Mast Cell Products Research Articles

Perioperative Anaphylaxis and the United States Perspective

Perioperative Anaphylaxis and the United States Perspective

Catestatin, a neuroendocrine antimicrobial peptide, induces human mast cell migration, degranulation and production of cytokines and chemokines

Catestatin, a neuroendocrine antimicrobial peptide, induces human mast cell migration, degranulation and production of cytokines and chemokines

Epigallocatechin-3-gallate induces cytokine production in mast cells by stimulating an extracellular superoxide-mediated calcium influx

The green tea polyphenol (−)-epigallocatechin-3-O-gallate (EGCG) has various biological activities, including anti-inflammatory, anti-neoplastic, anti- and pro-apoptotic, and neuroprotective effects. Although these are often associated with increased intracellular reactive oxygen species (ROS) and Ca2+ levels, their involvement in biological effects is poorly understood. Here we report that EGCG induces cytokine production in mast cells via Ca2+ influx and ROS generation. EGCG at concentrations of ≥50μM induced interleukin-13 and tumor necrosis factor-α production in RBL-2H3 and bone marrow-derived mast cells. The effects were dependent on extracellular Ca2+, and EGCG induced Ca2+ release from intracellular stores and Ca2+ influx. Ca2+ influx was suppressed by 2-aminoethoxydiphenyl borate, an inhibitor of store-operated Ca2+ (SOC) channels, including Ca2+ release-activated Ca2+ channels and transient receptor potential canonical channels. EGCG failed to induce Ca2+ influx through SOC channels. EGCG-activated Ca2+ channels were genetically and pharmacologically distinct from Cav1.2 L-type Ca2+ channels, another route of Ca2+ influx into mast cells. EGCG evoked release of superoxide (O2−) into the extracellular space. Exogenous superoxide dismutase, but not catalase, inhibited EGCG-evoked Ca2+ influx and cytokine production, indicating that extracellular O2− regulates these events. EGCG can serve as a powerful tool for studying O2−-regulated Ca2+ channels, which may be selectively involved in the regulation of cytokine production but have yet to be elucidated.

Anti-inflammatory activity of 6-hydroxy-2,7-dimethoxy-1,4-henanthraquinone from tuberous roots of Yam (Dioscorea batatas) through inhibition of prostaglandin D2 and leukotriene C4 production in mouse bone marrow-derived mast cells

6-Hydroxy-2,7-dimethoxy-1,4-phenanthraquinone (PAQ) isolated from the tuberous roots of Yam (Dioscorea batatas) inhibited cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) dependent prostaglandin D(2) (PGD(2)) generation in mouse bone marrow-derived mast cells in a concentration-dependent manner with IC(50) values of 0.08 μM and 0.27 μM, respectively. In the Western blotting with specific anti-COX-2 antibodies, the decrease of the quantity of PGD(2) was accompanied by a decrease in the COX-2 protein level. But PAQ did not affect COX-1 protein level. In addition, this compound inhibited 5-lipoxygenase (5-LOX) dependent production of leukotriene C(4) in a dose-dependent manner, with an IC(50) of 0.032 μM. These results demonstrate that PAQ has a dual COX-2/5-LOX inhibitory activity. This compound also inhibited the degranulation reaction in a dose-dependent manner with an IC(50) of 2.7 μM. Thus, these results suggest that PAQ may be useful in regulating mast cell-mediated inflammatory diseases.

