Histamine release from human basophils induced by platelet activating factor: the role of extracellular calcium, interleukin-3, and granulocyte-macrophage colony-stimulating factor

Concurrent blockade of platelet-activating factor and histamine prevents life-threatening peanut-induced anaphylactic reactions

BACKGROUND

Food anaphylaxis is an acute and life-threatening systemic allergic reaction. Fatality registries place peanut as the most common culprit of fatal and near-fatal reactions in North America. Because prophylaxis and treatment have advanced little in recent years, it is imperative to evaluate novel therapies.

OBJECTIVE

To investigate the impact of blocking mast cell mediators in a mouse model of peanut-induced anaphylaxis.

METHODS

Mice were sensitized with peanut protein and cholera toxin via oral gavage weekly for 4 weeks. One week after the last sensitization, separate groups of mice were treated with either a (1) 5-lypoxygenase inhibitor, (2) a platelet-activating factor (PAF) receptor antagonist, (3) histamine receptor antagonists, or (4) a PAF receptor antagonist along with histamine receptor antagonists before peanut challenge.

RESULTS

Treatment targeting either leukotrienes or histamine alone had no beneficial effects. In contrast, PAF antagonism significantly attenuated the magnitude and duration of the anaphylactic reactions. Particularly, it prevented severe reactions. Moreover, 83% of PAF-treated versus 43% of untreated mice reached recovery within 120 minutes after peanut challenge. Notably, combined blockade of PAF and histamine had a clearly greater beneficial effect. In fact, all but 1 mouse developed mild, if any, anaphylactic reactions. In addition, combination therapy was associated with a significant decrease in vascular leakage and release of vasoactive mediators after peanut challenge.

CONCLUSION

Combination therapy blocking both PAF and histamine markedly reduces the severity of peanut-induced anaphylaxis, and thus it may be a potential life-saving therapeutic approach in peanut and, likely, other food-induced anaphylaxis.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Suppressive activity of epinastine hydrochloride on TARC production from human peripheral blood CD4+ T cells in-vitro

Thymus- and activation-regulated chemokine (TARC) is an important molecule in the development and maintenance of allergic diseases. However, there is little information about the influence of anti-allergic agents on TARC production. The aim of this study is to examine the influence of epinastine hydrochloride, an H1-receptor antagonist, on TARC production from human peripheral blood CD4+ T cells using an in-vitro cell culture technique. CD4+ T cells prepared from healthy subjects were cultured in wells coated with a combination of OKT3 and anti-CD28 monoclonal antibody in the presence or absence of epinastine HCl for 24 h. The cells were also stimulated with interleukin (IL)-4 in a similar manner. Levels of TARC and IL-4 in culture supernatants were examined by ELISA. The addition of epinastine HCl exerted a dose-dependent suppressive effect on the production of both TARC and IL-4 from CD4+ T cells under co-stimulatory molecule stimulation. The minimum concentration of the agent showing a significant suppressive effect on TARC and IL-4 production was 5.0 microM and 2.5 microM, respectively. Epinastine HCl also suppressed the ability of cells to produce TARC in response to IL-4 stimulation, when the agent was added to cell cultures at more than 2.5 microM. It was concluded that this inhibitory action of epinastine HCl may be partially responsible for epinastine's attenuating effect on allergic diseases.

5-Oxo-6,8,11,14-eicosatetraenoic acid is a potent chemoattractant for human basophils

BACKGROUND

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is a chemoattractant for eosinophils and neutrophils, and the messenger RNA for its receptor, the oxo-eicosatetraenoic acid receptor (OXE), has been detected in several tissues.

OBJECTIVES

This study aimed at clarifying the role of 5-oxo-ETE in the regulation of basophil function.

METHODS

Basophil responses were determined in assays of flow-cytometric shape change, Ca(2+) flux, chemotaxis, and histamine release. Messenger RNA for OXE was detected by real-time PCR.

