Leukocyte actin cytoskeleton reorganization and redistribution of sialylated membrane glycoconjugates under experimental diabetes mellitus and against the administration of the Galega officinalis L. extract

Abstract

The article describes the effect of alkaloid-free fraction of the Galega officinalis extract (AFFGE) on the aggregation ability of immunocompetent blood cells, as well as on the process of actin polymerization and structural rearrangements among sialylated glycoconjugates of the peripheral blood leukocyte membranes of rats in the norm and under experimental diabetes mellitus (EDM) conditions. The flow cytometry method (using phalloidin labelled with fluorescent tetramethyl rhodamine-5-isothiocyanate (TRITC)) and the western blot analysis have allowed us to detect an increase in the rat leukocyte F-actin content in the event of diabetes mellitus, which indicated changes in the structural and functional properties of the leukocytes and their preactivation phase. A quantitative analysis of the total polymerized actin pool redistribution between its constituent fraction (represented by cytoskeletal filaments) and short actin filaments has shown that, against an increase in the total F-actin level, the number of actin filaments of the cytoskeleton decreased and the content of short actin filaments increased in leukocytes of animals with EDM. The use of sialylated lectins has allowed a conclusion to be made on the study of the pathology that the number of exposed oligosaccharide determinants on leukocyte membrane, the structure of which contained N-acetyl-β-D-glucosamine and sialic acid residues, increased, whereas the number of sialic acid-containing surface glycoconjugates bound to subterminal galactose residues by α2→3 and α2→6-glycoside bonds decreased. The administration of AFFGE to diabetic animals led to an increase in the content of F-actin and short filaments of the leukocyte cytoskeleton and a reduction in the lectin-induced leukocyte aggregation. The correction effect of the studied extract on the functional state of leukocytes can be realized through the action on the processes underlying the formation of the actin cytoskeletal elements and due to the quantitative redistribution of leukocyte membrane glycoconjugates with different structures of carbohydrate determinants, such as, due to a decrease in the exposure of N-acetyl-β-D-glucosamine residues and an increase in the exposure of sialic acids bound to subterminal galactose residues by α2→3 and α2→6-glycoside bonds.