Anti-anaphylactic action of nordihydroguaiaretic acid in antigen sensitized guinea pigs.

Therapeutic natural products and medicinal herbs has gained popularity. The anti-antigenic action of the plant alkaloid nordihydroguaiaretic acid (NDGA) was studied in ovalbumin (OA)-sensitized guinea pigs. In one series of experiments conscious, non-sedated guinea pigs were challenged with OA aerosol. Specific airway resistance (SRAW) was monitored using a two-chambered whole-body plethysmograph. OA aerosol increased SRAW above that produced by vehicle administration. Prior NDGA administration by a 1min 0.9% aerosol (w/vol) attenuated the increase in SRAW resulting from OA challenge. In the anesthetized guinea pig pretreated with indomethacin, pyrilamine and propranolol, intravenous OA injection increased intra-tracheal pressure above vehicle injection. Intravenous NDGA administration (5mg/kg) reduced the intra-tracheal pressure increases. In a third series of experiments plasma leukotriene C4 was measured by radio-immunoassay in 3 groups challenged with OA aerosol: vehicle-treated OA-sensitized, OA-sensitized receiving NDGA and vehicle treated guinea pigs. NDGA pretreatment reduced plasma LTC4 in response to OA challenge in OA sensitized guinea pigs. This study demonstrates that NDGA is an effective antigenic agent when given by aerosol or intravenous injection in either conscious or anesthetized guinea pigs, respectively. The mechanism of action of NDGA is presumed primarily be due to the blockage of 5-lipoxygenase and therefore the synthesis of leukotrienes.

Leukotriene production profiles and actions in the bovine endometrium during the oestrous cycle.

We have previously shown the influence of leukotrienes (LTs) on reproductive functions in vivo: LTB4 is luteotrophic and supports corpus luteum function inducing PGE2 and progesterone (P4) secretion, whereas LTC4 is luteolytic and stimulates PGF2α secretion in cattle. The aim of this study was to examine expression and production profiles of LTs and their actions in the endometrium. LT receptors (LTB4R for LTB4 and CysLTR2 for LTC4), 5-lipoxygenase (LO), 12-LO synthase (LTCS) and LTA4 hydrolase (LTAH) mRNA and protein expression, as well as LT production were measured in bovine endometrial tissue during the luteal phases of the oestrous cycle. The action of LTs on uterine function was studied by measuring the level of PGs after stimulating uterine slices with LTs on Days 8-10 of the cycle. Expression of 5-LO and LTB4R mRNA and protein were highest on Days 2-4 of the cycle, while CysLTR2 and LTCS were highest on Days 16-18 (P<0.05). LTB4 concentration was highest on Days 2-4 of the cycle, whereas the greatest LTC4 level was on Days 16-18 (P<0.05). Both LTB4 and C4 increased the content of PGE2 and F2α in endometrial slices at a dose of 10(-7)M (P<0.05). In summary, mRNA expression and activation of receptors for LTB4 and production occur in the first part of the cycle, whereas LTC4 and its receptors predominate at the end of the cycle. The 12-LO and 5-LO pathways are complementary routes of LT production in the bovine uterus.

Anti-inflammatory constituents from Perovskia atriplicifolia.

CONTEXT: Perovskia atriplicifolia Benth (Labiantae) has long been used as a traditional herbal medicine for anti-inflammation in Pakistan; this prompted us to isolate anti-inflammatory compounds from this plant. OBJECTIVE: The objective of this study was to isolate and characterize the anti-inflammatory principles from Perovskia atriplicifolia. MATERIALS AND METHODS: The CHCl3-soluble fraction of the methanol extract of the whole plant on column chromatography yielded compounds 1-6. The anti-inflammatory potential of the compounds 1-6 was evaluated by Leukotriene C4 (LTC4) Release Assay which was performed according to the established protocol. LTC4 in the supernatant of each well was measured using an ELISA kit (Cayman Chemical Co., Ann Arbor, MI). RESULTS: The bioassay-guided phytochemical investigation of the CHCl3 soluble fraction of the methanol extract of Perovskia atriplicifolia furnished six compounds, abrotanone (1), abrotandiol (2), (+)-pinoresinol (3), (+)-syringaresinol (4), (+)-lariciresinol (5), and (+)-taxiresinol (6). The compounds (1-6) were evaluated for their inhibitory activities on LTC4 release. Among the tested compounds, (+)-taxiresinol (6) exhibited the most potent inhibition of LTC4 release with an IC50 value of 3.4 ± 0.09 µM followed by compounds 4, 5, 3, and 2 with an IC50 value ranging from 7.9 ± 0.04 to 17.2 ± 0.07 µM. Abrotanone (1) showed the lowest inhibition of LTC4 release with an IC50 value of 35.1 ± 0.05 µM (the positive control, zileuton, 0.77 ± 0.05 µM). CONCLUSION: Compounds 1-6 were found to possess inhibitory activity and seem to have potential therapeutic effect on inflammatory diseases.

