Flavobacteriumcolumnare感染時のイネ科コイの免疫代謝変化のセンサーと調節因子としての栄養感知シグナルの機能（英文

Nutrient sensing signaling functions as the sensor and regulator of immunometabolic changes in grass carp during Flavobacteriumcolumnare infection.

• Qian Guo
• Haiou Zheng
• Xun Liu
• Shuyan Chi
• Zhen Xu
• Qingchao Wang

抄録

細菌感染時の魚類の免疫代謝変化を説明するために、イネ科コイ（Ctenopharyngodon idellus）にFlavobacteriumcolumnare（F.columnare）を注射し、注射後6時間（hpi）から注射後7日（dpi）までの間、免疫反応、栄養代謝、関連するシグナル伝達経路を測定した。F.columnare投与後、エララメラは明らかな融合を示し、プロ炎症性サイトカインの高いmRNA発現レベルを示した。また、頭部腎臓におけるTNF-α、IL-1βおよびIL-8のmRNA発現レベルは、6 hpiおよび3 dpiで有意に上昇した。さらに、エラのIgZの発現は3dpiと7dpiで有意に上昇し、頭腎臓のIgMの発現はF.columnare注入後の1dpiと3dpiで有意に上昇した。細菌感染時には、全身の栄養代謝も有意に影響を受けた。GK mRNAの発現とPK活性で示される肝解糖は1dpiで有意に上昇し、PEPCK mRNAの発現と酵素活性で示されるグルコジェネシスはそれ以降で有意に上昇し、実験群では1dpiで肝グリコーゲン含量が減少したが、7dpiではグリコーゲン含量が増加した。脂質異化を触媒するLPLは6 hpiでmRNAの発現と酵素活性が低下したが、FA合成の速度制限を行うACCは6 hpi、3 dpi、7 dpiで有意に増加した。この間、栄養感知シグナル伝達も有意に影響を受けていた。また、イネ科コイのTORシグナル伝達が有意に活性化され、F.columnare感染後にはERKシグナル伝達が有意に抑制された。

In order to illustrate the immunometabolic changes of fish during bacterial infection, grass carp (Ctenopharyngodon idellus) was injected with Flavobacteriumcolumnare(F.columnare) and then the immune response, nutrient metabolism and related signaling pathways were assayed from 6 h post injection (hpi) to 7 days post injection (dpi). After F.columnare injection, gill lamellae showed obvious fusion and higher mRNA expression levels of pro-inflammatory cytokines. The mRNA expression levels of TNF-α, IL-1β and IL-8 in the head kidney were also significantly upregulated at 6 hpi and 3 dpi. Moreover, the expression of IgZ in the gill was significantly upregulated at 3 dpi and 7 dpi, while the expression of IgM in the head kidney was significantly upregulated at 1 dpi and 3 dpi after F.columnare injection. During bacterial infection, the systematic nutrient metabolism was also significantly affected. Hepatic glycolysis, indicated by GK mRNA expression and PK activity, was significantly upregulated at 1 dpi, while glucogenesis, indicated by PEPCK mRNA expression and enzyme activity, was significantly increased at later time, which resulted in the decreased hepatic glycogen content at 1dpi but increased glycogen content at 7 dpi in the experimental group. LPL, which catalyzed the lipid catabolism, showed decreased mRNA expression and enzyme activity at 6 hpi, while ACC, which was rate-limiting of FA synthesis, was significantly increased at 6 hpi, 3 dpi and 7 dpi. During this process, the nutrient sensing signaling was also significantly affected. TOR signaling in grass carp was significantly activated while ERK signaling was significantly inhibited after F.columnare infection, both of which might function as the sensor and regulator of fish immunometabolic changes.

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