Chronic periodontal disease is a very common chronic condition which includes the familiar gum disease but can spread to the other supportive tissues around the tooth, potentially resulting in bone deterioration and toothloss. The disease is caused by overgrowth of harmful bacteria in plaque and tartar deposits around the gumline. Beyond its effects on oral health, individuals with chronic periodontitis are also at higher risk for cardiovascular disease, stroke, diabetes, and respiratory illnesses. In order to effectively treat periodontal disease today, we need to have a clear understanding of both the species of bacterial pathogens that cause the disease in the past and today, and how these bacteria have evolved through time. Archaeological studies have known that humans have been suffering from periodontal disease for millennia, although frequency and severity vary between geographic areas and historicalperiods. This study will investigate the genetic diversity and evolution of periodontal pathogens from five historic time periods in Yorkshire through biomolecular analyses of fossilised plaque on human skull remains. It will also examine different human immune responses over time in order to learn more about the bacteria's virulence and adaptability.
Our analyses extracted and analyzed both proteins and DNA preserved in ancient dental calculus. The results of the proteomic analysis indicate that there is considerable variation in the preservation of proteins between individuals and time periods, and abundance of human vs bacterial proteins. In particular, our project uncovered the presence of beta-lactoglobulin (BLG), a dietary milk protein, in many of our archaeological samples. The presence of BLG in dental calculus represent an novel individual skeletal marker for dairy consumption, and has important implications for the studying the emergence of dairying and the evolution of lactase persistence in the past. Based on this pilot data, we are expanding our dental calculus research to investigate the robusticity and sensitivity of this milk-consumption marker in archaeological remains. We are also continuing to examine the correspondence between the biomolecular and skeletal indicators of periodontitis progression and severity.
The initial results of the metagenomic analyses indicate that bacterial DNA is well preserved in dental calculus, and that DNA yields are sufficient to reconstruct ancient periodontal pathogen genomes. We have completed genome reconstructions for two periodontal pathogens, Tannerella forsythia and Treponema denticola, dating to the Medieval period. Both genomes are distinct from modern strains, as well as from medieval strains recovered from Germany. Our amplicon metagenomic results confirm that, in general, dental calculus represents a robust substrate for investigating ancient oral microbiomes, although the 16S variable region (V3) targeted in this project displayed significant primer bias, which compromised our ability to detect meaningful taxonomic differences between individuals. The results of this discovery are currently in review (Ziesemer et al Scientific Reports). We are continuing to explore variation in oral microbial communities through time and space using metagenomic 'shotgun' data.
Presentations and Conferences:
Prof Matthew Collins has been invited to speak about the project at National Trust Regional group York, the 41 Club, and the York ProBus club. He also presented preliminary results at the Association for Veterinary Teaching and Research Work meeting in April 2013. Dr. Camilla Speller was invited to present preliminary results at the NERC International Environmental ‘Omics Synthesis Conference in Cardiff, in September 2013 and gave a presentation at the C2D2 conference in Sept 2013 with Gavin Thomas (Co-I). Speller also presented the results of the project at a NERC sponsored Environmental Proteomics symposium in Sheffield, July 2, 2014,
Public engagement: Speller presented an overview of the project to public audiences at the Archaeology Open Day at the Washburn Heritage Centre in Fewston, May 8, 2013. She gave a talk entitled "the Yorkshire Oral Microbiome Project: Then and Now" discussing the archaeological samples from Fewston included in the C2D2 project, and then potential of dental calculus to understand past health. Speller also gave an interview on BBC Radio York's Science program related to the research output "Pathogens and host immunity in the ancient human oral cavity".
New collaborations have been developed with Prof Alistair Pike (University of Southampton) for future proteomic analysis of Neolithic populations from Britain and Central Europe, which we anticipate will lead to a future grant application. We have created new collaborations with Dr. Roman Fischer and other researchers at the University of Oxford, Nuffield Department of Medicine, as a result of our proteomic analyses conducted at their facility. Dr. Fischer is now working with our team on a new publications comparing Mass Spectrometry platforms based on raw data generated from the C2D2 project, as well as on our project examining BLG and dietary proteins entrapped in calculus.
Also as a result of C2D2 research, we have strengthened our collaborations with the University of Copenhagen (Prof Tom Gilbert, Dr. Enrico Capellini), and are currently working on a joint publication based on BLG proteins recovered in the ancient dental calculus (Warinner et al. in prep).
We have submitted a review article to the Philosophical Transactions of the Royal Society ('New Era in Paleomicrobiology: Microbiomes', authors Christina Warinner, Camilla Speller, Matthew Collins), which includes some very preliminary data from the project. The anticipated publication date is summer 2014. We intend to submit an additional publication on the BLG results in summer 2014.