Cinnamaldehyde is the main mediator of cinnamon extract in mast cell inhibition.

PURPOSE: In terms of their involvement in allergic and inflammatory conditions, mast cells (MC) can be promising targets for medical agents in therapy. Because of their good compliance and effectiveness, phytochemicals are of great interest as new therapeutic tools in form of nutraceuticals. We found recently that cinnamon extract (CE) inhibits mast cell activation. Here, we analysed the effects of a major compound of CE, cinnamaldehyde (CA), on mast cell activation. METHODS: Release of prestored and de novo synthesised mediators as well as expression of pro-inflammatory cytokines and mast cell-specific proteases were analysed in RBL-2H3 cells or in human mast cells isolated from intestinal tissue (hiMC) treated with CA prior to stimulation by FcεRI crosslinking or IONO/PMA. The results were compared with the corresponding effects of CE. RESULTS: Following treatment with CA, release of ß-hexosaminidase in IgE-dependent or IgE-independent activated RBL-2H3 cells was down-regulated in a dose-dependent manner to about 10%. In hiMC, release of ß-hexosaminidase was also significantly reduced, and release of LTC4 and CXCL8 was almost completely inhibited by CA. Moreover, IgE-mediated expression of CXCL8, CCL2, CCL3 and CCL4 in hiMC was significantly down-regulated by CA. With the exception of the expression of the mast cell proteases tryptase and chymase, the inhibitory effects of CA were very similar to the effects shown for CE treatment. The reducing effect of CA on mast cell mediators-seen for long- and for short-term incubations-could be related to particular signalling pathways as CA caused a down-regulation in ERK as well as PLCγ1 phosphorylation. CONCLUSIONS: CA decreases release and expression of pro-inflammatory mast cell mediators. This inhibitory action is similar to the effects observed for CE indicating CA as the main active compound in CE leading to its anti-allergic properties.

Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4.

Calcium/voltage-gated, large conductance potassium (BK) channels control numerous physiological processes, including myogenic tone. BK channel regulation by direct interaction between lipid and channel protein sites has received increasing attention. Leukotrienes (LTA4, LTB4, LTC4, LTD4, and LTE4) are inflammatory lipid mediators. We performed patch clamp studies in Xenopus oocytes that co-expressed BK channel-forming (cbv1) and accessory ß1 subunits cloned from rat cerebral artery myocytes. Leukotrienes were applied at 0.1 nm-10 µm to either leaflet of cell-free membranes at a wide range of [Ca(2+)]i and voltages. Only LTB4 reversibly increased BK steady-state activity (EC50 = 1 nm; Emax reached at 10 nm), with physiological [Ca(2+)]i and voltages favoring this activation. Homomeric cbv1 or cbv1-ß2 channels were LTB4-resistant. Computational modeling predicted that LTB4 docked onto the cholane steroid-sensing site in the BK ß1 transmembrane domain 2 (TM2). Co-application of LTB4 and cholane steroid did not further increase LTB4-induced activation. LTB4 failed to activate ß1 subunit-containing channels when ß1 carried T169A, A176S, or K179I within the docking site. Co-application of LTB4 with LTA4, LTC4, LTD4, or LTE4 suppressed LTB4-induced activation. Inactive leukotrienes docked onto a portion of the site, probably preventing tight docking of LTB4. In summary, we document the ability of two endogenous lipids from different chemical families to share their site of action on a channel accessory subunit. Thus, cross-talk between leukotrienes and cholane steroids might converge on regulation of smooth muscle contractility via BK ß1. Moreover, the identification of LTB4 as a highly potent ligand for BK channels is critical for the future development of ß1-specific BK channel activators.

Anti-inflammatory terpenes from flowers of Inula japonica.

Five new terpenes (1-5) and ten known compounds (6-15) were isolated from Inula japonica, and their structures were identified by spectroscopic analysis. Compounds 3 and 14 showed positive inhibitory effects on nitric oxide production. Furthermore, compound 14 suppressed both leukotriene C4 synthesis and degranulation in c-kit ligand-induced bone marrow-derived mast cells.

