In this study, we report that an acute phase reactant, serum amyloid A (SAA), strongly inhibits dendritic cell differentiation induced by GM-CSF plus IL-4. SAA markedly decreased the expression of MHCII and CD11c. Moreover, SAA decreased cell surface GM-CSF receptor expression. SAA also decreased the expression of PU.1 and C/EBPα, which play roles in the expression of GM-CSF receptor. This inhibitory response by SAA is partly mediated by the well-known SAA receptors, Toll-like receptor 2 and formyl peptide receptor 2. Taken together, we suggest a novel insight into the inhibitory role of SAA in dendritic cell differentiation.
Dendritic Cells* ; Granulocyte-Macrophage Colony-Stimulating Factor* ; Interleukin-4 ; Receptors, Formyl Peptide ; Receptors, Granulocyte-Macrophage Colony-Stimulating Factor* ; Serum Amyloid A Protein* ; Toll-Like Receptors

When mouse bone marrow-derived macrophages were stimulated with serum amyloid A (SAA), which is a major acute-phase protein, there was strong inhibition of osteoclast formation induced by the receptor activator of nuclear factor kappaB ligand. SAA not only markedly blocked the expression of several osteoclast-associated genes (TNF receptor-associated factor 6 and osteoclast-associated receptor) but also strongly induced the expression of negative regulators (MafB and interferon regulatory factor 8). Moreover, SAA decreased c-fms expression on the cell surface via shedding of the c-fms extracellular domain. SAA also restrained the fusion of osteoclast precursors by blocking intracellular ATP release. This inhibitory response of SAA is not mediated by the well-known SAA receptors (formyl peptide receptor 2, Toll-like receptor 2 (TLR2) or TLR4). These findings provide insight into a novel inhibitory role of SAA in osteoclastogenesis and suggest that SAA is an important endogenous modulator that regulates bone homeostasis.
Adenosine Triphosphate/metabolism ; Animals ; Cell Differentiation ; Cell Line ; Gene Expression Regulation, Developmental ; Humans ; Macrophages/*cytology/metabolism ; Mice ; Osteoclasts/*cytology/metabolism ; RANK Ligand/*metabolism ; Receptor, Macrophage Colony-Stimulating Factor/genetics ; Receptors, Formyl Peptide/metabolism ; Serum Amyloid A Protein/*metabolism ; Toll-Like Receptor 2/metabolism ; Toll-Like Receptor 4/metabolism

Extracellular nicotinamide adenine dinucleotide (NAD) cleaving activity of a particular cell type determines the rate of the degradation of extracellular NAD with formation of metabolites in the vicinity of the plasma membrane, which has important physiological consequences. It is yet to be elucidated whether intact human neutrophils have any extracellular NAD cleaving activity. In this study, with a simple fluorometric assay utilizing 1,N6-ethenoadenine dinucleotide (etheno-NAD) as the substrate, we have shown that intact peripheral human neutrophils have scant extracellular etheno-NAD cleaving activity, which is much less than that of mouse bone marrow neutrophils, mouse peripheral neutrophils, human monocytes and lymphocytes. With high performance liquid chromatography (HPLC), we have identified that ADP-ribose (ADPR) is the major extracellular metabolite of NAD degradation by intact human neutrophils. The scant extracellular etheno-NAD cleaving activity is decreased further by N-formyl-methionine-leucine-phenylalanine (fMLP), a chemoattractant for neutrophils. The fMLP-mediated decrease in the extracellular etheno-NAD cleaving activity is reversed by WRW4, a potent FPRL1 antagonist. These findings show that a much less extracellular etheno-NAD cleaving activity of intact human neutrophils compared to other immune cell types is down-regulated by fMLP via a low affinity fMLP receptor FPRL1.
Adenosine Diphosphate Ribose ; Animals ; Bone Marrow ; Cell Membrane ; Chromatography, Liquid ; Humans ; Lymphocytes ; Mice ; Monocytes ; NAD* ; Neutrophils* ; Receptors, Formyl Peptide

