The effect of glucocorticoids on serum cystatin C in identifying acute kidney injury: a propensity-matched cohort study

Shrunken pore syndrome in heart transplantation: a pore ready to close?

Background: A newly discovered renal syndrome, shrunken pore syndrome (SPS), has been shown to increase mortality regardless of renal function. SPS is defined as an estimated glomerular filtration rate (eGFR) of cystatin C ≤ 60% than eGFRcreatinine. We set out to study SPS in relation to the survival of heart transplantation patients with a follow-up of up to 12 years. Methods. This was a single-center cohort study including 253 consecutive patients undergoing heart transplantation. The prevalence of SPS at different time points post-transplantation and its effect on survival was evaluated using Kaplan-Meier's analysis and multivariable Cox proportional hazards regression. Results. The prevalence of SPS was 7.5% the day after transplantation (D1), which rose to 71% week 4 after surgery. There was no difference in survival for patients with SPS D1 compared to patients without SPS D1. Patients with SPS 4 weeks compared to patients without SPS 4 weeks after transplantation showed a 5- and 10-year survival of 73% vs. 93% (p = .02) and 63% vs. 90% (p = .005), respectively. SPS developed during the postoperative period was also found to be an independent predictor of mortality (HR 4.65; 95% CI 1.36-15.8). Discussion. SPS that developed in the postoperative course after heart transplantation was found to be an independent predictor of mortality with a severe negative impact on 5- and 10-year survival.

Implementation and One-Year Evaluation of Proenkephalin A in Critical Care

Proenkephalin A 119-159 (PENK) is a promising functional kidney biomarker, evaluated in various clinical settings. In critical care medicine, early diagnosis of acute kidney injury (AKI) is crucial; however, to date, the diagnosis and the assessment of kidney function is still based on serum creatinine (sCr) and urine output, both associated with several limitations. Between November 2020 and March 2022, we implemented PENK in our daily practice on our intensive care units (ICU). PENK, sCr, AKI stage, and the start and duration of renal replacement therapy (RRT) were documented. Almost 18,000 PENK measurements from 4169 patients were analyzed, and the glomerular filtration rate (GFR) was estimated with the new PENK-GFR formula. PENK outperformed sCR in the kidney function assessment and sCR trajectory over time. Moreover, PENK predicted the use of RRT and thus showed its usefulness in critical care daily practice.

The protective effect of Argan oil and its main constituents against xenobiotics-induced toxicities

BACKGROUND

Argan oil (AO) is a vegetable oil extracted from the fruits of Argania spinosa L. tree, belonging to the Sapotaceae family, primarily found in Morocco. Research studies have demonstrated that AO exhibits diverse pharmacological properties, including antioxidant, antimicrobial, anticancer, antiinflammatory, antidiabetic, antihypercholesterolemic, antiatherogenic, and immunomodulatory effects. These effects are attributed to its main constituents, including oleic acid, linoleic acid, γ-tocopherol, α-tocopherol, and ferulic acid.

OBJECTIVE

This review aimed to present the protective role of AO and its main constituents against xenobiotics-induced toxicities.

MATERIAL AND METHODS

Based on results from various in vitro and in vivo investigations published in the main scientific databases, the beneficial action of AO against xenobiotics-induced toxicities was analyzed.

RESULTS

AO and its main constituents have reduced neurotoxicity, hepatotoxicity, nephrotoxicity, pneumotoxicity, thyroid toxicity, hematotoxicity, immunotoxicity, genotoxicity, and colon toxicity induced by different natural and chemical xenobiotics. Different mechanisms of action are involved in these effects, including enhancement of antioxidant defense, reduction of oxidative stress, modulation of inflammation, stimulation of fatty acid oxidation, suppression of apoptosis, regulation of miRNAs expression, elevation of acetylcholinesterase activity, activation of Krebs cycle enzymes, and restoration of mitochondrial function.

CONCLUSION

The study shows clearly the beneficial effect of Argan oil against xenobiotics-induced toxicities was analyzed. However, clinical trials are necessary to verify the protective effects of this oil in human intoxications caused by both natural and chemical xenobiotics.

