Daily Sepsis Research Analysis
Three high-impact sepsis papers emerged today: a large meta-analysis defines the time course and mortality risk of echocardiographic phenotypes in sepsis, while two mechanistic studies propose targeted immunomodulation—epigenetic tuning of NETs via HDAC2/CARM1 and macrophage-directed lncRNA Nron therapy using lipid nanoparticles. Together, they refine risk stratification and suggest translational therapeutic avenues.
Summary
Three high-impact sepsis papers emerged today: a large meta-analysis defines the time course and mortality risk of echocardiographic phenotypes in sepsis, while two mechanistic studies propose targeted immunomodulation—epigenetic tuning of NETs via HDAC2/CARM1 and macrophage-directed lncRNA Nron therapy using lipid nanoparticles. Together, they refine risk stratification and suggest translational therapeutic avenues.
Research Themes
- Temporal phenotyping of sepsis-induced cardiac dysfunction by echocardiography
- Epigenetic regulation of neutrophil NETs in infectious versus inflammatory sepsis
- Noncoding RNA–based, macrophage-targeted immunotherapy for sepsis
Selected Articles
1. Time Course of Morbidity and Mortality Across Echocardiographic Phenotypes in Patients With Sepsis: A Systematic Review and Meta-Analysis.
Across 65 studies (n=17,008), echocardiographic LVSD, LVDD, and RVD peaked within 48 hours of sepsis onset and declined by 72 hours, displaying a parabolic-like trajectory. Each phenotype independently increased mortality risk (RRs ~1.36–1.62), supporting time-sensitive, serial echocardiographic assessment for prognostication.
Impact: It consolidates heterogeneous literature to define when and how sepsis-related myocardial dysfunction emerges and links these phenotypes to mortality, guiding risk stratification and monitoring strategies.
Clinical Implications: Adopt serial echocardiography within the first 72 hours to detect LVSD, LVDD, and RVD and incorporate these phenotypes into mortality risk stratification and hemodynamic management decisions.
Key Findings
- LVSD occurrence peaked at 33% within 48 h and fell to 22% by 72 h.
- LVDD occurrence rose to 46% within 48 h and was 44% at 72 h.
- RVD occurrence peaked at 47% within 48 h and decreased to 33% by 72 h.
- Each phenotype increased mortality risk: LVSD RR 1.57, LVDD RR 1.36, RVD RR 1.62.
Methodological Strengths
- Large-scale meta-analysis of 65 studies with 17,008 patients across 18 regions
- Time-stratified analysis across echocardiographic phenotypes and testing mortality associations
Limitations
- Substantial heterogeneity in echocardiographic definitions and timing across studies
- Predominantly observational data with residual confounding
Future Directions: Prospective, standardized echocardiography protocols to validate time windows and interventional trials testing phenotype-guided hemodynamic strategies.
OBJECTIVES: To determine the temporal evolution of morbidity and mortality across different echocardiographic phenotypes of new-onset myocardial dysfunction in patients with sepsis. DATA SOURCES: PubMed, Embase, Web of Science, MEDLINE, the Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to October 1, 2024. STUDY SELECTION: All original studies related to new-onset myocardial dysfunction diagnosed by echocardiography in adult patients with sepsis were included. DATA EXTRACTION: Data were collected according to the predefined outcomes. DATA SYNTHESIS: This systematic review included 65 studies from 18 regions, involving 17,008 patients with sepsis. The meta-analysis encompassed three echocardiographic phenotypes, namely left ventricular systolic dysfunction (LVSD), left ventricular diastolic dysfunction (LVDD), and right ventricular dysfunction (RVD), as well as four subgroups based on different echocardiographic time points. No patients had cardiac dysfunction at baseline, and the occurrence rate of heart dysfunction declined to a minimal level during the recovery phase. The occurrence rate of LVSD peaked at 33% (95% CI, 27-40%) within 48 hours and declined to 22% (95% CI, 18-25%) within 72 hours. The occurrence rate of LVDD rose to 46% (95% CI, 34-57%) within 48 hours and dropped to 44% (95% CI, 32-56%) within 72 hours. The occurrence rate of RVD peaked at 47% (95% CI, 37-58%) within 48 hours and decreased to 33% (95% CI, 3-75%) within 72 hours. Patients with LVSD, LVDD, or RVD showed a higher risk of death (LVSD: relative risk [RR], 1.57 [95% CI, 1.29-1.91], p < 0.0001; LVDD: RR, 1.36 [95% CI, 1.05-1.75], p = 0.02; and RVD: RR, 1.62 [95% CI, 1.35-1.95], p < 0.0001). CONCLUSIONS: This meta-analysis shows a parabolic-like pattern of the occurrence rate of echocardiographic phenotypes (LVSD, LVDD, and RVD) over the time course of sepsis. LVSD, LVDD, and RVD are significant risk factors for mortality in sepsis.