Analysis of Properties and Proinflammatory Functions of Cockroach Allergens Per a 1.01s

Cockroaches have been identified as one of the major indoor allergens inducing perennial rhinitis and asthma. Per a 1s are a group of the major allergens from American cockroach. Although Per a 1s are major allergens from American cockroach, factors contributing to the allergenicity of Per a 1s are still poorly defined. To investigate the effects of Per a 1s on the expression of PARs and the release of proinflammatory cytokines from mast cells. Per a 1.0101 and Per a 1.0104 were cloned from American cockroach and then expressed in Eschericia coli. The purified allergens were used to stimulate P815 mast cells, and the expression of protease-activated receptors (PARs) was determined by real-time RT-PCR and flow cytometry. The levels of IL-4 and IL-13 in culture media were detected with ELISA. Sera from 80 and 77.3% of cockroach allergy patients reacted to recombinant Per a (rPer a) 1.0101 and rPer a 1.0104, confirming they are major allergens. Both rPer a 1.0101 and rPer a 1.0104 had no enzymatic activity, but rPer a 1.0101 upregulated the expression of PAR-1 and PAR-2, and rPer a 1.0104 enhanced the expression of PAR-1 and PAR-4 proteins. Both recombinant allergens were able to increase the release of IL-4 and IL-13 from P815 mast cells. This is the first study aiming to investigate functions of group 1 allergens of American cockroach. rPer a 1.0101 and rPer a 1.0104 have the capacity to upregulate the expression of PARs and to enhance Th2 cytokine production in mast cells.

Kalanchoe pinnata inhibits mast cell activation and prevents allergic airway disease

Aqueous extract of Kalanchoe pinnata (Kp) have been found effective in models to reduce acute anaphylactic reactions. In the present study, we investigate the effect of Kp and the flavonoid quercetin (QE) and quercitrin (QI) on mast cell activation in vitro and in a model of allergic airway disease in vivo. Treatment with Kp and QE in vitro inhibited degranulation and cytokine production of bone marrow-derived mast cells following IgE/FcɛRI crosslinking, whereas treatment with QI had no effect. Similarly, in vivo treatment with Kp and QE decreased development of airway hyperresponsiveness, airway inflammation, goblet cell metaplasia and production of IL-5, IL-13 and TNF. In contrast, treatment with QI had no effect on these parameters. These findings demonstrate that treatment with Kp or QE is effective in treatment of allergic airway disease, providing new insights to the immunomodulatory functions of this plant.

Leukotriene B 4 receptor BLT-mediated phosphorylation of NF-κB and CREB is involved in IL-8 production in human mast cells induced by Trichomonas vaginalis-derived secretory products

Trichomonas vaginalis is a protozoan parasite that causes acute tissue inflammation in vaginal trichomoniasis. In this study, we investigated the signaling mechanisms through which T. vaginalis-derived secretory products (TvSP) induce chemokine IL-8 production in human mast cells. Stimulation with TvSP induced up-regulation of IL-8 protein secretion in HMC-1 cells. In addition, TvSP induced phosphorylation of transcription factors NF-κB and CREB in HMC-1 cells. Pretreatment of TvSP with lipase, but not heat or proteinase K strongly abolished the stimulatory effect on IL-8 production. Moreover, TvSP-induced IL-8 production and phosphorylation of NF-κB or CREB were inhibited when HMC-1 cells were stimulated with modified TvSP collected from 5-lipooxygenase inhibitor-treated trichomonads. Indeed, T. vaginalis-secreted lipid mediator LTB 4 (700 pg/ml) from 1 × 10 7 trichomonads. Furthermore, pretreatment of HMC-1 cells with antagonists for LTB 4 receptors BLT1 or BLT2 abolished the stimulatory effects of TvSP. Finally, TvSP-induced IL-8 production was inhibited by pretreatment with IκB or CREB inhibitors. These results suggest that T. vaginalis-derived secretory lipid mediator LTB 4 induces IL-8 production in mast cells via BLT-dependent activation of NF-κB and CREB.

