Mediation of adherence of streptococci to human endothelial cells by complement S protein (vitronectin).
The role of S protein in the adherence of group A and G streptococci to human umbilical vein endothelial cells cultivated in 96-well microdilution plates was studied by utilizing fluorescein-labeled streptococci. The assay proved suitable for quantitative determination of bacterial adherence to cultured endothelial cells for all tested strains of streptococci. Only bacterial strains with significant S protein binding but weak fibronectin binding were included in these studies. Fibronectin-mediated adherence to endothelial cells of these streptococci was less than 25% of total and could be blocked by antifibronectin immunoglobulin G. Further treatment of endothelial cell monolayers with anti-S protein immunoglobulin G at concentrations up to 1 mg per well led to an almost complete inhibition of adherence for all tested streptococcal cultures, indicating significant contribution of S protein in the streptococcus-endothelial cell interaction. Blocking of S-protein-binding sites on streptococci by preincubation with exogeneous S protein at a concentration of 10 micrograms per 4 x 10(7) streptococci led to about 75% reduction of S-protein-mediated adherence to endothelial cells. Trypsin pretreatment of group G streptococci and pronase pretreatment of group A and G streptococci, modifications known to destroy the bacterial binding sites of S protein, also inhibited the capacity of the streptococci for S-protein-mediated adherence to endothelial cells by 75 to 80%. These results indicate that S protein plays a mediatory role in adherence of streptococci to endothelial cells and that S-protein-specific binding sites on streptococci are involved in this interaction.
Valentin-Weigand
P
P
Institute for Bacteriology and Immunology, Max-Planck-Gesellschaft, Justus-Liebig-Universität, Giessen, Federal Republic of Germany.
Grulich-Henn
J
J
Chhatwal
G S
GS
Müller-Berghaus
G
G
Blobel
H
H
Preissner
K T
KT
D001422:Bacterial Adhesion; D001665:Binding Sites; D004730:Endothelium, Vascular / Q000382:microbiology*; D005353:Fibronectins / Q000502:physiology; D006023:Glycoproteins / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D010447:Peptide Hydrolases / Q000494:pharmacology; D011485:Protein Binding; D013291:Streptococcus / Q000502:physiology*; D019096:Vitronectin
D005353:Fibronectins; D006023:Glycoproteins; D019096:Vitronectin; D010447:Peptide Hydrolases