Modulation of histamine secretion from Concanavalin A-activated rat mast cells by phosphatidyl serine, calcium, cAMP, pH and metabolic inhibitors

The lectin ArtinM induces recruitment of rat mast cells from the bone marrow to the peritoneal cavity

Background

The D-mannose binding lectin ArtinM is known to recruit neutrophils, to degranulate mast cells and may have potential therapeutic applications. However, the effect of ArtinM on mast cell recruitment has not been investigated.

Methodology

Male Wistar rats were injected i.p. with ArtinM or ConA (control). The ability of the lectin to degranulate peritoneal and mesenteric mast cells was examined. Recruitment of mast cells to the peritoneal cavity and mesentery after ArtinM injection was examined with or without depletion of peritoneal mast cells by distilled water.

Results

ArtinM degranulated both peritoneal and mesentery mast cells in vitro. Three days after i.p. injection of the lectin there were reduced numbers of mast cells in the peritoneal lavage, while at 7 days post injection of ArtinM, the number of peritoneal mast cells was close to control values. Since immature mast cells are recruited from the bone marrow, the effect of the lectin on bone marrow mast cells was examined. Injection of ArtinM resulted in an increased number of mast cells in the bone marrow. To determine if degranulation of mast cells in the peritoneal cavity was required for the increase in bone marrow mast cells, the peritoneal cavity was depleted of mast cells with ultrapure water. Exposure to ArtinM increased the number of mast cells in the bone marrow of rats depleted of peritoneal mast cells.

Conclusions

The ArtinM induced recruitment of mast cells from the bone marrow to the peritoneal cavity may partially explain the therapeutic actions of ArtinM.

Effects of phosphatidylserine supplementation on exercising humans

Phosphatidylserine (PtdSer) is a ubiquitous phospholipid species that is normally located within the inner leaflet of the cell membrane. PtdSer has been implicated in a myriad of membrane-related functions. As a cofactor for a variety of enzymes, PtdSer is thought to be important in cell excitability and communication. PtdSer has also been shown to regulate a variety of neuroendocrine responses that include the release of acetylcholine, dopamine and noradrenaline. Additionally, PtdSer has been extensively demonstrated to influence tissue responses to inflammation. Finally, PtdSer has the potential to act as an effective antioxidant, especially in response to iron-mediated oxidation. The majority of the available research that has investigated the effects of PtdSer supplementation on humans has concentrated on memory and cognitive function; patients experiencing some degree of cognitive decline have traditionally been the main focus of investigation. Although investigators have administered PtdSer through intravenous and oral routes, oral supplementation has wider appeal. Indeed, PtdSer is commercially available as an oral supplement intended to improve cognitive function, with recommended doses usually ranging from 100 to 500 mg/day. The main sources that have been used to derive PtdSer for supplements are bovine-cortex (BC-PtdSer) and soy (S-PtdSer); however, due to the possibility of transferring infection through the consumption of prion contaminated brain, S-PtdSer is the preferred supplement for use in humans. Although the pharmacokinetics of PtdSer have not been fully elucidated, it is likely that oral supplementation leads to small but quantifiable increases in the PtdSer content within the cell membrane.A small number of peer-reviewed full articles exist that investigate the effects of PtdSer supplementation in the exercising human. Early research indicated that oral supplementation with BC-PtdSer 800 mg/day moderated exercise-induced changes to the hypothalamo-pituitary-adrenal axis in untrained participants. Subsequently, this finding was extended to suggest that S-PtdSer 800 mg/day reduced the cortisol response to overtraining during weight training while improving feeling of well-being and decreasing perceived muscle soreness. However, equivocal findings from our laboratory might suggest that the dose required to undertake this neuroendocrine action may vary between participants.Interestingly, recent findings demonstrating that short-term supplementation with S-PtdSer 750 mg/day improved exercise capacity during high-intensity cycling and tended to increase performance during intermittent running might suggest an innovative application for this supplement. With the findings from the existing body of literature in mind, this article focuses on the potential effects of PtdSer supplementation in humans during and following exercise.

