Stimulus-secretion coupling in rat mast cells: inactivation of extracellular calcium dependent secretion

Investigation into the mast cell stabilizing activity of nature-identical and synthetic indanones

As part of an ongoing search for novel molecules with therapeutic potential we examined the mediator release inhibition activity of a number of indanones and their derivatives. The aldol condensation product 18 was approximately twice as potent as disodium cromoglycate as an inhibitor of compound 48/80-stimulated histamine release from rat peritoneal mast cells. The activity of this class of dimeric indanone compound is significantly higher than controls and may represent a new class of mast cell stabilizing agents. Compound 18 has been selected for further biological evaluation of its mast cell stabilization profile.

Three distinct anti-allergic drugs, amlexanox, cromolyn and tranilast, bind to S100A12 and S100A13 of the S100 protein family

To investigate the roles of calcium-binding proteins in degranulation, we used three anti-allergic drugs, amlexanox, cromolyn and tranilast, which inhibit IgE-mediated degranulation of mast cells, as molecular probes in affinity chromatography. All of these drugs, which have different structures but similar function, scarcely bound to calmodulin in bovine lung extract, but bound to the same kinds of calcium-binding proteins, such as the 10-kDa proteins isolated in this study, calcyphosine and annexins I-V. The 10-kDa proteins obtained on three drug-coupled resins and on phenyl-Sepharose were analysed by reversed-phase HPLC. It was found that two characteristic 10-kDa proteins, one polar and one less polar, were bound with all three drugs, although S100A2 (S100L), of the S100 family, was bound with phenyl-Sepharose. The cDNA and deduced amino acid sequence proved our major polar protein to be identical with the calcium-binding protein in bovine amniotic fluid (CAAF1, S100A12). The cDNA and deduced amino acid sequence of the less-polar protein shared 95% homology with human and mouse S100A13. In addition, it was demonstrated that the native S100A12 and recombinant S100A12 and S100A13 bind to immobilized amlexanox. On the basis of these findings, we speculate that the three anti-allergic drugs might inhibit degranulation by binding with S100A12 and S100A13.

Two distinct anti-allergic drugs, amlexanox and cromolyn, bind to the same kinds of calcium binding proteins, except calmodulin, in bovine lung extract

In order to explore candidates for proteins required in exocytosis, we used two anti-allergic drugs, amlexanox and cromolyn, which inhibit IgE mediated degranulation of mast cells and basophils, as molecular probes in affinity chromatography. These two drugs chiefly bound to the same kinds of calcium binding proteins in bovine lung. These proteins were as follows: bovine calgranulin C homolog, an 8-kDa unknown protein, S-100L, calgranulin B, calcyphosine, and annexins I-V. The homologous affinity of the two drugs to these proteins is in accord with the similar anti-allergic property of both drugs. From these findings it is presumed that these drugs interact with these proteins and affect pharmacologically the degranulation.

Inhibitory effects of the neurotensin8-13 analogs Asp13-NT8-13 and Asp12-NT8-13 on mast cell secretion

Pretreatment of isolated mast cells with analogs of neurotensin 8-13 (NT8-13), in which the amino acids Leu13 or Ile12 are replaced with an aspartic acid (Asp13-NT8-13 or Asp12-NT8-13), inhibits the secretion of histamine in response to NT. A 10 min pretreatment with either analog (10 microM) inhibited NT-induced histamine release by 90% (Asp13-NT8-13) or by 98% (Asp12-NT8-13). At concentrations that are inhibitory, Asp13-NT8-13 and Asp12-NT8-13 alone elicit very little release (< 5% at 10 microM). In the continued presence of the analogs, the inhibitory effect lasts for more than 45 min; removal of the analogs resulted in restoration of sensitivity to NT within 10 min. Pretreatment with analog Asp13-NT8-13 resulted in a 39% inhibition of stimulation by substance P and a 52% inhibition of stimulation by histamine-releasing peptide (HRP). In contrast, pretreatment with analog Asp12-NT8-13 gave no inhibition of release by SP or HRP. Neither analog inhibited histamine release in response to bradykinin (BK), NT1-12, compound 48/80 (48/80), the calcium ionophore A23187, or anti-IgE stimulation of passively sensitized mast cells. Although Asp12-NT8-13 and Asp13-NT8-13 differ slightly in regard to the peptides they inhibit, both probably act at a step early in the stimulus-secretion coupling sequence; most likely before the rise in the level of free intracellular calcium that has been shown to accompany secretion in mast cells. It is suggested that these analogs exert their inhibitory effect on NT by competing with NT for a binding site on the mast cell membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Generation of histamine-releasing activity from serum albumin by medium derived from stimulated neutrophils of rat

