Estimated Glomerular Filtration Rate in Chronic Kidney Disease: A Critical Review of Estimate-Based Predictions of Individual Outcomes in Kidney Disease

Paper spray mass spectrometry combined with machine learning as a rapid diagnostic for chronic kidney disease

A new analytical method for chronic kidney disease (CKD) detection utilizing paper spray mass spectrometry (PS-MS) combined with machine learning is presented. The analytical protocol is rapid and simple, based on metabolic profile alterations in urine. Anonymized raw urine samples were deposited (10 μL each) onto pointed PS-MS sample strips. Without waiting for the sample to dry, 75 μL of acetonitrile and high voltage were applied to the strips, using high resolution mass spectrometry measurement (15 s per sample) with polarity switching to detect a wide range of metabolites. Random forest machine learning was used to classify the resulting data. The diagnostic performance for the potential diagnosis of CKD was evaluated for accuracy, sensitivity, and specificity, achieving results >96% for the training data and >91% for validation and test data sets. Metabolites selected by the classification model as up- or down-regulated in healthy or CKD samples were tentatively identified and in agreement with previously reported literature. The potential utilization of this approach to discriminate albuminuria categories (normo, micro, and macroalbuminuria) was also demonstrated. This study indicates that PS-MS combined with machine learning has the potential to be used as a rapid and simple diagnostic tool for CKD.

Kidney trajectory charts improve GP management of patients with reduced kidney function: a randomised controlled vignette study

BACKGROUND

The stages of chronic kidney disease (CKD) and estimated glomerular filtration rate (eGFR) reference ranges are currently determined without considering age.

AIM

To determine whether a chart that graphs age with eGFR helps GPs make better decisions about managing patients with declining eGFR.

DESIGN & SETTING

A randomised controlled vignette study among Australian GPs using a percentile chart plotting the trajectory of eGFR by age.

METHOD

Three hundred and seventy-three GPs received two case studies of patients with declining renal function. They were randomised to receive the cases with the chart or without the chart, and asked a series of questions about how they would manage the cases.

RESULTS

In an older female patient with stable but reduced kidney function, use of the chart was associated with GPs in the study recommending a longer follow-up period, and longer time until repeat pathology testing. In a younger male First Nations patient with normal but decreasing kidney function, use of the chart was associated with GPs in the study recommending a shorter follow-up period, shorter time to repeat pathology testing, increased management of blood pressure and lifestyle, and avoidance of nephrotoxic medications. This represents more appropriate care in both cases.

CONCLUSION

Having access to a chart of percentile eGFR by age was associated with more appropriate management review periods of patients with reduced kidney function, either by greater compliance with current guidelines or greater awareness of a clinically relevant kidney problem.

Urinary SPP1 has potential as a non-invasive diagnostic marker for focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a type of chronic glomerular nephropathy showing characteristic glomerular sclerosis, diagnosed by kidney biopsy. However, it is difficult and expensive to monitor disease progression with repeated renal biopsy in clinical practice, and thus here we explored the feasibility of urine biomarkers as non-invasive diagnostic tools. We downloaded scRNA-seq datasets of 20 urine cell samples and 3 kidney tissues and obtained two gene lists encoding extracellular proteins for bioinformatic analysis; in addition, we identified key EP-Genes by immunohistochemical staining and performed bulk RNA sequencing with 12 urine samples. We report that urine cells and kidney cells were correlated. A total of 64 EP-Genes were acquired by intersecting genes of distal tubular cluster with extracellular proteins. Function enrichment analysis showed that EP-Genes might be involved in the immune response and extracellular components. Six key EP-Genes were identified and correlated with renal function. IMC showed that key EP-Genes were located mainly in tubules. Cross verification and examination of a urine RNAseq dataset showed that SPP1 had diagnostic potential for FSGS. The presence of urine SPP1 was primarily associated with macrophage infiltration in kidney, and the pathogenesis of FSGS may be related to innate immunity. Urinary cells seemed to be strongly similar to kidney cells. In summary, SPP1 levels reflect renal function and may have potential as a biomarker for non-invasive diagnosis of FSGS.

Biomarkers of the End-Stage Renal Disease Progression: Beyond the GFR

Chronic kidney disease can progress to the end-stage renal disease (ESRD) characterized by a high risk of morbidity and mortality. ESRD requires immediate therapy or even dialysis or kidney transplantation, therefore, its timely diagnostics is critical for many patients. ESRD is associated with pathological changes, such as inflammation, fibrosis, endocrine disorders, and epigenetic changes in various cells, which could serve as ESRD markers. The review summarizes information on conventional and new ESRD biomarkers that can be assessed in kidney tissue, blood, and urine. Some biomarkers are specific to a particular pathology, while others are more universal. Here, we suggest several universal inflammatory, fibrotic, hormonal, and epigenetic markers indicative of severe deterioration of renal function and ESRD progression for improvement of ESRD diagnostics.

