Urinary [TIMP-2] × [IGFBP7] and serum procalcitonin to predict and assess the risk for short-term outcomes in septic and non-septic critically ill patients

Predictive performance of two types of urinary biomarkers for renal non-recovery in sepsis-associated acute kidney injury: a prospective observational study

BACKGROUND AND PURPOSE

Renal non-recovery is known to have negative prognostic implications in patients suffering from acute kidney injury (AKI). Nevertheless, the identification of biomarkers for predicting renal non-recovery in sepsis-associated AKI (SA-AKI) within clinical settings remains unresolved. This study aims to evaluate and compare the predictive ability for renal non-recovery, use of kidney replacement therapy (KRT) in the Intensive Care Unit (ICU), and 30-day mortality after SA-AKI by two urinary biomarkers, namely C-C motif chemokine ligand 14 (CCL14) and [TIMP-2]•[IGFBP7].

METHODS

We prospectively screened adult patients who met the criteria for AKI stage 2-3 and Sepsis-3.0 in two ICUs from January 2019 to May 2022. Patients who developed new-onset SA-AKI after ICU admission were enrolled and urinary biomarkers including [TIMP-2]•[IGFBP7] and CCL14 were detected at the time of SA-AKI diagnosis. The primary endpoint was non-recovery from SA-AKI within 7 days. The secondary endpoints were the use of KRT in the ICU and 30-day mortality after SA-AKI. The individual discriminative ability of [TIMP-2]•[IGFBP7] and CCL14 to predict renal non-recovery were evaluated by the area under receiver operating characteristics curve (AUC).

RESULTS

141 patients with stage 2-3 SA-AKI were finally included, among whom 54 (38.3%) experienced renal non-recovery. Urinary CCL14 exhibited a higher predictive capability for renal non-recovery compared to [TIMP-2]•[IGFBP7], with CCL14 showing an AUC of 0.901, versus an AUC of 0.730 for [TIMP-2]•[IGFBP7] (P = 0.001). Urinary CCL14 and [TIMP-2]•[IGFBP7] demonstrated a moderate predictive value for the need for KRT in ICU, with AUC values of 0.794 and 0.725, respectively; The AUC of [TIMP-2]•[IGFBP7] combined with CCL14 reached up to 0.816. Urinary CCL14 and [TIMP-2]•[IGFBP7] exhibited poor predictive power for 30-day mortality, with respective AUC values of 0.623 and 0.593.

CONCLUSION

Urinary CCL14 had excellent predictive value for renal non-recovery in SA-AKI patients. For predicting the use of KRT in the ICU, the predictive capability of urinary [TIMP-2]•[IGFBP7] or CCL14 was fair. However, a combination of [TIMP-2]•[IGFBP7] and CCL14 showed good predictive ability for the use of KRT.

The predictive value of [TIMP-2]*[IGFBP7] in adverse outcomes for acute kidney injury: a systematic review and meta-analysis

MATERIALS AND METHODS

Relevant articles published up to 17 June 2023 were retrieved from five databases (Cochrane Library/Embase/PubMed/SinoMed/Web of Science). The pre-established inclusion and exclusion criteria determined the selection of publications. Pooled sensitivity (SEN), specificity (SPE), diagnostic odds ratio, likelihood ratio, and summary receiver operating characteristic curve were employed to assess the predictive value. The presence or potential sources of heterogeneity were investigated via subgroup and SEN analyses.

RESULTS

Ten published and eligible studies (1559 cases) were included in the evaluation for the capability of [TIMP-2]*[IGFBP7] to predict the poor prognosis of AKI through the random effect model. Pooled SEN, SPE, diagnostic odds ratio, and positive and negative likelihood ratios were 0.82 (95% CI: 0.77-0.86, I2 = 53.4%), 0.64 (95% CI: 0.61-0.67, I2 = 88.3%), 14.06 (95% CI: 7.31-27.05, I2 = 55.0%), 2.859 (95% CI: 2.15-3.77, I2 = 80.7%), and 0.28 (95% CI: 0.20-0.40, I2 = 35.0%), respectively. The estimated area under the curve was 0.8864 (standard error: 0.0306), and the Q* was 0.7970 (standard error: 0.0299). The endpoints and cutoff values were the main causes of heterogeneity.

CONCLUSIONS

[TIMP-2]*[IGFBP7] is possible in predicting poor prognosis of AKI, but it is better to be applied along with other indicators or clinical risk factors.

