Those with diabetes may end up with periodontitis, a gum infection which causes tooth loss. University of Pennsylvania researchers has found diabetes triggers changes in oral microbiome which increases inflammation and increases the risk of bone loss. Prior studies before this work did not show any evidence that diabetes affects the oral microbiome. In addition over four years ago, the European Federation of Periodontology and the American Academy of Periodontology issued a report describing how there is evidence that diabetes is linked to changes in the oral microbiome.
The University of Pennsylvania researchers collaborated with Peking University, the University of São Paulo, Sichuan University, the Federal University of Minas Gerais, and the University of Capinas. The authors consulted with the Penn Center for Musculoskeletal Diseases.
The researchers first explored the oral microbiome of diabetic mice compared to healthy mice. It was found that diabetic mice had a similar oral microbiome to healthy ones when sampled prior to developing high blood sugar levels known as hyperglycemia. Once the diabetic mice became hyperglycemic, their microbiome became different from normal mice and had a less diverse set of bacteria. The diabetic mice had periodontitis and increased levels of IL-17, a signaling molecule which plays a role in immune response and inflammation.
The results showed an association between changes in the oral microbiome and periodontitis but to better understand, the researchers transferred microorganisms from diabetic mice to normal germ-free mice that were never exposed to any microbes. These mice developed bone loss. A micro-CT scan showed 42% less bone than mice whom had received a microbial transfer from normal mice. Thus the researchers demonstrated that they were able to induce rapid bone loss characteristic of the diabetic group into a normal group of mice simply transferring the oral microbiome.
The researchers hypothesized that inflammatory cytokines, such as IL-17, played a role, and thus repeated the microbiome transfer experiments, but instead also injected the diabetic donors with an anti-IL-17 antibody prior to transfer. The mice that received microbiomes from the treated diabetic mice had much less severe bone loss compared to mice that received a microbiome transfer from mice not treated with the antibody.
The researchers feel these results show that diabetes-induced changes in the oral microbiome drive inflammatory changes that enhance bone loss in periodontitis. They also do not feel that IL-17 treatment can be effective at reducing bone loss in humans. This study underscores the importance of those suffering from diabetes to practice good glycemic control and good oral hygiene.
Reference: E Xiao and et al., Diabetes Enhances IL-17 Expression and Alters the Oral Microbiome to Increase Its Pathogenicity, Cell Host & Microbe, issue 1, vol. 22, 2017.