Tryptase/Protease-Activated Receptor 2 Interactions Induce Selective Mitogen-Activated Protein Kinase Signaling and Collagen Synthesis by Cardiac Fibroblasts

The mast cell product, tryptase, has recently been implicated to mediate fibrosis in the hypertensive heart. Tryptase has been shown to mediate noncardiac fibroblast function via activation of protease-activated receptor 2 and subsequent activation of the mitogen-activated protein kinase pathway, including extracellular signal-regulated kinase 1/2. Therefore, we hypothesized that this pathway may be a mechanism leading to fibrosis in the hypertensive heart. Isolated adult cardiac fibroblasts were treated with tryptase, which induced activation of extracellular signal-regulated kinase 1/2 via protease-activated receptor 2. Blockade of protease activated receptor 2 with FSLLRY (10 μmol/L) and inhibition of the extracellular signal-regulated kinase pathway with PD98059 (10 μmol/L) prevented collagen synthesis in isolated cardiac fibroblasts stimulated with tryptase. In contrast, p38 mitogen-activated protein kinase and stress-activated protein/c-Jun N-terminal kinase were not activated by tryptase. Cardiac fibroblasts isolated from spontaneously hypertensive rats showed this same pattern of activation. Treatment of spontaneously hypertensive rats with FSLLRY prevented fibrosis in these animals, indicating the in vivo applicability of the cultured fibroblast findings. Also, tryptase induced a myofibroblastic phenotype indicated by elevations in α-smooth muscle actin and extra type III domain A (ED-A) fibronectin. Thus, the results from this study demonstrate the importance of tryptase for inducing a cardiac myofibroblastic phenotype, ultimately leading to the development of cardiac fibrosis. Specifically, tryptase causes cardiac fibroblasts to increase collagen synthesis via a mechanism involving activation of protease-activated receptor 2 and subsequent induction of extracellular signal-regulated kinase signaling.

Distinct Effects of Imperatorin on Allergic Rhinitis: Imperatorin Inhibits Caspase-1 Activity In Vivo and In Vitro

Because imperatorin (IPT), the furanocoumarins exhibits anti-inflammatory activity, we reasoned that IPT might modulate the allergic rhinitis (AR). The aim of this study was to analyze the regulation of AR by IPT. Here, we show the effect and mechanism of IPT in an ovalbumin (OVA)-induced AR model. The number of rubs after the OVA challenge in the OVA-sensitized mice was significantly higher than that in the OVA-unsensitized mice. The increased number of rubs was inhibited by the oral administration of IPT. The increased levels of IgE and histamine in the OVA-sensitized mice were reduced by IPT administration. The levels of interferon-γ were enhanced, whereas the levels of interleukin (IL)-4 were reduced on the spleen tissue of the IPT-administered AR mice. Protein levels of IL-1β, macrophage inflammatory protein-2, intercellular adhesion molecule-1, and cyclooxygenase-2 were reduced by IPT administration in the nasal mucosa of the OVA-sensitized mice. In the IPT-administered mice, the number of eosinophils and mast cells infiltration increased by OVA-sensitization were also decreased. In addition, IPT inhibited caspase-1 activity in the same nasal mucosa tissue. In activated human mast cells, the receptor-interacting protein 2 (RIP2), IκB kinase (IKK)-β, nuclear factor-κB (NF-κB)/RelA, and caspase-1 activation were increased, but increased RIP2, IKK-β, NF-κB/RelA, and caspase-1 activation were inhibited by the treatment of IPT. In addition, IPT inhibited caspase-1 activity and IL-1β production in IgE-stimulated bone marrow-derived mast cells. We can conclude that IPT exerts significant effects by regulating of caspase-1 activation in AR animal and in vitro models.

Sequential phosphorylation of SLP-76 at tyrosine 173 is required for activation of T and mast cells

