Andrew J. Lautz

Objective: Sepsis-associated acute kidney injury (SAKI) is a heterogeneous condition that lacks disease-modifying treatments, and precision medicine approaches are needed. We previously derived two reproducible pediatric SAKI subphenotypes (pSAKI-1 and pSAKI-2) from readily available clinical data. We aimed to externally validate the prognostic relevance of these subphenotypes, evaluate their molecular signatures, and assess for heterogeneity of treatment effect (HTE) across subphenotypes with sepsis therapies. Design: Secondary analysis of an ongoing multicenter, prospective, observational study of children. Setting: Ten PICUs in the United States from January 2002 to February 2025. Patients: Patients 1 week to 18 years old with early (day 1–2) SAKI. Interventions: None. Measurements and Main Results: Among 871 patients, 665 (76%) were assigned pSAKI-1 and 206 (24%) to pSAKI-2. On day 1–2, the pSAKI-2 cohort had greater severity of illness, including higher acute kidney injury stage and vasoactive burden, lower platelet counts, and higher lactate values and International Normalized Ratios. These pSAKI-2 patients also had uniformly worse outcomes, including independently higher odds of day 7 severe acute kidney injury (adjusted odds ratio [aOR] 3.2; 95% CI, 2.1–4.7; p < 0.001), death (aOR 2.7; 95% CI, 1.6–4.4; p < 0.001), and fewer PICU-free and vasoactive-free days ( p < 0.001). The biomarker signature of pSAKI-2 was characterized by greater inflammation, endothelial dysfunction, and hyperreninemia. On propensity score matched (PSM) analysis, pSAKI-1 patients who received corticosteroids had more day 7 severe acute kidney injury (28% vs. 19%, p = 0.023), 2 fewer PICU-free days ( p = 0.04) and greater mortality (10% vs. 3.7%, p = 0.008); no differences were seen in pSAKI-2 patients. Although no HTE was identified on PSM analysis for vasopressin, inverse probability treatment weighting analysis demonstrated a significant interaction between subphenotype-, vasopressin- and vasoactive-free days ( p = 0.003). Conclusions: We externally validated the prognostic relevance of two pSAKI subphenotypes derived from readily available data. These subphenotypes have unique biomarker signatures and differential responses to treatment, representing a potential mechanism for bedside enrichment.

Background: Sepsis-associated myocardial dysfunction (SAMD) is common in children with septic shock, is independently associated with mortality, and has no disease-modifying treatments. Differences in murine cardiomyocyte biology and repeated failures to translate discoveries into novel therapies for septic shock underscore a key translational need for human-relevant disease modeling. We sought to investigate human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) exposed to mortality risk-stratified septic serum as a model of SAMD. Methods: Serum from children with septic shock (n=120) was stratified by Pediatric Sepsis Biomarker Risk Model (PERSEVERE) II mortality probability as low, intermediate, or high risk. We conducted aptamer-based proteomic analysis of septic serum to determine differentially expressed proteins in children with high compared to low mortality risk. We treated iPSC-CMs with risk-stratified septic serum and defined contractile and mitochondrial functional and transcriptomic responses. Results: We found 612 differentially expressed proteins in children with high mortality probability, most prominently interleukins (IL)-6 and -8. High-risk septic serum reversibly depressed iPSC-CM contractility as measured by percent shortening, while low-risk septic serum had no impact. Further, high-risk septic serum depressed basal mitochondrial respiration, maximum uncoupled respiration, and coupled oxidative phosphorylation in iPSC-CMs relative to low-risk serum. We identified distinct patterns of gene expression due to risk-stratified serum with 5,293 differentially expressed genes, including upregulation of acute phase reactants and apolipoproteins and downregulation of chemokines, as well as transcriptional changes reflective of chronic IL-6 and IL-8 signaling. Conclusions: Septic serum from children with high mortality risk exhibited distinct proteomic signatures, notably enriched for IL-6 and IL-8. Human iPSC-CMs differentially responded to risk-stratified septic serum, recapitulating phenotypic features of SAMD including reversible contractility depression and mitochondrial dysfunction with high-risk septic serum. These findings establish mortality risk-stratified septic serum exposure of iPSC-CMs as a human-relevant translational platform to interrogate mechanisms of myocardial dysfunction in septic shock.

