Biomarkers in cardiogenic shock: old pals, new friends.

In cardiogenic shock, biomarkers should ideally help make the diagnosis, choose the right therapeutic options and monitor the patient in addition to clinical and echocardiographic indices. Among "old" biomarkers that have been used for decades, lactate detects, quantifies, and follows anaerobic metabolism, despite its lack of specificity. Renal and liver biomarkers are indispensable for detecting the effect of shock on organ function and are highly predictive of poor outcomes. Direct biomarkers of cardiac damage such as cardiac troponins, B-type natriuretic and N-terminal pro-B-type natriuretic peptides have a good prognostic value, but they lack specificity to detect a cardiogenic cause of shock, as many factors influence their plasma concentrations in critically ill patients. Among the biomarkers that have been more recently described, dipeptidyl peptidase-3 is one of the most interesting. In addition to its prognostic value, it could represent a therapeutic target in cardiogenic shock in the future as a specific antibody inhibits its activity. Adrenomedullin is a small peptide hormone secreted by various tissues, including vascular smooth muscle cells and endothelium, particularly under pathological conditions. It has a vasodilator effect and has prognostic value during cardiogenic shock. An antibody inhibits its activity and so adrenomedullin could represent a therapeutic target in cardiogenic shock. An increasing number of inflammatory biomarkers are also of proven prognostic value in cardiogenic shock, reflecting the inflammatory reaction associated with the syndrome. Some of them are combined to form prognostic proteomic scores. Alongside clinical variables, biomarkers can be used to establish biological "signatures" characteristic of the pathophysiological pathways involved in cardiogenic shock. This helps describe patient subphenotypes, which could in the future be used in clinical trials to define patient populations responding specifically to a treatment.

Alterations in the Renin-Angiotensin System in Experimental Septic Shock.

OBJECTIVES: To analyze dynamic changes in the renin-angiotensin system (RAS) during septic shock, focusing on angiotensin-converting enzyme (ACE) activity and the balance between angiotensin peptides, using a mass spectrometry method. DESIGN: Experimental septic shock model induced by peritonitis in swine. SETTING: Experimental Laboratory, Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles. SUBJECTS: Forty time points from eight mechanically ventilated pigs. INTERVENTIONS: Septic shock was induced using intraperitoneal instillation of autologous feces, followed by standardized fluid resuscitation, norepinephrine infusion, antibiotic administration, and peritoneal lavage. MEASUREMENTS AND MAIN RESULTS: The induction of sepsis resulted in a significant increase in plasma renin activity and levels of angiotensin I and II, with a significant decrease in ACE activity observed from 4 hours post-resuscitation and a notable rise in the angiotensin I/angiotensin II ratio at 12 hours. Additionally, a shift toward the angiotensin-(1-7) axis was observed, evidenced by an increased angiotensin-(1-7)/angiotensin II ratio. CONCLUSIONS: The study highlighted dynamic shifts in the RAS during septic shock, characterized by reduced circulating ACE activity, elevated angiotensin I/II ratio, and a shift toward the angiotensin-(1-7) axis. These findings suggest an adaptive response within the RAS, potentially offering new insights into sepsis management and therapeutic targets.

Impaired angiotensin II signaling in septic shock.

Recent years have seen a resurgence of interest for the renin-angiotensin-aldosterone system in critically ill patients. Emerging data suggest that this vital homeostatic system, which plays a crucial role in maintaining systemic and renal hemodynamics during stressful conditions, is altered in septic shock, ultimately leading to impaired angiotensin II-angiotensin II type 1 receptor signaling. Indeed, available evidence from both experimental models and human studies indicates that alterations in the renin-angiotensin-aldosterone system during septic shock can occur at three distinct levels: 1. Impaired generation of angiotensin II, possibly attributable to defects in angiotensin-converting enzyme activity; 2. Enhanced degradation of angiotensin II by peptidases; and/or 3. Unavailability of angiotensin II type 1 receptor due to internalization or reduced synthesis. These alterations can occur either independently or in combination, ultimately leading to an uncoupling between the renin-angiotensin-aldosterone system input and downstream angiotensin II type 1 receptor signaling. It remains unclear whether exogenous angiotensin II infusion can adequately address all these mechanisms, and additional interventions may be required. These observations open a new avenue of research and offer the potential for novel therapeutic strategies to improve patient prognosis. In the near future, a deeper understanding of renin-angiotensin-aldosterone system alterations in septic shock should help to decipher patients' phenotypes and to implement targeted interventions.

