Periodontal diseases are one of the most common bacterial infections of humans and impose a significant burden on the health care system. One of the predominant pathogens in periodontal disease is the gram- negative anaerobe P. gingivalis. However, P. gingivalis can also inhabit the oral cavity in the absence of overt disease and can participate in a balanced interaction with host cells. Epithelial cells that line the gingival crevice function both as a physical barrier and as sensors of microbial colonization. The outcome of the interaction between P. gingivalis and gingival epithelial cells, therefore, makes a significant contribution to the degree of equilibrium between host and microbe, and to overall gingival health status. P. gingivalis can manipulate epithelial cell signal transduction pathways in order to direct entry into the host cell and to reprogram host innate immunity. One of the effector molecules of P. gingivalis is the HAD family serine phosphatase, SerB. The goal of this proposal is to define the mechanism of action of SerB as it relates to uptake of the organism by gingival epithelial cells and modulation of innate immunity. Firstly, the ability of SerB to dephosphorylate and activate cofilin will be examined. Cofilin regulates actin dynamics through mediating the disassembly of actin filaments, and our hypothesis is that activation of cofilin by SerB is required for P. gingivalis entry. This will be tested through up and down regulation of cofilin activity by siRNA and transfections with activation-altered cofilin. Secondly, we shall determine the signaling pathways modulated by SerB that converge on suppression of the chemokine IL-8. The participation of MEK and NF-?B will be investigated by blotting, mobility shift assays and dominant positive and negative mutations. Finally, we shall characterize the interconnectivity between SerB-induced cytoskeletal signaling and IL-8 suppression, by manipulation of actin filament structure and MEK activation status. These studies will provide a detailed molecular analysis of the targeting of host signal transduction by a specific effector phosphatase of P. gingivalis. Ultimately, the knowledge gained could be developed into strategies that could be utilized to intervene in the P. gingivalis-epithelial cell interaction to ensure that the outcome is non-harmful to the host.

Public Health Relevance

P. gingivalis is a cause of periodontal diseases that afflict millions of Americans. In this study we will examine the interactions between P. gingivalis and the human cells that are colonized by the organism. The information to be gathered could be used to identify targets for novel therapeutic agents designed to interfere with the colonization and survival strategies of P. gingivalis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DE011111-20
Application #
8400390
Study Section
Special Emphasis Panel (ZRG1-MOSS-B (02))
Program Officer
Lunsford, Dwayne
Project Start
1995-04-01
Project End
2013-12-31
Budget Start
2013-01-01
Budget End
2013-12-31
Support Year
20
Fiscal Year
2013
Total Cost
$335,195
Indirect Cost
$111,732
Name
University of Louisville
Department
Psychology
Type
Schools of Public Health
DUNS #
057588857
City
Louisville
State
KY
Country
United States
Zip Code
40292
Edmisson, Jacob S; Tian, Shifu; Armstrong, Cortney L et al. (2018) Filifactor alocis modulates human neutrophil antimicrobial functional responses. Cell Microbiol 20:e12829
Lee, Jae Y; Miller, Daniel P; Wu, Leng et al. (2018) Maturation of the Mfa1 Fimbriae in the Oral Pathogen Porphyromonas gingivalis. Front Cell Infect Microbiol 8:137
Sztukowska, Maryta N; Dutton, Lindsay C; Delaney, Christopher et al. (2018) Community Development between Porphyromonas gingivalis and Candida albicans Mediated by InlJ and Als3. MBio 9:
Inaba, Hiroaki; Amano, Atsuo; Lamont, Richard J et al. (2018) Cell Cycle Arrest and Apoptosis Induced by Porphyromonas gingivalis Require Jun N-Terminal Protein Kinase- and p53-Mediated p38 Activation in Human Trophoblasts. Infect Immun 86:
Miller, Daniel P; Hutcherson, Justin A; Wang, Yan et al. (2017) Genes Contributing to Porphyromonas gingivalis Fitness in Abscess and Epithelial Cell Colonization Environments. Front Cell Infect Microbiol 7:378
Jimenez Flores, E; Tian, S; Sizova, M et al. (2017) Peptoanaerobacter stomatis Primes Human Neutrophils and Induces Granule Exocytosis. Infect Immun 85:
Glowczyk, Izabela; Wong, Alicia; Potempa, Barbara et al. (2017) Inactive Gingipains from P. gingivalis Selectively Skews T Cells toward a Th17 Phenotype in an IL-6 Dependent Manner. Front Cell Infect Microbiol 7:140
Armstrong, Cortney L; Miralda, Irina; Neff, Adam C et al. (2016) Filifactor alocis Promotes Neutrophil Degranulation and Chemotactic Activity. Infect Immun 84:3423-3433
Hajishengallis, George; Lamont, Richard J (2016) Dancing with the Stars: How Choreographed Bacterial Interactions Dictate Nososymbiocity and Give Rise to Keystone Pathogens, Accessory Pathogens, and Pathobionts. Trends Microbiol 24:477-489
Yin, Hui; Zhou, Huaxin; Kang, Yi et al. (2016) Syk negatively regulates TLR4-mediated IFN? and IL-10 production and promotes inflammatory responses in dendritic cells. Biochim Biophys Acta 1860:588-98

Showing the most recent 10 out of 55 publications