Analysis of the association between glomerular filtration rate, proteinuria and metabolic syndrome in chronic kidney patients based on longitudinal data

Chronic kidney disease (CKD) is a group of chronic diseases caused by kidney damage from multiple causes. Metabolic syndrome (MS) manifests as dysfunction of endothelial cells and chronic functional inflammatory states, and may be involved in pathological changes related to renal impairment. Based on longitudinal data analysis of the association between estimated glomerular filtration rate (eGFR), proteinuria and MS in patients with CKD, this study aims to provide new ideas for the pathophysiological mechanism of CKD and a theoretical basis for the early prevention and effective intervention of MS-related kidney damage. A total of 126 patients with CKD were divided into non-MS group and MS group. According to the eGFR level, 126 patients with CKD were divided into G1 group, G2 group, G3a group, G3b group, G4 group and G5 group. Serum markers such as eGFR, urine protein, and triglycerides (TG) were collected. The correlation between eGFR, urine protein and MS-related indexes was analysed, and the risk factors affecting CKD complicated by MS were analysed. In patients with CKD, the levels of urine protein, abdominal circumference, TG, systolic blood pressure (SBP), diastolic blood pressure (DBP), and fasting blood glucose (FPG) were increased with the course of the disease, but the levels of eGFR and high density lipoprotein (HDL-C) were decreased (p < 0.05). Abdominal circumference, TG, SBP, DBP, FP were significantly negatively correlated with eGFR, but HDL-C was positively correlated with eGFR (p < 0.05). Diabetes, hyperlipidemia, UA, and SBP were independent risk factors affecting CKD complicated MS, and eGFR were independent protective factors (p < 0.05). The combination of diabetes, hyperlipidemia, UA, SBP, and eGFR exhibited higher prediction value for the CKD patients complicated by MS. There was a certain correlation between between MS components with eGFR and urinary protein in patients with CKD. The early intervention treatment of MS was helpful in delaying the development of CKD and reducing proteinuria.

The Impact of Serum Parameters Associated with Kidney Function on the Short-Term Outcomes and Prognosis of Colorectal Cancer Patients Undergoing Radical Surgery

Purpose

The current study was designed to investigate the impact of blood urea nitrogen (BUN), serum uric acid (UA), and cystatin (CysC) on the short-term outcomes and prognosis of colorectal cancer (CRC) patients undergoing radical surgery.

Methods

CRC patients who underwent radical resection were included from Jan 2011 to Jan 2020 in a single clinical centre. The short-term outcomes, overall survival (OS), and disease-free survival (DFS) were compared in different groups. A Cox regression analysis was conducted to identify independent risk factors for OS and DFS.

Results

A total of 2047 CRC patients who underwent radical resection were included in the current study. Patients in the abnormal BUN group had a longer hospital stay (p=0.002) and more overall complications (p=0.001) than that of the normal BUN group. The abnormal CysC group had longer hospital stay (p < 0.01), more overall complications (p=p < 0.01), and more major complications (p=0.001) than the normal CysC group. Abnormal CysC was associated with worse OS and DFS for CRC patients in tumor stage I (p < 0.01). In Cox regression analysis, age (p < 0.01, HR = 1.041, 95% CI = 1.029-1.053), tumor stage (p < 0.01, HR = 2.134, 95% CI = 1.828-2.491), and overall complications (p=0.002, HR = 1.499, 95% CI = 1.166-1.928) were independent risk factors for OS. Similarly, age (p < 0.01, HR = 1.026, 95% CI = 1.016-1.037), tumor stage (p < 0.01, HR = 2.053, 95% CI = 1.788-2.357), and overall complications (p=0.002, HR = 1.440, 95% CI = 1.144-1.814) were independent risk factors for DFS.

Conclusion

In conclusion, abnormal CysC was significantly associated with worse OS and DFS at TNM stage I, and abnormal CysC and BUN were related to more postoperative complications. However, preoperative BUN and UA in the serum might not affect OS and DFS for CRC patients who underwent radical resection.

Postbiotics and Kidney Disease

Chronic kidney disease (CKD) is projected to become the fifth global cause of death by 2040 as a result of key shortcomings in the current methods available to diagnose and treat kidney diseases. In this regard, the novel holobiont concept, used to describe an individual host and its microbial community, may pave the way towards a better understanding of kidney disease pathogenesis and progression. Microbiota-modulating or -derived interventions include probiotics, prebiotics, synbiotics and postbiotics. As of 2019, the concept of postbiotics was updated by the International Scientific Association of Probiotics and Prebiotics (ISAPP) to refer to preparations of inanimate microorganisms and/or their components that confer a health benefit to the host. By explicitly excluding purified metabolites without a cellular biomass, any literature making use of such term is potentially rendered obsolete. We now review the revised concept of postbiotics concerning their potential clinical applications and research in kidney disease, by discussing in detail several formulations that are undergoing preclinical development such as GABA-salt for diet-induced hypertension and kidney injury, sonicated Lactobacillus paracasei in high fat diet-induced kidney injury, GABA-salt, lacto-GABA-salt and postbiotic-GABA-salt in acute kidney injury, and O. formigenes lysates for hyperoxaluria. Furthermore, we provide a roadmap for postbiotics research in kidney disease to expedite clinical translation.