compared to the control group (all p-Value <0.05). GFR, BUN, SCr and CysC levels in the study group negatively correlated with the levels of Bifidobacterium spp. and Lactobacillus spp. (r<0, P<0.05), and positively correlated with the abundance of Enterococcus spp. and Escherichia coli (r>0, P<0.05) in the intestinal microflora.

Conclusions

Changes in intestinal microbiota are associated with a significant decrease in GFR and a marked increase in serum levels of renal function indicators, and alterations in the balance of intestinal microbiota may lead to further aggravation of the renal function damage in patients with CRF.

The citrate transporter SLC13A5 as a therapeutic target for kidney disease: evidence from Mendelian randomization to inform drug development

BACKGROUND

Solute carrier family 13 member 5 (SLC13A5) is a Na+-coupled citrate co-transporter that mediates entry of extracellular citrate into the cytosol. SLC13A5 inhibition has been proposed as a target for reducing progression of kidney disease. The aim of this study was to leverage the Mendelian randomization paradigm to gain insight into the effects of SLC13A5 inhibition in humans, towards prioritizing and informing clinical development efforts.

METHODS

The primary Mendelian randomization analyses investigated the effect of SLC13A5 inhibition on measures of kidney function, including creatinine and cystatin C-based measures of estimated glomerular filtration rate (creatinine-eGFR and cystatin C-eGFR), blood urea nitrogen (BUN), urine albumin-creatinine ratio (uACR), and risk of chronic kidney disease and microalbuminuria. Secondary analyses included a paired plasma and urine metabolome-wide association study, investigation of secondary traits related to SLC13A5 biology, a phenome-wide association study (PheWAS), and a proteome-wide association study. All analyses were compared to the effect of genetically predicted plasma citrate levels using variants selected from across the genome, and statistical sensitivity analyses robust to the inclusion of pleiotropic variants were also performed. Data were obtained from large-scale genetic consortia and biobanks, with sample sizes ranging from 5023 to 1,320,016 individuals.

RESULTS

We found evidence of associations between genetically proxied SLC13A5 inhibition and higher creatinine-eGFR (p = 0.002), cystatin C-eGFR (p = 0.005), and lower BUN (p = 3 × 10-4). Statistical sensitivity analyses robust to the inclusion of pleiotropic variants suggested that these effects may be a consequence of higher plasma citrate levels. There was no strong evidence of associations of genetically proxied SLC13A5 inhibition with uACR or risk of CKD or microalbuminuria. Secondary analyses identified evidence of associations with higher plasma calcium levels (p = 6 × 10-13) and lower fasting glucose (p = 0.02). PheWAS did not identify any safety concerns.

CONCLUSIONS

This Mendelian randomization analysis provides human-centric insight to guide clinical development of an SLC13A5 inhibitor. We identify plasma calcium and citrate as biologically plausible biomarkers of target engagement, and plasma citrate as a potential biomarker of mechanism of action. Our human genetic evidence corroborates evidence from various animal models to support effects of SLC13A5 inhibition on improving kidney function.

Involvement of Autophagy and Oxidative Stress-Mediated DNA Hypomethylation in Transgenerational Nephrotoxicity Induced in Rats by the Mycotoxin Fumonisin B1

Fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, is one of the most common pollutants in natural foods and agricultural crops. It can cause chronic and severe health issues in humans and animals. The aim of this study was to evaluate the transgenerational effects of FB1 exposure on the structure and function of the kidneys in offspring. Virgin female Wistar rats were randomly divided into three groups: group one (control) received sterile water, and groups two and three were intragastrically administered low (20 mg/kg) and high (50 mg/kg) doses of FB1, respectively, from day 6 of pregnancy until delivery. Our results showed that exposure to either dose of FB1 caused histopathological changes, such as atrophy, hypercellularity, hemorrhage, calcification, and a decrease in the glomerular diameter, in both the first and second generations. The levels of the antioxidant markers glutathione, glutathione S-transferase, and catalase significantly decreased, while malondialdehyde levels increased. Moreover, autophagy was induced, as immunofluorescence analysis revealed that LC-3 protein expression was significantly increased in both generations after exposure to either dose of FB1. However, a significant decrease in methyltransferase (DNMT3) protein expression was observed in the first generation in both treatment groups (20 mg/kg and 50 mg/kg), indicating a decrease in DNA methylation as a result of early-life exposure to FB1. Interestingly, global hypomethylation was also observed in the second generation in both treatment groups despite the fact that the mothers of these rats were not exposed to FB1. Thus, early-life exposure to FB1 induced nephrotoxicity in offspring of the first and second generations. The mechanisms of action underlying this transgenerational effect may include oxidative stress, autophagy, and DNA hypomethylation.

Effects of kidney perfusion on renal stiffness and tissue fluidity measured with tomoelastography in an MRI-compatible ex vivo model

Stiffness plays a vital role in diagnosing renal fibrosis. However, perfusion influences renal stiffness in various chronic kidney diseases. Therefore, we aimed to characterize the effect of tissue perfusion on renal stiffness and tissue fluidity measured by tomoelastography based on multifrequency magnetic resonance elastography in an ex vivo model. Five porcine kidneys were perfused ex vivo in an MRI-compatible normothermic machine perfusion setup with adjusted blood pressure in the 50/10-160/120 mmHg range. Simultaneously, renal cortical and medullary stiffness and fluidity were obtained by tomoelastography. For the cortex, a statistically significant (p < 0.001) strong positive correlation was observed between both perfusion parameters (blood pressure and resulting flow) and stiffness (r = 0.95, 0.91), as well as fluidity (r = 0.96, 0.92). For the medulla, such significant (p < 0.001) correlations were solely observed between the perfusion parameters and stiffness (r = 0.88, 0.71). Our findings demonstrate a strong perfusion dependency of renal stiffness and fluidity in an ex vivo setup. Moreover, changes in perfusion are rapidly followed by changes in renal mechanical properties-highlighting the sensitivity of tomoelastography to fluid pressure and the potential need for correcting mechanics-derived imaging biomarkers when addressing solid structures in renal tissue.

Machine learning based readmission and mortality prediction in heart failure patients

This study intends to predict in-hospital and 6-month mortality, as well as 30-day and 90-day hospital readmission, using Machine Learning (ML) approach via conventional features. A total of 737 patients remained after applying the exclusion criteria to 1101 heart failure patients. Thirty-four conventional features were collected for each patient. First, the data were divided into train and test cohorts with a 70-30% ratio. Then train data were normalized using the Z-score method, and its mean and standard deviation were applied to the test data. Subsequently, Boruta, RFE, and MRMR feature selection methods were utilized to select more important features in the training set. In the next step, eight ML approaches were used for modeling. Next, hyperparameters were optimized using tenfold cross-validation and grid search in the train dataset. All model development steps (normalization, feature selection, and hyperparameter optimization) were performed on a train set without touching the hold-out test set. Then, bootstrapping was done 1000 times on the hold-out test data. Finally, the obtained results were evaluated using four metrics: area under the ROC curve (AUC), accuracy (ACC), specificity (SPE), and sensitivity (SEN). The RFE-LR (AUC: 0.91, ACC: 0.84, SPE: 0.84, SEN: 0.83) and Boruta-LR (AUC: 0.90, ACC: 0.85, SPE: 0.85, SEN: 0.83) models generated the best results in terms of in-hospital mortality. In terms of 30-day rehospitalization, Boruta-SVM (AUC: 0.73, ACC: 0.81, SPE: 0.85, SEN: 0.50) and MRMR-LR (AUC: 0.71, ACC: 0.68, SPE: 0.69, SEN: 0.63) models performed the best. The best model for 3-month rehospitalization was MRMR-KNN (AUC: 0.60, ACC: 0.63, SPE: 0.66, SEN: 0.53) and regarding 6-month mortality, the MRMR-LR (AUC: 0.61, ACC: 0.63, SPE: 0.44, SEN: 0.66) and MRMR-NB (AUC: 0.59, ACC: 0.61, SPE: 0.48, SEN: 0.63) models outperformed the others. Reliable models were developed in 30-day rehospitalization and in-hospital mortality using conventional features and ML techniques. Such models can effectively personalize treatment, decision-making, and wiser budget allocation. Obtained results in 3-month rehospitalization and 6-month mortality endpoints were not astonishing and further experiments with additional information are needed to fetch promising results in these endpoints.

