Proenkephalin Predicts Organ Failure, Renal Replacement Therapy, and Mortality in Patients With Sepsis

Current role of biomarkers in the initiation and weaning of kidney replacement therapy in acute kidney injury

The occurrence of acute kidney injury (AKI) in critically ill patients is often associated with increased morbidity and mortality rates. Despite extensive research, a consensus is yet to be arrived, especially regarding the optimal timing and indications for initiation of kidney replacement therapy (KRT) for critically ill patients. There is no clear guidance available on the timing of weaning from KRT. More recently, various biomarkers have produced promising prognostic prediction in such patients, regarding the need for KRT and its termination. Most of these biomarkers are indicative of kidney damage and stress, rather than recovery. However, large-scale validation studies are required to guide the cutoff values of these biomarkers among different patient cohorts so as to identify the optimum timing for KRT. This article reviews the kidney biomarkers in detail and summarizes the individual roles of biomarkers in the decision-making process for initiation and termination of the KRT among critically ill AKI patients and the supportive literature.

Current and novel biomarkers in cardiogenic shock

Cardiogenic shock (CS) carries a 30-50% in-hospital mortality rate, with little improvement in outcomes in the last decade. Challenges in improving outcomes are closely linked to the frequent late presentation or diagnosis of CS where the 'point of no return' has often passed, leading to haemodynamic dysregulation, progressive myocardial depression, hypotension, and a downward spiral of hypoperfusion, organ dysfunction and decreasing myocardial function, driven by inflammation and metabolic derangements. Novel therapeutic interventions may have varying efficacy depending on the type and stage of shock in which they are applied. Biomarkers that aid prediction and early detection of CS, provide early signs of organ dysfunction and define prognosis could help optimize management. Temporal change in such biomarkers, particularly in response to pharmacological interventions and/or mechanical circulatory support, can guide management and predict outcome. Several novel biomarkers enhance the prediction of mortality in CS, compared to conventional parameters such as lactate, with some, such as adrenomedullin and circulating dipeptidyl peptidase 3, also able to predict the development of CS. Some biomarkers reflect systemic inflammation (e.g. interleukin-6, angiopoietin 2, fibroblast growth factor 23 and suppressor of tumorigenicity 2) and are not specific to CS, yet inform on the activation of important pathways involved in the downward shock spiral. Other biomarkers signal end-organ hypoperfusion and could guide targeted interventions, while some may serve as novel therapeutic targets. We critically review current and novel biomarkers that guide prediction, detection, and prognostication in CS. Future use of biomarkers may help improve management in these high-risk patients.

Diagnostic and Prognostic Utilities of Pancreatic Stone Protein in Patients with Suspected Sepsis

Background/Objectives: Pancreatic stone protein (PSP) is an emerging biomarker of sepsis that is secreted from pancreas sensing remote organ damages. We explored the diagnostic and prognostic utilities of PSP in patients with suspected sepsis. Methods: In a total of 285 patients (suspected sepsis, n = 148; sepsis, n = 137), we compared PSP with procalcitonin (PCT) and sequential organ failure assessment (SOFA) score. Sepsis diagnoses were explored using receiver operating characteristic curve analyses with area under the curves (AUCs). Clinical outcomes (in-hospital mortality, 30-day mortality, and kidney replacement therapy [KRT]) were explored using the Kaplan-Meier method and a multivariate analysis with hazard ratio (HR). Results: PCT and PSP were comparable for sepsis diagnosis (AUC = 0.71-0.72, p < 0.001). The sepsis proportion was significantly higher when both biomarkers increased than when either one or both biomarkers did not increase (89.0% vs. 21.3-47.7%, p < 0.001). Each biomarker quartile (Q1-Q4) differed significantly according to their SOFA score (all p < 0.001). Compared with Q1, the Q2-Q4 groups showed worse clinical outcomes (p = 0.002-0.041). Both biomarkers added to the SOFA score showed higher HRs than the SOFA score alone (3.3-9.6 vs. 2.8-4.2, p < 0.001-0.011), with nearly 2.5-fold higher HR (9.6 vs. 4.2) for predicting KRT. Conclusions: Although PCT and PSP did not independently predict clinical outcomes in the multivariate analysis, PSP demonstrated diagnostic and prognostic utilities in patients with suspected sepsis, especially for predicting kidney dysfunction. PSP, alone or in combination with PCT, would be a valuable tool that can be added to clinical assessments.

