Mrgprb2 gene plays a role in the anaphylactoid reactions induced by Houttuynia cordata injection

ETHNOPHARMACOLOGICAL RELEVANCE

Houttuynia cordata Thunb., a plant belonging to the family of Saururaceae, has been used as a traditional Chinese medicine for more than 1500 years. Because of its various pharmacological activities, it was widely used as antipyretic, detoxification, anti-inflammatory drugs. Houttuynia cordata (HC) injection was prepared using contemporary methods to extract effective components from H. cordata Thunb. However, the adverse event reports of HC injection are accumulating remarkably with the HC injection clinical applications increased. Previous studies demonstrated that the major side effects of HC injection were anaphylactoid reactions. Our work might shed the light on the role of Mas-related G-protein coupled receptor-X2 (MRGPRX2) in modulating drug-induced anaphylactoid reactions.

AIM OF THE STUDY

We aimed to investigate the role of the mouse Mas-related G-protein coupled receptor B2 (Mrgprb2) (the orthologous gene of human MRGPRX2) in anaphylactoid reactions induced by HC injection.

MATERIALS AND METHODS

Mrgprb2 related anaphylactoid reactions induced by HC injection were investigated by histamine/β-hexosaminidase releasing, mast cell degranulation, and hind paw swelling assays by using a Mrgprb2 knockout mouse model. Furthermore, the transcriptomic profiles of the anaphylactoid reaction induced by HC injection was analyzed by RNA sequencing.

RESULTS

Mice without Mrgprb2 exhibited significantly decreasing in mast cell degranulation, serum histamine release, and hind paw swelling degrees. The RNA sequencing results indicated that Mrgprb2 could play a pivotal role in HC injection induced anaphylactoid reaction mediated by mTOR/AMPK pathway. Intriguingly, our results showed that Mrgprb2 might involve in Compound 48/80 induced anaphylactoid reactions mediated by Reelin/E-cadherin axis, which suggested different roles of Mrgprb2 in anaphylactoid reactions induced by HC injection and C48/80.

CONCLUSION

Our studies reported effects and underlying mechanisms of Mrgprb2 in the anaphylactoid reaction induced by HC injection.

α-Linolenic acid attenuates pseudo-allergic reactions by inhibiting Lyn kinase activity

BACKGROUND

Pseudo-allergic reactions are potentially fatal hypersensitivity responses caused by mast cell activation. α-linolenic acid (ALA) is known for its anti-allergic properties. However, its potential anti-pseudo-allergic effects were not much investigated.

PURPOSE

To investigate the inhibitory effects of ALA on IgE-independent allergy in vitro, and in vivo, as well as the mechanism underlying its effects.

METHODS/STUDY DESIGNS

The anti-anaphylactoid activity of ALA was evaluated in passive cutaneous anaphylaxis reaction (PCA) and systemic anaphylaxis models. Calcium imaging was used to assess intracellular Ca2+ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway.

RESULTS

ALA (0, 1.0, 2.0, and 4.0 mg/kg) dose-dependently reduced serum histamine, chemokine release, vasodilation, eosinophil infiltration, and the percentage of degranulated mast cells in C57BL/6 mice. In addition, ALA (0, 50, 100, and 200 μM) reduced Compound 48/80 (C48/80) (30 μg/ml)-or Substance P (SP) (4 μg/ml)-induced calcium influx, mast cell degranulation and cytokines and chemokine release in Laboratory of Allergic Disease 2 (LAD2) cells via Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway. Moreover, ALA (0, 50, 100, and 200 μM) inhibited C48/80 (30 μg/ml)- and SP (4 μg/ml)-induced calcium influx in Mas-related G-protein coupled receptor member X2 (MrgX2)-HEK293 cells and in vitro kinase assays confirmed that ALA inhibited the activity of Lyn kinase. In response to 200 μM of ALA, the activity of Lyn kinase by (7.296 ± 0.03751) × 10-5 units/μl and decreased compared with C48/80 (30 μg/ml) by (8.572 ± 0.1365) ×10-5 units/μl.

CONCLUSION

Our results demonstrate that ALA might be a potential Lyn kinase inhibitor, which could be used to treat pseudo-allergic reaction-related diseases such as urticaria.

Oleanolic acid protects against mast cell-mediated allergic responses by suppressing Akt/NF-κB and STAT1 activation

BACKGROUND

Oleanolic acid (OA) is an active compound found in a variety of medicinal herbs and plants. Though OA has been widely attributed with a variety of biological activities, studies focused on its anti-allergic inflammation properties are insufficient.

PURPOSE

Given the rapid increase in allergic diseases and the lack of fundamental treatment options, this study aimed to find a safe and effective therapy for allergic disorders.

METHODS

We evaluated the inhibitory effect of OA on allergic inflammatory response and the possible mechanisms underlying the effect using phorbol-12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated human mast cell (HMC)-1, and a mouse model of compound 48/80-induced anaphylactic shock.

RESULTS

OA suppressed pro-inflammatory cytokine expressions in PMACI-induced HMC-1 cells by inhibiting activation of the Akt, p38 mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), and signal transducer and activator of transcription (STAT) 1 signaling pathways. Moreover, OA showed a protective effect against compound 48/80-induced anaphylactic shock through inhibition of histamine release and immunoglobulin E level via regulation of NF-κB and STAT1 activation.

CONCLUSION

The results showed that OA suppressed mast cell-mediated allergic response by transcriptional regulation. We suggest that OA has potential effect against allergic inflammatory disorders, including anaphylaxis, and might be a useful therapeutic agent for allergic disease.

Inhibitory function of Shikonin on MRGPRX2-mediated pseudo-allergic reactions induced by the secretagogue

BACKGROUND

Mast cells (MCs) are crucial effectors in allergic disorders by secreting inflammatory mediators. The Mas-related G-protein-coupled receptor X2 (Mrgprx2) was shown to have a key role in IgE-independent allergic reactions. Therefore, potential drug candidates that directly target Mrgprx2 could be used to treat pseudo-allergic diseases. Shikonin, an active ingredient derived from Lithospermum erythrorhizon Sieb. et Zucc has been used for its anti-inflammatory properties since ancient China.

PURPOSE

To investigate the inhibitory effects of Shikonin on IgE-independent allergy both in vitro and in vivo, as well as the mechanism underlying its effects.

METHODS/STUDY DESIGNS

The anti-anaphylactoid activity of Shikonin was evaluated in PCA and systemic anaphylaxis models, Calcium imaging was used to assess intracellular Ca²⁺ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of PLCγ-PKC-IP3 signaling pathway. The analytical method of surface plasmon resonance was employed to study the interaction between Shikonin and potential target protein Mrgprx2.

RESULTS

Shikonin can suppress compound 48/80 (C48/80)-induced PCA, active systemic anaphylaxis, and MCs degranulation in mice in a dose-dependent manner. In addition, Shikonin reduced C48/80-induced calcium flux and suppressed LAD2 cell degranulation via PLCγ-PKC-IP3 signaling pathway. Moreover, Shikonin was found to inhibit C48/80-induced Mrgprx2 expression in HEK cells, displaying specific interactions with the Mrgprx2 protein.

CONCLUSION

Shikonin could be a potential antagonist of Mrgprx2, thereby inhibiting pseudo-allergic reactions through Ca²⁺ mobilization.

Protective Effect of Genistein against Compound 48/80 Induced Anaphylactoid Shock via Inhibiting MAS Related G Protein-Coupled Receptor X2 (MRGPRX2)

Anaphylactoid shock is a fatal hypersensitivity response caused by non-IgE mediated mast cell activation. These reactions are mediated by a family of G protein-coupled receptors (GPCRs) known as Mas related GPCRX2 (MRGPRX2). Several US FDA approved drugs which are used in day to day life have been reported to cause anaphylactoid shock. Surprisingly, no therapeutic drugs are available which can directly target MRGPRX2 for treatment of anaphylactoid shock. Genistein is a non-steroidal polyphenol known for its diverse physiological and pharmacological activities. In recent studies, Genistein has been reported for its anti-inflammatory activity on mast cells. However, the effects and mechanistic pathways of Genistein on anaphylactoid reaction remain unknown. In the present study, we designed a battery of in-vitro, in-silico and in-vivo experiments to evaluate the anti-anaphylactoid activity of Genistein in order to understand the possible molecular mechanisms of its action. The in-vitro results demonstrated the inhibitory activity of Genistein on MRGPRX2 activation. Further, a mouse model of anaphylactoid shock was used to evaluate the inhibitory activity of Genistein on blood vessel leakage and hind paw edema. Taken together, our findings have demonstrated a therapeutic potential of Genistein as a lead compound in the treatment of anaphylactoid shock via MRGPRX2.