Inhibition of circulating dipeptidyl-peptidase 3 by procizumab in experimental septic shock reduces catecholamine exposure and myocardial injury.

BACKGROUND: Dipeptidyl peptidase 3 (DPP3) is a ubiquitous cytosolic enzyme released into the bloodstream after tissue injury, that can degrade angiotensin II. High concentrations of circulating DPP3 (cDPP3) have been associated with worse outcomes during sepsis. The aim of this study was to assess the effect of Procizumab (PCZ), a monoclonal antibody that neutralizes cDPP3, in an experimental model of septic shock. METHODS: In this randomized, open-label, controlled study, 16 anesthetized and mechanically ventilated pigs with peritonitis were randomized to receive PCZ or standard treatment when the mean arterial pressure (MAP) dropped below 50 mmHg. Resuscitation with fluids, antimicrobial therapy, peritoneal lavage, and norepinephrine was initiated one hour later to maintain MAP between 65-75 mmHg for 12 h. Hemodynamic variables, tissue oxygenation indices, and measures of organ failure and myocardial injury were collected. Organ blood flow was assessed using isotopic assessment (99mtechnetium albumin). cDPP3 activity, equilibrium analysis of the renin-angiotensin system and circulating catecholamines were measured. Tissue mRNA expression of interleukin-6 and downregulation of adrenergic and angiotensin receptors were assessed on vascular and myocardial samples. RESULTS: PCZ-treated animals had reduced cDPP3 levels and required less norepinephrine and fluid than septic control animals for similar organ perfusion and regional blood flow. PCZ-treated animals had less myocardial injury, and higher PaO2/FiO2 ratios. PCZ was associated with lower circulating catecholamine levels; higher circulating angiotensin II and higher angiotensin II receptor type 1 myocardial protein expression, and with lower myocardial and radial artery mRNA interleukin-6 expression. CONCLUSIONS: In an experimental model of septic shock, PCZ administration was associated with reduced fluid and catecholamine requirements, less myocardial injury and cardiovascular inflammation, along with preserved angiotensin II signaling.

High Circulating Dipeptidyl Peptidase 3 Predicts Mortality and Need for Organ Support in Cardiogenic Shock: An Ancillary Analysis of the ACCOST-HH Trial.

BACKGROUND: Cardiogenic shock (CS) is burdened with high mortality. Efforts to improve outcome are hampered by the difficulty of individual risk stratification and the lack of targetable pathways. Previous studies demonstrated that elevated circulating dipeptidyl peptidase 3 (cDPP3) is an early predictor of short-term outcome in CS, mostly of ischemic origin. Our objective was to investigate the association between cDPP3 and short-term outcomes in a diverse population of patients with CS. METHODS AND RESULTS: cDPP3 was measured at baseline and after 72 hours in the AdreCizumab against plaCebO in SubjecTs witH cardiogenic sHock (ACCOST-HH) trial. The association of cDPP3 with 30-day mortality and need for organ support was assessed. Median cDPP3 concentration at baseline was 43.2 ng/mL (95% confidence interval [CI], 21.2-74.0 ng/mL) and 77 of the 150 patients (52%) had high cDPP3 over the predefined cutoff of 40 ng/mL. Elevated cDPP3 was associated with higher 30-day mortality (adjusted hazard ratio [aHR] = 1.7; 95% CI, 1.0-2.9), fewer days alive without cardiovascular support (aHR, 3 days [95% CI, 0-24 days] vs aHR, 21 days [95% CI, 5-26 days]; P < .0001) and a greater need for renal replacement therapy (56% vs 22%; P < .0001) and mechanical ventilation (90 vs 74%; P = .04). Patients with a sustained high cDPP3 had a poor prognosis (reference group). In contrast, patients with an initially high but decreasing cDPP3 at 72 hours had markedly lower 30-day mortality (aHR, 0.17; 95% CI, 0.084-0.34), comparable with patients with a sustained low cDPP3 (aHR, 0.23; 95% CI, 0.12-0.41). The need for organ support was markedly decreased in subpopulations with sustained low or decreasing cDPP3. CONCLUSIONS: The present study confirms the prognostic value of cDPP3 in a contemporary population of patients with CS.