Effects of Microplastic (MP) Exposure at Environmentally Relevant Doses on the Structure, Function, and Transcriptome of the Kidney in Mice

As a common emerging environmental pollutant, microplastics (MPs) have been detected in a variety of environmental media and human bodies. The potential toxic effects and mechanisms of MPs need to be revealed urgently. MPs can be deposited in the kidney, and exposure to high doses of MPs can cause nephrotoxicity in experimental animals. In this study, we investigated the effects of exposure to polystyrene microplastics (PS-MPs) at environmentally relevant doses (0.1 and 1 mg/L) on kidney structure, function, and transcriptome in mice. We found that mice exposed to PS-MPs in drinking water for eight weeks had no change in body weight or kidney coefficient. PS-MPs administration decreased the levels of blood urea nitrogen (BUN) in mice, while serum creatinine (CRE) and uric acid (UA) concentrations were unaffected. Through using periodic acid-Schiff (PAS) and Masson staining, we discovered that the glomerular tuft area increased in the PS-MP-treated mice, while the degree of renal fibrosis remained unchanged. Furthermore, renal cortex transcriptomic analysis identified 388 and 303 differentially expressed genes (DEGs) in the 0.1 and 1 mg/L dose groups, respectively. The DEGs were highly enriched in mitochondrial-related terms and pathways of thermogenesis and oxidative phosphorylation. Moreover, protein-protein interaction (PPI) network analysis revealed that cytochrome b-c1 complex subunit 10 (UQCR11) and cytochrome c oxidase subunit 3 (MT-CO3) were important node proteins. These findings suggest that environmental exposure to MPs can cause abnormalities in renal structure and filtration function and that long-term exposure to MPs may be a risk factor for renal disease.

The potential of cardiac biomarkers, NT-ProBNP and troponin T, in predicting the progression of nephropathy in diabetic patients: A meta-analysis of prospective cohort studies

AIMS

A meta-analysis was done to investigate the association of two cardiac biomarkers of N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) and circulating troponin T (TnT) with the progression of diabetic nephropathy (DN).

METHODS

A thorough search of the PubMed, Scopus, and Web of Science databases was done until June 2022. The outcome (progression of DN) was described as either of the followings: a) eGFR decline, b) albuminuria, c) end-stage renal disease, or d) mortality. A pooled analysis of eligible studies was performed using random-effect models to compensate for the differences in measurement standards between the studies. We further carried out subgroup analyses to examine our results' robustness and find the source of heterogeneity. A sensitivity analysis was performed to assess the influence of individual studies on the pooled result and the funnel plot and Egger's test were used to assess publication bias.

RESULTS

For NT-proBNP, 8741 participants from 14 prospective cohorts, and for TnT, 7292 participants from 9 prospective cohorts were included in the meta-analysis. Higher NT-proBNP levels in diabetic patients were associated with a higher probability of DN progression (relative risk [RR]: 1.67, 95% confidence interval [CI]: 1.44 to 1.92). Likewise, elevated levels of TnT were associated with an increased likelihood of DN (RR: 1.57, 95% CI: 1.34 to 1.83). The predictive power of both biomarkers for DN remained significant when the subgroup analyses were performed. The risk estimates were sensitive to none of the studies. The funnel plot and Egger's tests indicated publication bias for both biomarkers. Hence, trim and fill analysis was performed to compensate for this putative bias and the results remained significant both for NT-proBNP (RR: 1.50, 95% CI: 1.31 to 1.79) and TnT (RR: 1.35, 95% CI 1.15 to 1.60).

CONCLUSIONS

The increased blood levels of TnT and NT-proBNP can be considered as predictors of DN progression in diabetic individuals. PROSPERO registration code: CRD42022350491.

Urinary Biomarkers of Kidney Tubule Health and Mortality in Persons with CKD and Diabetes Mellitus

Key Points

Among adults with diabetes and CKD, biomarkers of kidney tubule health were associated with a greater risk of death, independent of eGFR, albuminuria, and additional risk factors. Higher urine levels of YKL-40 and KIM-1 were associated with a greater risk of death. For cause-specific death, UMOD was independently and inversely associated with the risk of cardiovascular death.

Background

Kidney disease assessed by serum creatinine and albuminuria are strongly associated with mortality in diabetes. These markers primarily reflect glomerular function and injury. Urine biomarkers of kidney tubule health were recently associated with the risk of kidney failure in persons with CKD and diabetes. Associations of these biomarkers with risk of death are poorly understood.

Methods

In 560 persons with diabetes and eGFR ≤60 ml/min per 1.73 m2 from the Reasons for Geographic and Racial Differences in Stroke study (47% male, 53% Black), we measured urine biomarkers of kidney tubule health at baseline: monocyte chemoattractant protein-1 (MCP-1), alpha-1-microglobulin, kidney injury molecule-1 (KIM-1), EGF, chitinase-3-like protein 1 (YKL-40), and uromodulin (UMOD). Cox proportional hazards regression was used to examine the associations of urine biomarkers with all-cause and cause-specific mortality in nested models adjusted for urine creatinine, demographics, mortality risk factors, eGFR, and urine albumin.

