ABSTRACT
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.
Subject(s)
Animals , Humans , Rats , Antimicrobial Cationic Peptides/pharmacology , Cell Line, Tumor , Cell Movement , Chemotaxis, Leukocyte , Interleukin-8/biosynthesis , MAP Kinase Kinase Kinases/metabolism , Neutrophils/drug effects , Proto-Oncogene Proteins/metabolism , Receptors, Formyl Peptide/metabolism , Receptors, Lipoxin/metabolism , Serum Amyloid A Protein/antagonists & inhibitors , Signal Transduction , Transcription, GeneticABSTRACT
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.
Subject(s)
Animals , Humans , Rats , Antimicrobial Cationic Peptides/pharmacology , Cell Line, Tumor , Cell Movement , Chemotaxis, Leukocyte , Interleukin-8/biosynthesis , MAP Kinase Kinase Kinases/metabolism , Neutrophils/drug effects , Proto-Oncogene Proteins/metabolism , Receptors, Formyl Peptide/metabolism , Receptors, Lipoxin/metabolism , Serum Amyloid A Protein/antagonists & inhibitors , Signal Transduction , Transcription, GeneticABSTRACT
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.