DPP3 promotes breast cancer tumorigenesis by stabilizing FASN and promoting lipid synthesis.

DPP3, a dipeptidyl peptidase, participates in a variety of pathophysiological processes. DPP3 is upregulated in cancer and might serve as a key factor in the tumorigenesis and progression of various malignancies. However, its specific role and molecular mechanism are still unknown. In this study, the expression of DPP3 in breast cancer tissues is analyzed using TCGA database. Kaplan-Meier survival analysis is performed to estimate the effect of DPP3 on the survival outcomes. To explore the biological function and mechanisms of DPP3 in breast cancer, biochemical and cell biology assays are conducted in vitro. DPP3 expresses at a higher level in breast cancer tissues than that in adjacent tissues in both TCGA database and clinical samples. Patients with high expression of DPP3 have poor survival outcomes. The proliferation and migration abilities of tumor cells with stable DPP3 knockout in breast cancer cell lines are significantly inhibited, and apoptosis is increased in vitro. GSEA analysis shows that DPP3 can affect lipid metabolism and fatty acid synthesis in tumors. Subsequent experiments show that DPP3 could stabilize FASN expression and thus promote fatty acid synthesis in tumor cells. The results of the metabolomic analysis also confirm that DPP3 can affect the content of free fatty acids. This study demonstrates that DPP3 plays a role in the reprogramming of fatty acid metabolism in tumors and is associated with poor prognosis in breast cancer patients. These findings will provide a new therapeutic target for the treatment of breast cancer.

The scientific rationale and study protocol for the DPP3, Angiotensin II, and Renin Kinetics in Sepsis (DARK-Sepsis) randomized controlled trial: serum biomarkers to predict response to angiotensin II versus standard-of-care vasopressor therapy in the treatment of septic shock.

BACKGROUND: Data to support the use of specific vasopressors in septic shock are limited. Since angiotensin II (AT2) was approved by the Food and Drug Administration in 2017, multiple mechanistically distinct vasopressors are available to treat septic shock, but minimal data exist regarding which patients are most likely to benefit from each agent. Renin and dipeptidyl peptidase 3 (DPP3) are components of the renin-angiotensin-aldosterone system which have been shown to outperform lactate in predicting sepsis prognosis, and preliminary data suggest they could prove useful as biomarkers to guide AT2 use in septic shock. METHODS: The DARK-Sepsis trial is an investigator-initiated industry-funded, open-label, single-center randomized controlled trial of the use of AT2 versus standard of care (SOC) vasopressor therapy in patients admitted to the intensive care unit (ICU) with vasodilatory shock requiring norepinephrine ≥ 0.1 mcg/kg/min. In both groups, a series of renin and DPP3 levels will be obtained over the first 24 h of treatment with AT2 or SOC. The primary study outcome will be the ability of these biomarkers to predict response to vasopressor therapy, as measured by change in total norepinephrine equivalent dose of vasopressors at 3 h post-drug initiation or the equivalent timepoint in the SOC arm. To determine if the ability to predict vasopressor response is specific to AT2 therapy, the primary analysis will be the ability of baseline renin and DPP3 levels to predict vasopressor response adjusted for treatment arm (AT2 versus control) and Sequential Organ Failure Assessment (SOFA) scores. Secondary outcomes will include rates of acute kidney injury, need for mechanical ventilation and kidney replacement therapy, lengths of stay in the ICU and hospital, ICU and hospital mortality, and rates of prespecified adverse events. DISCUSSION: With an armamentarium of mechanistically distinct vasopressor agents now available, sub-phenotyping patients using biomarkers has the potential to improve septic shock outcomes by enabling treatment of the correct patient with the correct vasopressor at the correct time. However, this approach requires validation in a large definitive multicenter trial. The data generated through the DARK-Sepsis study will prove crucial to the optimal design and patient enrichment of such a pivotal trial. TRIAL REGISTRATION: ClinicalTrials.gov NCT05824767. Registered on April 24, 2023.

The alternative renin-angiotensin system in critically ill patients: pathophysiology and therapeutic implications.