Results

The mean (SD) age was 70 (9.6) years, and baseline eGFR was 40 (3) ml/min per 1.73 m2. There were 310 deaths over a mean follow-up of 6.5 (3.2) years. In fully adjusted models, each two-fold higher urine concentration of KIM-1 and YKL-40 were associated with all-cause mortality (hazard ratio [HR] 1.15, 95% confidence interval [CI], 1.01 to 1.31 and 1.13, 95% CI, 1.07 to 1.20, respectively). When examining cause-specific mortality, higher UMOD was associated with a lower risk of cardiovascular death (adjusted HR per two-fold higher concentration 0.87, 95% CI, 0.77 to 0.99), and higher MCP-1 was associated with higher risk of cancer death (HR per two-fold higher concentration 1.52, 95% CI, 1.05 to 2.18).

Conclusion

Among persons with diabetes and CKD, higher urine KIM-1 and YKL-40 were associated with a higher risk of all-cause mortality independently of established risk factors. Urine UMOD and MCP-1 were associated with cardiovascular and cancer-related death, respectively.

Risk factor mining and prediction of urine protein progression in chronic kidney disease: a machine learning- based study

BACKGROUND

Chronic kidney disease (CKD) is a global public health concern. Therefore, to provide timely intervention for non-hospitalized high-risk patients and rationally allocate limited clinical resources is important to mine the key factors when designing a CKD prediction model.

METHODS

This study included data from 1,358 patients with CKD pathologically confirmed during the period from December 2017 to September 2020 at Zhongshan Hospital. A CKD prediction interpretation framework based on machine learning was proposed. From among 100 variables, 17 were selected for the model construction through a recursive feature elimination with logistic regression feature screening. Several machine learning classifiers, including extreme gradient boosting, gaussian-based naive bayes, a neural network, ridge regression, and linear model logistic regression (LR), were trained, and an ensemble model was developed to predict 24-hour urine protein. The detailed relationship between the risk of CKD progression and these predictors was determined using a global interpretation. A patient-specific analysis was conducted using a local interpretation.

RESULTS

The results showed that LR achieved the best performance, with an area under the curve (AUC) of 0.850 in a single machine learning model. The ensemble model constructed using the voting integration method further improved the AUC to 0.856. The major predictors of moderate-to-severe severity included lower levels of 25-OH-vitamin, albumin, transferrin in males, and higher levels of cystatin C.

CONCLUSIONS

Compared with the clinical single kidney function evaluation indicators (eGFR, Scr), the machine learning model proposed in this study improved the prediction accuracy of CKD progression by 17.6% and 24.6%, respectively, and the AUC was improved by 0.250 and 0.236, respectively. Our framework can achieve a good predictive interpretation and provide effective clinical decision support.

Urinary growth differentiation factor 15 predicts renal function decline in diabetic kidney disease

Sensitive biomarkers can enhance the diagnosis, prognosis, and surveillance of chronic kidney disease (CKD), such as diabetic kidney disease (DKD). Plasma growth differentiation factor 15 (GDF15) levels are a novel biomarker for mitochondria-associated diseases; however, it may not be a useful indicator for CKD as its levels increase with declining renal function. This study explores urinary GDF15's potential as a marker for CKD. The plasma and urinary GDF15 as well as 15 uremic toxins were measured in 103 patients with CKD. The relationship between the urinary GDF15-creatinine ratio and the uremic toxins and other clinical characteristics was investigated. Urinary GDF15-creatinine ratios were less related to renal function and uremic toxin levels compared to plasma GDF15. Additionally, the ratios were significantly higher in patients with CKD patients with diabetes (p = 0.0012) and reduced with statin treatment. In a different retrospective DKD cohort study (U-CARE, n = 342), multiple and logistic regression analyses revealed that the baseline urinary GDF15-creatinine ratios predicted a decline in estimated glomerular filtration rate (eGFR) over 2 years. Compared to the plasma GDF15 level, the urinary GDF15-creatinine ratio is less dependent on renal function and sensitively fluctuates with diabetes and statin treatment. It may serve as a good prognostic marker for renal function decline in patients with DKD similar to the urine albumin-creatinine ratio.

