Daily Sepsis Research Analysis
Three papers advance sepsis science across mechanism, microbiome-targeted therapy, and rapid diagnostics. A Nature Communications study uncovers a cardiomyocyte lncRNA (Cpat) that preserves mitochondrial TCA cycle flux in sepsis-induced cardiomyopathy. Complementary work shows microbiota-derived acetic acid ameliorates elderly sepsis via FFAR2/NLRP3 signaling, while a volatolomics UVP-TOF MS method enables rapid species-level identification from positive blood cultures.
Summary
Three papers advance sepsis science across mechanism, microbiome-targeted therapy, and rapid diagnostics. A Nature Communications study uncovers a cardiomyocyte lncRNA (Cpat) that preserves mitochondrial TCA cycle flux in sepsis-induced cardiomyopathy. Complementary work shows microbiota-derived acetic acid ameliorates elderly sepsis via FFAR2/NLRP3 signaling, while a volatolomics UVP-TOF MS method enables rapid species-level identification from positive blood cultures.
Research Themes
- Mitochondrial metabolic regulation in sepsis-induced cardiomyopathy
- Microbiome-derived metabolites (acetic acid) and FFAR2/NLRP3 signaling in elderly sepsis
- Rapid volatolomics-based diagnostics for bloodstream infection
Selected Articles
1. Cardiomyocyte lncRNA Cpat maintains cardiac homeostasis and mitochondria function by targeting citrate synthase acetylation.
This mechanistic study identifies a cardiomyocyte-enriched lncRNA (Cpat) that preserves mitochondrial TCA cycle flux by inhibiting GCN5-mediated citrate synthase acetylation and stabilizing the MDH2-CS-ACO2 complex. Cpat protects against myocardial injury in sepsis-induced cardiomyopathy, highlighting a metabolic RNA-based therapeutic target.
Impact: Reveals a previously unrecognized RNA regulator of mitochondrial metabolism in sepsis-related cardiomyopathy with a clear enzymatic target (GCN5–CS). This opens a therapeutic avenue distinct from traditional anti-inflammatory approaches.
Clinical Implications: Although preclinical, targeting Cpat or the GCN5–citrate synthase acetylation axis could inform future therapies to prevent or treat sepsis-induced cardiac dysfunction by restoring mitochondrial metabolism.
Key Findings
- Identification of cardiomyocyte-enriched lncRNA Cpat as a regulator of mitochondrial TCA cycle flux.
- Cpat stabilizes the MDH2–CS–ACO2 complex by inhibiting GCN5-mediated acetylation of citrate synthase.
- Cpat attenuates myocardial injury in sepsis-induced cardiomyopathy, suggesting therapeutic potential.
Methodological Strengths
- Mechanistic dissection linking RNA regulation to enzyme acetylation and metabolic complex assembly.
- In vivo validation in sepsis-induced cardiomyopathy models alongside molecular assays.
Limitations
- Preclinical study without human validation or clinical endpoints.
- Translational challenges for lncRNA delivery, specificity, and safety remain unresolved.
Future Directions: Test Cpat modulation in large-animal sepsis models; evaluate druggable approaches to inhibit GCN5–CS acetylation; assess cardiac and systemic outcomes in early-phase clinical studies.
Myocardial energy metabolism disorders are essential pathophysiology in sepsis-associated myocardial injury. Yet, the underlying mechanisms involving impaired mitochondrial respiratory function upon myocardial injury remain poorly understood. Here we identify an unannotated and cardiomyocyte-enriched long non-coding RNA, Cpat (cardiac-protector-associated transcript), that plays an important role in regulating the dynamics of cardiomyocyte mitochondrial tricarboxylic acid (TCA) cycle. Cpat is essential to the mitochondrial respiratory function by targeting key metabolic enzymes and modulating TCA cycle flux. Specifically, Cpat enhances the association of TCA cycle core components malate dehydrogenase (MDH2), citrate synthase (CS), and aconitase (ACO2). Acetyltransferase general control non-repressed protein-5 (GCN5) acetylates CS and destabilizes the MDH2-CS-ACO2 complex formation. Cpat inhibits this GCN5 activity and facilitates MDH2-CS-ACO2 complex formation and TCA cycle flux. We reveal that Cpat-mediated mitochondrial metabolic homeostasis is vital in mitigating myocardial injury in sepsis-induced cardiomyopathy, positioning Cpat as a promising therapeutic target for preserving myocardial cellular metabolism and function.
2. Gut microbiota remodelling alleviates elderly sepsis by microbiota-derived acetic acid via FFAR2/NLRP3 pathway.
In elderly sepsis, dysbiosis with reduced acetic acid is linked to worse outcomes. Young-donor FMT or acetic acid supplementation improved barrier function and organ outcomes in aged CLP mice, with benefits mediated by FFAR2/NLRP3 inflammasome inactivation and abrogated by FFAR2 knockdown.
Impact: Provides translational evidence linking a specific microbiota-derived metabolite (acetic acid) and a host receptor (FFAR2) to outcome-relevant inflammation in elderly sepsis, identifying actionable therapeutic pathways.
Clinical Implications: Supports exploration of microbiome-based strategies (e.g., targeted FMT, prebiotics, or acetate donors) to modulate FFAR2/NLRP3 signaling in elderly sepsis, with attention to safety and patient selection.
Key Findings
- Elderly sepsis associated with reduced microbiota diversity, increased Escherichia-Shigella, and lower plasma acetic acid.
- Young-donor FMT increased Akkermansia, raised gut acetic acid, improved colon barrier, and outcomes in aged CLP mice.
