Different modulation by histamine of IL-4 and interferon-gamma (IFN-γ) release according to the phenotype of human Th0, Th1 and Th2 clones

Histamine, an important inflammatory mediator in allergic diseases and asthma, has been reported to have modulator effects on T cells, suggesting that the bronchial microenvironment may regulate the function of resident T cells. We examined the effect of histamine on the release of the Th2-associated cytokines IL-4 and IL-5 and the Th1-associated cytokine IFN-γ by 30 CD4⁺ T cell clones from peripheral blood or bronchial biopsy of one atopic subject. Based on the IL-4/IFN-γ ratio, the clones were ascribed to the Th2 (ratio >1), Th0 (ratio 0.1 and 1) or Th1 (ratio <0.1) phenotype. Histamine inhibited IFN-γ production by Th1-like cells (P<0.02, Kruskall–Wallis), especially from bronchial biopsy, but had no effect on IL-4 release. Regarding Th0 clones, histamine inhibited IL-4 production (P<0.02) in a dose-dependent manner and slightly inhibited IFN-γ production, but had no effect on Th2-like cells. Histamine had a heterogeneous and insignificant effect on IL-5 production. The H₂-receptor antagonist ranitidine completely reversed the inhibition of IL-4 and IFN-γ production, whereas the agonist dimaprit mimicked this effect. In contrast, H₁- and H₃-receptor agonists and antagonists had no significant effect. These data demonstrate that histamine has different effects on IL-4 and IFN-γ release by T helper cells according to their phenotype via H₂-receptors. This study extends the immunomodulatory effects of histamine which may contribute to the perpetuation of airway inflammation in asthma.     

Effects of aminoguanidine and L-NAME on histamine-induced blood pressure drop in the rat

Mean arterial blood pressure changes in response to i.v. administration of histamine were monitored in the anaesthetized rat in the absence or presence of the diamine oxidase (DAO) inhibitor aminoguanidine (AMG, 10 mg kg^?1). AMG prolonged the duration of the transient drop in blood pressure induced by a bolus injection of histamine (0.05 mg kg^?1) by 34%. In animals pretreated with AMG, no potentiation of the decrease in pressure in response to a 10 min infusion of histamine was observed. However, when infusion was stopped, the time needed for pressure recovery was twice as long in animals treated with AMG as in controls. Blood samples were taken prior to infusion and during the recovery phase and the quantities of histamine were determined by liquid chromatography. The prolonged recovery phase observed in animals pretreated with AMG was associated with five times higher levels of histamine. The duration of histamine-induced hypotension (0.01 mg kg^?1) was 50% shorter in the presence of the nitric oxide synthase inhibitor L -NAME (10 mg kg^?1). We suggest that DAO, through elimination of histamine from the bloodstream, is important for the recovery from histamine-induced hypotension, and that the duration of histamine-induced pressure drop is influenced by formation of nitric oxide.     

Mast cell activation markers for in vitro study

ABSTRACT

Mast cells (MCs) are well known for their role in allergic conditions. This cell can be activated by various types of secretagogues, ranging from a small chemical to a huge protein. Mast cell activation by secretagogues triggers the increase in intracellular calcium (iCa²⁺) concentration, granule trafficking, and exocytosis. Activated mast cells release their intra-granular pre-stored mediator or the newly synthesized mediator in the exocytosis process, in the form of degranulation or secretion. There are at least three types of exocytosis in mast cells, which are suggested to contribute to the release of different mediators, i.e.,, piecemeal, kiss-and-run, and compound exocytosis. The status of mast cells, i.e., activated or resting, is often determined by measuring the concentration of the released mediator such as histamine or β-hexosaminidase. This review summarizes several mast cell components that have been and are generally used as mast cell activation indicator, from the classical histamine and β-hexosaminidase measurement, to eicosanoid and granule trafficking observation. Basic principle of the component determination is also explained with their specified research application and purpose. The information will help to predict the experiment results with a certain study design.     

