Daily Ards Research Analysis

BACKGROUND: Patients with sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) commonly suffer from severe pulmonary thrombosis, but clinical trials of anticoagulant therapies in patients with sepsis and ARDS have failed. Patients with ARDS with thrombocytopenia also exhibit increased mortality, and widespread pulmonary thrombosis is often seen in patients with COVID-19 ARDS. METHODS: Different amounts of microbeads were administered intravenously to adult mice to induce various levels of pulmonary thrombosis. ALI was induced by either intraperitoneal lipopolysaccharide or cecal ligation and puncture. Endothelial cell (EC)-targeted nanoparticles were used to deliver plasmid DNA expressing the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9) system for EC-specific gene knockout of Alox15 (arachidonate 15-lipoxygenase) or plasmid DNA expressing Alox15 for EC-specific overexpression. Lipidomic profiling and in vivo rescue studies with the identified Alox15-regulated lipids were performed. In addition, thrombocytopenia was induced by genetic depletion of platelets using RESULTS: We show that although severe pulmonary thrombosis or thrombocytopenia augments sepsis-induced ALI, the induction of mild pulmonary thrombosis conversely reduces EC apoptosis, ALI, and mortality via sustained expression of endothelial Alox15. Endothelial CONCLUSIONS: We have demonstrated that moderate levels of lung thrombosis protect against sepsis-induced inflammatory lung injury via endothelial Alox15. Overexpression of endothelial Alox15 inhibits severe pulmonary thrombosis-induced increases in ALI. Thus, upregulation of ALOX15 expression or treatment with ALOX15-dependent protective lipid(s) represents a promising therapeutic strategy for treatment of ARDS, especially in subpopulations of patients with thrombocytopenia and widespread pulmonary thrombosis.

BACKGROUND: In acute respiratory distress syndrome (ARDS), neutrophils, as the primary effector immune cells, undergo profound transcriptional and phenotypic reprogramming in response to complex inflammatory stimuli, modulating signal transduction and immune responses. Liquid-liquid phase separation (LLPS) plays a pivotal role in transcriptional dynamics and signal transduction, critically influencing gene expression stability. However, the mechanistic and clinical implications of LLPS in ARDS progression remain elusive. MATERIALS AND METHODS: This study systematically characterized neutrophil LLPS in ARDS through integrated single-cell transcriptomes (GSE157789), proteomes (GSE32707/GSE76293), and clinical cohorts date. LLPS-associated genes (LCGs) were screened from the PhaSepDB 2.1 database and subsequently integrated with single-cell sequencing data from Gene Expression Omnibus (GEO) to quantify neutrophil LLPS scores and divide patient stratification into high and low LLPS groups for differential expression analysis of critical LCGs and associated pathways. Phase-separated droplets were then isolated from peripheral blood neutrophils of ARDS patients and N-formylmethionyl-leucyl-phenylalanine (fMLP) -stimulated neutrophils, followed by proteomic identification of droplet-associated proteins and candidate gene selection through GEO data analysis. The prognostic value of LLPS scores and candidate genes was subsequently validated in clinical cohorts, while the relationship between phase separation of candidate genes and cellular function was experimentally confirmed through immunofluorescence, Western blotting, and complementary functional assays. RESULTS: Neutrophils in ARDS exhibit elevated LLPS scores ( CONCLUSIONS: This study demonstrates that LLPS dynamically regulates neutrophil migration through MYL12A phosphorylation-dependent phase separation, exerting immunoprotective effect in ARDS. The LLPS status of MYL12A and its activity score may serve as ARDS prognostic biomarkers and offer a novel strategy for developing LLPS-targeted immunomodulatory therapies.

INTRODUCTION: Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) have emerged as a promising cell-free therapeutic strategy for acute respiratory distress syndrome (ARDS), a condition with limited effective treatment options. METHODS: This systematic review synthesizes findings from 51 in vivo preclinical studies investigating the efficacy, delivery methods, mechanisms of action, and optimization strategies of MSC-EV interventions in experimental ARDS. RESULTS: Across diverse models and etiologies, MSC-EVs consistently attenuated inflammation, improved gas exchange, and enhanced survival. Mechanistically, these benefits were largely attributed to microRNA-mediated immunomodulation, including promotion of anti-inflammatory macrophage phenotypes and improved bacterial clearance. Factors influencing therapeutic efficacy included the MSC source, EV preconditioning, timing of administration, and route of delivery. DISCUSSION: Despite these encouraging findings, critical methodological heterogeneity limits reproducibility and translational potential. This heterogeneity is particularly evident in dose metrics (e.g., particle number versus protein content), EV quantification methods (e.g., flow cytometry versus nanoparticle tracking analysis), and timing of outcome assessment. This review underscores the growing body of preclinical evidence supporting MSC-EVs in ARDS and identifies key knowledge gaps such as optimal dosing, safety profiling, and scalable manufacturing that must be addressed to enable clinical translation.