From chewing sticks to using twigs, hog bristles and horsehair, people have been polishing their pearly whites for millennia. Now EU scientists are investigating whether good oral hygiene can also protect us from chronic lung diseases. They’re also checking what our saliva says about our overall health.
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Did you ever think that a simple task like brushing your teeth could actually keep your lungs healthy – in addition to preventing cavities and gum disease?
The bacteria causing gum disease have already been linked to life-threatening heart illnesses for a while now. It is suspected they enter the bloodstream and travel to the heart. This would explain why some microbes from dental plaque often turn up in heart valves and heart muscle.
There is now increasing indication that gum health may be also strongly linked to lung diseases. ‘We believe that inflammatory bacteria in the mouth create pockets between the gum and tooth, break down the lining and spread to the heart and lungs,’ said Dr Randi Bertelsen at the University of Bergen in Norway.
Whether the bacteria in our mouth influence the health of our lungs and future risk of lung disease is the focus of a project that Dr Bertelsen leads. This involves hundreds of participants in a previous study (the European Community Respiratory Health Survey, ECRHS) who were monitored for respiratory health over the last two decades and who had given samples from their gums around 10 years ago.
With further research now underway under the BRuSH project, Dr Bertelsen is investigating the role played by the oral microbiome in lung disease. Her hypothesis is that oral microbiome communities dominated by bacteria will have a negative effect on the respiratory tract.
The patient journey through time may help reveal whether deteriorating dental health is indeed a preamble to lung disease, indicating that bacteria in the mouth are detrimental to lung health, or not. The patient gum samples were collected in study centres in Bergen, Norway; Tartu, Estonia; and Melbourne, Australia as part of ECRHS III. Dr Bertelsen is especially interested in asthma and chronic obstructive pulmonary disease (COPD), two incurable lung diseases.
Gum-lung health link
‘Most chronic lung diseases are characterised by inflammation, with lots of mucus, which makes it hard to breathe,’ Dr Bertelsen states. ‘This inflammation is caused by Gram-negative bacteria.’ So named because they don’t take up a violet-coloured dye (from Danish microbiologist Hans Christian Gram). BRuSH is especially interested in those bacteria.
Periodontitis, more commonly called gum disease, is a common bacterial infection that involves severe inflammation in the gums and can even destroy the jawbone supporting the teeth. It is estimated that more than half of European adults suffer from some form of periodontitis, many without realising it.
Some bacteria found in infected gum as well as heart tissue, such as Porphyromonas gingivalis and Streptococcus mutans, produce a compound known as lipid A. This comes in a range of chemical forms, one of which is especially potent at causing inflammation attributed to Gram-negative bacteria.
It is already known that patients with severe lung disease, such as COPD, often have severe gum disease too, but it is unclear which comes first. To resolve this, the BRuSH project will investigate by enrolling young patients with mild to moderate gum disease. Dentists will treat away bacteria from their mouth – the traditional treatment for periodontitis. Saliva and blood samples will be taken before and after the procedure.
‘We want to see if removing the bacteria in a relatively young population, before they have any respiratory diseases, actually improves lung function,’ said Dr Bertelsen. If removing the bacteria leads to better lung health, this will demonstrate that oral hygiene is far more important for lung health than previously thought. This would underline just how important tooth brushing, flossing between teeth, and dental visits are in young adults for their future lung health.
‘In Norway, healthcare is free, but going to the dentist is very expensive,’ said Dr Bertelsen, ‘and young adults in their 20s might not go for check-ups unless something is wrong.’ She worries that the consequences may be a build-up of bacteria that secrete toxins that are detrimental to their lung health over time and may promote lung diseases.
Will saliva tests replace blood tests?
Don’t take your saliva for granted. It says a lot about your health. As indicated, bacteria present in saliva might one day inform researchers about the future lung health, but also other diseases too. And although it is routine to take blood samples from patients, doctors in future may learn about their patient’s health simply by taking a mouth swab. The idea is for the saliva to be tested there and then, without the need for sophisticated and expensive lab tests.
‘There is an urgent need for very sensitive and simple sensors that could be used in the dentist or a doctor’s office or even a patient’s home,’ said Professor Bojan Petrovic, dental scientist at the University of Novi Sad in Serbia. This would allow more people to be tested and diagnosed, easier and faster, and thereby receive any appropriate treatment earlier.
Petrovic is involved in a research project (SALSETH) that seeks to use tiny amounts of saliva, with just a few reagents, to run fast and inexpensive tests using advances in microfluidics – the precise control of miniscule amounts of fluids in microchannels.
There are many diseases and infections where tiny drops of saliva could tell doctors about the health of their patients more rapidly and less invasively than taking a blood test and sending it for analysis. ‘Numerous viral infections such as hepatitis A, B, C; Epstein-Barr virus; and herpes virus have their detectable biomarkers in salivary samples,’ explained Prof. Petrovic. ‘Saliva serves as a valuable diagnostic fluid for the early detection of different cancers such as breast cancer, pancreatic cancer, lung and gastric cancer.’
The scientists working on the SALSETH project, which is both international and intersectoral, believe that saliva could also be used to assess the levels of the male sex hormone testosterone or the stress hormone cortisol. It could allow for easier monitoring of women on hormone replacement therapy, and it might also allow for some autoimmune conditions to be detected, including celiac disease, cystic fibrosis or Sjogren’s syndrome.
‘Saliva is frequently called the mirror of the body,’ Prof. Petrovic concluded, and it is ‘readily available and easily collected and stored.’ Advances in microfluidics and the research by scientists as part of the SALSETH project should help usher in new sensors, including ingestible sensing capsules designed to detect some diseases.
Without a doubt, your mouth is a mirror of your health. Not brushing your teeth will likely get you in trouble with the dentist – but could result in even bigger health risks. How and why remains to be seen, but the important work being carried out by EU researchers is expected to shed light on the intricate mechanisms bringing together bacteria, saliva and the origination and development of disease in different areas of our body.
Written by Anthony King
This article was originally published in Horizon, the EU Research and Innovation magazine.