Differential modulation of mediator release from human basophils and mast cells by mizolastine

BACKGROUND: Basophils and mast cells play a major role in the pathogenesis of allergic disorders by releasing several proinflammatory mediators. Some histamine H1 receptor antagonists exert anti-inflammatory activities by modulating mediator release from basophils and mast cells. OBJECTIVE: To study the in vitro effects of mizolastine, an H1 receptor antagonist, on the release of eicosanoids, histamine and IL-4 from human basophils and lung mast cells. METHODS AND RESULTS: Mizolastine (10(-7)-10(-5) M) concentration-dependently inhibited the release of cysteinyl leukotriene C4 from anti-IgE-stimulated basophils (IC(50): 3.85+/-0.28 microM) and mast cells (IC(50): 3.92+/-0.41 microM). The same concentrations of mizolastine did not affect anti-IgE-induced prostaglandin D2 release from lung mast cells. In contrast, mizolastine enhanced up to 80% IgE-mediated histamine release (EC(50): 4.63+/-0.14 microM) from basophils, but not from mast cells and it significantly potentiated IL-4 release from basophils induced by anti-IgE. Mizolastine did not affect histamine release from basophils induced by formyl peptide, whereas it inhibited cysteinyl leukotriene C4 release (IC(50): 1.86+/-0.24 microM). Blockade of cytosolic phospholipase A2 and arachidonic acid mobilization by pyrrolidine-1 did not alter the effect of mizolastine on histamine release from basophils, thereby excluding accumulation of arachidonic acid metabolic intermediates as the cause of this effect. Mizolastine did not influence anti-IgE-induced activation of extracellular signal-regulated kinase-1 and -2 (ERK-1 and -2) in human basophils. CONCLUSIONS: Mizolastine efficiently inhibits LTC4 synthesis in human basophils and mast cells presumably by interfering with 5-lipoxygenase. In contrast, it enhances histamine and IL-4 release only from anti-IgE-stimulated basophils. Therefore, mizolastine differentially regulates the production of mediators from basophils and mast cells in a cell- and stimulus-specific fashion.     

Allergic bronchial asthma: eosinophil chemotaxis and antihistaminic drug modulation

This paper investigated the chemotactic capacity of blood eosinophils (EOS) in response to C5a and formyl-leucyl-phenylalanine (FMLP) in 15 Parietaria- pollen-allergic patients with mild asthma during the Parietaria pollen season. Data showed that EOS chemotaxis toward C5a was significantly reduced during the peak pollen count, compared with the values obtained in normal subjects. On the other hand, FMLP could induce EOS chemotactic activity only in Parietaria- allergic patients, the highest value being registered during the height of the Parietaria season. In vitro cimetidine modulation of chemotactic function in comparison with C5a led to a recovery of the impaired results obtained in the presence of high histamine levels. Moreover, diphenhydramine preincubation of EOS induced a reduction of the enhanced chemotactic activity obtained with low concentrations. The data suggest that different serum histamine levels give rise to an impaired immune-phlogistic response in allergic patients and that histamine-receptor antagonists may modulate this effect.     

Involvement of human histamine N-methyltransferase gene polymorphisms in susceptibility to atopic dermatitis in korean children

Purpose

Histamine N-methyltransferase (HNMT) catalyzes one of two major histamine metabolic pathways. Histamine is a mediator of pruritus in atopic dermatitis (AD). The aim of this study was to evaluate the association between HNMT polymorphisms and AD in children.

Methods

We genotyped 763 Korean children for allelic determinants at four polymorphic sites in the HNMT gene: -465T>C, -413C>T, 314C>T, and 939A>G. Genotyping was performed using a TaqMan fluorogenic 5'' nuclease assay. The functional effect of the 939A>G polymorphism was analyzed.

Results

Of the 763 children, 520 had eczema and 542 had atopy. Distributions of the genotype and allele frequencies of the HNMT 314C>T polymorphism were significantly associated with non-atopic eczema (P=0.004), and those of HNMT 939A>G were significantly associated with eczema in the atopy groups (P=0.048). Frequency distributions of HNMT -465T>C and -413C>T were not associated with eczema. Subjects who were AA homozygous or AG heterozygous for 939A>G showed significantly higher immunoglobulin E levels than subjects who were GG homozygous (P=0.009). In U937 cells, the variant genotype reporter construct had significantly higher mRNA stability (P<0.001) and HNMT enzyme activity (P<0.001) than the common genotype.