Saucerneol D inhibits eicosanoid generation and degranulation through suppression of Syk kinase in mast cells.

Previously we reported that saucerneol D (SD), a naturally occurring sesquilignan isolated from Saururus chinensis (S. chinensis) suppressed lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells. The aim of this study was to elucidate whether SD modulates the generation of other inflammatory mediators in activated mast cells. We investigated the effects of SD on cyclooxygenase-2 (COX-2)-dependent prostaglandin D(2) (PGD(2)) and 5-lipoxygenase (5-LO)-dependent leukotriene C(4) (LTC(4)) generations as well as degranulation in cytokine-stimulated mouse bone marrow-derived mast cells (BMMCs). Biochemical analyses of the cytokine-mediated signaling pathways showed that SD suppressed the phosphorylation of Syk kinase and multiple downstream signaling processes including phospholipase Cγ1 (PLCγ1)-mediated intracellular Ca(2+) influx and activation of mitogen-activated protein kinases (MAPKs; including extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun NH(2)-terminal kinase (JNK) and p38) and the nuclear factor-κB (NF-κB) pathway. Taken together, the present study suggests that SD suppresses eicosanoid generation and degranulation through Syk-dependent pathway in BMMCs.

Anti-inflammatory and anti-allergic effect of Agaricus blazei extract in bone marrow-derived mast cells.

In this study, the anti-inflammatory and anti-allergic effects of the chloroform-soluble extract of Agaricus blazei in mouse bone marrow-derived mast cells (BMMCs) were investigated. The chloroform-soluble extract inhibited IL-6 production in PMA plus A23187-stimulated BMMCs, and down-regulated the phosphorylation of Akt. In addition, this extract demonstrated inhibition of the degranulation of ß-hexosaminidase and the production of IL-6, prostaglandin D(2) and leukotriene C(4) in PMA plus A23187-induced BMMCs. In conclusion, the chloroform-soluble extract of Agaricus blazei exerted anti-inflammatory and anti-allergic activities mediated by influencing IL-6, prostaglandin D(2), leukotriene C(4), and the phosphorylation of Akt.

Macelignan inhibits histamine release and inflammatory mediator production in activated rat basophilic leukemia mast cells.

Type I allergy is characterized by the release of granule-associated mediators, lipid-derived substances, cytokines, and chemokines by activated mast cells. To evaluate the anti-allergic effects of macelignan isolated from Myristica fragrans Houtt., we determined its ability to inhibit calcium (Ca(2+)) influx, degranulation, and inflammatory mediator production in RBL-2 H3 cells stimulated with A23187 and phorbol 12-myristate 13-acetate. Macelignan inhibited Ca(2+) influx and the secretion of ß-hexosaminidase, histamine, prostaglandin E(2), and leukotriene C(4); decreased mRNA levels of cyclooxygenase-2, 5-lipoxygenase, interleukin-4 (IL-4), IL-13, and tumor necrosis factor-α; and attenuated phosphorylation of Akt and the mitogen-activated protein kinases extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. These results indicate the potential of macelignan as a type I allergy treatment.

Leukotriene C4 induces migration of human monocyte-derived dendritic cells without loss of immunostimulatory function.

Generation of human monocyte-derived dendritic cells (DCs) for cancer vaccination involves ex vivo maturation in the presence of proinflammatory cytokines and prostaglandin E(2) (PGE(2)). Although the inclusion of PGE(2) during maturation is imperative for the induction of DC migration, PGE(2) has unfavorable effects on the immunostimulatory capacity of these cells. Like PGE(2), leukotrienes (LTs) are potent mediators of DC migration. We therefore sought to characterize the migratory and immunologic properties of DCs that matured in the presence of LTB(4), LTC(4), LTD(4), and PGE(2). Here, we demonstrate that DCs matured in the presence of LTC(4), but not LTB(4) or LTD(4), are superior to PGE(2)-matured DCs in stimulating CD4(+) T-cell responses and in inducing antigen-specific cytotoxic T lymphocytes (CTLs) in vitro without concomitant induction or recruitment of regulatory T cells (Tregs). LTC(4)-matured DCs migrate efficiently through layers of extracellular matrix and secrete higher levels of immunostimulatory IL-12p70 while producing reduced levels of immune-inhibitory IL-10, IL12p40, indoleamine-2,3-dioxidase, and TIMP-1 (tissue inhibitor of matrix metalloproteinases). Intracellular calcium mobilization and receptor antagonist studies reveal that, in contrast to LTD(4), LTC(4) did not signal through CysLTR(1) in DCs. Collectively, our data suggest that LTC(4) represents a promising candidate to replace PGE(2) in DC maturation protocols for cancer vaccination.