- Acetic acid’s benefits on myocardium and organ function required FFAR2 and inactivation of NLRP3 inflammasome.
Methodological Strengths
- Integration of human observational data with aged mouse CLP models.
- Mechanistic validation using FFAR2 knockdown to demonstrate pathway dependence.
Limitations
- Human sample size and effect estimates are not reported; potential confounding in observational component.
- FMT/acetic acid interventions not tested in clinical trials; safety and feasibility in elderly septic patients remain unproven.
Future Directions: Prospective clinical studies to quantify acetic acid dynamics in elderly sepsis; early-phase trials of targeted FMT or acetate donors; pharmacologic FFAR2 agonists exploration with cardiac and systemic endpoints.
BACKGROUND: Elderly patients with sepsis have higher morbidity, mortality, and susceptibility than adults. Young-donor faecal microbiota transplantation (FMT) can remodel and improve intestinal dysbiosis to alleviate age-related diseases via microbiota-derived acetic acid and may be a treatment option for elderly sepsis. This study aimed to elucidate the influence of remodelling of the elderly gut microbiota on sepsis via acetic acid and explore the underlying mechanism. We analyzed the gut microbiota and plasma acetic acid in elderly patients with sepsis, performed young-donor FMT, and acetic acid supplementation in a caecum ligation and puncture-induced aged septic model mice, and assessed the effects of acetic acid on the septic myocardium by examining NLRP3 inflammasome in FFAR2 knockdown mice. RESULTS: Elderly sepsis had higher mortality, reduced gut microbiota diversity, increased Escherichia-Shigella abundance, and reduced plasma acetic acid levels. Young-donor FMT improved the gut microbiota, increased the abundance of the probiotic genus Akkermansia and faecal acetic acid levels in the gut, and improved colon barrier function and outcomes. Intestinal acetic acid intervention improved age-related intestinal dysbiosis, organ dysfunction, and adverse effects in aged septic mice. These beneficial effects on the myocardium were mediated by activation of the FFAR2/NLRP3 axis, as evidenced by the finding that FFAR2 knockdown abrogated the amelioration of acetic acid. The elderly gut microbiota is fragile, which is related to the severity and poor prognosis of elderly sepsis. CONCLUSION: Gut microbiota remodelling improves elderly sepsis via acetic acid, which can inhibit inflammatory reactions to alleviate myocardial damage by FFAR2/NLRP3 inflammasome inactivation.
3. Rapid detection of bloodstream infection bacteria directly from positive blood cultures by ultraviolet photoionization time-of-flight mass spectrometry.
Direct volatolomics profiling of positive blood cultures by UVP-TOF MS, coupled with stacked machine learning, achieved high Gram-level (0.96–0.98) and species-level (0.86–0.94) accuracy across aerobic/anaerobic conditions. This platform offers a rapid, automatable path to earlier organism identification.
Impact: Introduces a rapid, sensitive diagnostic pipeline that could shorten time-to-identification from flagged blood cultures, enabling earlier targeted antimicrobial therapy.
Clinical Implications: If validated prospectively, laboratories could implement UVP-TOF MS volatolomics to accelerate Gram/species calls and guide earlier narrowing of empiric therapy, antimicrobial stewardship, and sepsis care.
Key Findings
- UVP-TOF MS volatolomics directly analyzed volatile metabolites from positive blood culture bottles.
- Stacked generalization models achieved 0.96–0.98 accuracy for Gram classification and 0.86–0.94 for species classification across aerobic/anaerobic conditions.
- Identified characteristic bacterial metabolites supporting classification performance and potential automation.
Methodological Strengths
- Evaluation under both aerobic and anaerobic culture conditions with consistent performance.
- Use of stacked machine learning and metabolite feature elucidation to enhance interpretability.
Limitations
- External validation and broader species coverage are needed; sample size details are not provided.
- Clinical impact (time-to-effective therapy, outcomes) not assessed in prospective trials.
Future Directions: Prospective multicenter diagnostic accuracy and impact studies; expansion to polymicrobial cultures and resistant organisms; workflow integration and cost-effectiveness analyses.
BACKGROUND: Bloodstream infection (BSI) has a high incidence and mortality rate worldwide. Early diagnosis of pathogens is crucial for controlling disease progression and providing precise antibiotic treatment. Current clinical methods for identifying BSI pathogens are time-consuming and labor-intensive. RESULTS: This study introduced a novel bacterial identification method based on volatolomics analysis. Bacterial volatiles in positively flagged blood culture bottles of BSI were detected using an ultraviolet photoionization time-of-flight mass spectrometry (UVP-TOF MS). Both aerobic and anaerobic blood cultures were analyzed to obtain bacterial metabolic profiles. A stacked generalization algorithm was employed to construct classification models for BSI bacterial species. Bacterial volatiles differed significantly between aerobic and anaerobic conditions. Despite these differences, bacterial classification models performed well under both cultivation modes. For anaerobic conditions, the stacked models achieved accuracies of 0.96 for Gram classification (distinguishing Gram-negative and Gram-positive bacteria) and 0.94 for the classification of five bacterial species. Under aerobic conditions, the models achieved accuracies of 0.98 for Gram classification and 0.86 for the classification of six bacterial species. Additionally, the characteristic metabolites of bacteria were identified and analyzed. SIGNIFICANCE: This study introduced a rapid, sensitive bacterial identification method using UVP-TOF MS-based volatolomics, achieving good classification accuracy through an innovative stacked algorithm. The direct clinical blood culture analysis had significant less-time consuming than traditional methods. Key advantages include superior species-level classification and clinically applicable automation, offering a significant improvement over conventional BSI diagnostics for timely therapeutic intervention.