Laminar flow attenuates interferon-induced inflammatory responses in endothelial cells.
OBJECTIVE
Atherosclerosis is a chronic disease that involves inflammation, in which cytokines, including interferon-gamma (IFNgamma), participate. Endothelial cells (ECs) exposed to IFNgamma increase the expression of CXC chemokines. ECs subjected to laminar flow (LF) are atheroprotective, despite an unclear mechanism. This study was conducted to analyze whether ECs under LF were protected from IFNgamma-induced responses.


METHODS
IFNgamma-treated human umbilical cord ECs were subjected to LF in a well-defined flow chamber system. IFNgamma-induced STAT1 activation and downstream target genes were examined.


RESULTS
ECs exposed to IFNgamma triggered STAT1 activation via the phosphorylation of Tyr701 and Ser727 in STAT1. ECs exposed to LF alone did not activate STAT1. LF exposure of IFNgamma-treated ECs significantly attenuated IFNgamma-induced Tyr701 phosphorylation in a shear-force- and time-dependent manner, whereas Ser727 phosphorylation was unaffected. Consistently, LF inhibited IFNgamma-induced STAT1 binding to DNA. ECs treated with IFNgamma induced the expression of three T-cell-specific CXC chemokines (CXCL9, CXCL10 and CXCL11) as well as CIITA, a transcriptional regulator of major histocompatibility complex class II (MHCII). Consistently, LF exposure of IFNgamma-treated ECs reduced the expression of CXC chemokines and CIITA.


CONCLUSIONS
LF attenuates IFNgamma-induced responses via the suppression of STAT1 activation. Inhibition by LF of the interferon-induced ECs' response may explain some aspects of LF's atheroprotective effects on the endothelium.
Tsai
Yu-Chih
YC
Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
Hsieh
Hsyue-Jen
HJ
Liao
Fang
F
Ni
Chih-Wen
CW
Chao
Yuen-Jen
YJ
Hsieh
Chung-Yu
CY
Wang
Danny Ling
DL
D050197:Atherosclerosis / Q000276:immunology*; D015153:Blotting, Western; D002465:Cell Movement; D002478:Cells, Cultured; D054357:Chemokine CXCL10; D054371:Chemokine CXCL11; D054370:Chemokine CXCL9; D019743:Chemokines, CXC / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D034622:RNA Interference; D011994:Recombinant Proteins; D012039:Regional Blood Flow; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000378:metabolism; D013314:Stress, Mechanical; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism
C515202:CXCL11 protein, human; C080810:CXCL9 protein, human; D054357:Chemokine CXCL10; D054371:Chemokine CXCL11; D054370:Chemokine CXCL9; D019743:Chemokines, CXC; C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D007371:Interferon-gamma