Conclusions

Polymorphisms in HNMT appear to confer susceptibility to AD in Korean children.     

Interleukin‐8 inhalation directly provokes bronchoconstriction in guinea pigs

BACKGROUND: Although it has been reported that the concentration of interleukin (IL)-8 in nasal lavage fluid and sputum and its production in bronchial epithelium were increased in asthmatic subjects, the direct effects of IL-8 on the airways in vivo is unclear. METHODS: We examined bronchoconstriction in response to IL-8 inhalation through an endotracheal cannula in anesthetized, artificially ventilated guinea pigs. RESULTS: Inhalation of IL-8 at concentrations of 1 and 10 microg/ml caused significant bronchoconstriction, as revealed by the elevation of pressure at the airway opening. Moreover, the bronchoconstriction induced by IL-8 was significantly inhibited by the antihistamines diphenhydramine and terfenadine, suggesting the involvement of histamine release in the IL-8-induced bronchoconstriction. No significant leukocyte infiltration was observed in the bronchoalveolar lavage fluid or histologic findings 25 min after the first IL-8 inhalation. CONCLUSIONS: IL-8 provokes bronchoconstriction without leukocyte accumulation in the airways, mediated in part by histamine release, in guinea pigs.     

Amaranthus spinosus Linn. inhibits mast cell-mediated anaphylactic reactions

The current study characterizes the mechanism by which the Amaranthus spinosus (Amaranthaceae) decreases mast cell-mediated anaphylactic reactions. Anaphylaxis is a typical hypersensitivity Type I reaction, sharing common mechanisms with asthma in its early and late phases. Mast cells are key as effector cells in hypersensitivity Type I reactions. A. spinosus has been traditionally used in the treatment of allergic bronchitis and asthma, but its role in mast cell-mediated anaphylactic reactions has not fully been investigated. This report investigated the potential effects of the ethyl acetate fraction of A. spinosus leaves (EAFAS) against a Compound 48/80 (potent secretagogue)-induced systemic anaphylactic shock paradigm in a mouse model. In addition, rat peritoneal mast cells (RPMC) were used in in vitro studies to investigate the effect of EAFAS on Compound 48/80-induced peritoneal mast cell degranulation and histamine release. When administration by the oral route—1?h before Compound 48/80 injection—EAFAS (at dose from 0.001–1?g/kg) completely inhibited the induced anaphylactic shock. EAFAS at concentrations ranging 0.25–1?mg/ml dose-dependently attenuated rates of mast cell degranulation and histamine release from RPMC that were evoked by Compound 48/80. The results of the present investigation indicated that EAFAS stabilizes the mast cell lipid bilayer membrane, thereby preventing the perturbation of membrane and the release of histamine. As a result of these anti-degranulating and anti-histaminic effects, it can be suggested that EAFAS may have a potential use in the prophylaxis and management of anaphylactic reactions.     

Release of Leukotrienes and Histamine by the Isolated Anaphylactic Heart

Abstract

The purpose of this study was to demonstrate the ability of heart tissue to release the mediators of anaphylaxis after antigenic challenges. Guinea pigs were sensitized with ovalbumin. Hearts were exised, perfused in a langendorff apparatus, and challenged with a bolus injection of ovalbumin. Analysis of the perfusates demonstrated the presence of histamine as determined by radioenzymatic assay. Histamine release was observed to be maximum after 2 min (8±1 nmol) of perfusion, then decreased to baseline level. The heart also released LTB₄, LTC₄, LTD₄, and LTE₄ as determined by high performance liquid chromatography and bioassays. The release of LTC₄ occurred rapidly, reaching maximum after 2 min (4.2±1 pmol) and then returned to baseline level. Although the release of LTD₄ paralleled the release of LTC₄, it reached a maximum after 5 min (7.7±2 pmol). LTE₄ was detected after 10 min and was undetectable after 15 min. Maximum release of LTB₄ was observed after 5-10 min (15±3 pmol) and was no longer detectable after 15 min. These results indicate that the isolated sensitized heart undergoing antigenic challenge releases leukotrienes and histamine suggesting the cardiac anaphylaxis might occur by the locally released mediators.