Neutrophil Gelatinase-Associated Lipocalin: A Shared Early Biomarker of Remote Organ Dysfunction in Blast-Induced Extremity Trauma.

Polytrauma is a critical global health concern characterized by immune dysregulation and a high risk of multiple organ dysfunction syndrome (MODS). Early molecular mechanisms linking trauma severity to organ injury are poorly understood. We used two rat blast-polytrauma models: a tourniquet-induced ischemia/reperfusion injury (tIRI) model and a non-ischemia/reperfusion injury (non-IRI) model. Naïve animals served as controls. RT-qPCR of 120 inflammatory genes in the lung, kidney, and liver, combined with STRING protein-protein interaction analysis, revealed distinct yet overlapping inflammatory gene signatures across all the organs. A core set of genes (Il6, Lbp, Nos2, and Lcn2) was consistently upregulated, indicating shared inflammatory pathways. Transcriptomic responses were most pronounced in the tIRI group, with greater magnitude and altered temporal dynamics, uniquely amplifying pro-inflammatory cytokines, immune cell activators, chemokines, and tissue damage markers. Lipocalin-2 (Lcn2/NGAL) emerged as a shared hub gene across all the organs within 24 h post-injury. Its expression significantly correlated with MODS activity and adverse outcomes, independent of the injury model. At 168 h, Lcn2 expression correlated with increased liver damage and NGAL levels correlated with tissue trauma severity. These findings elucidate distinct pro-inflammatory mediators and networks underlying secondary organ dysfunction, highlighting NGAL as a potential universal biomarker of trauma-induced inflammation and MODS activity, suggesting it as a therapeutic target.