The renin-angiotensin system (RAS) plays a crucial role in regulating blood pressure and the cardio-renal system. The classical RAS, mainly mediated by angiotensin I, angiotensin-converting enzyme, and angiotensin II, has been reported to be altered in critically ill patients, such as those in vasodilatory shock. However, recent research has highlighted the role of some components of the counterregulatory axis of the classical RAS, termed the alternative RAS, such as angiotensin-converting Enzyme 2 (ACE2) and angiotensin-(1-7), or peptidases which can modulate the RAS like dipeptidyl-peptidase 3, in many critical situations. In cases of shock, dipeptidyl-peptidase 3, an enzyme involved in the degradation of angiotensin and opioid peptides, has been associated with acute kidney injury and mortality and preclinical studies have tested its neutralization. Angiotensin-(1-7) has been shown to prevent septic shock development and improve outcomes in experimental models of sepsis. In the context of experimental acute lung injury, ACE2 activity has demonstrated a protective role, and its inactivation has been associated with worsened lung function, leading to the use of active recombinant human ACE2, in preclinical and human studies. Angiotensin-(1-7) has been tested in experimental models of acute lung injury and in a recent randomized controlled trial for patients with COVID-19 related hypoxemia. Overall, the alternative RAS appears to have a role in the pathogenesis of disease in critically ill patients, and modulation of the alternative RAS may improve outcomes. Here, we review the available evidence regarding the methods of analysis of the RAS, pathophysiological disturbances of this system, and discuss how therapeutic manipulation may improve outcomes in the critically ill.

Dipeptidyl-peptidase 3 and IL-6: potential biomarkers for diagnostics in COVID-19 and association with pulmonary infiltrates.

Coronavirus SARS-CoV-2 spread worldwide, causing a respiratory disease known as COVID-19. The aim of the present study was to examine whether Dipeptidyl-peptidase 3 (DPP3) and the inflammatory biomarkers IL-6, CRP, and leucocytes are associated with COVID-19 and able to predict the severity of pulmonary infiltrates in COVID-19 patients versus non-COVID-19 patients. 114 COVID-19 patients and 35 patients with respiratory infections other than SARS-CoV-2 were included in our prospective observational study. Blood samples were collected at presentation to the emergency department. 102 COVID-19 patients and 28 non-COVID-19 patients received CT imaging (19 outpatients did not receive CT imaging). If CT imaging was available, artificial intelligence software (CT Pneumonia Analysis) was used to quantify pulmonary infiltrates. According to the median of infiltrate (14.45%), patients who obtained quantitative CT analysis were divided into two groups (> median: 55 COVID-19 and nine non-COVID-19, ≤ median: 47 COVID-19 and 19 non-COVID-19). DPP3 was significantly elevated in COVID-19 patients (median 20.85 ng/ml, 95% CI 18.34-24.40 ng/ml), as opposed to those without SARS-CoV-2 (median 13.80 ng/ml, 95% CI 11.30-17.65 ng/ml; p < 0.001, AUC = 0.72), opposite to IL-6, CRP (each p = n.s.) and leucocytes (p < 0.05, but lower levels in COVID-19 patients). Regarding binary logistic regression analysis, higher DPP3 concentrations (OR = 1.12, p < 0.001) and lower leucocytes counts (OR = 0.76, p < 0.001) were identified as significant and independent predictors of SARS-CoV-2 infection, as opposed to IL-6 and CRP (each p = n.s.). IL-6 was significantly increased in patients with infiltrate above the median compared to infiltrate below the median both in COVID-19 (p < 0.001, AUC = 0.78) and in non-COVID-19 (p < 0.05, AUC = 0.81). CRP, DPP3, and leucocytes were increased in COVID-19 patients with infiltrate above median (each p < 0.05, AUC: CRP 0.82, DPP3 0.70, leucocytes 0.67) compared to infiltrate below median, opposite to non-COVID-19 (each p = n.s.). Regarding multiple linear regression analysis in COVID-19, CRP, IL-6, and leucocytes (each p < 0.05) were associated with the degree of pulmonary infiltrates, as opposed to DPP3 (p = n.s.). DPP3 showed the potential to be a COVID-19-specific biomarker. IL-6 might serve as a prognostic marker to assess the extent of pulmonary infiltrates in respiratory patients.

Associations of dipeptidyl-peptidase 3 with short-term outcome in a mixed admission ICU-cohort.

