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Effects of treponema denticola on an oral epithelial cell model Leung, Wai Keung
Abstract
Periodontal diseases are destructive inflammatory conditions of the tissues supporting the tooth. The inflammatory responses are induced by mixed bacterial infection leading to eventual destruction of the periodontal tissue. Oral spirochetes of the genus Treponema are one of the bacterial groups that are closely related to these diseases. This study investigated the interaction of a periodontal pathogen, T. denticola, its whole cells and outer membrane (OM) proteins with cultured eukaryotic cells. Cultured porcine periodontal ligament epithelial cells (PLE, a junctional epithelium model), and various cell lines were challenged with T. denticola ATCC 35405 whole cells or with the major OM protein (Msp) complex, gel purified Msp, and chymotrypsin-like proteinase (CTLP). Msp complex was isolated from whole T. denticola by detergent extraction, autoproteolysis, ultrafiltration and detergent removal. The location of the Msp and CTLP on T. denticola OM was studied. Hexagonal array was observable on negative-stained T. denticola OM under electron microscope where Msp probably constituted the main building block of the regular pattern together with the previously reported OM located CTLP. Native T. denticola Msp is an oligomer containing 53 kDa protein subunits which had porin activity in an artificial lipid bilayer. CTLP was previously characterized. Microscopic and modified ELISA assays showed that spirochetes adhered to PLE cells whether prefixed with glutaraldhyde (fixed PLE-FPLE) or not. Pre-treatment of T. denticola with the protease inhibitor TV-tosyl-L-phenylalanine chloromethyl ketone or phenylmethanesulfonyl fluoride blocked this binding and chymotrypsin-like activity. T. denticola intact or sonicated whole cells were cytotoxic to PLE cells and to several cell lines. T. denticola cytotoxicity was measured by microculture tetrazolium assay or by quantifying lactate dehydrogenase release upon cell lysis (LDH assay). T. denticola induced PLE cellular changes were observed by light microscopy, image analysis and electron microscopy. These included: transient cell size increase of non-detached PLE cells leading to confluency maintenance, membrane disruption, vacuolation, loss of cell contacts, loss of cell size control, cytoskeletal rearrangement, and apoptosis of PLE cells. Msp complex, Msp and CTLP could attach to PLE/FPLE and were found to be cytotoxic to PLE cells. Adherence of Msp was partially blocked by specific antibodies. Adherence of CTLP was partially blocked by serine protease inhibitors and was further inhibited by specific antibodies. Cytotoxicity of Msp and CTLP was inhibited by the same treatments that inhibited adherence. Standard patch clamp recording methods were used to study the effects of Msp complex on HeLa cells. Msp bound to several HeLa cell proteins, including a 65 kDa surface protein and a 96 kDa cytoplasmic protein. The Msp complex depolarized and increased the conductance of the HeLa cell membrane in a manner that was not strongly selective for Na+, K+ , Ca2+, and CI" ions. Cell-attached patches of HeLa cell membrane exposed to Msp complex exhibited short-lived channels with a slope conductance of 0.4 nS in physiologically normal saline. These studies show that T. denticola ATCC 35405 and its major OM protein elements, namely Msp and CTLP, could attach to a cell model that resembles junctional epithelium and could produce cytopathic and cytotoxic effects. It was hypothesized that the strong proteolytic activities of CTLP and pore-forming activity of the Msp complex were responsible for the cytopathic and cytotoxic effects of the putative periodontopathogen T. denticola on PLE cells.
Item Metadata
Title |
Effects of treponema denticola on an oral epithelial cell model
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1998
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Description |
Periodontal diseases are destructive inflammatory conditions of the tissues supporting the tooth.
The inflammatory responses are induced by mixed bacterial infection leading to eventual
destruction of the periodontal tissue. Oral spirochetes of the genus Treponema are one of the
bacterial groups that are closely related to these diseases. This study investigated the interaction
of a periodontal pathogen, T. denticola, its whole cells and outer membrane (OM) proteins with
cultured eukaryotic cells. Cultured porcine periodontal ligament epithelial cells (PLE, a
junctional epithelium model), and various cell lines were challenged with T. denticola ATCC
35405 whole cells or with the major OM protein (Msp) complex, gel purified Msp, and
chymotrypsin-like proteinase (CTLP). Msp complex was isolated from whole T. denticola by
detergent extraction, autoproteolysis, ultrafiltration and detergent removal. The location of the
Msp and CTLP on T. denticola OM was studied. Hexagonal array was observable on negative-stained
T. denticola OM under electron microscope where Msp probably constituted the main
building block of the regular pattern together with the previously reported OM located CTLP.
Native T. denticola Msp is an oligomer containing 53 kDa protein subunits which had porin
activity in an artificial lipid bilayer. CTLP was previously characterized. Microscopic and
modified ELISA assays showed that spirochetes adhered to PLE cells whether prefixed with
glutaraldhyde (fixed PLE-FPLE) or not. Pre-treatment of T. denticola with the protease inhibitor
TV-tosyl-L-phenylalanine chloromethyl ketone or phenylmethanesulfonyl fluoride blocked this
binding and chymotrypsin-like activity. T. denticola intact or sonicated whole cells were
cytotoxic to PLE cells and to several cell lines. T. denticola cytotoxicity was measured by
microculture tetrazolium assay or by quantifying lactate dehydrogenase release upon cell lysis
(LDH assay). T. denticola induced PLE cellular changes were observed by light microscopy, image analysis and electron microscopy. These included: transient cell size increase of non-detached
PLE cells leading to confluency maintenance, membrane disruption, vacuolation, loss
of cell contacts, loss of cell size control, cytoskeletal rearrangement, and apoptosis of PLE cells.
Msp complex, Msp and CTLP could attach to PLE/FPLE and were found to be cytotoxic to PLE
cells. Adherence of Msp was partially blocked by specific antibodies. Adherence of CTLP was
partially blocked by serine protease inhibitors and was further inhibited by specific antibodies.
Cytotoxicity of Msp and CTLP was inhibited by the same treatments that inhibited adherence.
Standard patch clamp recording methods were used to study the effects of Msp complex on HeLa
cells. Msp bound to several HeLa cell proteins, including a 65 kDa surface protein and a 96 kDa
cytoplasmic protein. The Msp complex depolarized and increased the conductance of the HeLa
cell membrane in a manner that was not strongly selective for Na+, K+ , Ca2+, and CI" ions. Cell-attached
patches of HeLa cell membrane exposed to Msp complex exhibited short-lived
channels with a slope conductance of 0.4 nS in physiologically normal saline. These studies
show that T. denticola ATCC 35405 and its major OM protein elements, namely Msp and CTLP,
could attach to a cell model that resembles junctional epithelium and could produce cytopathic
and cytotoxic effects. It was hypothesized that the strong proteolytic activities of CTLP and pore-forming
activity of the Msp complex were responsible for the cytopathic and cytotoxic effects of
the putative periodontopathogen T. denticola on PLE cells.
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Extent |
18672431 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-22
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0103814
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1998-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.