Lysophosphatidic acid inhibits CC chemokine ligand 5/RANTES production by blocking IRF-1-mediated gene transcription in human bronchial epithelial cells.
Lysophosphatidic acid (LPA) is a phospholipid mediator that exerts a variety of biological responses through specific G-protein-coupled receptors (LPA(1)-LPA(5) and P2Y5). LPA is thought to be involved in airway inflammation by regulating the expression of anti-inflammatory and proinflammatory genes. Chemokines such as CCL5/RANTES are secreted from airway epithelium and play a key role in allergic airway inflammation. CCL5/RANTES is a chemoattractant for eosinophils, T lymphocytes, and monocytes and seems to exacerbate asthma. We stimulated CCL5/RANTES production in a human bronchial epithelial cell line, BEAS-2B, with IFN-γ and TNF-α. When LPA was added, CCL5/RANTES mRNA expression and protein secretion were inhibited, despite the presence of IFN-γ and TNF-α. The LPA effect was attenuated by Ki16425, a LPA(1)/LPA(3) antagonist, but not by dioctylglycerol pyrophosphate 8:0, an LPA(3) antagonist. Pertussis toxin, the inhibitors for PI3K and Akt also attenuated the inhibitory effect of LPA on CCL5/RANTES secretion. We also identify the transcription factor IFN regulatory factor-1 (IRF-1) as being essential for CCL5/RANTES production. Interestingly, LPA inhibited IFN-γ and TNF-α-induced IRF-1 activation by blocking the binding of IRF-1 to its DNA consensus sequence without changing IRF-1 induction and its nuclear translocation. Ki16425, pertussis toxin, and PI3K inhibitors attenuated the inhibitory effect of LPA on IRF-1 activation. Our results suggest that LPA inhibits IFN-γ- and TNF-α-induced CCL5/RANTES production in BEAS-2B cells by blocking the binding of IRF-1 to the CCL5/RANTES promoter. LPA(1) coupled to G(i) and activation of PI3K is required for this unique effect.
Matsuzaki
Shinichi
S
Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan.
Ishizuka
Tamotsu
T
Hisada
Takeshi
T
Aoki
Haruka
H
Komachi
Mayumi
M
Ichimonji
Isao
I
Utsugi
Mitsuyoshi
M
Ono
Akihiro
A
Koga
Yasuhiko
Y
Dobashi
Kunio
K
Kurose
Hitoshi
H
Tomura
Hideaki
H
Mori
Masatomo
M
Okajima
Fumikazu
F
D015153:Blotting, Western; D001980:Bronchi / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D018946:Chemokine CCL5 / Q000276:immunology / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000276:immunology / Q000378:metabolism*; D008246:Lysophospholipids / Q000276:immunology / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020545:Respiratory Mucosa / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D014158:Transcription, Genetic
D018946:Chemokine CCL5; D050856:Interferon Regulatory Factor-1; D008246:Lysophospholipids; C032881:lysophosphatidic acid