PURPOSE: Biomarkers independently associated with outcome of intensive care unit (ICU) patients can improve risk assessment. The cytosolic protease dipeptidyl-peptidase 3 (DPP3) is released into the circulation upon cell necrosis. We aimed to investigate the prognostic properties of cDPP3 in a mixed-admission ICU cohort. MATERIALS AND METHODS: Prospective observational study in 650 adult ICU patients. cDPP3 concentrations were measured at ICU admission (day 1), and on days 2 and 3. RESULTS: cDPP3 concentrations on days 1 and 2, but not on day 3 were associated with 28-day mortality; HR 1.36 (95%CI 1.01-1.83, p = 0.043) and HR 1.49 (95%CI 1.16-1.93, p = 0.002) for days 1 and 2, respectively. cDPP3 was also associated with acute kidney injury (AKI), with OR's of 1.31 (95%CI 1.05-1.64, p = 0.016), 1.87 (95%CI 1.51-2.34, p < 0.001) and 1.49 (95%CI 1.16-1.92, p = 0.002) for measurements performed on days 1, 2, and 3, respectively. In multivariate analyses including SOFA or APACHE-II scores, cDPP3 assessed at day 2 of admission remained an independent predictor of mortality and all-stage AKI. CONCLUSIONS: In a mixed-ICU cohort, cDPP3 concentrations after start of initial treatment were independently associated with both mortality and development of AKI. Therefore, measurement of cDPP3 can improve risk-stratification provided by established disease severity scores.

The emerging role of dipeptidyl peptidase 3 in pathophysiology.

Dipeptidyl peptidase 3 (DPP3), a zinc-dependent aminopeptidase, is a highly conserved enzyme among higher animals. The enzyme cleaves dipeptides from the N-terminus of tetra- to decapeptides, thereby taking part in activation as well as degradation of signalling peptides critical in physiological and pathological processes such as blood pressure regulation, nociception, inflammation and cancer. Besides its catalytic activity, DPP3 moonlights as a regulator of the cellular oxidative stress response pathway, e.g., the Keap1-Nrf2 mediated antioxidative response. The enzyme is also recognized as a key modulator of the renin-angiotensin system. Recently, DPP3 has been attracting growing attention within the scientific community, which has significantly augmented our knowledge of its physiological relevance. Herein, we review recent advances in our understanding of the structure and catalytic activity of DPP3, with a focus on attributing its molecular architecture and catalytic mechanism to its wide-ranging biological functions. We further highlight recent intriguing reports that implicate a broader role for DPP3 as a valuable biomarker in cardiovascular and renal pathologies and furthermore discuss its potential as a promising drug target.

Effects of enrichment strategies on outcome of adrecizumab treatment in septic shock: Post-hoc analyses of the phase II adrenomedullin and outcome in septic shock 2 trial.

Purpose: Adrecizumab, a non-neutralizing antibody of adrenomedullin (ADM) was recently investigated regarding its potential to restore endothelial barrier function in septic shock patients with high plasma ADM levels. Circulating dipeptidyl peptidase 3 (cDPP3), a protease involved in the degradation of several cardiovascular mediators, represents another biological pathway strongly associated with outcome in septic shock, although unrelated to ADM. Therefore, the prognosis of patients with elevated cDPP3 may not be influenced by Adrecizumab. Also, time until initiation of treatment may influence efficacy. Objective: To evaluate effects of cDPP3-based enrichment on treatment efficacy of Adrecizumab. Materials and Methods: Post-hoc analysis of AdrenOSS-2, a phase-II, double-blind, randomized, placebo-controlled biomarker-guided trial of Adrecizumab. Results: Compared to the total study cohort [HR for 28-day mortality of 0.84 (95% CI 0.53;1.31), p = 0.439], therapeutic benefit of Adrecizumab tended to be more pronounced in the subgroup of 249 patients with low cDPP3 (<50 ng/mL); [HR of 0.61 (95% CI 0.34;1.08), p = 0.085]. Median duration to study drug infusion was 8.5 h. In the subgroup of 129 patients with cDPP3 <50 ng/mL and an early start of treatment (<8.5 h after septic shock diagnosis) HR for 28-day mortality vs. placebo was 0.49 (95% CI 0.21-1.18), p = 0.105. In multivariate interaction analyses corrected for baseline disease severity, both cDPP3, as well as the cDPP3 * treatment interaction term were associated with a reduced HR for 28-day mortality in the Adrecizumab treated group; p = 0.015 for cDPP3 in univariate analysis, p = 0.025 for the interaction term between cDPP3 and treatment group. In contrast, treatment timing was not significantly associated with 28-day mortality in multivariate interaction analyses. Discussion: In septic shock patients with high ADM levels, a further post-hoc enrichment strategy based on cDPP3 may indicate (with all the caveats to be considered for post-hoc subgroup analyses) that therapeutic efficacy is most pronounced in patients with lower cDPP3 levels.

