Inhibition by azelastine of nonallergic histamine release from rat peritoneal mast cells

The ability of azelastine and selected antiallergic drugs to inhibit compound 48/80-induced and PS-potentiated, Con A-induced histamine release from RPMC was investigated. Azelastine, ketotifen, theophylline, and DSCG added simultaneously with the secretagogues or preincubated with the RPMC for 10 min before the addition of secretagogues produced concentration-dependent inhibition of histamine release. In general, the relative order of potency at calculated IC50 level was as follows: azelastine greater than ketotifen greater than theophylline greater than DSCG. The preincubation of RPMC with azelastine for 10 min exerted 3.5 times greater inhibition of Con A plus PS-stimulated histamine release but did not influence the inhibitory activity on compound 48/80-induced release. The duration of preincubation did not influence the inhibitory effects of ketotifen with either secretagogue. Theophylline and DSCG exerted significantly greater inhibition when they were added simultaneously with Con A plus PS. The inhibitory activity of DSCG was also significantly improved upon simultaneous addition with compound 48/80. These data demonstrated that azelastine is the most potent inhibitor of nonallergic histamine release from RPMC among the four antiallergic drugs examined.     

Effects of oestrogenic agents on rat peritoneal mast cells

Objectives and design:  The objective of this study was to explore whether increased levels of inflammatory cytokines are associated with the risk of clinically silent coronary artery disease. Subjects:  Three-hundred-fifty-six black adults aged 25–54 residing in inner city of Baltimore, Maryland, United States were included in this study. Methods:  Sociodemographics were assessed as were lipid profiles, IL-6, tumor necrosis factor-alpha (TNF-alpha), soluble intercellular adhesion molecule-1 (sICAM-1), and high-sensitivity C-reactive protein (hs-CRP) levels. Computed tomography (CT) coronary angiography was performed. Results:  Coronary calcification was identified in 22.5 % participants and 14 % had significant (≥50 %) coronary stenosis. Multiple logistic regression analyses suggested that IL-6 levels were independently associated with the presence of coronary calcification and significant coronary stenosis, while TNF-alpha, sICAM-1 and hs-CRP levels were not. Conclusions:  This study underscores a critical role for IL-6 in atherosclerosis and suggests that IL-6 may be a marker for significant coronary stenosis in cardiovascularly asymptomatic individuals. This research was funded by National Institute on Drug Abuse grants RO1-DA12777 (Lai S), and RO1-DA15020 (Lai S). Received 22 November 2007; returned for revision 28 May 2008; received from final revision 6 August 2008; accepted by M. Parnham 7 August 2008     

Effects of histamine agonists and antagonists on rat peritoneal mast cells

Inflammation Research -     

Inhibition of IgE-mediated allergic histamine release from rat peritoneal mast cells by azelastine and selected antiallergic drugs

The ability of azelastine to inhibit IgE-mediated allergic histamine release from the peritoneal mast cells of actively sensitized rats was investigated and compared with selected antiallergic agents. Azelastine added simultaneously with the allergic stimuli (ovalbumin, OA, 10 g/ml + phosphatidylserine, PS, 10 g/ml) or preincubated with cells for 10 min prior to antigen challenge produced similar concentration-dependent inhibition of allergic histamine release. The IC_50s (M) following 10-min preincubation were as follows: azelastine = 4.8; astemizole = 86.3; ketotifen = 112.2; diphenhydramine = 133 and theophylline = 2040.3. At IC₅₀ level azelastine was about 18, 23, 28 and 425 times as effective as astemizole, ketotifen (newer histamine H₁-receptor antagonists), diphenhydramine (a traditional H₁-receptor antagonist), and theophylline (a phosphodiesterase inhibitor), respectively. Sodium cromoglycate in a concentration range or 1–1000 M (0 or 10-min preincubation) failed to exert any inhibitory effect. These data showed that among six drugs tested azelastine is the most potent inhibitor of allergic histamine release from rat peritoneal mast cells.     