Differential effect of plant lectins on mast cells of different origins

Histamine release induced by plant lectins was studied with emphasis on the carbohydrate specificity, external calcium requirement, metal binding sites, and mast cell heterogeneity and on the importance of antibodies bound to the mast cell membrane to the lectin effect. Peritoneal mast cells were obtained by direct lavage of the rat peritoneal cavity and guinea pig intestine and hamster cheek pouch mast cells were obtained by dispersion with collagenase type IA. Histamine release was induced with concanavalin A (Con A), lectins from Canavalia brasiliensis, mannose-specific Cymbosema roseum, Maackia amurensis, Parkia platycephala, Triticum vulgaris (WGA), and demetallized Con A and C. brasiliensis, using 1-300 microg/ml lectin concentrations applied to Wistar rat peritoneal mast cells, peaking on 26.9, 21.0, 29.1, 24.9, 17.2, 10.7, 19.9, and 41.5%, respectively. This effect was inhibited in the absence of extracellular calcium. The lectins were also active on hamster cheek pouch mast cells (except demetallized Con A) and on Rowett nude rat (animal free of immunoglobulins) peritoneal mast cells (except for mannose-specific C. roseum, P. platycephala and WGA). No effect was observed in guinea pig intestine mast cells. Glucose-saturated Con A and C. brasiliensis also released histamine from Wistar rat peritoneal mast cells. These results suggest that histamine release induced by lectins is influenced by the heterogeneity of mast cells and depends on extracellular calcium. The results also suggest that this histamine release might occur by alternative mechanisms, because the usual mechanism of lectins is related to their binding properties to metals from which depend the binding to sugars, which would be their sites to bind to immunoglobulins. In the present study, we show that the histamine release by lectins was also induced by demetallized lectins and by sugar-saturated lectins (which would avoid their binding to other sugars). Additionally, the lectins also released histamine from Rowett nude mast cells that are free of immunoglobulins.

Roles of intracellular Ca2+ and cyclic AMP in mast cell histamine release induced by radiographic contrast media

Mast cell histamine release is considered to be associated with the etiology of anaphylactoid reactions to iodinated radiographic contrast media (RCM). In the present study, the effects of various ionic and non-ionic RCM on histamine release from mast cells were compared, and the possible mechanisms of the histamine release were subsequently determined. Both ionic (ioxaglate and amidotrizoate) and non-ionic (iohexol, ioversol, iomeprol, iopamidol and iotrolan) RCM increased histamine release from the dissociated rat pulmonary cells, whereby ionic materials were more potent than non-ionic agents. There was no significant correlation between the extent of histamine release and the osmolarity of each RCM solution. In addition, hyperosmotic mannitol solution (1000 mOsm/kg) caused no marked histamine release. Thus, it is unlikely that the hyperosmolarity of RCM solutions contributes to the histamine release. RCM also stimulated, but to a lesser extent, the histamine release from rat peritoneal cells. The RCM-induced histamine release from both types of cells was inhibited by dibutyl cyclic AMP or combined treatment with forskolin and 3-isobutyl-1-methylxanthine. Corresponding to these results, RCM markedly reduced the cellular cyclic AMP content. On the other hand, the removal of intracellular but not the extracellular Ca2+ attenuated the RCM-induced mast cell histamine release. From these findings, it is suggested that the decrease in cellular cyclic AMP content and an increase in intracellular Ca2+ contribute at least in part to the RCM-induced mast cell histamine release.

The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated

The present study examines the effect of concanavalin A (Con A) on the blood insulin and glucose levels of rats. Male and female rats treated with Con A (62.5-500 micrograms/kg) for three days showed a dose- and time-dependent hyperinsulinemia that lasted more than 48 h. Male rats were more sensitive to Con A. Thus, 6 h after treatment with Con A the circulating insulin levels in male rats had increased by 85% (control: 10.2 +/- 0.9 mU/l and Con A-treated: 18.8 +/- 1 mU/l) compared to only 38% (control: 7.5 +/- 0.2 mU/l; Con A-treated: 10.3 +/- mU/l) in females. An identical response was seen after 12 h. Con A (250 micrograms/kg) produced time-dependent hypoglycemia in both sexes but more pronounced in males. There was no correlation between the hypoglycemia and hyperinsulinemia described above. The Con A-induced hyperinsulinemia in rats of both sexes was abolished in gonadectomized animals (intact males: +101 +/- 17% vs orchiectomized males: -5 +/- 3%; intact females: +86 +/- 23% vs ovariectomized females: -18 +/- 7.2%). Pretreating intact male and female rats with human chorionic gonadotropin also significantly inhibited the Con A-induced hyperinsulinemia. Estradiol (10 micrograms/kg,i.m.) significantly blocked the Con A-induced increase in circulating insulin in male rats (101 +/- 17% for controls vs 32 +/- 5.3% for estradiol-treated animals, P < 0.05) while testosterone (10 mg/kg, i.m.) had no similar effect on intact female rats. Pretreating Con A-injected rats with opioid antagonists such as naloxone (1 mg/kg, s.c.) and naltrexone (5 mg/kg, s.c.) blocked the hyperinsulinemia produced by the lectin in males (control: +101 +/- 17% vs naloxone-treated: +5 +/- 14%, or naltrexone-treated: -23 +/- 4.5%) and females (control: +86 +/- 23% vs naloxone-treated: +21 +/- 20%, or naltrexone-treated: -18 +/- 11%). These results demonstrate that Con A increases the levels of circulating insulin in rats and that this response is opioid-dependent and hormonally regulated.

Characteristics of the histamine release from hamster cheek pouch mast cells stimulated by lectins from Brazilian beans and concanavalin A

We have characterized the histamine releasing effects of lectins extracted from Brazilian beans, in comparison to concanavalin A, in hamster cheek pouch cell suspensions containing mast cells. The lectins from Dioclea virgata, Canavalia brasiliensis, and Dioclea rostrata induce histamine release in a similar manner to concanavalin A, but appear to differ in potency and efficacy. The effects depended on the temperature, pH, and metabolic energy, demonstrating the non-cytotoxic nature of the histamine release. It is suggested that the lectins studied act by the same mechanism as concanavalin A (interacting with sugars in the antibodies bound to the mast cells), since high concentrations of glucose inhibit the histamine release. The lectins at high concentrations quench the histamine release. This suppression is reversed by increasing calcium concentration, suggesting that the lectins bind to the calcium that is essential for the secretion, thereby confirming and extending our previous data using the lectin from Dioclea virgata in rat peritoneal mast cells.

Histamine release induced by glucose (mannose)-specific lectins isolated from Brazilian beans. Comparison with concanavalin A

The histamine releasing properties of glucose (mannose)-specific lectins isolated from Brazilian beans was examined. The Canavalia brasiliensis, Dioclea rostrata, and Dioclea virgata lectins induced histamine release in rat peritoneal mast cells similar to concanavalin A. Less potency and efficacy was observed for Canavalia maritima, Dioclea guianensis, and Dioclea violacea while very low activities were seen for the lectins from Dioclea grandiflora, Canavalia bonariensis, and Cratylia floribunda. The histamine releasing effect was quenched by higher doses of D. virgata lectin similar to what was reported for concanavalin A. This effect was abrogated by increasing the concentration of calcium in the incubating medium. As these above proteins have sites that bind calcium, higher doses of the lectins might withdraw the calcium which is essential for the mast cell secretion.