Anti-allergic effect of a chloroform-soluble extract of Cinnamomum cambodianum in bone marrow-derived mast cells.

Cinnamomum cambodianum has been used as a traditional medicine in Cambodia. Its effect on the bone marrow-derived mast cells (BMMCs) mediated allergic response remains unknown. In this study, a chloroform-soluble extract of C. cambodianum was evaluated for its effect on allergic mediators, including prostaglandin D2 (PGD2), leukotriene C4 (LTC4), ß-hexosaminidase and cyclooxygenase-2 (COX-2) protein, in phorbol 12-myristate 13-acetate (PMA) plus calcimycin-stimulated BMMCs. The results revealed that the chloroform-soluble extract inhibited the production of interleukin-6, PGD2 and LTC4, and the expression of COX-2 in PMA plus calcimycin-stimulated BMMCs, implying a potential benefit of C. cambodianum in the treatment of allergy.

Bioassay-guided identification of an anti-inflammatory prenylated acylphloroglucinol from Melicope ptelefolia and molecular insights into its interaction with 5-lipoxygenase.

A bioassay-guided investigation of Melicope ptelefolia Champ ex Benth (Rutaceae) resulted in the identification of an acyphloroglucinol, 2,4,6-trihydroxy-3-geranylacetophenone or tHGA, as the active principle inhibiting soybean 15-LOX. The anti-inflammatory action was also demonstrated on human leukocytes, where the compound showed prominent inhibitory activity against human PBML 5-LOX, with an IC(50) value of 0.42 µM, very close to the effect produced by the commonly used standard, NDGA. The compound concentration-dependently inhibited 5-LOX product synthesis, specifically inhibiting cysteinyl leukotriene LTC(4) with an IC(50) value of 1.80 µM, and showed no cell toxicity effects. The anti-inflammatory action does not seem to proceed via redox or metal chelating mechanism since the compound tested negative for these bioactivities. Further tests on cyclooxygenases indicated that the compound acts via a dual LOX/COX inhibitory mechanism, with greater selectivity for 5-LOX and COX-2 (IC(50) value of 0.40 µM). The molecular features that govern the 5-LOX inhibitory activity was thus explored using in silico docking experiments. The residues Ile 553 and Hie 252 were the most important residues in the interaction, each contributing significant energy values of -13.45 (electrostatic) and -5.40 kcal/mol (electrostatic and Van der Waals), respectively. The hydroxyl group of the phloroglucinol core of the compound forms a 2.56Å hydrogen bond with the side chain of the carboxylate group of Ile 553. Both Ile 553 and Hie 252 are crucial amino acid residues which chelate with the metal ion in the active site. Distorting the geometry of these ligands could be the reason for the inhibition activity shown by tHGA. The molecular simulation studies supported the bioassay results and served as a good model for understanding the way tHGA binds in the active site of human 5-LOX enzyme.

Terpenoids and phenethyl glucosides from Hyssopus cuspidatus (Labiatae).

Monoterpenoids (3 and 4), sesquiterpenoid (2), diterpenoid (1) and four phenethyl glucosides (5-8), together with fourteen known compounds, were isolated from the whole herb of Hyssopus cuspidatus. Their structures were determined by spectroscopic means. The abietane-type diterpenoids (1, 9, 10), rosmarinic acid (15) and salvigenin (17) inhibited leukotriene (LT) C(4) secretion from primary alveolar cells of Wistar rats.

Prolonged culture of mast cells with high-glucose medium enhances the Fc epsilon RI-mediated degranulation response and leukotriene C4 production.