Eupatilin suppresses the allergic inflammatory response in vitro and in vivo

INTRODUCTION

Eupatilin, a pharmacologically active ingredient found in Artemisia asiatica, has been reported to have anti-oxidative, anti-inflammatory, and anti-apoptotic activities. However, molecular mechanisms underlying its anti-allergic properties are not yet clear. In this study, we investigated the effects of eupatilin on allergic inflammation in phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated human mast cells and a compound 48/80-induced anaphylactic shock model.

METHODS

Cytokine assays, histamine assays, quantitative real-time polymerase chain reaction analysis, western blot analysis and compound 48/80-induced anaphylactic shock model were used in this study.

RESULTS

Eupatilin significantly suppresses the expression and production of pro-inflammatory cytokines, such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 in vitro and in vivo. In addition, eupatilin inhibits nuclear factor kappa B (NF-κB) activation by regulating the phosphorylation and degradation of IκBα via the Akt/IKK(α/β) pathway. Eupatilin treatment also attenuates the phosphorylation of p38, ERK, and JNK MAPKs. Furthermore, eupatilin blocked anaphylactic shock and decreased the release of histamine.

CONCLUSIONS

Anti-allergic inflammation may involve the expression and production of regulating pro-inflammatory cytokines via Akt/IKK(α/β) and MAPK activation of NF-κB. On the basis of these data, eupatilin is a potential candidate for the treatment of allergic diseases.

TNF-α/TNFR1 Signaling is Required for the Full Expression of Acute and Chronic Itch in Mice via Peripheral and Central Mechanisms

Increasing evidence suggests that cytokines and chemokines play crucial roles in chronic itch. In the present study, we evaluated the roles of tumor necrosis factor-alpha (TNF-α) and its receptors TNF receptor subtype-1 (TNFR1) and TNFR2 in acute and chronic itch in mice. Compared to wild-type (WT) mice, TNFR1-knockout (TNFR1-KO) and TNFR1/R2 double-KO (DKO), but not TNFR2-KO mice, exhibited reduced acute itch induced by compound 48/80 and chloroquine (CQ). Application of the TNF-synthesis inhibitor thalidomide and the TNF-α antagonist etanercept dose-dependently suppressed acute itch. Intradermal injection of TNF-α was not sufficient to evoke scratching, but potentiated itch induced by compound 48/80, but not CQ. In addition, compound 48/80 induced TNF-α mRNA expression in the skin, while CQ induced its expression in the dorsal root ganglia (DRG) and spinal cord. Furthermore, chronic itch induced by dry skin was reduced by administration of thalidomide and etanercept and in TNFR1/R2 DKO mice. Dry skin induced TNF-α expression in the skin, DRG, and spinal cord and TNFR1 expression only in the spinal cord. Thus, our findings suggest that TNF-α/TNFR1 signaling is required for the full expression of acute and chronic itch via peripheral and central mechanisms, and targeting TNFR1 may be beneficial for chronic itch treatment.

The false-positive responses of analgesic drugs to the intradermal serotonin- and compound 48/80-induced scratches as an animal model of itch

Intradermal injection of pruritogens such as serotonin, histamine and compound 48/80 into the skin and then, the evaluation of the scratching behavior is the commonly used animal model to advance pruritic research and drug development. However, predictive validity of this model is poorly documented. There is a close interaction between itch and pain sensations with regard to mediation through an anatomically and functionally identical neuronal pathway. One approach is whether the existing animal model of itch differentiates itch or pain to show efficacy of clinically effective analgesic drugs as a back translation. In this study, we explored the effects of different group of analgesic drugs on serotonin and compound 48/80-induced scratching behavior in Balb-C mice. Serotonin (25 μg) and compound 48/80 (100 μg) was injected intradermally in a volume of 50 μl into the rostral part of skin on the back of male mice and scratches were counted for a 30-min observation period. Morphine (1, 3, 10 mg/kg), tramadol (20, 40, 80 mg/kg), cannabinoid agonist CP 55,940 (0.1, 0.3, 1 mg/kg), paracetamol (100, 200, 300 mg/kg) and diclofenac (50, 100, 200 mg/kg) were given intraperitoneally 30 min prior to pruritogen injection. The analgesic drugs dose dependently blocked serotonin and compound 48/80-induced straching behavior with exerting complete inhibition at certain doses. Our data suggests that intradermal pruritogen-induced scratching models may not discriminate pain and itch sensations and give false positive results when standard analgesic drugs are used.

Novel phenotype in beagle dogs characterized by skin response to compound 48/80 focusing on skin mast cell degranulation

Beagle dogs have long been employed in toxicology studies and as skin disease models. Compared with other experimental animal species, they are known to be susceptible to skin responses, such as rashes, from exposure to various chemical compounds. Here, a unique dog phenotype was identified that showed no skin response to compound 48/80, a mast cell degranulating agent. Although the skin responses to intradermal injection of polyoxyethylene castor oil derivative (HCO-60, a nonionic detergent), histamine dihydrochloride, concanavalin A (IgE receptor-mediated stimuli), or calcium ionophore A23187 were comparable in wild-type (WT) dogs and these nonresponder (NR) dogs, only the response to compound 48/80 was entirely absent from NR dogs. The skin mast cell density and histamine content per mast cell were histologically comparable between WT and NR dogs. By checking for skin responses to compound 48/80, NR dogs were found to exist at the proportion of 17-20% among four animal breeders. From retrospective analysis of in-house breeding histories, the NR phenotype appears to conform to the Mendelian pattern of recessive inheritance. The standard skin response in WT dogs developed at 2-4 months of age. In conclusion, this unique phenotype, typified by insensitivity in the compound 48/80-induced degranulation pathway in mast cells, has been widely retained by recessive inheritance in beagle dogs among general experimental animal breeders. The knowledge concerning this phenotype could lead to better utilization of dogs in studies and aid in model development.

Antiallergic activity of Aristolochia bracteolata Lank in animal model

Antiallergic activity of Aristolochia bracteolata was evaluated by using compound 48/80 induced anaphylaxis, dermatitis rhinitis and pruritus, as a preclinical model for acute phase of hypersensitivity reactions. The late phase hypersensitivity was evidenced by considering toluidine diisocyanate induced volume of bronchoalveolar fluid secretion and its inhibition. The possible antiallergic mechanism was evaluated by using compound 48/80 induced mast cell activation and estimated serum nitric oxide (NO), rat peritoneal fluid NO, bronchoalveolar fluid NO and blood histamine levels. The present study implied that the chloroform extract of Aristolochia bracteolata had potent and significant inhibitory effect on compound 48/80 induced pruritus and dermatitis activity in Swiss albino mice. It showed significant effect in toluidine diisocyanate induced rhinitis in swiss albino mice. Mast cell membrane stabilization activity was also observed in compound 48/80 induced mast cell activation. A significant reduction was observed in serum nitrate levels, rat peritoneal fluid nitrate levels and BAL nitrate levels. The extract was also found to possess significant inhibitory effect on blood histamine levels. It could be concluded that chloroform extract of A. bracteata possess potent antiallergic activity, possibly through mast cell membrane stabilization, inhibiting NO and histamine pathway.

