Recombinant Human Interleukins IL-1α, IL-1β, IL-4, IL-6, and IL-7 Show Different and Specific Calcium-independent Carbohydrate-binding Properties

Abstract

A method was developed for the determination of putative lectin activities of cytokines. It involved the immunoblotting measurement of the quantity of these cytokines unbound to a series of different immobilized glycoconjugates and displacement of the bound cytokines with oligosaccharides of known structures. This method allows demonstrating that the following interleukins specifically recognize different oligosaccharide structures in a calcium-independent mechanism: interleukin-1␣ binds to the biantennary disialylated N-glycan completed with two Neu5Ac␣2-3 residues; interleukin-1␤ to a GM 4 sialylated glycolipid Neu5Ac␣2-3Gal␤1-Cer having very long and unusual long-chain bases; interleukin-4 to the 1,7 intramolecular lactone of N-acetyl-neuraminic acid; interleukin-6 to compounds having N-linked and O-linked HNK-1-like epitopes; and interleukin-7 to the sialyl-Tn antigen. Because the glycan ligands are rare structures in human circulating cells, it is suggested that such activities could be essential for providing specific signaling systems to cells having both the receptors and the oligosaccharide ligands of the interleukin at their cell surface.Cytokines are modulators of the activity of the immune system, their mechanism of action remaining, for the most part, not decrypted. As a general rule, the action of a cytokine results from its binding to membrane receptors, a series of molecules coupled to signaling systems involving kinases and/or phosphatases (1-5). The binding of a cytokine to its receptor(s) generally results in the phosphorylation/dephosphorylation of the intracytoplasmic domain of the receptor(s), the first step of the signaling. In general, the phosphorylation/dephosphorylation mechanism is cell type-specific, the kinases/phosphatases involved in these processes being quite specifically associated with surface molecular complexes different from the cytokine receptor complex (3, 6). Even when two different cytokines use the same receptor, the signal transduction pathways may be specific of the cytokines (7).We made the hypothesis that the specific association of interleukin receptors with other surface complexes could be due to carbohydrate-binding properties of these cytokines, a property already suggested in the literature (8 -14). The lectin activity of interleukin-2 (IL-2) 1 for specific oligomannosides (15) appeared to be essential, because IL-2 behaves as a bifunctional molecule able to extracellularly associate its ␤ receptor (IL-2R␤) to other surface receptor complexes bearing N-glycans recognized by IL-2. This is the case for the CD3⅐TCR complex in which a N-glycosylated form of CD3 is an IL-2 ligand. This specific extracellular association is responsible for the specific phosphorylation of the IL-2R␤ by the CD3⅐TCR-associated kinase p56 lck (15), considered as a first step in the antigenspecific activation process of CD4 ϩ T cells. As a consequence of this carbohydrate-binding property, it was suggested that oligomannosides accumulated in specific diseases or bound to specific microor...

Neuraminidase-1, a Subunit of the Cell Surface Elastin Receptor, Desialylates and Functionally Inactivates Adjacent Receptors Interacting with the Mitogenic Growth Factors PDGF-BB and IGF-2

“…The IL-1␤ was chosen because its receptor is not sialylated glycoprotein 68 and it can interact with the cell membrane GM4 sialylated glycolipid, Neu5Aca2-3Gal␤1-ceramide. 69 Thus, the detection of any diminution of the proliferative effects of IL-1␤ in cultures pretreated with C. perfringens Nase would indicate some collateral action of this enzyme (eg, through desialylation of cell membrane gangliosides) that might indirectly modify cellular proliferation. Then, we compared the magnitude of the proliferative effects of the same doses of PDGF-BB and IGF-2 in 3-day-old subconfluent cultures of normal human skin fibroblasts and Neu1-deficient fibroblasts derived from patients with congenital sialidosis.…”

Small Airways in Asthma: Distal is Different

“…There, it functions as first line of defense against airway infection and plays a major role in mucociliar clearance of the airways. Pathogens, particles and other chemicals are caught up in a mucus layer covering beating cilia, which constantly sweep the mucus from distal to proximal airways to finally force it out of the lung [22][23][24]. This mucus layer is composed of a low-viscosity and therefore low resistance liquid layer up to the height of the cilia supporting the cilia beating and an overlying high-viscosity gel layer [23,25,26].…”

Function and Molecular Modeling of the Interaction between Human Interleukin 6 and Its HNK-1 Oligosaccharide Ligands

“…These data did not take into account the possibility that IL-6 could be, as other interleukins (17), a bi-functional molecule having, beside a receptor-binding domain, a carbohydrate recognition domain (CRD). As demonstrated for interleukin 2 (IL-2; Ref.…”

“…Recent studies (17) demonstrated that IL-6 specifically binds to nervous tissue glycoproteins bearing the HNK-1 epitope (glucuronic acid 3-sulfate), the structure having been determined (23,24). The HNK-1 epitope is an onco-fetal antigen (25)(26)(27)(28)(29)(30), especially concentrated at early stages of development on glycoproteins considered as "cell-adhesion molecules": the N-CAM (31,32), the J1 glycoprotein (33), the myelin-associated glycoprotein (MAG; 4,34,35,36), the P0 myelin glycoprotein (6,37,38), the myelin-oligodendrocyte glycoprotein (MOG; Refs.…”

“…This epitope is also found on glycolipids (42)(43)(44), especially concentrated in human myelin. The binding of IL-6 to the myelin glycoproteins MAG and P0 (17) was reversed specifically using some oligosaccharide alditols having the HNK-1 epitope isolated from the mucins of the eggs of Rana temporaria (45). One of these compounds showed a very strong inhibitory property of the binding of IL-6 to the glycoprotein HNK-1 epitope, suggesting that it was a much higher affinity ligand than the glycoprotein HNK-1 epitope.…”