Teichoic acids of Streptococcus agalactiae: chemistry, cytotoxicity, and effect on bacterial adherence to human cells in tissue culture

Abstract

The ratio of teichoic acid to lipoteichoic acid (LTA) in a strain of Streptococcus agalactiae type III was found to be 8:1, with the total amount of LTA being 0.1% of the dry weight of the organism. Purified teichoic acid contained D-alanine and possibly a small amount of D-glucose and was approximately 22 glycerol phosphate units in length. The linkage between each of these units was 1-3. In addition, LTA contained a complex lipid, more glucose, and an unusually high content of a short-chain fatty acid, tridecanoic acid. This LTA was cytotoxic for a variety of human cell monolayers in tissue culture, including one derived from the human central nervous system. Established human cells were more sensitive than primary cell monolayers to this LTA, with as little as 12.5 ,ug of LTA per ml being cytotoxic for HeLa cells. Teichoic acid (250 Fig/ml) was nontoxic under identical conditions. These cytotoxicity results suggest an LTA involvement in group B streptococcal pathogenesis. Also, the first model system for the study of group B streptococcal adherence to primary human embryonic amnion cells in tissue culture is detailed. This system was used to quantitate pronounced differences in tissue tropism between S. agalactiae and Streptococcus pyogenes and showed enhanced binding by this group A coccus over that of S. agalactiae for amnion cell monolayers. The adherence of both streptococcal species to only a portion (40%) of these amnion cells suggested that host cell receptor expression may vary for primary cells in vitro. Finally, this strain of S. agalactiae was shown to adhere to amnion cells by a non-LTA-mediated mechanism. The possibility of an LTA-mediated versus a protein-mediated adherence mechanism for host cells that is related to the virulence of S. agalactiae is discussed. Group B streptococci are important pathogens of infants during the neonatal period. These organisms also produce disease in adults (37). Of all the serotypes known, type III strains account for the largest proportion of infections in humans (16). Studies of the physiology of this pathogen have dealt with cell wall composition (9), extracellular enzymes (31), and the release of soluble antigens (11). However, except for an earlier study by McCarty (22) which established the presence of a glycerol-type teichoic acid (TA) in a group B streptococcus, serotype unknown, the TA of these cocci has not been detailed. The important role of lipoteichoic acid (LTA) in bacterial adherence to host cells (3, 4) and its putative role in immunological and immunopathological (35) maladies is now well established. More recently, the ability of LTA from a group A streptococcus to destroy * Corresponding author. MATERIALS AND METHODS Bacteria. S. agalactiae type III, a human isolate designated DS2242-77, was obtained from Richard R. Facklam, Centers for Disease Control, Atlanta, Ga. The Streptococcus pyogenes type 12 used as a control has been described

Characterization of Group B Streptococcal Invasion of Human Chorion and Amnion Epithelial Cells In Vitro

“…We found that GBS adhered to the chorion cell surface, invaded, and survived within these cells long enough to transcytose through intact chorion cell monolayers. GBS adhered to primary amnion cells, consistent with previous reports (15), but failed to invade, suggesting that these cells may provide a barrier to penetration of the amniotic membrane.…”

Adherence of group B streptococci to human endothelial cells in vitro

“…Moreover, there was a correlation between binding to HUVEC with that to the plastic surface, such that strains with high affinity for HUVEC also bound significantly to plastic. This finding suggests that nonspecific forces together with specific binding mechanisms such as lipoteichoic acid-binding and lectin-like interactions participate in binding of GBS to endothelial cells (1,9,17). In other systems charge and hydrophobicity have been shown to significantly affect bacterial binding (15).…”

Factors Influencing Adherence of Streptococcus dysgalactiae to Bovine Mammary Epithelial Cell Monolayers

“…This fragment is unique for the bovine species, corresponds to DNA between nucleotides 10 592 and 11 466 of the bovine Kcasein gene (ALEXANDER et al, 1988), and has been used through restriction length polymorphism analysis to ascertain the genotype of cattle at the rc-casein locus (PINDER et al, 1991). Primary cultures of bovine mammary epithelial cells and a transformed bovine mammary epithelial cell line have been used as an in v h model to study cytotoxicity as well as adherence of bacterial pathogens to epithelial cells, Primary cultures of mammary epithelial cells, although placed in an unnatural environment, are considered to resemble more closely actual cells in viva (OLMSTED and NORCROSS, 1992;CIFRIAN et d., 1995); while transformed mammary epithelial cells offer the advantage of homogeneity of target cells used in each experiment, although the process of transformation might affect the expression of surface receptors (GOLDSCHMIDT and PANOS, 1984;OLMSTED and NORCROSS, 1992).…”

“…This cannot be attributed to the higher number of cells per well in MAC-T monolayers since similar bacterial:epithelial cell ratios were taken into consideration for comparisons. Differences in bin-affinity of groups A and B streptococci between freshly obtained and transformed cell lines have been observed and have been considered to reflect a distinct availability of receptors in either cell type (GOLDSCHMIDT and PANOS, 1984;COURTNEY et al, 1992).…”