1. Medium conditioned by rat neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (FMLP) has been found to generate mast cell histamine-releasing activity (HRA) when incubated with bovine serum albumin (BSA). 2. Histamine release increased as the concentration of BSA used to generate HRA was increased from 0.25 to 10 mg ml-1, as the concentration of neurotrophil conditioned medium was increased and as the concentration of FMLP used to stimulate the neutrophils was increased. Histamine release was non-cytotoxic as it was inhibited by energy deprivation or by removal of calcium and it was accompanied by degranulation. 3. HRA was detectable after 30 min of incubation with BSA and its generation continued to increase over the 18 h of our measurements. 4. Generation of HRA was dependent upon the presence of medium from stimulated neutrophils and on the presence of BSA, although plasma could substitute for BSA. Likewise, HRA could be generated from gamma-globulin although to a lesser extent than with albumin. 5. Generation was optimum at acid pH and was inhibited by prior boiling of the neutrophil conditioned medium or by the addition of pepstatin. 6. It is suggested that an enzyme(s) released from the neutrophil during stimulation acts on an albumin-like substrate to generate HRA. It is proposed that HRA is peptide in nature and may be generated during an inflammatory response.

A patch-clamp study: secretagogue-induced currents in rat peritoneal mast cells

Ca2+ entry through plasma membrane has been considered to play a significant role in elevating cytosolic free Ca2+ concentrations during stimulus-secretion coupling in mast cells, but electrophysiological evidence of the Ca2+ channels is lacking. We examined the properties of secretagogue (compound 48/80)-induced currents in rat peritoneal mast cells, using the patch-clamp technique. In the whole cell recordings, the addition of compound 48/80 induced transient currents that were suppressed by Cd or reduced by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). In Ringer solution containing 2 mM Ca2+, the current-voltage relation was fairly linear from -100 to 50 mV and the reversal potential was 14 +/- 10.1 mV (n = 9). When the external Ca2+ was approximately 1 microM, the compound 48/80-induced currents were marginal, but readmission of Ca2+ or Ba2+ to the bath solution led to an appearance of the currents. In the cell-attached patches, the stimulation enhanced the activity of inward current mediated by Ba2+. The unitary inward Ba2+ current was characterized by the unitary conductance of 10.5 +/- 2.0 pS (n = 10) with isotonic BaCl2 pipette solution, the extrapolated reversal potential of 60.7 +/- 16.0 mV (n = 10) positive to the resting membrane potentials. The percent open time of the inward Ba2+ current channel was not appreciably changed by voltage. In some whole cell recordings, an increase in openings of the cation-selective channel (20-45 pS) was identified in the stimulated cells. When the external Na+ was completely replaced by choline+, the compound 48/80-induced currents had a fairly linear current-voltage relation.(ABSTRACT TRUNCATED AT 250 WORDS)

Replenishment of the cellular calcium required for non-immunologic stimulation of mast cell histamine secretion: temperature sensitivity and inhibition by manganese and sodium-free conditions

Mast cells depleted of cellular calcium (Ca) by a 3 hr exposure to Ca-free conditions and then bathed in Ca-free Locke failed to release histamine when stimulated by compound 48/80 or peptides. The cellular Ca required for histamine release could be replenished by a 5 sec exposure to extracellular Ca at 37 degrees C. To inhibit this replenished cellular Ca dependent histamine secretion required an additional 3 hr exposure to Ca-free conditions. When cellular Ca was replenished at 4 degrees C, an additional 2 min incubation at 37 degrees C was required to restore stimulated secretion to a maximum. During this 2 min incubation period the replenished cellular Ca is suggested to be "processed" so that it can be used for secretion. Manganese (Mn) or cobalt added during (but not after) this 2 min incubation period prevented the restoration of histamine release. Preincubation of cellular Ca depleted mast cells in Mn (0.1-1 mM) blocked the effect of subsequent Ca replenishment at 37 degrees C while cobalt and barium were less inhibitory. Neither magnesium nor strontium were inhibitory. Extracellular sodium (Na) was required for the restoration of cellular Ca dependent histamine secretion. Lithium could substitute for Na but rubidium and potassium were ineffective.

