Endothelial Glycocalyx biomarkers in acute lung injury

Endothelial glycocalyx (eGC) degradation contributes to vascular and pulmonary dysfunction in acute lung injury (ALI). This study provides a comprehensive review of the structure of the endothelial glycocalyx (eGC) and the mechanisms underlying its injury. Additionally, it evaluates biomarkers indicative of glycocalyx disruption that have been investigated for clinical use, including syndecan-1, heparan sulfate, and hyaluronan. These biomarkers have been studied in both circulating and airway compartments, with some studies reporting signal size-dependent variations in their levels. Laboratory measurement methods, specifically immunoassays and mass spectrometry, are examined with an emphasis on preanalytical variables, analytical performance, interference, and existing deficiencies in standardization, calibration, and traceability. These deficiencies contribute to the challenges in achieving comparability across different studies. Subsequently, we assessed the evidence regarding the clinical utility of risk stratification and outcome prediction in the context of ALI/ARDS and sepsis heterogeneity, focusing on cohort characteristics, sampling intervals, and sample types. In conclusion, we propose the implementation of novel glycocalyx-stabilizing treatments and future advancements, such as multi-marker panels and their integration with microvascular imaging. Generally, the standardization of protocols and establishment of reporting systems are essential prerequisites for the incorporation of these biomarkers into routine clinical laboratory and intensive care unit workflows as reliable tools.