Background: Pediatric sepsis is a leading cause of global mortality, particularly among children, with limited therapeutic options beyond antibiotics and organ support. The Pediatric Sepsis Biomarker Risk Model (PERSEVERE-II) stratifies mortality risk in pediatric septic shock, yet the molecular mechanisms underlying high mortality risk remain incompletely understood. Methods: We analyzed whole blood transcriptomes collected from 81 children with septic shock on day 1 of meeting study criteria. Patients were stratified into high- and low-mortality risk groups according to the PERSEVERE-II biomarker risk model. Using weighted gene co-expression network analysis (WGCNA) and differential gene expression analyses, we identified molecular pathways and transcription factors (TFs) associated with mortality risk. Cell type differences were inferred using CIBERSORTx and using a reference single-cell dataset inclusive of neutrophils and their subsets. Findings: We identified distinct molecular profiles with high-risk patients displaying significant overexpression of genes related to neutrophil degranulation and innate immunity, alongside suppressed adaptive immune responses. The predominance of developing neutrophils underscored a major role of emergency granulopoiesis. Key TFs identified, including LTF , FOXM1 , KLF1 , and CEBPB , were linked to high-risk gene expression signatures. Our findings indicate a pathological shift toward a dysregulated neutrophil-driven hyperinflammation and adaptive immune suppressive state, which together are associated with adverse outcomes. Interpretation: Our results suggest that neutrophil dysregulation underpins the high mortality risk conferred by the PERSEVERE-II model. The identified transcriptional regulators may provide potential targets to mitigate neutrophil dysregulation and improve outcomes among high-risk patients.

OBJECTIVES: Sepsis-associated myocardial dysfunction is common in pediatric septic shock and negatively impacts outcomes. Early estimation of sepsis-associated myocardial dysfunction risk has the potential to inform clinical care and improve clinical trial design. The Pediatric Sepsis Biomarker Risk Model II is validated as a biomarker-based enrichment algorithm to discriminate children with septic shock with high baseline mortality probability. The objectives were to determine if Pediatric Sepsis Biomarker Risk Model biomarkers are associated with risk for sepsis-associated myocardial dysfunction in pediatric septic shock and to develop a biomarker-based model to reliably estimate sepsis-associated myocardial dysfunction risk. DESIGN: Secondary analysis of prospective cohort study. SETTING: Single-center, quaternary-care PICU. PATIENTS: Children less than 18 years old admitted to the PICU from 2003 to 2018 who had Pediatric Sepsis Biomarker Risk Model biomarkers measured for determination of Pediatric Sepsis Biomarker Risk Model II mortality probability and an echocardiogram performed within 48 hours of septic shock identification. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pediatric Sepsis Biomarker Risk Model II mortality probability was calculated from serum biomarker concentrations and admission platelet count. Echocardiograms were reread by a single cardiologist blinded to Pediatric Sepsis Biomarker Risk Model II data, and sepsis-associated myocardial dysfunction was defined as left ventricular ejection fraction less than 45% for primary analyses. Multivariable logistic regression analyzed the association of Pediatric Sepsis Biomarker Risk Model II mortality probability with sepsis-associated myocardial dysfunction. Classification and regression tree methodology was employed to derive a Pediatric Sepsis Biomarker Risk Model biomarker-based model for sepsis-associated myocardial dysfunction. Thirty-two of 181 children with septic shock demonstrated sepsis-associated myocardial dysfunction. Pediatric Sepsis Biomarker Risk Model II mortality probability was independently associated with sepsis-associated myocardial dysfunction (odds ratio, 1.45; 95% CI, 1.17–1.81; p = 0.001). Modeling with Pediatric Sepsis Biomarker Risk Model biomarkers estimated sepsis-associated myocardial dysfunction risk with an area under the receiver operating characteristic curve of 0.90 (95% CI, 0.85–0.95). Upon 10-fold cross-validation, the derived model had a summary area under the receiver operating characteristic curve of 0.74. Model characteristics were similar when sepsis-associated myocardial dysfunction was defined by both low left ventricular ejection fraction and abnormal global longitudinal strain. CONCLUSIONS: A newly derived Pediatric Sepsis Biomarker Risk Model biomarker-based model reliably estimates risk of sepsis-associated myocardial dysfunction in pediatric septic shock, but independent prospective validation is needed.

Objectives: Circulatory dysfunction has been associated with mortality in children with septic shock. However, the mortality risk attributable to myocardial dysfunction per se has not been established, and the association between myocardial dysfunction and mortality is confounded by illness severity. The objective was to determine if sepsis-associated myocardial dysfunction defined by low left ventricular ejection fraction or global longitudinal strain is associated with mortality in pediatric septic shock after adjusting for baseline mortality probability. Design: Retrospective, observational study. Setting: Single-center, quaternary-care PICU. Patients: Children less than 18 years old admitted to the PICU from 2003 to 2018 who had an echocardiogram performed within 48 hours of septic shock identification and Pediatric Sepsis Biomarker Risk Model II data available. Interventions: None. Measurements and Main Results: All echocardiograms were reread by a cardiologist blinded to patient data for left ventricular ejection fraction and global longitudinal strain. Low left ventricular ejection fraction was defined as less than 45%, and low global longitudinal strain was defined as greater than z score of –2 for body surface area. Multivariable logistic regression separately analyzed the associations of low left ventricular ejection fraction and low global longitudinal strain with mortality, adjusting for Pediatric Sepsis Biomarker Risk Model II mortality risk. A post hoc logistic regression analyzed the association of left ventricular ejection fraction as a continuous variable with mortality, where linearity was maintained for left ventricular ejection fraction less than 65%. Eighteen percent of 181 children had low left ventricular ejection fraction. After adjusting for baseline mortality risk, low left ventricular ejection fraction remained independently associated with mortality (odds ratio, 4.4 [1.0–19.8]; p = 0.0497). Likewise, left ventricular ejection fraction was associated with mortality (odds ratio, 0.96 [0.93–0.99]; p = 0.037) on multivariable analysis for left ventricular ejection fraction less than 65%. Thirty-six percent of 169 children had low global longitudinal strain, and low global longitudinal strain was also independently associated with mortality (odds ratio, 4.6 [1.2–18.0]; p = 0.027). Conclusions: Sepsis-associated myocardial dysfunction, whether defined by low left ventricular ejection fraction or low global longitudinal strain, is an independent risk factor for mortality in pediatric septic shock after accounting for the confounding effects of septic shock severity.

