Daily Ards Research Analysis
Three studies advance ARDS science across translational, mechanistic, and methodological fronts. Plasma extracellular vesicles in sepsis were shown to drive alveolar macrophage autophagy/ferroptosis via miR-223-3p–MEF2C/Hippo signaling and yielded biomarker candidates for septic ARDS. Complementing this, lung O-GlcNAcylation was found to protect against ischemia–reperfusion-induced ferroptosis via the Nrf2/G6PDH pathway, while a droplet microfluidic platform engineered ACE2 catalytic activity on
Summary
Three studies advance ARDS science across translational, mechanistic, and methodological fronts. Plasma extracellular vesicles in sepsis were shown to drive alveolar macrophage autophagy/ferroptosis via miR-223-3p–MEF2C/Hippo signaling and yielded biomarker candidates for septic ARDS. Complementing this, lung O-GlcNAcylation was found to protect against ischemia–reperfusion-induced ferroptosis via the Nrf2/G6PDH pathway, while a droplet microfluidic platform engineered ACE2 catalytic activity on native substrates, offering a tool for future ARDS-relevant therapeutics.
Research Themes
- Extracellular vesicles and miRNA-driven macrophage ferroptosis in septic ARDS
- Glycobiology and redox regulation: O-GlcNAcylation protecting lungs via Nrf2/G6PDH
- Ultra-high-throughput enzyme engineering on native substrates for ARDS-relevant therapeutics
Selected Articles
1. Plasma-derived extracellular vesicles prime alveolar macrophages for autophagy and ferroptosis in sepsis-induced acute lung injury.
Septic plasma EVs carry miRNA/protein cargo that correlates with disease severity and independently predicts septic ARDS, notably LCN2, miR-122-5p, and miR-223-3p. Mechanistically, miR-223-3p in EVs activates Hippo signaling via MEF2C targeting to induce autophagy and ferroptosis in alveolar macrophages; in vivo inhibition attenuated lung injury.
Impact: This study links circulating EV cargo to both predictive biomarkers and a causal pathway for lung injury in sepsis, bridging diagnostics and therapeutics. It provides tractable targets (miR-223-3p/MEF2C/Hippo) for intervention.
Clinical Implications: EV-derived miR-223-3p, miR-122-5p, and LCN2 could inform risk stratification for septic ARDS, while miR-223-3p inhibition or modulation of Hippo signaling in alveolar macrophages represents a potential therapeutic strategy.
Key Findings
- EV panels (miR-122-5p, miR-125b-5p, miR-223-3p, OLFM4, LCN2) associate with sepsis severity/prognosis with promising AUCs.
- LCN2, miR-122-5p, and miR-223-3p are independent predictors of septic ARDS.
- EV miR-223-3p activates Hippo signaling by targeting MEF2C, inducing autophagy and ferroptosis in alveolar macrophages; in vivo inhibition mitigates lung injury.
Methodological Strengths
- Integrated human EV miRNA/protein profiling with mechanistic in vitro and in vivo validation.
- Identification of independent predictors with reported AUCs, enhancing translational relevance.
Limitations
- Sample size and external validation cohorts are not specified in the abstract.
- Therapeutic targeting of EV pathways is preclinical; clinical efficacy remains untested.
Future Directions: Validate EV biomarker panels and thresholds in multicenter sepsis cohorts; develop miR-223-3p/Hippo-targeted interventions and delivery systems for ARDS.
Sepsis-induced acute respiratory distress syndrome (ARDS) is a severe complication of sepsis and the leading cause of mortality. Although the role of alveolar macrophages (AMs) in stabilizing pulmonary homeostasis is well established, the effects of circulating extracellular vesicles (EVs) on AMs remain largely unknown. In this study, an investigation was conducted to map the miRNA and protein expression profiles of EVs derived from septic plasma. Notably, EV-based panels (miR-122-5p, miR-125b-5p, miR-223-3p, OLFM4, and LCN2) have been found to be associated with the severity or prognosis of sepsis, with promising AUC values. Moreover, the levels of LCN2, miR-122-5p, and miR-223-3p were identified as independent predictors of septic ARDS. The in vitro coculture results revealed that the effects of LPS-EVs from the plasma of sepsis-induced acute lung injury (ALI), which carry pro-inflammatory EVs, were partly mediated by miR-223-3p, as evidenced by the promotion of inflammation, autophagy and ferroptosis in AMs. Mechanistically, the upregulation of miR-223-3p in LPS-EVs triggers autophagy and ferroptosis in AMs by activating Hippo signaling via the targeting of MEF2C. In vivo, the inhibition of miR-223-3p effectively mitigated LPS-EV-induced inflammation and AM death in the lungs, as well as histological lesions. Overall, miR-223-3p in LPS-EVs contributes to sepsis-induced ALI by priming AMs for autophagy and ferroptosis through the MEF2C/Hippo signaling pathway. These findings suggest a novel mechanism of plasma-AM interaction in sepsis-induced ALI, offering a plausible strategy for assessing septic progression and treating lung injury.
2. O-GlcNAcylation attenuates ischemia-reperfusion-induced pulmonary epithelial cell ferroptosis via the Nrf2/G6PDH pathway.
O-GlcNAcylation dynamically increases during lung I/R and limits epithelial ferroptosis via the Nrf2/G6PDH pathway. Ogt1 deficiency exacerbates ferroptosis markers in vivo, supporting O-GlcNAc-dependent cytoprotection in ALI/ARDS contexts.
Impact: Identifies a glyco-redox axis (O-GlcNAc–Nrf2/G6PDH) controlling ferroptosis in lung injury, offering a mechanistic basis for novel therapeutic strategies.