Repeated recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80, a mast cell degranulator

We examined the recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80 (C48/80), a mast cell degranulator. During the period of 0.5 h to 24 h after treatment with C 48/80 (0.75 mg/kg, i.p.), an apparent recurrence of gastric mucosal lesions was found 18 and 24 h after the lesion formation, progression, and recovery occurred during the period of 12 h. Gastric mucosal blood flow showed the maximum reduction at 0.5, 16, and 22 h after treatment followed by the maximum recovery of the decrease at 12, 20, and 24 h, respectively. Gastric mucosal myeloperoxide and xanthine oxidase activities and lipid peroxide content showed the maximum increase at 3, 18, and 24 h after treatment. Gastric mucosal superoxide dismutase activity unchanged after treatment and gastric mucosal catalase activity decreased only at 24 h. Gastric mucosal Se-glutathione peroxidase activity and vitamin E, ascorbic acid, and hexosamine contents showed their maximum decrease at 3, 18, and 24 h after treatment. Gastric mucosal non-protein SH content showed the maximum decrease at 0.5, 16, and 22 h after treatment. Serum histamine and serotonin concentrations increased rapidly after treatment but the increases in serum histamine and serotonin concentrations diminished completely until 12 and 14 h, respectively. These results indicate that lesions recur repeatedly accompanied with an ischemia-reperfusion-like change in blood flow, inflammation, and disruption of antioxidant defense systems in the gastric mucosa of rats in no relation to released histamine and serotonin after a single C48/80 treatment.

Time course of human conjunctival mast cell degranulation in response to compound 48/80

Compound 48/80, a non-immunogenic mast cell degranulatory agent, is known to produce the signs and symptoms of ocular allergy. Maximal mast cell degranulation of human conjunctiva occurred within the first hour after stimulation by a single topical dose of compound 48/80 (20 microliters, 7.5 mg/ml). The average percentage of fully degranulated mast cells in treated specimens (n = 9) was 31% (range 5-60%) versus 6% (range 0-20%) in control specimens (n = 5). Exact correlates of representative granulated, partially degranulated, and fully degranulated mast cells were determined by light and transmission electron microscopy.

Ocular anaphylaxis induced in the rat by topical application of compound 48/80. Dose response and time course study

In the present study we sought to develop a model of ocular anaphylaxis based on the topical application of compound 48/80 to the surface of the rat eye. Doses ranging from 50 to 1000 micrograms were found to produce graded edema of the conjunctiva and swelling of the lid. On histologic examination, 50 microns compound 48/80 produced no changes distinguishable from those in PBS-treated controls, 150 microns produced mild alterations, and 250, 500, and 1000 micrograms compound 48/80 produced a marked increase in degranulated mast cells and a mild influx of neutrophils. The time course of the response to 250 micrograms and 1000 micrograms of compound 48/80 was evaluated over a 72-h period. Both doses elicited epithelial damage. A mild reduction in the number of mast cell was seen at 6 h in rats receiving 250 or 1000 micrograms. The reduction persisted to 72 h in rats receiving 1000 micrograms. The number of neutrophils was increased at 1 and 6 h in eyes treated with 250 micrograms and at 1, 6, and 24 h in eyes treated with 1000 micrograms compound 48/80. The clinical and histologic changes induced by application of 250 micrograms compound 48/80 resemble those seen in patients with allergic conjunctivitis suggesting that a model of ocular anaphylaxis based on the topical application compound 48/80 will be clinically relevant and experimentally practical.

Meliae cortex extract exhibits anti-allergic activity through the inhibition of Syk kinase in mast cells

The anti-allergic action of various Oriental medicinal herbs was investigated using in vitro and in vivo experimental models. Of these extracts, the ethanol extract of Meliae cortex (MC) exhibited the most potent activity in mast cells; its IC(50) values were 29+/-1.5 microg/ml for antigen stimulation and 57+/-3.4 microg/ml for thapsigargin stimulation. It inhibited compound-48/80-induced systemic anaphylaxis by 52.9% at a dose of 300 mg/kg in mice; it also inhibited the expression of the proinflammatory mediator TNF-alpha. With regard to its mechanism of action, MC suppressed the activating phosphorylation of Syk, a key enzyme in mast-cell signaling processes and that of Akt in a dose-dependent manner. It also inhibited the MAP kinase ERK1/2, which is critical for the production of inflammatory cytokines in mast cells, as indicated by the suppression of the activating phosphorylation of ERK1/2. Taken together, these results suggest that the anti-allergic activity of MC may be due to the inhibition of histamine secretion and cytokine expression through the Syk inhibition in mast cells.

Artemisia iwayomogi inhibits immediate-type allergic reaction and inflammatory cytokine secretion

The immediate-type allergic reaction is involved in many allergic diseases such as asthma and allergic rhinitis. The discovery of drugs for the treatment of immediate-type allergic diseases is a very important subject in human health. In this study, we investigated the effect of Artemisia iwayomogi (AIAE) on mast cell-mediated allergic reaction and inflammatory cytokine secretion. AIAE inhibited compound 48/80-induced systemic reactions in mice. AIAE decreased the passive cutaneous anaphylaxis (PCA) reaction activated by antidinitrophenyl (anti-DNP) IgE antibody. AIAE dose-dependently reduced histamine release from rat peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. Furthermore, AIAE attenuated the phorbol 12-myristate 13-acetate plus calcium ionophore A23187-stimulated tumor necrosis factor-alpha and interleukin-6 secretion in human mast cells. These results provide evidence that AIAE may be beneficial in the treatment of allergic diseases.

Gamijeonssibaekchulsan regulates mast cell-mediated anaphylactic reaction

Gamijeonssibaekchulsan (GJBS) is a typical Oriental medicine prescription which has been used in Korea for the treatment of allergic diseases and the development of physical strength. However, as yet there is no clear explanation of how GJBS affects the anaphylactic reaction and the immune function. In the present study murine models and MOLT-4 cells, a T cell line, were used to investigate these effects. Compound 48/80-induced systemic anaphylactic shock and ear swelling response were firstly analyzed. We also assayed histamine release and passive cutaneous anaphylaxis (PCA) in mice and cytokine productions in MOLT-4 cells. GJBS significantly inhibits compound 48/80-induced systemic anaphylactic shock and ear swelling response. GJBS also inhibits histamine release from rat peritoneal mast cells induced by compound 48/80. PCA activated by anti-dinitrophenyl immunoglobulin E is attenuated by GJBS. However, GJBS dose not affect the production of interferon-gamma, interleukin (IL)-2, and IL-4 in MOLT-4 cells. These results indicate that GJBS has a potential regulatory effect on allergic reactions that are mediated by mast cells.

Characteristics of scratching behavior induced by some chemical mediators in hairless mice

To find the characteristics of scratching behavior in hairless mice (HR-1), compound 48/80 and some putative chemical mediators of allergic reaction were injected intradermally into the backs of mice, and the number of scratching behaviors was measured. As reference mice, NC/Nga, ICR, and ddY mice were used. Scratching behavior in HR-1 and ICR mice was increased dose-dependently by compound 48/80. The same result was also observed with NC/Nga and ddY mice. However, the response in NC/Nga and ddY mice was far less than those of HR-1 and ICR mice. Similar to NC/Nga and ddY mice, HR-1 mice showed less sensitivity to histamine than ICR mice. On the other hand, the HR-1 mice showed a high response to serotonin compared with those of the NC/Nga and ddY mice. The scratching behavior in HR-1 mice induced by substance P was increased, but the effect was less potent than those in NC/Nga, ICR, and ddY mice. These results suggest that the scratching behavior induced by compound 48/80 in HR-1 mice is mainly attributable to serotonin.

