Daily Sepsis Research Analysis
Analyzed 11 papers and selected 3 impactful papers.
Summary
Three studies collectively advance our understanding of sepsis susceptibility and potential interventions across microbiome, metabolic comorbidity, and RNA therapeutics. A Cell Host & Microbe paper links early antibiotics, gut microbiota immaturity, and a DL-endopeptidase deficiency to preterm late-onset sepsis with mechanistic NOD2/MDP signaling and a pilot RCT of L. reuteri. Mechanistic studies show hyperglycemia-driven macrophage pathology can be mitigated via lncRNA Gm16023 delivery, and type 2 diabetes impairs macrophage phagocytic function that is partially restored by GM-CSF in mice.
Research Themes
- Microbiome-mediated susceptibility and prevention of sepsis in preterm infants
- Metabolic comorbidity (type 2 diabetes, hyperglycemia) impairing innate immunity in sepsis
- RNA-based and immunomodulatory therapeutic strategies targeting macrophage dysfunction
Selected Articles
1. Gut microbiota immaturity with DL-endopeptidase deficiency links antibiotic use to preterm late-onset sepsis.
Across multi-country preterm cohorts, delayed gut microbiota maturation—marked by loss of a bacterial DL-endopeptidase—mediated a substantial portion of antibiotic-associated LOS risk. Mechanistic work showed DL-endopeptidase-producing probiotics activate NOD2 via MDP, modulate macrophages via CYLD, and protect neonatal mice; a pilot RCT indicated L. reuteri enhances fecal NOD2 activation in preterm infants.
Impact: This study integrates large longitudinal human cohorts, mechanistic mouse experiments, and a pilot RCT to identify a modifiable microbial enzymatic pathway (DL-endopeptidase/NOD2) linking antibiotics to LOS. It proposes a biomarker and rational strain selection for targeted probiotic prevention.
Clinical Implications: In NICUs, selecting or developing probiotics with DL-endopeptidase activity could be prioritized for LOS prevention, and fecal NOD2 activation may serve as a pharmacodynamic biomarker. Findings also support cautious antibiotic use to avoid microbiota immaturity.
Key Findings
- In 4,938 longitudinal fecal samples, delayed microbiota maturation explained over one-third of early-antibiotic-associated LOS risk in preterm infants.
- Deficiency of a bacterial DL-endopeptidase marked immature microbiota and correlated with higher LOS risk.
- DL-endopeptidase-producing E. faecium or L. reuteri activated NOD2 via MDP, induced CYLD, modulated macrophage polarization, and protected neonatal mice from LOS.
- A pilot randomized trial showed L. reuteri increased fecal NOD2 activation in preterm infants.
Methodological Strengths
- Multi-country longitudinal cohorts with mechanistic validation across in vitro and in vivo systems
- Human pilot randomized trial providing translational biomarker evidence (fecal NOD2 activation)
Limitations
- Pilot RCT was small and focused on biomarker activation, not powered for clinical LOS outcomes.
- Causality and generalizability of specific strains and enzyme activity require larger, controlled clinical trials.
Future Directions: Conduct adequately powered RCTs testing DL-endopeptidase-producing probiotics on LOS incidence, validate fecal NOD2 activation as a surrogate, and develop rapid assays for DL-endopeptidase activity to guide NICU probiotic selection.
Early antibiotic exposure increases late-onset sepsis (LOS) risk in preterm infants, potentially via gut dysbiosis. Analyzing 4,938 longitudinal fecal samples from preterm infants in China, the US, and the UK, we identified a differential pace of gut microbiota development among preterm infants. Delayed maturation correlated with over one-third of LOS risk associated with early antibiotic exposure. Deficiency of a bacterial DL-endopeptidase represented a hallmark of delayed microbiota development and correlated with elevated LOS risk. Supplementation with DL-endopeptidase-producing Enterococcus faecium or Limosilactobacillus reuteri activated the NOD2 receptor via muramyl dipeptide (MDP), regulated macrophage differentiation and polarization, restrained hyperinflammation via cylindromatosis (CYLD) induction, and protected neonatal mice from LOS. A pilot randomized controlled trial showed that L. reuteri supplementation enhanced fecal NOD2 activation in preterm infants. These findings link microbiota immaturity and reduced DL-endopeptidase activity to antibiotic exposure and LOS risk and highlight a candidate biomarker that warrants further validation for clinical translation.
2. LncRNA Gm16023 ameliorates hyperglycemia-exacerbated septic intestinal injury by modulating macrophage polarization via miR-377-3p/Sirt1 axis.
UK Biobank data link hyperglycemia to higher sepsis risk. Mechanistic experiments identify a Gm16023/miR-377-3p/Sirt1 axis driving macrophage-mediated intestinal injury, with LNP-based Gm16023 delivery protecting against injury in models, suggesting an RNA-therapeutic avenue for diabetic sepsis.
Impact: This work connects population-scale epidemiology with mechanistic clarity and a deliverable RNA therapeutic, advancing a tractable targetable pathway for a high-risk subgroup (hyperglycemia in sepsis).
Clinical Implications: Supports glucose control and macrophage-targeted strategies in septic patients with hyperglycemia; LNP-based lncRNA modulation is promising but requires safety and efficacy testing in humans.
Key Findings
- Among 404,184 UK Biobank participants, hyperglycemia was significantly associated with increased sepsis risk.
