Daily Ards Research Analysis

Critically ill patients with acute respiratory distress syndrome (ARDS) and sepsis exhibit distinct inflammatory phenotypes with divergent clinical outcomes and apparent heterogeneity of treatment effects, but the underlying molecular mechanisms remain poorly understood. These phenotypes, derived from clinical data and protein biomarkers, were associated with metabolic differences in a prior pilot study. This study investigated the metabolomic and transcriptomic differences between Hyperinflammatory and Hypoinflammatory phenotypes through integrative multi-omics analysis of blood samples from ARDS patients in the ROSE trial. Multi-omics integration revealed three molecular signatures strongly associated with the Hyperinflammatory phenotype and with mortality: enhanced innate immune activation coupled with increased glycolysis, hepatic dysfunction and immune dysfunction paired with impaired fatty acid beta-oxidation, and interferon program suppression coupled with altered mitochondrial respiration. A fourth molecular signature, not associated with inflammatory phenotype, identified redox impairment and cell proliferation pathways associated with mortality. Integrated multi-omics analysis within each inflammatory phenotype revealed distinct pathways associated with mortality. All mortality-associated molecular signatures including those within phenotypes were validated in an independent cohort of critically ill patients with sepsis (EARLI). These findings reveal distinct molecular mechanisms underlying ARDS/sepsis phenotypes and suggest potential therapeutic targets for precise treatment strategies in critical illness.

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterised by dysregulated inflammation, immune imbalance and impaired alveolar repair. Despite advances in supportive care, effective targeted therapies remain limited. Palmitoylation, a reversible lipid-based post-translational modification, has recently emerged as a regulatory mechanism in ARDS pathogenesis. Acting in a context-dependent manner, palmitoylation affects key processes, including immune activation, programmed cell death and epithelial remodelling. Accumulating evidence suggests that palmitoylation may exert dual roles in ARDS: it can promote inflammation and immune evasion in the early phase, while contributing to resolution and tissue repair during later stages. This review summarises current findings regarding the spatial and temporal regulation of palmitoylation in immune and structural cells involved in ARDS, including its effects on inflammasome activation, epithelial-immune interactions and fibrotic progression. Therapeutic approaches under investigation include selective inhibition of palmitoyltransferases (zinc finger aspartate-histidine-histidine-cysteine motif-containing-type palmitoyltransferase family), modulation of depalmitoylation enzymes and substrate-targeted strategies. Several preclinical studies support the feasibility of targeting palmitoylation to reduce lung injury and improve immune regulation. Overall, palmitoylation represents a potential regulatory node in ARDS pathophysiology. Further research is required to clarify its cell-specific functions and to assess the translational potential of palmitoylation-based interventions.

Critical illness initiates a cascade of systemic disturbances-including energy deficits, oxidative stress, endothelial injury, and intestinal barrier dysfunction. Mitochondria, the vascular endothelium, and the intestinal barrier are three critical interfaces that facilitate the restoration of homeostasis. These processes are regulated by the glucocorticoid (GC) signaling system, specifically through the glucocorticoid receptor α (GRα), which coordinates cellular metabolism, immune modulation, and vascular integrity. This integrated signaling network offers therapeutic targets to prevent or reduce organ dysfunction and damage. Mitochondria function as metabolic hubs, transforming substrates mobilized by GC-GRα into adenosine triphosphate (ATP) via oxidative phosphorylation (OXPHOS), while also regulating calcium homeostasis, reactive oxygen species (ROS) signaling, and apoptosis. However, excessive ROS generation during critical illness can disrupt cellular energetics, leading to systemic inflammation and critical illness-related corticosteroid insufficiency (CIRCI). GC-GRα signaling helps mitigate mitochondrial dysfunction by promoting mitochondrial biogenesis, enhancing antioxidant defenses, and maintaining redox balance, which is essential for metabolic recovery and survival. The vascular endothelium and the intestinal barrier are the two most extensive and vulnerable surfaces affected during critical illness, and their preservation or restoration is vital for recovery. These active interfaces are essential for maintaining vascular integrity, immune balance, and metabolic stability-functions that are often severely impaired in critical illness. The vascular endothelium, which lines the entire circulatory system, plays a crucial role in regulating vascular tone, permeability, and immune cell recruitment through mediators like nitric oxide and prostacyclin. In conditions such as sepsis and acute respiratory distress syndrome (ARDS), inflammatory injury damages the endothelial glycocalyx and tight junctions, leading to microvascular leakage and widespread inflammation. Activation of GC-GRα pathways helps restore endothelial integrity by inhibiting nuclear factor-κB (NF-κB), lowering proinflammatory cytokine production, increasing tight junction proteins, and boosting endothelial nitric oxide synthase (eNOS) activity-mechanisms that collectively prevent thrombosis and edema. The intestinal barrier, maintained by tight junctions and gut microbiota, is essential for nutrient absorption and mucosal immune defense. During critical illness, gut dysbiosis-marked by a depletion of beneficial commensals and overgrowth of pathogenic species-compromises barrier integrity, increases intestinal permeability, and promotes bacterial translocation. GC-GRα signaling plays a key role in preserving the intestinal barrier by regulating tight junctions, lowering permeability, and affecting microbiota composition. Combining GC therapy with microbiota-focused interventions offers hope for reducing inflammation, supporting recovery, and improving survival in critically ill patients.