Interleukin-33 induces interleukin-8 expression via JNK/c-Jun/AP-1 pathway in human umbilical vein endothelial cells.

Katsuyuki Umebashi,Masayoshi Yamamoto,Michihisa Jougasaki,Akinori Tokito,Ramani Ramchandran

doi:10.1371/journal.pone.0191659

Katsuyuki Umebashi, Masayoshi Yamamoto + Show 3 more

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https://doi.org/10.1371/journal.pone.0191659

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Abstract

Interleukin (IL)-33 is a member of the IL-1 cytokine family with dual functions as a traditional cytokine and as a transcriptional regulator. We recently reported that IL-33 up-regulated growth regulated oncogene (GRO)-α/CXCL1 expression in human vascular endothelial cells. The aim of this study was to investigate the effect of IL-33 on the expression of IL-8/CXCL8, another member of the CXC-chemokine family, and to elucidate its signaling pathways in human umbilical vein endothelial cells (HUVECs). Immunocytochemical staining and Western immunoblot analysis revealed that IL-33 augmented IL-8 protein expression in HUVECs. Real time reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) showed that IL-33 significantly increased IL-8 mRNA and secretion in a dose- and time-dependent manner. IL-33 preferentially stimulated proliferating subconfluent cells, and increased IL-8 secretion to a higher level compared with confluent cells. IL-33 also stimulated phosphorylations of c-Jun N-terminal kinase (JNK) and c-Jun, and enhanced activator protein (AP)-1 DNA-binding activity, all of which were suppressed by SP600125, a JNK inhibitor. Moreover, IL-33-induced IL-8 mRNA and secretion were also suppressed by SP600125. Transfection of c-Jun small interfering RNA into cultured HUVECs significantly reduced the IL-33-induced increase in IL-8 secretion from HUVECs. The present study demonstrates that IL-33 induces IL-8 expression via JNK/c-Jun/AP-1 pathway in human vascular endothelial cells, and provides a new insight into the role of IL-33-induced IL-8 in the pathophysiology of atherosclerosis and vascular inflammation.

Highlights

We have demonstrated that IL-33 increases expression of growth regulated oncogene (GRO)-α, another member of the CXC-chemokine family, via activating mitogen activated protein kinase (MAPK) and nuclear factor (NF)-κB in human umbilical vein endothelial cells (HUVECs) [25]
The present study has demonstrated that IL-33, a member of the IL-1 cytokine family, induces the expression of IL-8, a member of the CXC-chemokine family in HUVECs
1) Immunocytochemical examination and Western immunoblot analysis demonstrated that IL-33 increased the IL-8 protein expression in HUVECs. 2) Real-time PCR and enzyme-linked immunosorbent assay (ELISA) showed that IL-33 increased IL-8 gene expression and protein secretion in a dose- and time-dependent manner in HUVECs, and the dose-dependent responses to IL-33 were weaker than those to IL-1β

Summary

Introduction

Atherosclerosis is considered a chronic inflammatory disease that causes acute cardiovascular events [1, 2], the regulation of inflammation in atherosclerosis is not fully clarified. Attachment of the leukocytes to the endothelial cells and subsequent migration of leukocytes into the subendothelial space are the initial events in atherosclerosis, and chemokines play an important role in its pathogenesis. Elevated levels of plasma IL-8 were associated with the increased risk of future coronary arterial diseases in healthy subjects [9]. These findings suggest that IL-8 plays an important role in the pathogenesis of atherosclerosis

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