Leucine alters immunoglobulin a secretion and inflammatory cytokine expression induced by lipopolysaccharide via the nuclear factor-κB pathway in intestine of chicken embryos

• Published in: Animal (Cambridge, England) Vol. 12; no. 9; pp. 1903 - 1911
• Main Authors: Liu, S. Q., Wang, L. Y., Liu, G. H., Tang, D. Z., Fan, X. X., Zhao, J. P., Jiao, H. C., Wang, X. J., Sun, S. H., Lin, H.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2018; Elsevier Limited; Elsevier
• Subjects: Animal tissues; Animals; Cell growth; Chick Embryo; Chickens; Cytokines; Cytokines - metabolism; Embryos; Gene expression; Homeostasis; Immune response; Immune system; Immunoglobulin A; Immunoglobulin A - metabolism; Immunoglobulins; Inflammation; inflammatory cytokine; Interleukin 10; Interleukin 6; Interleukin 8; Intestinal Mucosa - metabolism; Intestine; Intestines; Kinases; Leucine; Leucine - physiology; Lipopolysaccharides; mammalian target of rapamycin/p70 ribosomal S6 kinase; Mammals; MAP kinase; Metabolism; NF-kappa B - physiology; NF-κB protein; nuclear factor-κB; Phosphorylation; Physiology and functional biology; Poultry; Protein kinase; Protein synthesis; Proteins; Rapamycin; Research Article; Ribonucleic acid; Ribosomal protein S6 kinase; RNA; Rodents; secretory immunoglobulin A; Signal transduction; Signaling; Specific pathogen free; Supplements; Toll-like receptors; TOR protein; Transcription; Beijing China; Grand Island New York; United States > US; China; nuclear factor-κB; leucine; inflammatory cytokine; secretory immunoglobulin A; mammalian target of rapamycin/p70 ribosomal S6 kinase
• ISSN: 1751-7311; 1751-732X
• DOI: 10.1017/S1751731117003342

The mammalian target of rapamycin (mTOR) has been shown to be involved in lipopolysaccharide (LPS)-induced immune responses in many mammal cells. Here, we suggest that the mTOR pathway is involved in the intestinal inflammatory responses evoked by LPS treatment in chicken embryos. The intestinal tissue from Specific pathogen free chick embryos was cultured in the presence of LPS for 2 h. Secretory immunoglobulin A (sIgA) concentrations, messenger RNA (mRNA) expression of cytokines, and protein levels of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), mTOR and p70 ribosomal S6 kinase (p70S6K) were determined. The results showed that LPS treatment increased sIgA concentrations in a dose-dependent manner. The mRNA levels of interleukine (IL)-6, IL-8, IL-10, tumor necrosis factor-α and Toll-like receptor (TLR) 4 were upregulated by LPS treatment (P<0.05). Lipopolysaccharide increased the phosphorylation of Jun N-terminal kinase (JNK), p38 MAPK and NF-κB (P<0.05) while decreasing the phosphorylation level of mTOR (P<0.05). Supplementation of leucine at doses of 10, 20 and 40 mM dose-dependently decreased sIgA production. Leucine supplementation at 40 mM restored the phosphorylation level of mTOR and p70S6K while suppressing the phosphorylation levels of NF-κB (P<0.05) and partially down-regulating the phosphorylation of p38 MAPK and JNK. The transcription of IL-6 was significantly decreased by leucine supplementation. These results suggested that leucine could alleviate LPS-induced inflammatory responses by down-regulating NF-κB signaling pathway and evoking mTOR/p70S6K signaling pathway, which may involve in the regulation of the intestinal immune system in chicken embryos.