Daily Sepsis Research Analysis
Three high-impact sepsis studies advance mechanistic and translational understanding. A large multi-omic human cohort shows the anatomical source of infection imprints distinct immune programs. Two mechanistic studies reveal actionable targets: ERRγ-driven cardiomyocyte subtype conversion in sepsis-induced cardiomyopathy and a platelet–mast cell axis that triggers progression to septic shock.
Summary
Three high-impact sepsis studies advance mechanistic and translational understanding. A large multi-omic human cohort shows the anatomical source of infection imprints distinct immune programs. Two mechanistic studies reveal actionable targets: ERRγ-driven cardiomyocyte subtype conversion in sepsis-induced cardiomyopathy and a platelet–mast cell axis that triggers progression to septic shock.
Research Themes
- Anatomical site-specific immune programs in sepsis (multi-omics human cohort)
- Cardiomyocyte subtype conversion and ERRγ as a therapeutic node in sepsis-induced cardiomyopathy
- Platelet–mast cell signaling (PAF–chymase axis) as a driver of septic shock
Selected Articles
1. Single-cell multi-omic landscape reveals anatomical-specific immune features in adult and pediatric sepsis.
This large human cohort integrates single-cell transcriptomics, immune receptor sequencing, CITE-seq, bulk RNA-seq, and proteomics to show that the anatomical source of infection imprints distinct immune programs in sepsis across adults and children, including an NR4A2-linked signature. The dataset provides a reference map for site-specific immune states and candidate biomarkers.
Impact: Defines site-specific immune endotypes with multi-omic depth, enabling mechanistic stratification and biomarker discovery across age groups.
Clinical Implications: Supports risk stratification and targeted diagnostics by infection source; informs trial design using immune endotypes and may guide precision immunomodulation.
Key Findings
- Integrated single-cell and plasma multi-omics in 281 individuals revealed infection-site-specific immune programs.
- An NR4A2-associated immune signature was identified within sepsis immune states.
- Adult and pediatric sepsis shared core features but exhibited source- and age-specific immune differences.
Methodological Strengths
- Multi-omic integration (scRNA-seq, TCR/BCR-seq, CITE-seq, bulk RNA, proteomics)
- Large, mixed adult–pediatric human cohort enabling cross-age comparisons
Limitations
- Abstract suggests cross-sectional profiling; causal inferences are limited
- Details of external validation and clinical utility thresholds are not provided in the abstract
Future Directions: Prospective validation of site-specific immune endotypes to guide targeted therapies and development of clinically deployable biomarker panels.
The anatomical source of infection is a major determinant of sepsis outcomes; however, how distinct sites shape immunity remains unclear. Here we applied multi-omic profiling, integrating single-cell transcriptomics, single-cell T cell receptor and B cell receptor sequencing, CITE-seq, bulk RNA sequencing and plasma proteomics, to analyze peripheral blood mononuclear cells and plasma from 281 adult and pediatric individuals with sepsis and controls. We identified an NR4A2
2. Oestrogen-related receptor γ in sepsis-induced cardiomyopathy: role of cardiomyocyte subtype conversion.
Single-nucleus RNA-seq and cross-species models reveal that sepsis drives contractile cardiomyocytes into an injury-responsive subtype via ERRγ reduction, trading contractility for cytoprotection. ERRγ agonism after the acute phase reconverts cells to the contractile state, improving cardiac function; findings are validated in human hearts.
Impact: Introduces cardiomyocyte subtype conversion as a core SICM mechanism and positions ERRγ as a druggable node with demonstrated functional rescue in vivo.
Clinical Implications: Supports ERRγ-targeted therapeutics and timing strategies (post-acute-phase agonism) to restore contractility in SICM, informing translational trial design.
Key Findings
- Cardiomyocytes in normal hearts comprise contractile, injury-responsive, and transitional subtypes.
- Sepsis induces conversion of contractile to injury-responsive cardiomyocytes via ERRγ reduction, decreasing contractility but limiting ROS and injury.
- ERRγ agonist after the acute phase reconverts injury-responsive cardiomyocytes to contractile phenotype, improving function; validated in human hearts.
Methodological Strengths
- Single-nucleus RNA-seq with multi-species and multi-system validation (in vitro and in vivo)
- Mechanistic intervention using ERRγ agonist with functional readouts
Limitations
- Predominantly preclinical with translational validation; clinical trials are needed to confirm efficacy and safety
- Timing and dosing windows for ERRγ agonism require precise delineation in humans
Future Directions: Phase I/II studies of ERRγ agonists in SICM with biomarker-guided timing; mapping reversibility windows and interaction with standard sepsis care.
