Daily ReportSep 22, 2026
Sepsis, September 22 edition
We read 39 papers and selected 3.
Summary
Today's strongest sepsis papers advance mechanistic understanding, precision dosing, and pediatric risk stratification. The leading studies connect cell-free hemoglobin to endothelial glycocalyx injury, quantify how immune suppression alters antibiotic PK/PD targets, and externally validate the Phoenix sepsis score across clinically important pediatric subgroups.
Research Themes
- Endothelial glycocalyx injury and therapeutic mechanisms
- Immune-informed antibiotic PK/PD optimization
- Pediatric sepsis severity assessment and external validation
Selected Articles
1. Cell-free hemoglobin upregulates pulmonary endothelial heparanase expression to drive glycocalyx destruction and inflammation in sepsis.
Using human sepsis samples, a murine peritonitis model, endothelial heparanase deletion, and human pulmonary endothelial cells, the study identified a CFH–heparanase pathway driving endothelial glycocalyx degradation and inflammation. Oxidized CFH increased heparanase expression and activation, whereas endothelial heparanase deletion or acetaminophen attenuation reduced glycocalyx injury and inflammatory effects.
Impact: This study defines a mechanistic link between hemolysis-related cell-free hemoglobin and endothelial barrier failure in sepsis, integrating patient associations with genetic and cellular validation. The CFH–heparanase axis provides a biologically coherent therapeutic target for preserving the endothelial glycocalyx.
Clinical Implications: The findings support investigation of therapies that reduce oxidized cell-free hemoglobin or inhibit endothelial heparanase to prevent microvascular dysfunction and organ injury. Clinical translation will require validation of circulating CFH and heparanase as treatment-selection or pharmacodynamic biomarkers.
Key Findings
- In human sepsis, higher circulating cell-free hemoglobin was associated with increased heparanase and heparan sulfate levels and adverse clinical outcomes.
- Cell-free hemoglobin increased pulmonary endothelial heparanase expression, glycocalyx degradation, and systemic and pulmonary inflammation in cellular and murine models.
- Endothelial heparanase deletion abrogated the deleterious effects of cell-free hemoglobin, while acetaminophen attenuated them.
Methodological Strengths
- Convergent validation across human sepsis samples, an in vivo murine model, genetically modified animals, and human endothelial cells.
- Mechanistic interrogation of causality through endothelial heparanase deletion and pharmacological attenuation.
Limitations
- The clinical component is primarily associative and does not establish whether the CFH–heparanase pathway is a modifiable determinant of patient outcomes.
- The therapeutic attenuation data with acetaminophen require validation in clinically relevant dosing and treatment-after-sepsis-onset models.
Future Directions: Future work should evaluate CFH oxidation state and heparanase activity as longitudinal biomarkers, test selective heparanase or hemoglobin-targeted interventions after sepsis onset, and determine whether specific sepsis phenotypes benefit from glycocalyx-directed therapy.
Both elevated plasma cell-free hemoglobin (CFH) and heparanase-driven endothelial glycocalyx shedding are contributors to microvascular dysfunction and organ injury in sepsis. However, the mechanisms governing heparanase activation, and the potential role of CFH in this process, are not understood. Utilizing patient samples, mice with cecal slurry-induced (CS) peritonitis and elevated CFH, and human lung microvascular endothelial cells (HLMVECs), we tested the hypothesis that CFH upregulates heparanase production to drive endothelial glycocalyx degradation.
2. A mechanism-based model of immune status effects on antibiotic PK/PD targets in bacteremia.
The investigators developed a mechanism-based host–pathogen–drug model incorporating neutrophil and monocyte phagocytosis and calibrated it using in vitro and in vivo data. In silico bacteremia simulations showed that combined severe neutropenia and monocytopenia required up to a 2.2-fold higher AUC/MIC target for concentration-dependent antibiotics and a 58% higher T>MIC target for time-dependent antibiotics.
Impact: This work challenges the conventional assumption that antibiotic PK/PD targets are largely host-independent. It offers a quantitative framework for immune-informed dosing in immunocompromised patients, a population at high risk for treatment failure.
Clinical Implications: The model supports individualized antibiotic exposure targets in patients with neutropenia, monocytopenia, or combined immune suppression. Prospective pharmacokinetic and clinical outcome studies are needed before implementing immune-adjusted dosing in routine practice.
