Lipoxin A4 negatively regulates lipopolysaccharide-induced differentiation of RAW264.7 murine macrophages into dendritic-like cells.
BACKGROUND
Lipoxins (LXs), endogenous anti-inflammatory and pro-resolving eicosanoids generated during various inflammatory conditions, have novel immunomodulatory properties. Because dendritic cells (DCs) play crucial roles in the initiation and maintenance of immune response, we determined whether LXs could modulate the maturation process of DCs and investigated the effects of lipoxin A(4) (LXA(4)) on lipopolysaccharide (LPS)-induced differentiation of RAW264.7 cells into dendritic-like cells.


METHODS
RAW264.7 cells were cultured in vitro with 1 microg/ml LPS in the absence or presence of LXA(4) for 24 hours, and cellular surface markers (MHC-II, CD80 (B7-1), CD86 (B7-2)) were measured by flow cytometry (FCM). Mixed lymphocyte reaction was performed to evaluate the allostimulatory activity. Cytoplastic IkappaB degradation and nuclear factor kappa B (NF-kappaB) translocation were detected by Western blotting. Luciferase reporter plasmid was transiently transfected into RAW264.7 cells, and luciferase activity was determined to measure the transcriptional activity of NF-kappaB.


RESULTS
LXA(4) reduced the ratio of LPS-treated RAW264.7 cells to DCs with morphological characteristics and inhibited the expression of MHC II. LPS-induced up-regulation of CD86 was moderately suppressed by LXA(4) but no obvious change of CD80 was observed. Moreover, LXA(4) weakened the allostimulatory activity of LPS-treated RAW264.7 cells. These alterations of LPS+LXA(4)-treated cells were associated with a marked inhibition of IkappaB degradation, NF-kappaB translocation and then the transcriptional activity of NF-kappaB.


CONCLUSIONS
LXA(4) negatively regulates LPS-induced differentiation of RAW264.7 cells into dendritic-like cells. This activity reveals an undescribed mechanism of LXA(4) to prevent excessive and sustained immune reaction by regulating maturation of DCs.
Zhang
Li
L
Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Wu
Ping
P
Jin
Sheng-wei
SW
Yuan
Ping
P
Wan
Jing-yuan
JY
Zhou
Xiao-yan
XY
Xiong
Wei
W
Fang
Feng
F
Ye
Du-yun
DY
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology*; D051550:I-kappa B Kinase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D044045:Lipoxins / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D010641:Phenotype; D014158:Transcription, Genetic / Q000187:drug effects
D008070:Lipopolysaccharides; D044045:Lipoxins; D016328:NF-kappa B; C040527:lipoxin A4; D051550:I-kappa B Kinase