Bacterial composition analysis in colorectal tissue is affected by the degree of mucus adhesion

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K18105
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 55020:Digestive surgery-related
• Research Institution: Fujita Health University
• Principal Investigator: Tajima Yosuke 藤田医科大学, 医学部, 講師 (30757505)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 腸内細菌叢 / 大腸癌 / 粘液 / カルノア固定 / 16S rRNA遺伝子解析 / α多様性

Outline of Final Research Achievements

On the colorectal epithelium, the outer mucus layer is easily removable and colonized by commensal microbiota. In contrast, the inner mucus layer is firmly attached to the epithelium and devoid of bacteria. Although the specific bacteria penetrating the inner mucus layer can contact epithelial cells and trigger cancer development, most studies do not consider the degree of mucus adhesion at sampling. Therefore, we evaluated whether bacteria adhering to tissues could be identified by removing the outer mucus layer. This study showed three notable results. First, the loose mucus layer on tissues could be well removed by high-pressure washing with sterile saline. Second, the relative abundance of some bacteria was significantly decreased in both cancer and mucosa compared to the mucus covering those tissues. Third, the Shannon diversity index was significantly decreased in both cancer and mucosa compared to the mucus covering those tissues.

Free Research Field

下部消化管外科

Academic Significance and Societal Importance of the Research Achievements

本研究により、外粘液層と内粘液層以深を区別して細菌叢解析をを行うことの意義が示されました。内粘液層以深の検体を区別して採取することにより、癌の発生や進展に寄与する可能性がある内粘液層以深に定着する特定の細菌を同定できる可能性が示唆されました。また、癌や正常粘膜の細菌叢を解析する場合には、組織に付着する粘液の程度を考慮して解析を行うべきであることが示唆されました。