Point-of-Care Serum Proenkephalin as an Early Predictor of Mortality in Patients Presenting to the Emergency Department with Septic Shock

BACKGROUND

The aim of the present study is to investigate the prognostic utility of point-of-care (POC)-measured proenkephalin (PENK), a novel biomarker, in terms of predicting in-hospital mortality in patients presenting to the emergency department (ED) with septic shock.

METHODS

Bedside PENK was measured in consecutive patients presenting to the ED with septic shock according to the Sepsis-3 clinical criteria. The association of PENK with inflammatory and routine biomarkers, and its role as a predictor of in-hospital mortality, was examined.

RESULTS

Sixty-one patients with septic shock [53% females, median age 83 years (IQR 71-88)] were evaluated. Median (IQR) values of creatinine, plasma lactate, soluble urokinase plasminogen activator receptor (SuPAR), procalcitonin and PENK were 1.7 (1.0-2.9) mg/dL, 3.6 (2.1-6.8) mmol/L, 13.1 (10.0-21.4) ng/mL, 2.06 (0.84-3.49) ng/mL, and 205 (129-425) pmol/L, respectively. LogPENK significantly correlated with LogLactate (rho = 0.369, p = 0.004), LogCreatinine (rho = 0.537, p < 0.001), LogProcalcitonin (rho = 0.557, p < 0.001), and LogSuPAR (rho = 0.327, p = 0.011). During hospitalization, 39/61 (64%) patients died. In a multivariable logistic regression model, logPENK was an independent predictor of in-hospital mortality (OR 11.9, 95% CI: 1.7-84.6, p = 0.013).

CONCLUSION

POC PENK levels measured upon presentation to the ED strongly correlated with metabolic, renal and inflammatory biomarkers, and may serve as a predictor of in-hospital mortality in patients with septic shock.

Proenkephalin Levels and Its Determinants in Patients with End-Stage Kidney Disease Treated with Hemodialysis and Peritoneal Dialysis

Recently, proenkephalin A (PENK A) has been shown to reflect glomerular dysfunction and to predict new-onset acute kidney injury and heart failure. While previous studies have investigated PENK A as a biomarker in individuals with preserved renal function, PENK A concentration in patients with end-stage kidney disease (ESKD) was not investigated. Plasma PENK A concentration was assessed in 88 patients with ESKD treated with hemodialysis (HD) or peritoneal dialysis (PD), and its associations with kidney function and heart failure indicators were investigated. In HD patients, the difference in PENK A levels before and after hemodialysis, was measured and further assessed for an association with the type of HD membrane used. PENK A levels did not differ significantly between HD and PD patients. In HD patients, the median PENK A concentration was significantly higher before than after hemodialysis (1.368 vs. 2.061, p = 0.003). No correlation was found between PENK A level and urea (p = 0.192), eGFR (p = 0.922), dialysis vintage (p = 0.637), and residual urine output (p = 0.784). Heart failure (p = 0.961), EF (p = 0.361), and NT-proBNP (p = 0.949) were not associated with increased PENK A concentration. PENK A does not reflect renal function and cardiac status in patients with ESKD. Further research is required to establish the clinical utility of the new biomarker in patients with impaired kidney function.

30 Days Mortality Prognostic Value of POCT Bio-Adrenomedullin and Proenkephalin in Patients with Sepsis in the Emergency Department

Background and Objective: Sepsis is a worldwide severe disease with a high incidence and mortality rate. Sepsis is a frequent cause of admission to the emergency department (ED). Although prognostic scores (Sequential Organ Failure Assessment, SOFA; New Early Warning Score, NEWS; Rapid Emergency Medicine Score, REMS) are commonly used for risk stratification in septic patients, many of these scores are of poor utility in the ED. In this setting, biomarkers are promising alternatives, easier to perform and potentially more specific. Bio-adrenomedullin (Bio-ADM) and Proenkephalin (PenKid) seem to have a key role in the development of organ dysfunctions induced by sepsis and, therefore, could help in the risk stratification of patients with sepsis at ED admission. The aim of this study was to evaluate the utility of Bio-ADM and PenKid, obtained through a point of care (POCT) device, in predicting 30 days mortality for patients presenting to the ED with sepsis. Methods and Results: In total, 177 consecutive adult patients with a diagnosis of sepsis presenting to the ED of San Giovanni Addolorata Hospital in Rome, Italy, between May 2021 and April 2022 were enrolled in this prospective observational study. For each patient, Bio-ADM and PenKid were obtained at ED admission together with SOFA, NEWS and REMS scores. Next, 30 days follow-up data were collected to evaluate patient mortality. Both biomarkers (Bio-ADM and PenKid) and clinical scores (SOFA, NEWS and REMS) were good predictors of mortality at 30 days, with Bio-ADM and REMS outperforming the others. Moreover, PenKid resulted in being linked with the worsening of kidney function. Conclusions: In patients presenting with sepsis in the ED, Bio-ADM and PenKid, evaluated with a POCT device, predicted 30-day mortality. These two biomarkers seem even more useful when integrated with clinical risk scores at ED admission.

