Janina P. Lewis, Ph.D.

Janina P. Lewis, Ph.D.

Associate professor

Wood Memorial Building Link opens in new window
521 North 11th Street
Box 980566
Richmond, Virginia 23298-0566
Phone: (804) 628-7014
Fax: (804) 828-0150
Email: jplewis@vcu.edu


Education

  • Ph.D. in Microbiology and Immunology, Virginia Commonwealth University, 1997
  • M.S. in Biology, The University of Gdansk, Poland, 1990

Research

Research in our laboratory focuses on the host-pathogen interactions in the oral cavity. The main pathogens investigated are Gram-negative anaerobic bacteria implicated in development and progression of periodontal disease such as Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythensis. Both P. gingivalis and Prev. intermedia form black-pigmented colonies when grown on blood agar plates. The black pigmentation is the result of a deposition of large amounts of hemin (iron-protoporphyrin IX) on the bacterial cell surface (up to one third of the dry weight of the cell). Indeed, appropriately the name "Porphyromonas" is derived from the porphyrin that the bacterium stores.

Projects

1. Role of metals in host-pathogen interaction in oral cavity

This project involves determination and characterization of the iron and manganese uptake mechanisms in P. gingivalis and Prev. intermedia. Also, the mechanisms mediating metal homeostasis are investigated in our laboratory. So far we have identified and characterized two metal transporters, FeoB1 and FeoB2 mediating the transport of iron and manganese, respectively. These transporters also were shown to play a major role in survival of P. gingivalis in the presence of host cells. Especially the survival of P. gingivalis inside host cells was affected by mutations of the transporters. Currently, we are investigating the hemin uptake loci present in P. gingivalis.

2. Bacterial components mediating interaction with host cells

Periodontal diseases are complex chronic inflammatory conditions of tissues supporting the teeth resulting from the interaction between host and oral microflora. Microorganisms play a role in the initial stages of the diseases serving as a trigger for activation of the host inflammatory response. This involves a complex set of interactions between the host and the bacteria; however, to date, the bacterial as well as the host components mediating these interactions remain poorly understood.

An essential step in initiating the infection involves adherence to host cells by the pathogens or their products. Bacterial cell surface proteins are the first to come in contact with the host environment and are most likely mediators of this process. Although much is known about aerobic outer membrane and cell surface proteins this knowledge is sparse regarding anaerobic bacteria. Anaerobes such as Porphyromonas gingivalis, Tannerella forsythensis, and Prevotella intermedia are implicated in development of periodontal diseases. We investigate the role of cell surface proteins of the oral anaerobic bacteria in the first step of establishment of the microorganisms in the host: colonization of the oral cavity. This is accomplished using bioinformatics approaches as well as using novel combinations of cell labeling and proteomic approaches employed to identify other cell surface proteins capable of binding to host components: e.g. salivary proteins, basal membrane proteins, and host cells. These proteins are then further characterized to determine their potential to mediate the attachment of Prev. intermedia to host components.

3. Host receptors engaged in response to oral pathogens

The crucial role of the host innate response in initiation and progression of periodontal diseases has been demonstrated. Thus, to examine the molecular basis of the host response we are comprehensively characterizing the transcriptional component of the host response to challenge with live bacteria as well as its components such as adhesins and DNA using microarrays containing probes for all known genes present in the eukaryotic genome. First, to identify the cell-specific host response we are investigating the response of a variety of cell types to infection with oral pathogens.

Second, proinflammatory cytokine production is dependent on host receptors such as the Toll-like receptors (TLR) or nucleotide oligomerization domain (NOD) that have a crucial role in sensing the presence of bacterial components. Thus, we are also examining the contribution of those receptors to host response following challenge with oral bacteria. The long-term objective is to elucidate the specific host recognition mechanisms and signaling pathways engaged and activated by oral bacterial pathogens. Ultimately, we predict that this work will lead to identification of targets for the design of novel and specific therapeutic agents for treatment of periodontal diseases, and may have implications for treatment of other inflammatory diseases triggered by bacteria.

