OBJECTIVELipoxin A(4) is formed by the metabolism of arachidonic acid. Anti-inflammatory and anti-proliferative effect of lipoxin A(4) has been shown in many human diseases. Recently, as a novel high affinity receptor for ligand lipoxin A(4), Lipoxin A(4) receptor-like protein (LRLP) has been identified. Currently close attention is paid to the important contribution of connective tissue growth factor (CTGF) in lung fibrosis. The purpose of the study was to transfect LRLP gene into human lung fibroblasts and investigate the mechanism of its enhancing antagonistic effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by connective tissue growth factor.

METHODSEukaryocytic expression vector pEGFP/LRLP which contained LRLP and green fluorescence protein fusion gene (GFP) was constructed and transfected into human lung fibroblasts (HLF). After selecting with G418, HLF/LRLP cell clone which stably expressed LRLP/GFP fusion protein was isolated and characterized by the laser scanning confocal microscope. Cultured HLF and HLF/LRLP were stimulated for 24 h with CTGF (1 microg/ml) in the presence and absence of pretreatment of Lipoxin A(4) (10.0 nmol/L) for 30 min. Inhibition of cell proliferation was determined by MTT assay. Cell cycle analysis was performed by flow cytometry. Western blot was used to detect the expression of cyclin D(1) protein. Electrophoretic mobility shift assay (EMSA) was employed to detect the DNA binding activity of STAT(3).

RESULTS(1) HLF/LRLP cell clone which stably expressed LRLP and GFP fusion protein was successfully obtained. (2) Proliferation of HLF and HLF/LRLP was induced by 1 microg/ml CTGF. Pretreatment with 10 nm Lipoxin A(4) inhibited the proliferation of HLF and HLF/LRLP. And the inhibitory rate of HLF/LRLP was significantly higher than that of HLF [(54.1 +/- 4.2)%, (21.2 +/- 3.7)%, P < 0.05]. (3) The flow cytometry analysis showed that compared with HLF, more HLF/LRLP were arrested at G(0)/G(1) phase in the presence of pretreatment of Lipoxin A(4). [(76.3 +/- 3.5)%, (60.8 +/- 2.0)%, P < 0.05]. (4) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of cyclin D(1) protein expression in HLF and HLF/LRLP. And its antagonistic effect on HLR/LRLP was stronger than that on HLF (P < 0.05). (5) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of STAT(3) DNA binding activity, and its antagonistic effect on HLF/LRLP was more powerful than that on HLF (P < 0.05).

CONCLUSIONSTransfection of Lipoxin A(4) receptor-like protein gene enhanced the inhibitory effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by CTGF. Its mechanism might be related to regulation of cyclin D(1) protein expression and STAT(3) DNA binding activity.

Connective Tissue Growth Factor ; antagonists & inhibitors ; Cyclin D1 ; analysis ; DNA ; metabolism ; Fibroblasts ; cytology ; drug effects ; Humans ; Lipoxins ; pharmacology ; Lung ; cytology ; drug effects ; Receptors, Formyl Peptide ; genetics ; physiology ; Receptors, Lipoxin ; genetics ; physiology ; STAT3 Transcription Factor ; metabolism ; Transfection

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

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