Potent pruritogenic action of tryptase mediated by PAR-2 receptor and its involvement in anti-pruritic effect of nafamostat mesilate in mice

The pruritogenic potency of tryptase and its involvement in anti-pruritic effect of intravenous nafamostat mesilate (NFM) were studied in mice. An intradermal injection of tryptase (0.05-1 ng/site) elicited scratching in ICR mice, while chymase was without effects at doses of 0.05-50 ng/site. The dose-response curve of tryptase action was bell-shaped and the effect peaked at 0.1 ng/site (approximately 0.7 fmol/site). NFM (10 mg/kg) inhibited scratching induced by tryptase but not by histamine and serotonin. NFM (1-10 mg/kg) produced the dose-dependent inhibition of scratching induced by intradermal compound 48/80 (10 microg/site). The inhibition by NFM (10 mg/kg) was abolished in mast cell-deficient (WBB6F1 W/W(V)) mice, but not in wild-type (WBB6F1 +/+) mice. NFM (10 mg/kg) suppressed tryptase activity in the mouse skin. Proteinase-activated receptor-2 (PAR-2) neutralizing antibody (0.1 and 1 microg/site) and the PAR-2 antagonist FSLLRY (10 and 100 microg/site) inhibited scratching induced by tryptase (0.1 ng/site) and compound 48/80 (10 microg/site). These results suggest that mast cell tryptase elicits itch through PAR-2 receptor and that NFM inhibits itch-associated responses mainly through the inhibition of mast cell tryptase.

Anti-allergic effects of Lycopus lucidus on mast cell-mediated allergy model

The current study characterizes the mechanism by which the aqueous extract of Lycopus lucidus Turcz. (Labiatae) (LAE) decreases mast cell-mediated immediate-type allergic reaction. The immediate-type allergic reaction is involved in many allergic diseases such as asthma and allergic rhinitis. LAE has been used as a traditional medicine in Korea and is known to have an anti-inflammatory effect. However, its specific mechanism of action is still unknown. LAE was anally administered to mice for high and fast absorption. LAE inhibited compound 48/80-induced systemic reactions in mice. LAE decreased the local allergic reaction, passive cutaneous anaphylaxis, activated by anti-dinitrophenyl (DNP) IgE antibody. LAE dose-dependently reduced histamine release from rat peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. Furthermore, LAE decreased the secretion of TNF-alpha and IL-6 in phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187-stimulated human mast cells. The inhibitory effect of LAE on the pro-inflammatory cytokine was p38 mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-kappaB) dependent. LAE attenuated PMA plus A23187-induced degradation of IkappaBalpha and nuclear translocation of NF-kappaB, and specifically blocked activation of p38 MAPK, but not that of c-jun N-terminal kinase and extracellular signal-regulated kinase. Our findings provide evidence that LAE inhibits mast cell-derived immediate-type allergic reactions and involvement of pro-inflammatory cytokines, p38 MAPK, and NF-kappaB in these effects.

The use of methylene blue in the treatment of anaphylactic shock induced by compound 48/80: experimental studies in rabbits

In this study, the isolated use of methylene blue (MB) in the treatment of anaphylactic shock induced by Compound 48/80 (C48/80), a potent histamine releaser, was examined, and the study of the effects of MB on the function of the aorta artery endothelium was accomplished in vitro. MB was used in a single 3.0 mg/kg dose, and C48/80 was used in a single 4.5 mg/kg dose. The study protocol included the following experimental groups, containing six animals each: group I (control), animals in the absence of any drug action; group II (MB), MB infusion; Group III (C48/80), anaphylactic shock induced by using C48/80; group IV (C48/80 + MB), anaphylactic shock treated with MB infusion at the moment of major hypotension; and group V (MB + C48/80), prevention of anaphylactic shock with MB by means of MB infusion minutes before the 4.5 mg/kg C48/80 infusion. Nitric oxide plasma levels were measured in each of the experimental groups. After the in vivo studies were performed, an in vitro study was conducted using segments of the abdominal aortas of the rabbits to determine the effect of MB on the arterial endothelium. The results obtained in the present investigation have shown that MB intravenous infusion does not change the mean arterial pressure when compared with the control group (n = 6 in each group, P < 0.05); that C48/80 is effective in producing experimental anaphylactic shock (n = 6, P < 0.05); that the attempt to prevent anaphylactic shock with MB results in a mean prolongation of animal survival ranging from 17 to 34 min (n = 6 in each group, P < 0.05); that MB is effective in reversing anaphylactic shock in all the studied rabbits (n = 6, P < 0.05); that absolute and percentage plasma nitrate values obtained with the experimental groups do not differ (n = 6, each group, P < 0.05); and that the in vitro study of segments of abdominal aorta has shown that there has not been endothelial dysfunction in any of the groups (n = 6 in each group, P < 0.05). The good results obtained in this study open a research path that may offer data to define new paradigms for treating anaphylaxis.

Plaunotol prevents the progression of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

We examined the preventive effect of plaunotol, an antiulcer drug, on acute gastric mucosal lesion progression in rats treated once with compound 48/80 (C48/80). Rats treated with C48/80 (0.75 mg/kg BW, i.p.) received plaunotol (10, 25 or 50 mg/kg BW, p.o.) 0.5 h after the treatment at which time gastric mucosal lesions appeared. The gastric mucosa of C48/80-treated rats showed progressed lesions and had increased myeloperoxidase (an index of neutrophil infiltration) activity and thiobarbituric acid reactive substances (an index of lipid peroxidation) content and decreased ascorbic acid and adherent mucus contents and Se-glutathione peroxidase activity at 3 h after C48/80 treatment. Postadministered plaunotol attenuated all these changes dose-dependently. These attenuating effects of plaunotol were not counteracted by pretreatment with indomethacin (5 mg/kg BW, i.p.), a prostaglandin synthesis inhibitor. These results indicate that plaunotol prevents the progression of C48/80-induced acute gastric mucosal lesions in rats possibly by its anti-inflammatory and antioxidant actions, but not by affecting gastric mucosal prostaglandin levels.

Effect of Gefarnate on Acute Gastric Mucosal Lesion Progression in Rats Treated with Compound 48/80, a Mast Cell Degranulator, in Comparison with That of Teprenone

We have reported that teprenone (geranylgeranylacetone), an anti-ulcer drug, prevents acute gastric mucosal lesion progression in rats treated once with compound 48/80 (C48/80), a mast cell degranulator, possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa. Herein, we examined the preventive effect of gefarnate (geranyl farnesylacetate), an anti-ulcer drug, on acute gastric mucosal lesion progression in rats treated once with C48/80 (0.75 mg/kg, i.p.) in comparison with that of teprenone, because the chemical structure and anti-ulcer action of gefarnate are similar to those of teprenone. Gefarnate (50, 100 or 200 mg/kg) administered orally at 0.5 h after C48/80 treatment, at which time gastric mucosal lesions appeared, reduced progressive gastric mucosal lesions at 3 h dose-dependently. At 3 h after C48/80 treatment, the gastric mucosa had decreased adherent mucus and hexosamine contents and increased myeloperoxdiase (an index of neutrophil infiltration) and xanthine oxidase activities and thiobarbituric acid reactive substances (an index of lipid peroxidation) content. Post-administered gefarnate attenuated all these changes dose-dependently. These preventive effects of gefarnate were similar to those of teprenone at a dose of 200 mg/kg. Post-administered gefarnate did not affect the increases in serum serotonin and histamine concentrations and the decrease in gastric mucosal blood flow at 3 h after C48/80 treatment like teprenone. These results indicate that orally administered gefarnate prevents acute gastric mucosal lesion progression in C48/80-treated rats possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa like teprenone.

Isodon japonicus inhibits mast cell-mediated immediate-type allergic reactions

The effect of aqueous extract of Isodon japonicus Hara (Labiatae) (IJAE) on mast cell-mediated immediate-type allergic reactions was investigated. IJAE inhibited systemic allergic reaction induced by compound 48/80. When IJAE was pretreated at the same concentrations with systemic allergic reaction test, the plasma histamine levels were reduced in a dose-dependent manner. IJAE also inhibited local allergic reaction activated by anti-dinitrophenyl (DNP) IgE antibody. IJAE dose-dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. IJAE inhibited the secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6 in phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187-stimulated human mast cell line (HMC-1) cells. In addition, the expression of TNF-alpha mRNA in HMC-1 cells was inhibited by IJAE. These results indicate that IJAE may be beneficial in the regulation of immediate-type allergic reaction.

