Fibronectin: structure, functions, clinical significance (review)

Abstract

Plasma fibronectin is a high molecular weight adhesive glycoprotein. There are two types of fibronectin: plasma (soluble) and cellular derived (insoluble). Electron microscopy revealed two types of structural organization of fibronectin: compact and expanded. In solution, fibronectin has a compact conformation, and after binding to certain substrates (collagen, fibrin, heparin), it is expanded. Plasma fibronectin is one of the main opsonins of blood plasma in relation to the “targets” of phagocytosis of a predominantly non-bacterial nature, as well as to some types of bacteria. For the treatment of septic processes, as well as respiratory distress syndrome of adults with severe fibronectin deficiency, plasma cryoprecipitate is used – a donor plasma preparation containing a large amount of plasma fibronectin (more than 2 mg/ml). It was proposed to replenish the level of fibronectin in patients with sepsis and other conditions that cause plasma fibronectin deficiency with the help of donor freshly frozen plasma. Transfusion of large volumes of freshly frozen plasma (up to 1000–1500 ml) to patients effectively eliminates the deficiency of plasma fibronectin. The concentration of plasma fibronectin in the blood significantly decreases after the addition of severe infectious processes to hematological diseases, as well as acute DIC syndrome. Extracorporeal methods of blood purification – selective plasmapheresis – have been developed to correct immunocomplex and fibronectin-complex pathology. Two variants of selective plasmapheresis have been proposed: the method of heparinocryoprecipitation of plasma proteins and the method of heparinocryofractionation. In 1987, a plasma heparin precipitate was proposed as a source of fibronectin for the treatment of patients with trophic skin lesions. In 1992, a new method was proposed for obtaining blood preparations with a high concentration of plasma fibronectin from patients themselves (heparin cryofractionation). Autofibronectin preparations obtained by such methods are effective in the local treatment of trophic ulcers in 90–93% of cases. The proposed drugs are safe against infection of patients with infectious diseases transmitted through the blood.

Keywords

• fibronectin
• opsonins
• selective plasmapheresis
• heparin cryoprecipitation
• heparin cryofractionation
• autofibronectin