Canatoxin triggers histamine secretion from rat peritoneal mast cells

Canatoxin, a toxic protein present in the seeds of Canavalia ensiformis, induces the secretion of serotonin, dopamine and insulin through activation of the lipoxygenase pathway. The purpose of the present study was to verify if canatoxin causes histamine release from rat peritoneal mast cells and to perform a detailed study of this phenomenon. Our results indicate that canatoxin is capable of activating mast cells to release histamine. The process is time- and concentration-dependent, occurs without cell damage and requires metabolic energy as well as the presence of divalent cations (Ca2+ and Mg2+). Optimal release occurs at 37 degrees C and at physiological pH. Extremes of temperature (0 degree C and 45 degrees C) inhibit the process. We conclude that canatoxin induces histamine release from rat peritoneal mast cells by an active secretory process.

Active sensitization does not increase the responsivity of rat peritoneal mast cells to diverse chemical stimuli

Peritoneal mast cells from specific pathogen-free rats that had been sensitized to the nematode Nippostrongylus brasiliensis released histamine in a dose-dependent fashion on challenge with antigen, anti-rat IgE, anti-rat IgG and concanavalin A. Cells from non-sensitized animals showed weak or insignificant responses to these agents. However, the two preparations did not obviously differ in their reactivity to a range of pharmacological agents including ATP, dextran, polyamines and calcium ionophores. Both populations were refractory to cholinergic stimulation. These results show that active sensitization does not per se lead to a global increase in mast cell reactivity or releasability.

The actions of retinal and retinoic acid on histamine release from rat peritoneal mast cells

Histamine release from rat peritoneal mast cells induced by anti-IgE was potentiated by the retinoids: retinoic acid 2-10 microM and retinal 1-5 microM. Retinal also produced a concentration-dependent increase in anti-IgE-stimulated 45Ca uptake by these mast cells. A similar potentiating action of both retinoids was observed on histamine release induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). For both anti-IgE- and TPA-induced histamine release, the potentiating effect of the two retinoids was only observed in the presence of extracellular calcium. In contrast, histamine release induced by compound 48/80 was inhibited by retinal 1-5 microM and by retinoic acid 10-50 microM and the inhibition was the same in the presence as in the absence of extracellular calcium 1 mM. Histamine release induced by calcium and the calcium ionophore A 23187 was inhibited by retinoid acid 2-10 microM and by retinal 10 microM. Inhibitions of compounds 48/80-induced histamine release by cromoglycate and by retinal were additive. It is concluded that while the actions of retinoids on rat peritoneal mast cells are consistent with the inhibition of protein kinase C, another action of these compounds, unrelated to this enzyme, may explain the data.

The role of a Ca2+/calmodulin dependent plasma membrane Ca2+ channel during concanavalin A activation of MC9 mast cells

The effects of Con A on free cytoplasmic calcium concentrations in the cloned murine mast cell, MC9, have been measured using the fluorescent calcium indicator quin 2. Con A causes a rapid, small yet sustained rise in free cytosolic calcium (up to 245 nM) followed closely by increased 45calcium uptake and more slowly by histamine release. The increases in 45calcium uptake and histamine release require extracellular calcium. However, the Ca2+ influx blockers, nifedipine and verapamil inhibit these responses only at concentrations significantly higher than those used in smooth muscle to oppose potential-dependent events, and diltiazem is inactive. These observations suggest that, in these mast cells, other types of channels control Ca2+ entry. In contrast, the intracellular Ca2+ blocker, TMB-8, inhibits both the Con A-induced histamine release and the Ca2+ changes. The calmodulin antagonists calmidazolium, trifluoperazine and W-7 are also highly effective inhibitors of both the Ca2+ changes and histamine release in direct proportion to their potency against calmodulin-dependent phosphodiesterase, implicating calmodulin in the regulation of stimulus-secretion in MC9 cells. These data imply that histamine release follows increases in intracellular Ca2+ concentration. Free intracellular Ca2+ results from rapid release from internal stores and is followed by a slower but more sustained influx of extracellular Ca2+.

Rat mast cell activation and inactivation: differences when various ligands are used to induce secretion

The relationship between rat peritoneal mast cell activation and inactivation (desensitization) was studied for a variety of stimuli acting via IgE and IgG receptors on the cell surface. Anti-IgE, antigen (ovalbumin), anti-IgG1, anti-IgG2a and dimers, trimers and higher oligomers of IgE were used to induce histamine release from rat mast cells. All produced similar characteristics of cell activation, with a rapid rate of histamine release from the cells, release being 90% complete within 5 minutes and with calculated doubling times between 21.6 +/- 3.6 s (+/- SEM) for ovalbumin and 93.0 +/- 18.6 s (+/- SEM) for anti-IgG1. The characteristics of inactivation, however, varied with the releasing agent used. Of all the stimuli used only ovalbumin showed a rapid rate of desensitization (t 1/2 = 330 +/- 34.8 s) which correlated with the cessation of histamine release. The other stimuli showed slow rates of desensitization (t 1/2 between 1068 +/- 40.2 s for dimer and 3576 +/- 660 s for anti-IgE) even though the rate of release was rapid. Thus, although these stimuli are thought to be stimulating the cells by cross-linking of either IgE or IgG receptors, the difference in subsequent response of the cells would indicate that the transduction mechanism bringing about release can distinguish between these various stimuli. Also, it seems that the idea that duration of histamine release is determined by the rate of desensitization may need revising as with most of these stimuli, release has terminated when the cells are still in a fully activated state.

Characteristics of histamine release from isolated rat mast cells: differences when various ligands are used to induce secretion

Differences are reported in the response of rat peritoneal mast cells to three releasing agents: ovalbumin, to which the rats were actively sensitized, anti-IgE, an immunoglobulin directed against the rat IgE molecule, and IgE chemically dimerized with suberimidate. Both the rate of histamine release and the rate of desensitization were measured for each of the three ligands. The calculated doubling times for the rates of histamine release due to ovalbumin, anti-IgE and dimer were 19.6 sec, 168 sec and 37.7 sec respectively. The calculated half-lives for the rate of desensitization due to ovalbumin, anti-IgE and dimer were 348 sec, 5900 sec and 3450 sec respectively. The three ligands are all believed to act by crosslinking Fc receptors on the cell surface but the pattern of responses obtained varied with the ligand used. It is proposed that some component of the transduction mechanism linking the stimulus to the cell to the subsequent response can distinguish between the various sizes or conformations of Fc receptor aggregates formed on the cell surface.

Histamine-releasing properties of mast cells from various strains of mice

A comparison has been made of the in vitro histamine releasing capacity of peritoneal mast cells from BALB/c, C3H/A, C57BL/6J and CFW mouse strains in response to immunological and non-immunological stimuli namely anti-mouse IgE, Concanavalin A (Con A), ionophore A23187 and sodium fluoride. Anti-IgE-induced histamine secretion was highest in mast cells of CFW mice, intermediate in the cells of C57BL/6J and C3H/A mice and lowest in the cells of BALB/c mice. Similar, although less pronounced, strain-dependent differences were observed in Con A-induced release. Mast cells of C57BL/6J and CFW mice were significantly more sensitive to the action of ionophore A23187 compared to the two other strains, although the cells of each strain responded in different manner. Sodium fluoride-induced histamine release occurred in two ways: from mast cells of BALB/c and C57BL/6J it was dose-dependent at NaF concentrations of 1-15 mM, whereas cells of the two other strains were insensitive to the action of NaF at concentrations of 1-5 mM but at a concentration of 7.5 mM, a very strong potentiation of release was observed. Our results suggest functional heterogeneity of mast cells from various strains of mice, a point to be considered in further studies of mast cell function.

