title: Origin of the phagocytic respiratory burst and its role in gut epithelial phagocytosis in a basal chordate.
abstract: The vertebrate phagocytic respiratory burst (PRB) is a highly specific and efficient mechanism for reactive oxygen species (ROS) production. This mechanism is mediated by NADPH oxidase 2 (NOX2) and used by vertebrate phagocytic leukocytes to destroy internalized microbes. Here we demonstrate the presence of the PRB in a basal chordate, the amphioxus Branchiostoma belcheri tsingtauense (bbt). We show that using the antioxidant NAC to scavenge the production of ROS significantly decreased the survival rates of infected amphioxus, indicating that ROS are indispensable for efficient antibacterial responses. Amphioxus NOX enzymes and cytosolic factors were found to colocalize in the epithelial cells of the gill, intestine, and hepatic cecum and could be upregulated after exposure to microbial pathogens. The ROS production in epithelial cell lysates could be reconstructed by supplementing recombinant cytosolic factors, including bbt-p47phox, bbt-p67phox, bbt-p47phox, and bbt-Rac; the restored ROS production could be inhibited by anti-bbt-NOX2 and anti-bbt-p67phox antibodies. We also reveal that the gut epithelial lining cells of the amphioxus are competent at bacterial phagocytosis, and there is evidence that the PRB machinery could participate in the initiation of this phagocytic process. In conclusion, we report the presence of the classical PRB machinery in nonvertebrates and provide the first evidence for the possible role of PRB in epithelial cell immunity and phagocytosis.
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Shengfeng
authors.initials: S
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Guangrui
authors.initials: G
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Xiangru
authors.initials: X
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Dongjuan
authors.initials: D
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Ruihua
authors.initials: R
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People׳s Republic of China; Beijing University of Chinese Medicine, Beijing 100029, People׳s Republic of China. Electronic address: lssxal@mail.sysu.edu.cn.
authors.forename: Anlong
authors.initials: A
authors.lastname: Xu
mesh_terms: D000818:Animals; D005775:Gastrula / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D064175:Lancelets / Q000378:metabolism / Q000502:physiology*; D019255:NADPH Oxidases / Q000378:metabolism*; D010587:Phagocytosis / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000235:genetics*
chemical_list: D017382:Reactive Oxygen Species; D019255:NADPH Oxidases
keywords: Amphioxus; Free radicals; NOX; Phagocytic respiratory burst; Phagocytosis; ROS