Influence of intraperitoneal injection of three types of hydrogel beads on expression of carbohydrate-binding sites in spleen macrophages

Abstract

The influence of the chemical structure of polymer implants on selected characteristics of macrophages was studied to improve our understanding of the mechanisms of non-self recognition of synthetic materials. Three types of polymers differing in net charge were prepared to compare In vivo responses. Beads from preparations of poly(2-hydroxyethyl methacrylate), a copolymer of 2-hydroxyethyl methacrylate with sodium methacrylate, and a copolymer of 2-hydroxyethyl methacrylate and dimethylaminoethyl methacrylate were injected intraperitoneally into rats and harvested 48h later. The effects of these polymers on the presence of inflammatory cells in the peritoneal exudate, on the adhesion of macrophages to individual batches of the different types of beads and on distinct molecular aspects of macrophages in the red pulp of spleen were evaluated. Beads from both types of copolymer caused an elevation in the number of macrophages in the exudate, in contrast to the situation in rats treated with poly(2-hydroxyethyl methacrylate) beads and physiological saline solution as control. The molecular design of the implant had no significant influence on the extent of macrophage adhesion to beads or on the expression of selected carbohydrate-binding sites. Since important cellular functions such as cell adhesion and glycoprotein routing depend on the sugar part of glycoconjugates, labelled neoglycoproteins were employed to analyse this aspect of macrophages in the tested animals. The beads of the copolymer of 2-hydroxyethyl methacrylate with dimethylaminoethyl methacrylate clearly led to an elevation of the expression of specific binding sites for β-galactoside-terminating structures which are presented by asialofetuin, for mannose, fucose, sialic acid and N-acetylgalactosamine, which had been used as the ligand parts of biotinylated neoglycoproteins, in spleen macrophages, whereas the levels of sites which recognize mannose-6-phosphate were unaffected. Expression of sites with specificity to N-acetylglu-cosamine was lessened. The effect of beads from the copolymer of 2-hydroxyethyl methacrylate with sodium methacrylate on the measured glycobiological features in the splenic macrophages was only negligible. These results suggest the possibility of systemic effects of implanted polymers on the distinct recognitive functions of macrophages.