Daily Sepsis Research Analysis
Three studies advance sepsis science across epidemiology, immunology, and genetics. A large multicentre pediatric cohort shows Phoenix sepsis criteria enrich for severity but underestimate total burden. Single-cell profiling reveals γδ T-cell differentiation toward γδT17 with neutrophil-driven RETN–CAP1 signaling in pediatric sepsis, while Mendelian randomization links lipid traits to sepsis risk and nominates ANGPTL3/LPL as candidate drug targets.
Summary
Three studies advance sepsis science across epidemiology, immunology, and genetics. A large multicentre pediatric cohort shows Phoenix sepsis criteria enrich for severity but underestimate total burden. Single-cell profiling reveals γδ T-cell differentiation toward γδT17 with neutrophil-driven RETN–CAP1 signaling in pediatric sepsis, while Mendelian randomization links lipid traits to sepsis risk and nominates ANGPTL3/LPL as candidate drug targets.
Research Themes
- Pediatric sepsis epidemiology and diagnostic criteria
- Innate/adaptive immune cell reprogramming in sepsis
- Genetic causal inference of lipid pathways and drug targets in sepsis
Selected Articles
1. Epidemiology of community acquired sepsis in children in Australia and New Zealand: a multicentre prospective cohort study.
In a multicentre prospective cohort of children across Australia and New Zealand, only 0.8% had suspected sepsis and <0.1% met Phoenix criteria. Phoenix-positive cases had markedly higher organ support use and mortality, indicating strong enrichment for severe disease but underestimation of overall sepsis burden.
Impact: Provides high-quality, contemporary epidemiology using standardized Phoenix criteria across multiple centers, informing triage and resource planning in pediatric sepsis.
Clinical Implications: Phoenix criteria can enrich for severe pediatric sepsis requiring organ support, but clinicians should recognize that many sepsis cases may be missed if relying solely on Phoenix definitions; supplemental screening pathways are needed.
Key Findings
- Among 822,072 assessed children, 6232 (0.8%) had suspected sepsis and 306 (<0.1%) met Phoenix criteria.
- Phoenix-positive children had higher ICU admission (80.1% vs 17.3%), vasoactive infusions (47.1% vs 2.9%), mechanical ventilation (47.7% vs 4.0%), and ECLS (3.9% vs 0.2%).
- 90-day mortality was 1.4% overall (87/6232) and 13.7% among Phoenix-positive (42/306), indicating enrichment for severe disease but underestimation of total burden.
Methodological Strengths
- Prospective multicentre design across 11 hospitals with standardized application of Phoenix criteria
- Robust outcome capture including ICU therapies and 90-day mortality
Limitations
- Phoenix criteria may miss milder sepsis presentations, underestimating burden
- Findings from Australia/New Zealand may not generalize globally
Future Directions: Validate Phoenix-based pathways in diverse settings and develop adjunct screening tools to capture broader pediatric sepsis spectrum.
BACKGROUND: Paediatric sepsis epidemiology is unclear due to variability in case ascertainment. We describe the epidemiology of community acquired sepsis in Australian and New Zealand children using the Phoenix sepsis criteria. METHODS: Prospective observational study conducted in 11 hospitals through the Paediatric Research in Emergency Departments International Collaborative (PREDICT) Network from April 2021 to December 2023. Children aged 0-<18 years with suspected sepsis were included. Demographic information, therapies administered, and outcomes were collected, and the Phoenix sepsis criteria were applied. FINDINGS: Of 822,072 children assessed, 6232 (0.8%) children had suspected sepsis and 306 (<0.1%) met the Phoenix sepsis criteria. Children who met the Phoenix sepsis criteria had higher rates of intensive care unit admission (245/306; 80.1% vs 1080/6232; 17.3%), vasoactive infusion (144/306; 47.1% vs 179/6232; 2.9%) mechanical ventilation (146/306; 47.7% vs 251/6232; 4.0%), and extracorporeal life support (12/306; 3.9% vs 13/6232; 0.2%) compared to the overall cohort. Intensive care unit and hospital length of stay were longer for those meeting Phoenix sepsis criteria than for the overall cohort (median 48.4 h vs 79.8 h and 69.7 h vs 189.8 h, respectively). Overall, 87/6232 (1.4%) patients died within 90 days, 42/306 (13.7%) of whom met Phoenix sepsis criteria. INTERPRETATION: Hospitalisation for suspected sepsis was relatively infrequent. The Phoenix sepsis criteria identified children with more severe illness and worse outcomes, but underestimated the overall burden of sepsis. FUNDING: The National Health and Medical Research Council, the Medical Research Futures Fund, The Royal Children's Hospital Foundation, and the Victorian Government.
