Purpose:
Adiponectin (APN), an adipocyte-derived protein, is known to have potent anti-inflammatory properties. It is present in a full length (fAPN) and a globular form (gAPN). Previous studies observed that gAPN was more potent than fAPN in decreasing inflammatory responses. Therefore, we identified a novel peptide (named YH15, Y137~H151) from gAPN and investigated its anti-inflammatory properties in lipopolysaccharide (LPS)-induced RAW264.7 cells.
Methods:
Cells were pretreated with YH15 (1μM, 10μM, 50μM), a control peptide (50μM) or dexamethasone (1μM) for 18 h, and then stimulated with 100 ng/mL LPS for 24 h. The protein levels of TNF-α, IL-6 and PGE2 in the medium were assessed with ELISA kits. LPS-stimulated NF-ΚB activation in RAW264.7 cells was examined using western blot analysis. The effects of YH15 on induction of IL-10 expression and activation of possible signaling pathways in RAW264.7 cells were determined in the absence of LPS.
Results:
Pretreatment with YH15 significantly inhibited the productions of TNF-α, IL-6 and PGE2 in LPS-induced RAW264.7 cells (Fig. 1). YH15 pretreatment dose-dependently suppressed LPS-mediated IΚBα degradation and NF-ΚB p65 nuclear translocation. In addition, we demonstrated that YH15 peptide (50μM) initially increased the release of IL-10 in RAW264.7 cells after 18 h incubation. Western blotting indicated that the peptide time-dependently increased phosphorylation of ERK 1/2 rather than P38 MAPK or JNK within 1 hour. Treatment with U0126, a selective inhibitor, abolished YH15-stimulated IL-10 induction.
Conclusions:
Taken together, YH15 probably exerts anti-inflammatory effects by stimulating the expression of IL-10 via ERK1/2 activation and subsequently suppressing pro-inflammatory mediator expressions through the down-regulation of NF-ΚB activity.
Keywords: inflammation • protein structure/function • signal transduction