Daily Sepsis Research Analysis
New mechanistic work links sepsis to long-lasting bone marrow changes that blunt plasmacytoid dendritic cell reconstitution via TCF4 downregulation and G-CSF, illuminating a pathway for post-sepsis immunosuppression. Population data from Finland quantify the clinical and economic burden of invasive pneumococcal disease and highlight the preventive potential of higher-valent conjugate vaccines. In geriatric septic shock, REMS outperforms RAPS for 30-day mortality discrimination, supporting practi
Summary
New mechanistic work links sepsis to long-lasting bone marrow changes that blunt plasmacytoid dendritic cell reconstitution via TCF4 downregulation and G-CSF, illuminating a pathway for post-sepsis immunosuppression. Population data from Finland quantify the clinical and economic burden of invasive pneumococcal disease and highlight the preventive potential of higher-valent conjugate vaccines. In geriatric septic shock, REMS outperforms RAPS for 30-day mortality discrimination, supporting practical risk stratification in the ED.
Research Themes
- Sepsis-induced immunosuppression and hematopoietic dysregulation
- Population burden and vaccination strategies for invasive pneumococcal disease
- Risk stratification tools in geriatric septic shock
Selected Articles
1. Sepsis impairs immunocompetent plasmacytoid dendritic cell reconstitution from hematopoietic stem/progenitor cell through altered bone marrow environment.
Using CLP-induced sepsis in mice, the authors show that both pDCs and their progenitors are depleted and functionally skewed, with impaired type I IFN production and antigen presentation. CLP-derived HSPCs fail to generate immunocompetent pDCs due to downregulation of TCF4, which is reversible by ectopic TCF4 expression; elevated G-CSF replicates this impairment in vitro. These results identify a bone marrow niche–driven mechanism for post-sepsis immunosuppression.
Impact: This study uncovers a mechanistic link between elevated G-CSF, TCF4 downregulation, and defective pDC reconstitution after sepsis, offering concrete molecular targets to mitigate late immunosuppression.
Clinical Implications: Although preclinical, the data suggest that modulating the G-CSF–TCF4 axis or strategies to restore pDC competence could reduce post-sepsis susceptibility to viral and opportunistic infections, informing future translational studies.
Key Findings
- In CLP-induced sepsis, both pDCs and their progenitors are reduced and exhibit impaired type I IFN secretion and antigen presentation.
- HSPCs from CLP mice show reduced pDC output and lower IFN-α expression; TCF4 is downregulated during pDC differentiation.
- Ectopic TCF4 expression restores pDC generation; elevated bone marrow G-CSF and exogenous G-CSF impair immunocompetent pDC generation.
Methodological Strengths
- Combined in vivo CLP model with in vitro Flt3L-driven differentiation and functional assays
- Rescue experiments (TCF4 overexpression) and perturbation with G-CSF to test causality
Limitations
- Findings are from a murine model; human validation (bone marrow and peripheral pDCs) is lacking
- No in vivo infection challenge to link cellular defects to clinical susceptibility
Future Directions: Validate the G-CSF–TCF4–pDC axis in human sepsis cohorts, assess biomarkers of pDC competence, and test therapeutic modulation of TCF4 signaling or G-CSF blockade in translational models.
Plasmacytoid dendritic cells (pDCs) are crucial components of the immune response during viral infections, yet their function and development in the late phase of sepsis remain poorly understood. In this study, we investigated the impact of prolonged sepsis on pDCs and their progenitors in cecal ligation and puncture (CLP)-induced septic mice. We observed a significant reduction in both pDCs and their progenitors, alongside the presence of mature and regulatory pDCs. These mature and regulatory pDCs exhibited impaired type I interferon (IFN) secretion and antigen presentation capacity. In a Flt3L culture system of hematopoietic stem/progenitor cells (HSPCs) from CLP and Sham mice, we found that CLP-derived HSPCs exhibited an impaired ability to generate immunocompetent pDCs, as evidenced by lower IFN-α expression and reduced pDC recovery. Further investigation revealed downregulation of the key transcription factor TCF4 during pDC differentiation in these progenitor cells. Ectopic expression of TCF4 in these progenitors restored pDC generation. Additionally, we observed elevated levels of granulocyte colony-stimulating factor (G-CSF) in the bone marrow supernatant of septic mice. The addition of G-CSF to the culture system significantly impaired the generation of immunocompetent pDCs from HSPCs of normal mice. These findings suggest that sepsis may impair the production of immunocompetent pDCs from HSPCs by modulating key genes involved in pDC differentiation, potentially contributing to immune suppression and increased susceptibility to opportunistic infections in the later stages of sepsis.
2. Healthcare resource use and costs associated with episodes of laboratory confirmed invasive pneumococcal disease in adults in Finland 2016-2022.
In 4018 adult IPD episodes in Finland, 30-day case-fatality was 9.7% overall, rising to 26.7% in those ≥85 years. Average per-episode costs were €9118 (94% inpatient), with higher-valent conjugate vaccines (PCV20/PCV21) covering a greater share of serotypes in older adults than PCV13. These data quantify IPD’s burden and inform prevention policy.
Impact: Large, nationwide registry data provide precise estimates of mortality and costs for IPD, directly supporting vaccination and resource allocation decisions in populations at risk of sepsis.
Clinical Implications: Findings support broader adoption of higher-valent pneumococcal conjugate vaccines in older adults and underscore the inpatient cost burden of IPD, informing prevention and budgeting.
Key Findings
- Among 4018 adult IPD episodes, 30-day case-fatality was 9.7%, increasing from 3.2% (18–49 years) to 26.7% (≥85 years).
