Can your health be affected by what’s in your mouth?

How periodontal disease effects your oral microbiome and the implications in regards to your health and wellbeing.

Original Article: Liu Bo et al. "Deep Sequencing of the Oral Microbiome Reveals Signatures of Periodontal Disease." PLoS ONE 7.6 (2012): 1-16.

Post By: Kristyn Norris

Image from http://www.drcaplanis.com/

Ever since the first sighting by Leeuwenhoek in the seventeenth century, the world of research science has been interested in microbe environment within and on our own bodies. Using a homemade microscope Leeuwenhoek got the first look at the bacteria that live in our mouths, now referred to as our oral microbiome. Of course much more research has been done since then as well as developments in the way we look at bacteria. A huge discovery in this field relates our own oral health to our overall health. We can actually get sick because of the bacterial environment with our mouths!  Not only can bad oral hygiene cause you to get the occasional cold or two but it has been linked to long term and serious problems as cardiovascular and chronic diseases. However for as much as we know about bacteria, they is still so much we do not know including how big a role our microbiomes play in our wellbeing. 

Poor dental health can lead to many diseases such as periodontal disease, an advanced case of gingivitis or gum disease. Periodontal disease has recently been linked to many chronic illnesses such as arthritis and heart problems, especially in older people. Researchers have been speculating about which microbe in the oral microbiome is responsible for this disease for many years now and have made a few accusations. The identity of this microbe could help in treatment and prevention of periodontal disease as well as the downstream affects. The problem with this and most microbiome studies is that there are a lot of bacteria! To this date only 49% have been named and a good majority are uncultureable. They estimate that there are about 700 different microbes that make up our oral microbiome. (For more information about the attempt to identify the oral microbiome visit the human oral microbiome database, http://www.homd.org/).  In the paper Deep Sequencing of the Oral Microbiome Reveals Signatures of Periodontal Disease, Lui et al claim use deep sequencing technology to get insight into all the microbes in our mouths.

With the advances in genetic sequencing they are able to do just that, a whole-metagenomic analyses of a person’s oral microbiome. This means that they were able to sequence everything within the human mouth and used computer programs to analyze this mass amount of data. They took 16S rRNA data from five different people, two diagnosed with periodontal disease and three healthy. The16S rRNA is a chronometer for bacteria and can be used to track phenology because of the decrease rate of mutation within this sequence. Upon comparison of the entire oral genome of the 5 patients, the first thing they looked at was diversity of microbes within their own mouth and how they differed from other subjects. Others studies investigation oral health have attributed poor oral health and periodontal subjects with high levels of gram negative bacteria. They were able to come to this conclusion as well and they focused their efforts on of these gram negative bacteria. In addition they found an un-cultureable bacteria identified as TM7 which could be a novel pathogen. The assessed the TM7 and other suspicious bacteria as pathogenic based on possible virulence factors it possessed using a hybrid assembly approach. Even with a culprit in mind Lui et. all found that periodontal disease was not merely the work of one malicious bacteria but attributed to changes within the whole microbiome.

                  The microbiome comparison also lead to the discovery that the diseased subjects had higher amounts of diversity within their microbial population and both subjects’ microbiomes were very similar to each other. As for the healthy subjects, they had lower diversity in their individual microbiomes but varied person to person greatly. You can see this in figure 3 from the paper where they compare the diseased samples with the healthy ones. A shows that the diversity is much higher in those that are diseased. While B and C show you that the sick (red) are more clustered together in type and number of bacteria than the healthy (blue). D is a comparison of the frequency of the bacteria in both healthy and diseased patients. Overall this means that the diseased subjects were very similar in both the type of microbes that they have and in relatively similar amounts. As an aside during this investigation Lui et al also were able to detect from the microbial population an early stage of periodontal disease in a healthy subject which was confirmed with a dental checkup which could have implication in prevention.

                 

This article gives new ways to investigate the microbial community that inhabit our mouth. While the results are intriguing and would add beneficial knowledge to the scientific community, it must be noted that this was a preliminary trial and had a very small population size. In order for there to be a true correlation they would have to increase their numbers. I would also suggest that they weed out any early periodontal disease subjects as it may skew the data.  The importance of the research cannot be overplayed as the health and balance of this community is essential for our wellbeing throughout the body, given the fact that it is the entry way into our body. Having knowledge of and ways to detect these imbalances may help us to prevent such diseases as periodontal disease and in turn improve the quality of our lives in years to come. This may also become a method for detecting and preventing cardiovascular and other chronic diseases.  If you take care of your mouth, you take care of your body.

Reference

HOMD : Human Oral Microbiome Database. The Forsyth Institute, 2015.

Liu, Bo, Lina L. Faller, Niels Klitgord, Varun Mazumdar, Mohammad Ghodsi, Daniel D. Sommer, Theodore R. Gibbons, Todd J. Treangen, Yi-Chien Chang, Shan Li, O. Colin Stine, Hatice Hasturk, Simon Kasif, Daniel Segrè, Mihai Pop, and Salomon Amar. "Deep Sequencing of the Oral Microbiome Reveals Signatures of Periodontal Disease." PLoS ONE 7.6 (2012): 1-16.

"What Is Periodontal Disease." South County: Periodontics and Implant Dentistry. Nicholas Caplanis, 2015.