Inhibitory activity of Chrysanthemi sibirici herba extract on RBL-2H3 mast cells and compound 48/80-induced anaphylaxis

The effects of extracts from various oriental medicinal herbs on mast cell-mediated allergic reaction were investigated. Among them, Chrysanthemi sibirici herba ethanol extract exerted the potent inhibitory activity on antigen-induced degranulation in RBL-2H3 mast cells. Chrysanthemi sibirici herba dose-dependently inhibited DNP-BSA or compound 48/80-induced degranulation in RBL-2H3 mast cells, with IC(50) values of approximately 49 microg/ml and 76 microg/ml, respectively. This extract strongly suppressed compound 48/80-induced systemic anaphylaxis by 48.7% at a dose of 300 mg/kg in mice. Chrysanthemi sibirici herba also inhibited the expression of TNF-alpha and the activation of the MAP kinase, ERK1/2, which is critical for the production of inflammatory cytokines in mast cells, as indicated by the suppression of activating phosphorylation of ERK1/2. These results lead us to conclude that Chrysanthemi sibirici herba may be used clinically to treat various allergic diseases.

Inhibitory Effect of Yunbutang on Mast Cell‐Dependent Allergic Reactions

Yunbutang (YB) is an Oriental herbal prescription, which has been successfully applied for the treatment of allergic disorders, mainly atopic dermatitis in clinical medicine. However, its effect in experimental models remains unknown. Here, we report inhibitory effects of YB on mast cell-dependent immediate-type allergic reactions. YB inhibited systemic allergic reaction induced by compound 48/80. YB dose-dependently inhibited the histamine release from the mast cells activated by compound 48/80. YB also showed an inhibitory effect of anti-dinitrophenyl IgE antibody-induced passive cutaneous anaphylaxis reaction by oral administration. Furthermore, YB inhibited tumor necrosis factor-alpha secretion from stimulated mast cells. These findings provide evidence that YB inhibits the mast cell-dependent allergic reactions.

Inhibition of Mast Cell‐Dependent Allergy Reaction by Extract of Black Cohosh (Cimicifuga racemosa)

Black cohosh (Cimicifuga racemosa) has been used as therapeutics for pain and inflammation in Korean folk medicine. The potential effects of black cohosh extract (BCE) on mast cell-dependent allergy reaction, however, have not been well elucidated yet. In the present study, we investigated the effect of BCE on the allergy reaction using mast cell-dependent in vivo and in vitro models. BCE showed no potential of skin sensitization in local lymph node assay (LLNA). The oral administration of BCE significantly inhibited the anti-IgE-induced passive cutaneous anaphylaxis (PCA) reaction. BCE also showed inhibitory potential on the compound 48/80-induced histamine release from rat peritoneal mast cells. In addition, BCE inhibited the IL-4, IL-5 and TNF-alpha mRNA induction by PMA and A23187 in human leukemia mast cells, HMC-1. These results demonstrated that BCE has an anti-allergic potential and it may be due to the inhibition of histamine release and cytokine gene expression in the mast cells.

Protective effect of teprenone against acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

The protective effect of teprenone, an anti-ulcer drug, against acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (0.75 mg/kg). Teprenone (50, 100, or 200 mg/kg) was orally administered 0.5 h before compound 48/80 treatment. Administered teprenone prevented gastric mucosal lesion development found at 3 h after compound 48/80 treatment dose-dependently, although no dose of teprenone affected the decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 3 h after the treatment. Increases in the activities of myeloperoxdiase (an index of neutrophil infiltration) and xanthine oxidase and the content of thiobarbituric acid reactive substances (an index of lipid peroxidation) and decreases in the contents of hexosamine (a marker of gastric mucus) and adherent mucus occurred in gastric mucosal tissues at 3 h after compound 48/80 treatment. Administered teprenone dose-dependently attenuated all these changes found at 3 h after compound 48/80 treatment. These results indicate that orally administered teprenone protects against compound 48/80-induced acute gastric mucosal lesions in rats possibly through its stimulatory action on gastric mucus synthesis and secretion and its inhibitory action on neutrophil infiltration and enhanced lipid peroxidation in the gastric mucosal tissue.

Inhibition of immunologic and nonimmunologic stimulation-mediated anaphylactic reactions by the aqueous extract of Mentha arvensis

The effect of aqueous extract of Mentha arvensis L. var. piperascens Malinv. (Labiatae) (MAAE) on immunologic and nonimmunologic stimulation-mediated anaphylactic reactions was studied. Nonimmunologic anaphylactic reaction was induced by compound 48/80 injection. MAAE (0.005 to 0.5 g/kg) inhibited systemic anaphylactic reaction induced by compound 48/80. Immunologic anaphylactic reaction was generated by sensitizing the skin with anti-dinitrophenyl (DNP) IgE followed 48 h later with an injection of antigen. MAAE (0.001 to 1 g/kg) dose-dependently inhibited passive cutaneous anaphylaxis (PCA) when intraperitoneally, intraveneously and orally administered. MAAE (0.001 to 1 mg/ml) dose-dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. Moreover, MAAE (0.1 mg/ml) had a significant inhibitory effect on anti-DNP IgE-mediated tumor necrosis factor-alpha (TNF-alpha) production. These results indicate that MAAE inhibits immunologic and nonimmunologic stimulation-mediated anaphylactic reactions and TNF-alpha production from RPMC.

A3 adenosine receptor knockout mice are protected against ischemia- and myoglobinuria-induced renal failure

A(3) adenosine receptor (AR) activation and inhibition worsen and improve, respectively, renal function after ischemia-reperfusion (I/R) injury in rats. We sought to further characterize the role of A(3) ARs in modulating renal function after either I/R or myoglobinuric renal injury. A(3) knockout mice had significantly lower plasma creatinines compared with C57 controls 24 h after I/R or myoglobinuric renal injury. C57 control mice pretreated with the A(3) AR antagonist [3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5 dicarboxylate] or agonist [0.125 mg/kg N(6)-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (IB-MECA)] demonstrated improved or worsened renal function, respectively, after I/R or myoglobinuric renal injury. Higher doses of IB-MECA were lethal in C57 mice subjected to renal ischemia. H(1) but not H(2) histamine receptor antagonist prevented death in mice pretreated with IB-MECA before renal ischemia. Improvement in renal function was associated with significantly improved renal histology. In conclusion, preischemic A(3) AR activation (0.125 mg/kg IB-MECA) exacerbated renal I/R injury in mice. Mice lacking A(3) ARs or blocking A(3) ARs in wild-type mice resulted in significant renal protection from ischemic or myoglobinuric renal failure.

Protective effect of ebselen, a seleno-organic compound, against the progression of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

The protective effect of ebselen, which possesses glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties, against the progression of acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (0.75 mg/kg). Ebselen (50, 100 or 200 mg/kg) was orally administered 0.5 h after compound 48/80 treatment, at which time gastric mucosal lesions appeared. Post-administered ebselen suppressed gastric mucosal lesion progression at 3 h after compound 48/80 treatment dose-dependently, although no dose of ebselen affected the decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 3 h after the treatment. A decrease in Se-glutathione peroxidase activity and increases in myeloperoxidase and xanthine oxidase activities and the concentration of thiobarbituric acid reactive substances were found in gastric mucosal tissues at 0.5 h after compound 48/80 treatment, and these changes were further enhanced at 3 h. Post-administered ebselen attenuated all these changes found at 3 h after compound 48/80 treatment dose-dependently. The present results indicate that ebselen exerts a protective effect against the progression of compound 48/80-induced acute gastric mucosal lesions in rats, and they suggest that this protective effect of ebselen could be due to its glutathione peroxidase-like activity and its antioxidative and anti-inflammatory properties.

