ER-27319, an acridone-related compound, inhibits release of antigen-induced allergic mediators from mast cells by selective inhibition of Fcɛ receptor I-mediated activation of Syk

ER-27319, an acridone-related compound, inhibits release of antigen-induced allergic mediators from mast cells by selective inhibition of Fcɛ receptor I-mediated activation of Syk

^*Department of Drug Discovery, Tsukuba Research Laboratories, Eisai Company, Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 30026, Japan; and ^†Section on Chemical Immunology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892

Communicated by Henry Metzger, National Institutes of Health, Bethesda, MD (received for review August 8, 1997)

Abstract

Engagement of the mast cell high-affinity receptor for immunoglobulin E (IgE), FcɛRI, induces tyrosine phosphorylation of Syk, a non-receptor tyrosine kinase, that has been demonstrated as critical for degranulation. Herein we describe a synthetic compound, ER-27319, as a potent and selective inhibitor of antigen or anti-IgE-mediated degranulation of rodent and human mast cells. ER-27319 affected neither Lyn kinase activity nor the antigen-induced phosphorylation of the FcɛRI but did effectively inhibit the tyrosine phosphorylation of Syk and thus its activity. As a consequence, tyrosine phosphorylation of phospholipase C-γ1, generation of inositol phosphates, release of arachidonic acid, and secretion of histamine and tumor necrosis factor α were also inhibited. ER-27319 did not inhibit the anti-CD3-induced tyrosine phosphorylation of phospholipase C-γ1 in Jurkat T cells, demonstrating a specificity for Syk-induced signals. In contrast the tyrosine phosphorylation and activation of Syk, induced by in vitro incubation with the phosphorylated immunoreceptor tyrosine-based activation motif (ITAM) of FcɛRI γ subunit or by antigen activation of RBL-2H3 cells, was specifically inhibited by ER-27319. However, when ER-27319 was added to immunoprecipitated Syk, derived from activated cells, no effect was seen on Syk activity. ER-27319 did not inhibit the tyrosine phosphorylation of Syk induced by activation in the presence of Igβ ITAM or the anti-IgM-induced phosphorylation of Syk in human peripheral B cells. Therefore, ER-27319 selectively interferes with the FcɛRI γ phospho-ITAM activation of Syk in vitro and in intact cells. These results confirm the importance of Syk in FcɛRI-mediated responses in mast cells and demonstrate the mast cell selectivity and therapeutic potential of ER-27319 in the treatment of allergic disease.

Footnotes

↵ ‡ To whom reprint requests should be addressed. e-mail: k1-yamada{at}eisai.co.jp.
ABBREVIATIONS:

ER-27319,

3,4-dimethyl-10-(3-aminopropyl)-9-acridone oxalate;

FcɛRI,

the high-affinity receptor for IgE;

SH2,

src homology domain 2, ITAM, immunoreceptor tyrosine-based activation motif;

PLC-γ1,

phospholipase C-γ1;

PKC,

protein kinase C;

TNFα,

tumor necrosis factor α;

GST,

glutathione S-transferase;

DNP,

o-dinitrophenyl;

pLTs,

peptide leukotrienes