Effects of prostanoid receptor agonists on immunologically-activated rat peritoneal mast cells

Inflammation Research -     

Effects of taurine, carnosine, and casomorphine on functional activity of rat peritoneal mast cells

We studied the effects of taurine, carnosine, and casomorphine on histamine release from rat peritoneal mast cells induced by compound 48/80 and ionophore A23187. Differences were revealed in the effect of the test preparations. Taurine inhibited histamine release induced by ionophore A23187, but not by compound 48/80. Carnosine abolished the stimulatory effect of compound 48/80 on histamine release, but did not modulate the effect of ionophore A23187. Casomorphine inhibited histamine release induced by ionophore A23187, but potentiated the effect of compound 48/80. The mechanisms for these effects are discussed. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 3, pp. 302–305, March, 2006     

Inhibition of allergic histamine release from rat peritoneal mast cells by azelastine. Interaction with selected antiasthmatic drugs

The in vitro interaction of azelastine (a new antiallergic/antiasthmatic drug) with albuterol (a beta 2 bronchodilator), theophylline (a phosphodiesterase inhibitor), disodium cromoglycate (DSCG, a mast cell-stabilizing agent) and prednisolone (a steroid) was studied for effects on allergic histamine release from rat peritoneal mast cells (RPMCs). The RPMCs preincubated with albuterol, theophylline, DSGC (10 min) and prednisolone (2h) caused a 2- to 18-fold decrease in the IC30 for azelastine. Significant potentiation (synergism) was seen only with albuterol (0.01, 0.1 and 1.0 microM, 10 min) and theophylline (1.0 microM, 10 min). The pre-exposure of RPMCs with DSCG (0.1, 1.0 and 10 microM) for a period of 10 min produced a slight leftward shift of azelastine's concentration-effect curve (0.01, 0.1 and 10 microM added immediately before antigen challenge). This effect was not dependent on the concentration of DSCG. These data demonstrated (1) the lack of cross-tachyphylaxis between DSCG and azelastine, and (2) the synergistic interaction between azelastine and albuterol or theophylline.     

Microfilament-associated, local degranulation of rat peritoneal mast cells

When compound 48/80 was applied by means of microelectrophoresis to the surface of a rat peritoneal mast cell, localized degranulation was observed in the area close to the microelectrode tip. The extruded granules were connected to the cell surface by filaments. The filaments were elongated radially and, in some occasions, projected to a length of 5 microns. A few minutes later, the length of the protruded filaments became shorter and shorter and, finally, the extruded granules were reincorporated into the cell. When rhodamine-phalloidin, an F-actin-specific dye, was perfused the extruded granules and filaments were stained by this dye. This indicates that actin filaments or fragments of them exist on the granule surface and on the cell surface at the site of degranulation. These actin filaments bound to the mast cell granules may play an important role, not only for the extrusion of the granules, but also for the reuptake of extruded granules into the cytoplasm.     

Effects of antihistamines on isolated rat peritoneal mast cells and on model membrane systems

We have examined the effect of a range of histamine H₁- and H₂-receptor agonists and antagonists on rat peritoneal mast cells. Most of the compounds had a dual action: at low concentrations they inhibited the histamine release produced by immunologic activation of the cell whereas, at higher concentrations they themselves induced a cytotoxic release of the amine. The test agents did not affect intracellular levels of cyclic AMP. In model systems the majority of the drugs had no effect, on the intergrity of artificial liposomes but did protect rat erythrocytes against osmotic shock. We then propose that these agents produce their effects on mast cells by a direct action on the cell membrane, with low concentrations becoming incorporated into the bilayer in such a way as to stabilize the structure and high concentrations disrupting the membrane and leading to cell lysis.     

Factor-independent tissue cultured mast cells: establishment from rat peritoneal mast cells

We report here that extended culture of purified rat peritoneal mast cells (RpMC), typical of the connective tissue-type (CTMC), gives rise to continuously proliferative cell lines without the requirement of exogenous growth factors such as IL-3 and IL-4 or accessory cells. Two of the cell lines established, RCMC1 and RCMC2, are described here. Both cell lines have been maintained in continuous culture in vitro for over a year. Although these cell lines were derived from CTMC, they exhibit phenotypic characteristics of mucosal-type mast cells, i.e., they contain rat mast cell protease II (RMCP II), low levels of histamine and stain alcian blue+/safranin-. Previous studies have identified both high and low affinity receptors for IgE, designated Fc epsilon RI and Rc epsilon RII, respectively, on RpMC and rat basophilic leukemia (RBL) cells. At the early stages of cell culture, RCMC1 expressed predominantly Fc epsilon RI and a gradual increase in the expression of Fc epsilon RII has been observed with time in culture. By comparison, RCMC2 expressed predominantly Fc epsilon RII throughout its entire period of cell culture.     