Cooperatively assembled signalling complexes, nucleated by adaptor proteins, integrate information from surface receptors to determine cellular outcomes. In T and mast cells, antigen receptor signalling is nucleated by three adaptors: SLP-76, Gads and LAT. Three well-characterized SLP-76 tyrosine phosphorylation sites recruit key components, including a Tec-family tyrosine kinase, Itk. We identified a fourth, evolutionarily conserved SLP-76 phosphorylation site, Y173, which was phosphorylated upon T-cell receptor stimulation in primary murine and Jurkat T cells. Y173 was required for antigen receptor-induced phosphorylation of phospholipase C-γ1 (PLC-γ1) in both T and mast cells, and for consequent downstream events, including activation of the IL-2 promoter in T cells, and degranulation and IL-6 production in mast cells. In intact cells, Y173 phosphorylation depended on three, ZAP-70-targeted tyrosines at the N-terminus of SLP-76 that recruit and activate Itk, a kinase that selectively phosphorylated Y173 in vitro. These data suggest a sequential mechanism whereby ZAP-70-dependent priming of SLP-76 at three N-terminal sites triggers reciprocal regulatory interactions between Itk and SLP-76, which are ultimately required to couple active Itk to its substrate, PLC-γ1.

Solitary mastocytoma with histologic features of eosinophilic cellulites

ejd.2011.1317 Auteur(s) : Yue-Ping Zeng, Dong-Lai Ma mdonglai@sohu.com Department of Dermatology, Peking Union Medical College Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China Cutaneous mastocytoma is a localized variant of mastocytosis characterized by unusual excessive production and number of mast cells within the skin, without involvement of extracutaneous organs [1, 2]. Histologic features of eosinophilic cellulitis were rarely found [...]

Bronchoconstriction in nonhuman primates: a species comparison

Bronchoconstriction is a characteristic symptom of various chronic obstructive respiratory diseases such as chronic obstructive pulmonary disease and asthma. Precision-cut lung slices (PCLS) are a suitable ex vivo model to study physiological mechanisms of bronchoconstriction in different species. In the present study, we established an ex vivo model of bronchoconstriction in nonhuman primates (NHPs). PCLS prepared from common marmosets, cynomolgus macaques, rhesus macaques, and anubis baboons were stimulated with increasing concentrations of representative bronchoconstrictors: methacholine, histamine, serotonin, leukotriene D₄ (LTD₄), U46619, and endothelin-1. Alterations in the airway caliber were measured and compared with previously published data from rodents, guinea pigs, and humans. Methacholine induced maximal airway constriction, varying between 74 and 88% in all NHP species, whereas serotonin was ineffective. Histamine induced maximal bronchoconstriction of 77 to 90% in rhesus macaques, cynomolgus macaques, and baboons and a lesser constriction of 53% in marmosets. LTD₄ was ineffective in marmosets and rhesus macaques but induced a maximum constriction of 44 to 49% in cynomolgus macaques and baboons. U46619 and endothelin-1 caused airway constriction in all NHP species, with maximum constrictions of 65 to 91% and 70 to 81%, respectively. In conclusion, PCLS from NHPs represent a valuable ex vivo model for studying bronchoconstriction. All NHPs respond to mediators relevant to human airway disorders such as methacholine, histamine, U46619, and endothelin-1 and are insensitive to the rodent mast cell product serotonin. Only PCLS from cynomolgus macaques and baboons, however, responded also to leukotrienes, suggesting that among all compared species, these two NHPs resemble the human airway mechanisms best.

Histamine H4 receptor activation enhances LPS‐induced IL‐6 production in mast cells via ERK and PI3K activation

The histamine H(4) receptor (H(4)R) has been implicated in numerous inflammatory functions. Here it is shown that the receptor can mediate cytokine production from mast cells. Histamine and an H(4)R agonist, JNJ 28610244, induced the production of IL-6 in mouse bone marrow (BM)-derived mast cells. This effect was blocked by two different H(4)R antagonists and was not present in H(4)R-deficient cells. In addition, histamine acting via the H(4) R potentiated LPS-induced IL-6 production. Histamine-induced IL-6 production could be blocked by inhibitors of ERK and phosphoinositide 3-kinase γ (PI3Kγ) pathways. Furthermore, it was shown that H(4)R activation can induce phosphorylation of ERK, MEK and AKT. H(4)R activation led to a rapid and transient phosphorylation of these kinases, whereas with LPS the activation occurred at later time points. When both histamine and LPS were added, the phosphorylation was evident at 5 min and persisted for at least 60 min suggesting that changes in the kinetics of kinase activation may be one mechanism driving the signaling interaction between the H(4)R and toll-like receptors. These observations suggest that the H(4)R can synergize with other inflammatory signals to potentiate cytokine production and provides mechanistic information on the role of the H(4)R in inflammation.

