The present study evaluated the effects of (2-Carboxyethyl)dimethylsulfonium Bromide (Br-DMPT) supplementation on the intestinal immune function and potential mechanisms of on-growing grass carp (Ctenopharyngodon idella) by feeding fish (initial weight 216.49 ± 0.29 g) five diets with gradational Br-DMPT (0-520 mg/kg diet) concentrations for 60 days and then infecting them with Aeromonas hydrophila for 14 days. Our results firstly indicated that compared with the control group, appropriate Br-DMPT supplementation increased the number of beneficial bacteria Lactobacillus and Bifidobacterium and enteritis resistance, decreased the number of detrimental bacteria Aeromonas and E. coli, and relieved the intestinal histopathological symptoms of fish. In addition, compared with the control group, appropriate Br-DMPT supplementation (1) increased lysozyme (LZ) and acid phosphatase (ACP) activities, as well as complement 3 (C3), C4 and immunoglobulin M (IgM) content; (2) upregulated the mRNA levels of anti-microbial substance: liver expressed anti-microbial peptide (LEAP) -2A, LEAP-2B, hepcidin, β-defensin-1 and Mucin2; (3) partially downregulated the mRNA levels of pro-inflammatory cytokines [interleukin 1β (IL-1β), IL-6, IL-8, IL-12p40, IL-15, IL-17D, tumour necrosis factor α (TNF-α) and interferon γ2 (IFN-γ2)] by inhibiting [IKKβ/IκBα/(NF-κBp65 and c-Rel)] signalling; and (4) partially upregulated the mRNA levels of anti-inflammatory cytokines [IL-4/13A, IL-10, IL-11, transforming growth factor (TGF)-β1] by activating [TOR/(S6K1 and 4E-BP)] signalling. The aforementioned results indicated that appropriate amount of Br-DMPT exerted a positive effect on the regulation of intestinal immune function in fish. Finally, based on enteritis morbidity, the IgM content and the lysozyme activity in the PI, the appropriate levels of Br-DMPT supplementation for on-growing grass carp were established as 295.43, 301.73 and 320.36 mg/kg diet, respectively.

中文翻译：

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（2-羧乙基）二甲基rom溴化物（Br-DMPT）在生长的草鱼（Ctenopharyngodon idella）中对肠道免疫调节作用的新颖见解。

本研究评估了补充（2-羧乙基）二甲基溴化ulf（Br-DMPT）对饲喂鱼（初始体重216.49±0.29 g）5的草鱼（Ctenopharyngodon idella）肠道免疫功能和潜在机制的影响逐步添加Br-DMPT（0-520 mg / kg饮食）浓度的日粮60天，然后用嗜水气单胞菌感染14天。我们的结果首先表明，与对照组相比，适当补充Br-DMPT可以增加有益细菌乳杆菌和双歧杆菌的数量以及肠炎抵抗力，减少有害细菌气单胞菌和大肠杆菌的数量，并减轻鱼的肠道组织病理学症状。此外，与对照组相比，适当补充Br-DMPT（1）增加溶菌酶（LZ）和酸性磷酸酶（ACP）的活性，以及​​补体3（C3），C4和免疫球蛋白M（IgM）的含量；（2）上调抗微生物物质的mRNA水平：肝脏表达的抗微生物肽（LEAP）-2A，LEAP-2B，铁调素，β-防御素-1和粘蛋白2；（3）部分下调促炎细胞因子[白介素1β（IL-1β），IL-6，IL-8，IL-12p40，IL-15，IL-17D，肿瘤坏死因子α（TNF-α）的mRNA水平）和干扰素γ2（IFN-γ2）]，通过抑制[IKKβ/IκBα/（NF-κBp65和c-Rel）]信号传导来实现；（4）通过激活[TOR /（S6K1和4E-BP），部分上调抗炎细胞因子[IL-4 / 13A，IL-10，IL-11，转化生长因子（TGF）-β1]的mRNA水平。 ]信号。上述结果表明，适量的Br-DMPT对鱼类肠道免疫功能的调节具有积极作用。最后，根据肠炎的发病率，PI中的IgM含量和溶菌酶活性，确定生长中草鱼的Br-DMPT补充水平分别为295.43、301.73和320.36 mg / kg。