The early diagnosis and pathogenic mechanisms of sepsis-related acute kidney injury

Sepsis is a syndrome caused by an imbalance in the inflammatory response of the body caused by an infection that leads to organ dysfunction, with the kidney being one of the most commonly affected organs. Sepsis-related acute kidney injury (SAKI) is strongly linked to increased mortality and poor clinical outcomes. Early diagnosis and treatment can significantly reduce patient mortality. On the other hand, the pathogenesis of SAKI is not fully understood, and early diagnosis of SAKI is a clinical challenge. Therefore, the current review describes biomarkers of acute kidney injury in sepsis and discusses the various pathogenic mechanisms involved in the progression of acute kidney injury in sepsis to develop new clinical treatment avenues.

Auto- and paracrine rewiring of NIX-mediated mitophagy by insulin-like growth factor-binding protein 7 in septic AKI escalates inflammation-coupling tubular damage

AIMS

Inflammation-coupling tubular damage (ICTD) contributes to pathogenesis of septic acute kidney injury (AKI), in which insulin-like growth factor-binding protein 7 (IGFBP-7) serves as a biomarker for risk stratification. The current study aims to discern how IGFBP-7 signalling influences ICTD, the mechanisms that underlie this process and whether blockade of the IGFBP-7-dependent ICTD might have therapeutic value for septic AKI.

MATERIALS AND METHODS

In vivo characterization was carried out in B6/JGpt-Igfbp7^em1Cd1165/Gpt mice subjected to cecal ligation and puncture (CLP). Transmission electron microscopy, immunofluorescence, flow cytometry, immunoblotting, ELISA, RT-qPCR and dual-luciferase reporter assays were used to determine mitochondrial functions, cell apoptosis, cytokine secretion and gene transcription.

KEY FINDINGS

ICTD augments the transcriptional activity and protein secretion of tubular IGFBP-7, which enables an auto- and paracrine signalling via deactivation of IGF-1 receptor (IGF-1R). Genetic knockout (KO) of IGFBP-7 provides renal protection, improves survival and resolves inflammation in murine models of cecal ligation and puncture (CLP), while administering recombinant IGFBP-7 aggravates ICTD and inflammatory invasion. IGFBP-7 perpetuates ICTD in a NIX/BNIP3-indispensable fashion through dampening mitophagy that restricts redox robustness and preserves mitochondrial clearance programs. Adeno-associated viral vector 9 (AAV9)-NIX short hairpin RNA (shRNA) delivery ameliorates the anti-septic AKI phenotypes of IGFBP-7 KO. Activation of BNIP3-mediated mitophagy by mitochonic acid-5 (MA-5) effectively attenuates the IGFBP-7-dependent ICTD and septic AKI in CLP mice.

SIGNIFICANCE

Our findings identify IGFBP-7 is an auto- and paracrine manipulator of NIX-mediated mitophagy for ICTD escalation and propose that targeting the IGFBP-7-dependent ICTD represents a novel therapeutic strategy against septic AKI.

Kinetics of the Cell Cycle Arrest Biomarkers (TIMP2 and IGFBP7) for the Diagnosis of Acute Kidney Injury in Critically Ill COVID-19 Patients

BACKGROUND

Acute kidney injury (AKI) is highly prevalent in critical COVID-19 patients. The diagnosis and staging of AKI are based on serum creatinine (sCr) and urinary output criteria, with limitations in the functional markers. New cell-cycle arrest biomarkers [TIMP2]*[IGFBP7] have been proposed for early detection of AKI, but their role in critically ill COVID-19 patients is poorly understood.

METHODS

We conducted an observational study to assess the performance of [TIMP2]*[IGFBP7] for the detection of AKI in critical COVID-19 patients admitted to our intensive care unit (ICU). We sampled urinary [TIMP2]*[IGFBP7] levels at ICU admission, 12 h, 24 h, and 48 h, and compared the results to the development of AKI, as well as baseline and laboratory data.

RESULTS

Forty-one patients were enrolled. The median age was 66 years [57-72] and most were males (85%). Thirteen patients (31.7%) developed no/mild stage AKI, 19 patients (46.3%) moderate AKI, and nine patients (22.0%) severe AKI. The ICU mortality was 29.3%. sCr levels in the Emergency Department or at ICU admission were not significantly different according to AKI stage. [TIMP-2]*[IGFBP-7] urinary levels were elevated in severe AKI at 12 h after ICU admission, but not at ICU admission or 24 h or 48 h after ICU admission.

