Weekly Sepsis Research Analysis
This week’s sepsis literature emphasizes immunometabolic drivers and translational host-target strategies. High-impact preclinical and translational studies nominate acyl‑CoA–binding protein (ACBP/DBI) as a circulating biomarker and therapeutic target, show lactic acid–driven intracellular acidification as a potent activator of NLRP3 and direct cytokine processing, and identify a terminally differentiated HIF‑1A–driven FOLR3+ neutrophil subset that predicts mortality. Together these papers push
Summary
This week’s sepsis literature emphasizes immunometabolic drivers and translational host-target strategies. High-impact preclinical and translational studies nominate acyl‑CoA–binding protein (ACBP/DBI) as a circulating biomarker and therapeutic target, show lactic acid–driven intracellular acidification as a potent activator of NLRP3 and direct cytokine processing, and identify a terminally differentiated HIF‑1A–driven FOLR3+ neutrophil subset that predicts mortality. Together these papers push toward biomarker‑guided, host‑directed therapies and refined immune phenotyping for prognosis and targeted interventions.
Selected Articles
1. Acyl-CoA-binding protein (ACBP): a poor-prognosis biomarker in sepsis and a target for disease mitigation.
This translational study shows plasma ACBP/DBI is elevated in septic patients and associates with organ dysfunction and mortality. Genetic deletion or monoclonal antibody neutralization of ACBP in multiple murine sepsis models reduced cytokine storm, preserved organ function, improved bacterial clearance, restored thermoregulation, and lowered mortality; effects were additive with glucocorticoids.
Impact: Identifies ACBP/DBI as a mechanistic amplifier of sepsis with orthogonal validation (human biomarker association, genetic deletion, antibody neutralization) and reproducible survival benefit across models—making it a high‑priority translational target.
Clinical Implications: ACBP/DBI could serve both as a prognostic biomarker and as a therapeutic target; first‑in‑human dose‑escalation studies of neutralizing antibodies (with biomarker enrichment and safety monitoring) are justified.
Key Findings
- Plasma ACBP/DBI levels are elevated in septic patients and correlate with organ dysfunction and mortality.
- Genetic deletion or monoclonal antibody neutralization of ACBP/DBI reduces cytokine storm, preserves organ function, restores thermoregulation, improves bacterial clearance, and lowers mortality across endotoxemia, E. coli, and polymicrobial sepsis models.
- Combination of ACBP/DBI inhibition with glucocorticoids further improved survival and reversed multi-organ shock signatures.
2. Lactic acid drives NLRP3 inflammasome activation and caspase-1-like cytokine cleavage via intracellular acidification.
Mechanistic work demonstrates that intracellular lactic acidification promotes NLRP3 inflammasome assembly via mitochondrial dysfunction, ROS and PKR phosphorylation, and that lactic acid can directly cleave pro‑IL‑1β/IL‑18 at caspase‑1‑like sites. In CLP sepsis models, systemic lactate worsened inflammation and survival, linking hyperlactatemia to detrimental innate immune activation.
Impact: Provides a unifying immunometabolic mechanism explaining how lactate links metabolism to inflammasome activation and cytokine maturation—clarifying a pathway that may mediate harm in hyperlactatemic sepsis and opening metabolic or PKR/NLRP3‑targeted interventions.
Clinical Implications: Motivates caution regarding iatrogenic lactate loading and supports testing interventions that limit intracellular acidification (buffering, LDH modulation, lactate efflux enhancement) or directly inhibit PKR–NLRP3 signaling in sepsis models and early trials.
Key Findings
- NLRP3 activators (nigericin/ATP) induce lactate production and intracellular acidification, promoting ASC speck formation, caspase‑1 activation, and IL‑1β release.
- Elevated extracellular lactate impairs lactate efflux, amplifying intracellular acidification; extracellular alkalinization abolishes inflammasome activation.
- Intracellular acidification triggers mitochondrial dysfunction, ROS, PKR phosphorylation and PKR–NLRP3 interaction; lactic acid directly cleaves pro‑IL‑1β at Asp116 and processes pro‑IL‑18.
- Systemic lactate administration worsened inflammation and survival in CLP sepsis models.
3. FOLR3+neutrophils contribute to sepsis by exacerbating hyper-inflammation.
Integrating single‑cell and bulk RNA‑seq, this study identifies a terminally differentiated FOLR3+ neutrophil subset with hyper‑inflammatory signatures and low HLA expression enriched in non‑survivors. HIF‑1A is implicated as a transcriptional driver; FOLR3+ neutrophils recruit platelets and amplify cytokine production, and higher proportions correlate with increased 28‑day mortality.
Impact: Defines a prognostically relevant neutrophil phenotype (FOLR3+) and identifies HIF‑1A as a regulatory node—providing new biomarker and target opportunities for modulating hyperinflammation in sepsis.
Clinical Implications: FOLR3+ neutrophil quantification may become a prognostic biomarker to enrich trials of anti‑inflammatory strategies; targeting HIF‑1A/FOLR3 pathways warrants exploration but requires assay standardization and prospective validation.
Key Findings
- Five neutrophil clusters identified; FOLR3+ neutrophils are terminally differentiated, hyper‑inflammatory, and show low HLA expression, especially in non‑survivors.
- Cell–cell communication analyses implicate RETN–CAP1 and NAMPT–ITGB1 axes for platelet recruitment driven by FOLR3+ neutrophils.
- Higher proportions of FOLR3+ neutrophils associate with increased 28‑day mortality; HIF‑1A manipulation altered FOLR3 expression and cytokine secretion in human and mouse neutrophils.