Regulatory T cells enhance mast cell production of IL6 via a TGFβ dependent innate mechanism (168.20)

Abstract Recently, Tregs have been proposed to limit mast cell degranulation upon antigen stimulation. However, mast cells also produce many cytokines that regulate both innate and adaptive immunity. Here we show that Tregs inhibit mast cell (BMMC) degranulation but, surprisingly, promotes IL6 in response to innate (LPS or PGN) and adaptive (IgE) activation. This required cell-cell contact and did not require activation via the TCR. Blockade of OX40/OX40L pathway inhibited the Treg effects on BMMC degranulation but had no effect on IL6 production. Conversely, blockade of surface bound-TGFβ ablated IL6 production, suggesting that Tregs influence mast cell responses via distinct mechanisms. Furthermore, TGFβ was sufficient to promote enhanced IL6 but had no effect on degranulation. In innate immunity, IL6 and Tregs have been suggested to influence neutrophil clearance and resolution of inflammation. In an LPS-driven model of lung injury, Treg depletion elevated lung neutrophilia in response to LPS. Similarly, mast cell deficient mice displayed significantly elevated neutrophilia in the lung that was fully corrected upon reconstitution with wildtype mast cells but not by IL6 deficient mast cells, suggesting a critical role for mast cell derived IL-6 in neutrophil clearance during innate inflammation. Our data suggests that Tregs are important in limiting the severity of the inflammatory response during innate activation and that they may do so by promoting mast cell production of IL-6.

S100A8 Modulates Mast Cell Function and Suppresses Eosinophil Migration in Acute Asthma

S100A8 is implicated in the pathogenesis of inflammatory diseases. S100A8 is upregulated in macrophages by Toll-like receptors (TLR)-3, 4, and 9 agonists in an IL-10-dependent manner, and by corticosteroids in vitro and in vivo, and scavenges oxidants generated by activated phagocytes. Because if its elevated expression in various lung disorders, we asked whether S100A8 was protective in allergic inflammation. S100A8, but not Cys(41)-Ala S100A8, in which the single reactive Cys residue was replaced by Ala, reduced mast cell (MC) degranulation and production of particular cytokines (IL-6, IL-4, and granulocyte macrophage colony-stimulating factor) in response to IgE-crosslinking in vitro, likely by inhibiting intracellular reactive oxygen species production, thereby reducing downstream linker for activation of T cells and extracellular signal regulated kinase/mitogen-activated protein kinase phosphorylation. In lungs of mice with acute asthma, S100A8, but not Cys(41)-Ala S100A8, reduced MC degranulation, production of eosinophil chemoattractants (IL-5, eotaxin, and monocyte chemoattractant protein-1), and eosinophil infiltration. Suppression of IL-6 and IL-13 could have contributed to reduced mucus production seen in lungs of S100A8-treated mice. IgE production was unaffected. In asthma, there is an imbalance of anti-oxidant systems that are generally protective. Our results strongly support a protective role for S100A8 in allergic inflammation by modulating MC activation and eosinophil recruitment, and by scavenging oxidants generated by activated leukocytes, in processes reliant on its thiol-scavenging capacity.