Viability and recovery from degranulation of isolated rat peritoneal mast cells

Using a culture system that allows prolonged maintenance of purified populations of peritoneal mast cells, we have examined them following stimulation by non-immunologic or immunologic agents. Employing phase-contrast microscopy of living cells and various pharmacological manipulations, we have noted that the recovery process includes a reduction in cell size, the probable sealing of exocytotic cavities, a pronounced displacement of the cell nucleus and a resynthesis of histamine. During recovery, mast cells can entrap molecules from the extracellular fluid and later release these substances by a Ca-dependent mechanism. Our results suggest that microfilaments, calmodulin, Ca, and metabolic energy are necessary for recovery.

Loss of quin 2 accompanies degranulation of mast cells

Stimulation of quin 2 loaded mast cells in the presence of 1 mM extracellular calcium produced a rapid and sustained increase in quin 2 fluorescence. This was accompanied by degranulation and the release of histamine. When Ca was replaced by EGTA or when Mn was present, a decrease in fluorescence accompanied degranulation. The increase in quin 2 fluorescence accompanying stimulation of mast cells appears to be due to the interaction of extracellular Ca with quin 2 associated with the secretory granule matrix released upon exocytosis.

Mast cell secretion: differences between immunologic and non-immunologic stimulation

Non-immunologic and immunologic stimulation of mast cells have been compared. Non-immunologic stimulation relys heavily on cellular Ca, is unaffected by neuraminidase treatment, shows a rapid inactivation, and elicits no increase in the incorporation of 3H-methyl groups into the lipid fraction. In contrast, stimulation by immunologic agents relys primarily on extracellular Ca, is inhibited by neuraminidase treatment, shows a comparatively slow rate of inactivation, and causes a significant increase in the incorporation of 3H-methyl groups into the lipid fraction. We found no evidence of cross-inactivation or desensitization between immunologic and non-immunologic agents. However, pretreatment of mast cells with neurotensin desensitized them to subsequent stimulation by compound 48/80. Our results support the hypothesis that immunologic and non-immunologic agents activate exocytotic mast cell secretion via separate mechanisms.

The influence of verapamil on the gastric effects of stress in rats

The influence of verapamil on stress- or bethanechol-induced gastric effects was investigated in rats. Intraperitoneally injected verapamil (1, 2 or 4 mg/kg), given 30 min beforehand, dose-dependently prevented gastric glandular ulceration, mast cell degranulation and the increased stomach wall contractions evoked by restraint at 4 degrees C for 1 h. Gastric acid secretion, as well as ulceration in both the forestomach and glandular segment, produced by subcutaneously-injected bethanechol (3.2 mg/kg) were also inhibited. It is concluded that decreased amine release from the mast cells, stomach wall relaxation and reduced gastric acid were responsible for the ulcer-antagonising effects of the calcium-entry blocker. The possible antiulcer actions of verapamil are discussed in the light of present knowledge regarding calcium involvement in the various mechanisms thought to contribute to the pathophysiology of stress ulceration in rat stomachs.

Histamine release induced by dynorphin-(1-13) from rat mast cells

Dynorphin is a potent opioid peptide. A synthetic dynorphin-(1-13) (Dyn) induced histamine release accompanied by degranulation from isolated rat mast cells in a dose-dependent manner over the concentration range 10(-7)-10(-5) M. Dynorphin-(1-13)-induced histamine release completed within 10 sec at 37 degrees C, and the release was not accompanied by the leakage of lactate dehydrogenase. Calcium (10(-5)-10(-3) M) enhanced the release, although higher concentration than 10(-3) M suppressed the release. The pH for the maximum release by Dyn was about 7.3. Disodium cromoglycate (5 X 10(-6)-10(-4) M) inhibited the histamine release by Dyn, but naloxone and leucine-enkephalin did not. These results indicate that Dyn-induced histamine release was not mediated by opioid receptors of the mast cells. Its mode of action appeared to that of anaphylactic histamine release.

Sodium-potassium ATPase inhibition potentiates compound 48/80-induced histamine secretion from mast cells

The effect of ouabain on the histamine secretion induced by compound 48/80 has been studied using rat peritoneal mast cells. Ouabain did not modify histamine release in the presence of millimolar concentrations of extracellular calcium. However, when mast cells were previously washed with a calcium-free buffer, ouabain strongly potentiated histamine release elicited by compound 48/80. The full potentiation of mast cell secretion by ouabain required 30 min preincubation before adding compound 48/80. It was inhibited by lanthanum and EGTA. Potassium deprivation mimicked the effect of ouabain. A 30 min preincubation time without potassium was also required. Potassium concentrations below 2.7 mM increased the effect of ouabain whereas higher potassium concentrations reversed this effect. The potentiation of compound 48/80-induced histamine release by ouabain or potassium deprivation was not immediately reversed by washing away ouabain or by adding potassium, respectively. The data confirm that sodium-potassium ATPase is involved, through a calcium-dependent process, in the regulation of histamine release from mast cells.

Calcium requirement for the inhibition by theophylline of histamine release from mast cells

When added to Ca2+-free Hanks' solution, Ca2+ (0.1-2.5 mM) had no significant effect on antigen-induced histamine release from rat mast cells, but Sr2+ (1.0-3.0 mM) dose-dependently increased the release. Ba2+ (1.0 and 2.0 mM) also enhanced the release. Ca2+ and Ba2+ inhibited compound 40/80-induced histamine release, in a dose-dependent manner. In ordinary Hanks' medium, theophylline and 3-isobutyl-1-methylxanthine (IBMX) dose-dependently inhibited the antigen-induced histamine release but these drugs were ineffective in Ca2+-free medium. Theophylline (1.0 mM) also inhibited compound 48/80-induced histamine release in the presence but not absence of Ca2+. There was an optimal Ca2+ concentration for the theophylline effect. Sr2+ but not Ba2+ could substitute for Ca2+ in supporting the theophylline effect. Theophylline (1.0 mM) and IBMX (1.0 mM) increased mast cell cyclic AMP levels both in the presence and absence of Ca2+. These results suggest that Ca2+ is required in the interaction of theophylline and specific sites on mast cells or in the mast cell response to theophylline which probably does not involve the cyclic AMP increase and is linked to the inhibition of histamine release.

Association of 45calcium with rat mast cells stimulated by 48/80: effects of inactivation, calcium and metabolic inhibition

1. Stimulation by compound 48/80 of mast cells deprived of Ca released histamine when Ca was subsequently added. This secretory response was accompanied by a pronounced increase in the amount of cell-associated (45)Ca.2. The level of cell-associated (45)Ca declined as the interval between stimulation by compound 48/80 and the introduction of (45)Ca increased.3. This decline in the amount of (45)Ca paralleled the decline in histamine secretion that is called inactivation and each curve could be fitted by linear regression to a first-order equation with a half-life of between 1 and 2 min.4. When histamine secretion was held constant, the amount of cell-associated (45)Ca steadily and significantly declined as the interval between stimulation and the addition of (45)Ca increased. This decline in the level of (45)Ca was significantly reduced when fully inactivated cells were used.5. The amount of cell-associated (45)Ca could not be significantly reduced by repeated or prolonged washing with EGTA or LaCl(3).6. The addition of the ionphore, A23187, or compound 48/80, to mast cells loaded with (45)Ca by prior stimulation with 48/80 and bathed in Ca-free media, significantly reduced the level of cell-associated (45)Ca. This effect of 48/80 but not of A23187 was prevented by including either dinitrophenol or (45)Ca in the extracellular solution.7. When [(3)H]N-methyl-methoxy-inulin was included with the (45)Ca or added alone, no significant change in the level of cell-associated [(3)H]inulin was found during the course of inactivation.8. Increasing the Ca concentration increased the amount of cell-associated (45)Ca when Ca was added 10 sec after stimulation by 48/80 but not when Ca was added 10 min after stimulation.9. Incubation of mast cells in media containing deoxyglucose and either antimycin A or dinitrophenol prevented both histamine release and any increase in the level of cell-associated (45)Ca in response to stimulation by 48/80. A similar result was obtained using sensitized mast cells stimulated by antigen. The addition of the ionophore, A23187, to the mast cells prompted a significant increase in the level of cell-associated (45)Ca.10. These results are considered to be support for the hypothesis that the process of inactivation to compound 48/80 results from a time-dependent decay in membrane permeability. It is suggested that those events associated with initiating changes in membrane permeability are effected by metabolic inhibition and calcium.