In this study, we examined the therapeutic effects of an immune-stimulating peptide, WKYMVm, in ulcerative colitis. The administration of WKYMVm to dextran sodium sulfate (DSS)-treated mice reversed decreases in body weight, bleeding score and stool score in addition to reversing DSS-induced mucosa destruction and shortened colon. The WKYMVm-induced therapeutic effect against ulcerative colitis was strongly inhibited by a formyl peptide receptor (FPR) 2 antagonist, WRWWWW, indicating the crucial role of FPR2 in this effect. Mechanistically, WKYMVm effectively decreases intestinal permeability by stimulating colon epithelial cell proliferation. WKYMVm also strongly decreases interleukin-23 and transforming growth factor-beta production in the colon of DSS-treated mice. We suggest that the potent immune-modulating peptide WKYMVm and its receptor FPR2 may be useful in the development of efficient therapeutic agents against chronic intestinal inflammatory diseases.
Adjuvants, Immunologic/pharmacology/*therapeutic use ; Animals ; Caco-2 Cells ; Cell Proliferation ; Colitis, Ulcerative/*drug therapy/metabolism ; Colon/pathology ; Humans ; Interleukin-23/genetics/metabolism ; Intestinal Mucosa/drug effects/metabolism/pathology ; Mice ; Mice, Inbred C57BL ; Oligopeptides/pharmacology/*therapeutic use ; Permeability ; Receptors, Formyl Peptide/antagonists & inhibitors ; Transforming Growth Factor beta/genetics/metabolism

Neutrophils play a key role in innate immunity, and the identification of new stimuli that stimulate neutrophil activity is a very important issue. In this study, we identified three novel peptides by screening a synthetic hexapeptide combinatorial library. The identified peptides GMMWAI, MMHWAM, and MMHWFM caused an increase in intracellular Ca2+ in a concentration-dependent manner via phospholipase C activity in human neutrophils. The three peptides acted specifically on neutrophils and monocytes and not on other non-leukocytic cells. As a physiological characteristic of the peptides, we observed that the three peptides induced chemotactic migration of neutrophils as well as stimulated superoxide anion production. Studying receptor specificity, we observed that two of the peptides (GMMWAI and MMHWFM) acted on formyl peptide receptor (FPR)1 while the other peptide (MMHWAM) acted on FPR2. Since the three novel peptides were specific agonists for FPR1 or FPR2, they might be useful tools to study FPR1- or FPR2-mediated immune response and signaling.
Animals ; Calcium/metabolism ; Cell Line ; Cells, Cultured ; Chemotaxis, Leukocyte/drug effects ; Humans ; Mice ; NIH 3T3 Cells ; Neutrophils/*cytology/*drug effects ; PC12 Cells ; Peptides/*pharmacology ; Rats ; Receptors, Formyl Peptide/agonists

The present study was aimed to investigate the pathways, by which IL-27 regulates the expression of adherent molecule Mac-1, chemotactic factor receptor fMLP-R and pro-inflammatory cytokine IL-1beta in human neutrophils. Highly purified human neutrophils were isolated from peripheral blood using Ficoll-Hypaque gradients centrifugation and erythrocyte lysis. The mRNA expression of IL-27 receptor components (WSX-1/TCCR and gp130) in human neutrophils was detected by reverse transcription polymerase chain reaction (RT-PCR). After incubation with IL-27 and specific inhibitors (p38 MAPK inhibitor SB203580, PI3K inhibitor LY294002 and ERK inhibitor U0126), the mRNA levels of fMLP-R and IL-1beta were determined by real time RT-PCR, and the adherent molecule Mac-1 expression in human neutrophils was determined by flow cytometry. The IL-1beta level in culture supernatant of human neutrophils was assayed by radioimmunoassay. The results showed that IL-27 receptor components (WSX-1/TCCR and gp130) were constitutively expressed in human neutrophils. IL-27 down-regulated Mac-1 expression in human neutrophils (p<0.05). After incubation with specific inhibitors, SB203580, not LY294002 and U0126, inhibited the down-regulation of Mac-1 expression by IL-27. However, IL-27 up-regulated the mRNA expression of fMLP-R and IL-1beta, and increased the release of IL-1beta (p<0.05). Interestingly, LY294002, not SB203580 and U0126, inhibited the up-regulation of fMLP-R and IL-1beta by IL-27. It is concluded that the IL-27 may regulate the expression of Mac-1, fMLP-R and IL-1beta in human neutrophils through p38 MAPK and PI3K signal pathways.
Butadienes ; pharmacology ; Chromones ; pharmacology ; Down-Regulation ; Humans ; Imidazoles ; pharmacology ; Interleukin-1beta ; metabolism ; Interleukins ; metabolism ; Macrophage-1 Antigen ; metabolism ; Morpholines ; pharmacology ; Neutrophils ; metabolism ; Nitriles ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Pyridines ; pharmacology ; Receptors, Formyl Peptide ; metabolism ; Signal Transduction ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases ; metabolism

