Daily Ards Research Analysis
Immunometabolic modulation and precision phenotyping are prominent in today's ARDS research. A mechanistic study links IL-35 to Treg differentiation via JAK-STAT and glutamine/TCA rewiring, a post-hoc analysis implicates sRAGE and RALE trajectories as mediators of survival, and a large multicenter cohort associates lung-protective tidal volumes with lower ICU mortality in acute brain injury.
Summary
Immunometabolic modulation and precision phenotyping are prominent in today's ARDS research. A mechanistic study links IL-35 to Treg differentiation via JAK-STAT and glutamine/TCA rewiring, a post-hoc analysis implicates sRAGE and RALE trajectories as mediators of survival, and a large multicenter cohort associates lung-protective tidal volumes with lower ICU mortality in acute brain injury.
Research Themes
- Immunometabolism and Treg modulation in ARDS
- Biomarker- and imaging-driven precision medicine
- Lung-protective ventilation strategies across neurologic critical care
Selected Articles
1. Interleukin-35 regulates the differentiation of regulatory T cells through the JAK-STAT pathway and influences glutamine metabolism in ARDS.
Using clinical samples, a sepsis-induced lung injury model, and multi-omic assays, the authors show that IL-35 reduces lung inflammation, promotes Treg differentiation, and rewires glutamine/TCA metabolism in ARDS models via JAK-STAT signaling. Pharmacologic JAK/STAT inhibition with cerdulatinib reversed IL-35–induced Foxp3 upregulation and metabolic changes, implicating STAT phosphorylation as a mediator.
Impact: This mechanistic study links an immunoregulatory cytokine to Treg differentiation and immunometabolism in ARDS, suggesting a druggable JAK-STAT axis. It advances understanding of ARDS immunometabolic reprogramming and identifies IL-35 as a potential therapeutic modulator.
Clinical Implications: Findings support exploration of IL-35–based or JAK-STAT–targeted immunometabolic therapies in ARDS, with attention to patient selection and metabolic phenotypes.
Key Findings
- IL-35 decreased inflammatory mediators and increased Foxp3 expression, promoting Treg differentiation.
- IL-35 altered glutamine metabolites and TCA cycle intermediates, indicating immunometabolic rewiring.
- IL-35 increased phosphorylation of STAT isoforms; the JAK/SYK inhibitor cerdulatinib reversed these effects.
- In a CLP-induced lung injury model, IL-35 reduced lung inflammation; effects on Foxp3 and metabolism were abrogated by cerdulatinib.
Methodological Strengths
- Multi-system validation (clinical samples, in vivo sepsis model, and cell-based assays).
- Orthogonal methods including flow cytometry, IHC, qRT-PCR, LC-MS metabolomics, and targeted pathway inhibition.
Limitations
- Translational gap: preclinical models and limited clinical sampling without trial-level outcomes.
- Potential off-target effects of cerdulatinib and reliance on A549/EL-4 systems.
Future Directions: Test IL-35/JAK-STAT modulation in ARDS-relevant translational models and early-phase trials; integrate metabolic phenotyping and genetic perturbation (e.g., STAT/Foxp3) to confirm causality.
The aim of this study was to elucidate the effect of interleukin (IL)-35 on T-cell differentiation and its mechanism. We evaluated the therapeutic effect of IL-35 on acute respiratory distress syndrome using clinical samples and the mouse cecum ligation and puncture model. The effects of IL-35 on regulatory T cells (Tregs) were verified by flow cytometry, immunohistochemistry, and quantitative real-time reverse transcription polymerase chain reaction. Liquid chromatography-mass spectrometry was used to detect the effects of IL-35 on changes in glutamine metabolites and tricarboxylic acid (TCA) circulation. Western blot was used to detect changes in forkhead box protein 3 (Foxp3), key enzymes, and signal transducer and activator of transcription (STAT) phosphorylation subgroup proteins in the presence of cerdulatinib. Finally, A549 cells were treated with EL-4 cell supernatant to explore the effect of cerdulatinib on the therapeutic effect of IL-35 injury. Inflammatory factors decreased, and Foxp3 increased in response to IL-35. In addition, Foxp3 was upregulated in a glutamine-deficient environment, and notably, glutamine-related metabolism and TCA cycle-related substances were altered with the involvement of IL-35. IL-35 upregulated phosphorylation of STAT isoforms, and cerdulatinib reversed it. Finally, the effects of IL-35 on Foxp3, key enzymes, and glutamine metabolite changes were all reversed by cerdulatinib. Our study shows that IL-35 reduces lung inflammation and promotes Treg differentiation. IL-35 affects the glutamine metabolism and the TCA cycle. In addition, we demonstrated that the relevant functions of IL-35 may be mediated by STAT isoform phosphorylation.
2. Low-Tidal-Volume Ventilation and Mortality in Patients With Acute Brain Injury: A Secondary Analysis of an International Observational Study.
In 1,510 mechanically ventilated ABI patients from 73 ICUs in 18 countries, LTVV (≤8 mL/kg PBW) over the first 7 days was associated with lower ICU mortality up to 60 days versus higher tidal volumes (mHR 0.54, 95% CI 0.33–0.88). Effects were consistent across subgroups; associations diminished at lower LTVV thresholds.
Impact: Extends lung-protective ventilation principles beyond ARDS to ABI, using robust causal methods in a large international cohort.
Clinical Implications: Supports prioritizing lung-protective tidal volumes in ABI while awaiting RCTs, with careful monitoring for neurophysiologic effects and consideration of ARDS risk.
Key Findings
- Among 1,510 ABI patients, LTVV (≤8 mL/kg PBW) was associated with lower ICU mortality up to 60 days (mHR 0.54, 95% CI 0.33–0.88).