DPP3: From biomarker to therapeutic target of cardiovascular diseases.

Cardiovascular disease is the leading cause of death globally among non-communicable diseases, which imposes a serious socioeconomic burden on patients and the healthcare system. Therefore, finding new strategies for preventing and treating cardiovascular diseases is of great significance in reducing the number of deaths and disabilities worldwide. Dipeptidyl peptidase 3 (DPP3) is the first zinc-dependent peptidase found among DPPs, mainly distributes within the cytoplasm. With the unique HEXXGH catalytic sequence, it is associated with the degradation of oligopeptides with 4 to 10 amino acids residues. Accumulating evidences have demonstrated that DPP3 plays a significant role in almost all cellular activities and pathophysiological mechanisms. Regarding the role of DPP3 in cardiovascular diseases, it is currently mainly used as a biomarker for poor prognosis in patients with cardiovascular diseases, suggesting that the level of DPP3 concentration in plasma is closely linked to the mortality of diseases such as cardiogenic shock and heart failure. Interestingly, it has been reported recently that DPP3 regulates blood pressure by interacting with the renin-angiotensin system. In addition, DPP3 also participates in the processes of pain signaling, inflammation, and oxidative stress. But the exact mechanism by which DPP3 affects cardiovascular function is not clear. Hence, this review summarizes the recent advances in the structure and catalytic activity of DPP3 and its extensive biological functions, especially its role as a therapeutic target in cardiovascular diseases. It will provide a theoretical basis for exploring the potential value of DPP3 as a therapeutic target for cardiovascular diseases.

Dipeptidyl peptidase-3 is associated with severity of liver disease and circulatory complications in patients with cirrhosis.

BACKGROUND: Patients with cirrhosis suffer from a complex multiorgan disturbance and their prognosis is influenced by the development of portal hypertension and systemic circulatory dysfunction. Although non-invasive techniques such as transient elastography aid in early detection, there is an unmet need for reliable markers of these clinically significant complications. METHODS: We conducted an exploratory single-center study investigating dipeptidyl peptidase-3 (DPP3) concentrations in various vascular beds in a cohort of 48 patients with cirrhosis and 16 healthy controls. Liver vein catheterisation with sampling from femoral artery and femoral, renal and hepatic veins as well as measurement of hepatic pressure and liver function via indocyanine green and galactose elimination tests were performed. RESULTS: DPP3 concentrations were higher in cirrhotic patients compared to controls (12.6 vs. 7.4 ng/mL, p = 0.006) and increased according to the severity of cirrhosis. DPP3 associated with MELD-Na score, Child class, indocyanine green clearance, increased DPP3 with the increased hepatic venous pressure gradient (p = 0.015) as well as increased heart rate and reduced systemic vascular resistance. DPP3 concentrations predicted the presence of clinically significant portal hypertension in cirrhotic patients (AUROC 0.78, 95% CI 0.65-0.9). CONCLUSION: DPP3 is a promising marker for portal hypertension and systemic hemodynamic changes in cirrhosis.

Circulating dipeptidyl peptidase 3 on intensive care unit admission is a predictor of organ dysfunction and mortality.

BACKGROUND: Our aim was to investigate the prognostic potential of circulating dipeptidyl peptidase 3 (cDPP3) to predict mortality and development of organ dysfunction in a mixed intensive care unit (ICU) population, and for this reason, we analysed prospectively collected admission blood samples from adult ICU patients at four Swedish hospitals. Blood samples were stored in a biobank for later batch analysis. The association of cDPP3 levels with 30-day mortality and Sequential Organ Failure Assessment (SOFA) scores on day two was investigated before and after adjustment for the simplified acute physiology score III (SAPS-3), using multivariable (ordinal) logistic regression. The predictive power of cDPP3 was assessed using the area under the receiver operating characteristic curve (AUROC). RESULTS: Of 1978 included consecutive patients in 1 year (2016), 632 fulfilled the sepsis 3-criteria, 190 were admitted after cardiac arrest, and 157 because of trauma. Admission cDPP3 was independently (of SAPS-3) associated with 30-day mortality with odds ratios of 1.45 (95% confidence interval (CI) 1.28-1.64) in the entire ICU population, 1.30 (95% CI 1.08-1.57) in the sepsis subgroup and 2.28 (95% CI 1.50-3.62) in cardiac arrest. For trauma, there was no clear association. Circulating DPP3 alone was a moderate predictor of 30-day mortality with AUROCs of 0.68, 0.62, and 0.72 in the entire group, the sepsis subgroup, and the cardiac arrest subgroup, respectively. By adding cDPP3 to SAPS-3, AUROC improved for the entire group, the sepsis subgroup, and the cardiac arrest subgroup (p = 0.023). CONCLUSION: Circulating DPP3 on admission is a SAPS-3 independent prognostic factor of day-two organ dysfunction and 30-day mortality in a mixed ICU population and needs further evaluation.

