Related Experiment Videos
Enhanced adhesion of oxidized mouse polymorphonuclear leukocytes to macrophages by a cell-surface sugar-dependent
M Beppu1, N Yokoyama, M Motohashi
1School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
Abstract:
Mouse thioglycollate-induced peritoneal macrophages effectively, in the absence of serum, recognized mouse polymorphonuclear leukocytes (PMNs) mildly oxidized with diamide, superoxide (hypoxanthine/xanthine oxidase) or t-butyhydroperoxide, or modified with N-ethylmaleimide (NEM). The recognition reached a maximum when PMNs were treated wtih each of the reagents at relatively low concentrations, and the recognition was decreased on treatment with reagents at higher concentrations. Glutathione depletion in the diamide-oxidized PMNs may cause enhanced adhesion to macrophages. Sialylated sugar chains attached to a peptide chain in glycophorin A and sialylated poly-N-acetyllactosaminyl sugar chains in lactoferrin and band 3 glycoprotein effectively inhibited the increased adhesion of the diamide-oxidized PMNs. Enzymatic removal of sialyl residues and the degradation of poly-N-acetyllactosaminyl sugar chains by pretreatment of PMNs with neuraminidase or endo-beta-galactosidase, respectively, lost their increasing ability for macrophage adhesion after oxidation with diamide, superoxide or t-butylhydroperoxide. Clustered sialylated poly-N-acetyllactosaminyl sugar chains on the cell surface may be involved in the increased adhesion of the oxidized PMNs to macrophages.
Insights
Macrophages recognize oxidized polymorphonuclear leukocytes (PMNs) through specific cell surface sugars. This interaction, crucial for immune response, is mediated by sialylated sugar chains on PMNs.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages play a critical role in clearing cellular debris and pathogens.
- Oxidative stress can alter cell surface properties, potentially affecting immune cell interactions.
Purpose of the Study:
- To investigate the molecular mechanisms by which macrophages recognize oxidized polymorphonuclear leukocytes (PMNs).
- To identify specific cell surface molecules on PMNs involved in their recognition by macrophages.
Main Methods:
- Thioglycollate-induced mouse peritoneal macrophages were used.
- Polymorphonuclear leukocytes (PMNs) were oxidized using diamide, superoxide, or t-butylhydroperoxide.
- Inhibition assays were performed using specific carbohydrate structures and enzymatic treatments (neuraminidase, endo-beta-galactosidase).
Main Results:
- Macrophages recognized oxidized PMNs in a serum-free environment.
- Recognition and adhesion were concentration-dependent on the oxidizing agents.
- Sialylated sugar chains, particularly poly-N-acetyllactosaminyl structures, inhibited PMN adhesion.
- Enzymatic removal of sialic acid or degradation of poly-N-acetyllactosaminyl chains abolished enhanced macrophage adhesion.
Conclusions:
- Clustered sialylated poly-N-acetyllactosaminyl sugar chains on the cell surface are involved in the increased adhesion of oxidized PMNs to macrophages.
- These findings elucidate a novel mechanism of immune cell recognition mediated by specific glycans under oxidative stress.