Anti-Allergic Drugs Tranilast and Ketotifen Dose-Dependently Exert Mast Cell-Stabilizing Properties

Abstract

Background: Anti-allergic drugs, such as tranilast and ketotifen, inhibit the release of chemokines from mast cells. However, we know little about their direct effects on the exocytotic process of mast cells. Since exocytosis in mast cells can be monitored electrophysiologically by changes in the whole-cell membrane capacitance (Cm), the absence of such changes by these drugs indicates their mast cell-stabilizing properties. Methods: Employing the standard patch-clamp whole-cell recording technique in rat peritoneal mast cells, we examined the effects of tranilast and ketotifen on the Cm during exocytosis. Using confocal imaging of a water-soluble fluorescent dye, lucifer yellow, we also examined their effects on the deformation of the plasma membrane. Results: Relatively lower concentrations of tranilast (100, 250 µM) and ketotifen (1, 10 µM) did not significantly affect the GTP-γ-S-induced increase in the Cm. However, higher concentrations of tranilast (500 µM, 1 mM) and ketotifen (50, 100 µM) almost totally suppressed the increase in the Cm, and washed out the trapping of the dye on the surface of the mast cells. Compared to tranilast, ketotifen required much lower doses to similarly inhibit the degranulation of mast cells or the increase in the Cm. Conclusions: This study provides electrophysiological evidence for the first time that tranilast and ketotifen dose-dependently inhibit the process of exocytosis, and that ketotifen is more potent than tranilast in stabilizing mast cells. The mast cell-stabilizing properties of these drugs may be attributed to their ability to counteract the plasma membrane deformation in degranulating mast cells.

Clarithromycin Dose-Dependently Stabilizes Rat Peritoneal Mast Cells

“…The protocol for animal use was approved by the Animal Care and Use Committee of the Tohoku University Graduate School of Medicine. Peritoneal mast cells were obtained by washing the peritoneal cavity with a standard external (bathing) solution containing: 145 m M NaCl, 4.0 m M KCl, 1.0 m M CaCl 2 , 2.0 m M MgCl 2 , 5.0 m M HEPES, and 0.01% bovine serum albumin (pH 7.2 adjusted with NaOH) as described in our previous studies [17,18,19]. They were maintained at room temperature (22-24°C) for use within 8 h. The mast cell suspension was scattered in a chamber placed on the head stage of an inverted microscope (Nikon, Tokyo, Japan).…”

“…They were maintained at room temperature (22-24°C) for use within 8 h. The mast cell suspension was scattered in a chamber placed on the head stage of an inverted microscope (Nikon, Tokyo, Japan). Single mast cells were easily distinguishable from other cells by their intracellular inclusion of secretory granules [17,18,19]. …”

“…Erythromycin and roxithromycin (Sigma-Aldrich Co., St. Louis, Mo., USA) and azithromycin (LKT Laboratories Inc., St. Paul, Minn., USA) were also dissolved in the external solution at a final concentration of 100 μ M . After incubation of mast cells in these solutions or a solution containing no drug for 10 min, exocytosis was externally induced by compound 48/80 (final concentration 10 μg/ml; Sigma-Aldrich) [17,18,19]. Bright-field images were acquired from randomly selected 0.1-mm 2 fields of view (10 views from 6 of each condition) as described in our previous studies [17,18,19].…”

“…However, due to the limitations of the methods used in molecular biology [16], the effects of these drugs on the exocytotic process could not directly been examined in mast cells. Recently, by monitoring the changes in whole-cell membrane capacitance (Cm) in mast cells, we provided for the first time electrophysiological evidence that antiallergic drugs, such as olopatadine, ketotifen, and tranilast, inhibit the process of exocytosis and thus have mast cell-stabilizing properties [17,18]. In the present study, employing this standard patch clamp whole-cell recording technique in rat peritoneal mast cells, we examined the effects of macrolide antibiotics, such as clarithromycin, erythromycin, roxithromycin, and azithromycin, on changes in Cm in order to determine the mechanism by which they stabilize mast cells.…”

Immunoinformatics Study of Procyanidins as Mast Cell Stabilizers

“…4,5 A novel strategy for antiallergic treatment can be postulated by designing molecules that can affect the receptor binding affinity of IgE. 6,7 Mast cell stabilizer block mast cell degranulation, stabilizing the cell and thereby preventing the release of histamine 8 and related mediators e.g. leukotrienes (for basophils) and prostaglandin D2 and IL-5 (for mast cells) during hypersensitivity reaction.…”