Nepetin, a natural compound from Inulae flos, suppresses degranulation and eicosanoid generation through PLCγ1 and Akt signaling pathways in mast cells.

Nepetin derived from the flowers of Inula japonica, Inulae flos, has been reported to exert several biological activities, including anti-inflammatory responses. In this study, we evaluated the anti-allergic property of nepetin with its molecular mechanisms in bone marrow-derived mast cells (BMMC) and mice. In this in vitro study, we investigated the inhibitory effects of nepetin on degranulation and generation of leukotriene C4 (LTC4) and prostaglandin D2 (PGD2) in IgE/antigen (Ag)-stimulated BMMC. The effect of nepetin on passive cutaneous anaphylaxis (PCA) reaction was also studied in mice. Nepetin reduced degranulation and LTC4 generation in BMMC. The IgE/Ag-mediated signaling pathway demonstrated that nepetin suppressed intracellular Ca2+ level and activation of PLCγ1 and cPLA2. However, MAPKs were not affected by nepetin in BMMC. In addition, nepetin treatment reduced PGD2 production and suppressed cyclooxygenase-2 protein expression via the inhibition of the Akt and nuclear factor-κB signaling pathways. With respect to the local allergic response in vivo, oral administration of nepetin suppressed mast cell-dependent PCA reaction in a dose-dependent manner. The results of this study suggest that nepetin might have an anti-allergic potential related to mast cell-mediated inflammatory diseases.

Cysteinyl Leukotriene Receptor 2 is Involved in Inflammation and Neuronal Damage by Mediating Microglia M1/M2 Polarization through NF-κB Pathway.

Microglia activation plays a key role in regulating inflammatory and immune reaction during cerebral ischemia and it exerts pro-inflammatory or anti-inflammatory effect depending on M1/M2 polarization phenotype. Cysteinyl leukotriene 2 receptor (CysLT2R) is a potent inflammatory mediator receptor, and involved in cerebral ischemic injury, but the mechanism of CysLT2R regulating inflammation and neuron damage remains unclear. Here, we found that LPS and CysLT2R agonist NMLTC4 significantly increased microglia proliferation and phagocytosis, up-regulated the mRNA expression of M1 polarization markers (IL-1ß, TNF-α, IFN-γ, CD86 and iNOS), down-regulated the expression of M2 polarization markers (Arg-1, CD206, TGF-ß, IL-10, Ym-1) and increased the release of IL-1ß and TNF-α. CysLT2R selective antagonist HAMI3379 could antagonize these effects. IL-4 significantly up-regulated the mRNA expression of M2 polarization markers, and HAMI3379 further increased IL-4-induced up-regulation of M2 polarization markers expression. Additionally, LPS and NMLTC4 stimulated NF-κB p50 and p65 proteins expression, and promoted p50 transfer to the nucleus. Pre-treatment with HAMI3379 and NF-κB signaling inhibitor Bay 11-7082 could reverse the up-regulation of p50 and p65 proteins expression, and inhibited p50 transfer to the nucleus. The conditional medium of BV-2 cells contained HAMI3379 could inhibit SH-SY5Y cells apoptosis induced by LPS and NMLTC4. These results were further confirmed in primary microglia. The findings indicate that CysLT2R was involved in inflammation and neuronal damage by inducing the activation of microglia M1 polarization and NF-κB pathway, inhibiting microglia M1 polarization and promoting microglia polarization toward M2 phenotype which may exerts neuroprotective effects, and targeting CysLT2R may be a new therapeutic strategy against cerebral ischemia stroke.

Seongsanamides A-D: Antiallergic Bicyclic Peptides from Bacillus safensis KCTC 12796BP.

Six seongsanamides were isolated from the culture broth of Bacillus safensis KCTC 12796BP, and their structures were elucidated by spectroscopic data analysis combined with Marfey's method, electronic circular dichroism calculations, and biosynthetic gene cluster analysis. Compounds 1-4 were bicyclic peptides with isodityrosine residues; 5 and 6 were monocyclic peptides. Only the bicyclic seongsanamides inhibited degranulation and LTC4/PGD2 generation in IgE/Ag-stimulated bone marrow-derived mast cells. Oral administration of 1 suppressed mast cell-dependent passive cutaneous anaphylaxis reaction.

Leukotrienes and kidney diseases.