BACKGROUND: Mast cell-released chemical mediators such as histamine, leukotriene (LT) C(4) and prostaglandin (PG) D(2) lead to the onset of allergic disorders. ATP provided from glycolysis is essential for histamine release and LTC(4) secretion from mast cells upon Fc epsilon RI cross-linking, indicating that glucose is a primary environmental factor for mast cell activation. In this study, we investigated whether increases in concentrations of glucose in culture media affect the activation of bone marrow-derived mouse mast cells (BMMCs) upon Fc epsilon RI cross-linking. METHODS: BMMCs were cultured in RPMI-1640 supplemented with varying concentrations (5.5, 11, 16.5, 22, 27.5 and 33 mM) of D-glucose for 3 h, or 1, 3 or 7 days. D-Mannitol was added to the medium containing 5.5 mMD-glucose for osmotic control. After culturing, these cells were sensitized with anti-TNP IgE and then stimulated with TNP-BSA. RESULTS: We found that long-term culture (7 days) of BMMCs with 33 mMD-glucose increases the Fc epsilon RI-dependent release of beta-hexosaminidase and LTC(4) without affecting surface expression levels of Fc epsilon RI, intracellular ATP levels or calcium signaling. Biochemical analyses demonstrated that Fc epsilon RI-dependent phosphorylation of cytosolic phospholipase A(2) (cPLA(2)) at the Ser505 residue was significantly increased by culturing with 33 mM glucose. CONCLUSIONS: Taken together, our data suggest that glucose can augment Fc epsilon RI-mediated mast cell activation, particularly the degranulation response and LTC(4) secretion after prolonged culture of mast cells with high-glucose medium. Moreover, it is suggested that increased phosphorylation of cPLA(2) at the Ser505 residue contributes to the enhancement of LTC(4) secretion.

Anti-allergic activity of an ethanol extract from Salviae miltiorrhiza.

As part of an ongoing investigation aimed at the discovery of novel bioactive medicinal herbs with anti-inflammatory properties, the effects of an ethanolic extract from the parts of Salviae miltiorrhiza Bunge (ESM) were evaluated using in vitro and in vivo animal model analysis. ESM inhibited cyclooxygenase-2 (COX-2) and COX-1-dependent phases of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with IC50 values of 3.96 microg/mL and 21.54 microg/mL, respectively. Furthermore, ESM inhibited leukotriene C4 (LTC4) production with an IC50 value of 2.6 microg/mL. These results clearly demonstrated the dual COX-2 selective/5-lipoxygenase inhibitory activity that ESM possessed. ESM strongly inhibited a degranulation reaction in a dose dependent manner within a BMMC system, with an IC50 value of 22.4 microg/mL. Additionally, ESM was tested in a rat passive cutaneous anaphylaxis (PCA) reaction assay by oral administration (25 to 100 mg/kg). ESM dose-dependently inhibited the PCA reaction, which was activated by anti-dinirophenyl (DNP) IgE. These results suggested that ESM might be beneficial in regulating various allergic reactions.

Chemical constituents of Melandrium firmum Rohrbach and their anti-inflammatory activity.

In our ongoing search for anti-inflammatory agents originating from Korean medicinal plants, we found that the hexane and BuOH fractions of the MeOH extract from the whole plants of Melandrium firmum Rohrbach inhibited 5-lipoxygenase (5-LOX) activity. By activity-guided fractionation, eleven compounds, alpha-spinaterol (1), ursolic acid (2), ergosterol peroxide (3), alpha-spinaterol glucoside (4), 2-methoxy-9-beta-D-ribofuranosyl purine (5), aristeromycin (6), ecdysteron (7), polypodoaurein (8), (-)-bornesitol (9), mannitol (10) and cytisoside (11) were isolated from the hexane and BuOH fractions using column chromatography. Compounds 2, 5, 6, 8, 9, 10 and 11 were isolated for the first time from this plant. Compounds 1, 3, 4 and 7 inhibited 5-LOX activity with IC50 values of 21.04 microM, 42.30 microM, 32.82 microM, and 17.18 microM, respectively.

Antiinflammatory effects of Bu-zhong-yi-qi-tang in patients with perennial allergic rhinitis.

Bu-zhong-yi-qi-tang, an ancient formula of Chinese medicine usually used in the treatment of allergic diseases, was evaluated in the treatment of patients with perennial allergic rhinitis. In this study, 60 patients allergic to house dust mite allergen confirmed by skin test and MAST test were recruited and randomized. An experimental group of 36 patients was treated with Bu-zhong-yi-qi-tang, whereas a control group of 24 patients was treated with a non-effective formula Ping-wei-san for 3 months. The nasal symptomatic scores and the responses of polymorphonuclear neutrophils (PMN) to IL-4-stimulation were measured after treatment. The nasal symptomatic scores in the experimental group were significantly improved (3.78+/-0.09 before treatment vs. 0.57+/-0.06 after treatment). In contrast, no change was found in symptomatic scores in the control group (3.17+/-0.12 before treatment vs. 2.79+/-0.14 after treatment). Moreover, total serum IgE and the IL-4-stimulated production of PGE(2) and LTC(4) by PMN was significantly suppressed in the experimental group after treatment compared to the control group. The COX-2 mRNA expression in IL-4-stimulated PMN was also significantly suppressed after Bu-zhong-yi-qi-tang treatment. These results suggest that Bu-zhong-yi-qi-tang but not Ping-wei-san was beneficial to the patients with perennial allergic rhinitis via suppressed nasal inflammation by an antiinflammatory effect.

