Their role as receptors for Neisseria meningitidis[21], N. gonorrhoeae[22, 23], Mycobacterium tuberculosis[24], Enterococcus faecalis[25], Listeria monocytogenes[26], Streptococcus and Staphylococcus[27], Brucella[28], Escherichia coli[29] and even intracellular parasites such as Chlamidia pneumoniae[30] have been described. Besides this, it seems that binding of group A streptococci to GAGs leads to a cytoskeleton conformational change that allows pathogen penetration [31, 32]. The requirement of GAGs

for viral infection has been demonstrated, among others, for papilloma virus [33], herpes virus [34], and HIV [35]. Finally, it is known that GAGs act as receptors for Toxoplasma gondii[36], Leishmania[37] and Plasmodium[38]. However, the microbial ligands involved in most of these processes have not yet been identified. This role of PGs as the eukaryotic learn more receptors for many pathogens is the basis of our initial hypothesis which suggests the same function of these molecules when interacting with autochthonous no pathogenic microorganisms such as lactobacilli.

In this report we provide data on the involvement of GAGs in attachment of Lactobacillus salivarius Lv72, isolated from a human vaginal exudate, to cultures of HeLa cells. Based on these data, a bacterial adhesin was identified which, once purified, significantly interfered with attachment of the lactobacilli to HeLa cell cultures. GSK-3 activity Results Interference of GAGs on HeLa cell-Lactobacillus salivarius Lv72 adhesion To study the role of GAGs on Lv72 adhesion to HeLa cells, addition of commercial preparations of HS, heparin, CS A or CS C to HeLa to cell monolayers was performed

immediately before until the addition of exponentially growing L. salivarius Lv72 cells. The results showed a decrease in the adherence between them (Figure 1). This depletion, although being dose dependent, does not follow a linear correlation. The estimated dissociation constants (KD) were of 2.5 nM for HS, 6.8 nM for CS A, 39.9 nM for CS C and 280.9 nM for heparin, which indicates that the affinity of the bacteria for the different receptors varied markedly, up to two orders of magnitude between HS and heparin. However, care must be taken with this interpretation, as the KDs are approximate values. Surprisingly, CS B did not produce any inhibitory effect, and even promoted a slight increase in the adhesion (Figure 1). Remarkably, the combined use of these GAGs dramatically increased the inhibition, reaching values up to 85% and 90% at total concentrations of 10 and 100 μg/ml respectively, although this effect was not strictly additive (Figure 1A). Figure 1 Inhibition of Lactobacillus attachment to HeLa cells by the presence of different GAGs.