2. HDAC2 enhances the antimicrobial activity of neutrophils by promoting the formation of neutrophil extracellular traps (NETs) in sepsis.
HDAC2 is upregulated in sepsis and promotes NET formation via histone mark reprogramming, enhancing antimicrobial defense. While HDAC2 inhibition reduces inflammation but compromises survival in infectious sepsis, combined HDAC2/CARM1 inhibition balances antimicrobial activity with anti-inflammation, improving survival in CLP mice.
Impact: Identifies an epigenetic mechanism linking HDAC2 to NET biology and demonstrates a rational dual-target strategy that improves survival in preclinical sepsis, opening a therapeutic avenue.
Clinical Implications: Suggests that indiscriminate HDAC2 inhibition may be detrimental in infectious sepsis, whereas rational combinations (e.g., HDAC2 plus CARM1 inhibition) could preserve antimicrobial function while limiting inflammation—hypotheses for early-phase clinical testing.
Key Findings
- HDAC2 expression is elevated in patients and mice with sepsis.
- HDAC2 knockout/inhibition reduces NET formation and antimicrobial activity, lowering survival in infectious sepsis but reducing inflammation in non-infectious models.
- HDAC2 promotes NETs via decreased H3K18 acetylation and inhibition of CARM1-mediated H3R17 methylation, facilitating H3R17 citrullination.
- Dual inhibition of HDAC2 and CARM1 suppresses inflammation, preserves antimicrobial activity, and improves survival in CLP-induced sepsis.
Methodological Strengths
- Use of both genetic (HDAC2 knockout) and pharmacologic inhibition across CLP and LPS sepsis models
- Multi-modal assays (flow cytometry, immunofluorescence, western blot) with mechanistic histone modification analysis
Limitations
- Preclinical murine and in vitro data; human functional validation is lacking
- Safety, dosing, and off-target effects of dual HDAC2/CARM1 inhibition remain uncharacterized
Future Directions: Validate in human neutrophils from septic patients, assess pharmacology/toxicity of dual inhibitors, and design early-phase trials with infection-status stratification.
INTRODUCTION: Sepsis is characterized as a life-threatening organ dysfunction resulting from a dysregulated host response to infection, representing a critical clinical syndrome. Uncontrolled infection and inflammation are two main characteristics of sepsis. Neutrophil extracellular traps (NETs) is a major mechanism by which neutrophils resist pathogens invasion, but the mechanism of the NETs formation remain completely unclear. OBJECTIVES: This study aims to elucidate the role of Histone Deacetylase 2 (HDAC2) in NETs formation and its impact on antimicrobial and anti-inflammatory activities in sepsis. METHODS: We employed flow cytometry, immunofluorescence and western blotting to assess NETs formation. The effects of HDAC2 on NETs and sepsis outcomes were investigated using an HDAC2 inhibitor and HDAC2 knockout mice in CLP-induced and LPS-induced sepsis models. Histone modifications in neutrophils were also analyzed to explore HDAC2's regulatory mechanism. RESULTS: HDAC2 was found to be highly expressed in patients and mice with sepsis. While HDAC2 knockout or inhibition reduced inflammation and improved organ function in non-infectious sepsis, it decreased survival in infectious sepsis. In addition, knockout or inhibition of HDAC2 significantly reduced the NETs formation, and impaired the antimicrobial activities against E. coli infection in mice. Mechanistically, HDAC2 indirectly promoted H3R17 citrullination to induce the NETs formation through down-regulating H3K18 acetylation and interactively inhibiting CARM1-mediated H3R17 methylation in neutrophils. Furthermore, a dual inhibition strategy targeting HDAC2 and CARM1 not only suppressed inflammation, prevented from multiple organ dysfunction, but also enhanced the antimicrobial activities, which finally improved survival rate of mice with sepsis induced by cecal ligation and puncture (CLP). CONCLUSION: Our findings reveal a novel role for HDAC2 in modulating anti-infectious immunity through NETs formation during sepsis. This study provides a potential therapeutic strategy for sepsis by enhancing both antimicrobial and anti-inflammatory responses, offering a promising approach to preserve organ function and improve survival.