A New Naphthoquinone Isolated from the Bulbs ofCipura paludosaand Pharmacological Activity of Two Main Constituents

Cipura paludosa (Iridaceae) is a plant that is distributed in the north region of Brazil. Its bulbs are used in folk medicine to treat inflammation and pain. Four naphthalene derivatives have been isolated from the bulbs of this plant. Three of them have been identified as the known naphthalene derivatives, eleutherine, iso-eleutherine, and hongkonin. The structure of the fourth and new component was determined as 11-hydroxyeleutherine by extensive NMR study. In addition, the IN VIVO effect of the two major compounds, eleutherine and iso-eleutherine, was evaluated in carrageenan-induced hypernociception and inflammation in mice. Eleutherine and iso-eleutherine (1.04-34.92 µmol/kg), dosed intraperitoneally (i.p.) or orally (p.o.), decreased the carrageenan-induced paw oedema (i.p. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively; p.o. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively). Iso-eleutherine, but not eleutherine, significantly reduced (inhibitions of 39 ± 4 %) the plasma extravasation induced by intradermal (i.d.) injection of carrageenan. Likewise, eleutherine and iso-eleutherine (1.04-34.92 µmol/kg, i.p. or p.o.) were also effective in preventing the carrageenan-induced hypernociceptive response (i.p. - inhibition of 59 ± 4 % and 63 ± 1 %, respectively; p.o. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively). It was also suggested that the anti-inflammatory and anti-hypernociceptive effects of eleutherine or iso-eleutherine partly depend on the interference with the synthesis or activity of mast cell products, kinins, cytokine, chemokines, prostanoids, or sympathetic amines. Our findings show that two major compounds of C. paludosa contain pharmacologically active constituents that possess antinociceptive and anti-inflammatory activity, justifying, at least in part, its popular therapeutic use for treating conditions associated with pain.

Activation of the PI3K pathway increases TLR-induced TNF-α and IL-6 but reduces IL-1β production in mast cells

Recognition of bacterial constituents by mast cells (MCs) is dependent on the presence of pattern recognition receptors, such as Toll-like receptors (TLRs). The final cellular response, however, depends on the influence of multiple environmental factors. In the current study we tested the hypothesis that the PI3K-activating ligands insulin-like growth factor-1 (IGF-1), insulin, antigen, and Steel Factor (SF) are able to modulate the TLR4-mediated production of proinflammatory cytokines in murine MCs. Costimulation with any of these ligands caused increased LPS-triggered secretion of IL-6 and TNF-α, but attenuated the production of IL-1β, though all three cytokines were produced in an NFκB-dependent manner. The pan-specific PI3K-inhibitor Wortmannin reverted the altered production of these cytokines. In agreement, MCs deficient for SHIP1, a negative regulator of the PI3K pathway, showed augmented secretion of IL-6/TNF-α and reduced production of IL-1β in response to LPS alone. The differential effects of IGF-1 on TLR4-mediated cytokine production were also observed in the context of TLR2 and IL-33 receptor-mediated MC activation. Importantly, these effects were seen in both bone marrow-derived and peritoneal MCs, suggesting general relevance for MCs. Using pharmacological and genetic tools, we could show that the p110δ isoform of PI3K is strongly implicated in SF-triggered suppression of LPS-induced IL-1β production. Costimulation with antigen was affected to a lesser extent. In conclusion, NFκB-dependent production of proinflammatory cytokines in MCs is differentially controlled by PI3K-activating ligand/receptor systems.

Immunomodulatory properties of a lemon-quince preparation (Gencydo®) as an indicator of anti-allergic potency

Gencydo®, a combination of lemon (Citrus limon) juice and aqueous quince (Cydonia oblonga) extract has been used traditionally in anthroposophical medicine for treating patients with allergic rhinitis or asthma. Because there are no reports about the mode of action, we investigated the anti-allergic effects of this preparation in vitro by using cell lines and primary cells in various biological and immunological endpoints. The release of soluble mediators from basophilic cells, mast cells and lung epithelial cells, which are essential for the initiation of early- and late-phase allergic reactions, was analyzed in relation to the synthetic anti-allergic drugs azelastine and dexamethasone. In addition, the impact of Gencydo® on the viability and activation of GM-CSF-activated eosinophil granulocytes was investigated. Gencydo® reduced the degranulation and histamine release of IgE-activated basophilic cells and mast cells and inhibited the IgE- and PMA/A23187-induced increases in IL-8, TNF-α and GM-CSF production in mast cells. The effects were comparable to that of the used concentration of azelastine and dexamethasone. Furthermore, Gencydo® partially blocked eotaxin release from human bronchial epithelial cells, but has no impact on the viability and activation of GM-CSF-activated eosinophil granulocytes. In conclusion, these results give a rational base for the topical use of Gencydo® in treatment of allergic disorders through the down regulation of soluble mediators, which are essential for the initiation and maintenance of allergic reactions.

