Richard J. Lamont
Richard J. Lamont, PhD.
Director, Oral Health and Systemic Disease
Delta Dental Endowed Professor
Room 221B, Baxter I
502 852 2112
rich.lamont at louisville.edu
The oral cavity is a complex ecosystem that is home to a diverse assemblage of bacteria with a spectrum of pathogenic potentials. On tooth surfaces these organisms assemble into a complex multispecies biofilm community, commonly known as dental plaque. Community formation is a dynamic process involving attachment of bacteria to oral surfaces, cohesion and communication among constituent organisms, and adaptation to the biofilm environment. The composition and metabolic status of the resulting community determines whether the biofilm exists in commensal harmony with the host, or becomes a precursor to caries and periodontal disease, two of the most common bacterial diseases of humans.
Periodontal diseases are the pathological consequence of the action of gram-negative anaerobes on the cells and tissues of the periodontium. The gingival epithelial cells that line the gingival crevice constitute an interactive interface between host and bacteria. Pathogenic organisms can manipulate epithelial cell signal transduction pathways in order to direct their entry into the host cells. Intracellular bacteria remain viable and can grow and spread to other cells in the periodontal tissues ultimately disrupting cell and tissue homeostasis.
The Lamont Lab is investigating the pathogenic personality of Porphyromonas gingivalis. We are engaged in the molecular dissection of the adhesins that mediate attachment to the antecedent colonizer Streptococcus gordonii. We are also deciphering the molecular signaling and response interactions between P. gingivalis and S. gordonii that control community development. Another major aspect of the lifestyle of P. gingivalis is the encounter with gingival epithelial cells. The P. gingivalis invasins and the cellular events that accompany P. gingivalis internalization are a focus of study. P. gingivalis has a stealth-like persona, avoiding innate immune recognition and the mechanisms by which host innate immunity is dampened are being investigated. In addition, we are exploiting transcriptomic and proteomic approaches to establish the phenotype of intracellular P. gingivalis which is dramatically different from extracellular organisms.
Left panel: Images of P. gingivalis (green) inside gingival epithelial cells (red). Right panel: Image of multi-species community comprising S. gordonii (red), F. nucleatum (blue) and P. gingivalis (green). Confocal data acquired and assembled by Dr. Masae Kuboniwa now at Osaka University.
Chawla A, Hirano T, Bainbridge BW, Demuth DR, Xie H, Lamont RJ. 2010. Community signalling between Streptococcus gordonii and Porphyromonas gingivalis is controlled by the transcriptional regulator CdhR. Mol Microbiol 78:1510-1522.
Gupta S, Ghosh SK, Scott ME, Bainbridge B, Jiang B, Lamont RJ, McCormick TS, Weinberg A. 2010. Fusobacterium nucleatum-associated β-defensin inducer (FAD-I). J Biol Chem 285:36523-36531.
Bainbridge B, Verma RK, Eastman C, Yehia B, Rivera M, Moffatt C, Bhattacharyya I, Lamont RJ, Kesavalu L. 2010. Role of Porphyromonas gingivalis phosphoserine phosphatase enzyme SerB in inflammation, immune response, and induction of alveolar bone resorption in rats. Infect Immun 78:4560-4569.
Maeda K, Tribble GT, Tucker CM, Anaya C, Shizukuishi S, Lewis JP, Demuth DR, Lamont RJ. 2008. A Porphyromonas gingivalis tyrosine phosphatase is a multifunctional regulator of virulence attributes. Mol Microbiol 69:1153-1164.
Tribble GD, Mao S, James CE, Lamont RJ. 2006. A Porphyromonas gingivalis haloacid dehalogenase family phosphatase interacts with human phosphoproteins and is important for invasion. Proc Natl Acad Sci U S A 103:11027-11032.