How poor oral hygiene may result in metabolic syndrome

Date:
December 8, 2020
Source:
Tokyo Medical and Dental University
Summary:
Researchers have identified a novel mechanism by which periodontal
disease may cause metabolic syndrome. By studying patients with
metabolic syndrome, the researchers demonstrated high antibody
titers against Porphyromonas gingivalis, the bacterium causing
periodontal disease. In a mouse model, the researchers then
showed that infection with this bacterium causes systemic insulin
resistance and metabolic dysfunction in skeletal muscle by altering
the gut microbiome. This study shows the effect periodontal disease
can have on the entire body.



FULL STORY ========================================================================== Periodontal or gum disease is known to be a significant risk factor of metabolic syndrome, a group of conditions increasing the risk for heart
disease and diabetes. In a new study, researchers from Tokyo Medical and
Dental University (TMDU) discovered that infection with Porphyromonas gingivalis, the bacterium causing periodontal disease, causes skeletal
muscle metabolic dysfunction, the precursor to metabolic syndrome,
by altering the composition of the gut microbiome.


========================================================================== Periodontal bacteria have long been known to cause inflammation within the
oral cavity, but also systemically increase inflammatory mediators. As
a result, sustained infection with periodontal bacteria can lead to
increases in body weight and lead to increased insulin resistance,
a hallmark of type 2 diabetes.

The function of insulin is to help shuttle glucose from the blood into
tissues, most importantly to skeletal muscle, where one quarter of all
glucose in stored. Unsurprisingly, insulin resistance plays a key role
in the development of metabolic syndrome, a group of conditions including obesity, altered lipid metabolism, high blood pressure, high blood glucose levels, and systemic inflammation. Although skeletal muscle plays a key
role in decreasing blood glucose levels, a direct connection between periodontal bacterial infection and the metabolic function of skeletal
muscle has not been established yet.

"Metabolic syndrome has become a widespread health problem in the
developed world," says first author of the study Kazuki Watanabe. "The
goal of our study was to investigate how periodontal bacterial
infection might lead to metabolic alterations in skeletal muscle and
thus to the development of metabolic syndrome." To achieve their goal,
the researchers first investigated antibody titers to Porphyromonas
gingivalis in the blood of patients with metabolic syndrome and found
a positive correlation between antibody titers and increased insulin resistance. These results showed that patients with metabolic syndrome
were likely to have undergone infection with Porphyromonas gingivalis
and thus have mounted an immune response yielding antibodies against the
germ. To understand the mechanism behind the clinical observation, the researchers then turned to an animal model. When they gave mice that were
fed a high-fat diet (a pre- requisite to developing metabolic syndrome) Porphyromonas gingivalis by mouth, the mice developed increased insulin resistance, and fat infiltration and lower glucose uptake in the skeletal muscle compared with mice that did not receive the bacteria.

But how was this bacterium capable of causing systemic inflammation and metabolic syndrome? To answer this question, the researchers focused
on the gut microbiome, the network of bacteria present in the gut
and with which the organism co-exists symbiotically. Intriguingly,
the researchers found that in mice administered with Porphyromonas
gingivalis the gut microbiome was significantly altered, which might
decrease insulin sensitivity.

"These are striking results that provide a mechanism underlying
the relationship between infection with the periodontal bacterium
Porphyromonas gingivalis and the development of metabolic syndrome and metabolic dysfunction in skeletal muscle," says corresponding author of
the study Professor Sayaka Katagiri.


========================================================================== Story Source: Materials provided by
Tokyo_Medical_and_Dental_University. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Kazuki Watanabe, Sayaka Katagiri, Hirokazu Takahashi, Naoki
Sasaki, Shogo
Maekawa, Rina Komazaki, Masahiro Hatasa, Yoichiro Kitajima,
Yusuke Maruyama, Takahiko Shiba, Keiji Komatsu, Yujin Ohsugi,
Kenichi Tanaka, Ayumi Matsuzawa, Tomomitsu Hirota, Haruka
Tohara, Yuichiro Eguchi, Keizo Anzai, Atsuhiko Hattori, Takanori
Iwata. Porphyromonas gingivalis impairs glucose uptake in skeletal
muscle associated with altering gut microbiota. The FASEB Journal,
2020; DOI: 10.1096/fj.202001158R ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/12/201208111428.htm

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