title: A review of the immunomodulatory role of dietary tryptophan in livestock and poultry.
abstract: Tryptophan, a nutritionally essential amino acid, is active in the regulation of immune responses in animals. The products of tryptophan metabolism, such as indoleamine 2,3-dioxygenase, kynurenine, quinolinic acid, and melatonin, may improve immunity in an organism and induce anti-inflammatory responses. The immune tolerance processes mediated by tryptophan metabolites are not well understood. Recent studies have reported that the enzymes that break down tryptophan through the kynurenine metabolic pathway are found in numerous cell types, including immunocytes. Moreover, some tryptophan metabolites have been shown to play a role in the inhibition of T lymphocyte proliferation, elevation of immunoglobulin levels in the blood, and promotion of antigen-presenting organization in tissues. This review summarizes the effects and mechanisms of tryptophan and metabolites in immune functions in livestock and poultry. It also highlights the areas in which our understanding of the role(s) of tryptophan is incomplete and suggests possible future research that might prove of benefit to livestock and poultry producers.
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.|College of Animal Science, South China Agricultural University, Guangzhou, 510642, China.
authors: Miaomiao
authors: M
authors: Bai
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China. liuhn@isa.ac.cn.
authors: Hongnan
authors: H
authors: Liu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.
authors: Kang
authors: K
authors: Xu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.|Department of Animal Nutrition, College of Animal Science and Livestock Production, Federal University of Agriculture, Abeokuta, PMB 2240, Nigeria.
authors: Abimbola Oladele
authors: AO
authors: Oso
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330029, Jiangxi, China.|Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.
authors: Xin
authors: X
authors: Wu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.
authors: Gang
authors: G
authors: Liu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China.
authors: Myrlene Carine B
authors: MC
authors: Tossou
authors: Addiriyah Chair for Environmental Studies, Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
authors: Naif Abdullah
authors: NA
authors: Al-Dhabi
authors: Addiriyah Chair for Environmental Studies, Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
authors: Veeramuthu
authors: V
authors: Duraipandiyan
authors: College of Animal Science, South China Agricultural University, Guangzhou, 510642, China.
authors: Qianyun
authors: Q
authors: Xi
authors: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330029, Jiangxi, China. yinyulong@isa.ac.cn.|Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, 410125, Hunan, China. yinyulong@isa.ac.cn.|College of Animal Science, South China Agricultural University, Guangzhou, 510642, China. yinyulong@isa.ac.cn.
authors: Yinlong
authors: Y
authors: Yin
mesh_terms: D000821:Animal Feed; D000818:Animals; D019587:Dietary Supplements; D006801:Humans; D007113:Immunity, Innate; D056747:Immunomodulation / Q000187:drug effects*; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000276:immunology* / Q000378:metabolism; D007737:Kynurenine / Q000276:immunology / Q000378:metabolism; D058751:Livestock; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D008550:Melatonin / Q000276:immunology / Q000378:metabolism; D011200:Poultry / Q000276:immunology; D017378:Quinolinic Acid / Q000276:immunology / Q000378:metabolism; D012701:Serotonin / Q000276:immunology / Q000378:metabolism; D013552:Swine / Q000276:immunology; D014364:Tryptophan / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D012701:Serotonin; D007737:Kynurenine; D014364:Tryptophan; D017378:Quinolinic Acid; D008550:Melatonin
keywords: Immune function; Livestock; Metabolites; Poultry; Tryptophan