Fimbriae and the hemagglutinating adhesin HA-Ag2 mediate adhesion of Porphyromonas gingivalis to epithelial cells

Abstract

The mechanisms by which Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is pathogenic for the periodontium remain largely hypothetical. Invasion of host tissues by P. gingivalis is believed to require adhesion of the bacterium to host cells. The aim of this study was to use monoclonal antibodies (MAbs) to characterize the bacterial cell surface component(s) acting as a ligand binding to a receptor on epithelial cells. Surface antigens of P. gingivalis ATCC 33277 were obtained as a glass bead-EDTA extract (GBE), and antiserum against the GBE was produced in rabbits. Epithelial cell membrane proteins (ECMP) were prepared from a homogenate of the SK-MES-1 cell line with Triton X-100. The antigen/ligand profile of GBE was resolved by crossed immunoaffinity electrophoresis by using ECMP in the first-dimension gel. The migration of one immunoprecipitate (IP) was retarded, indicating a ligand-receptor interaction between a surface antigen of P. gingivalis and a complementary binding site on the epithelial cell membrane. The corresponding IP in the GBE/anti-GBE immunoelectrophoresis profile was excised from replicate gels to immunize mice for production of MAbs specific for the bacterial ligand. Five MAbs were obtained and tested for reactivity with GBE in immunoblots and for inhibition of the interaction between GBE and ECMP. Immunoblots revealed polypeptides at 28, 42, 43, and 49 kDa. Inhibition tests were positive for all five MAbs. These results are conclusive evidence that the MAbs recognize functional epitopes involved in the adherence of P. gingivalis to epithelial cells and that the adhesins are likely associated with fimbriae and the hemagglutinating adhesin HA-Ag2.

Antigens of bacteria associated with periodontitis

“…The 33 and 38 kDa HA-Ag2 proteins were extracted using an EDTA containing buffer whereas the 43 and 49 kDa forms were isolated from extracellular vesicles. Spe-ci®c antibodies to HA-Ag2 have been shown to inhibit haemagglutination and binding of P. gingivalis to epithelial cells (28,49,315). A number of studies have identi®ed four P. gingivalis genes that encode haemagglutinin proteins HagA, B, C, and D (191,192,278,279).…”

Adhesion of Porphyromonas gingivalis. Serotypes to Pocket Epithelium

“…2,3,5 This has been attributed to differences between their surface characteristics. 2,7,8 The presence of fimbriae seems important, as decreased adhesion capacity is seen for fimbriae-deficient mutants of P. gingivalis 9 and when specific antibodies against fimbriae are applied prior to adhesion assays. 7 Different capsular serotypes are known for P. gingivalis.…”

“…2,7,8 The presence of fimbriae seems important, as decreased adhesion capacity is seen for fimbriae-deficient mutants of P. gingivalis 9 and when specific antibodies against fimbriae are applied prior to adhesion assays. 7 Different capsular serotypes are known for P. gingivalis. 10 In addition to a non-encapsulated type, 6 different capsular (K) serotypes have been described for P. gingivalis.…”

Porphyromonas gingivalis Fimbriae Induce Adhesion of Monocytic Cell Line U937 to Endothelial Cells

“…Porphyromonas gingivalis fimbriae are important cell structures involved in adherence of the bacterium to periodontal tissues and may also be important in other virulence properties of this organism (6,9,14). Many investigators have demonstrated the infiltration of monocytes/macrophages into periodontal tissues of individuals with adult periodontal disease, a chronic inflammatory disease (8,19,22).…”