ヒトの腸内細菌は,TΗを調節する胆酸代謝産物を生成する
Donggi Paik1, Lina Yao2, Yancong Zhang3,4
1Department of Immunology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
Nature
|March 17, 2022
まとめ
腸内細菌はTヘルパー17 (TH17) 細胞の分化を阻害する胆酸を生成する. これらの免疫調節性胆酸の濃度低下は炎症性腸疾患と関連しており,腸炎症の役割を示唆しています.
科学分野:
- 微生物学
- 免疫学
- 胃腸内科
背景:
- 腸内微生物群は 免疫ホメオスタシスの維持に 重要な役割を果たします
- 細菌は宿主免疫細胞,特にTヘルパー17 (TH17) 細胞の発達と機能に影響を与えます.
- 3-オクソリトコリック酸 (3-オクソLCA) のような胆酸代謝物は,TH17細胞の分化を調節することが知られている.
研究 の 目的:
- 3-オクソLCAおよび関連する免疫調節性胆酸の生産に責任を負う特定の腸内細菌を特定する.
- これらの胆酸がTH17細胞の分化に影響を与えるメカニズムを調査する.
- これらの胆汁酸とその生合成経路と炎症性腸疾患 (IBD) の関連性を決定する.
主な方法:
- 細菌培養と酵素測定を用いて,リトコリック酸から3オクソLCAとイソリトコリック酸 (isolithocholic acid, isoLCA) を生成する細菌を特定した.
- in vitroでTH17細胞の分化に 3- oxoLCAとisoLCAの影響を評価した.
- IBD の患者と無患者のサンプルにおける胆酸と遺伝子発現の量化レベル.
主要な成果:
- 特定されたヒトの腸内細菌とその3α-ヒドロキシステロイド脱水素酵素は,3-オクソLCAとisoLCAを合成することができる.
- 転写因子RORγtを抑制することで,TH17細胞の分化を抑制することが示された.
- IBD患者では,3 - オクソLCA,イソLCA,およびその生物合成遺伝子の濃度が著しく低下しました.
- IBD患者では,これらの胆酸レベルとTH17細胞関連遺伝子発現の逆相関が観察されました.
結論:
- 3-オクソLCAとイソLCAを含む細菌によって生成される胆酸は,TH17細胞機能の強力な阻害剤である.
- IBDにおけるこれらの免疫調節性胆酸およびその生物合成経路の減少は,保護的役割を果たすことを示唆しています.
- これらの発見は,腸内細菌,胆酸代謝,IBDのような炎症性疾患の病原性との新しい関連性を強調しています.
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