Quarterly ReportJan 1 – Mar 31, 2025
Sepsis, Q1 2025 edition
We read 272 papers and selected 10.
Summary
Sepsis research in 2025-Q1 moved decisively toward mechanism-based and phenotype-specific science rather than nonspecific immunomodulation. Studies identified interconnected host–microbiome–pathogen mechanisms, including AhR–enterobactin signaling, TLR4-driven luminal redox disruption, tissue macrophage barriers, and extracellular-vesicle-mediated endothelial ferroptosis. Translational work also expanded the therapeutic pipeline through pathogen-derived carbon dots, fluoxetine-mediated immunometabolic protection, and AI-supported vasopressor optimization, although most interventions remain preclinical or observational. Rapid diagnostics and longitudinal prediction advanced through metagenomics, molecular pathogen detection, time-series deep learning, and reinforcement-learning treatment policies. The quarter additionally broadened the scientific conception of sepsis outcomes to include muscle wasting, immune-phase biology, secondary infection, and prevention of infection progression. Overall, the strongest contributions were those that introduced causal mechanisms or transferable methods with potential to guide future experimental and clinical research, rather than papers whose primary value was guideline or policy influence.
Selected Articles
1. Enterobactin inhibits microbiota-dependent activation of AhR to promote bacterial sepsis in mice.
This mechanistic mouse study showed that microbiota-derived tryptophan metabolites activate macrophage AhR, improve bacterial clearance, and increase survival. The pathogen-derived siderophore enterobactin inhibited AhR activation and worsened sepsis, whereas tryptophan supplementation restored survival.
Impact: The paper established a causal microbiota–host–pathogen axis linking microbial metabolites, virulence, macrophage function, and survival. It created several testable therapeutic concepts, including AhR agonism, nutritional modulation, and siderophore neutralization.
Clinical Implications: The findings support human studies of AhR-directed therapy, microbiome-preserving antimicrobial strategies, and metabolite-based interventions. Human pharmacology, safety, and microbiome heterogeneity remain major barriers.
Key Findings
- Microbiota-derived indoles activated macrophage AhR and improved survival in murine sepsis.
- Macrophage-specific AhR loss impaired bacterial clearance and reduced survival.
- Enterobactin inhibited AhR activation, while tryptophan supplementation restored survival.
2. Sublethal systemic LPS in mice enables gut-luminal pathogens to bloom through oxygen species-mediated microbiota inhibition.
In mice, physiologic-range systemic LPS caused rapid expansion of facultative pathogens without overt enteropathy. TLR4-driven increases in luminal reactive oxygen species inhibited normal fermentation and favored oxidative-respiration growth by Klebsiella, E. coli, Enterococcus, and Salmonella.
Impact: The study provided a compelling host-side mechanism for microbiome collapse and secondary pathogen blooms during systemic inflammation. It identified TLR4 signaling and luminal redox regulation as preventive targets.
Clinical Implications: The findings support investigation of microbiome-preserving, TLR4-modulating, or luminal redox-directed strategies. Human confirmation is required before therapeutic translation.
Key Findings
- Systemic LPS caused 100- to 10,000-fold expansion of several facultative gut pathogens within 24 hours.
- The response depended on TLR4 signaling.
- Increased luminal reactive oxygen species inhibited fermentation and favored pathogen growth.
3. Suppression of Sepsis Cytokine Storm by Escherichia Coli Cell Wall-Derived Carbon Dots.
This translational study developed E. coli cell-wall-derived carbon dots that bind LBP/LPS, promote TLR4 degradation, suppress NF-kB and STING signaling, and reduce oxidative stress. The material improved survival and organ function in septic mice and cynomolgus monkeys, with concordant anti-inflammatory effects in human PBMCs.
Impact: It introduced an unconventional pathogen-derived nanomaterial as a multi-pathway host-directed immunomodulator. Multi-species validation and concordant human-cell findings increased its translational value.
Clinical Implications: The platform may eventually support adjunctive treatment of hyperinflammatory sepsis, but pharmacokinetics, immunogenicity, biodistribution, manufacturing consistency, and preservation of antimicrobial defense require rigorous study.