RESULTS

We observed that human eosinophils were 3 to 10 times more sensitive to 5-oxo-ETE than neutrophils in flow-cytometric shape change and Ca(2+) flux assays, as estimated from the half-maximal responses of the cells. Basophils responded to 5-oxo-ETE in the shape change assay with a sensitivity similar to that of eosinophils. 5-Oxo-ETE was a weak inducer of Ca(2+) flux in basophils and did not cause histamine release but was a highly effective chemoattractant for basophils in the low nanomolar concentration range in a pertussis toxin-sensitive manner. In agreement with these functional studies, the messenger RNA for the 5-oxo-ETE receptor, OXE, was detectable in basophils as in monocytes, eosinophils, and neutrophils, but not in fibroblasts. Specimens from sinus mucosa, tonsils, and adenoids also contained detectable levels of messenger RNA for OXE.

CONCLUSION

Our data suggest that 5-oxo-ETE is potentially involved in the regulation of basophil recruitment and might hence be a useful therapeutic target in atopic disease.

Pharmacological Stabilization of Mast Cells Abrogates Late Thrombotic Events Induced by Diesel Exhaust Particles in Hamsters

Background— Particulate air pollution is associated with cardiovascular diseases and myocardial infarction (MI).

Methods and Results— We investigated the relationship between airway inflammation and thrombosis 24 hours after intratracheal (IT) instillation of diesel exhaust particles (DEP; 50 μg/hamster). Mild thrombosis was induced in the femoral vein by endothelial injury, and the consequences of airway inflammation on thrombogenicity were studied via online video microscopy. Lung inflammation and histamine analysis in bronchoalveolar lavage (BAL) and plasma were performed after pretreatment with dexamethasone (DEX) or sodium cromoglycate (SC). DEP induced airway inflammation and histamine release in BAL and in plasma, and increased thrombosis, without elevating plasma von Willebrand factor (vWF) levels. The IT instillation of 400-nm positively charged polystyrene particles (500 μg/hamster), serving as particles that do not penetrate into the circulation, equally produced airway inflammation, histamine release, and enhanced thrombosis. Histamine in plasma resulted from basophil activation. Intraperitoneal (IP) pretreatment with DEX (5 mg/kg) abolished the DEP-induced histamine increase in BAL and plasma and abrogated airway inflammation and thrombogenicity. The IT pretreatment with DEX (0.5 mg/kg) showed a partial but parallel inhibition of all of these parameters. Pretreatment with SC (40 mg/kg, IP) strongly inhibited airway inflammation, thrombogenicity, and histamine release.

Conclusions— Our results are compatible with the triggering of mast cell degranulation and histamine release by DEP. Histamine plays an initial central role in airway inflammation, further release of histamine by circulating basophils, and peripheral thrombotic events. Antiinflammatory pretreatment can abrogate the peripheral thrombogenicity by preventing histamine release from mast cells.

Increase in granulocyte-macrophage-colony-stimulating factor secretion and the respiratory burst with decreased L-selectin expression in hyper-IgE syndrome patients

BACKGROUND

The hyper-IgE syndrome is a primary immunodeficiency characterized by severe recurrent abscesses, pneumonia with pneumatocele formation, and elevated serum IgE. Eosinophilia, neutrophil chemotactic defects, and marked tissue damage are frequently present in this syndrome.

OBJECTIVE

To study whether functional changes in cytokines, adhesion molecules, and neutrophils might help explain these clinical observations.

METHODS

The following functions were analyzed in patients with the hyper-IgE syndrome and in controls: (1) production of granulocyte-macrophage-colony-stimulating factor by peripheral blood mononuclear cells by ELISA; (2) respiratory burst and reactive oxygen intermediates production by peripheral neutrophils using the luminol-enhanced chemiluminescense technique; and (3) expression of L-selectin on granulocytes and lymphocytes by flow cytometry.

RESULTS

Patients with hyper-IgE syndrome had significantly increased production of granulocyte-macrophage-colony-stimulating factor by resting or stimulated mononuclear cells, increased generation of reactive oxygen intermediates by neutrophils treated with opsonized zymosan, and reduced L-selectin expression on quiescent and activated granulocytes and lymphocytes.

CONCLUSIONS

Our results suggest that an important feature of the hyper-IgE syndrome is the increased production of granulocyte-macrophage-colony-stimulating factor, which may explain the reduced L-selectin expression, decreased chemotaxis, and increased oxygen radical production and tissue damage in this disease.

