Daily Sepsis Research Analysis
Three studies advance sepsis science across therapy, delivery, and stratification. A mechanistic study shows fluoxetine confers IL-10–dependent immunometabolic protection from sepsis lethality. A DNA-based nanorobot targets and hitchhikes neutrophils via CXCR2 to dampen inflammation and reduce tissue injury, while a secondary analysis of an RCT finds therapeutic plasma exchange modulates inflammatory mediators and suggests cell-free DNA may identify patients most likely to benefit.
Summary
Three studies advance sepsis science across therapy, delivery, and stratification. A mechanistic study shows fluoxetine confers IL-10–dependent immunometabolic protection from sepsis lethality. A DNA-based nanorobot targets and hitchhikes neutrophils via CXCR2 to dampen inflammation and reduce tissue injury, while a secondary analysis of an RCT finds therapeutic plasma exchange modulates inflammatory mediators and suggests cell-free DNA may identify patients most likely to benefit.
Research Themes
- Host-directed therapy via immunometabolic modulation
- Neutrophil-targeted nanomedicine for inflammatory control
- Biomarker-guided selection for extracorporeal blood purification
Selected Articles
1. Fluoxetine promotes IL-10-dependent metabolic defenses to protect from sepsis-induced lethality.
In preclinical models, fluoxetine protects against sepsis lethality by elevating circulating IL-10, independent of peripheral serotonin, thereby preventing sepsis-induced hypertriglyceridemia and cardiac metabolic dysfunction. The study defines an immunometabolic defense mechanism with repurposing potential for a widely used SSRI.
Impact: Identifies a concrete IL-10–mediated mechanism linking SSRI exposure to sepsis protection, suggesting a readily testable, host-directed therapy. It bridges immunology, metabolism, and psychopharmacology with high translational promise.
Clinical Implications: Do not change practice yet, but the data justify prospective, controlled trials testing fluoxetine as adjunctive therapy in sepsis with IL-10 and cardiometabolic endpoints. Patient selection, dosing, and safety (e.g., QT risk, bleeding) require careful evaluation.
Key Findings
- Fluoxetine-mediated protection from sepsis is independent of peripheral serotonin signaling.
- Fluoxetine increases circulating IL-10, which is necessary for protection against sepsis-induced hypertriglyceridemia.
- IL-10–dependent effects prevent cardiac glucose oxidation impairment, ectopic lipid accumulation, ventricular stretch, and possible cardiac failure.
Methodological Strengths
- Mechanistic linkage established using cytokine dependence to demonstrate necessity of IL-10.
- Integration of immunologic and metabolic readouts to connect systemic inflammation to cardiac function.
Limitations
- Preclinical study without randomized clinical validation.
- Dosing, timing, and safety profile for sepsis populations were not defined.
Future Directions: Conduct phase 2 randomized trials of fluoxetine as adjunctive therapy in sepsis, stratified by baseline IL-10 levels and cardiometabolic phenotypes; delineate central versus peripheral mechanisms and define optimal dosing windows.
Selective serotonin reuptake inhibitors (SSRIs) are some of the most prescribed drugs in the world. While they are used for their ability to increase serotonergic signaling in the brain, SSRIs are also known to have a broad range of effects beyond the brain, including immune and metabolic effects. Recent studies have demonstrated that SSRIs are protective in animal models and humans against several infections, including sepsis and COVID-19; however, the mechanisms underlying this protection are largely unknown. Here, we mechanistically link two previously described effects of the SSRI fluoxetine in mediating protection against sepsis. We show that fluoxetine-mediated protection is independent of peripheral serotonin and instead increases levels of circulating interleukin-10 (IL-10). IL-10 is necessary for protection from sepsis-induced hypertriglyceridemia, preventing cardiac effects including impairment of glucose oxidation, ectopic lipid accumulation, ventricular stretch and possibly cardiac failure. Our work reveals a beneficial "off-target" effect of fluoxetine, and reveals a protective immunometabolic defense mechanism with therapeutic potential.
2. A DNA-based nanorobot for targeting, hitchhiking, and regulating neutrophils to enhance sepsis therapy.
An Ac-PGP–modified tetrahedral DNA nanorobot binds neutrophil CXCR2, hitchhikes to inflamed tissues, and reprograms neutrophil maturation and functions to reduce oxidative stress and inflammatory recruitment, markedly decreasing sepsis-induced tissue damage in vivo. This demonstrates precise neutrophil-targeted delivery and regulation as a therapeutic concept.
Impact: Introduces a programmable, cell-specific nanoplatform that leverages leukocyte trafficking to overcome delivery and off-target constraints in sepsis. It could generalize to other neutrophil-driven conditions.
Clinical Implications: While preclinical, the platform suggests a path to neutrophil-directed therapeutics that co-opt physiological trafficking. Translation will require immunogenicity, biodistribution, toxicity, and manufacturability assessments under GLP/GMP conditions.
Key Findings
- Ac-PGP–modified tetrahedral framework nucleic acid (APT) specifically binds neutrophil CXCR2 and hitchhikes to inflammatory sites, extending effective half-life.
- Internalized APT modulates neutrophil cell cycle and maturation, regulating oxidative stress, inflammation, migration, and recruitment in vitro and in vivo.
- In sepsis models, targeted neutrophil regulation by APT substantially reduced tissue damage.
Methodological Strengths
- Rational receptor targeting (CXCR2) with a defined peptide ligand on a structurally controlled DNA nanoframe.
- Convergent validation across in vitro and in vivo inflammation/sepsis models with functional readouts.
Limitations
- Preclinical study without human data; immunogenicity and off-target effects on other CXCR2-expressing cells remain unknown.
