TNF-α release by monocytic THP-1 cells through cross-linking of the extended V-region of the oral streptococcal protein I/II

Histone-like DNA binding protein of Streptococcus intermedius induces the expression of pro-inflammatory cytokines in human monocytes via activation of ERK1/2 and JNK pathways

“…Recognition of PAMP by the involved host cells, primarily neutrophils, monocytes and dendritic cells, leads to pro-inflammatory responses, including the release of cytokines, chemokines and other mediators, which are required for an effective host response (Medzhitov and Janeway, 1997); however, a range of other molecules from bacteria also has the capacity to induce cytokine production (Henderson et al, 1996). Streptococci have several functional proteins which are involved in the host proinflammatory response, such as pneumolysin of S. pneumoniae (Houldsworth et al, 1994;Rogers et al, 2003;Thornton and McDaniel, 2005), mitogenic exotoxin Z, pyrogenic exotoxin A and M protein of S. pyogenes (Muller-Alouf et al 2001;Pahlman et al, 2006), and antigen I/II of S. mutans (Soell et al, 1994) and other streptococci (Chatenay-Rivauday et al, 2000). This study is the first report showing that the histone-like DNA binding protein of S. intermedius (Si-HLP), a highly conserved structural protein within streptococci, is a potent activator upregulating pro-inflammatory cytokines in human monocytes.…”

Expression and Functional Properties of the Streptococcus intermedius Surface Protein Antigen I/II

“…These proteins have received a variety of names according to the strains or species in which they were identified, such as antigen B (40), Sr (35), I/II (20), and PAc (37) from Streptococcus mutans; SpaA from Streptococcus sobrinus (25,45); and SspA and SspB from two tandemly arranged genes in Streptococcus gordonii (7). Multifunctional activities are attributed to the antigen I/II family, i.e., binding to soluble extracellular matrix glycoproteins (41) and to host cell receptors (42,47), coaggregation with other microorganisms (4,15,24), interactions with salivary glycoproteins (3,9,12,19,21,27,36), and activation of monocytic cells (1,5,6). Members of the antigen I/II family may, however, exhibit functional species specificity.…”

“…Differences in antigen I/II binding properties, mechanisms, and affinities have, for instance, been described for S. gordonii and S. mutans (18). Enzyme-linked immunosorbent assays (32), DNA hybridization studies (30), and homologous PCR-amplified sequences (6,30) indicate that the anginosus group of streptococci also expresses an antigen I/II-like protein. In S. intermedius, limited information is available on the structure, expression and function of this protein.…”

Cloning and DNA sequencing of the surface protein antigen I/II (PAa) of Streptococcus cricetus

“…Complete DNA sequence information about pac homologs have been obtained from Streptococcus sobrinus (SpaA [7] or PAg [8]) and Streptococcus gordonii (SspA and SspB [9]). In addition, pac homologs are partially sequenced from Streptococcus oralis, Streptococcus intermedius and Streptococcus constellatus [6,10]. Although members of the PAc family closely resemble one another in their primary sequences, they di¡er in binding a¤nities with human cells, salivary agglutinin glycoprotein and microbial cells [11].…”