Binding of Streptococcus mutans SR protein to human monocytes: production of tumor necrosis factor, interleukin 1, and interleukin 6

Abstract

To examine the possible implication of protein SR, an VII-related antigen from Streptococcus mutans OMZ 175 (serotype f), in inflammatory reactions, we tested the immunomodulatory effects of protein SR on human monocytes. Using biotinylated protein, we provide evidence that protein SR binds to human monocytes in dose-, time-, and calcium-dependent manners through specific interactions. These results were confirmed by competition experiments using either soluble human monocyte extract or anti-SR immunoglobulin G. Binding occurred through lectin-like interactions between SR and carbohydrate portions of monocyte membrane glycoproteins, since binding could be inhibited by several sugars, especially fucose and N-acetylneuraminic acid (NANA), which were confirmed by ligand blotting to be the primer ligands recognized by SR on human monocyte extracts. The ability of protein SR to stimulate the production of cytokines by human circulating monocytes was then examined. The release of tumor necrosis factor alpha (TNF-a), interleukin 1p, and interleukin 6 is time and dose dependent and not affected by the addition of polymyxin B. Activation of monocytes resulted from specific binding of SR to NANA and fucose present on cell surface glycoproteins since TNF-a release could be inhibited by sialidase and pronase treatment of monocytes and by NANA and fucose. These results confirm that sialic acid and fucose present on cell surface macromolecules and especially glycoproteins are needed for the binding of SR to monocytes and for the release of TNF-a.

Tumor necrosis factor‐α and interleukin‐1β expression pathway induced by Streptococcus mutans in macrophage cell line RAW 264.7

“…2). These results are similar to other reports showing that S. mutans stimulates the production of TNF-a and IL-1b in human peripheral blood mononuclear cells or human monocytes, or the S. mutans OMZ175 protein I/II induces the production of TNF-a and IL-1b in human synoviocytes (Benabdelmoumene et al, 1991;Soell et al, 1994;Jiang et al, 1999;Gourieux et al, 2001). Nuclear factor-jB is a multiunit transcription factor that plays a key role in the induction of genes for proinflammatory cytokines (Collart et al, 1990;Ziegler-Heitbrock et al, 1993;Neff et al, 2001) as well as many other immunoregulatory genes (Baeuerle, 1991).…”

NF-kappaB and the MAP kinases/AP-1 pathways are both involved in interleukin-6 and interleukin-8 expression in fibroblast-like synoviocytes stimulated by protein I/II, a modulin from oral streptococci

“…Most species of oral streptococci express on their cell surface a high-molecular-mass polypeptide of the I/II family, which is a multifunctional adhesin with multiple ligand binding sites. This protein binds chiefly to salivary constituents such as salivary glycoproteins (Crowley et al, 1993) either in the fluid phase or adsorbed to hydroxyapatite, to human epithelial, endothelial and monocytic cells, and binding to cells occurs via lectin interactions specific for N-acetyl neuraminic acid and fucose (Soell et al, 1994;Vernier et al, 1996). Moreover, we and others (Love et al, 1997;Sciotti et al, 1997) have demonstrated the capacity of protein I/II to bind to extracellular and matrix proteins such as collagen I, laminin and fibronectin, which suggests the propensity of the bacteria or bacterial components to disseminate and persist in tissues.…”

Involvement of alpha5beta1 integrins in interleukin 8 production induced by oral viridans streptococcal protein I/IIf in cultured endothelial cells

“…There is now evidence that protein I/IIf is involved in the adhesion of oral viridans streptococci to salivary glycoproteins, either in the¯uid phase or adsorbed to hydroxyapatite (Demuth et al, 1989;Lee et al, 1989;Brady et al, 1992;Munro et al, 1993;Moisset et al, 1994), and that protein I/IIf plays a role in virulence by interacting speci®cally with¯uid phase salivary agglutinins to mediate bacterial aggregation (Demuth et al, 1996;Kuykindoll and Holt, 1996;Crowley et al, 1999). Moreover, we and others have demonstrated the capacity of protein I/IIf to bind to extracellular matrix proteins, such as ®bronectin, collagen I and laminin (Love et al, 1997;Sciotti et al, 1997), and to epithelial, endothelial and monocytic cells (Soell et al, 1994;Vernier et al, 1996). We demonstrated recently that the speci®c binding of protein I/IIf from Streptococcus mutans serotype f to monocytic THP-1 cells occurs via lectin interactions spec-i®c for N-acetyl neuraminic acid (NANA) and fucose and is controlled by the extended V-region (Chatenay-Rivauday et al, 1998).…”

“…We demonstrated recently that the speci®c binding of protein I/IIf from Streptococcus mutans serotype f to monocytic THP-1 cells occurs via lectin interactions spec-i®c for N-acetyl neuraminic acid (NANA) and fucose and is controlled by the extended V-region (Chatenay-Rivauday et al, 1998). We also showed that (i) the binding of members of the oral viridans streptococci to cells induces the release of pro-in¯ammatory cytokines by epithelial and endothelial cells (Vernier et al, 1996); (ii) protein I/IIf belongs to the recently de®ned class of modulins and exerts immunomodulatory effects on human cells (Soell et al, 1994;Vernier et al, 1996). After binding to its cognate receptor, protein I/IIf promotes the induction of IL-8 from epithelial cells, IL-8 and IL-6 from endothelial cells, IL-1b, tumour necrosis factor alpha (TNF-a) and IL-6 from monocytes and the upregulation of E-selectin, ICAM-1 and VCAM-1 expression on endothelial cells (Vernier-Georgenthum et al, 1998).…”

“…In inhibition experiments, protein I/IIf (50 mg ml À1 ) was either preincubated with increasing amounts of a5b1 integrins for 2 h at 48C before incubation in microtitre plates coated with HSVEC-solubilized NP-40 proteins, or incubated simultaneously in plates coated with HSVEC-solubilizing NP-40 proteins with increasing amounts of anti-integrin b1 chain mAbs. In some experiments, HSVECs were biotinylated according to the method described by Weersink et al (1993), and NP-40 extracts were obtained as described above (Soell et al, 1994). Direct binding of increasing amounts of biotinylated NP-40 proteins to microtitre plates coated with puri®ed protein I/II (1 mg ml À1 ) in 0.1 M carbonate buffer was performed as described above.…”