The Role of Cytokines in Vascular Endothelial Glycocalyx Integrity and Impairment Following Open-Heart Surgery

Open-heart surgery with cardiopulmonary bypass (CPB) is a high-risk procedure with significant morbidity and mortality. CPB, tissue injury, blood loss, endotoxemia and ischemia-reperfusion injury induce a pronounced systemic inflammatory response, leading to endothelial glycocalyx (EG) damage and vascular endothelial dysfunction. Consequently, immune cells, reactive oxygen species, and enzymes gain free access to vascular endothelial cells, resulting in their dysfunction and enhancing inflammation, vascular permeability, and microvascular impairment. EG degradation is most commonly assessed by measuring the circulating levels of its degradation products. Additionally, CPB triggers an early inflammatory response that is characterized by the secretion of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor alpha, and IL-18, which play roles in initiating the process of EG injury. EG damage is further propagated by the sustained release of cytokines, inhibiting the regeneration of the glycocalyx layer. Heparanase and matrix metalloproteinases are enzymatic pathways involved in cytokine-mediated EG degradation after cardiac surgery, and the balance between the pro- and anti-inflammatory cytokines determines the magnitude and duration of the inflammatory response and EG impairment, which correlates with adverse clinical outcomes, including myocardial dysfunction, acute lung and kidney injury, neurological complications, and prolonged need for intensive care. Thus, identifying patients with an exaggerated cytokine response could potentially provide more personalized therapy based on the circulating biomarkers of EG shedding, and cytokine-directed preservation of EG represents a promising therapeutic strategy in vascular dysfunction prevention during and after open-heart surgery. In this review, we summarize the current knowledge on cytokine-mediated EG impairment following open-heart surgery with CPB.