The nadir platelet count in the first 48 h after ICU admission is a potential predictor of acute kidney injury in hemorrhagic shock patients

BACKGROUND

The relationship between the nadir platelet count within the first 48 h after intensive care unit (ICU) admission and the occurrence of acute kidney injury (AKI) in hemorrhagic shock patients remains unclear. This study investigated this association in adult patients admitted to the surgical ICU for hemorrhagic shock.

METHODS

We included 124 hemorrhagic shock patients, excluding those with pre-existing AKI or chronic kidney disease (CKD), admitted to two affiliated hospitals between January 2019 and May 2022. The nadir platelet count was defined as the lowest value within the first 48 h after ICU admission. AKI was diagnosed based on Kidney Disease Improving Global Outcomes (KDIGO) criteria. We used multivariate logistic regression to identify independent risk factors for AKI and analyzed the area under the receiver operating characteristic curve (AUC) for diagnostic accuracy.

RESULTS

Patients with AKI (n = 72) had significantly lower nadir platelet counts compared to those without AKI. The nadir platelet count was identified as an independent risk factor for AKI (OR = 0.988, 95% CI: 0.978-0.999, P = 0.035). The AUC for predicting AKI was 0.862 (95% CI: 0.795-0.929). Combining the nadir platelet count with serum cystatin C levels enhanced the predictive accuracy (AUC = 0.922, 95% CI: 0.870-0.973, P < 0.001).

CONCLUSIONS

The nadir platelet count in the first 48 h after ICU admission is independently associated with the risk of AKI in hemorrhagic shock patients and could serve as a potential predictor when combined with serum cystatin C levels.

Cystatin C and Kidney Function Recovery in Patients Requiring Continuous KRT for Acute Kidney Injury

Key Points

Plasma cystatin C is decreased in participants with AKI requiring continuous KRT (CKRT) with early kidney function recovery. Despite being cleared by CKRT, plasma cystatin C in the first 3 days of CKRT may be a useful clinical tool to help predict the prognosis of AKI requiring CKRT.

Background

Plasma cystatin C is a reliable marker to estimate kidney function; however, it is unknown whether this remains true in patients receiving continuous KRT (CKRT). In this study, we tested the hypothesis that lower concentrations of plasma cystatin C during the first 3 days of CKRT would predict kidney function recovery.

Methods

We performed a retrospective observational study of 72 patients from a 126-patient, single-center CKRT study. We studied two a priori defined cohorts of patients without advanced CKD who had AKI requiring CKRT: (1 ) with early kidney function recovery defined as liberation from KRT within 7 days of CKRT initiation versus (2 ) with delayed kidney function recovery defined as receipt of KRT for >21 days or death while on KRT. Subsequent analysis included patients with advanced CKD and intermediate kidney function recovery (liberation between 8 and 21 days). Cystatin C was then measured on stored plasma, urine, and dialysis effluent collected before CKRT initiation and on days 1, 2, and 3 of CKRT.

Results

Plasma cystatin C was significantly lower in patients with early kidney function recovery in comparison with patients with delayed kidney function recovery on days 1 (1.79 versus 2.39 mg/L), 2 (1.91 versus 2.38 mg/L), and 3 (2.04 versus 2.67 mg/L) of CKRT. Sieving coefficient and CKRT clearance of cystatin C were similar for patients with early and delayed kidney function recovery. The lowest plasma cystatin C concentration on days 1–3 of CKRT predicted early kidney function recovery with an area under the receiver operating curve of 0.77 (P =0.002), positive likelihood ratio of 5.60 for plasma cystatin C <1.30 mg/L, and negative likelihood ratio of 0.17 for plasma cystatin C ≥1.88 mg/L.

Conclusions

Lower plasma cystatin C concentrations during the first 3 days of CKRT are associated with early kidney function recovery.

Predictive performance of glomerular filtration rate equations based on cystatin C, creatinine and their combination in critically ill patients

OBJECTIVE

24-hour urine creatinine clearance (ClCr 24 hours) remains the gold standard for estimating glomerular filtration rate (GFR) in critically ill patients; however, simpler methods are commonly used in clinical practice. Serum creatinine (SCr) is the most frequently used biomarker to estimate GFR; and cystatin C, another biomarker, has been shown to reflect GFR changes earlier than SCr. We assess the performance of equations based on SCr, cystatin C and their combination (SCr-Cyst C) for estimating GFR in critically ill patients.

