Oxidative stress induced by Se-deficient high-energy diet implicates neutrophil dysfunction via Nrf2 pathway suppression in swine

// Tianshu Yang 1, * , Zeping Zhao 2, * , Tianqi Liu 1 , Ziwei Zhang 1 , Pengzu Wang 1 , Shiwen Xu 1, 3 , Xin Gen Lei 2 , Anshan Shan 1 1 Northeast Agricultural University, Harbin, P. R. China 2 Department of Animal Science, Cornell University, Ithaca, NY, USA 3 Key Laboratory of Animal Cellular and Genetic Engineering of Heilongjiang Province, Northeast Agricultural University, Harbin, China * These authors are contributed equally to this work Correspondence to: Shiwen Xu, email: shiwenxu@neau.edu.cn Xin Gen Lei, email: xl20@cornell.edu Anshan Shan, email: asshan@neau.edu.cn Keywords: high-energy, se deficiency, neutrophils, oxidative stress, Nrf2 Received: November 09, 2016      Accepted: December 27, 2016      Published: January 07, 2017 ABSTRACT The mechanism of the interaction between Se deficiency and high energy remains limited. The aim of the current study was to identify whether Se-deficient, high-energy diet can induce oxidative stress, and downregulate the Nrf2 pathway and phagocytic dysfunction of neutrophils. We detected the phagocytic activity, ROS production, protein levels of Nrf2 and Nrf2 downstream target genes, and the mRNA levels of 25 selenoproteins, heat shock proteins, and cytokines in neutrophils. Cytokine ELISA kits were used to measure the serum cytokines. The concentration of ROS was elevated ( P < 0.05) in obese swine fed on a low Se diet (less than 0.03 mg/kg Se) compared to control swine. The protein levels of Nrf2 and its downstream target genes were depressed during Se deficiency and high-energy intake. The mRNA levels of 16 selenoproteins were significantly decreased ( P < 0.05) in the Se-deficient group and Se-deficient, high-energy group compared to the control group. However, the mRNA levels of 13 selenoproteins in peripheral blood neutrophils were upregulated in high energy group, except TrxR1, SelI and SepW. In summary, these data indicated that a Se-deficient, high-energy diet inhibits the Nrf2 pathway and its regulation of oxidative stress, and prompted a pleiotropic mechanism that suppresses phagocytosis.