Pigment epithelium-derived factor induces interleukin-10 expression in human macrophages by induction of PPAR gamma.
OBJECTIVE
In search for the anti-inflammation mechanism of PEDF, we investigate whether pigment epithelium-derived factor (PEDF) induces the gene expression of interleukin (IL)-10 in human macrophages and determine the molecular basis of this induction.


METHODS
Human macrophages derived from a monocytic cell line, THP-1, and peripheral monocytes were treated with PEDF. IL-10 expression was assessed by quantitative real-time PCR, enzyme-linked immunosorbent assay, semi-quantitative reverse transcriptase (RT)-PCR, and promoter-reporter assay. Activity of extracellular signal-regulated kinase 2 (ERK2) and p38 mitogen-activated protein kinase (MAPK) was assessed by immunoblotting using antibodies targeting phosphorylated kinases forms. Elk-1 and ATF-2 phosphorylation was determined as well. Pharmacological inhibitors were used to examine the involvement of ERK, p38 MAPK, and peroxisome proliferator-activated receptor gamma (PPARgamma) on the IL-10 expression induced by PEDF.


RESULTS
PEDF increased the levels of IL-10 mRNA and protein in THP-1 cells and human macrophages derived from peripheral monocytes. Blockade of activity of ERK or p38 MAPK attenuated PEDF effects on induction of PPARgamma and IL-10. PEDF increased the transcriptional activity of IL-10 promoter. The effect was synergistically augmented by PPARgamma agonist, but attenuated by inhibitors of PPARgamma, ERK or p38 MAPK. These results showed that PEDF promotes IL-10 expression at transcriptional level, and that this is achieved through the ERK2/p38MAPK-dependent PPARgamma expression.


CONCLUSIONS
The anti-inflammatory property of PEDF may in part through the induction of IL-10 in macrophages. Our study supports the therapeutic potential of PEDF and PPARgamma agonists in inflammatory diseases.
Yang
Su-Lin
SL
Centers for Disease Control, Taiwan.
Chen
Show-Li
SL
Wu
Ju-Yun
JY
Ho
Tsung-Chuan
TC
Tsao
Yeou-Ping
YP
D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D006801:Humans; D015151:Immunoblotting; D016753:Interleukin-10 / Q000235:genetics*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology*; D047495:PPAR gamma / Q000187:drug effects* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015843:Serpins / Q000494:pharmacology*; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
D005136:Eye Proteins; D016753:Interleukin-10; D019950:Mitogen-Activated Protein Kinase 1; D009414:Nerve Growth Factors; D047495:PPAR gamma; D012333:RNA, Messenger; D015843:Serpins; D048051:p38 Mitogen-Activated Protein Kinases; D000099174:Pigment Epithelium-Derived Factor