Inhibition by disodium cromoglycate of anaphylactic histamine secretion from rat peritoneal mast cells in the presence of phosphatidylserine

The lipid phosphatidylserine (PS) markedly potentiated anaphylactic histamine secretion from isolated rat peritoneal mast cells in the presence of extracellular calcium ions. The compound correspondingly reduced the inhibitory effect of disodium cromoglycate on the secretion induced by optimal concentrations of antigen. However, at a constant concentration of PS, suboptimal amounts of antigen were effectively inhibited by the drug. The inhibitory power of cromoglycate increased as the concentration of antigen was decreased and the corresponding control release of histamine declined. At control values similar to those observed without addition of PS, the drug inhibited secretion to a similar extent as in the absence of the lipid. At given concentrations of PS and antigen, the potency of the drug increased with decreasing degrees of sensitization of the experimental animals. These effects are not likely to reflect a direct interaction between the drug and PS since increasing the concentration of the lipid by one hundred-fold did not affect the inhibitory effect of the chromone. Further, the latter was essentially equiactive in the presence and absence of PS in calcium-free media, conditions under which the lipid did not enhance histamine release. These results are discussed in terms of the proposed modes of action of PS and cromoglycate.

Anti-IgE and Con A-induced histamine release from mast cells of four rat strains: correlation with total serum IgE

Anti-IgE- and Con A-induced histamine release from serosal mast cells were compared to each other and to total serum levels of IgE in non-immunized, alum-injected, and Silica gel-injected rats of the BN, Fischer, PVG, and SD strains. The results indicate that the degree of anti-IgE- and Con A-induced release is strain-dependent and varies with immunization conditions. Furthermore, there is a gross but not complete correlation between the degree of serosal mast cell histamine release induced by the two secretagogues. However, Con A- or anti-IgE-induced release could significantly be correlated to serum levels of total IgE only in the Fischer strain but not in the BN or the PVG strains. In the SD strain, Con A-induced release correlated to serum IgE levels in Silica gel-injected but not in alum-injected animals.

IgG receptors on the mast cells

Antisera to the IgG subclasses, 1, 2a, 2b, and 2c, induced histamine release from mast cells obtained from the peritoneal washings of Lister hooded rats. The maximum responses obtained with anti-IgG1 and anti-IgG2a were as great as that for anti-IgE (more than 60% histamine release). Cells from unresponsive Wistar rats which did not secrete appreciable amounts of histamine in response to any of the antisera, produced on active sensitization with ovalbumin a small but significant response on challenge with anti-IgG1 and anti-IgG2b as well as with anti-IgE. Passive sensitization with rat myeloma serum of mast cells from the unresponsive rats produced a large response on challenge with anti-IgE but no release to the anti-IgG group 2 subclasses. IgE myeloma serum (1:1000) neutralized the histamine-releasing activity on anti-IgE serum (87% inhibition) and the antisera to all subclasses of IgG. When the IgE in the myeloma serum was inactivated by heating, the response to the IgG antisera remained completely inhibited except for anti-IgG2a where some reversal was observed. When purified myeloma IgE (30 microgram/ml) was used in place of whole serum, marked inhibition (86%) of the response to anti-IgE was obtained leaving the responses to the IgE subclasses unaffected (except for IgG2a, which was 65% inhibited).

Effect of lanthanide ions on histamine secretion from rat peritoneal mast cells

1 Ions of the lanthanide series (lanthanum-lutetium) inhibit histamine release induced by allergen and anti-IgE in the presence of extracellular calcium. The inhibition is dose-dependent in the range 10(-6) to 10(-9) M and there is no marked difference in potency between the lanthanides. 2 The response to lanthanum is biphasic and higher concentrations (10(-4) M) potentiate the release. Maximal concentrations (10(-3) M) again abolish secretion. 3 The effect of concanavalin A is weakly antagonized by lanthanum but strongly inhibited by higher lanthanides. 4 Inhibition of histamine release evoked by basic agents is markedly dependent on the ionic radius of the lanthanide. In the presence of extracellular calcium, dysprosium is the most effective inhibitor. Similar results are observed with dextran. In the absence of calcium, there is a regular increase in inhibition with decreasing ionic radius. 5 Inhibition of release in the presence of calcium is immediate and does not require preincubation with the lanthanide. The antagonism due to lanthanum is competitive and the pA2 values vary with the secretagogue. In contrast, the inhibitory effect in the absence of extracellular calcium increase progressively with time. 6 These results are discussed in terms of the calcium-pools important in histamine release and the mode of action of different secretagogues.