2. Single-cell RNA Sequencing In Pediatric Sepsis: γδ T Cell Exhibits A Differentiation To γδT17 Subtype Along With Significantly Enhanced Cell Communication With Neutrophils.
scRNA-seq of pediatric sepsis PBMCs shows γδ T cells adopt a proinflammatory state with increased activation and differentiation toward γδT17, validated by flow cytometry. Pseudotime and ligand–receptor analyses highlight seven candidate regulators and enhanced neutrophil resistin (RETN)–CAP1 signaling that may drive γδT17 polarization.
Impact: Reveals a previously underappreciated γδT17 polarization axis in pediatric sepsis and a plausible neutrophil–T-cell crosstalk mechanism (RETN–CAP1), opening avenues for targeted immunomodulation.
Clinical Implications: Identifies potential immunologic targets (e.g., resistin–CAP1 axis, regulators of γδT17 differentiation) and candidate biomarkers to stratify inflammatory phenotypes in pediatric sepsis.
Key Findings
- γδ T cells in pediatric sepsis display a proinflammatory state with elevated Th1 cytokine secretion and increased activation, validated by flow cytometry.
- Pseudotime analysis identified seven key genes potentially regulating γδ T-cell differentiation toward the γδT17 subtype.
- Cell–cell communication analysis showed enhanced RETN–CAP1 interactions between neutrophils and γδ T cells, implicating neutrophil-derived resistin in promoting γδT17 polarization.
Methodological Strengths
- Single-cell RNA sequencing with pseudotime and ligand–receptor analyses integrated with flow cytometric validation
- Focus on pediatric patient samples enhances disease relevance for this population
Limitations
- Sample size and cohort composition not specified; cross-sectional design limits causal inference
- Lack of in vivo functional validation of the RETN–CAP1 axis and γδT17 regulators
Future Directions: Validate RETN–CAP1 signaling and γδT17 regulators in larger pediatric cohorts and experimental models; assess therapeutic modulation of this axis.
Abnormal immune responses are common clinical features in septic patients. γδ T cells, as innate immune cells, play an important role in host defense, immune surveillance and homeostasis. However, the immune characteristics of γδ T cells in pediatric sepsis remains remain poorly understood. In this study, we analyzed single-cell RNA high-throughput sequencing data of peripheral blood mononuclear cells (PBMCs) from pediatric septic patients. It demonstrates that γδ T cells exhibit a proinflammatory state with heightened immune responsiveness to pathogens in pediatric sepsis, as confirmed by the results of flow cytometric analysis showing elevated Th1 cytokines secretion, increased activation, and a propensity to differentiate into IL-17-producing (γδT17) cells during disease progression. Pseudotime analysis identified seven key genes potentially regulating the differentiation of γδ T cells to γδT17 subtype. Furthermore, cell-cell communication analysis revealed enhanced RETN-CAP1 binding between neutrophils and γδ T cells in pediatric sepsis, suggesting that neutrophil-derived resistin may promote γδ T cell differentiation into the γδT17 subtype via CAP1 receptor binding. In conclusion, this study provides a single-cell study that analyzed the immune status of γδ T cells in pediatric sepsis, highlighting their pivotal roles in pathogen response, inflammation propagation, and immune regulation. The observed differentiation toward the γδT17 subtype may facilitate neutrophil recruitment in this life-threatening condition. Elucidating the molecular mechanisms of γδ T cells in pediatric sepsis could offer a new theoretical basis for novel therapeutics.