Protective effect of omeprazole against acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

Omeprazole, a proton pump inhibitor is known to function not only as a proton pump inhibitor but also as an anti-inflammatory agent, an antioxidant or a stimulator of gastric mucus secretion. We have shown that the pathogenesis of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats involves neutrophil infiltration, lipid peroxidation, and mucin depletion, but not acid secretion, in the gastric mucosal tissue. Therefore, we examined whether omeprazole protects against acute gastric mucosal lesions induced by compound 48/80 in rats. Rats were injected with omeprazole (10 or 50 mgkg(-1), i.p.) at 0.5h before injection of compound 48/80 (0.75 mgkg(-1), i.p.). Omeprazole prevented gastric mucosal lesion development at 0.5 and 3h after compound 48/80 injection. Omeprazole attenuated decreased nonprotein sulfhydryl content and increased myeloperoxidase and xanthine oxidase (XO) activities and lipid peroxide (LPO) content in the gastric mucosa at 0.5h after compound 48/80 injection and increased myeloperoxidase and XO activities and LPO content, but not decreased hexosamine and adherent mucus contents, in the gastric mucosa at 3h. These results indicate that omeprazole protects against compound 48/80-induced acute gastric mucosal lesions in rats possibly through its anti-inflammatory and antioxidant actions.

Inhibition of immediate-type allergic reactions by Prunella vulgaris in a murine model

We studied the effect of aqueous extract of Prunella vulgaris (Labiatae) (PVAE) on immediate-type allergic reactions. PVAE (0.005 to 1 g/kg) dose-dependently inhibited systemic anaphylactic shock induced by compound 48/ 80 in rats. When PVAE was given as pretreatment, at concentrations ranging from 0.005 to 1 g/kg, the serum histamine levels induced by compound 48/ 80 were reduced in a dose-dependent manner. PVAE (0.001 to 1 g/kg) inhibited the passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) IgE antibody dose dependently. PVAE also inhibited the histamine release induced by compound 48/80 or anti-DNP IgE from the rat peritoneal mast cells (RPMC). The level of cyclic AMP in RPMC, when PVAE was added, significantly increased, compared with that of normal control. Moreover, PVAE (0.01 and 0.1 mg/ml) had a significant inhibitory effect on anti-DNP IgE-mediated tumor necrosis factor-alpha production from RPMC. These results indicate that PVAE inhibits immediate-type allergic reactions in rats.

Effect of fructose-1, 6-diphosphate versus diphenhydramine on mortality in compound 48/80-induced shock

Fructose-1,6-diphosphate (FDP) has a salutary effect on hemorrhagic, traumatic and endotoxic shock. The role of FDP on compound 48/80-induced shock was therefore investigated. Sprague Dawley aged male rats (448+/-7.4 gm body weight) were randomly assigned into three groups and treated intraperitoneally with diphenhydramine (DPHM) 15 mg/kg (n=11), 12.5 ml of 10% FDP (n=10) and 12.5 ml saline (n=10). The rats were injected with compound 48/80 (5 mg/kg) 30 min later, and monitored every 10 min for 60 min. Arterial pressure was higher in FDP rats than in DPHM (P<0.01) or saline (P<0.005) groups. Plasma potassium (K(+)) was lower in the FDP group (P<0.01). Arterial pO2 and pCO2 were within physiological range in all groups. A profound decrease in arterial pH and bicarbonate (HCO3(-)) was also observed in all groups. Mortality at 48 h in the saline group was 100%, in the DPHM group 91%, and in the FDP group 20% (P<0.001 and P<0.005, respectively). FDP improved survival significantly in this study.

Effect of Cryptotympana atrata extract on compound 48/80-induced anaphylactic reactions

We studied the effect of the aqueous extract of Cryptotympana atrata Fabricius on anaphylactic reactions. Cryptotympana atrata completely inhibited compound 48/80-induced systemic anaphylactic shock at doses of 0.5 and 1.0 g/kg. When Cryptotympana atrata was given as pretreatment at concentrations ranging from 0.025 to 1.0 g/kg, the plasma histamine levels induced by compound 48/80 were reduced in a dose-dependent manner. Cryptotympana atrata also inhibited histamine release from rat peritoneal mast cells (RPMC) by compound 48/80. In addition, when Cryptotympana atrata was added, the level of cAMP in RPMC transiently and significantly increased about 14-fold compared with that of control cells. Our studies provide evidence that Cryptotympana atrata may be beneficial in the treatment of nonspecific anaphylactic reactions.

Role of endogenous serotonin and histamine in the pathogenesis of gastric mucosal lesions in unanaesthetised rats with a single treatment of compound 48/80, a mast cell degranulator

In unanaethetised rats with a single injection of compound 48/80, a mast cell degranulator (0.75 mg kg-1, i.p.), gastric lesions occurred with increased serum serotonin and histamine levels and reduced gastric mucosal blood flow at 0.5 h after the injection and developed at 3 h. Pretreatment with either cyproheptadine (a serotonin and histamine antagonist) or methysergide (a serotonin antagonist) prevented the formation of gastric mucosal lesions with attenuation of reduced gastric mucosal blood flow at 0.5 h after compound 48/80 injection, while pretreatment with either amitriptyline (a selective inhibitor of histamine release from mast cells), tripelennamine (a histamine H1-receptor antagonist), famotidine (a histamine H2-receptor antagonist) or cimetidine (a histamine H2-receptor antagonist) had no effect. Pretreatment with either cyproheptadine, methysergide, amitriptyline or tripelennamine prevented the development of gastric mucosal lesions at 3 h after compound 48/80 injection, while pretreatment with either famotidine or cimetidine had no effect. These results indicate that in unanaesthetised rats with a single compound 48/80 treatment, acutely released endogenous serotonin causes gastric mucosal lesions, while released endogenous histamine mainly contributes to the lesion development and that gastric acid plays little role in the pathogenesis of the compound 48/80-induced acute gastric lesions.

Mast cell stabilizing and lipoxygenase inhibitory activity of Cedrus deodara (Roxb.) Loud. wood oil

Volatile oil of C. deodara, administered orally at the doses of 50, 100 and 200 mg/kg body weight, significantly inhibited the pedal edema induced by compound 48/80 in rats. The oil significantly inhibited compound 48/80 induced degranulation of isolated rat peritoneal mast cells at concentrations ranging from 25-200 micrograms/ml. C. deodara wood oil also significantly inhibited the enzyme lipoxygenase at a concentration of 200 micrograms/ml. Thus, the anti-inflammatory activity of C. deodara wood oil could be attributed to its mast cell stabilizing activity and the inhibition of leukotriene synthesis.

Magnoliae flos inhibits mast cell-dependent immediate-type allergic reactions

The mast cell plays a pivotal role in initiating allergic response by secreting intracytoplasmic granular mediators such as histamine. Magnoliae flos has been used for the treatment of allergic disease in Korea. However, its effect in experimental models remains unknown. The present report describes an inhibitory effect of Magnoliae flos on mast cell-mediated immediate-type allergic reactions. Topical application of compound 48/80 can induce an ear swelling response in normal (WBB6F1-+/+) mice but not in the congenic mast cell-deficient WBB6F1-W/Wv mice. Magnoliae flos inhibited concentration-dependently mast cell-dependent ear swelling response induced by compound 48/80 by topical application. Magnoliae flos inhibited concentration-dependently passive cutaneous anaphylaxis induced by anti-dinitrophenyl (DNP) IgE in rats by topical application. Magnoliae flos also inhibited concentration-dependently the histamine release from the rat peritoneal mast cells by compound 48/80 or anti-DNP IgE. Moreover, Magnoliae flos had a significant inhibitory effect on compound 48/80-induced systemic anaphylactic reaction. These results indicate that Magnoliae flos inhibits immediate-type allergic reactions by inhibition of mast cell degranulation in vivo and in vitro.

Inhibitory effect of anaphylactic reaction of Sosiho-Tang

Mast cells synthesize and secrete chemical mediators which play an central role in anaphylactic reactions. Compound 48/80 is a condensation product of formaldehyde with paramethoxyphenylethylamine that reliably induces the release of chemical mediators in the mast cell granules. Aggregation of the high-affinity Fc receptor also stimulates the mast cells. The objective of the current study was to determine the effect of Sosiho-Tang (SS-Tang) on mast cell-mediated anaphylactic reaction. SS-Tang completely inhibited systemic anaphylaxis induced by compound 48/80 in mice. SS-Tang inhibited local anaphylaxis induced by anti-dinitrophenyl (DNP) IgE. In addition SS-Tang concentration-dependently inhibited histamine release in mast cells induced by compound 48/80 or anti-DNP IgE. These results indicate that SS-Tang may contain compounds with actions that inhibit mast cell degranulation.