Clinical Implications: Targeting O-GlcNAc cycling or activating Nrf2/G6PDH may mitigate lung I/R injury and ALI/ARDS susceptibility to ferroptosis; pharmacologic modulators could be explored perioperatively (e.g., transplantation) or in shock states.
Key Findings
- Single-cell analyses in ALI/ARDS identified Ogt1 dysregulation and ferroptosis enrichment in epithelial cells.
- Lung O-GlcNAcylation changes dynamically during I/R; proteomics links to ferroptosis and redox pathways.
- Ogt1 conditional knockout aggravates ferroptosis markers in vivo; protection operates via Nrf2/G6PDH.
Methodological Strengths
- Multi-omics approach (single-cell transcriptomics, proteomics) integrated with conditional knockout mouse models.
- Mechanistic pathway mapping implicating Nrf2/G6PDH with in vivo readouts of ferroptosis.
Limitations
- Preclinical model; clinical validation and pharmacologic modulation of O-GlcNAc/Nrf2/G6PDH are not yet demonstrated.
- Focus on epithelial cells; contributions from other lung cell types require further study.
Future Directions: Test pharmacologic O-GlcNAc modulators and Nrf2/G6PDH activators in lung I/R and ARDS models; validate human tissue signatures and identify therapeutic windows.
BACKGROUND: Lung ischemia-reperfusion (I/R) injury is a common clinical pathology associated with high mortality. The pathophysiology of lung I/R injury involves ferroptosis and elevated protein O-GlcNAcylation levels, while the effect of O-GlcNAcylation on lung I/R injury remains unclear. This research aimed to explore the effect of O-GlcNAcylation on reducing ferroptosis in pulmonary epithelial cells caused by I/R. RESULTS: First, we identified O-GlcNAc transferase 1 (Ogt1) as a differentially expressed gene in lung epithelial cells of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients, using single-cell sequencing, and Gene Ontology analysis (GO analysis) revealed the enrichment of the ferroptosis process. We found a time-dependent dynamic alteration in lung O-GlcNAcylation during I/R injury. Proteomics analysis identified the differentially expressed proteins enriched in ferroptosis and multiple redox-related pathways based on KEGG annotation. Thus, we generated Ogt1-conditional knockout mice and found that Ogt1 deficiency aggravated ferroptosis, as evidenced by lipid reactive oxygen species (lipid ROS), malondialdehyde (MDA), Fe CONCLUSIONS: In summary, we revealed that O-GlcNAcylation could protect against I/R lung injury by reducing ferroptosis sensitivity via the Nrf2/G6PDH pathway. Our work will provide a new basis for clinical therapeutic strategies for pulmonary ischemia-reperfusion-induced acute lung injury.
3. Droplet microfluidic screening to engineer angiotensin-converting enzyme 2 (ACE2) catalytic activity.
A droplet microfluidic platform screens peptidases on native peptide substrates by detecting free amino acid release, enabling discovery of higher-activity ACE2 variants. The K187T ACE2 variant showed approximately 4-fold higher catalytic efficiency, demonstrating a route to engineer ACE2 for ARDS- and infection-relevant therapeutics.
Impact: Introduces an accessible, ultra-high-throughput method that avoids surrogate-substrate artifacts, with immediate utility for engineering therapeutic enzymes like ACE2.
Clinical Implications: Engineered ACE2 with enhanced catalytic efficiency could improve therapies aiming to rebalance the renin–angiotensin system in ARDS and viral lung disease; the platform generalizes to other peptidases for drug development.
Key Findings
- Developed a droplet microfluidic assay that quantifies native-substrate cleavage via free amino acid release.
- Identified ACE2 position 187 as an activity hotspot; K187T variant achieved ~4-fold higher catalytic efficiency.
- Demonstrated a scalable, accessible platform for therapeutic peptidase engineering.
Methodological Strengths
- Native-substrate, ultra-high-throughput screening reduces surrogate bias.
- Quantitative readout with free amino acid detection enables precise activity ranking across large libraries.
Limitations
- Preclinical engineering study; no in vivo efficacy or safety data for engineered ACE2 variants.
- Catalytic gains on selected substrates may not generalize across all physiologic targets.
Future Directions: Evaluate engineered ACE2 in relevant ARDS/viral infection models and optimize stability, specificity, and delivery; extend the platform to other therapeutic peptidases.
BACKGROUND: Angiotensin-Converting Enzyme 2 (ACE2) is a crucial peptidase in human peptide hormone signaling, catalyzing the conversion of Angiotensin-II to Angiotensin-(1-7), which activates the Mas receptor and elicits vasodilation, increased blood flow, reduced inflammation, and decreased pathological tissue remodeling. This study leverages protein engineering to enhance ACE2's therapeutic potential for treating conditions such as respiratory viral infections, acute respiratory distress syndrome, and diabetes. Surrogate substrates used in traditional high-throughput screening methods for peptidases often fail to accurately mimic native substrates, leading to less effective enzyme variants. Here, we developed an ultra-high-throughput droplet microfluidic platform to screen peptidases on native peptide substrates. Our assay detects substrate cleavage via free amino acid release, providing a precise measurement of biologically relevant peptidase activity. RESULTS: Using this new platform, we screened a large library of ACE2 variants, identifying position 187 as a hotspot for enhancing enzyme activity. Further focused screening revealed the K187T variant, which exhibited a fourfold increase in catalytic efficiency (k CONCLUSIONS: This work demonstrates the potential of droplet microfluidics for therapeutic peptidase engineering, offering a robust and accessible method to optimize enzyme properties for clinical applications.