A challenge to establish a model for inducing carcinogenesis and thrombus formation by continuous endovascular inoculation of oral bacteria.

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K19637
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 57:Oral science and related fields
• Research Institution: Tokyo Medical and Dental University
• Principal Investigator: AOKI Kazuhiro 東京医科歯科大学, 大学院医歯学総合研究科, 教授 (40272603)
• Co-Investigator(Kenkyū-buntansha): 泉福 英信 国立感染症研究所, 細菌第一部, 室長 (20250186)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 慢性炎症 / Streptococcus mutans / 口腔内常在菌 / 肝臓 / 腎臓 / 顎下腺 / 骨密度 / 骨形成

Outline of Final Research Achievements

Chronic inflammation is shown to be a trigger of malignant transformation. Bacteria in the oral cavity enter the blood due to various causes. Twelve-week-old male BALB/c mice were used to clarify whether the oral bacterium causes chronic inflammation. Time-course studies of histological changes in the liver after endovascular inoculation of Streptococcus mutans were performed.
As a result, acute inflammation was caused on the 1st day after the inoculation of the bacterium. However, the infiltration of lymphocytes, which is a chronic inflammation marker, gradually increased. On the 28th day after the endovascular inoculation, the rate of lymphocytes in the region the infiltrating cells showed a significant increase compared to that on day 1. These results suggest that exposure to Streptococcus mutans may cause chronic inflammation of tissues.

Free Research Field

口腔基礎工学

Academic Significance and Societal Importance of the Research Achievements

口腔内細菌叢の乱れが、全身健康を脅かすことが明らかになってきているが、この実験では、一つの菌と全身健康との関連を調べた。
血管を介した口腔内細菌の全身暴露が、癌化の一要因とされる慢性炎症を引き起こしたことは、常在菌であっても、いったん血管を介して体内に入れば、生体組織に生菌が定着し、炎症を引き起こし、慢性化させる可能性があることを示唆している。これらの研究結果は、歯科医療の重要性を社会に示す一つのエビデンスとなる。