Key Findings
- A host–pathogen interaction model was integrated with pharmacodynamic drug models for four antibiotic modalities.
- Calibration to immune-competent rodent infection data required a 77% reduction in maximum phagocytosis rates compared with in vitro estimates for both neutrophils and monocytes.
- Combined severe neutropenia and monocytopenia increased the required AUC/MIC target by up to 2.2-fold and the T>MIC target by up to 58%.
Methodological Strengths
- Mechanism-based mathematical modeling explicitly incorporated immune-cell concentrations, phagocytosis, digestion, and finite ingestion capacity.
- Parameterization and calibration used data from multiple in vitro host–pathogen studies and prior in vivo infection models.
Limitations
- The principal dosing conclusions are based on in silico simulations rather than prospective human pharmacokinetic or outcome data.
- The model simplifies the heterogeneous immune, pathogen, infection-site, and antibiotic characteristics encountered in clinical bacteremia.
Future Directions: Future studies should prospectively measure antibiotic exposure and immune-cell function in bacteremic patients, validate immune-adjusted PK/PD targets against microbiological and clinical outcomes, and evaluate therapeutic drug monitoring strategies in immunocompromised populations.
A key determinant of antibiotic dose selection is the pharmacokinetic/pharmacodynamic (PK/PD) target, typically determined using dose fractionation studies in preclinical infection models. However, such studies often do not consider the host immune response, despite its important role in bacterial infection. We therefore aimed to systematically characterize the potential contributions of the innate immune response on antibiotic PK/PD targets using a novel mathematical mechanism-based model, incorporating interactions between neutrophils, monocytes and bacterial pathogens.
3. Discrimination performance of the Phoenix sepsis score versus pediatric sequential organ failure assessment for predicting in-hospital mortality in critically ill children: a multicenter external validation study.
This multicenter external validation study evaluated 2,374 children with suspected infection across 13 intensive care units and compared Phoenix sepsis score with pediatric SOFA. Phoenix demonstrated superior overall mortality discrimination and better performance in the hematology subgroup, but there was no statistically significant difference in neonates, and both tools had limited positive predictive value at the ≥2-point threshold.
Impact: The study provides independent, clinically relevant validation of a contemporary pediatric sepsis severity tool in a large multicenter cohort. Its subgroup findings appropriately temper broad claims of superiority and are important for implementation in neonatal and hematology populations.
Clinical Implications: Phoenix may be preferable to pediatric SOFA for mortality risk discrimination in general critically ill children and some hematology populations. However, score-based decisions should not be used alone for diagnosis or treatment escalation, particularly in neonates where positive predictive value was low.
Key Findings
- Among 2,374 children with suspected infection, Phoenix had higher adjusted AUROC than pediatric SOFA for in-hospital mortality overall: 0.840 versus 0.817.
- Phoenix also outperformed pediatric SOFA in the hematology subgroup, with adjusted AUROC values of 0.718 versus 0.682.
- In neonates, the difference was not statistically significant; at the ≥2-point threshold, both scores had high sensitivity but low positive predictive value.
Methodological Strengths
- Large multicenter external validation cohort including predefined neonatal and hematology subgroups.
- Direct comparison using adjusted AUROC and clinically relevant sensitivity and positive predictive value analyses.
Limitations
- The retrospective design may introduce selection, measurement, and treatment-related biases.
- The study evaluates mortality discrimination rather than whether score use improves recognition, treatment timing, or patient outcomes.
Future Directions: Prospective implementation studies should assess whether Phoenix-guided pathways improve early treatment, resource allocation, and outcomes, with recalibration or subgroup-specific thresholds for neonates and children with hematologic disease.
BACKGROUND: This study compared the prognostic accuracy of the Phoenix sepsis score (PSS) and the pediatric sequential organ failure assessment (pSOFA) score for predicting in-hospital mortality in critically ill children with suspected infection, with a focus on neonatal and hematology sub-cohorts. METHODS: This retrospective, multicenter cohort study analyzed data from 2374 children (< 18 years) with suspected infections admitted to 13 intensive care units (ICUs) between 2023 and 2025. Two predefined sub-cohorts were examined: the neonatal sub-cohort (≤ 28 days; n = 576) and the hematology sub-cohort (n = 494).