CONCLUSION

Urinary biomarkers [TIMP-2]*[IGFBP-7] were generally increased in this population with a high prevalence of AKI, and were higher in patients with severe AKI measured at 12 h from ICU admission. Further studies are needed to evaluate the best timing of these biomarkers in this population.

Proficient Novel Biomarkers Guide Early Detection of Acute Kidney Injury: A Review

The definition of acute kidney injury (AKI), despite improvements in criteria, continues to be based on the level of serum creatinine and urinary output that do not specifically indicate tubular function or injury, or glomerular function or injury that is not significant enough to warrant acute hospitalization of the patient. Finding novel biomarkers of AKI has become a major focus nowadays in nephrology to overcome the further complications of end stage renal disease (ESRD). Many compounds, such as KIM 1, IL 18, NGAL, uromodulin, calprotectin, vanin 1, galactin 3, platelet-derived growth factor (PDGF), urinary Na⁺/H⁺ exchanger isoform 3 (NHE3), retinol binding protein (RBP) and Cystatin C, are released from the renal tubules and thus any alterations in tubular function can be detected by measuring these parameters in urine. Additionally, glomerular injury can be detected by measuring immunoglobulin G, nephrin, podocalyxin, podocin, transferrin, netrin-1, pyruvate kinase M2, etc. in urine. These novel biomarkers will be useful for timing the initial insult and assessing the duration of AKI. According to available research, these biomarkers could be applied to assess the onset of AKI, distinguishing between kidney injury and dysfunction, directing the management of AKI, and enhancing disease diagnosis. Therefore, we intend to present recent developments in our understanding of significant biomarkers implicated in various aspects of renal damage. Numerous biomarkers are implicated in various pathophysiological processes that follow renal injury, and can improve prognosis and risk classification.

Evaluation of acute kidney injury by urinary tissue inhibitor metalloproteinases-2 and insulin-like growth factor-binding protein 7 after pediatric cardiac surgery

BACKGROUND

With adult patients, the measurement of [TIMP-2]*[IGFBP7] can predict the risk of moderate to severe AKI within 12 h of testing. In pediatrics, however, the performance of [TIMP-2]*[IGFBP7] as a predictor of AKI was less studied and yet to be widely utilized in clinical practice. This study was conducted to validate the utility of [TIMP-2]*[IGFBP7] as an earlier biomarker for AKI prediction in Chinese infants and small children.

METHODS

We measured urinary [TIMP-2]*[IGFBP7] using NEPHROCHECK® at eight perioperative time points in 230 patients undergoing complex cardiac surgery and evaluated the performance of [TIMP-2]*[IGFBP7] for predicting severe AKI within 72 h of surgery.

RESULTS

A total of 50 (22%) of 230 developed AKI stages 2-3 within 72 h after CPB initiation. In the AKI stage 2-3 patients, two patterns of serum creatinine (SCr) elevations were observed. The patients with only a transient increase in SCr within 24 h (< 24 h, early AKI 2-3) did not experience a worse outcome than patients in AKI stage 0-1. AKI stage 2-3 patients with SCr elevation after 24 h (24-72 h, late AKI 2-3), as well as AKI dialysis patients (together designated severe AKI), did experience worse outcomes. Compared to AKI stages 0-1, significant elevations of [TIMP-2]*[IGFBP7] values were observed in severe AKI patients at hours T2, T4, T12, and T24 following CPB initiation. The AUC for predicting severe AKI with [TIMP-2]*[IGFBP7] at T2 (AUC = 0.76) and maximum T2/T24 (AUC = 0.80) are higher than other time points. The addition of the NEPHROCHECK® test to the postoperative parameters improved the risk assessment of severe AKI.

CONCLUSIONS

Multiple AKI phenotypes (early versus late AKI) were identified after pediatric complex cardiac surgery according to SCr-based AKI definition. Urinary [TIMP-2]*[IGFBP7] predicts late severe AKI (but not early AKI) as early as 2 h following CPB initiation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Advances in laboratory detection of acute kidney injury

Recent advances have improved our understanding of the epidemiology and pathophysiology of acute kidney injury (AKI). So far, the Kidney Disease: Improving Global Outcome guidelines define and stratify kidney injury based on increases in serum creatinine level and/or decreases in urine output. Although the term AKI acknowledges the existence of cellular injury, its diagnosis is still only defined by the reduced excretory function of the kidney. New biomarkers that aid a better understanding of the relationship between acute tubular injury and kidney dysfunction have been identified, reflecting the advances in molecular biology. The expression of some of these novel biomarkers precedes changes in conventional biomarkers or can increase their predictive power. Therefore, they might enhance the clinical accuracy of the definition of AKI. This review summarizes the limitations of the current AKI classification and a panel of candidate biomarkers for augmenting AKI classification and recognition of AKI subphenotypes. We expect that the integration of appropriately selected biomarkers in routine clinical practice can improve AKI care.