4. Adaptation of bacteria to oxidative stress

Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. It exhibits a high degree of aerotolerance and is able to survive in host cells, indicating that efficient oxidative stress protection mechanisms must be present in this organism. We are examining the contribution of a variety of mechanisms to survival of P. gingivalis with oxygen. The results of our study are expected to provide novel insights into the oxidative stress protection mechanisms in P. gingivalis. Also, we predict this work will shed light on mechanisms of oxidative stress protection in other Bacteroides-related bacteria such as Prevotella intermedia, Tannerella forsythensis, Bacteroides fragilis, B. thetaiotaomicron and Capnocytophaga hutchinsonii. So far, the oxidative stress protection mechanisms in those organisms are not well known and the regulatory mechanisms are yet to be investigated on a large scale.

5. Small non-coding RNAs in P. gingivalis

Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. Although this pathogen mainly inhabits anaerobic periodontal pockets it is also present in other niches of the oral cavity en route to the periodontal pockets as well as it can access distant parts of the body such as the cardiovascular system and heart tissues. Finally, it can invade and survive within host cells. In order to adapt to the various niches the organism is expected to have efficient regulatory mechanisms allowing it to rapidly alter gene and ultimately protein expression in response to the various challenges imposed by the various host environments. Recent reports show that small non-coding RNAs (sncRNAs) have a major role in regulation of various critical functions in several bacteria as well as in eukaryotes. So far, however, the role of sncRNAs in P. gingivalis and other anaerobic bacteria has not been investigated. It is noteworthy that analysis of the genomic sequence of P. gingivalis W83 predicted the presence of as many as 650 sncRNAs. Thus, we are verifying as well as characterizing the role of selected sncRNAs in this organism.

Publications

He J, Anaya C, He J, Miyazaki H, and Lewis JP. 2009. Identification and characterization of Prevotella intermedia 17 fibrinogen binding protein (manuscript in preparation).

Iyer D, Anaya-Bergman C, Jones K, Yanamandra S, Miyazaki H, and Lewis JP. Identification and characterization of internalin-like protein from Prevotella intermedia 17. Manuscript in review.

Anaya C, He J, Miyazaki H, Yeudall WA, and Lewis JP. 2009. The ferrous iron uptake protein FeoB1 is dispensable for oxidative stress protection and survival of Porphyromonas gingivalis in host cells. Manuscript in revision.

Maeda K, Tribble GD, Tucker CM, Anaya C, Shizukuishi S, Lewis JP, Demuth DR, and Lamont RJ. 2008. A Porphyromonas gingivalis tyrosine phosphatase is a multifunctional regulator of virulence attributes. Mol Microbiol. 69:1153-1164.

Zhang P, Lewis JP, Michalek SM, and Katz J. 2007. "Role of CD80 and CD86 in Host Immune Responses to the Recombinant Hemagglutinin Domain of Porphyromonas gingivalis Gingipain and in the Adjuvanticity of Cholera Toxin B and Monophosphoryl Lipid A". Vaccine 25: 6201-6210.

Anaya C, Church N, and Lewis JP. 2007. Detection and Identification of Bacterial Cell Surface Proteins by Fluorescent Labeling. PROTEOMICS 7:215-219.

Yu F, Iyer D, Anaya C, and Lewis JP. 2006. Identification and characterization of a cell surface protein of Prevotella intermedia 17 with broad-spectrum binding activity for extracellular matrix proteins. PROTEOMICS 6:6023-6032.

Lewis JP, Plata K, Yu F, Rosato A, and Anaya C. 2006. Transcriptional organization, regulation and role of the Porphyromonas gingivalis W83 hemin uptake (hmu) locus. Microbiology 152:3367-3382.

Yu F, Anaya C, and Lewis JP. 2006. Outer membrane proteome of Prevotella intermedia 17: Identification of thioredoxin and iron-repressible hemin uptake loci. PROTEOMICS 7:403-412.

He J, Miyazaki H, Anaya C, Yu F, Yeudall A, and Lewis JP. 2006. Role of Porphyromonas gingivalis FeoB in metal uptake and oxidative stress protection. Infection and Immunity 74:4214-4223.

Zhang P, Yang QB, Balkovetz DF, Lewis JP, Clements JD, Michalek SM, and Katz J. 2005. Effectiveness of the B subunit of cholera toxin in potentiating immune responses to the recombinant hemagglutinin/adhesin domain of the gingipain Kgp from Porphyromonas gingivalis. Vaccine 23:4734-4744.

Califano JV, Chou D, Lewis JP, Rogers JD, Best AM, and Schenkein H. 2004. Antibody reactive with Porphyromonas gingivalis hemagglutinin in chronic and generalized aggressive periodontitis. J Periodontal Res. 39:263-268.