Synthesis and structure-activity relationships of a new series of benzimidazoles as H1-antihistaminic agents

New 2-(4-(4-azolylbutyl)piperazinyl)-, 2-(4-(4-azolylbutyl) piperazinylmethyl)-, 2-(4-(-azolylbutyl)homopiperazinyl)- and 2-(4-(4-azolylbutyl)homopiperazinylmethyl)benzimidazoles were synthesized, characterized and tested for in vitro and in vivo H1-antihistaminic activity. Structure-activity relationships implied that the best antihistaminic activity required the simultaneous presence of a homopiperazinylbenzimidazole system (or a methylene linker between the benzimidazole and the piperazine rings) and an unsubstituted pyrazole ring. 1-(2-Ethoxyethyl)-2-¿4-[4-(pyrazol-1-yl)butyl] homopiperazin-1-yl¿benzimidazole (17), as its dimaleate salt, has been chosen for further development.

Relationship between changes of active oxygen metabolism and blood flow and formation, progression, and recovery of lesions is gastric mucosa of rats with a single treatment of compound 48/80, a mast cell degranulator

The relationship between the changes of active oxygen metabolism and blood flow and the formation, progression, and recovery of lesions was examined in the gastric mucosa of rats treated once with compound 48/80, a mast cell degranulator. Gastric mucosal lesions appeared 0.5 hr after compound 48/80 treatment, became worst at 3 hr, and recovered fairly well at 12 hr. Increases in gastric mucosal lipid peroxide content and xanthine oxidase and myeloperoxidase activities and decreases in gastric mucosal vitamin E and hexosamine contents and Se-dependent glutathione peroxidase activity occurred with the formation and progression of gastric mucosal lesions. These changes were attenuated with the recovery of the lesion. Gastric mucosal nonprotein SH content decreased with the formation of gastric mucosal lesions, and this decreased SH content returned to near the original level with lesion progression. No changes in gastric mucosal superoxide dismutase and catalase activities occurred with the formation, progression, and recovery of gastric mucosal lesions. Gastric mucosal blood flow decreased with the formation of gastric mucosal lesions, and this decreased blood flow recovered with lesion progression. Serum serotonin concentration, an index of mast cell degranulation, increased with the formation of gastric mucosal lesions, and this increased serotonin level was attenuated with lesion progression and recovery. Pretreatment with ketotifen, a connective tissue mast cell stabilizer, prevented the formation of gastric mucosal lesions, the increases of gastric mucosal lipid peroxide content, xanthine oxidase and myeloperoxidase activities, and serum serotonin level; and the decreases of gastric mucosal nonprotein SH content, glutathione peroxidase activity, and blood flow found at 0.5 hr after compound 48/80 treatment. These results indicate that the changes of gastric mucosal active oxygen metabolism and blood flow are closely related to the formation, progression, and recovery of gastric mucosal lesions in rats with a single compound 48/80 treatment. The present results also suggest that this compound 48/80-induced gastric mucosal injury could be a kind of ischemia-reperfusion-induced injury occurring through degranulation of connective tissue mast cells.

Dietary modulation of fatty acid composition of mast cell phospholipids does not affect histamine release induced by compound 48/80

OBJECTIVE AND DESIGN

In the present study we determined the extent to which the degranulation process in mast cells was related to the fatty acid composition of membrane phospholipids.

MATERIAL

Peritoneal mast cells were isolated from Wistar rats (3 groups of 18 animals each), fed for 6 weeks diets which differed in their fatty acid compositions: (i) genuine salmon oil, abundant in (n-3) fatty acids, (ii) sunflower seed oil, rich in (n-6) fatty acids, particularly linoleic acid, and (iii) hydrogenated coconut oil, rich in saturated fatty acids.

METHODS

Mast cells (10(6)/ml) were stimulated with various concentrations of the mast cell-degranulating agent, compound 48/80 (0.1-10 micrograms/ml). The extent of mast cell degranulation was quantified by determination of histamine in the supernatants using HPLC techniques.

RESULTS

No differences in compound 48/80-induced histamine release between the three dietary groups for any of the concentrations of compound 48/80 tested were found. Analysis of variance followed by Tukey's method for multiple comparisons was used to evaluate the effect of changes in the dietary fat type.

CONCLUSION

These findings strongly suggest that in contrast to the formation of eicosanoids, the process of mast cell degranulation by a receptor-independent pathway is not controlled by the fatty acid composition of membrane phospholipids.

Topical cyclosporine inhibits mast cell-mediated conjunctivitis

PURPOSE

Allergic conjunctivitis is a common condition caused by a mast cell-mediated hypersensitivity reaction to immunoglobulin E-bound allergens. The purpose of this study was to investigate the effect of topical cyclosporine A on the development of mast cell-mediated conjunctivitis in mice.

METHODS

Allergic conjunctivitis was induced in C57BL/6 mice by topical applications of compound 48/80, a mast cell degranulating agent. In two separate experiments, mice were treated with topical cyclosporine A (0.05%, 0.2%, or 0.4%), prednisolone acetate 1%, or phosphate-buffered saline. Twenty-four hours after compound 48/80 instillation, the number of neutrophils, eosinophils, lymphocytes, macrophages, and the number of preserved goblet cells and undegranulated mast cells in the conjunctiva were counted by a masked observer.

RESULTS

In both experiments, treatment with all three doses of cyclosporine A resulted in a statistically significant reduction in the number of infiltrating neutrophils and eosinophils compared to saline-treated controls. There was no significant difference in the treatment effect of cyclosporine and prednisolone acetate. In addition, there was increased preservation of goblet cells in the cyclosporine A-treated animals. Immunohistochemical staining showed a reduction in infiltrating lymphocytes and a smaller reduction in infiltrating macrophages in animals treated with cyclosporine compared to saline-treated controls.

CONCLUSIONS

Topical cyclosporine A was effective in inhibiting the development of mast cell-mediated allergic conjunctivitis in mice. This study suggests that topical cyclosporine A may be effective in treating allergic conjunctivitis in humans.

Effects of E-4716, a new antihistaminic with antiallergic properties, on chemical mediators induction of immunologic reactions

The effects of E-4716 on chemical mediators were compared with those of classical antihistaminics and other second generation (nonsedating) drugs normally used in the therapy of allergic reactions, such as astemizole, terfenadine and ebastine, in a series of in vitro and in vivo tests. In vitro, antihistaminic activity was demonstrated in a test on isolated organs and a binding test on histamine receptors, with no anticholinergic activity observed. A high antihistaminic activity was also shown in in vivo tests on chemical mediators release by compound 48/80, histamine-induced bronchospasm in anesthetized guinea pigs and histamine-induced cutaneous reaction in beagle dogs. The antiallergic activity was studied in passive cutaneous anaphylaxis test using ovalbumin antibodies. Astemizole and E-4716 had similar activities with ED50 values of 0.8 and 0.5 mg/kg, respectively, whereas terfenadine (ED50 = 4.5) was less active. E-4716 also inhibited the vascular permeability response in histamine-stimulated conjunctivitis model after topical ocular administration (ED50 = 0.002, 0.0002, 0.015 and 1.2% at 30 min and 6, 12 and 24 h, respectively). E-4716 had a high and selective antihistaminic and antiallergic activity by all routes of administration (oral, i.v., i.p., topical ocular and inhalation). These results, combined with its low toxicity and lack of central effects, indicate that E-4716 has excellent potential for therapeutic use.