In this study, we observed that lysophosphatidylglycerol (LPG) completely inhibited a formyl peptide receptor like-1 (FPRL1) agonist (MMK-1)-stimulated chemotactic migration in human phagocytes, such as neutrophils and monocytes. LPG also dramatically inhibited IL-1beta production by another FPRL1 agonist serum amyloid A (SAA) in human phagocytes. However, LPG itself induced intracellular calcium increase and superoxide anion production in human phagocytes. Keeping in mind that phagocytes migration and IL-1beta production by FPRL1 are important for the induction of inflammatory response, our data suggest that LPG can be regarded as a useful material for the modulation of inflammatory response induced by FPRL1 activation.
Chemotaxis, Leukocyte/*drug effects ; Humans ; Interleukin-1beta/*biosynthesis ; Lysophospholipids/*pharmacology ; Monocytes/drug effects/immunology/metabolism/physiology ; Neutrophils/drug effects/immunology/metabolism/physiology ; Peptides/metabolism/pharmacology ; *Phagocytes/drug effects/immunology/metabolism/physiology ; Receptors, Formyl Peptide/*metabolism ; Receptors, Lipoxin/*metabolism ; Serum Amyloid A Protein/metabolism/pharmacology

Animals ; Apoptosis ; Cell Cycle ; Cell Differentiation ; Cell Proliferation ; Connexin 43 ; metabolism ; Humans ; Neoplasm Invasiveness ; pathology ; physiopathology ; Neoplasms ; metabolism ; pathology ; physiopathology ; Neoplastic Stem Cells ; metabolism ; pathology ; physiology ; Neovascularization, Pathologic ; metabolism ; pathology ; physiopathology ; Receptors, CXCR4 ; metabolism ; Receptors, Formyl Peptide ; metabolism ; Vascular Endothelial Growth Factor A ; metabolism

Serum amyloid A (SAA) has been regarded as an important mediator of inflammatory responses. The effect of several formyl peptide receptor-like 1 (FPRL1) ligands on the production of IL-8 by SAA was investigated in human neutrophils. Among the ligands tested, LL-37 was found to specifically inhibit SAA-induced IL-8 production in transcriptional and post-transcriptional levels. Since SAA stimulated IL-8 production via ERK and p38 MAPK in human neutrophils, we tested the effect of LL-37 on SAA induction for these two MAPKs. LL-37 caused a dramatic inhibition of ERK and p38 MAPK activity, which is induced by SAA. LL-37 was also found to inhibit SAA-stimulated neutrophil chemotactic migration. Further, the LL-37-induced inhibitory effect was mediated by FPRL1. Our findings indicate that LL-37 is expected to be useful in the inhibition of SAA signaling and for the development of drugs against SAA-related inflammatory diseases.
Animals ; Antimicrobial Cationic Peptides/*pharmacology ; Cell Line, Tumor ; Cell Movement ; Chemotaxis, Leukocyte ; Humans ; Interleukin-8/*biosynthesis ; MAP Kinase Kinase Kinases/metabolism ; Neutrophils/drug effects/*immunology ; Proto-Oncogene Proteins/metabolism ; Rats ; Receptors, Formyl Peptide/metabolism ; Receptors, Lipoxin/metabolism ; Serum Amyloid A Protein/*antagonists & inhibitors ; Signal Transduction ; Transcription, Genetic

Serum amyloid A (SAA) has been regarded as an important mediator of inflammatory responses. The effect of several formyl peptide receptor-like 1 (FPRL1) ligands on the production of IL-8 by SAA was investigated in human neutrophils. Among the ligands tested, LL-37 was found to specifically inhibit SAA-induced IL-8 production in transcriptional and post-transcriptional levels. Since SAA stimulated IL-8 production via ERK and p38 MAPK in human neutrophils, we tested the effect of LL-37 on SAA induction for these two MAPKs. LL-37 caused a dramatic inhibition of ERK and p38 MAPK activity, which is induced by SAA. LL-37 was also found to inhibit SAA-stimulated neutrophil chemotactic migration. Further, the LL-37-induced inhibitory effect was mediated by FPRL1. Our findings indicate that LL-37 is expected to be useful in the inhibition of SAA signaling and for the development of drugs against SAA-related inflammatory diseases.
Animals ; Antimicrobial Cationic Peptides/*pharmacology ; Cell Line, Tumor ; Cell Movement ; Chemotaxis, Leukocyte ; Humans ; Interleukin-8/*biosynthesis ; MAP Kinase Kinase Kinases/metabolism ; Neutrophils/drug effects/*immunology ; Proto-Oncogene Proteins/metabolism ; Rats ; Receptors, Formyl Peptide/metabolism ; Receptors, Lipoxin/metabolism ; Serum Amyloid A Protein/*antagonists & inhibitors ; Signal Transduction ; Transcription, Genetic