Reference Interval for the Axis-Shield Clinical Chemistry Heparin-Binding Protein Assay

The newly developed Axis-Shield clinical chemistry heparin-binding protein (HBP) assay (Axis-Shield Diagnostics Ltd., Dundee, Scotland) can be applied to fully automated platforms. We aimed to establish a reference interval (RI) of HBP using the Axis-Shield HBP assay, and to evaluate the analytical performance of this assay. An RI was established in 212 sodium citrated plasma samples using the non-parametric method (2.5th and 97.5th percentiles). Precision, linearity, and carry-over were evaluated according to the Clinical and Laboratory Standards Institute guidelines. The RI of HBP was between 5.3 ng/mL and 171.0 ng/mL, which could be applied regardless of gender and age. Percentage coefficients of variations (%CVs) of repeatability and within-laboratory precision were 4.9% and 6.3%, respectively, for low-concentration control and 1.6% and 3.0%, respectively, for high-concentration control. The linearity was excellent (coefficient of determination (R²) = 0.99), and the carry-over rate was negligible (0.05%). This is the first study to establish an RI of HBP using the newly developed and fully automated Axis-Shield HBP assay. The Axis-Shield HBP assay showed an acceptable level of analytical performance and could be used to measure HBP concentrations effectively in routine clinical practice. Further studies are awaited to evaluate the clinical utility of HBP using this automated assay.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Analytical and clinical performance of the Advansure i3 procalcitonin assay

Procalcitonin (PCT) is a clinically useful biomarker for early diagnosis and subsequent management of sepsis. We evaluated the analytical performance of a new automated chemiluminescent immunoanalyzer-based procalcitonin assay, AdvanSure i3 PCT assay (LG Life Sciences, Korea) on an AdvanSure i3 (LG Life Sciences) and compared it to the Elecsys BRAHMS PCT assay (Roche, Switzerland) on a Cobas e801 (Roche). Analytical performance was performed for the precision, linearity, and method comparison with the Elecsys BRAHMS PCT assay by Clinical and Laboratory Standards Institute guidelines. Clinical evaluations were conducted using 87 residual samples from admitted patients with suspected infection. The patients were classified based on Sepsis-3 classification. The AdvanSure i3 PCT assay exhibited a CV <5.5% for between-run precision and <6.5% for within-laboratory precision. The assay was linear up to 80.32 µg/L (r = 0.990). Statistical analysis showed that the two assays yielded a good correlation (r = 0.996), with a weighted kappa value of 0.94. Median plasma PCT level was significantly different between the non-sepsis and sepsis groups (p < .001) and the non-sepsis and septic shock groups (p < .0018). The AdvanSure i3 PCT assay showed good analytical performance and correlation with the Elecsys BRAHMS PCT assay for the sepsis patients. This new assay can be used as a diagnostic early marker of sepsis in clinical laboratories.

Biomarker-Guided Risk Assessment for Acute Kidney Injury: Time for Clinical Implementation?

Acute kidney injury (AKI) is a common and serious complication in hospitalized patients, which continues to pose a clinical challenge for treating physicians. The most recent Kidney Disease Improving Global Outcomes practice guidelines for AKI have restated the importance of earliest possible detection of AKI and adjusting treatment accordingly. Since the emergence of initial studies examining the use of neutrophil gelatinase-associated lipocalin (NGAL) and cycle arrest biomarkers, tissue inhibitor metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein (IGFBP7), for early diagnosis of AKI, a vast number of studies have investigated the accuracy and additional clinical benefits of these biomarkers. As proposed by the Acute Dialysis Quality Initiative, new AKI diagnostic criteria should equally utilize glomerular function and tubular injury markers for AKI diagnosis. In addition to refining our capabilities in kidney risk prediction with kidney injury biomarkers, structural disorder phenotypes referred to as "preclinical-" and "subclinical AKI" have been described and are increasingly recognized. Additionally, positive biomarker test findings were found to provide prognostic information regardless of an acute decline in renal function (positive serum creatinine criteria). We summarize and discuss the recent findings focusing on two of the most promising and clinically available kidney injury biomarkers, NGAL and cell cycle arrest markers, in the context of AKI phenotypes. Finally, we draw conclusions regarding the clinical implications for kidney risk prediction.