PURPOSE OF REVIEW: This review will critically highlight the role of leukotrienes as mediators of renal diseases and drug nephrotoxicity. It will also discuss the recently identified mechanism of cysteinyl leukotrienes induction and action, and will propose clinical implementation of these findings. RECENT FINDINGS: Since last reviewed in 1994, leukotrienes were shown to mediate drug-associated nephrotoxicity, transplant rejection and morbidity in several models of renal diseases. Although leukotrienes may be released by various infiltrating leukocytes, a recent study demonstrated that cytotoxic agents trigger production of leukotriene C4 (LTC4) in mouse kidney cells by activating a biosynthetic pathway based on microsomal glutathione-S-transferase 2 (MGST2). LTC4 then elicits nuclear accumulation of hydrogen peroxide-generating NADPH oxidase 4, leading to oxidative DNA damage and cell death. LTC4 inhibitors, commonly used as systemic asthma drugs, alleviated drug-associated damage to proximal tubular cells and attenuated mouse morbidity. SUMMARY: Cysteinyl leukotrienes released by mast cells trigger the symptoms of asthma, including bronchoconstriction and vasoconstriction. Therefore, effective leukotriene inhibitors were approved as orally administered asthma drugs. The findings that leukotrienes mediate the cytotoxicity of nephrotoxic drugs, and are involved in numerous renal diseases, suggest that such asthma drugs may ameliorate drug-induced nephrotoxicity, as well as some renal diseases.

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.

Leukotriene C4 induces bronchoconstriction and airway vascular hyperpermeability via the cysteinyl leukotriene receptor 2 in S-hexyl glutathione-treated guinea pigs.

Cysteinyl leukotrienes act through G-protein-coupled receptors termed cysteinyl leukotriene 1 (CysLT1) and cysteinyl leukotriene 2 (CysLT2) receptors. However, little is known about the pathophysiological role of CysLT2 receptors in asthma. To elucidate the possible involvement of CysLT2 receptors in bronchoconstriction and airway vascular hyperpermeability, we have established a novel guinea pig model of asthma. In vitro study confirmed that CHO-K1 cells, expressing guinea pig CysLT2 and CysLT1 receptors are selectively stimulated by LTC4 and LTD4, respectively. However, when LTC4 was intravenously injected to guinea pigs, the resulting bronchoconstriction was fully abrogated by montelukast, a CysLT1 receptor antagonist, indicating rapid metabolism of LTC4 to LTD4 in the lung. We found that treatment with S-hexyl glutathione (S-hexyl GSH), an inhibitor of gamma-glutamyl transpeptidase, significantly increased LTC4 content and LTC4/(LTD4 plus LTE4) ratio in the lung. Under these circumstances, LTC4-induced bronchoconstriction became resistant to montelukast, but sensitive to Compound A, a CysLT2 receptor antagonist, depending on the dose of S-hexyl GSH. Combination with montelukast and Compound A completely abrogated this spasmogenic response. Additionally, we confirmed that LTC4 elicits airway vascular hyperpermeability via CysLT2 receptors in the presence of high dose of S-hexyl GSH as evidenced by complete inhibition of LTC4-induced hyperpermeability by Compound A, but not montelukast. These results suggest that CysLT2 receptors mediate bronchoconstriction and airway vascular hyperpermeability in guinea pigs and that the animal model used in this study may be useful to elucidate the functional role of CysLT2 receptors in various diseases, including asthma.

The influence of leukotrienes C4 and D4 on the contractility of an inflamed porcine uterus.

The effect of leukotriene (LT) C4 (LTC4) and LTD4 on the contractility of an inflamed porcine uterus was investigated. On Day 3 of the estrous cycle (Day 0 of the study), either saline or Escherichia coli suspension was injected into each uterine horn. Although acute endometritis developed in all bacteria-inoculated gilts, a severe acute endometritis was noted more often on Day 8 than on Day 16. Myometrial and endometrial/myometrial strips were incubated with LTC4 or LTD4 alone, or together with a cysteinyl-LT receptor antagonist (BAY-u9773). Leukotriene C4 increased the contraction intensity in the saline- and bacteria-treated uteri on Day 8; however, its effect was lower in the myometrium of inflamed uteri. Contraction frequency was found to decrease in the saline-treated uteri as opposed to inflamed ones, in which it was elevated. On Day 16, contraction intensity increased in response to LTC4 in the saline-treated uteri but was reduced in the inflamed organs. The value of this parameter was lower in the inflamed uteri than that in the saline-treated ones. Leukotriene D4 (Days 8 and 16) augmented contractility in the saline-treated uteri, but despite increasing its intensity in the inflamed organs, it decreased contraction frequency. Leukotriene C4 or LTD4, added to BAY-u9773-pretreated saline- and bacteria-treated uteri on both days, decreased the contraction intensity. On Day 16 after treatment with BAY-u9773 and LTC4, contraction intensity in the endometrium/myometrium of the inflamed uteri was lower than that in the saline-treated organs. Data show that both LTC4 and LTD4 affect the contractility of inflamed porcine uteri, though LTC4 exerts a weaker contractile effect.