[Effects of among compositions of Herba Ephedrae decoction on genic xpression of 5-lipoxygenase activating protein, IL-4 and leukotriene C4 in asthmatic mice].

OBJECTIVE: To explore the regularity of recipe composition by observing inhibitory effects on the genic expression of 5-lipoxygenase activating protein, IL-4 and the leukotriene C4 in asthmatic mice. METHOD: The mice were challenged with OVA and administered ig with the Herba Ephedrae decoction (HED), separated compositions (2500 mg x kg(-1), calculated by Herba Ephedrae) and dexamethasone (2 mg x kg(-1)) respectively once daily for seven days. The real-time fluorescence quantitative PCR method was employed to measure the contents of FLAP mRNA and IL-4 mRNA expressions in lung and the ELISA method was used to determine the content of LTC4 in the washing solution of pulmonary alveolus and bronchi. RESULT: In the lung of asthma mice, the expressions of FLAP and IL-4 and the content of LTC4 were significantly augmented compared with the control group. The HED and the separated compositions could suppress the expressions of FLAP and IL-4 and LTC4 release to a great extent in mice. CONCLUSION: The HED had the remarkable effects of antianaphylaxis asthma and the original formula HED worked best. These results confirmed the rationality and scientific level of HED.

Anti-inflammatory principles from the fruits of Evodia rutaecarpa and their cellular action mechanisms.

The fruits of Evodia rutaecarpa Benth (Rutaceae) has long been used for inflammatory disorders and some anti-inflammatory actions of its constituents such as dehydroevodiamine, evodiamine and rutaecarpine were previously reported. Since the pharmacological data is not sufficient to clearly establish the scientific rationale of anti-inflammatory medicinal use of this plant material and the search for its active principles is limited so far, three major constituents (evodiamine, rutaecarpine, goshuyuamide II) were evaluated for their anti-inflammatory cellular action mechanisms in the present study. From the results, evodiamine and rutaecarpine were found to strongly inhibit prostaglandin E2 synthesis from lipopolysaccharide-treated RAW 264.7 cells at 1-10 microM. Evodiamine inhibited cyclooxygenase-2 induction and NF-kappaB activation, while rutaecarpine did not. On the other hand, goshuyuamide II inhibited 5-lipoxygenase from RBL-1 cells (IC50 = 6.6 microM), resulting in the reduced synthesis of leukotrienes. However, these three compounds were not inhibitory against inducible nitric oxide synthase-mediated nitric oxide production from RAW cells up to 50 micorM. These pharmacological properties may provide the additional scientific rationale for anti-inflammatory use of the fruits of E. rutaecarpa.

Systematic evaluation of transcellular activities of secretory phospholipases A2. High activity of group V phospholipases A2 to induce eicosanoid biosynthesis in neighboring inflammatory cells.

The mechanisms by which secretory phospholipase A2 (PLA2) exerts cellular effects are not fully understood. To elucidate these mechanisms, we systematically and quantitatively assessed the activities of human group IIA, V, and X PLA2s on originating and neighboring cells using orthogonal fluorogenic substrates in various mixed cell systems. When HEK293 cells stably expressing each of these PLA2s were mixed with non-transfected HEK293 cells, group V and X PLA2s showed strong transcellular lipolytic activity, whereas group IIA PLA2 exhibited much lower transcellular activity. The transcellular activity of group V PLA2 was highly dependent on the presence of cell surface heparan sulfate proteoglycans of acceptor cells. Activation of RBL-2H3 and DLD-1 cells that express endogenous group V PLA2 led to the secretion of group V PLA2 and its transcellular action on neighboring human neutrophils and eosinophils, respectively. Similarly, activation of human bronchial epithelial cells, BEAS-2B, caused large increases in arachidonic acid and leukotriene C4 release from neighboring human eosinophils. Collectively, these studies show that group V and X PLA2s can act transcellularly on mammalian cells and suggest that group V PLA2 released from neighboring cells may function in triggering the activation of inflammatory cells under physiological conditions.