The impaired immune function and structural integrity by dietary iron deficiency or excess in gill of fish after infection with Flavobacterium columnare: Regulation of NF-κB, TOR, JNK, p38MAPK, Nrf2 and MLCK signalling
The impaired immune function and structural integrity by dietary iron deficiency or excess in gill of fish after infection with Flavobacterium columnare: Regulation of NF-κB, TOR, JNK, p38MAPK, Nrf2 and MLCK signalling
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DOI：
10.1016/j.fsi.2018.01.027
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发表时间：
2018-03-01
影响因子：
4.7
通讯作者：
Feng, Lin
中科院分区：
文献类型：
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作者：
Guo, Yan-Lin;Wu, Pei;Feng, Lin
本研究旨在探讨铁对草鱼幼鱼免疫功能和鳃结构完整性的影响及其可能机制。试验用草鱼630尾（242.32 ± 0.58 g），分别饲喂铁水平为12.15（基础日粮）、35.38、63.47、86.43、111.09、136.37和73.50 mg/kg的日粮，试验期60 d。采用柱状黄杆菌（Flavobacterium columnare）感染草鱼幼鱼，研究饲料铁对草鱼幼鱼鳃免疫功能和结构完整性的影响。结果表明：与适宜铁水平相比，缺铁降低了溶菌酶（LZ）和酸性磷酸酶（ACP）活性，降低了补体C3、C4和免疫球蛋白M（IgM）含量，降低了抗菌肽、抗炎细胞因子的mRNA水平（IL-4/13 B除外）、κ B α抑制剂（I κ B α）、雷帕霉素靶标（TOR）和核糖体蛋白S6激酶1（S6 K1）。与此相反，铁缺乏可上调幼草鱼鳃中促炎细胞因子（IL-6和IFN-γ（2）除外）、核因子κ B p65（NF-kappa Bp 65）、I κ B激酶a（IKK）、IKK β、IKK γ、eIF 4 E结合蛋白1（4 E-BP 1）和4 E-BP 2的mRNA水平，表明铁缺乏可损害鱼鳃的免疫功能。其次，缺铁下调凋亡抑制蛋白（IAP）和髓系细胞白血病1（Mcl-1）的mRNA水平，降低抗氧化酶的活性和mRNA水平，下调NF-E2相关因子2（Nrf 2）和紧密连接蛋白的mRNA水平（claudin-12和claudin-15除外），同时增加丙二醛（MDA）、蛋白质羰基（PC）和活性氧（ROS）含量。缺铁还上调半胱氨酸天冬氨酸蛋白酶（caspase）-2、-7、-8、-9、Fas配体（FasL）、凋亡蛋白酶激活因子-1（Apaf-1）、B细胞淋巴瘤-2相关X蛋白（Bax）、p38丝裂原活化蛋白激酶（p38 MAPK）、Kelch样ECH相关蛋白（Keap）1a、Keap 1b、claudin-12、-15和MLCK的mRNA水平，表明铁缺乏会影响鱼类鳃的结构完整性。第三，铁过量损害草鱼幼鱼鳃的免疫功能和结构完整性。富马酸亚铁对草鱼幼鱼的促生长效果优于硫酸亚铁。根据抗烂鳃能力、鳃中ACP活性和MDA含量估算出草鱼幼鱼的铁需要量分别为76.52、80.43和83.17mg/kg。
The aim of this study was to investigate the effects and potential mechanisms of dietary iron on immune function and structural integrity in gill of young grass carp (Ctenopharyngodon idella). A total of 630 grass carp (242.32 +/- 0.58 g) were fed diets containing graded levels of iron at 12.15 (basal diet), 35.38, 63.47, 86.43, 111.09, 136.37 and 73.50 mg/kg for 60 days. Subsequently, a challenge test was conducted by infection with Flavobacteriurn columnare to investigate the effects of dietary iron on gill immune function and structural integrity in young grass carp. First, the results indicated that compared with the optimal iron level, iron deficiency decreased lysozyme (LZ) and acid phosphatase (ACP) activities, complement 3 (C3), C4 and immunoglobulin M (IgM) contents, and down-regulated the mRNA levels of antibacterial peptides, anti-inflammatory cytokines (except IL-4/13B), inhibitor of kappa B alpha (I kappa B alpha), target of rapamycin (TOR) and ribosomal protein S6 kinase 1 (S6K1). In contrast, iron deficiency up-regulated the mRNA levels of pro-inflammatory cytokines (except IL-6 and IFN-gamma(2)), nuclear factor kappa B p65 (NF-kappa Bp65), I kappa B kinases a (IKK), IKK beta, IKK gamma, eIF4E-binding protein 1 (4E-BP1) and 4E-BP2 in gill of young grass carp, indicating that iron deficiency could impair immune function in fish gill. Second, iron deficiency down-regulated the mRNA levels of inhibitor of apoptosis protein (IAP) and myeloid cell leukemia 1 (Mcl-1), decreased activities and mRNA levels of antioxidant enzymes, down-regulated the mRNA levels of NF-E2-related factor 2 (Nrf2) and tight junction proteins (except claudin-12 and -15), and simultaneously increased malondialdehyde (MDA), protein carbonyl (PC) and reactive oxygen species (ROS) contents. Iron deficiency also up-regulated mRNA levels of cysteinyl aspartic acid-protease (caspase) -2, -7, -8, -9, Fas ligand (FasL), apoptotic protease activating factor-1 (Apaf-1), B-cell-lymphoma-2 associated X protein (Bax), p38 mitogen-activated protein kinase (p38MAPK), Kelch-like ECH-associating protein (Keap) 1a, Keap1b, claudin-12, -15 and MLCK, indicating that iron deficiency could disturb the structural integrity of gill in fish. Third, iron excess impaired immune function and structural integrity in gill of young grass carp. Forth, there was a better effect of ferrous fumarate than ferrous sulfate in young grass carp. Finally, the iron requirements based on ability against gill rot, ACP activity and MDA content in gill of young grass carp were estimated to be 76.52, 80.43 and 83.17 mg/kg, respectively.