- No heterogeneity of treatment effect across subgroups; sensitivity analyses for unmeasured confounding were consistent.
- Associations were less clear when applying lower LTVV thresholds.
- ARDS occurred in 9.2% of patients, suggesting potential overlap populations for lung-protective strategies.
Methodological Strengths
- Prospective, multinational cohort with 73 ICUs across 18 countries.
- Marginal structural Cox models with stabilized IPTW adjusting for baseline and time-varying confounders; registered study (NCT03400904).
Limitations
- Observational secondary analysis with potential residual confounding and indication bias.
- Functional outcomes and neuro-specific adverse events were not primary endpoints; predominantly non-ARDS population.
Future Directions: Conduct RCTs of LTVV in ABI (including ABI+ARDS), evaluate lower tidal volume thresholds, and incorporate neurologic outcomes and ICP dynamics.
BACKGROUND: Low-tidal-volume ventilation (LTVV) improves outcomes in critically ill patients, but its impact in patients with acute brain injuries (ABIs) is less certain. RESEARCH QUESTION: What is the association between LTVV and mortality in mechanically ventilated patients with ABI? STUDY DESIGN AND METHODS: We did a secondary analysis of a prospective observational study (NCT03400904; https://clinicaltrials.gov/study/NCT03400904). We compared LTVV (≤ 8 mL/kg predicted body weight [PBW]) with tidal volumes > 8 mL/kg PBW over the first 7 days of mechanical ventilation. Alternate analyses used lower thresholds for LTVV. Marginal structural Cox models were used to evaluate the association between LTVV and ICU mortality up to 60 days. Stabilized inverse probability treatment and censoring weights were generated using multivariable logistic regression adjusted for baseline and time-dependent confounders. RESULTS: A total of 1,510 patients from 73 ICUs across 18 countries were included. The mean age was 52 years, 513 patients (34.0%) were female, and the most common ABI etiology was traumatic brain injury (n = 726; 48.1%). ARDS developed in 137 patients (9.2%). In patients receiving LTVV, adjusted incidence of ICU mortality was 40.2% (95% CI, 19.2%-61.1%), vs 59.7% (95% CI, 44.0%-75.4%) in patients receiving tidal volumes > 8 mL/kg PBW (marginal hazard ratio, 0.54; 95% CI, 0.33-0.88). There was no heterogeneity of treatment effect in subgroup analyses, and sensitivity analyses for unmeasured confounding yielded similar results. However, associations were less clear at lower thresholds of LTVV. INTERPRETATION: In this predominantly non-ARDS cohort of patients with ABI, LTVV over the first 7 days of mechanical ventilation was associated with lower ICU mortality up to 60 days, vs tidal volumes > 8 mL/kg PBW. Future research should investigate effects in patients with ABI and ARDS, use of lower LTVV thresholds, and impact on additional end points including functional outcomes and adverse events.
3. Post-hoc mediation analysis of two biomarkers, and survival in acute respiratory distress syndrome.
In a secondary analysis of the LIVE trial (n=115 analyzed), group-based trajectories of sRAGE and RALE were identified and shown to mediate the relationship between ventilator strategy and 90-day survival in opposing directions for specific clusters. These findings support using biomarker and imaging trajectories as surrogate endpoints in precision ARDS trials.
Impact: Introduces a causal framework linking biomarker and imaging trajectories to survival, advancing precision phenotyping and surrogate endpoint development in ARDS.
Clinical Implications: Supports stratifying ARDS patients by sRAGE/RALE trajectory clusters for tailored ventilator strategies and trial enrichment.
Key Findings
- Three trajectory groups were identified for both sRAGE and RALE among 115 ARDS patients from the LIVE trial.
- Ventilator strategy influenced survival directly and indirectly via RALE (aligned with the direct effect) and sRAGE (opposing direction) trajectories.
- Biomarker and imaging trajectories mediated survival for specific patient clusters, supporting surrogate endpoint use in precision ARDS trials.
Methodological Strengths
- Causal mediation analysis with group-based trajectory modeling to capture longitudinal biomarker patterns.
- Use of data from a randomized trial (LIVE), enhancing internal validity of exposure definition.
Limitations
- Secondary, post-hoc analysis with a modest sample size (n=115) and potential selection bias.
- Findings are cluster-specific and hypothesis-generating; generalizability and measurement timing require validation.
Future Directions: Prospectively validate sRAGE/RALE trajectory clusters, embed them as stratification or surrogate endpoints in adaptive ARDS trials, and test trajectory-guided ventilator strategies.
Previous studies have shown that plasma soluble receptor for advanced glycation end-products (sRAGE) and the radiographic assessment of lung edema (RALE) are associated with the severity of acute respiratory distress syndrome (ARDS) both at baseline and over time. This study aims to explore the causal relationships among sRAGE, the RALE score, their fluctuations, and 90-day survival. Causal mediation analysis was conducted as a secondary analysis of the randomized controlled lung imaging for ventilator setting in ARDS (LIVE) trial, which assessed a mechanical ventilation strategy based on lung morphology. The primary outcome was survival at day 90. We used group-based trajectory modeling to summarize the biomarker patterns over time, followed by mediation analysis with the sRAGE and RALE score as mediators. Out of 400 patients in the LIVE study, 115 were included, resulting in three trajectory groups for both sRAGE and RALE. The mechanical ventilation strategy appeared to influence survival directly and indirectly: one indirect effect was mediated by one RALE score trajectory (aligning with the direct effect), and another by one sRAGE trajectory (opposing the direct effect). Both plasma sRAGE and the RALE score appeared to exhibit a mediation effect on survival for specific patient clusters. Identifying these clusters and using biomarkers as surrogate endpoints warrants further investigation in precision ARDS trials.