3. Long noncoding RNA Nron and its functional motif modulate macrophage-mediated inflammatory response.
Macrophage Nron restrains excessive inflammation by enhancing SIRT1 and suppressing NF-κB signaling; loss worsens, while gain improves survival in LPS/CLP sepsis models. A conserved Nron motif (NCM2) delivered by macrophage-targeted LNPs ameliorated sepsis in mice, highlighting a translational ncRNA therapy approach.
Impact: Demonstrates a mechanistically grounded, macrophage-targeted lncRNA therapy that improves outcomes in sepsis models, bridging basic RNA biology and translational immunotherapy.
Clinical Implications: Supports development of macrophage-directed ncRNA therapeutics to rebalance inflammation in sepsis; informs biomarker strategies around Nron/miR-146a-3p/miR-16-1-3p/SIRT1 axes.
Key Findings
- Myeloid-specific Nron knockout exacerbates LPS/CLP-induced sepsis; transgenic overexpression confers survival benefit with reduced tissue inflammation.
- Nron enhances SIRT1 activity by sponging miR-146a-3p/miR-16-1-3p, thereby suppressing NF-κB p65 acetylation/phosphorylation (directly or via HIF-1 signaling).
- A conserved Nron motif (NCM2) with longer half-life, delivered via macrophage-targeted LNPs, alleviated sepsis in mice.
Methodological Strengths
- Conditional knockout/knockin mouse models across LPS and CLP sepsis with mechanistic assays
- Therapeutic validation using macrophage-targeted LNP delivery and use of patient-derived monocytes/serum
Limitations
- Preclinical data; human in vivo safety, dosing, and biodistribution of LNP-NCM2 remain unknown
- Potential off-target interactions of ncRNA and microRNA networks not fully mapped
Future Directions: GLP toxicology and pharmacokinetics of LNP-NCM2, target engagement biomarkers, and phase 1 studies with macrophage-targeting readouts.
INTRODUCTION: Non-resolving macrophage-mediated inflammation is closely linked to the pathogenesis of systemic inflammatory response syndrome. Despite years of clinical trials attempting to mitigate the harmful effects of excessive inflammation, these efforts have largely been unsuccessful. Therefore, it is essential to develop novel therapeutic strategies. OBJECTIVE: To explore the role of Nron in inflammatory diseases and evaluate the therapeutic effect. METHODS: Conditional knockout/knockin mice were used for a systematic evaluation of Nron function in lipopolysaccharide (LPS) or cecal ligation and puncture (CLP)-induced sepsis. Quantitative real-time PCR, western blot, luciferase reporter assay, and RNA-RNA interaction assay were performed to investigate mechanisms and identify functional motifs. An enhanced lipid nanoparticle (LNP) formulation was constructed for targeted macrophage delivery and therapy. Moreover, monocytes were obtained from blood of patients with sepsis for in vitro culture, and the serum for enzyme-linked immunosorbent assay (ELISA) detection. Data analysis was conducted using GraphPad Prism 8. RESULTS: Conditional knockout of Nron in myeloid cells exacerbates LPS or CLP-induced sepsis, while the conditional transgenic mice exhibited a survival advantage with alleviated tissue inflammation and damage. Nron enhances sirtuin 1 (SIRT1) deacetylase activity via sponging miR-146a-3p/miR-16-1-3p in macrophages, thus regulating on nuclear factor kappa B (NF-κB) signaling by inhibiting p65 acetylation/phosphorylation directly or via HIF-1 signaling. The conserved functional motif of Nron (NCM2) has a longer half-life and LNP-NCM2 targeted to macrophages effectively alleviated sepsis in mice. CONCLUSION: Nron serves as a crucial negative regulator of excessive inflammatory responses, and its functional motifs can be used as a potential therapeutic agent for inflammatory diseases such as sepsis.