Enterococcus Faecalis has Collagenolytic Activity that Degrades Human Dentin Collagen Matrix

Marashdeh, Muna 1, 2 ;  Gitalis, Russel 1, 2 ;  Celine, Levesque 1 ;  Friedman, Shimon 1 ;  Finer, Yoav 1, 2

1. Faculty of Dentistry, University of Toronto; 2. Institute of Biomaterials and Biomedical Engineering, University of Toronto

Background: Collagen is the major component in dentin organic matrix; it preserves the structural integrity of dentin. Bacterial infections caused by coronal leakage is an important cause of endodontic failure. Bacterial enzymes may contribute to the degradation of collagen fibrils, undermining the sealer-dentin interface integrity. Enterococcus faecalis is a bacterial species commonly detected in persistent periapical infections. The ability of E. faecalis to cause infections has been linked to several virulence factors.

Hypothesis: E. faecalis possesses a collagenolytic activity that enables the bacteria to degrade the dentinal collagen matrix.

Methodology: Proteases activity in E. faecalis toward generic and specific human matrix metalloproteinases (MMPs) was measured using the SensoLyte MMP Assay Kit (AnaSpec). The ability of E. faecalis to degrade the dentinal collagen in the demineralized dentin was tested by quantifying the amount of hydroxproline released in the supernatant and by observing the tissues under scanning electron microscopy (SEM).

Results: E. faecalis showed generic and specific MMP-like activities with mean ± SD of 5.17 ± 0.47, 4.07 ± 0.14, 1.32 ± 0.24, 7.75 ± 0.88, and 5.98 ± 0.61 µM for MMP-1, -2, -8, and -9, respectively. The amount of hydroxyproline (µg) released by E. faecalis (1.8±0.17) was significantly higher (p<0.05) compared to heat-inactivated bacteria (0.61±0.22) after 24 h of incubation. SEM showed evidence of collagen network degradation after incubation with E. faecalis vs. no cell control.

Conclusions: E. faecalis possesses a collagenolytic activity that enables the bacteria to degrade dentinal collagen, potentially compromising the interface and tooth structure.

Significance: The presence of collagenolytic activity may facilitate the migration of E. faecalis from the root canal into the periapical lesion and may explain the role of Enterococci in apical periodontitis. Anti-collagenolytic sealers and/or treatment could be used to mitigate the effect of the bacteria.