21255012

pubmed:Citation

4

Summary Histamine is a well-recognized modulator of vascular inflammation. We have shown that histamine, acting via H1 receptors (H1R), synergizes lipopolysaccharide (LPS)-induced production of prostaglandin I(2) (PGI(2)), PGE(2) and interleukin-6 (IL-6) by endothelial cells. The synergy between histamine and LPS was partly attributed to histamine -induced expression of Toll-like receptor 4 (TLR4). In this study, we examined whether LPS stimulates the H1R expression in human coronary artery endothelial cells (HCAEC) with resultant enhancement of histamine responsiveness. Incubation of HCAEC with LPS (10-1000 ng/ml) resulted in two-fold to fourfold increases in H1R mRNA expression in a time-dependent and concentration-dependent fashion. In contrast, LPS treatment did not affect H2R mRNA expression. The LPS-induced H1R mRNA expression peaked by 4 hr after LPS treatment and remained elevated above the basal level for 20-24 hr. Flow cytometric and Western blot analyses revealed increased expression of H1R protein in LPS-treated cells. The specific binding of [(3)H]pyrilamine to H1R in membrane proteins from LPS-treated HCAEC was threefold higher than the untreated cells. The LPS-induced H1R expression was mediated through TLR4 as gene silencing by TLR4-siRNA and treatment with a TLR4 antagonist inhibited the LPS effect. When HCAEC were pre-treated with LPS for 24 hr, washed and challenged with histamine, 17-, 10- and 15-fold increases in PGI(2), PGE(2) and IL-6 production, respectively, were noted. Histamine-induced enhancement of the synthesis of PGI(2), PGE(2) and IL-6 by LPS-primed HCAEC was completely blocked by an H1R antagonist. The results demonstrate that LPS, through TLR4 activation, up-regulates the expression and function of H1R and amplifies histamine-induced inflammatory responses in HCAEC.

eng

IM

MEDLINE

1365-2567

© 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd.

132

Y

pubmed-meshheading:21255012-Blotting, Western, pubmed-meshheading:21255012-Cells, Cultured, pubmed-meshheading:21255012-Coronary Vessels, pubmed-meshheading:21255012-Dinoprostone, pubmed-meshheading:21255012-Drug Synergism, pubmed-meshheading:21255012-Endothelial Cells, pubmed-meshheading:21255012-Epoprostenol, pubmed-meshheading:21255012-Flow Cytometry, pubmed-meshheading:21255012-Gene Expression, pubmed-meshheading:21255012-Histamine, pubmed-meshheading:21255012-Humans, pubmed-meshheading:21255012-Interleukin-6, pubmed-meshheading:21255012-Lipopolysaccharides, pubmed-meshheading:21255012-Pyrilamine, pubmed-meshheading:21255012-RNA, Messenger, pubmed-meshheading:21255012-RNA Interference, pubmed-meshheading:21255012-Radioligand Assay, pubmed-meshheading:21255012-Receptors, Histamine H1, pubmed-meshheading:21255012-Receptors, Histamine H2, pubmed-meshheading:21255012-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:21255012-Sulfonamides, pubmed-meshheading:21255012-Toll-Like Receptor 4, pubmed-meshheading:21255012-Tritium

Lipopolysaccharide induces H1 receptor expression and enhances histamine responsiveness in human coronary artery endothelial cells.

Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural