Effects of dipeptide bestatin on Porphyromonas gingivalis and epithelial cells.
BACKGROUND
Dipeptide bestatin has been previously reported to selectively inhibit the growth of Porphyromonas gingivalis. The aims of this study were to investigate the mechanism of action of bestatin and to evaluate its effect on epithelial cells.


METHODS
The inhibitory effect of bestatin on P. gingivalis was tested in vitro (culture medium) and in vivo (guinea pig model). Radiolabeled compounds were used to investigate the effect of bestatin on the uptake of amino acids and peptides. The cytotoxic effect of bestatin was evaluated using a keratinocyte cell line.


RESULTS
The growth inhibition of P. gingivalis by bestatin was concentration-dependent. Even at high concentrations, compounds possessing a chemical structure or an aminopeptidase inhibitor activity related to bestatin had no effect on growth of P. gingivalis. When injected in the presence of P. gingivalis, bestatin was able to prevent the development of a necrotic abscess in a guinea pig model. Data were obtained suggesting that bestatin does not act on proteinases of P. gingivalis. Rather, bestatin was found to inhibit the intracellular uptake of radioactivity from 14C-labeled amino acids or heat-denatured type I collagen. This was not observed with a spontaneous mutant of P. gingivalis, whose growth was not affected by bestatin. In the second part of the study, bestatin was found to have no effect on epithelial cell viability in culture at concentrations effective on P. gingivalis. In addition, bestatin did not show effects on epithelial cell migration or production of gelatinases.


CONCLUSIONS
This study suggests that bestatin selectively inhibits growth of P. gingivalis by affecting the intracellular uptake of amino acids and peptides, which serve as energy and nitrogen sources for this bacterial species. Bestatin has no cytotoxicity and may represent a therapeutic molecule for local treatment of P. gingivalis-associated periodontitis.
Labbé
S
S
Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Quebec City, PQ.
Grenier
D
D
Plamondon
P
P
Uitto
V J
VJ
Mayrand
D
D
D000038:Abscess / Q000382:microbiology / Q000517:prevention & control; D000596:Amino Acids / Q000037:antagonists & inhibitors; D000626:Aminopeptidases / Q000037:antagonists & inhibitors*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D016866:Bacteroidaceae Infections / Q000517:prevention & control; D002250:Carbon Radioisotopes; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003094:Collagen / Q000037:antagonists & inhibitors; D015169:Colony Count, Microbial; D003470:Culture Media; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects; D018093:Gelatinases / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects; D007930:Leucine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000633:toxicity; D010455:Peptides / Q000037:antagonists & inhibitors; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000254:growth & development; D011480:Protease Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D019275:Radiopharmaceuticals
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D002250:Carbon Radioisotopes; D003470:Culture Media; D010455:Peptides; D011480:Protease Inhibitors; D019275:Radiopharmaceuticals; D003094:Collagen; D000626:Aminopeptidases; D018093:Gelatinases; D007930:Leucine; C012211:ubenimex