Interleukin-13 upregulates eotaxin expression in airway epithelial cells by a STAT6-dependent mechanism.
Interleukin (IL)-13 is a T helper 2-derived cytokine that has recently been implicated in allergic airway responses. We hypothesized that IL-13 may regulate expression of eotaxin in airway epithelium. We found that IL-13 upregulated eotaxin messenger RNA and protein synthesis in the airway epithelial cell line BEAS-2B; this effect showed synergy with tumor necrosis factor (TNF)-alpha and also was inhibited by the glucocorticoid budesonide. To establish the mechanisms of eotaxin upregulation by IL-13, cells were transfected with an eotaxin promoter-luciferase reporter plasmid and transcription was activated by IL-13 (1.7-fold) and TNF-alpha (2.8-fold). The combination of IL-13 and TNF-alpha additively activated the promoter constructs (4.1-fold). Activation of signal transducer and activator of transcription (STAT) 6 by IL-13 was confirmed by nuclear protein binding to a DNA probe derived from the eotaxin promoter. Activation of eotaxin transcription by IL-13 and the additive effect with TNF-alpha were lost in plasmids mutated at a putative STAT6 binding site. Cotransfection with a wild-type STAT6 expression vector significantly enhanced activation of the eotaxin promoter after IL-13 stimulation (6-fold induction). A significant increase of eotaxin protein secretion in the supernatant of STAT6 wild-type-transfected cells was observed after IL-13 stimulation. Cotransfection with a dominant negative STAT6 mutant expression vector inhibited activation of the eotaxin promoter by IL-13. These results indicate that IL-13 stimulates eotaxin expression in airway epithelial cells and that STAT6 plays a pivotal role in this response.
Matsukura
S
S
Johns Hopkins Asthma and Allergy Center, Baltimore, Maryland, USA.
Stellato
C
C
Georas
S N
SN
Casolaro
V
V
Plitt
J R
JR
Miura
K
K
Kurosawa
S
S
Schindler
U
U
Schleimer
R P
RP
D002461:Cell Line, Transformed; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D050800:STAT6 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation
C515456:CCL11 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines; D018793:Interleukin-13; D012333:RNA, Messenger; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators