Email updates

Keep up to date with the latest news and content from JNI and BioMed Central.

Open Access Highly Accessed Research

(−)-Epigallocatechin gallate inhibits endotoxin-induced expression of inflammatory cytokines in human cerebral microvascular endothelial cells

Jieliang Li12, Li Ye2, Xu Wang2, Jinping Liu2, Yizhong Wang2, Yu Zhou2 and Wenzhe Ho12*

Author Affiliations

1 The Center for Animal Experiment/Animal Biosafety Level III Laboratory, Wuhan University Wuhan, Hubei, 430071, People's Republic of China

2 Department of Pathology and Laboratory Medicine, Temple University School of Medicine, 843 MERB, 3500N Broad Street, Philadelphia, PA, 19140, USA

For all author emails, please log on.

Journal of Neuroinflammation 2012, 9:161  doi:10.1186/1742-2094-9-161

Published: 6 July 2012

Abstract

Background

(−)-Epigallocatechin gallate (EGCG) is a major polyphenol component of green tea that has antioxidant activities. Lipopolysaccharide (LPS) induces inflammatory cytokine production and impairs blood–brain barrier (BBB) integrity. We examined the effect of EGCG on LPS-induced expression of the inflammatory cytokines in human cerebral microvascular endothelial cells (hCMECs) and BBB permeability.

Methods

The expression of TNF-α, IL-1β and monocyte chemotactic protein-1 (MCP-1/CCL2) was determined by quantitative real time PCR (qRT-PCR) and ELISA. Intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule (VCAM) in hCMECs were examined by qRT-PCR and Western blotting. Monocytes that adhered to LPS-stimulated endothelial cells were measured by monocyte adhesion assay. Tight junctional factors were detected by qRT-PCR (Claudin 5 and Occludin) and immunofluorescence staining (Claudin 5 and ZO-1). The permeability of the hCMEC monolayer was determined by fluorescence spectrophotometry of transmembrane fluorescin and transendothelial electrical resistance (TEER). NF-kB activation was measured by luciferase assay.

Results

EGCG significantly suppressed the LPS-induced expression of IL-1β and TNF-α in hCMECs. EGCG also inhibited the expression of MCP-1/CCL2, VCAM-1 and ICAM-1. Functional analysis showed that EGCG induced the expression of tight junction proteins (Occludin and Claudin-5) in hCMECs. Investigation of the mechanism showed that EGCG had the ability to inhibit LPS-mediated NF-κB activation. In addition, 67-kD laminin receptor was involved in the anti-inflammatory effect of EGCG.

Conclusions

Our results demonstrated that LPS induced inflammatory cytokine production in hCMECs, which could be attenuated by EGCG. These data indicate that EGCG has a therapeutic potential for endotoxin-mediated endothelial inflammation.

Keywords:
67LR; endothelial; (−)-epigallocatechin gallate; LPS; NF-κB