What are glycocalyx?

From the Guidelines

Glycocalyx are a gel-like component that covers the surface of the vascular lumen, exhibiting antithrombotic, anti-inflammatory, and regulatory functions of vascular permeability 1.

Key Characteristics of Glycocalyx

• The glycocalyx is vulnerable to degradation by various inflammatory mediators, such as heparanase, matrix metalloproteases, and reactive oxygen species 1.
• Syndecans, membrane-bound proteoglycans, are key components of the glycocalyx and have been investigated as potential biomarkers for endothelial injury 1.
• The levels of glycocalyx components, including hyaluronic acid and heparan sulfate, have been examined in various diseases and correlated with the severity of diseases 1.
• The glycocalyx plays a critical role in regulating cellular interactions in thromboinflammation, and its dysfunction is associated with endothelial injury and coagulopathy 1.

Clinical Significance of Glycocalyx

• The glycocalyx is important for maintaining endothelial function and preventing coagulation and inflammation 1.
• Endothelial dysfunction, characterized by glycocalyx degradation, is a key component of disseminated intravascular coagulation (DIC) and is associated with increased morbidity and mortality 1.
• Antithrombin activity, which is affected by glycocalyx degradation, is a potential biomarker for endothelial dysfunction and has been associated with patient outcomes in sepsis and DIC 1.

From the Research

Definition and Composition of Glycocalyx

• The glycocalyx is a dynamic network of multiple membrane-bound complexes lining the vascular endothelium 2
• It is a layer composed of glycosaminoglycans, proteoglycans, and glycoproteins attached to the vascular endothelial luminal surface 3
• The glycocalyx is comprised of membrane-attached proteoglycans, glycosaminoglycan chains, glycoproteins, and adherent plasma proteins 4
• It is a gel-like layer covering the luminal surface of vascular endothelial cells 4

Functions of Glycocalyx

• The glycocalyx maintains homeostasis of the vasculature, including controlling vascular permeability and microvascular tone, preventing microvascular thrombosis, and regulating leukocyte adhesion 4
• It regulates vascular permeability as well as a range of vital functions, such as mechanotransduction, hemostasis, modulation of inflammatory processes, and serving as an antiatherogenic 2
• The glycocalyx has several physiological roles: shear stress mechanotransduction to the endothelial cells, regulation of fluids and macromolecules vascular permeability, of coagulation cascade activation and fibrinolysis, and protects the endothelium from platelets and leukocytes adhesion 3

Damage to Glycocalyx

• The glycocalyx may be damaged by abnormal shear stress, reactive oxygen species, hypernatremia, hyperglycemia, hypercholesterolemia, and inflammatory molecules, resulting in endothelial dysfunction, enhanced vascular permeability, lipoproteins leakage to subendothelial space, activation of plasma coagulation, and increased adherence of platelets and leukocytes to the endothelial cells 3
• During sepsis, the glycocalyx is degraded via inflammatory mechanisms such as metalloproteinases, heparanase, and hyaluronidase 4
• Glycocalyx damage can be caused by hypervolaemia and hyperglycaemia and can be prevented by maintaining a physiological concentration of plasma protein, particularly albumin 5