METHODS

Observational unicentric study in a tertiary care hospital. Patients with cystatin C, SCr and ClCr 24 hours measurements in ±2 days admitted to an intensive care unit were included. ClCr 24 hours was considered the reference method. GFR was estimated using SCr-based equations: Chronic Kidney Disease Epidemiology Collaboration based on creatinine (CKD-EPI-Cr) and Cockcroft-Gault (CG); cystatin C-based equations: CKD-EPI-CystC and CAPA; and Cr-CystC-based equations: CKD-EPI-Cr-CystC. Performance of each equation was assessed by calculating bias and precision, and Bland-Altman plots were built. Further analysis was performed with stratified data into CrCl 24 hours <60, 60-130 and ≥130 mL/min/1.73 m2.

RESULTS

We included 275 measurements, corresponding to 186 patients. In the overall population, the CKD-EPI-Cr equation showed the lowest bias (2.6) and best precision (33.1). In patients with CrCl 24 hours <60 mL/min/1.73 m2, cystatin-C-based equations showed the lowest bias (<3.0) and CKD-EPI-Cr-CystC was the most accurate (13.6). In the subgroup of 60≤ CrCl 24 hours <130mL/min/1.73 m2, CKD-EPI-Cr-CystC was the most precise (20.9). However, in patients with CrCl 24 hours ≥130mL/min/1.73 m2, cystatin C-based equations underestimated GFR, while CG overestimated it (22.7).

CONCLUSIONS

Our study showed no evidence of superiority of any equation over the others for all evaluated parameters: bias, precision and Lin's concordance correlation coefficient. Cystatin C-based equations were less biased in individuals with impaired renal function (GFR <60 mL/min/1.73 m2). CKD-EPI-Cr-CystC performed properly in patients with GFR from 60-130 mL/min/1.73 m2 and none of them were accurate enough in patients ≥130 mL/min/1.73 m2.

Determination of cystatin C reference interval for children in Croatia

Introduction

Cystatin C is considered an early marker of kidney damage. The aim was to determine the reference interval in children since this information was not available from the test manufacturer.

Materials and methods

Included were children aged 0 to 18 years undergoing routine check without history of any renal disease. Cystatin C was measured by the immunoturbidimetric method, and creatinine by the enzymatic method on a Cobas c501 analyzer (Roche Diagnostics, Manheim, Germany). Reference intervals were determined according to the CLSI C28-A3 guidelines using a robust method and a nonparametric percentile method, depending on the sample size. The Schwartz's formula was applied to estimate glomerular filtration (eGFR) from cystatin C.

Results

The cystatin C reference interval for children aged 1-18 years (N = 204, median 8 years) was from 0.61 mg/L (90% CI: 0.53 to 0.64) to 1.08 mg/L (90% CI: 1.07 to 1.14). Differences according to sex were not found. For children aged 0-1 years (N = 29, median 5 months), the reference interval was from 0.60 mg/L (90% CI: 0.48 to 0.72) to 1.49 mg/L (90% CI: 1.36 to 1.61). The sample size was too small to test the difference according to sex. The eGFR was 76 (70-88) mL/min/1.73m2 for males and 83 (74-92) mL/min/1.73m2 for females.

Conclusion

The cystatin C reference intervals for Croatian pediatric population according to age were determined. The cystatin C concentrations in children reach adulthood values after the first year. The cystatin C Schwartz's formula is applicable for eGFR calculation in children.