Prognostic Value of Systemic Immune-Inflammation Index among Critically Ill Patients with Acute Kidney Injury: A Retrospective Cohort Study

Inflammation plays a significant role in the occurrence and development of acute kidney injury (AKI). Evidence regarding the prognostic effect of the systemic immune-inflammation index (SII) in critically ill patients with AKI is scarce. The aim of this study was to assess the association between SII and all-cause mortality in these patients. Detailed clinical data were extracted from the Medical Information Mart for Intensive Care Database (MIMIC)-IV. The primary outcome was set as the in-hospital mortality. A total of 10,764 AKI patients were enrolled in this study. The restricted cubic splines analyses showed a J-shaped curve between SII and the risk of in-hospital and ICU mortality. After adjusting for relevant confounders, multivariate Cox regression analysis showed that both lower and higher SII levels were associated with an elevated risk of in-hospital all-cause mortality. A similar trend was observed for ICU mortality. In summary, we found that the SII was associated in a J-shaped pattern with all-cause mortality among critically ill patients with AKI. SII appears to be have potential applications in the clinical setting as a novel and easily accessible biomarker for predicting the prognosis of AKI patients.

Update on prognosis driven classification of pediatric AKI

Acute kidney injury (AKI) affects a large proportion of hospitalized children and increases morbidity and mortality in this population. Initially thought to be a self-limiting condition with uniformly good prognosis, we now know that AKI can persist and progress to acute kidney disease (AKD) and chronic kidney disease (CKD). AKI is presently categorized by stage of injury defined by increase in creatinine, decrease in eGFR, or decrease in urine output. These commonly used biomarkers of acute kidney injury do not change until the injury is well established and are unable to detect early stage of the disease when intervention is likely to reverse injury. The kidneys have the ability to compensate and return serum creatinine to a normal or baseline level despite nephron loss in the setting of AKI possibly masking persistent dysfunction. Though these definitions are important, classifying children by their propensity for progression to AKD and CKD and defining these risk strata by other factors besides creatinine may allow for better prognosis driven discussion, expectation setting, and care for our patients. In order to develop a classification strategy, we must first be able to recognize children who are at risk for AKD and CKD based on modifiable and non-modifiable factors as well as early biomarkers that identify their risk of persistent injury. Prevention of initial injury, prompt evaluation and treatment if injury occurs, and mitigating further injury during the recovery period may be important factors in decreasing risk of AKD and CKD after AKI. This review will cover presently used definitions of AKI, AKD, and CKD, recent findings in epidemiology and risk factors for AKI to AKD to CKD progression, novel biomarkers for early identification of AKI and AKI that may progress to CKD and future directions for improving outcome in children with AKI.

Predictive Ability of Procalcitonin for Acute Kidney Injury: A Narrative Review Focusing on the Interference of Infection

Acute kidney injury (AKI) is a common yet complicated clinical entity with high morbidity and mortality. An essential strategy to improve AKI patients’ prognoses is finding optimal biomarkers to identify AKI in a timely manner. Procalcitonin (PCT), a well-recognized biomarker for diagnosing infection and guiding antibiotics therapy, has been proposed to predict AKI development and recovery in many clinical settings. The current review provides comprehensive and updated information from relevant studies to evaluate PCT’s AKI-predictive ability and the influence of infection on this predictive ability. PCT has demonstrated optimal predictive ability for AKI in various populations irrespective of infection. However, the predictive ability seems to be blunted by infection since infection and inflammation have a more potent influence than AKI on PCT elevation. We furthermore explain the complicated association between elevated PCT levels and AKI in infection and inflammation situations and recommend directions for further investigations to clarify the essential issue. In conclusion, although conflicting data exist, serum PCT level is a potential biomarker for predicting AKI in many clinical settings regardless of infection. Nevertheless, further studies are warranted to clarify the association between PCT, infection, and AKI and to confirm the utilization of PCT for AKI prediction.