- Hyperglycemia increased macrophage infiltration and intestinal inflammation in patients and mice; macrophage depletion reduced injury.
- Underexpressed lncRNA Gm16023 acts as a ceRNA regulating Sirt1 via miR-377-3p to inhibit M1 macrophage polarization.
- Lipid nanoparticle–encapsulated Gm16023 delivery protected against septic intestinal injury in vitro and in vivo.
Methodological Strengths
- Integration of large-scale epidemiology with genetic and pharmacologic macrophage depletion models
- Therapeutic delivery proof-of-concept using lipid nanoparticles across in vitro and in vivo systems
Limitations
- Translational relevance of mouse lncRNA Gm16023 to human orthologs and tissues remains to be established.
- No human interventional data; safety, dosing, and biodistribution of LNP-lncRNA require clinical evaluation.
Future Directions: Map human orthologous lncRNA pathways in septic gut, optimize LNP formulations for intestinal targeting, and design early-phase clinical studies in hyperglycemic septic patients.
Diabetes is closely associated with inflammation and sepsis, but its clinical significance and underlying mechanisms remain obscure. Leveraging epidemiological data from 404,184 individuals in the UK Biobank cohort, we found that hyperglycemia was significantly associated with increased sepsis risk. Phenotypically, hyperglycemia enhanced macrophage infiltration and exacerbated intestinal inflammation in both septic patients and murine models. Using both a genetic CD11b-DTR model and clodronate liposome (Cls)-mediated chemical ablation, we demonstrated that macrophage depletion markedly attenuated hyperglycemia-driven septic intestinal injury, underscoring their essential pathogenic role. Mechanistically, RNA sequencing analysis identified that underexpressed lncRNA Gm16023 acted as a ceRNA, binding miR-377-3p to regulate Sirt1 expression and inhibit M1 macrophage polarization. To facilitate therapeutic delivery, we engineered a lipid nanoparticle (LNP)-encapsulated Gm16023 plasmid system that efficiently delivered lncRNA in vivo and conferred protection against intestinal injury in both in vitro and in vivo models. Collectively, our findings indicate that hyperglycemia promotes macrophage-mediated septic intestinal injury via the lncRNA Gm16023/miR-377-3p/Sirt1 axis, highlighting a potential RNA-based therapeutic strategy for diabetic sepsis.
3. Type 2 diabetes impairs macrophage antimicrobial capability and increases susceptibility to sepsis.
T2D diminishes macrophage phagocytosis and intracellular killing via reduced phagocytic receptor expression and ROS generation, leading to higher bacterial burden and sepsis susceptibility in mice, with supportive findings in human T2D monocytes. GM-CSF restored macrophage function and improved survival in T2D septic mice.
Impact: This study mechanistically links a common comorbidity (T2D) to innate immune failure in sepsis and identifies GM-CSF as a potential immunorestorative strategy, with cross-species evidence.
Clinical Implications: Supports immune phenotyping in septic patients with T2D and motivates trials of GM-CSF or similar immunostimulants in carefully selected subgroups, alongside optimization of glycemic control.
Key Findings
- In T2D sepsis mouse models, macrophage phagocytosis and intracellular bacterial killing were significantly impaired, with increased bacterial burden and fewer tissue-resident macrophages.
- Peripheral monocytes from T2D patients and peritoneal macrophages from T2D mice showed reduced phagocytic receptor expression and diminished ROS generation.
- Exogenous GM-CSF restored macrophage/monocyte phagocytosis and bacterial clearance, improving survival and lowering bacterial loads in T2D septic mice.
Methodological Strengths
- Cross-species validation with human T2D monocytes and mouse CLP sepsis models
- Functional rescue experiments using GM-CSF establishing reversibility of defects
Limitations
- Preclinical models (CLP mice) may not fully recapitulate human T2D sepsis heterogeneity.
- Human data are observational; optimal dosing, timing, and safety of GM-CSF in T2D septic patients remain untested.
Future Directions: Design biomarker-driven phase II trials of GM-CSF in septic patients with T2D, incorporating macrophage functional readouts and glycemic stratification.
Sepsis remains one of the primary causes of mortality in intensive care units, with an overall death rate of approximately 20%. Type 2 diabetes (T2D) exacerbates the incidence of infections, leading to increased long-term morbidity and mortality associated with sepsis. Macrophages are critical for the defense and clearance of invading pathogens during sepsis. Nevertheless, limited research has addressed the impact of T2D on macrophage dysfunction in sepsis conditions. In this study, we observed a significant impairment in the phagocytic and intracellular bacterial killing abilities of macrophages in a T2D sepsis model. Utilizing the cecal ligation and puncture sepsis model, we revealed a reduction in tissue-resident macrophages and an elevated bacterial burden in T2D mice. Moreover, peripheral monocytes from T2D patients and peritoneal macrophages from T2D mice exhibited the dampened phagocytic and intracellular killing abilities, characterized by decreased expressions of phagocytic receptors and a diminished capacity to generate reactive oxygen species. In addition, exogenous granulocyte-macrophage colony-stimulating factor administration enhanced survival rates and reduced bacterial loads in T2D mice by restoring phagocytosis and bacterial eradication of macrophages/monocytes. Collectively, these data suggest that T2D contributes to macrophage dysfunction and impaired bacterial clearance, leading to an increased susceptibility to sepsis.