- Mean per-episode costs were €9118 (95% CI €8802–€9419), with 94% attributable to inpatient care; mean annual costs totaled €5.23 million.
- In adults ≥65 years, serotype coverage was 47.5% for PCV13, 66.5% for PCV20, and 77.0% for PCV21(V116).
Methodological Strengths
- Nationwide linked registries with large sample size and standardized costing
- Age-stratified outcomes and costs with confidence intervals
Limitations
- Retrospective observational design limits causal inference and control of confounding
- Generalizability may be limited outside Finland; vaccine effectiveness was not directly evaluated
Future Directions: Conduct cost-effectiveness analyses for PCV20/PCV21 in older adults, and evaluate patient-level predictors and sepsis-specific outcomes in IPD cohorts.
BACKGROUND: Streptococcus pneumoniae is a common mortality and morbidity causing pathogen worldwide which can lead to both invasive and noninvasive pneumococcal disease. Invasive pneumococcal disease (IPD) is a severe form of pneumococcal infection manifesting, for example, as bacteremia, sepsis, or meningitis. This study evaluated the clinical and economic burden caused by laboratory confirmed IPD in the population aged ≥18 years in Finland 2016-2022. METHODS: IPD episodes were identified from the National Infectious Disease Register. Healthcare resource use (HCRU) was obtained from the Finnish care registers and linked to each 90-day episode. Case-fatality was determined within 30 days since the first S. pneumoniae culture. HCRU, including hospitalizations and outpatient visits, was valued according to the national healthcare unit costs. The direct costs associated with HCRU, adjusted to the 2023 level, were calculated per episode and per year, and stratified by patient's age. RESULTS: Overall, 4018 IPD episodes were identified, with the median age of patients being 67 years. Meningitis was identified for 2.9 % of the episodes. Case-fatality was 9.7 % in all adults and increased steeply with age, from 3.2 % in 18-49-year-olds to 26.7 % in ≥85-year-olds. The average costs per episode were €9118 (95 % confidence interval [CI] €8802-€9419), with the highest costs (€9953; 95 % CI €9242-€10,562) observed in the 65-74-year-olds. In all adults, the mean total annual costs associated with IPD episodes were €5.23 million (95 % CI €3.66-€6.57 million). Inpatient care comprised 94 % of the total costs. In adults aged 65 and older, serotype coverage for pneumococcal conjugate vaccines PCV13, PCV20 and PCV21(V116) was 47.5 %, 66.5 %, 77.0 %, respectively. CONCLUSIONS: This study demonstrates the significant burden of IPD in the Finnish adult population. Wider vaccination against S. pneumoniae has the potential to substantially reduce the health and economic burden associated with pneumococcal diseases especially among older adults.
3. Evaluation of the rapid emergency medicine score and rapid acute physiology score scoring systems in predicting short-term survival outcomes in geriatric septic shock patients in the emergency department.
In 197 geriatric septic shock patients, 30-day mortality was 59%. REMS achieved an AUC of 0.705 versus 0.659 for RAPS (p=0.027), and both scores were independent mortality predictors in multivariable models. REMS offers modest but superior discrimination for short-term outcomes in this high-risk group.
Impact: Head-to-head prospective comparison supports selecting REMS over RAPS for ED risk stratification in geriatric septic shock, a population with very high mortality.
Clinical Implications: ED teams may preferentially use REMS to stratify 30-day mortality risk in geriatric septic shock, while recognizing its moderate AUC and the need for complementary clinical judgment.
Key Findings
- Among 197 geriatric septic shock patients, 30-day all-cause mortality was 59%.
- REMS had higher discrimination than RAPS (AUC 0.705 vs 0.659; DeLong p=0.027).
- Both REMS and RAPS were independent predictors of 30-day mortality in multivariable models.
Methodological Strengths
- Prospective design with head-to-head score comparison
- Appropriate statistical analyses (ROC/AUC, DeLong test, multivariable logistic regression)
Limitations
- Single-center and modest sample size limit generalizability
- Only two scores evaluated; calibration and external validation not reported
Future Directions: Validate REMS thresholds in multi-center cohorts, assess dynamic changes during resuscitation, and compare against newer sepsis-specific risk tools.
OBJECTIVE: To evaluate the ability of the Rapid Emergency Medicine Score (REMS) and the Rapid Acute Physiology Score (RAPS) to predict short-term survival among geriatric patients with septic shock. MATERIALS AND METHODS: This observational diagnostic validity study prospectively evaluated patients aged 65 years and older who presented to the emergency department with septic shock. Septic shock was defined as sepsis with persisting hypotension requiring vasopressors to maintain MAP ≥65 mmHg and having a serum lactate level > 2 mmol/L despite adequate volume resuscitation. The definition of sepsis was based on the Sepsis-3 guidelines. The patients were categorized into survivor and mortality groups based on their 30-day all-cause survival status. REMS and RAPS scores were calculated on admission, and their prognostic values were assessed using logistic regression and receiver operator characteristic analysis. RESULTS: A total of 197 patients were included in the study. The 30-day all-cause mortality rate was 59 %. The area under the curve value of REMS was calculated to be 0.705, while that of RAPS was 0.659. A pairwise comparison conducted using the DeLong test revealed that REMS had a statistically significantly higher discriminative power than RAPS (area under the curve difference: 0.046, 95 % confidence interval: 0.005-0.087, p = 0.027). According to the results of separate multivariate analyses performed for REMS and RAPS (Model 1 and Model 2), both scoring systems were independent predictors (p < 0.001 and p = 0.011, respectively). CONCLUSION: Our findings indicate that REMS has a statistically higher discrimination capacity compared to RAPS. However, both scoring systems have prognostic value in predicting mortality among the geriatric population.