Compound 48/80-induced conjunctivitis in the mouse: kinetics, susceptibility, and mechanism

A mouse model of conjunctivitis has been developed by topical application of compound 48/80 (C48/80), an agent that triggers mast cell degranulation. We examined the responsiveness of C57BL/6, C3H/HeN, and ASW/J mouse strains to C48/80 stimulation, and of a mutant strain with mast cell depletion (WBB6F1/J and its sham control). Conjunctivae were collected and examined histopathologically at 15 min and 1,6,24,48 and 72 h after topical C48/80 administration. Conjunctival inflammation developed in all strains, although the severity varied. The conjunctivitis was characterized clinically by irritation, discharge, erythema, and chemosis. Pathology showed conjunctival infiltration with neutrophils, macrophages, CD4+ T lymphocytes, and a few eosinophils. Degranulation of mast cells and evacuation of goblet cells were also observed. Late-phase inflammatory reactions peaked 6-24 h after C48/80 administration and resolved by 48-72 h. WBB6F1/J mice had much less inflammation than their sham controls. In conclusion, topical C48/80 induced a conjunctival inflammatory response similar to allergen-induced conjunctivitis. The depletion of mast cells significantly reduced the inflammation. This model which consistently mimics the clinical signs and histopathological processes of allergic conjunctivitis in humans, is practical and reliable for the evaluation of new anti-allergic medications and for the investigation of conjunctival cellular responses in the allergic inflammatory cascade.

Pleural fluid eosinophils suppress local IgE-mediated protein exudation in rats

Eosinophils are supposed to play a critical role in the pathology of several allergic diseases because after activation they can release toxic and proinflammatory agents. In this study we have investigated whether IgE-mediated rat pleurisy could be affected by an ongoing pleural eosinophilic inflammatory response. IgE-passively sensitized rats were challenged with an intrapleural (i.pl.) injection of allergen (dinitrophenylated bovine serum albumin, 1 microgram/cavity) and exudation assessed by measuring the amount of protein extravasated into the pleural cavity within 4 h. We have confirmed that lipopolysaccharide (LPS) stimulation (250 ng/cavity i.pl.) was followed by a marked pleural neutrophilia, apparent at 3 h, which was followed by an eosinophil accumulation noted within 48-72 h postchallenge. We have also confirmed that a boiled sample of LPS pleural washing (LPS-PW, 200 microliters i.pl.) caused selective eosinophilia in recipient rats. Pleural exudation remained unaltered when the allergenic challenge was performed 3 h after LPS in a condition of intense pleural fluid neutrophilia. In contrast, this was significantly reduced (P < .001) when the challenge occurred 72 h after LPS or 24 h after LPS-PW in selective pleural fluid eosinophilia. In another series of experiments repeated daily i.pl. injections of platelet-activating factor (PAF; 1 microgram/cavity) resulted in a progressive increase in eosinophil number recovered from the pleural cavity. The values were 1.2 +/- 0.2, 3.0 +/- 0.2, and 5.8 +/- 0.5 x 10(6) eosinophils/cavity (mean +/- SEM) after 0, 1, and 4 injections, respectively. Allergen challenge performed after 0, 1, or 4 PAF stimulations led to pleural protein levels of 88.6 +/- 5.7, 33.7 +/- 0.7, and 19.4 +/- 2.3 mg/cavity, respectively, indicating that the allergic pleurisy is inhibited in a manner dependent on the magnitude of eosinophil accumulation. Furthermore, the impairment of PAF-induced eosinophil accumulation by cetirizine (30 mg/kg i.p.) restored the exudatory response. Exudation triggered by compound 48/80 (25 micrograms/cavity), histamine (200 micrograms/cavity), or 5-hydroxytryptamine (100 micrograms/cavity) was not affected by four previous PAF daily injections. The findings indicate that allergen-induced exudation is selectively down-regulated in the eosinophil-enriched pleural space of rats, a suppression that increased with increasing eosinophil number and disappeared after chemical impairment of the eosinophilia.

Anti-anaphylactic activity of the novel selective histamine H1 receptor antagonist mizolastine in the rodent

The anti-anaphylactic/anti-histamine activity of mizolastine (CAS 108612-45-9, SL 85.0324), a novel histamine H1 receptor antagonist devoid of sedative properties, has been evaluated in the rat, mouse and guinea pig. Mizolastine inhibited the passive cutaneous anaphylactic reduction caused by ovalbumin challenge in the rat (ED50 = 0.7 mg/kg i.v., 1.6 mg/kg p.o.) and effectively protected rats from the lethal shock induced by compound 48/80 (ED50 = 0.07 mg/kg p.o.). Mizolastine protected actively sensitized guinea pigs from anaphylactic mortality, bronchospasm and respiratory difficulties (increase in pulmonary resistance) preceding this event and from morphological modifications at doses from 0.05 mg/kg i.v. The pharmacological activity of mizolastine is linked to a selective blockade of histamine H1 receptors as indicated by the ability of this compound to antagonize rat paw edema induced by the subplantar injection of histamine (ED50 = 0.5 mg/kg p.o.) but not that induced by the injection of serotonin or bradykinin. Mizolastine also antagonized the increase in cutaneous capillary permeability caused by the intradermal injection of histamine (-80% at 0.3 mg/kg p.o.) and compound 48/80 (ED50 = 1.1 mg/kg p.o.) but not that induced by serotonin in the rat. In the guinea pig, mizolastine antagonized i.v. histamine-induced bronchoconstriction (ED50 = 0.03 mg/kg p.o.) and histamine-induced vascular permeability and edema in trachea and bronchi (ED50 < or = 0.05 mg/kg i.v.). Moreover, at higher doses, mizolastine antagonized the bronchospasm caused by systemic injection of platelet-activating factor (PAF) and leukotriene D4 (LTD4) (ED50's = 0.30 and 3.0 mg/kg p.o., respectively). However, mizolastine only weakly antagonized bronchospasm induced by aerosolized PAF (-67% at 50 mg/kg p.o.), failed to antagonize (up to 3 mg/kg i.v.) PAF-induced microvascular permeability of the tracheal mucosa in the guinea pig and was a weak inhibitor of PAF-induced platelet aggregation in the rabbit (IC50 = 74 mumol/l). In addition to antagonizing histamine H1 receptors, mizolastine also inhibits the release of histamine during allergic reactions in tissues. Thus, mizolastine antagonizes the antigen-induced in vivo release of histamine from mast cells in bronchoalveolar lavages of actively sensitized guinea pigs (minimal effective dose 0.3 mg/kg p.o.) and the release of histamine from mast cells in the peritoneal fluid of passively sensitized rats (ED50 = 0.9 mg/kg i.v.). In these various models, mizolastine was more potent than loratadine and terfenadine but less potent than ketotifen. The apparent half-life for the pharmacological actions of mizolastine ranged from 6 to 8 h.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition by actinomycin D of neurogenic mouse ear oedema

We have investigated the effects of actinomycin D on mouse ear oedema induced by capsaicin, neuropeptides, and established inflammatory mediators. Actinomycin D (0.5 mg/kg, i.v.) significantly (P < 0.01) inhibited ear oedema induced by topical application of capsaicin, while adriamycin (6.0 mg/kg, i.v.) and cycloheximide (6.0 mg/kg, i.v.) had no effect on oedema. The ear oedema induced by intradermal injection of neuropeptides such as mammalian tachykinins, calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP), was markedly (P < 0.05, P < 0.01 or P < 0.001) suppressed by actinomycin D. The drug was also effective (P < 0.01 or P < 0.001) in inhibiting bradykinin (BK)- and compound 48/80-induced ear oedema, but did not inhibit oedema induced by histamine, 5-HT, leukotriene C4 (LTC4), and platelet activating factor (PAF) at a dose of 1 mg/kg. In mast cell-deficient W/WV mice, actinomycin D (1.0 mg/kg, i.v.) failed to inhibit substance P (SP)-induced ear oedema whereas spantide (0.5 mg/kg, i.v.) was an effective (P < 0.01) inhibitor of oedema formation. Furthermore, actinomycin D (10-100 microM) dose-dependently prevented histamine release from rat peritoneal mast cells evoked by SP, compound 48/80, and the ionophore A23182, respectively. These results strongly suggest that an inhibitory effect of actinomycin D on neurogenic inflammation is due primarily to the prevention of mast cell activation mediated by neuropeptides, rather than an interaction with DNA or receptors of neuropeptides.