Plasma proenkephalin A 119-159 and dipeptidyl peptidase 3 on admission after cardiac arrest help predict long-term neurological outcome.

BACKGROUND: A large proportion of adult survivors of cardiac arrest have a poor neurological outcome. Guidelines recommend multimodal neuro-prognostication no earlier than 72-96 h after cardiac arrest. There is great interest in earlier prognostic markers, including very early markers at admission. The novel blood biomarkers proenkephalin A 119-159 (penKid), bioactive adrenomedullin (bio-ADM) and circulating dipeptidyl peptidase 3 (cDPP3) have not been previously investigated for the early prognosis of cardiac arrest survivors. METHODS: This multicentre observational study included adult survivors of cardiac arrest admitted to intensive care at four Swedish intensive care units (ICUs) during 2016. Blood samples were collected at ICU admission and batch analysed. The association between admission plasma penKid, bio-ADM and cDPP3 and poor long-term neurological outcome, according to the Cerebral Performance Category (CPC) scale, was assessed by binary logistic regression. Their prognostic performance was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS: A total of 190 patients were included, of which 136 patients had suffered out-of-hospital and 54 patients in-hospital cardiac arrest. Poor long-term neurological outcome was associated with elevated admission plasma concentrations of penKid and cDPP3, but not with bio-ADM. The association for penKid, but not for cDPP3, remained after adjusting for clinical cardiac arrest variables with prognostic value (time to return of spontaneous circulation (ROSC), initial rhythm, admission Glasgow coma scale (GCS) motor score and absence of pupillary reflexes). The prognostic performance of above mentioned clinical cardiac arrest variables alone was very good with an AUC of 0.90 (95% confidence interval, CI, 0.86-0.95), but improved further with the addition of penKid resulting in an AUC of 0.93 (95% CI 0.89-0.97, p < 0.026). Plasma penKid and cDPP3 alone provided moderate long-term prognostic information with AUCs of 0.70 and 0.71, respectively. CONCLUSION: After cardiac arrest, admission plasma levels of penKid and cDPP3, but not bio-ADM, predicted long-term neurological outcome. When added to clinical cardiac arrest variables, penKid further improved prognostic performance.

Dipeptidyl peptidase 3, a marker of the antagonist pathway of the renin-angiotensin-aldosterone system in patients with heart failure.

AIMS: Recently, dipeptidyl peptidase 3 (DPP3) has been discovered as the peptidase responsible for cleavage of angiotensin (1-7) [Ang (1-7)]. Ang (1-7) is part of the angiotensin-converting enzyme-Ang (1-7)-Mas pathway which is considered to antagonize the renin-angiotensin-aldosterone system (RAAS). Since DPP3 inhibits the counteracting pathway of the RAAS, we hypothesize that DPP3 might be deleterious in the setting of heart failure. However, no data are available on DPP3 in chronic heart failure. We therefore investigated the clinical characteristics and outcome related to elevated DPP3 concentrations in patients with worsening heart failure. METHODS AND RESULTS: Dipeptidyl peptidase 3 was measured in 2156 serum samples of patients with worsening heart failure using luminometric immunoassay (DPP3-LIA) by 4TEEN4 Pharmaceuticals GmbH, Hennigsdorf, Germany. Predictors of DPP3 levels were selected using multiple linear regression with stepwise backward selection. Median DPP3 concentration was 11.45 ng/mL with a range from 2.8 to 84.9 ng/mL. Patients with higher DPP3 concentrations had higher renin [78.3 (interquartile range, IQR 26.3-227.7) vs. 120.7 IU/mL (IQR 34.74-338.9), P < 0.001, for Q1-3 vs. Q4] and aldosterone [88 (IQR 44-179) vs. 116 IU/mL (IQR 46-241), P < 0.001, for Q1-3 vs. Q4] concentrations. The strongest independent predictors for higher concentration of DPP3 were log-alanine aminotransferase, log-total bilirubin, the absence of diabetes, higher osteopontin, fibroblast growth factor-23 and N-terminal pro-B-type natriuretic peptide concentrations (all P < 0.001). In univariable survival analysis, DPP3 was associated with mortality and the combined endpoint of death or heart failure hospitalization (P < 0.001 for both). After adjustment for confounders, this association was no longer significant. CONCLUSIONS: In patients with worsening heart failure, DPP3 is a marker of more severe disease with higher RAAS activity. It may be deleterious in heart failure by counteracting the Mas receptor pathway. Procizumab, a specific antibody against DPP3, might be a potential future treatment option for patients with heart failure.