Rapid development of cefiderocol resistance in a carbapenem-resistant Pseudomonas aeruginosa isolate associated with mutations in the pyoverdine biosynthesis pathway

Here we report the in vivo development of cefiderocol resistance within 11 days after therapy initiation in a critically ill patient with bloodstream infection, infection of peri-anal fistula, and pneumonia caused by a VIM-2 harbouring, carbapenem-resistant Pseudomonas aeruginosa. Compared to a cefiderocol-naïve P. aeruginosa blood culture isolate, agar diffusion susceptibility testing found a reduced cefiderocol inhibition zone diameter in a P. aeruginosa recovered from peri-anal abscess tissue cultures after initiation of cefiderocol therapy. Subsequent whole-genome sequencing suggested that both isolates were of clonal origin. Comparison of genomes found an accumulation of missense mutations within pvdP, pvdE, pvdJ, and pvdD (i.e. genes associated with biosynthesis of pyoverdine), the main siderophore produced by P. aeruginosa. Quantification of pyoverdine production under iron-depleted conditions showed a significantly (P = 0.0003) higher pyoverdine production by the cefiderocol-resistant isolate. While pyoverdine quantity alone appears not to be decisive for cefiderocol resistance, the reported case highlights the potentially rapid emergence of cefiderocol resistance in P. aeruginosa and points towards a potential involvement of iron up-take systems in this process.

Serum N-terminal pro-B-type natriuretic peptide and cystatin C for acute kidney injury detection in critically ill adults in China: a prospective, observational study

OBJECTIVE

Serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cystatin C (sCysC) are available clinically and beneficial in diagnosing acute kidney injury (AKI). Our purpose is to identify the performance of their combined diagnosis for AKI in critically ill patients.

DESIGN

A prospectively recruited, observational study was performed.

SETTING

Adults admitted to the intensive care unit of a tertiary hospital in China.

PARTICIPANTS

A total of 1222 critically ill patients were enrolled in the study.

MAIN OUTCOME MEASURES

To identify the performance of the combined diagnosis of serum NT-proBNP and sCysC for AKI in critically ill patients. The area under the receiver operating characteristic curve (AUC-ROC), category-free net reclassification index (NRI) and incremental discrimination improvement (IDI) were utilised for comparing the discriminative powers of a combined and single biomarker adjusted model of clinical variables enriched with NT-proBNP and sCysC for AKI.

RESULTS

AKI was detected in 256 out of 1222 included patients (20.9%). AUC-ROC for NT-proBNP and sCysC to detect AKI had a significantly higher accuracy than any individual biomarker (p<0.05). After multivariate adjustment, a level of serum NT-proBNP ≥204 pg/mL was associated with 3.5-fold higher odds for AKI compared with those below the cut-off value. Similar results were obtained for sCysC levels (p<0.001). To detect AKI, adding NT-proBNP and sCysC to a clinical model further increased the AUC-ROC to 0.859 beyond that of the clinical model with or without sCysC (p<0.05). Moreover, the addition of these two to the clinical model significantly improved risk reclassification of AKI beyond that of the clinical model alone or with single biomarker (p<0.05), as measured by NRI and IDI.

CONCLUSIONS

In critically ill individuals, serum NT-proBNP, sCysC and clinical risk factors combination improve the discriminative power for diagnosing AKI.

Prediction of acute kidney injury after total aortic arch replacement with serum cystatin C and urine N-acetyl-β-d-glucosaminidase: A prospective observational study

BACKGROUND

Acute kidney injury (AKI) after total aortic arch replacement (TAAR) is frequent and associated with adverse outcomes, whereas its early detection remains a challenge. Serum cystatin C (sCysC) and urinary N-acetyl-β-d-glucosaminidase (uNAG) are clinically available renal biomarkers, but their combination for AKI detection requires more evidence. This study aimed to assess the discriminative abilities of these biomarkers in AKI after TAAR.

MATERIALS AND METHODS

Patients undergoing TAAR were included in this prospective observational study. The AKI prediction model was developed and internal verificated, and the significance of each variable was analyzed by random forest (RF). Finally, the best predictive critical values of sCysC and uNAG were explored by the AUC-ROC curve.

RESULTS

The AUC-ROC of the prediction model was substantially enhanced by adding sCysC and uNAG (0.909 vs 0.844, p < 0.001), and the clinical utility and risk reclassification were significantly improved. Additionally, the RF showed that sCysC and uNAG ranked first and second. The AUC-ROC for each were 0.864 and 0.802 respectively, and the cut-off values were 1.395 mg/L and 31.90 U/g Cre respectively.

CONCLUSION

The prediction model incorporating functional marker sCysC and tubular injury marker uNAG can improve the discriminative abilities of AKI after TAAR.

