title: Vitamin A deficiency suppresses fish immune function with differences in different intestinal segments: the role of transcriptional factor NF-κB and p38 mitogen-activated protein kinase signalling pathways.
abstract: The present study investigated the effects of dietary vitamin A on immune function in the proximal intestine (PI), mid intestine (MI) and distal intestine (DI) of young grass carp (Ctenopharyngodon idella). Fish were fed graded levels of dietary vitamin A for 10 weeks, and then a challenge test using an injection of Aeromonas hydrophila was conducted for 14 d. The results showed that, compared with the optimum vitamin A level, vitamin A deficiency significantly decreased fish growth performance, increased enteritis morbidity, decreased intestinal innate humoral immune response and aggravated intestinal inflammation. However, liver-expressed antimicrobial peptide 2A/B mRNA in the DI and IL-6, IL-17D, IL-10, transforming growth factor (TGF)-β1 and TGF-β2 mRNA in the PI were not affected by vitamin A levels. Meanwhile, vitamin A deficiency disturbed inflammatory cytokines in the PI, MI and DI, which might be partly linked to p38 mitogen-activated protein kinase (p38MAPK) signalling and NF-κB canonical signalling pathway (IκB kinase β (IKKβ), IKKγ, inhibitor of κBα, NF-κB p65 and c-Rel) rather than NF-κB non-canonical signalling pathway (NF-κB p52 and IKKα). However, the signalling molecules NF-κB p65 and p38MAPK did not participate in regulating cytokines in the PI. These results suggested that vitamin A deficiency decreased fish growth and impaired intestinal immune function, and that different immune responses in the PI, MI and DI were mediated partly by NF-κB canonical signalling and p38MAPK signalling pathways. On the basis of percentage of weight gain, to protect fish against enteritis morbidity and acid phosphatase activity, the optimum dietary vitamin A levels were estimated to be 0·664, 0·707 and 0·722 mg /kg, respectively.
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Feng
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Wei-Dan
authors.initials: WD
authors.lastname: Jiang
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Pei
authors.initials: P
authors.lastname: Wu
authors.affiliation: 4Animal Nutrition Institute,Sichuan Academy of Animal Science,Chengdu 610066,People's Republic of China.
authors.forename: Sheng-Yao
authors.initials: SY
authors.lastname: Kuang
authors.affiliation: 4Animal Nutrition Institute,Sichuan Academy of Animal Science,Chengdu 610066,People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tang
authors.affiliation: 4Animal Nutrition Institute,Sichuan Academy of Animal Science,Chengdu 610066,People's Republic of China.
authors.forename: Wu-Neng
authors.initials: WN
authors.lastname: Tang
authors.affiliation: 5Institute of Hydrobiology,Chinese Academy of Sciences,Wuhan 430072,People's Republic of China.
authors.forename: Yong-An
authors.initials: YA
authors.lastname: Zhang
authors.affiliation: 1Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,People's Republic of China.
authors.forename: Xiao-Qiu
authors.initials: XQ
authors.lastname: Zhou
mesh_terms: D016980:Aeromonas hydrophila; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002347:Carps; D004032:Diet / Q000662:veterinary; D004751:Enteritis / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D005393:Fish Diseases / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D005786:Gene Expression Regulation; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000276:immunology* / Q000473:pathology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D014802:Vitamin A Deficiency; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D012333:RNA, Messenger; D048051:p38 Mitogen-Activated Protein Kinases
keywords: 
                 NF-κB canonical signalling; 
                 p38 Mitogen-activated protein kinase
              ;  ACP acid phosphatase;  C3 complement 3;  C4 complement 4;  DI distal intestine;  FE feed efficiency;  FI feed intake;  IFN-γ2 interferon γ2;  IKK IκB kinase;  IκB inhibitor of κB;  LA lysozyme;  LEAP liver-expressed antimicrobial peptide;  MI mid intestine;  PI proximal intestine;  PWG percentage of weight gain;  SGR specific growth rate;  TGF transforming growth factor;  cDNA complementary DNA;  p38MAPK p38 mitogen-activated protein kinase; Grass carp; Immune responses; Intestinal segments; Vitamin A deficiency