Non-invasive chronic kidney disease risk stratification tool derived from retina-based deep learning and clinical factors

Despite the importance of preventing chronic kidney disease (CKD), predicting high-risk patients who require active intervention is challenging, especially in people with preserved kidney function. In this study, a predictive risk score for CKD (Reti-CKD score) was derived from a deep learning algorithm using retinal photographs. The performance of the Reti-CKD score was verified using two longitudinal cohorts of the UK Biobank and Korean Diabetic Cohort. Validation was done in people with preserved kidney function, excluding individuals with eGFR <90 mL/min/1.73 m² or proteinuria at baseline. In the UK Biobank, 720/30,477 (2.4%) participants had CKD events during the 10.8-year follow-up period. In the Korean Diabetic Cohort, 206/5014 (4.1%) had CKD events during the 6.1-year follow-up period. When the validation cohorts were divided into quartiles of Reti-CKD score, the hazard ratios for CKD development were 3.68 (95% Confidence Interval [CI], 2.88-4.41) in the UK Biobank and 9.36 (5.26-16.67) in the Korean Diabetic Cohort in the highest quartile compared to the lowest. The Reti-CKD score, compared to eGFR based methods, showed a superior concordance index for predicting CKD incidence, with a delta of 0.020 (95% CI, 0.011-0.029) in the UK Biobank and 0.024 (95% CI, 0.002-0.046) in the Korean Diabetic Cohort. In people with preserved kidney function, the Reti-CKD score effectively stratifies future CKD risk with greater performance than conventional eGFR-based methods.

Early renal impairment affects hormonal regulators of calcium and bone metabolism and Wnt signalling and the response to vitamin D supplementation in healthy older adults

Bone and renal metabolism are regulated by common factors and there is extensive cross-talk between these organs (the 'renal-bone-axis'). Ageing is associated with physiological changes including reduced bone mass, renal function and tissue sensitivity to regulatory hormones, impacting the renal-bone axis. We aimed to investigate the influence of estimated Glomerular Filtration Rate (eGFR) on plasma concentrations of vitamin D metabolites, Wnt signalling and bone metabolism in a dose ranging vitamin D₃ RCT (12,000 IU, 24,000 IU, 48,000 IU/month for 1 year; n = 379, >70 y) with a baseline eGFR > 30 mL/min/1.73 m². Participants were categorised on basis of eGFR (≥60 or mL/min/1.73 m²) based on 5 commonly used algorithms for eGFR. Differences between eGFR categories were tested with ANCOVA. Before supplementation commenced, a lower eGFR was associated with significantly higher concentrations of c-terminal and intact Fibroblast Growth Factor-23 (cFGF23; iFGF23), intact Parathyroid Hormone (iPTH) and Sclerostin (SOST) and lower Klotho, 1,25-dihydroxy Vitamin D (1,25(OH)₂D) and Dickkopf-related Protein 1 (DKK1) concentrations. Differences between eGFR groups in 25-hydroxy Vitamin D (25(OH)D), 24,25-dihydroxy Vitamin D (24,25(OH)₂D) and iPTH were only detected with eGFR based on Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification in Diet for Renal Disease (MDRD-4) algorithms. Differences in Bone Mineral Density and Content (BMD; BMC) and bone turnover markers were detected only with Cockcroft-Gault (CG). Pre- and post- supplementation comparisons showed differences in the response to supplementation by eGFR group. Plasma 25(OH)D, 24,25(OH)₂D, 1,25(OH)₂D and DKK1 increased and iPTH and C-terminal telopeptide (CTX) decreased in both groups. Plasma iFGF23, bone specific alkaline phosphatase (BAP) and Procollagen 1 intact N-terminal Propeptide (PINP) increased and phosphate decreased only in the group with eGFR ≥ 60 mL/min/1.73 m². Findings were largely consistent across all eGFR algorithms. Post-supplementation, cFGF23, iFGF23, iPTH and SOST remained significantly higher in the lower eGFR group. Plasma 1,25(OH)₂D and Klotho did no longer differ between eGFR groups. This was found for all eGFR algorithms, with the exception of iPTH and iFGF23, which were not significantly different with eGFR based on CG. Differences in BMD and BMC were detected with CKD-EPI-creatinine and MDRD-4 but not GC. This study showed that even a moderate decline in eGFR is associated with alterations in vitamin D metabolism, Wnt signalling and bone turnover markers. Renal function influenced the response to vitamin D supplementation. Supplementation increased Vitamin D metabolites in the group with moderate renal impairment to concentrations comparable to those found in the group with normal renal function. However, although CTX decreased, an increase in bone formation markers was not found in the group with eGFR 60 mL/min/1.73 m². In conclusion, vitamin D supplementation had beneficial effects on markers of the renal-bone axis in older people with both normal and impaired renal function.