Urinary proteome analysis of acute kidney injury in post-cardiac surgery patients using enrichment materials with high-resolution mass spectrometry

Background: Cardiac surgery-associated acute kidney injury (CSA-AKI) may increase the mortality and incidence rates of chronic kidney disease in critically ill patients. This study aimed to investigate the underlying correlations between urinary proteomic changes and CSA-AKI.

Methods: Nontargeted proteomics was performed using nano liquid chromatography coupled with Orbitrap Exploris mass spectrometry (MS) on urinary samples preoperatively and postoperatively collected from patients with CSA-AKI. Gemini C18 silica microspheres were used to separate and enrich trypsin-hydrolysed peptides under basic mobile phase conditions. Differential analysis was conducted to screen out urinary differential expressed proteins (DEPs) among patients with CSA-AKI for bioinformatics. Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis was adopted to identify the altered signal pathways associated with CSA-AKI.

Results: Approximately 2000 urinary proteins were identified and quantified through data-independent acquisition MS, and 324 DEPs associated with AKI were screened by univariate statistics. According to KEGG enrichment analysis, the signal pathway of protein processing in the endoplasmic reticulum was enriched as the most up-regulated DEPs, and cell adhesion molecules were enriched as the most down-regulated DEPs. In protein–protein interaction analysis, the three hub targets in the up-regulated DEPs were α-1-antitrypsin, β-2-microglobulin and angiotensinogen, and the three key down-regulated DEPs were growth arrest-specific protein 6, matrix metalloproteinase-9 and urokinase-type plasminogen activator.

Conclusion: Urinary protein disorder was observed in CSA-AKI due to ischaemia and reperfusion. The application of Gemini C18 silica microspheres can improve the protein identification rate to obtain highly valuable resources for the urinary DEPs of AKI. This work provides valuable knowledge about urinary proteome biomarkers and essential resources for further research on AKI.

Updated Pathways in Cardiorenal Continuum after Kidney Transplantation

Cardiovascular disease (CVD) remains one of the leading causes for increased morbidity and mortality in chronic kidney disease (CKD). Kidney transplantation is the preferred treatment option for CKD G5. Improved perioperative and postoperative care, personalized immunosuppressive regimes, and refined matching procedures of kidney transplants improves cardiovascular health in the early posttransplant period. However, the long-term burden of CVD is considerable. Previously underrecognized, the role of the complement system alongside innate immunity, inflammaging, structural changes in the glomerular filtration barrier and early vascular ageing also seem to play an important role in the posttransplant management. This review provides up-to-date knowledge on these pathways that may influence the cardiovascular and renal continuum and identifies potential targets for future therapies. Arterial destiffening strategies and the applicability of sodium-glucose cotransporter 2 inhibitors and their role in cardiovascular health after kidney transplantation are also addressed.

Use of Ultra High Performance Liquid Chromatography with High Resolution Mass Spectrometry to Analyze Urinary Metabolome Alterations Following Acute Kidney Injury in Post-Cardiac Surgery Patients

•

Cardiac surgery-associated AKI results in dramatic changes in urinary metabolome.

•

Urinary metabolite disorder observed in patients with cardiac surgery-associated AKI.

•

When metaboloite disorder was due to ischaemia and medical treatment, kidneys could return to normal.

•

This work provides data about urinary metabolic profiles and resources for further research on AKI.

Background

Cardiac surgery-associated acute kidney injury (AKI) can increase the mortality and morbidity, and the incidence of chronic kidney disease, in critically ill survivors. The purpose of this research was to investigate possible links between urinary metabolic changes and cardiac surgery-associated AKI.

Methods

Using ultra-high-performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry, non-targeted metabolomics was performed on urinary samples collected from groups of patients with cardiac surgery-associated AKI at different time points, including Before_AKI (uninjured kidney), AKI_Day1 (injured kidney) and AKI_Day14 (recovered kidney) groups. The data among the three groups were analyzed by combining multivariate and univariate statistical methods, and urine metabolites related to AKI in patients after cardiac surgery were screened. Altered metabolic pathways associated with cardiac surgery-induced AKI were identified by examining the Kyoto Encyclopedia of Genes and Genomes database.

