Exploration of the pathogenicity of human intestinal spirochetosis

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K07034
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 49020:Human pathology-related
• Research Institution: National Defense Medical College
• Principal Investigator: OGATA Sho 防衛医科大学校(医学教育部医学科進学課程及び専門課程、動物実験施設、共同利用研究施設、病院並びに防衛, 臨床検査医学, 准教授 (00531435)
• Co-Investigator(Kenkyū-buntansha): 中西 邦昭 防衛医科大学校(医学教育部医学科進学課程及び専門課程、動物実験施設、共同利用研究施設、病院並びに防衛, 検査部, 教授 (60523115)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: ヒト腸管スピロヘータ症 / ブラキスピラ / 免疫組織化学 / 腸管免疫

Outline of Final Research Achievements

Human intestinal spirochetosis is a bacterial infectious disease involving the large intestine. Microscopic identification of bacterial aggregation on the mucosal surface on pathologic examination is a main route of detecting this disease. Using immunohistochemical methods, we have found high identification rate of the bacteria within the attached mucus (and even in the mucosal tissue) where usual HE histology could not find them. We have also found that invaded bacteria were digested by macrophages and that bacteria-derived fragments were delivered to the lymphoid tissues. It was suggested possible specific antibody production as a host reaction. Furthermore, mucosal eosinophilia was observed as a possible characteristic of human inetstinal spirochetosis. These findings revealed the presense of host reaction to bacterial mucosal invasion, and these were also evidences suggesting this bacteria could be pathogenic for human intestine.

Free Research Field

消化管感染症

Academic Significance and Societal Importance of the Research Achievements

ヒト腸管スピロヘータ症については、発見の機会となる病理学的変化が微細な変化であるため発見がしにくく症例の蓄積が行われていなかったが、蓄積された症例をもとに行った今回の検討で、発見手法の改良とともに、大腸の粘膜内での原因細菌の分布状況、免疫を担当する細胞との関連、それに伴った特徴的な組織像を見いだすことができ、病態解析を進めることができた。従来国内では稀とされたきたが、一定数が存在すると考えられ、発見手法の改良から他疾患との関与についてさらに評価が進む可能性がある。