Effects of genistein on rat ileum smooth muscle contraction and histamine release from rat peritoneal mast cells

Inflammation Research - .     

Effects of type I and type II phospholipase A2 on rat peritoneal mast cells

Inflammation Research -     

Mechanism of histamine release from rat peritoneal mast cells

Summary The present communication endeavours to elucidate the mechanism of histamine release from rat peritoneal mast cells induced by selective histamine liberators.Of the different enzymatic processes involved in secretion the following are considered: ecto-ATPase activity in the mast cell, pro-esterase-esterase conversion during histamine secretion, cyclic AMP and microtubule association/dissociation, phospholipase A₂ and the effect of phospholipid metabolites on secretion, N-methyl transferase and the methylation of phospholipids and the phosphorylation and desphosphorylation of proteins.     

Desensitization of rat peritoneal mast cells to substance P

Rat peritoneal mast cells were pretreated for 10 min at 37°C with either substance P (SP, 3 or 6 M) or compound 48/80 (37.5, 50 or 75 ng/ml). The effect of this pretreatment on the subsequent responsiveness of the cells to SP was studied. Both SP and compound 48/80 pretreatment of rat peritoneal mast cells inhibited the subsequent response of the cells to SP. The degree of inhibition produced by either SP or compound 48/80 was dependent on the concentration used to pretreat the cells. Inhibition of the response of the cells to SP was observed whether or not the pretreating agent was removed or remained in contact with the cells during the subsequent stimulation with SP. It is concluded that compound 48/80 and SP desensitize the cells to subsequent stimulation by SP and possible mechanisms for this are discussed.     

Effect of loop diuretics on rat peritoneal and human lung mast cells

The effects of furosemide and bumetanide on immunologically stimulated rat peritoneal and human lung mast cells were compared. Furosemide and bumetanide had different modulatory actions on the rat peritoneal mast cell. Furosemide inhibited anti-IgE-induced histamine release. Preincubation of the cells with the drug, prior to anti-IgE stimulation, significantly reduced furosemide's inhibitory effect. In contrast, bumetanide potentiated anti-IgE-induced histamine secretion from the rat peritoneal mast cell. Both diuretics were modest inhibitors of anti-IgE-mediated histamine release from human lung mast cells. For furosemide, inhibition decreased with preincubation, while preincubation increased bumetanide's inhibitory action.     

Effect of dantrolene on histamine release from rat peritoneal mast cells

Dantrolene strongly and dose-dependently inhibited histamine release from rat peritoneal mast cells induced by anti-IgE. Dantrolene inhibited Ca²⁺-mobilization from intracellular Ca²⁺-store as well as histamine release in mast cells activated by anti-IgE, the effect on both of these phenomena being closely correlated. These results suggested that the effect of dantrolene on histamine release from rat mast cell might be due to the inhibition of Ca²⁺-release from intracellular Ca²⁺-store.     

Calcium efflux and histamine secretion from rat peritoneal mast cells

Purified rat peritoneal mast cells rapidly accumulated⁴⁵calcium from the external medium. The uptake was essentially unaffected by lanthanide ions but was almost totally prevented by metabolic inhibitors. Cells preloaded with⁴⁵calcium showed a steady efflux of the cation on transfer to a medium lacking the isotope. The efflux was unaffected by metabolic inhibitors but was totally dependent on extracellular sodium ions. These results indicate the operation of a sodium-calcium exchange mechanism for the extrusion of the divalent cation. Antigenic or pharmacologic stimulation of the mast cell led to a temporary suppression of calcium efflux during the period in which histamine release occurred. This effect was potentiated by phosphatidylserine and high concentrations of the lipid inhibited basal efflux. These results suggest that activation of the mast cell leads to an inhibition of calcium extrusion, thereby potentiating the induced rise in the intracellular concentration of the cation and thus augmenting the secretory response.