A Novel Peptide Derived from Human Pancreatitis-Associated Protein Inhibits Inflammation In Vivo and In Vitro and Blocks NF-Kappa B Signaling Pathway

Abstract

BackgroundPancreatitis-associated protein (PAP) is a pancreatic secretory protein belongs to the group VII of C-type lectin family. Emerging evidence suggests that PAP plays a protective effect in inflammatory diseases. In the present study, we newly identified a 16-amino-acid peptide (named PAPep) derived from C-type lectin-like domain (CTLD) of human PAP with potent anti-inflammatory activity using both in vivo and in vitro assays.Methodology/Principal FindingsWe assessed the anti-inflammatory effect of PAPep on endotoxin-induced uveitis (EIU) in rats and demonstrated that intravitreal pretreatment of PAPep concentration-dependently attenuated clinical manifestation of EIU rats, reduced protein leakage and cell infiltration into the aqueous humor (AqH), suppressed tumor necrosis factor (TNF)-α, interleukin (IL)-6, intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein (MCP)-1 production in ocular tissues, and improved histopathologic manifestation of EIU. Furthermore, PAPep suppressed the LPS-induced mRNA expression of TNF-α and IL-6 in RAW 264.7 cells, inhibited protein expression of ICAM-1 in TNF-α-stimulated human umbilical vein endothelial cells (HUVECs) as well as U937 cells adhesion to HUVECs. Western blot analysis in ocular tissues and different cell lines revealed that the possible mechanism for this anti-inflammatory effect of PAPep may depend on its ability to inhibit the activation of NF-kB signaling pathway.Conclusions/SignificanceOur studies provide the first evidence that the sequence of PAPep is within the critically active region for the anti-inflammatory function of PAP and the peptide may be a promising candidate for the management of ocular inflammatory diseases.

Endotoxin-neutralizing activity and mechanism of action of a cationic α-helical antimicrobial octadecapeptide derived from α-amylase of rice

“…Therefore, the results suggested the possibility that AmyI-1-18 inhibited endotoxin-induced NO production in RAW264 cells not by blocking LPS-LBP binding but by inhibiting transfer of LPS to the CD14 molecule mediated by LBP. However, we cannot rule out that the anti-inflammatory activity of AmyI-1-18 is partially dependent on the inhibition of LPS-induced phosphorylation of mitogenactivated protein kinase, p38, extracellular signal-regulating kinase 1/2, and/or c-Jun N-terminal kinase 1/2, involved in the TLR4 signal pathway because several AMPs were found to possess an ability to repress LPS-induced phosphorylation [13,16,20,55]. Further investigations are required to completely comprehend the functional interaction of AmyI-1-18 with cellular components involved in the TLR4 signal pathway.…”

“…The pro-inflammatory response through stimulation of TLR4 signaling is initiated by the binding of LPS to LBP, followed by attachment of the LPS-LBP complex to the CD14 molecule on the surface of RAW264 cells and subsequent interaction of LPS with TLR4-MD2 membrane-spanning complex [13,16,20,55]. In addition to the ability of AmyI-1-18 to tightly bind LPS and lipid A, we examined the ability of AmyI-1-18 to block LPS-LBP binding.…”

“…NO is an important inflammatory product that is primarily involved in promoting inflammatory responses [5,23,28,54,55]. To examine the effect of AmyI-1-18 on endotoxin-stimulated NO induction in RAW264 cells, the cells were treated with or without 100 ng/mL smooth-type of LPS or lipid A.…”

“…In particular, LPS is a strong stimulator of mononuclear phagocytes such as monocytes and macrophages, which are part of the innate immune system of humans and other mammals. Thus, LPS induces cellular inflammatory cytokines [interleukin (IL)-6, IL-8, tumor necrosis factor-␣] and/or nitric oxide (NO) production and their release via TLR4 signaling, leading to pyrogenic responses and the destruction of tissues and cells [5,54,55]. Therefore, LPS has been called an "endotoxin" because of its cytotoxic properties in humans and http://dx.doi.org/10.1016/j.peptides.2015.…”

PAPep, a small peptide derived from human pancreatitis-associated protein, attenuates corneal inflammation in vivo and in vitro through the IKKα/β/IκBα/NF–κB signaling pathway

“…In recent years, small peptides has aroused researchers' interests because they display potential efficacy, lower immunogenicity and sufficient penetration capability, which enables them to better target inflammation, neovascularization and tumors [6,7]. Previously, we have identified a novel peptide [8], PAPep (sequence:ASLSRSTAFLRWKDYN) from human pancreatitis-associated protein (PAP), which is known for its anti-inflammation activities against a series of diseases [9][10][11]. For the first time, we have demonstrated its protective effect against uveitis in a rat model [8].…”