Epidemiology and Outcomes of Acute Kidney Diseases: A Comparative Analysis

INTRODUCTION

Acute kidney diseases and disorders (AKD) encompass acute kidney injury (AKI) and subacute or persistent alterations in kidney function that occur after an initiating event. Unlike AKI, accurate estimates of the incidence and prognosis of AKD are not available and its clinical significance is uncertain.

METHODS

We studied the epidemiology and long-term outcome of AKD (as defined by the KDIGO criteria), with or without AKI, in a retrospective cohort of adults hospitalized at a single centre for >24 h between 2012 and 2016 who had a baseline eGFR ≥60 mL/min/1.73 m2 and were alive at 30 days. In patients for whom follow-up data were available, the risks of major adverse kidney events (MAKEs), CKD, kidney failure, and death were examined by Cox and competing risk regression analyses.

RESULTS

Among 62,977 patients, 906 (1%) had AKD with AKI and 485 (1%) had AKD without AKI. Follow-up data were available for 36,118 patients. In this cohort, compared to no kidney disease, AKD with AKI was associated with a higher risk of MAKEs (40.25 per 100 person-years; hazard ratio [HR] 2.51, 95% confidence interval [CI] 2.16-2.91), CKD (27.84 per 100 person-years); subhazard ratio [SHR] 3.18, 95% CI 2.60-3.89), kidney failure (0.56 per 100 person-years; SHR 24.84, 95% CI 5.93-104.03), and death (14.86 per 100 person-years; HR 1.52, 95% CI 1.20-1.92). Patients who had AKD without AKI also had a higher risk of MAKEs (36.21 per 100 person-years; HR 2.26, 95% CI 1.89-2.70), CKD (22.94 per 100 person-years; SHR 2.69, 95% CI 2.11-3.43), kidney failure (0.28 per 100 person-years; SHR 12.63, 95% CI 1.48-107.64), and death (14.86 per 100 person-years; HR 1.57, 95% CI 1.19-2.07). MAKEs after AKD were driven by CKD, especially in the first 3 months.

CONCLUSIONS

These findings establish the burden and poor prognosis of AKD and support prioritisation of clinical initiatives and research strategies to mitigate such risk.

Use of Biomarkers to Identify Acute Kidney Injury to Help Detect Sepsis in Patients With Infection

OBJECTIVES

Although early recognition of sepsis is vital to improving outcomes, the diagnosis may be missed or delayed in many patients. Acute kidney injury is one of the most common organ failures in patients with sepsis but may not be apparent on presentation. Novel biomarkers for acute kidney injury might improve organ failure recognition and facilitate earlier sepsis care.

DESIGN

Retrospective, international, Sapphire study.

SETTING

Academic Medical Center.

PATIENTS

Adults admitted to the ICU without evidence of acute kidney injury at time of enrollment.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We stratified patients enrolled in the Sapphire study into three groups-those with a clinical diagnosis of sepsis (n = 216), those with infection without sepsis (n = 120), and those without infection (n = 387) at enrollment. We then examined 30-day mortality stratified by acute kidney injury within each group. Finally, we determined the operating characteristics for kidney stress markers (tissue inhibitor of metalloproteinases-2) × (insulin-like growth factor binding protein 7) for prediction of acute kidney injury as a sepsis-defining organ failure in patients with infection without a clinical diagnosis of sepsis at enrollment. Combining all groups, 30-day mortality was 23% for patients who developed stage 2-3 acute kidney injury within the first 3 days compared with 14% without stage 2-3 acute kidney injury. However, this difference was greatest in the infection without sepsis group (34% vs 11%; odds ratio, 4.09; 95% CI, 1.53-11.12; p = 0.005). Using a (tissue inhibitor of metalloproteinases-2) × (insulin-like growth factor binding protein 7) cutoff of 2.0 units, 14 patients (11.7%), in the infection/no sepsis group, tested positive of which 10 (71.4%) developed stage 2-3 acute kidney injury. The positive test result occurred a median of 19 hours (interquartile range, 0.8-34.0 hr) before acute kidney injury manifested by serum creatinine or urine output. Similar results were obtained using a cutoff of 1.0 for any stage of acute kidney injury.

CONCLUSIONS

Use of the urinary (tissue inhibitor of metalloproteinases-2) × (insulin-like growth factor binding protein 7) test could identify acute kidney injury in patients with infection, possibly helping to detect sepsis, nearly a day before acute kidney injury is apparent by clinical criteria.