In-hospital mortality and organ failure after open and endovascular thoraco-abdominal aortic surgery can be predicted by increased levels of circulating dipeptidyl peptidase 3.

OBJECTIVES: Endovascular and open thoraco-abdominal aortic aneurysm (TAAA) repair is associated with specific complications. Circulating dipeptidyl peptidase 3 (cDPP3) is a novel biomarker that shows a strong association with organ failure which has not been assessed in surgical settings. Therefore, the objective of this study was to assess the prognostic capabilities of cDPP3 for predicting patient survival and organ failure following open and endovascular TAAA repair. METHODS: Thirty-three patients undergoing TAAA repair were assessed in this prospective observational single-centre study. cDPP3 levels were serially measured perioperatively until 72 h after admission to the intensive care unit (ICU). In-hospital mortality and any organ failure were the clinical end points. RESULTS: Postoperative organ failure was detected in 17 patients (51.5%), and 6 patients died after surgery (18.2%). At 12 h after admission to the ICU, cDPP3 levels were significantly increased in patients who died or developed organ failure (P < 0.001). cDPP3 levels after surgery demonstrated a remarkable predictive accuracy for in-hospital mortality [12 h area under the receiver operating characteristic curve (AUC): 0.907 (P < 0.001), 24 h AUC: 0.815 (P = 0.016), 48 h AUC: 0.914 (P = 0.003)] and the development of organ failure [12 h AUC: 0.882 (P < 0.001), 24 h AUC: 0.850 (P < 0.001), 48 h AUC: 0.846 (P < 0.001)]. Additionally, a significant correlation between cDPP3, the sequential organ failure assessment score and procalcitonin, C-reactive protein and interleukin-6 levels (P < 0.001, P < 0.001, P = 0.011, P = 0.007, respectively) based on all available measurements and time points was observed. CONCLUSIONS: The present findings highlight the role of cDPP3 as an early, highly specific postoperative biomarker for prediction of in-hospital mortality and organ failure after TAAA repair.

Dipeptidyl peptidase 3 modulates the renin-angiotensin system in mice.

Dipeptidyl peptidase 3 (DPP3) is a zinc-dependent hydrolase involved in degrading oligopeptides with 4-12 amino acid residues. It has been associated with several pathophysiological processes, including blood pressure regulation, pain signaling, and cancer cell defense against oxidative stress. However, the physiological substrates and the cellular pathways that are potentially targeted by DPP3 to mediate these effects remain unknown. Here, we show that global DPP3 deficiency in mice (DPP3-/-) affects the renin-angiotensin system (RAS). LC-MS-based profiling of circulating angiotensin peptides revealed elevated levels of angiotensin II, III, IV, and 1-5 in DPP3-/- mice, whereas blood pressure, renin activity, and aldosterone levels remained unchanged. Activity assays using the purified enzyme confirmed that angiotensin peptides are substrates for DPP3. Aberrant angiotensin signaling was associated with substantially higher water intake and increased renal reactive oxygen species formation in the kidneys of DPP3-/- mice. The metabolic changes and altered angiotensin levels observed in male DPP3-/- mice were either absent or attenuated in female DPP3-/- mice, indicating sex-specific differences. Taken together, our observations suggest that DPP3 regulates the RAS pathway and water homeostasis by degrading circulating angiotensin peptides.