Anti-inflammatory effect of pyroglutamyl-leucine on lipopolysaccharide-stimulated RAW 264.7 macrophages

• Published in: Life sciences (1973) 2014-11, Vol.117 (1), p.1-6
• Main Authors: Hirai, Shizuka, Horii, Sho, Matsuzaki, Yoshiaki, Ono, Shin, Shimmura, Yuki, Sato, Kenji, Egashira, Yukari
• Format: Article
• Language: English
• Subjects: Animals; Anti-Inflammatory Agents - administration & dosage; Anti-Inflammatory Agents - pharmacology; Blotting, Western; Cell Line; Dipeptides - administration & dosage; Dipeptides - pharmacology; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Inflammation; Inflammation - drug therapy; Inflammation - pathology; Inflammation Mediators - metabolism; Interleukin-6 - metabolism; Lipopolysaccharides - toxicity; Macrophage; Macrophages - drug effects; Macrophages - pathology; MAP Kinase Signaling System - drug effects; Mice; NF-kappa B - metabolism; Nitric Oxide - metabolism; Phosphorylation - drug effects; Pyroglutamyl peptide; Pyroglutamyl-leucine; Pyrrolidonecarboxylic Acid - administration & dosage; Pyrrolidonecarboxylic Acid - analogs & derivatives; Pyrrolidonecarboxylic Acid - pharmacology; Triticum aestivum; Tumor Necrosis Factor-alpha - metabolism; Wheat gluten hydrolysate
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2014.08.017

Food-derived peptides have been reported to yield a variety of health promoting activities. Pyroglutamyl peptides are contained in the wheat gluten hydrolysate. In the present study, we investigated the effect of pyroglutamyl dipeptides on the lipopolysaccharide (LPS)-induced inflammation in macrophages. RAW 264.7 macrophages were treated with LPS and various concentrations of pyroglutamyl-leucine (pyroGlu-Leu), -valine (pyroGlu-Val), -methionine (pyroGlu-Met), and -phenylalanine (pyroGlu-Phe). Cell viability/proliferation and various inflammatory parameters were measured by the established methods including ELISA and western blotting. The binding of fluorescein isothiocyanate-labeled LPS to RAW 264.7 cells was also measured fluorescently. All the tested dipeptides significantly inhibited the secretion of nitric oxide, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 from LPS-stimulated RAW 264.7 macrophages. Above all, pyroGlu-Leu inhibited the secretion of all these inflammatory mediators even at the lowest dose (200μg/ml). PyroGlu-Leu dose-dependently suppressed IκBα degradation and MAPK (JNK, ERK, and p38) phosphorylation in LPS-stimulated RAW 264.7 cells. On the other hand, it did not affect the binding of LPS to the cell surface. Our results indicated that pyroGlu-Leu inhibits LPS-induced inflammatory response via the blocking of NF-κB and MAPK pathways in RAW 264.7 macrophages.