- Long-term safety, clearance, and large-scale manufacturing feasibility not addressed.
Future Directions: Profile immunogenicity/toxicity and pharmacokinetics in large animals; evaluate efficacy in polymicrobial sepsis and comorbidity models; consider cargo loading or combinatorial immunomodulation.
Targeted regulation of neutrophils is an effective approach for treating neutrophil-driven inflammatory diseases, but challenges remain in minimizing off-target effects and extending drug half-life. A DNA-based nanorobot was developed to target neutrophils by using an N-acetyl Pro-Gly-Pro (Ac-PGP) peptide to specifically bind to the C-X-C motif of chemokine receptor 2 (CXCR2) on neutrophil membranes. This robot (a tetrahedral framework nucleic acid modified with Ac-PGP, APT) identified and hitchhiked neutrophils to accumulate at inflammatory sites and prolong its half-lives, whilst also was internalized to influence the neutrophil cell cycle and maturation process to regulate oxidative stress, inflammation, migration, and recruitment in both in vivo and in vitro inflammation experiments. Consequently, the tissue damage caused by sepsis was greatly reduced. This novel neutrophil-based nanorobot highlights the high precision of targeting and regulating neutrophils, and presents a potential strategy for treating multiple neutrophil-driven diseases.
3. The effect of therapeutic plasma exchange on the inflammatory response in septic shock: a secondary analysis of the EXCHANGE-1 trial.
In early septic shock, adjunctive plasma exchange reduced acute-phase proteins (CRP, PTX3) and IL-2Rα/CD25 but did not uniquely lower pro-inflammatory cytokines versus standard care. Rising cfDNA within 6 hours signaled refractoriness to standard care, whereas plasma exchange recipients showed sustained reductions in norepinephrine and lactate.
Impact: Links a modifiable intervention (plasma exchange) to specific immune mediators and proposes cfDNA as a pragmatic biomarker to select patients likely to benefit, enabling precision use of extracorporeal therapies.
Clinical Implications: Consider measuring early cfDNA kinetics in septic shock as a prognostic marker of refractoriness to standard care and to guide enrollment into trials of plasma exchange. Routine TPE use awaits prospective validation of biomarker-guided strategies.
Key Findings
- Therapeutic plasma exchange significantly reduced CRP and PTX3; IL-2Rα/CD25 decreased, while TNF-α/IL-6/IL-8 declined similarly in both arms.
- Rising cfDNA within the first 6 hours identified refractoriness to standard care regarding norepinephrine and lactate reduction.
- Patients receiving plasma exchange exhibited sustained decreases in norepinephrine dose and lactate compared with standard care.
Methodological Strengths
- Secondary analysis nested within a randomized design with pre/post sampling of immune mediators.
- Use of mixed-effects and multivariate modeling to relate biomarkers to hemodynamic endpoints.
Limitations
- Secondary, exploratory analysis with likely limited sample size and without mortality-powered endpoints.
- Single TPE session; external validity and optimal treatment intensity remain undetermined.
Future Directions: Prospective trials using cfDNA-guided enrollment to test whether TPE improves patient-centered outcomes; mechanistic work to dissect why IL-2Rα/CD25 responds while canonical cytokines do not.
BACKGROUND: Sepsis and septic shock, defined by a profound immune dysregulation, are among the leading causes of death in the intensive care unit (ICU). Despite advances in understanding the underlying pathophysiology, evidence for specific immunomodulatory treatment does not exist to date. Therapeutic plasma exchange (TPE) represents an adjunctive treatment approach to rebalance immune homeostasis. In the EXCHANGE-1 trial, we recently demonstrated a rapid hemodynamic improvement, possibly caused by the removal of harmful mediators and the replacement of protective plasma proteins. The aim of this secondary analysis is to further characterize the underlying immunomodulatory effects and to identify biomarkers that may predict treatment response. METHODS: This secondary analysis included patients in early septic shock (< 24 h duration) and a norepinephrine (NE) dose of ≥ 0.4 μg/kg/min. Patients were randomized 1:1 to receive standard of care (SOC) or SOC + one single TPE and plasma samples were collected before and after TPE. Within-group and between group effects of circulating levels of acute-phase proteins [CRP and Pentraxin3 (PTX3)], inflammatory mediators (IL-4, IL-6, IL-8, IL-10, TNF-α, IL-2Rα/CD25) and damage-associated molecular pattern (DAMP) [cell-free DNA (cfDNA)] were analyzed via paired t test or Wilcoxon signed-rank test and a mixed-effects model. Multivariate mixed-effects modeling of NE and lactate reduction was performed to investigate if cfDNA could be associated with treatment response to TPE. RESULTS: TPE led to a significant reduction in circulating acute-phase protein levels (CRP p = 0.00976, PTX3 p = 0.0001). Pro-inflammatory cytokines, such as circulating TNF-α-, IL-6- und IL-8-levels, were significantly reduced in both groups with no significant difference between treatment groups except for IL-2Rα/CD25 (p ≤ 0.0001). In a multivariate mixed-effects model, rising cfDNA levels over the first 6 h indicated refractoriness to SOC treatment regarding NE (p = 0.004) and lactate (p = 0.001), whereas those receiving TPE demonstrated sustained reductions in both parameters. CONCLUSIONS: In this secondary analysis of the EXCHANGE-1 trial adjunctive TPE is associated with the reduction of acute-phase proteins and IL-2Rα/CD25, however not with the reduction of pro-inflammatory cytokines. This phenomenon could contribute to the observed enhancement in hemodynamics among patients with septic shock. Furthermore, TPE may be particularly beneficial for patients with septic shock who exhibit rising levels of cfDNA.