Porphyromonas gingivalis is a periodontal pathogen implicated in the initiation and progression of chronic periodontitis in adults. This organism produces major classes of biologically active sphingolipids, termed phosphorylated dihydroceramides and other unusual lipids. These lipids are potent inflammatory and immune cell activators. The primary goal of this proposal is to evaluate how these lipids promote bone loss associated with periodontitis. Another major goal is to understand how these lipids mediate their effects on bone through engagement of the innate immune system, specifically through Toll Receptor 2 (TLR2) engagement. Understanding how these lipids promote TLR2-dependent bone loss is relevant specifically to the reported effects of P. gingivalis on periodontal bone loss in experimental animals, and may be important in promotion of bone loss in rheumatoid arthritis associated with periodontal disease. P. gingivalis lipids contaminate diseased periodontal tissues in such a way that direct bacterial invasion does not account for the observed bacterial lipids recovered. This application proposes to quantify bacterial lipid levels in diseased tissue samples, using collisional mass spectrometry, in order to determine the appropriate types and mixtures of bacterial lipids for testing in bone cell cultures and experimental animals. Those lipids recovered in diseased periodontal tissues will be tested in cell culture for their capacity to either inhibit bone formation or activate bone resorption as reflected by specific changes in gene expression, increased secretion of bone destructive cytokines and direct activation of cells that mediate bone resorption. Furthermore, bone loss will be evaluated in vivo by administering bacterial lipids to bone surfaces, followed by evaluation of bone loss and the associated alterations in either bone forming or bone resorbing cells. Finally we will examine the role of TLR2 in these processes by comparing bacterial lipid effects in bone cells isolated from either wild type or TLR2 knockout animals or by testing lipids directly in these animals. The experiments summarized in this proposal are critical to explaining how P. gingivalis promotes bone loss in periodontal diseases and may provide another mechanistic explanation for bone loss associated with common systemic diseases such as rheumatoid arthritis.

Public Health Relevance

The periodontal pathogen Porphyromonas gingivalis is reported to promote periodontal bone loss through engagement of the innate immune system, specifically though engagement of Toll Receptor 2. This proposal is directly relevant to understanding how P. gingivalis mediates bone destruction in periodontal disease because we will show which constitutive lipids of P. gingivalis prevent bone formation and activate bone destruction and how this process is dependent on engagement of the innate immune system through TLR2.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE021055-04
Application #
8665809
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lumelsky, Nadya L
Project Start
2011-06-01
Project End
2016-05-31
Budget Start
2014-06-01
Budget End
2015-05-31
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Connecticut
Department
Dentistry
Type
Schools of Dentistry/Oral Hygn
DUNS #
City
Farmington
State
CT
Country
United States
Zip Code
06030
Olsen, Ingar; Nichols, Frank C (2018) Are Sphingolipids and Serine Dipeptide Lipids Underestimated Virulence Factors of Porphyromonas gingivalis? Infect Immun 86:
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Kanzaki, Hiroyuki; Movila, Alexandru; Kayal, Rayyan et al. (2017) Phosphoglycerol dihydroceramide, a distinctive ceramide produced by Porphyromonas gingivalis, promotes RANKL-induced osteoclastogenesis by acting on non-muscle myosin II-A (Myh9), an osteoclast cell fusion regulatory factor. Biochim Biophys Acta Mol Cell Biol Lipids 1862:452-462
Moye, Zachary D; Valiuskyte, Kornelija; Dewhirst, Floyd E et al. (2016) Synthesis of Sphingolipids Impacts Survival of Porphyromonas gingivalis and the Presentation of Surface Polysaccharides. Front Microbiol 7:1919
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Farrokhi, Vahid; Nemati, Reza; Nichols, Frank C et al. (2013) Bacterial lipodipeptide, Lipid 654, is a microbiome-associated biomarker for multiple sclerosis. Clin Transl Immunology 2:e8
Clark, Robert B; Cervantes, Jorge L; Maciejewski, Mark W et al. (2013) Serine lipids of Porphyromonas gingivalis are human and mouse Toll-like receptor 2 ligands. Infect Immun 81:3479-89
Nichols, Frank C; Bajrami, Bekim; Clark, Robert B et al. (2012) Free lipid A isolated from Porphyromonas gingivalis lipopolysaccharide is contaminated with phosphorylated dihydroceramide lipids: recovery in diseased dental samples. Infect Immun 80:860-74

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