Results

The secreted urinary metabolome of the injured kidney can be well separated from the urine metabolomes of uninjured or recovered patients using multivariate and univariate statistical analyses. However, urine samples from the AKI_Day14 and Before_AKI groups cannot be distinguished using either of the two statistical analyses. Nearly 4000 urinary metabolites were identified through bioinformatics methods at Annotation Levels 1–4. Several of these differential metabolites may also perform essential biological functions. Differential analysis of the urinary metabolome among groups was also performed to provide potential prognostic indicators and changes in signalling pathways. Compared with the uninjured kidney group, the patients with cardiac surgery-associated AKI displayed dramatic changes in renal metabolism, including sulphur metabolism and amino acid metabolism.

Conclusions

Urinary metabolite disorder was observed in patients with cardiac surgery-associated AKI due to ischaemia and medical treatment, and the recovered patients’ kidneys were able to return to normal. This work provides data on urine metabolite markers and essential resources for further research on AKI.

Assessment of 17 clinically available renal biomarkers to predict acute kidney injury in critically ill patients

Background:

Systematic estimation of renal biomarkers in the intensive care unit (ICU) patients is lacking. Seventeen biomarkers were assessed to predict acute kidney injury (AKI) after admission to ICU.

Materials and methods:

A prospective, observational study was conducted in the general ICU of Guangdong Provincial People’s Hospital. Seventeen serum or urine biomarkers were studied for their abilities alone or in combination for predicting AKI and severe AKI.

Results:

Of 1498 patients, 376 (25.1%) developed AKI. Serum cystatin C (CysC) showed the best performance for predicting both AKI (area under the receiver operator characteristic curve [AUC] = 0.785, mean square error [MSE] = 0.118) and severe AKI (AUC = 0.883, MSE = 0.06). Regarding biomarkers combinations, CysC plus N-acetyl-β-d-glucosaminidase-to-creatinine ratio (NAG/Cr) was the best for predicting AKI (AUC = 0.856, MSE = 0.21). At the same time, CysC plus lactic acid (LAC) performed the best for predicting severe AKI (AUC = 0.907, MSE = 0.058). Regarding combinations of biomarkers and clinical markers, CysC plus Acute Physiology and Chronic Health Evaluation (APACHE) II score showed the best performance for predicting AKI (AUC = 0.868, MSE = 0.407). In contrast, CysC plus Multiple Organ Dysfunction Score (MODS) had the highest predictive ability for severe AKI (AUC = 0.912, MSE = 0.488).

Conclusion:

Apart from CysC, the combination of most clinically available biomarkers or clinical markers does not significantly improve the forecasting ability, and the cost–benefit ratio is not economical.

Assessment of kidney function: clinical indications for measured GFR

In the vast majority of cases, glomerular filtration rate (GFR) is estimated using serum creatinine, which is highly influenced by age, sex, muscle mass, body composition, severe chronic illness and many other factors. This often leads to misclassification of patients or potentially puts patients at risk for inappropriate clinical decisions. Possible solutions are the use of cystatin C as an alternative endogenous marker or performing direct measurement of GFR using an exogenous marker such as iohexol. The purpose of this review is to highlight clinical scenarios and conditions such as extreme body composition, Black race, disagreement between creatinine- and cystatin C-based estimated GFR (eGFR), drug dosing, liver cirrhosis, advanced chronic kidney disease and the transition to kidney replacement therapy, non-kidney solid organ transplant recipients and living kidney donors where creatinine-based GFR estimation may be invalid. In contrast to the majority of literature on measured GFR (mGFR), this review does not include aspects of mGFR for research or public health settings but aims to reach practicing clinicians and raise their understanding of the substantial limitations of creatinine. While including cystatin C as a renal biomarker in GFR estimating equations has been shown to increase the accuracy of the GFR estimate, there are also limitations to eGFR based on cystatin C alone or the combination of creatinine and cystatin C in the clinical scenarios described above that can be overcome by measuring GFR with an exogenous marker. We acknowledge that mGFR is not readily available in many centres but hope that this review will highlight and promote the expansion of kidney function diagnostics using standardized mGFR procedures as an important milestone towards more accurate and personalized medicine.