Porphyromonas gingivalis lipopolysaccharide promotes platelet spreading and thrombosis via Cdc42 activation
department or school: Dentistry, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Senini, Vincent
issued: 2019-08-31T00:00:00
issued: 2018
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Background: Chronic periodontitis confers an increased risk for cardiovascular diseases, including thrombosis. However, the molecular mechanisms that potentially link periodontitis with thrombosis are undefined. Here I tested the hypothesis that gram-negative periodontal infection promotes pathological platelet activation and shape change. I focused specifically on lipopolysaccharide (LPS) signaling through Cdc42. Methods: Platelets were isolated from blood samples and allowed to spread on coverslips in the presence or absence of LPS purified from the periodontal pathogen Porphyromonas gingivalis. Platelets were fixed and stained with Alexa- 488-phalloidin to label the actin cytoskeleton. The degree of platelet spreading and shape change were quantified by confocal microscopy. In a translational pilot study, blood samples were obtained from human subjects exhibiting generalized severe chronic periodontitis (SP) or healthy periodontium (HP). Rotational thromboelastometry (ROTEM) was used to quantify the rate of clot formation via the intrinsic coagulation pathway. Results: LPS-treated platelets exhibited significantly (p<0.05) greater spreading and higher numbers of actin-rich filopodia (cell extensions) than controls. I also found that LPS stimulation directly activated Cdc42, the small GTPase responsible for filopodial formation. Exposure of whole blood samples to LPS significantly (p<0.05) reduced clotting times. Blood from SP patients clotted significantly (p<0.05) more rapidly and exhibited reduced partial thromboplastin times (aPTT) relative to HP controls. Conclusion: This is the first study to suggest a mechanism by which P. gingivalis LPS drives Cdc42 activation and platelet spreading. These data are consistent with the notion that periodontitis promotes accelerated clot formation and an increased risk of thrombosis.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/66900
note: Porphyromonas gingivalis lipopolysaccharide promotes platelet spreading and thrombosis via Cdc42 activation by Vincent Senini B.Sc., The University of British Columbia, 2009 M.Sc., The University of British Columbia, 2011 D.D.S., University of Toronto, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Craniofacial Science) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2018 © Vincent Senini, 2018 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, a thesis/dissertation entitled: Porphyromonas gingivalis lipopolysaccharide promotes platelet spreading and thrombosis via Cdc42 activation submitted by Vincent Senini in partial fulfillment of the requirements for the degree of Master of Science in The Faculty of Graduate and Postdoctoral Studies Examining Committee: Hugh Kim Supervisor Edward Putnins Supervisory Committee Member Flavia Lakschevitz Supervisory Committee Member Babak Chehroudi External Examiner iii Abstract Background: Chronic periodontitis confers an increased risk for cardiovascular diseases, including thrombosis. However, the molecular mechanisms that potentially link periodontitis with thrombosis are undefined. Here I tested the hypothesis that gram-negative periodontal infection promotes pathological platelet activation and shape change. I focused specifically on lipopolysaccharide (LPS) signaling through Cdc42. Methods: Platelets were isolated from blood samples and allowed to spread on coverslips in the presence or absence of LPS purified from the periodontal pathogen Porphyromonas gingivalis. Platelets were fixed and stained with Alexa-488-phalloidin to label the actin cytoskeleton. The degree of platelet spreading and shape change were quantified by confocal microscopy. In a translational pilot study, blood samples were obtained from human subjects e…
has type: Thesis/Dissertation
date issued: 2018-09
is shown at: 10.14288/1.0371200
language: eng
degree discipline: Craniofacial Science
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/66900