Dental Tribune International

Researchers link amoeba to severe periodontitis

BERLIN, Germany: For the first time, researchers from Charité—Universitätsmedizin Berlin have shown that the amoeba Entamoeba gingivalis, commonly found in the oral cavity, plays a role in both severe tissue inflammation and tissue destruction. Once the parasite has invaded the gingival tissue, it feeds on its cells and causes tissue destruction. According to the study findings, most patients with severe and recurrent periodontitis showed an increased presence of the unicellular organism in their oral cavities.

In Germany, approximately 15% of people are affected by a particularly severe form of periodontitis. The disease has a strong association with arthritis, cardiovascular disease and cancer. In patients with gingival disease, a decrease in the diversity of the oral flora coincides with an increase in the presence of E. gingivalis.

Scientists have long been aware of the virulence potential of this genus of amoebae. The gastro-intestinal parasite Entamoeba histolytica, for instance, causes a disease known as amebiasis, one of the most common causes of death from parasitic diseases worldwide. “We have shown that an amoeba like E. gingivalis, which colonises the oral cavity, will invade the oral mucosa and destroy gingival tissue. This enables increased numbers of bacteria to invade the host tissue, which further exacerbates inflammation and tissue destruction,” said lead researcher Prof. Arne Schäfer, head of the research department in the Department of Periodontology and Synoptic Dentistry at the Institute of Dental and Craniofacial Sciences at Charité.

The researchers are the first to describe the precise role of E. gingivalis in the pathogenesis of inflammation. During their analysis of inflamed periodontal pockets, they detected evidence of the amoeba in approximately 80% of patients with periodontitis, but in only 15% of the control group. Observations revealed that, after invading the gingivae, the parasites migrate inside the tissue, feeding on and killing host cells. Cell culture experiments showed that infection with E. gingivalis slows the rate at which cells grow, eventually leading to cell death.

“This parasite, which is transmitted by simple droplet infection, is one potential cause of severe oral inflammation”

Prof. Arne Schäfer, Charité Berlin

The researchers concluded that the amoeba’s role in inflammation shows distinct parallels to the pathogenesis of amebiasis. “E. gingivalis actively contributes to cell destruction inside the gingival tissue and stimulates the same host immune response mechanisms as E. histolytica during its invasion of the intestinal mucosa,” explained Schäfer. “This parasite, which is transmitted by simple droplet infection, is one potential cause of severe oral inflammation.”

Treatment success is often short-lived in patients with periodontitis. This might be due to the high virulence potential of this previously unnoticed, yet extremely common, amoeba. “We identified one infectious parasite whose elimination could improve treatment effectiveness and long-term outcomes in patients with gum disease,” said Schäfer. “Current treatment concepts for periodontitis fail to consider the possibility of infection by this parasite or its successful elimination,” he added. A clinical trial to determine the extent to which the elimination of this amoeba might improve treatment outcomes in patients with periodontitis is underway.

The study, titled “Entamoeba gingivalis causes oral inflammation and tissue destruction”, was published online on 5 February 2020 in the Journal of Dental Research, ahead of inclusion in an issue.

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