Histamine H₄ receptor mediates eosinophil chemotaxis with cell shape change and adhesion molecule upregulation

Abstract

1 During mast cell degranulation, histamine is released in large quantities. Human eosinophils were found to express histamine H 4 but not H 3 receptors. The possible effects of histamine on eosinophils and the receptor mediating these effects were investigated in our studies. 2 Histamine (0.01-30 mM) induced a rapid and transient cell shape change in human eosinophils, but had no effects on neutrophils. The maximal shape change was at 0.3 mM histamine with EC 50 at 19 nM. After 60 min incubation with 1 mM histamine, eosinophils were desensitized and were refractory to shape change response upon histamine restimulation. Histamine (0.01-1 mM) also enhanced the eosinophil shape change induced by other chemokines. 3 Histamine-induced eosinophil shape change was mediated by the H 4 receptor. This effect was completely inhibited by H 4 receptor-specific antagonist JNJ 7777120 (IC 50 0.3 mM) and H 3 /H 4 receptor antagonist thioperamide (IC 50 1.4 mM), but not by selective H 1 , H 2 or H 3 receptor antagonists. H 4 receptor agonists imetit (EC 50 25 nM) and clobenpropit (EC 50 72 nM) could mimic histamine effect in inducing eosinophil shape change. 4 Histamine (0.01-100 mM) induced upregulation of adhesion molecules CD11b/CD18 (Mac-1) and CD54 (ICAM-1) on eosinophils. This effect was mediated by the H 4 receptor and could be blocked by H 4 receptor antagonists JNJ 7777120 and thioperamide. 5 Histamine (0.01-10 mM) induced eosinophil chemotaxis with an EC 50 of 83 nM. This effect was mediated by the H 4 receptor and could be blocked by H 4 receptor antagonists JNJ 7777120 (IC 50 86 nM) and thioperamide (IC 50 519 nM). Histamine (0.5 mM) also enhanced the eosinophil shape change induced by other chemokines. 6In conclusion, we have demonstrated a new mechanism of eosinophil recruitment driven by mast cells via the release of histamine. Using specific histamine receptor ligands, we have provided a definitive proof that the H 4 receptor mediates eosinophil chemotaxis, cell shape change and upregulation of adhesion molecules. The effect of H 4 receptor antagonists in blocking eosinophil infiltration could be valuable for the treatment of allergic diseases. The histamine-induced shape change and upregulation of adhesion molecules on eosinophils can serve as biomarkers for clinical studies of H 4 receptor antagonists.

Histamine‐induced actin polymerization in human eosinophils: An imaging approach for histamine H4 receptor

“…ORIGINAL ARTICLE chemoattractant gradients including that of histamine, and a crucial early step in the cell response to such mediators is polymerization of the actin cytoskeleton, which allows them to leave the bloodstream and enter the tissue where they cause inflammatory damage. It has been shown previously using flow cytometry that these histamine-induced cytoskeletal changes, pivotal for extravasation of the cells through the vessel walls and into the tissue, are mediated through H 4 R (11,12). This study demonstrates similar functionality using a different technology that has potentially enhanced screening utility, through the use of 96-well plates with an automated plate-stacker.…”

“…Herein, we show that an imaging approach for investigating H 4 R antagonists produces data of at least equivalent quality and robustness to that previously published using flow cytometry (11,12), namely that actin polymerization in histamine-stimulated human eosinophils occurs specifically through H 4 R, yet with the added advantage of a higher-throughput plate-based imaging methodology.…”

“…The H 4 R, the latest of the group to be identified (4)(5)(6)(7)(8)(9), has been found to be expressed on eosinophils (10,11) and to be involved directly in eosinophil chemotaxis (10), adhesion molecule upregulation (12), and cell shape change (11).…”

Histamine reverses IL-5-afforded human eosinophil survival by inducing apoptosis: Pharmacological evidence for a novel mechanism of action of histamine

“…[20][21][22] Furthermore, even higher concentrations of histamine have been reported to be necessary for the enhancement of apoptosis of neutrophils. [24] In addition, the histamine concentrations used in nasal [41,42] and inhalation [43] challenges are manifold as compared to the effective concentration used in this study.…”

“…[20] In addition, through the histamine H 4 receptor, histamine has also been found to mediate cell shape change, upregulation of adhesion molecules and to induce actin polymerisation and intracellular calcium mobilization in eosinophils. [21,22] Furthermore, histamine inhibits eosinophil degranulation via stimulation of the histamine H 2 receptors and a consequent elevation of intracellular levels of cAMP. [23] The effects of histamine on granulocyte apoptosis remain scantly studied.…”