Interleukin-17 Stimulates STAT3-Mediated Endothelial Cell Activation for Neutrophil Recruitment.
OBJECTIVE
Interleukin-17 (IL-17) is a major pro-inflammatory cytokine that initiates and maintains inflammation. However, the molecular mechanisms as to how IL-17 influences endothelial cells to promote neutrophil recruitment are not fully understood.


METHODS
Human endothelial cells (HMECs) were stimulated with IL-17, and investigated for proliferation, migration, and tubule formation activities. Transwell chemotaxis and adhesion assays were performed to assess neutrophil recruitment. Cytokine production was measured by Cytokine Array Chip and ELISA. Western blotting and immunofluorescent analysis were used to detect the phosphorylation and translocation of STAT3. Specific inhibitors, small interfering RNA, and phosphorylation mutants were used to confirm that IL-17 induced STAT3 activation via IL-17RA signaling.


RESULTS
Activation of HMECs with IL-17 induced STAT3 phosphorylation and nuclear translocation, which were associated with induction of GRO-α, GM-CSF and IL-8, and neutrophil recruitment. Phosphorylation of STAT3 was identified mainly at the tyrosine in position 705 (Y705), and the Y705F mutants attenuated IL-17-mediated STAT3 activation. Moreover, specific inhibitors, FLLL31, or siRNA silencing of STAT3 attenuated HMECs activation, resulting in inhibition of GRO-α, GM-CSF, IL-8 production, and neutrophil recruitment. Furthermore, phosphorylation of STAT3 was identified as downstream of IL-17RA signaling.


CONCLUSIONS
IL-17 induced STAT3 activation as a necessary step in endothelial cell activation and neutrophil recruitment.
Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Shaopeng
S
Yuan
Shimeng
S
Zhang
Yuanyuan
Y
Zhuang
He
H
Zhang
Jinye
J
Bai
Qi
Q
Hou
D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D020381:Interleukin-17 / Q000378:metabolism* / Q000494:pharmacology; D055806:Microvessels / Q000166:cytology; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*
C508717:IL17A protein, human; D020381:Interleukin-17; D050796:STAT3 Transcription Factor; D019000:Phosphotyrosine