Modulation of basophils' degranulation and allergy-related enzymes by monomeric and dimeric naphthoquinones.

Allergic disorders are characterized by an abnormal immune response towards non-infectious substances, being associated with life quality reduction and potential life-threatening reactions. The increasing prevalence of allergic disorders demands for new and effective anti-allergic treatments. Here we test the anti-allergic potential of monomeric (juglone, menadione, naphthazarin, plumbagin) and dimeric (diospyrin and diosquinone) naphthoquinones. Inhibition of RBL-2H3 rat basophils' degranulation by naphthoquinones was assessed using two complementary stimuli: IgE/antigen and calcium ionophore A23187. Additionally, we tested for the inhibition of leukotrienes production in IgE/antigen-stimulated cells, and studied hyaluronidase and lipoxidase inhibition by naphthoquinones in cell-free assays. Naphthazarin (0.1 µM) decreased degranulation induced by IgE/antigen but not A23187, suggesting a mechanism upstream of the calcium increase, unlike diospyrin (10 µM) that reduced degranulation in A23187-stimulated cells. Naphthoquinones were weak hyaluronidase inhibitors, but all inhibited soybean lipoxidase with the most lipophilic diospyrin, diosquinone and menadione being the most potent, thus suggesting a mechanism of competition with natural lipophilic substrates. Menadione was the only naphthoquinone reducing leukotriene C4 production, with a maximal effect at 5 µM. This work expands the current knowledge on the biological properties of naphthoquinones, highlighting naphthazarin, diospyrin and menadione as potential lead compounds for structural modification in the process of improving and developing novel anti-allergic drugs.

Novel polyhydroxylated steroids from the East China Sea gorgonian Echinogorgia sassapo reticulata with suppressive activity of leukotriene C4 generation and degranulation in bone marrow-derived mast cells.

The gorgonian Echinogorgia sassapo reticulata contains two new bioactive polyhydroxylated steroids, sassapols A (1), B (2), and five related known compounds (3-7). Compound 6 has been encountered for the first time in natural sources. The structures of these new compounds were defined by spectroscopic analysis. All the compounds (1-7) isolated from E. sassapo reticulata were tested for anti-inflammatory activity. Compounds 1, 3, 5, and 7 inhibited both the generation of leukotriene C4 and the degranulation reaction in mouse bone marrow-derived mast cells.

Low temperature inhibits pollen tube growth by disruption of both tip-localized reactive oxygen species and endocytosis in Pyrus bretschneideri Rehd.

Low temperature (LT) negatively affects fertilization processes of flowering plants. Pollen tube growth is generally inhibited under LT stress; however, the mechanism(s) underlying this inhibition remain(s) largely unknown. Pollen tubes are tip-growing and the presence of tip-localized reactive oxygen species (ROS) is necessary for cellular functioning. Disruption of tip-localized ROS was observed in pear pollen tubes in vitro under low temperature of 4 °C (LT4). Diphenylene iodonium chloride, an NADPH oxidase (NOX) inhibitor, suppressed hydrogen peroxide formation in the cell walls of the subapical region in pear pollen tubes. Under LT4 stress, ROS disruption in pear pollen tubes mainly resulted from decreased NOX activity in the plasma membrane, indicating that NOX was the main source of ROS in this process. Moreover, LT4 remarkably decreased mitochondrial oxygen consumption and intracellular ATP production. The endocytosis, an energy-dependent process, disruption in pear pollen tubes under LT4 may be mediated by mitochondrial metabolic dysfunctions. Our data showed ROS and endocytosis events in pear pollen tubes responding to LT4 stress.

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

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

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.

Luteolin-7-O-glucoside suppresses leukotriene C(4) production and degranulation by inhibiting the phosphorylation of mitogen activated protein kinases and phospholipase Cγ1 in activated mouse bone marrow-derived mast cells.

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

Leukotriene biosynthesis inhibition ameliorates acute lung injury following hemorrhagic shock in rats.

BACKGROUND: Hemorrhagic shock followed by resuscitation is conceived as an insult frequently induces a systemic inflammatory response syndrome and oxidative stress that results in multiple-organ dysfunction syndrome including acute lung injury. MK-886 is a leukotriene biosynthesis inhibitor exerts an anti inflammatory and antioxidant activity. OBJECTIVES: The objective of present study was to assess the possible protective effect of MK-886 against hemorrhagic shock-induced acute lung injury via interfering with inflammatory and oxidative pathways. MATERIALS AND METHODS: Eighteen adult Albino rats were assigned to three groups each containing six rats: group I, sham group, rats underwent all surgical instrumentation but neither hemorrhagic shock nor resuscitation was done; group II, Rats underwent hemorrhagic shock (HS) for 1 hr then resuscitated with Ringer's lactate (1 hr) (induced untreated group, HS); group III, HS + MK-886 (0.6 mg/kg i.p. injection 30 min before the induction of HS, and the same dose was repeated just before reperfusion period). At the end of experiment (2 hr after completion of resuscitation), blood samples were collected for measurement of serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The trachea was then isolated and bronchoalveolar lavage fluid (BALF) was carried out for measurement of leukotriene B4 (LTB4), leukotriene C4 (LTC4) and total protein. The lungs were harvested, excised and the left lung was homogenized for measurement of malondialdehyde (MDA) and reduced glutathione (GSH) and the right lung was fixed in 10% formalin for histological examination. RESULTS: MK-886 treatment significantly reduced the total lung injury score compared with the HS group (P < 0.05). MK-886 also significantly decreased serum TNF-α & IL-6; lung MDA; BALF LTB4, LTC4 & total protein compared with the HS group (P < 0.05). MK-886 treatment significantly prevented the decrease in the lung GSH levels compared with the HS group (P < 0.05). CONCLUSIONS: The results of the present study reveal that MK-886 may ameliorate lung injury in shocked rats via interfering with inflammatory and oxidative pathways implicating the role of leukotrienes in the pathogenesis of hemorrhagic shock-induced lung inflammation.

Conjunctival goblet cell secretion stimulated by leukotrienes is reduced by resolvins D1 and E1 to promote resolution of inflammation.

The conjunctiva is a mucous membrane that covers the sclera and lines the inside of the eyelids. Throughout the conjunctiva are goblet cells that secrete mucins to protect the eye. Chronic inflammatory diseases such as allergic conjunctivitis and early dry eye lead to increased goblet cell mucin secretion into tears and ocular surface disease. The purpose of this study was to determine the actions of the inflammatory mediators, the leukotrienes and the proresolution resolvins, on secretion from cultured rat and human conjunctival goblet cells. We found that both cysteinyl leukotriene (CysLT) receptors, CysLT(1) and CysLT(2,) were present in rat conjunctiva and in rat and human cultured conjunctival goblet cells. All leukotrienes LTB(4), LTC(4), LTD(4), and LTE(4), as well as PGD(2), stimulated goblet cell secretion in rat goblet cells. LTD(4) and LTE(4) increased the intracellular Ca(2+) concentration ([Ca(2+)](i)), and LTD(4) activated ERK1/2. The CysLT(1) receptor antagonist MK571 significantly decreased LTD(4)-stimulated rat goblet cell secretion and the increase in [Ca(2+)](i). Resolvins D1 (RvD1) and E1 (RvE1) completely reduced LTD(4)-stimulated goblet cell secretion in cultured rat goblet cells. LTD(4)-induced secretion from human goblet cells was blocked by RvD1. RvD1 and RvE1 prevented LTD(4)- and LTE(4)-stimulated increases in [Ca(2+)](i), as well as LTD(4) activation of ERK1/2. We conclude that cysteinyl leukotrienes stimulate conjunctival goblet cell mucous secretion with LTD(4) using the CysLT(1) receptor. Stimulated secretion is terminated by preventing the increase in [Ca(2+)](i) and activation of ERK1/2 by RvD1 and RvE1.

Mechanisms for anti-inflammatory effects of 1-[15(S)-hydroxyeicosapentaenoyl] lysophosphatidylcholine, administered intraperitoneally, in zymosan A-induced peritonitis.

BACKGROUND AND PURPOSE: Lysophosphatidylcholines (lysoPCs) with polyunsaturated acyl chains are known to exert anti-inflammatory actions. 15-Lipoxygeanation is crucial for anti-inflammatory action of polyunsaturated acylated lysoPCs. Here, the anti-inflammatory actions of 1-(15-hydroxyeicosapentaenoyl)-lysoPC (15-HEPE-lysoPC) and its derivatives were examined in a mechanistic analysis. EXPERIMENTAL APPROACH: Anti-inflammatory actions of 15-HEPE-lysoPC in zymosan A-induced peritonitis of mice were examined by measuring plasma leakage and leucocyte infiltration, and determining levels of lipid mediators or cytokines. KEY RESULTS: When each lysoPC, administered i.v., was assessed for its ability to suppress zymosan A-induced plasma leakage, 15-HEPE-lysoPC was found to be more potent than 1-(15-hydroperoxyeicosapentaenoyl)-lysoPC or 1-eicosapentaenoyl-lysoPC. Separately, i.p. administration of 15-HEPE-lysoPC markedly inhibited plasma leakage, in contrast to 15-HEPE, which had only a small effect. 15-HEPE-lysoPC also decreased leucocyte infiltration. Moreover, it reduced the formation of LTC4 and LTB4, 5-lipoxygenation products, as well as the levels of pro-inflammatory cytokines. The time-course study indicated that 15-HEPE-lysoPC might participate in both the early inflammatory phase and resolution phase. Additionally, 15-HEPE-lysoPC administration caused a partial suppression of LTC4-induced plasma leakage and LTB4-induced leucocyte infiltration. In the metabolism study, peritoneal exudate was shown to contain lysoPC-hydrolysing activity, crucial for anti-inflammatory activity, and a system capable of generating lipoxin A from 15-hydroxy eicosanoid precursor. CONCLUSIONS AND IMPLICATIONS: 15-HEPE-lysoPC, a precursor for 15-HEPE in target cells, induced anti-inflammatory actions by inhibiting the formation of pro-inflammatory leukotrienes and cytokines, and by enhancing the formation of lipoxin A. 15-HEPE-lysoPC might be one of many potent anti-inflammatory lipids in vivo.

Anti-allergic effects of sinomenine by inhibition of prostaglandin D2 and leukotriene C4 in mouse bone marrow-derived mast cells.

Sinomenine is an alkaloid compound and a prominent anti-allergic agent found in the root of the climbing plant Sinomenium acutum. However, its effects on the bone marrow-derived mast cell (BMMC) mediated allergy and inflammation mechanism remain unknown. In this study, the biological effects of sinomenine were evaluated while focusing on its effects on the allergic mediator in PMA plus A23187-stimulated BMMCs. An investigation was also conducted to determine its effects on the production of several allergic mediators including interleukin-6 (IL-6), prostaglandin D(2) (PGD(2)), leukotriene C(4) (LTC(4)), ß-Hexosaminidase (ß-Hex), and cyclooxygenase-2 (COX-2) protein. The results revealed that sinomenine inhibited the PMA plus A23187-induced production of IL-6, PGD(2), LTC(4), ß-Hex, and COX-2 protein. Taken together, these findings indicate that sinomenine has the potential for use in the treatment of allergy.

Inhibition of leukotriene C4 action reduces oxidative stress and apoptosis in cardiomyocytes and impedes remodeling after myocardial injury.

UNLABELLED: Tissue damage leads to release of pro-inflammatory mediators. Among these, leukotriene C(4) (LTC(4)) is a powerful, intracellularly induced mediator of inflammation, which requires inside-out transport of LTC(4). We investigated whether release of LTC(4)via the multidrug resistance related protein 1 (MRP1) induces apoptosis in cardiomyocytes in vitro and in vivo. METHODS AND RESULTS: Incubation of cultured embryonic cardiomyocytes (eCM) with recombined LTC(4) caused enhanced rates of reactive oxygen species (ROS) release measured via L012-luminescence method and apoptosis. Pharmacologic LTC(4) receptor blockade antagonized this effect in vitro. To evaluate the relevance of MRP1 mediated LTC(4) release after myocardial injury in vivo, MRP1(-/-) mice and FVB wildtype mice (WT) received cryoinjury of the left ventricle. Fourteen days after injury, left-ventricular ejection fraction (EF), end-diastolic volume (EDV), and akinetic myocardial mass (AMM) were quantified via echocardiography. MRP1(-/-) mice demonstrated increased EF (MRP1(-/-): 39 ± 3%, WT: 29 ± 4%) and reduced AMM (MRP1(-/-): 13 ± 2% WT: 16 ± 4%), indicating reduced post-infarction remodeling. Mechanistically, LTC(4) serum concentrations and levels of cellular apoptosis were increased in myocardial cryosections of FVB WT mice as compared to MRP1(-/-) mice. To identify key targets for pharmacological inhibition of LTC(4) actions, WT mice were treated with the specific Cys-LT1-receptor blocker Montelukast or the MRP1-Inhibitor MK571. Treatment of WT mice resulted in significant increase of EF (WT(Montelukast): 40 ± 5%, WT(MK571): 39 ± 3%, WT(vehicle): 33 ± 3% and decrease of AMM (WT(Montelukast): 12 ± 1%, WT(MK571): 10 ± 3%, WT(vehicle): 15 ± 5%) compared to untreated WT mice. CONCLUSION: Inhibition of leukotriene C(4) reduces levels of oxidative stress and apoptosis and demonstrates beneficial effects on myocardial remodeling after left ventricular injury.

Leukotrienes modulate secretion of progesterone and prostaglandins during the estrous cycle and early pregnancy in cattle: an in vivo study.

Recently, we showed that leukotrienes (LTs) regulate ovarian cell function in vitro. The aim of this study was to examine the role of LTs in corpus luteum (CL) function during both the estrous cycle and early pregnancy in vivo. mRNA expression of LT receptors (BLT for LTB(4) and CYSLT for LTC(4)), and 5-lipoxygenase (5-LO) in CL tissue and their localization in the ovary were studied during the estrous cycle and early pregnancy. Moreover, concentrations of LTs (LTB(4) and C(4)) in the CL tissue and blood were measured. 5-LO and BLT mRNA expression increased on days 16-18 of the cycle, whereas CYSLT mRNA expression increased on days 16-18 of the pregnancy. The level of LTB(4) was evaluated during pregnancy compared with the level of LTC(4), which increased during CL regression. LT antagonists influenced the duration of the estrous cycle: the LTC(4) antagonist (azelastine) prolonged the luteal phase, whereas the LTB(4) antagonist (dapsone) caused earlier luteolysis in vivo. Dapsone decreased progesterone (P(4)) secretion and azelastine increased P(4) secretion during the estrous cycle. In summary, LT action in the bovine reproductive tract is dependent on LT type: LTB(4) is luteotropic during the estrous cycle and supports early pregnancy, whereas LTC(4) is luteolytic, regarded as undesirable in early pregnancy. LTs are produced/secreted in the CL tissue, influence prostaglandin function, and serve as important factors during the estrous cycle and early pregnancy in cattle.

Epigallocatechin-3-gallate inhibits mast cell degranulation, leukotriene C4 secretion, and calcium influx via mitochondrial calcium dysfunction.

The green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) has been shown to reduce allergic inflammatory responses in animal models, but the mechanisms involved are poorly understood. Despite the essential role for Ca(2+) influx in mediating proinflammatory mediator release from mast cells, little is known about the effects of EGCG on this response. In the present study we found that EGCG inhibited antigen-induced Ca(2+) influx and store-operated Ca(2+) entry (SOCE), the principal mode of Ca(2+) influx into mast cells. EGCG, but not (-)-epicatechin (EC), inhibited antigen-induced degranulation, leukotriene (LT) C(4) secretion, and Ca(2+) influx. EGCG also blocked SOCE without reducing Ca(2+) store emptying whereas EC did not, although it did reduce Ca(2+) store emptying. EGCG, but not EC, also evoked intracellular reactive oxygen species (ROS) production, mitochondrial membrane potential (Psi(m)) collapse, cardiolipin oxidation, and mitochondrial Ca(2+) ([Ca(2+)](m)) release. Furthermore, FCCP, a potent inducer of Psi(m) collapse, induced ROS production and [Ca(2+)](m) dysfunction and inhibited degranulation, LTC(4) secretion, Ca(2+) influx, and SOCE. These data suggest that ROS production and Psi(m) collapse are important mechanisms underlying the antiallergic effects of EGCG. These events may lead to [Ca(2+)](m) dysfunction and impair mitochondria-mediated facilitation of SOCE, thereby attenuating mast cell activation.