Biologically active substances produced by Bacteroides gingivalis and their periodontopathogenicity

点击翻译按钮获取中文摘要

Bacteroides gingivalis produces several types of biologically active substances. The purpose of this investigation is to determine the properties of these substances such as proteases, hemagglutinin and tissue-cell agglutinating factor etc. in association with periodontopathogenicity and cytotoxicity.Hemagglutinin (HA), which is considered to participate in the bacterial adherence to host tissues, was isolated and purified from the culture supernatant. The receptor protein of the erythrocyte for this HA was clarified to be band 3 protein and the arginine residue of the peptide was concerned in the binding. This HA possessed both the trypsin-like and the tissue-cell aggregating activities, suggesting that hemagglutination may occur as a result of enzyme-substrate reaction between the trypsin-like enzyme and the band 3 protein.The trypsin-like enzyme produced by B.gingivalis showed the ability of hydrolyzing type I collagen, IgG, IgA and some other naturally occurring proteins. This enzyme also had strong cytotoxicity on human gingival fibroblasts. These facts indicate that the enzyme exhibits pathogenicity not only by destroying periodontal tissue directly but also by decreasing host immune defense ability.All these biologically active substances are concentrated in the secreted outer membrane vesicles of B.gingivalis and all of them behaved in the same way on several protease inhibitors. These results suggest that the true feature of the pathogenic factor of B.gingivalis could be the trypsin-like protease which associates with the outer membrane vesicles.