BACKGROUND AND AIMS: Sepsis remains one of the leading causes of death worldwide, and sepsis-induced cardiomyopathy (SICM) increases the overall mortality rate of sepsis patients. Currently, targeting therapies for SICM are lacking, due to the incomplete understanding of the pathophysiological mechanisms of SICM. Current research on the mechanisms of SICM remains at the level of the whole heart, lacking detailed studies at the single-cell levels. METHODS: Transcriptomic dynamics of cardiomyocytes and non-cardiomyocytes were examined in mice with caecal ligation and puncture (CLP)-induced sepsis model using single-nucleus RNA sequencing (snRNA-seq). Cultured neonatal rat ventricular myocytes, human embryonic stem cell-derived cardiomyocytes, and adult rat and human ventricular myocytes, and in vivo mouse models with myocardial injury induced by CLP (or lipopolysaccharide), were used to investigate the mechanisms of SICM. The findings of cardiomyocyte subtype conversion and its regulatory mechanisms were validated using human hearts. RESULTS: snRNA-seq analysis revealed that in normal hearts, cardiomyocytes were primarily divided into three major types: contractile cardiomyocytes, injury-responsive cardiomyocytes, and transitional cardiomyocytes. In both cultured cells (including neonatal rat ventricular myocytes, human embryonic stem cell-derived cardiomyocytes, adult rat ventricular myocytes, and adult human ventricular myocytes) and in vivo mouse model of sepsis, contractile cardiomyocytes converted into the injury-responsive subtype during the early stage of sepsis, which, although reducing myocardial contractility and impairing heart function, prevented sepsis-induced reactive oxygen species production and cell injury in cardiomyocytes. This subtype conversion of cardiomyocytes was driven by the reduction of oestrogen-related receptor γ (ERRγ) in contractile cardiomyocytes. In the CLP mouse model, after the acute phase of infection, ERRγ agonist promoted the conversion of injury-responsive cardiomyocytes back to the contractile type, improving cardiac function and prognosis in SICM. Finally, sepsis-elicited cardiomyocyte subtype conversion was confirmed in human hearts. CONCLUSIONS: This study not only identifies cardiomyocyte subtype conversions as a key pathophysiological basis for SICM-induced cardiac dysfunction but also establishes ERRγ as the central regulatory mechanism governing these conversions. Activating ERRγ has the potential to ameliorate cardiac dysfunction in SICM. This work provides new insights into the pathophysiology of SICM, offering novel therapeutic strategies for its prevention and treatment.
3. Platelet-mediated activation of perivascular mast cells triggers progression of sepsis to septic shock in mice.
In murine sepsis, platelets adhere to vascular walls and activate perivascular mast cells via PAF, driving hypotension, vascular leak, and microvascular dysfunction that culminate in septic shock. Blocking platelet/MC activation or inhibiting mast cell chymase prevents shock progression and reduces mortality, revealing a tractable pathway.
Impact: Identifies a causal platelet–mast cell axis and a druggable effector (chymase) for preventing septic shock progression.
Clinical Implications: Suggests therapeutic strategies targeting platelet adhesion/activation, mast cell activation, or chymase to prevent shock; supports biomarker development linking platelet dynamics and mast cell activation.
Key Findings
- Sepsis activates platelets to adhere to vascular walls and release PAF, stimulating perivascular mast cells.
- Mast cell activation correlates with shock and mechanistically drives hypotension, vascular leakage, and microvascular dysfunction.
- Inhibiting platelet or mast cell activation, or blocking mast cell chymase, prevents progression to shock and reduces mortality in septic mice.
Methodological Strengths
- Mechanistic dissection across mouse models with supportive human sample correlations
- Interventional experiments targeting multiple nodes (platelets, mast cells, chymase)
Limitations
- Predominantly murine; translational efficacy and safety of chymase inhibition need clinical testing
- The relative contribution of PAF versus other mediators may vary across sepsis etiologies
Future Directions: Early-phase trials of chymase inhibitors and strategies modulating platelet–mast cell interactions; development of biomarkers for mast cell activation in septic patients.
The critical events that trigger sepsis progression into life-threatening septic shock remain unclear. In agreement with reports that link a drop in platelet count to a complicated clinical course in sepsis patients, here we report that, during sepsis, mouse platelets become activated, deposit systemically on vascular walls, and stimulate perivascular mast cells (MC) by releasing platelet activating factor (PAF). In mouse models and patient samples, MC activation correlates with the development of shock in sepsis and is mechanistically linked to shock by inducing systemic hypotension, vascular leakage and microvascular perfusion abnormalities. Preventing platelet or MC activation, or inhibiting the activity of the major MC granule constituent chymase, averts progression from sepsis to shock and reduces mortality of septic mice. Thus, our work establishes that, during sepsis progression, platelet microvascular adhesion leads to MC-mediated vascular changes to culminate in septic shock and septic shock-associated mortality.