Key Findings
- Carbon dots reduced cytokine production, organ injury, and mortality in septic mice.
- The mechanism involved LBP–LPS binding, TLR4 degradation, NF-kB inhibition, and STING attenuation.
- Anti-inflammatory effects were reproduced in cynomolgus monkeys and human PBMCs.
4. Optimal Vasopressin Initiation in Septic Shock: The OVISS Reinforcement Learning Study.
This multicenter study used electronic health-record data and reinforcement learning to derive and externally validate a treatment policy favoring earlier vasopressin initiation at lower norepinephrine doses. Across validation data from 227 hospitals, policy-concordant treatment was associated with lower in-hospital mortality. The work provides a transparent example of using dynamic clinical data to generate treatment hypotheses.
Impact: It introduced an externally evaluated, clinically interpretable computational approach to dynamic vasopressor sequencing. Its importance is methodological and hypothesis-generating, although the observational design does not establish causal treatment benefit.
Clinical Implications: The policy supports prospective pragmatic trials of earlier vasopressin initiation and cautious development of electronic decision support. It should not yet be used as proof that earlier vasopressin improves survival.
Key Findings
- The reinforcement-learning policy recommended vasopressin in 87% of cases compared with 31% under usual care.
- Policy-concordant treatment began vasopressin earlier and at lower norepinephrine doses.
- Concordant treatment was associated with lower mortality across external validation datasets.
5. Extracellular vesicle-packaged GBP2 from macrophages aggravates sepsis-induced acute lung injury by promoting ferroptosis in pulmonary vascular endothelial cells.
This study identified a macrophage extracellular-vesicle GBP2–OTUD5–GPX4 pathway that promotes endothelial ferroptosis and vascular barrier disruption in sepsis-associated lung injury. Patient EV samples, cell experiments, sepsis models, endothelial-specific Gpx4 knockout models, and the candidate compound Plantainoside D supported the mechanism.
Impact: It connected extracellular-vesicle communication to endothelial ferroptosis using complementary mechanistic models and identified both a circulating biomarker candidate and a druggable molecular interaction.
Clinical Implications: EV-associated GBP2 may support endothelial-injury stratification, while GBP2, OTUD5, GPX4 ubiquitination, and Plantainoside D define a translational therapy pipeline. Pharmacokinetics, toxicology, and prospective biomarker validation are required.
Key Findings
- Macrophage-derived extracellular vesicles promoted endothelial ferroptosis and barrier disruption.
- GBP2 bound OTUD5 and promoted GPX4 ubiquitination.
- Plantainoside D disrupted the GBP2–OTUD5 interaction and reduced experimental lung injury.
6. Fluoxetine promotes IL-10-dependent metabolic defenses to protect from sepsis-induced lethality.
Preclinical studies showed that fluoxetine increased circulating IL-10 independently of peripheral serotonin, prevented sepsis-associated hypertriglyceridemia and cardiac metabolic dysfunction, and reduced mortality in animal models. IL-10 was necessary for the protective immunometabolic effect.
Impact: The study linked immune regulation, lipid metabolism, and cardiac dysfunction through a repurposable approved drug. It provided a clearly testable mechanism for host-directed therapy.
Clinical Implications: The findings justify carefully designed phase 2 studies with IL-10, triglyceride, cardiac, and safety endpoints. They do not support routine fluoxetine use in sepsis before human efficacy studies.
Key Findings
- Fluoxetine increased circulating IL-10 independently of peripheral serotonin.
- IL-10 was required to prevent hypertriglyceridemia and cardiac metabolic dysfunction.
- Fluoxetine reduced sepsis-induced lethality in preclinical models.
7. Utilising routinely collected clinical data through time series deep learning to improve identification of bacterial bloodstream infections: a retrospective cohort study.
In 20,850 patients, an LSTM model using up to 14 days of laboratory trajectories predicted pathogenic bloodstream infection with an AUROC of 0.97 in temporal hold-out testing. Longitudinal CRP, eosinophil, and platelet patterns were important predictors, and the time-series model outperformed static models.