3. Genetic association of lipids characteristics and lipid lowering drug target genes with sepsis.
Two-sample Mendelian randomization indicates genetically higher ApoA-1, HDL-C, and total cholesterol are protective against sepsis, with consistent sensitivity analyses. Instrumented LDL-lowering near HMGCR/LDLR predicted higher sepsis risk, while reduced ANGPTL3/LPL activity was predicted to lower risk, nominating these pathways as therapeutic targets.
Impact: Provides causal inference linking lipid biology to sepsis susceptibility and prioritizes drug targets (ANGPTL3, LPL), challenging assumptions about LDL lowering and infection risk.
Clinical Implications: If validated, therapies modulating HDL/ApoA-1 or targeting ANGPTL3/LPL could reduce sepsis risk; caution may be warranted when profoundly lowering LDL-C in high-infection-risk populations.
Key Findings
- Genetically higher ApoA-1 associated with lower sepsis risk in individuals under 75 years (OR 0.927; 95% CI 0.861–0.999).
- Higher HDL-C associated with decreased sepsis risk (under 75: OR 0.897; 95% CI 0.838–0.960) and lower incidence overall (OR 0.883; 95% CI 0.820–0.951).
- LDL-lowering variants near HMGCR and LDLR predicted increased sepsis risk, whereas reduced ANGPTL3 and LPL activity predicted decreased risk.
Methodological Strengths
- Two-sample Mendelian randomization with multivariable MR and multiple sensitivity analyses
- Integration of eQTL data to mimic pharmacologic target modulation
Limitations
- MR relies on assumptions (e.g., no horizontal pleiotropy) that may be imperfectly met
- Summary-level GWAS prevent granular stratification; generalizability and age-specific effects warrant caution
Future Directions: Prospective validation of lipid-targeted interventions (e.g., ANGPTL3 inhibition) on infection/sepsis endpoints and mechanistic studies linking lipid transport to host defense.
BACKGROUND: Sepsis is a severe systemic infection that can result in organ dysfunction and mortality. Dyslipidemia emerges as a key player in the intricate web of sepsis pathogenesis. Yet, the causal relationship between blood lipid profiles and sepsis risk remains uncertain. This study aims to investigate the association between genetically predicted lipid traits, drug targets, and sepsis. METHODS: The UK Biobank's Genome-wide association studies (GWAS) produced data on lipid and apolipoprotein characteristics. Four independent GWAS datasets were used to generate the sepsis statistics. The study utilized the two-sample Mendelian randomization (MR) approach, which incorporates multivariable (MVMR) models, to assess the correlations between sepsis risk and lipid-related parameters. To gain further insight, expression quantitative trait loci (eQTL) data were used to investigate the significant drug targets for lipid-lowering. RESULTS: Increasing ApoA-1 levels was associated with a diminished risk of sepsis (under 75) (OR 0.927, 95% CI 0.861-0.999; p = 0.047). This inverse correlation persevered even after performing multivariable MR. Elevated levels of HDL-C were associated with a decreased risk of sepsis (under 75) (OR 0.897, 95% CI 0.838-0.960; P = 0.002) and incidence of sepsis (OR 0.883, 95% CI 0.820-0.951; P = 0.001), which was consistent across sensitivity analyses. Furthermore, a decrease in total cholesterol exhibited a causal effect on sepsis in multivariable MR (OR 0.779, 95% CI 0.642-0.944; P = 0.01). The genetic variants related to lowering LDL-C, located near the HMGCR and LDLR genes, were predicted to elevate the risk of sepsis. Moreover, genetic mimicry near the ANGPTL3 and LPL gene suggested that reducing the activity of ANGPTL3 and LPL (mimicking antisense anti-ANGPTL3 and LPL agents) was forecasted to decrease sepsis risk. CONCLUSION: Genetically inferred elevated ApoA-1, total cholesterol, and HDL-C manifest a protective effect against sepsis. Within the 9 lipid-lowering drug targets investigated ANGPTL3 and LPL exhibit potential as candidate drug targets for sepsis.