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


MAIN METHODS
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.


KEY FINDINGS
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.


SIGNIFICANCE
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.
['Hirai|Shizuka|S|', 'Horii|Sho|S|', 'Matsuzaki|Yoshiaki|Y|', 'Ono|Shin|S|', 'Shimmura|Yuki|Y|', 'Sato|Kenji|K|', 'Egashira|Yukari|Y|']
D000818:Animals D000893:Anti-Inflammatory Agents D015153:Blotting, Western D002460:Cell Line D004151:Dipeptides D004305:Dose-Response Relationship, Drug D004797:Enzyme-Linked Immunosorbent Assay D007249:Inflammation D018836:Inflammation Mediators D015850:Interleukin-6 D008070:Lipopolysaccharides D020935:MAP Kinase Signaling System D008264:Macrophages D051379:Mice D016328:NF-kappa B D009569:Nitric Oxide D010766:Phosphorylation D011761:Pyrrolidonecarboxylic Acid D014409:Tumor Necrosis Factor-alpha
Pyroglutamyl-leucine Macrophage Pyroglutamyl peptide Wheat gluten hydrolysate Inflammation