Catestatin, a neuroendocrine antimicrobial peptide, induces human mast cell migration, degranulation and production of cytokines and chemokines

Catestatin, a neuroendocrine peptide with effects on human autonomic function, has recently been found to be a cutaneous antimicrobial peptide. Human catestatin exhibits three single nucleotide polymorphisms: Gly364Ser, Pro370Leu and Arg374Gln. Given reports indicating that antimicrobial peptides and neuropeptides induce mast cell activation, we postulated that catestatin might stimulate numerous functions of human mast cells, thereby participating in the regulation of skin inflammatory responses. Catestatin and its naturally occurring variants caused the human mast cell line LAD2 and peripheral blood-derived mast cells to migrate, degranulate and release leukotriene C(4) and prostaglandins D(2) and E(2). Moreover, catestatins increased intracellular Ca(2+) mobilization in mast cells, and induced the production of pro-inflammatory cytokines/chemokines such as granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein-1/CCL2, macrophage inflammatory protein-1α/CCL3 and macrophage inflammatory protein-1β/CCL4. Our evaluation of possible cellular mechanisms suggested that G-proteins, phospholipase C and the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) are involved in catestatin-induced mast cell activation as evidenced by the inhibitory effects of pertussis toxin (G-protein inhibitor), U-73122 (phospholipase C inhibitor) and U0126 (ERK inhibitor), respectively. We also found that human mast cells express the α7 subunit of the nicotinic acetylcholine receptor at both the mRNA and protein levels. Given that silencing the α7 receptor mRNA and an α7-specific inhibitor did not affect catestatin-mediated activation of mast cells, however, we concluded that this receptor is not likely to be functional in human mast cell stimulation by catestatins. Our finding that the neuroendocrine antimicrobial peptide catestatin activates human mast cells suggests that this peptide might have immunomodulatory functions, and provides a new link between neuroendocrine and cutaneous immune systems.

Luteolin-7-O-glucoside Suppresses Leukotriene C4 Production and Degranulation by Inhibiting the Phosphorylation of Mitogen Activated Protein Kinases and Phospholipase C.GAMMA.1 in Activated Mouse Bone Marrow-Derived Mast Cells

In this study, luteolin-7-O-glucoside (L7G), an herbal medicine isolated from Ailanthus altissima, inhibited 5-lipoxygenase (5-LOX)-dependent leukotriene C(4) (LTC(4)) production in bone marrow-derived mast cells (BMMCs) in a concentration-dependent manner with an IC(50) of 3.0 µM. To determine the action mechanism of L7G, we performed immunoblotting for cytosolic phospholipase A(2) (cPLA(2)) and mitogen-activated protein kinases (MAPKs) following c-kit ligand (KL)-induced activation of BMMCs with or without L7G. Inhibition of LTC(4) production by L7G was accompanied by a decrease in cPLA(2) phosphorylation, which occurred via the extracellular signal-regulated protein kinase-1/2 (ERK1/2) and p38 and c-Jun N-terminal kinase (JNK) pathways. In addition, L7G also attenuated mast cell degranulation in a dose-dependent manner (IC(50), 22.8 µM) through inhibition of phospholipase Cγ1 (PLCγ1) phosphorylation. Our results suggest that the anti-asthmatic activity of L7G may be mediated in part via the inhibition of LTC(4) generation and mast cell degranulation.