Tag Archives: #periodontitis

New Study Shows 24-72 Hours of Poor Oral Hygiene Impacts Oral Health (Medicine)

Poor oral hygiene produces gum-disease bacteria and accelerates oral microbiome aging faster than previously thought. 

A new study shows that within 24-72 hours of the interruption of oral hygiene, there was a steep decrease in the presence of ‘good oral bacteria’ and the beneficial anti-inflammatory chemicals they are associated with. An increase of ‘bad bacteria’ typically present in the mouths of patients with periodontitis, a severe gum disease which can lead to tooth damage or loss, was also discovered. 

The research team, led by scientists from Single-Cell Center, Qingdao Institute of BioEnergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS) and Procter & Gamble Company (P&G), published their findings in the journal mBio on Mar. 9, 2021. 

The researchers asked 40 study participants with different levels of naturally occurring gingivitis to perform optimal oral hygiene for three weeks. This led to reduced gingivitis and a healthy baseline for the study. Gingivitis was then induced when their oral hygiene routine was interrupted over the course of four weeks. Restart of oral hygiene leads to recovery due to the reversible nature of gingivitis.

The researchers performed genetic analyses on the population of bacteria in the participants’ gum as it changed. Chemical analyses of the molecules produced by the bacteria were performed and immune responses of the study participants were recorded. 

Within just 24-72 hours of the cessation of oral hygiene, the researchers found there was a steep decrease in the presence of multiple Rothia species as well as the chemical betaine, which was reported to play an anti-inflammatory role in several inflammatory diseases.

In addition, there was a swift, full activation of multiple salivary cytokines – proteins and other molecules produced by immune system cells associated with inflammation. And just as the presence of the ‘good bacteria’ had declined, there was a sharp increase in the presence of the types of bacteria typically present in the mouths of patients with periodontitis even though there weren’t any symptoms of the illness yet.  

Taken together, the positive association with betaine and the negative association with gingivitis suggest that Rothia may be ‘good bacteria’ beneficial to gum health, contributing to the production of betaine in some way. 

“We also found a sudden ‘aging’ of the bacteria in the mouth,” said XU Jian, Director of Single-Cell Center at QIBEBT and senior author of the study. “Their oral microbiome had aged the equivalent of about a year in less than a month.” 

Previous studies have demonstrated that the composition of the population of oral bacteria (the oral microbiome) is a good predictor of the age of a patient. As one ages, one sees less of some species of bacteria and more of others. Older people, for example, tend to have far fewer Rothia species of bacteria.

“After only 28 days of gingivitis, we found the study participants had the ‘oral microbial age’ of those a year older,” said HUANG Shi, one investigator leading this study. 

The researchers now want to continue to study the link between Rothia, betaine and inflammation to see if they can come up with better early-stage responses to gingivitis.  

Featured image: Longitudinal multi-omics and microbiome meta-analysis identify an asymptomatic gingival state that links gingivitis, periodontitis and aging. (Image by LIU Yang)

Reference: Huang S, He T, Yue F, Xu X, Wang L, Zhu P, Teng F, Sun Z, Liu X, Jing G, Su X, Jin L, Liu J, Xu J. 2021. Longitudinal multi-omics and microbiome meta-analysis identify an asymptomatic gingival state that links gingivitis, periodontitis, and aging. mBio 12:e03281-20. https://doi.org/10.1128/mBio.03281-20.

Provided by Chinese Academy of Sciences

To Understand Periodontal Disease, Researchers Examine the Surprising Behavior of T Cells (Medicine)

In diseases characterized by bone loss—such as periodontitis, rheumatoid arthritis, and osteoporosis—there is a lot that scientists still don’t understand. What is the role of the immune response in the process? What happens to the regulatory mechanisms that protect bone?

In a paper published recently in Scientific Reports, researchers from the Forsyth Institute and the Universidad de Chile describe a mechanism that unlocks a piece of the puzzle. Looking at periodontal disease in a mouse model, scientists found that a specific type of T cell, known as regulatory T cells, start behaving in unexpected ways. These cells lose their ability to regulate bone loss and instead begin promoting inflammation.

“That is important because in many therapies analyzed in in-vivo models, researchers usually check if the number of regulatory T cells has increased. But they should check if these cells are indeed functioning,” says Dr. Carla Alvarez, a postdoctoral researcher at Forsyth and lead author of the paper.

Regulatory T cells control the body’s immune response. In periodontal disease, bone loss occurs because the body’s immune system responds disproportionately to the microbial threat, causing inflammation and destroying healthy tissue. Normally, regulatory T cells help suppress that destruction, but they appear to lose their suppressive abilities during periodontal disease.

This process is analyzed in the field of osteoimmunology, which explores the complex interactions between the immune system and bone metabolism.

“This is an interesting mechanism highlighting how bone loss is taking place in periodontal disease,” says Dr. Alpdogan Kantarci, Senior Member of Staff at Forsyth and co-author of the paper together with Dr. Rolando Vernal, Professor from the School of Dentistry at Universidad de Chile.

In the case of periodontal disease, a potential therapy targeting regulatory T cells could restore the T cells’ normal functioning, not just increase their numbers.

“Unfortunately, this is not a linear process—that’s the complicated part,” Kantarci says.

Periodontal disease is initiated by microbes in the mouth, making it all the more complex.

“The relationship between immune response and bone is not so straightforward,” says Alvarez. “There are multiple components. You have to imagine a complex network of signaling and cells that participate.” This cellular and microbial complexity is what makes the disease so difficult to study in humans. However, examining this mechanism in humans is the next step of the research, Alvarez says. The research team is planning a collaborative study to look at healthy and diseased patients, intending to observe similar mechanisms to what was seen in the animal model.

Reference: Alvarez, C., Suliman, S., Almarhoumi, R. et al. Regulatory T cell phenotype and anti-osteoclastogenic function in experimental periodontitis. Sci Rep 10, 19018 (2020). https://www.nature.com/articles/s41598-020-76038-w https://doi.org/10.1038/s41598-020-76038-w

Provided by Forsyth