Flavia Teles, DDS, MS, DMSc.

Biofilms are responsible for the majority of the infections affecting humans. They have been difficult to study, because of the microbial complexity of the various ecosystems and because of our inability to cultivate most of the resident taxa. Since pathogenic and beneficial bacterial taxa have been identified in the cultivated segment of the microbiota, it is likely that the uncultivated segment also harbors species associated with disease or health. The Teles lab focuses on the in vivo  investigation of the microbial ecology of the uncultivated/unrecognized segment of the microbiota in the oral cavity. We are working to determine the impact of these taxa in oral health maintenance, disease initiation and progression.

Quantification of Unrecognized and Uncultivated Bacterial Taxa in Periodontal Diseases
Periodontal diseases are infections that, in their moderate and severe forms, affect approximately 35% of US adults and lead to inflammation, bone and tooth loss. Recent data suggest a link between periodontal diseases and systemic conditions such as diabetes, respiratory diseases, heart disease, pre-term labor and low birth weight.

In the past 100 years, studies on the microbiota of the oral cavity have employed multiple techniques to uncover disease-associated and host-compatible bacterial species. Cultivable species including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia are recognized as periodontal pathogens since increased levels of these species were associated with periodontitis and the species decreased after successful periodontal therapy. Other species are associated with periodontal health or stability, including certain members of the genera Actinomyces and Streptococcus. However, such studies focused on the cultivated segment of the microbiota, which is reported to account for 55-60% of the subgingival biomass.

It is likely that the uncultivated/unrecognized segment of the microbiota harbors periodontal pathogens and beneficial species. Culture-independent molecular methods, such as cloning, have been used to identity uncultivated/unrecognized species in oral biofilms. To date based on sequence analysis of 16S rRNA clonal libraries in samples from the oral cavity; over 500 bacterial taxa have been detected of which over half have not yet been cultivated. A gap in knowledge exists regarding the impact of uncultivated/unrecognized taxa in periodontal health and disease.

Microbial differences between periodontal health and disease, and before and after periodontal therapy, can only be detected by quantifying levels of multiple bacterial species in many samples from several subjects. We have developed a quantitative high-throughput method to measure the levels of a wide range of cultivated and uncultivated taxa simultaneously in multiple individual subgingival biofilm samples. The RNA oligonucleotide quantification technique (ROQT) allows the quantitative microbial evaluation of subgingival plaque samples from periodontal health and disease. In our preliminary studies, we have begun to appreciate the different microbial profiles associated with both clinical states.

The clinical signs of periodontal diseases are the local sequela of the host-bacterial interaction in the periodontium. Hence, subgingival biofilms represent a model system to study the potential role of uncultivated/unrecognized bacterial taxa in the host-microbial interface. Samples are precisely located and easily obtained, the disease status can be accurately measured and monitored and host biomarkers can be quantified in gingival crevicular fluid taken from the same site. The study of the bacterial challenge and the associated host responses is currently conducted in collaboration with other Forsyth scientists. This work will provide unique data about the in vivo interplay between unrecognized subgingival bacterial species and the host immune response in individual periodontal sites.

The Pursuit of Relevant Uncultivated/Unrecognized Taxa
More than 200 uncultivated/unrecognized taxa might be present in the human oral environment. It is likely that only a subset of them might be abundant in periodontal health and disease and relevant to disease progression or stability. Therefore, we need to establish which of these taxa merit extensive effort in isolation and characterization. We are currently using ROQT to investigate the periodontal microbiota and guide the hunt for cultivated forms of these as yet uncultivated/unrecognized taxa. The isolation, cultivation and domestication of those taxa will permit the characterization of their physiology, virulence properties, antigenic profiles and role in periodontal ecology. It will also be possible to indicate uncultivated/unrecognized taxa that might be periodontal pathogens, as well as beneficial species. This information will provide additional targets for periodontal diagnosis, prevention and therapy and further define the nature of the microbiota required for periodontal stability and successful therapy.

Characterization of Oral Biofilms
Soft tissue surfaces account for 80% of the surfaces available for bacterial colonization in the oral cavity. Along with saliva, they represent reservoirs for bacterial colonization, including uncultivated/unrecognized taxa. We have begun to investigate the levels and distribution of these taxa the oral cavity of systemically and periodontally healthy individuals. This knowledge will shed light on the pathogenesis of different oral conditions.

Specific cultivated oral bacteria have been associated with oral cancer, which suggests that uncultivated taxa might be implicated in this disease as well. Oral diseases are common complications of Diabetes Mellitus (DM) and Inflammatory Bowel Disease (IBD). DM patients are at increased risk for the development of gingivitis and periodontitis. Aphtous stomatitis is a frequent and painful finding in IBD patients. Therefore, the bacterial content of oral surfaces and saliva may have relevant implications in both IBD and DM.

Saliva and biofilms from soft tissues surfaces are abundant, easily accessible and can be collected with minimal invasiveness. These qualities make them ideal samples for the study of the role of uncultivated/unrecognized bacteria in the oral cavity of not only healthy individuals, but also systemically compromised patients. Data generated with this approach will unveil new possibilities for diagnosis and treatment of an array of oral conditions.

Selected Publications

Teles RP and Teles FRF. (2009) Antimicrobial agents used in the control of periodontal biofilms, effective adjuncts to mechanical plaque control? Braz. Oral. Res. 23(1):39-48.

Teles F, Haffajee AD, Socransky SS. (2008) Reproducibility of curet sampling of subgingival biofilms.J. Periodontol. 79(4):705-713.

Figueredo CM, Rescala B, Teles RP, Teles FR, Fischer RG, Haffajee AD, Socransky SS, Gustafsson A. (2008) Increased interleukin-18 in gingival crevicular fluid from periodontitis patients. Oral Microbiol. Immunol. 23(2):173-176.

Teles F, Haffajee AD, Socransky SS. (2007) Multiple displacement amplification as an aid in checkerboard DNA-DNA hybridization. Oral Microbiol. Immunol. 22(2):118-125.

Brito LCN, Teles F, Teles RP, Franca EC, Ribeiro-Sobrinho AP, Haffajee AD, Socransky SS. (2007) The use of multiple displacement amplification and checkerboard DNA-DNA hybridization to examine the microbiota of endodontic infections.J. Clin. Microbiol. 47(9):3029-3049.