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Bacteria degrade the specialized basal lamina attaches the gingiva to teeth
Author(s) -
Fouillen Aurélien,
Grenier Daniel,
Barbeau Jean,
Baron Christian,
Moffatt Pierre,
Nanci Antonio
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.38.7
Subject(s) - basal lamina , chemistry , bacteria , western blot , biophysics , laminin , microbiology and biotechnology , extracellular matrix , biochemistry , biology , anatomy , ultrastructure , genetics , gene
The junctional epithelium is a specialized portion of the gingiva that seals off the tooth supporting tissues from the oral environment. This relationship is achieved via a specialized basal lamina (sBL). Three unique proteins ‐AMTN, ODAM and SCPPPQ1‐ together with Laminin‐332 structure the supramolecular organization of this sBL and determine its adhesive capacity. Despite its critical and strategic importance and continued exposure to bacteria, little is known on the susceptibility of the sBL to bacterial activity. Methods The objective of this study was to evaluate the impact of various oral bacteria on the sBL using molecular biology and complementary imaging approaches. Results SDS‐PAGE and western blot analysis of degradation assays with trypsin like proteases as well as incubation with Porphyromonas gingivalis ( P. gingivalis ) revealed that all sBL constituents, except SCPPPQ1, were rapidly degraded. Mass spectrometry also confirmed that SCPPPQ1 was not degraded. We have previously shown that mixing the recombinant sBL proteins results in the formation a supramolecular network that mimicked the sBL. To observe the impact of oral bacteria on this ‘reconstituted’ sBL network, we exposed it to P. gingivalis and observed the results by atomic force microscopy and scanning electron microscopy (SEM). The bacteria destroyed the supramolecular network in their vicinity creating a peripheral space around them. SEM imaging further showed the presence of fine filamentous residual matrix on the exposed HOPG surface, suggesting the incomplete degradation of some component and a layered destruction of the network. Finally, to determine the effect of P. gingivalis on the native sBL itself, we exposed it ex‐vivo to bacteria. After two hours of exposure, SEM analysis revealed the presence of a shallow depression around the bacteria and after 6 h, the affected peri‐bacterial area became deeper and cavitated , suggesting active degradation of the native sBL as well. Conclusion We show here for the first time that enzymes and P. gingivalis , one of the major bacteria implicated in chronic periodontitis, can attack the individual components of the sBL as well as alter the supramolecular organization of this critical adhesive extracellular matrix. Because destruction of the sBL would open the door to bacterial infiltration around teeth. These results highlight the importance of the sBL in PD and open the door for new treatment paradigms. Support or Funding Information This work was supported by CIHR, Canada Research Chair, RSBO, and Shriners Hospital. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .