Plasma Soluble Intercellular Adhesion Molecule-1 Has a Central Role in Biomarker Network Analysis and Is Associated With Poor Outcomes in Two Distinct Pediatric Cohorts of Acute Respiratory Distress Syndrome and Acute Respiratory Failure.

OBJECTIVES: Intercellular adhesion molecule-1 (ICAM-1) is a glycoprotein expressed on immune, endothelial, and epithelial cells. In the setting of inflammation, it becomes upregulated and spliced into a soluble form (soluble ICAM-1 [sICAM-1]). This study examined the association of sICAM-1 with clinical outcomes in two large pediatric cohorts with acute respiratory distress syndrome (ARDS) and acute respiratory failure (ARF) and examined the relationships between sICAM-1 and other protein biomarkers utilizing network analysis to contextualize its role in ARDS pathophysiology. DESIGN: Secondary analysis of prospective cohort studies. SETTING: Multicenter PICUs. PATIENTS OR SUBJECTS: Critically ill children with ARDS (Pediatric Acute Lung Injury [PALI], 2008-2014) and ARF (Coagulation and Fibrinolysis in Pediatric Insulin Titration Trial [CAF-PINT], 2012-2016). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: sICAM-1 levels were measured from plasma collected within 72 hours of diagnosis. The primary outcome was in-hospital mortality, and secondary outcomes included multiple organ dysfunction and ventilator-free days. We constructed a biomarker correlation-based network that included sICAM-1 and 32 plasma biomarkers reflective of inflammation, endothelial and epithelial injury, and extracellular matrix degradation. Key biomarkers with centrality metrics in the top 10% (≥ 90th percentile) were defined as critical hubs within the network. The study included 214 children from PALI and 251 from CAF-PINT. In-hospital mortality was 18% and 14%, respectively. Baseline median oxygenation index ratios were 10 (interquartile range [IQR], 5.6-19.7) and 8.5 (IQR, 3.5-17.7). Higher plasma sICAM-1 was associated with in-hospital mortality, multiple organ dysfunction, and fewer ventilator-free days in each of the two cohorts (all p < 0.05). Tissue inhibitor of metalloproteinase-1 (composite centrality, 0.99), tumor necrosis factor receptor-1 (0.83), sICAM-1 (0.74), and interleukin-8 (0.74) were identified as network hubs. CONCLUSIONS: Elevated sICAM-1 levels were associated with poor outcomes in two separate cohorts of ARDS and ARF patients. Network analysis revealed sICAM-1 as a central hub, characterized by high centrality metrics. These findings underscore the multifaceted role of sICAM-1 in leukocyte transmigration, inflammation, and endothelial dysfunction and highlight its critical role in ARDS pathophysiology.