Impact: The study demonstrated that routinely collected longitudinal data can support high-performance, individualized bloodstream infection prediction before culture confirmation. Its principal contribution was methodological and implementation-oriented.
Clinical Implications: An externally validated model could prioritize cultures, molecular testing, antimicrobial escalation, or de-escalation. Prospective studies must determine whether alerts improve outcomes without increasing unnecessary antibiotic use.
Key Findings
- The LSTM model achieved an AUROC of 0.97 and an AUPRC of 0.65 in temporal hold-out testing.
- Longitudinal CRP, eosinophil, and platelet patterns were important predictors.
- The time-series model outperformed static logistic models, especially for hospital-acquired bloodstream infection.
8. Elevated levels of S100A8 and S100A9 exacerbate muscle mitochondrial fragmentation in sepsis-induced muscle atrophy.
This translational study linked sepsis-associated muscle atrophy to an S100A8/A9–RAGE–Drp1 pathway that promotes mitochondrial fission and myocyte atrophy. Clinical muscle-index changes were associated with 60-day mortality, while pathway inhibition improved mitochondrial function and reduced atrophy in experimental models.
Impact: The paper connected a clinically important long-term complication with a defined and potentially druggable molecular pathway. It integrated patient outcome data with mechanistic and intervention evidence.
Clinical Implications: S100A8/A9 may identify patients at risk of ICU-acquired weakness, while RAGE or Drp1 modulation warrants early translational study. Effects on antimicrobial defense and optimal treatment timing require evaluation.
Key Findings
- Skeletal muscle index change was independently associated with 60-day mortality in septic patients.
- Sepsis increased S100A8/A9 expression and mitochondrial dysfunction in skeletal muscle.
- S100A8/A9 activated RAGE and Drp1-dependent mitochondrial fragmentation, while pathway inhibition reduced atrophy.
9. Single-Cell Landscape of Bronchoalveolar Lavage Fluid Identifies Specific Neutrophils during Septic Immunosuppression.
Single-cell RNA sequencing of patient-derived bronchoalveolar lavage fluid identified a neutrophil-dominated immunosuppressive program in sepsis. Five neutrophil subpopulations expanded during the immunosuppressive phase, highlighting pulmonary immune heterogeneity and potential targets for preventing secondary infection.
Impact: The study moved immune monitoring beyond total cell counts toward organ-specific cellular states. It provided high-resolution human evidence relevant to precision immunology.
Clinical Implications: The findings may support immune-monitoring panels and strategies that preserve antimicrobial defense while limiting immunosuppressive neutrophil states. Larger cohorts and outcome correlation are required.
Key Findings
- Single-cell sequencing revealed a neutrophil-driven pulmonary immunosuppressive program.
- Five distinct neutrophil subpopulations expanded during septic immunosuppression.
- The results prioritized neutrophil-state biology for preventing secondary pulmonary infection.
10. Prevalence, aetiology, and hospital outcomes of paediatric acute critical illness in resource-constrained settings (Global PARITY): a multicentre, international, point prevalence and prospective cohort study.
This multinational study included 7,538 children across 19 countries and found that acute critical illness affected 13.1% of hospitalized children, rising to 28.0% in low-SDI countries. Sepsis or septic shock accounted for 10.4% of acute critical illness, and 59% of deaths occurred within 48 hours.
Impact: The study provided a large, geographically diverse description of pediatric critical illness and identified an early high-risk window in resource-constrained settings. Its main contribution was knowledge advancement and global generalizability.
Clinical Implications: Health systems should strengthen early triage, oxygenation, antibiotics, fluids, and basic organ support, while implementation research evaluates scalable approaches. Resource allocation should be guided by local epidemiology.
Key Findings
- Acute critical illness affected 13.1% of hospitalized children overall and 28.0% in low-SDI countries.
- Sepsis and septic shock accounted for 10.4% of pediatric acute critical illness.
- Fifty-nine percent of deaths occurred within the first 48 hours.