Granulocyte-macrophage colony-stimulating factor enhances interleukin-1beta stimulated histamine release in the preovulatory rat ovary

The existence of immune cells including macrophages and mast cells in rat ovary implies that various cytokines from these cells may play a role in ovarian functions. The aim of the present study was to investigate whether granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-1beta are capable of stimulating histamine release and steroidogenesis in rat ovary, and to determine the sites of histamine production in the ovary. Histamine release from preovulatory ovarian tissues was stimulated in a dose-dependent manner at 3-30 ng/ml of GM-CSF in the presence of interleukin-1beta (10 ng/ml). However, treatment with GM-CSF and interleukin-1beta did not cause any significant change in the levels of ovarian steroids. Intense staining of histidine decarboxylase in the ovary was immunohistochemically detected in large granular cells on the morning of the pro-oestrus day. These results indicate that GM-CSF may be involved in the regulation of ovarian histamine secretion in mast cells partially by enhancing interleukin-1beta-induced histamine release in the process of ovulation.

Secretion of proinflammatory cytokines by human conjunctival epithelial cells

The production of cytokines by human conjunctival epithelial cells following stimulation was investigated. Primary cultures of human conjunctival epithelial cells were characterized by morphology and keratin expression. Cultured epithelial cells were treated with varying concentrations of lipopolysaccharide, interleukin (IL)-1 beta, calcium ionophore A23187, or phorbol myristate acetate, and cytokine secretion was determined over specified intervals. Culture supernatants and cell lysates were analyzed by ELISA for IL-1 beta, IL-3, IL-4, IL-5, IL-6, IL-8, IL-11, IL-1 receptor antagonist (IL-1ra), tumor necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony stimulating factor (GM-CSF). With the exception of IL-1ra, unstimulated conjunctival epithelial cells produced cytokines at relatively low or undetectable levels. IL-1ra was detected in both culture supernatants and cell lysates under basal conditions. In response to stimuli, conjunctival epithelial cells secreted the proinflammatory cytokines TNF-alpha, IL-6, IL-8, and GM-CSF in a dose- and time-dependent fashion. After stimulation, the intracellular levels of IL-1ra increased in these cells but the supernatant-associated levels remained unchanged. None of the other cytokines evaluated (IL-1 beta, IL-3, IL-4, IL-5, and IL-11) were detected in supernatants or lysates of resting or stimulated cells. These findings suggest that conjunctival epithelial cells may contribute to the pathogenesis of human ocular diseases by production of proinflammatory cytokines. Further evaluation of these cells as targets of therapy is warranted.

Platelet-activating factor induces histamine release from human skin mast cells in vivo, which is reduced by local nerve blockade

BACKGROUND

Intradermal injection of platelet-activating factor (PAF) causes wheal and flare reactions, which are inhibited by antihistamines. However, PAF does not release histamine from human dispersed skin mast cells in vitro. The purpose of this study was to investigate the extent and possible mechanisms of PAF-induced histamine release in human skin in vivo with the use of dermal microdialysis.

METHODS

Hollow dialysis fibers were inserted into the upper dermis in forearm skin and each fiber was perfused with Krebs-Ringer bicarbonate solution at a rate of 3.0 microliters/min. PAF (4.5 to 36 mumol/L), lyso-PAF (36 mumol/L), vehicle (negative control), and codeine 750 or 250 mumol/L (positive control) were injected intradermally above separate fibers. Dialysate was collected in 2-minute fractions for 20 minutes and histamine analyzed spectrofluorometrically.

RESULTS

PAF, but not lyso-PAF, caused statistically significant dose-related histamine release and wheal and flare reactions. Intradermal mepivacaine administration significantly abrogated flare reactions by PAF and codeine and inhibited histamine release and wheal reactions by PAF but not by codeine. Long-term topical capsaicin administration inhibited histamine release and wheal reactions by PAF but not by codeine. It inhibited flare reactions induced by both compounds. PAF did not release histamine from blood basophils.

CONCLUSIONS

These data suggest that PAF induced histamine release from mast cells in intact human skin indirectly via neurogenic activation. Further, on the intradermal injection of PAF histamine release and the skin responses, the wheal and the flare, are differentially regulated by neurogenic components.

Histamine-releasing factors

There is increasing evidence that human basophils accumulate at sites of chronic inflammation, and, in particular, in allergic asthma. Investigators have, therefore, become very interested in identifying proteins that activate these cells. Recently, the gene encoding a candidate for this function, a novel molecule, the IgE-dependent histamine-releasing factor, was cloned.