Periodontitis is a destructive, infectious disease that has been associated with multiple fatal and debilitating chronic systemic diseases and consumes billions of dollars in health costs annually in the US. Tobacco smokers exhibit increased susceptibility to periodontitis;are more likely to be infected with the key periodontal pathogen Porphyromonas gingivalis;and to harbor higher numbers of this bacterial species relative to non-smokers. Despite this, smokers consistently exhibit reduced clinical inflammation. We show that the pro-inflammatory response of purified human monocytes is significantly suppressed when P. gingivalis is exposed to cigarette smoke extracts (CSE) and that the inflammation inducing potential of P. gingivalis is restored when cells are sub-cultured back into fresh medium without CSE. However, the influence of tobacco on the regulation of genes encoding P. gingivalis virulence determinants is essentially unknown. We hypothesize that CSE represents an environmental stress and that P. gingivalis responds by altering gene expression to adapt to this stress. We believe that this adaptive response may involve the induction of stress-related genes, virulence determinants and alterations of bacterial surface components. We also hypothesize that such cigarette smoke-induced physiological changes in P. gingivalis will include altered activities of genes encoding key pathogen recognition determinants, which will explain the reduced inflammatory response of smoke-exposed P. gingivalis. It is our aim to identify, isolate and test CSE-altered gene products in a primary human monocyte model of inflammation. Preliminary data generated through transcriptome analyses and the structural characterization of several microbial determinants are strongly supportive of our hypotheses. We have identified several genes, gene products, and bacterial structures that are dysregulated on CSE exposure that may play pivotal roles in the engagement of the innate immune system by P. gingivalis. These include fimbrial proteins, LPS, major outer membrane antigens, and other P. gingivalis components of known inflammatory potential, such as dnaJ, grpE and ragA. These studies represent a novel area of investigation and will provide some of the first information illustrating how P. gingivalis responds at the molecular level to cigarette smoke and may provide unique insights into disease pathogenesis in smokers. Thus, these studies will break new ground and provide the foundation for future studies that will elucidate mechanisms explaining how tobacco influences pathogen-host response interactions.

Public Health Relevance

The Gram negative anaerobic bacterium, Porphyromonas gingivalis, is a causative agent of chronic periodontitis, a destructive tobacco-induced and/or exacerbated disease. Smokers are more likely to be infected by P. gingivalis and to harbor higher numbers of these bacterial cells than non-smokers. However, smokers also exhibit reduced clinical inflammation and, in keeping with this, smoke-exposed P. gingivalis exhibits a reduced capacity to illicit an inflammatory response from immune cells. The mechanisms underlying this reduced inflammatory potential are entirely unknown. Therefore, we will identify P. gingivalis genes that are dysregulated by tobacco exposure by microarray analysis of P. gingivalis cultured in cigarette smoke extract (CSE)-conditioned medium. We will also examine the effects of CSE on the characteristics of cellular structures known to play critical roles in the activation of innate immune cells, such as LPS and fimbriae. The inflammatory potential of tobacco-altered bacterial structures and the products of CSE-dysregulated genes will be tested in freshly isolated human monocytes. This study will provide some of the first information illustrating how P. gingivalis responds at the molecular level to cigarette smoke and may provide unique insights into disease pathogenesis in smokers.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-MOSS-B (02))
Program Officer
Lunsford, Dwayne
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Louisville
Schools of Dentistry
United States
Zip Code
Roux, Damien; Weatherholt, Molly; Clark, Bradley et al. (2017) Immune Recognition of the Epidemic Cystic Fibrosis Pathogen Burkholderia dolosa. Infect Immun 85:
Wang, Huizhi; Graves 2nd, Mark W; Zhou, Huaxin et al. (2016) 2-Amino-4-(3,4-(methylenedioxy)benzylamino)-6-(3-methoxyphenyl)pyrimidine is an anti-inflammatory TLR-2, -4 and -5 response mediator in human monocytes. Inflamm Res 65:61-9
Hutcherson, J A; Gogeneni, H; Yoder-Himes, D et al. (2016) Comparison of inherently essential genes of Porphyromonas gingivalis identified in two transposon-sequencing libraries. Mol Oral Microbiol 31:354-64
Gu, Zhen; Lamont, Gwyneth J; Lamont, Richard J et al. (2016) Resolvin D1, resolvin D2 and maresin 1 activate the GSK3? anti-inflammatory axis in TLR4-engaged human monocytes. Innate Immun 22:186-95
Goulas, T; Garcia-Ferrer, I; Hutcherson, J A et al. (2016) Structure of RagB, a major immunodominant outer-membrane surface receptor antigen of Porphyromonas gingivalis. Mol Oral Microbiol 31:472-485
Hutcherson, J A; Bagaitkar, J; Nagano, K et al. (2015) Porphyromonas gingivalis RagB is a proinflammatory signal transducer and activator of transcription 4 agonist. Mol Oral Microbiol 30:242-52
Gogeneni, Himabindu; Buduneli, Nurcan; Ceyhan-Öztürk, Banu et al. (2015) Increased infection with key periodontal pathogens during gestational diabetes mellitus. J Clin Periodontol 42:506-12
Hutcherson, Justin A; Scott, David A; Bagaitkar, Juhi (2015) Scratching the surface - tobacco-induced bacterial biofilms. Tob Induc Dis 13:1
Zeller, Iris; Hutcherson, Justin A; Lamont, Richard J et al. (2014) Altered antigenic profiling and infectivity of Porphyromonas gingivalis in smokers and non-smokers with periodontitis. J Periodontol 85:837-44
Kaval, Ba?ak; Renaud, Diane E; Scott, David A et al. (2014) The role of smoking and gingival crevicular fluid markers on coronally advanced flap outcomes. J Periodontol 85:395-405

Showing the most recent 10 out of 22 publications