Myocardial dysfunction is common in septic shock and post-cardiac arrest but manifests differently in pediatric and adult patients. By conventional echocardiographic parameters, biventricular systolic dysfunction is more prevalent in children with septic shock, though strain imaging reveals that myocardial injury may be more common in adults than previously thought. In contrast, diastolic dysfunction in general and post-arrest myocardial systolic dysfunction appear to be more widespread in the adult population. A growing body of evidence suggests that mitochondrial dysfunction mediates myocardial depression in critical illness; alterations in mitochondrial electron transport system function, bioenergetic production, oxidative and nitrosative stress, uncoupling, mitochondrial permeability transition, fusion, fission, biogenesis, and autophagy all may play key pathophysiologic roles. In this review we summarize the epidemiologic and clinical phenotypes of myocardial dysfunction in septic shock and post-cardiac arrest and the multifaceted manifestations of mitochondrial injury in these disease processes. Since neonatal and pediatric-specific data for mitochondrial dysfunction remain sparse, conclusive age-dependent differences are not clear; instead, we highlight what evidence exists and identify gaps in knowledge to guide future research. Finally, since focal ischemic injury (with or without reperfusion) leading to myocardial infarction is predominantly an atherosclerotic disease of the elderly, this review focuses specifically on septic shock and global ischemia-reperfusion injury occurring after resuscitation from cardiac arrest.

Objectives: Less than half of the thousands of children who suffer in-hospital cardiac arrests annually survive, and neurologic injury is common among survivors. Hemodynamic-directed cardiopulmonary resuscitation improves short-term survival, but its impact on longer term survival and mitochondrial respiration—a potential neurotherapeutic target—remains unknown. The primary objectives of this study were to compare rates of 24-hour survival with favorable neurologic outcome after cardiac arrest treated with hemodynamic-directed cardiopulmonary resuscitation versus standard depth-guided cardiopulmonary resuscitation and to compare brain and heart mitochondrial respiration between groups 24 hours after resuscitation. Design: Randomized preclinical large animal trial. Setting: A large animal resuscitation laboratory at a large academic children’s hospital. Subjects: Twenty-eight 4-week-old female piglets (8–11 kg). Interventions: Twenty-two swine underwent 7 minutes of asphyxia followed by ventricular fibrillation and randomized treatment with either hemodynamic-directed cardiopulmonary resuscitation (n = 10; compression depth titrated to aortic systolic pressure of 90 mm Hg, vasopressors titrated to coronary perfusion pressure ≥ 20 mm Hg) or depth-guided cardiopulmonary resuscitation (n = 12; depth 1/3 chest diameter, epinephrine every 4 min). Six animals (sham group) underwent anesthesia and instrumentation without cardiac arrest. The primary outcomes were favorable neurologic outcome (swine Cerebral Performance Category ≤ 2) and mitochondrial maximal oxidative phosphorylation utilizing substrate for complex I and complex II (OXPHOS_CI+CII) in the cerebral cortex and hippocampus. Measurements and Main Results: Favorable neurologic outcome was more likely with hemodynamic-directed cardiopulmonary resuscitation (7/10) than depth-guided cardiopulmonary resuscitation (1/12; p = 0.006). Hemodynamic-directed cardiopulmonary resuscitation resulted in higher intra-arrest coronary perfusion pressure, aortic pressures, and brain tissue oxygenation. Hemodynamic-directed cardiopulmonary resuscitation resulted in higher OXPHOS_CI+CII (pmol oxygen/s × mg/citrate synthase) in the cortex (6.00 ± 0.28 vs 3.88 ± 0.43; p < 0.05) and hippocampus (6.26 ± 0.67 vs 3.55 ± 0.65; p < 0.05) and higher complex I respiration (pmol oxygen/s × mg) in the right (20.62 ± 1.06 vs 15.88 ± 0.81; p < 0.05) and left ventricles (20.14 ± 1.40 vs 14.17 ± 1.53; p < 0.05). Conclusions: In a model of asphyxia-associated pediatric cardiac arrest, hemodynamic-directed cardiopulmonary resuscitation increases rates of 24-hour survival with favorable neurologic outcome, intra-arrest hemodynamics, and cerebral and myocardial mitochondrial respiration.