Topo-optical investigations of the human erythrocyte glycocalyx-age related changes

Abstract

The conformational state of the glycocalyx of the intact and altered erythrocyte membrane was studied by means of the topo-optical toluidine blue reaction, i.e. induced membrane birefringence. High membrane anisotropy represents the normal glycocalyx structure and its decline represents their perturbation. The results show that the glycocalyx structure is changed during ageing of the erythrocytes in vivo as well as in vitro. During fluid preservation, in vitro ageing and vesiculation of cells in vitro, a subpopulation of cells showed a decline of membrane anisotropy, but other cells demonstrated abnormally high values. In the latter cases, there is usually a correlation to spherocytes. From this point of view, it is to be assumed that spherogenesis during cell ageing is induced by cell vesiculation. This leads to a remodelling of an intact plasmalemma. In contrast, the cell fractions which are probably non-vesiculating seem to be more or less damaged by membrane and/or plasmic hydrolases. This can be mimicked by neuraminidase and protease treatment of erythrocytes in vitro. Membrane lesions caused by freeze preservation of red blood cells are rare. The topo-optical results are interpreted according to the assumptions of the theory of membrane anisotropy, i.e. the formation of dye-stuff micelles at distinct, clustered, sialylated carbohydrate chains of the glycophorin A.

“Hairy Surface Layer” Concept of Electrophoresis Combined with Local Fixed Surface Charge Density Isotherms: Application to Human Erythrocyte Electrophoretic Fingerprinting

“…Important in this respect is the bimodal distribution of the sialic acid groups for the control. This is consistent with protein structure predictions suggesting sialic acid arangement in two layers. , It is also possible to explain the increase of the effective charge density upon an increase in ionic strength by a glycocalyx thickness change as a function of the salt concentration, resulting in a layer expansion upon a decrease in ionic strength . This is equivalent to a decrease of the absolute value of the spatial charge density.…”

Life‐threatening hemolytic anemia due to an autoanti‐Pr cold agglutinin: evidence that glycophorin A antibodies may induce lipid bilayer exposure and cation permeability independent of agglutination

“…In PE vesicles, hydrogen bonds between the COOH groups of sialic acid GPA and the amine groups of PE confers stability 32 . Likewise, in RBCs the external component of GPA lies close to the surface of the membrane and interacts with the phospholipid bilayer, an interaction that diminishes with the age of RBCs 33 …”

“…The hypothesis that glycosylated GPA has structurally important effects is supported by the observation that abnormal shape of spectrin‐deficient mouse RBCs was corrected by treatment with neuraminidase 34 . The loss of the sialic acid from RBCs 35‐38 both due to neuraminidase released by RBCs 39,40 and with aging in vivo 33 as well as with storage for transfusion 41 and increased Ca 2+ influx are well‐known properties of RBCs 42 . An age‐related loss of sialic acid from GPA could make some RBCs more susceptible to mechanical stress and accompanying Ca 2+ influx 12 .…”

“…32 Likewise, in RBCs the external component of GPA lies close to the surface of the membrane and interacts with the phospholipid bilayer, an interaction that diminishes with the age of RBCs. 33 The hypothesis that glycosylated GPA has structurally important effects is supported by the observation that abnormal shape of spectrin-deficient mouse RBCs was corrected by treatment with neuraminidase. 34 The loss of the sialic acid from RBCs [35][36][37][38] both due to neuraminidase released by RBCs 39,40 and with aging in vivo 33 as well as with storage for transfusion 41 and increased Ca 2+ influx are well-known properties of RBCs.…”

A Deadly Embrace: Hemagglutination Mediated by SARS-CoV-2 Spike Protein at Its 22 N-Glycosylation Sites, Red Blood Cell Surface Sialoglycoproteins, and Antibody

“…GPA molecules have the shapes of strands that are anchored approximately 14 nm apart on the RBC plasma membrane, each extending outwards 5 nm [ 75 ]. GPA constitutes the bulk of the RBC’s sialoglycoprotein coating, thus determining its 5 nm thickness [ 75 , 167 , 168 ], and accounts for most of its negative charge [ 31 , 169 ]. Electrostatic repulsion imposes a minimum distance of approximately 8 nm between the outer boundaries of those sialoglycoprotein coatings of adjoining RBCs in a static suspension, but a smaller separation can be achieved when additional forces are pushing these RBCs together [ 168 , 170 ].…”