Research article

Subgingival bacterial colonization profiles correlate with gingival tissue gene expression

Panos N Papapanou¹ , Jan H Behle¹ , Moritz Kebschull¹ , Romanita Celenti¹ , Dana L Wolf¹ , Martin Handfield³ , Paul Pavlidis⁴ and Ryan T Demmer²

¹  Division of Periodontics, Section of Oral and Diagnostic Sciences, College of Dental Medicine, Columbia University, New York, NY, USA

²  Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA

³  Center for Molecular Microbiology and Department of Oral Biology, University of Florida, College of Dentistry, Gainsville, FL, USA

⁴  Department of Psychiatry and Center of High-Throughput Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada

author email corresponding author email

BMC Microbiology 2009, 9:221doi:10.1186/1471-2180-9-221

Published:	18 October 2009

Abstract

Background

Periodontitis is a chronic inflammatory disease caused by the microbiota of the periodontal pocket. We investigated the association between subgingival bacterial profiles and gene expression patterns in gingival tissues of patients with periodontitis. A total of 120 patients undergoing periodontal surgery contributed with a minimum of two interproximal gingival papillae (range 2-4) from a maxillary posterior region. Prior to tissue harvesting, subgingival plaque samples were collected from the mesial and distal aspects of each tissue sample. Gingival tissue RNA was extracted, reverse-transcribed, labeled, and hybridized with whole-genome microarrays (310 in total). Plaque samples were analyzed using checkerboard DNA-DNA hybridizations with respect to 11 bacterial species. Random effects linear regression models considered bacterial levels as exposure and expression profiles as outcome variables. Gene Ontology analyses summarized the expression patterns into biologically relevant categories.

Results

Wide inter-species variation was noted in the number of differentially expressed gingival tissue genes according to subgingival bacterial levels: Using a Bonferroni correction (p < 9.15 × 10^-7), 9,392 probe sets were differentially associated with levels of Tannerella forsythia, 8,537 with Porphyromonas gingivalis, 6,460 with Aggregatibacter actinomycetemcomitans, 506 with Eikenella corrodens and only 8 with Actinomyces naeslundii. Cluster analysis identified commonalities and differences among tissue gene expression patterns differentially regulated according to bacterial levels.

Conclusion

Our findings suggest that the microbial content of the periodontal pocket is a determinant of gene expression in the gingival tissues and provide new insights into the differential ability of periodontal species to elicit a local host response.