Protective activities of distinct omega-3 enriched oils are linked to their ability to upregulate specialized pro-resolving mediators.

Clinical studies using a range of omega-3 supplements have yielded conflicting results on their efficacy to control inflammation. Omega-3 fatty acids are substrate for the formation of potent immune-protective mediators, termed as specialized pro-resolving mediators (SPM). Herein, we investigated whether observed differences in the potencies of distinct omega-3 supplements were linked with their ability to upregulate SPM formation. Using lipid mediator profiling we found that four commercially available supplements conferred a unique SPM signature profile to human macrophages, with the overall increases in SPM concentrations being different between the four supplements. These increases in SPM concentrations were linked with an upregulation of macrophage phagocytosis and a decreased uptake of oxidized low-density lipoproteins. Pharmacological inhibition of two key SPM biosynthetic enzymes 5-Lipoxygenase or 15-Lipoxygenase reversed the macrophage-directed actions of each of the omega-3 supplements. Furthermore, administration of the two supplements that most potently upregulated macrophage SPM formation and reprogrammed their responses in vitro, to APOE-/- mice fed a western diet, increased plasma SPM concentrations and reduced vascular inflammation. Together these findings support the utility of SPM as potential prognostic markers in determining the utility of a given supplement to regulate macrophage responses and inflammation.

A combination of LCPUFA ameliorates airway inflammation in asthmatic mice by promoting pro-resolving effects and reducing adverse effects of EPA.

Lipid mediators derived from omega (n)-3 and n-6 long-chain polyunsaturated fatty acids (LCPUFA) play key roles in bronchoconstriction, airway inflammation, and resolution processes in asthma. This study compared the effects of dietary supplementation with either a combination of LCPUFAs or eicosapentaenoic acid (EPA) alone to investigate whether the combination has superior beneficial effects on the outcome of asthmatic mice. Mice were sensitized with house dust mite (HDM) extract, and subsequently supplemented with either a combination of LCPUFAs or EPA alone in a recall asthma model. After the final HDM and LCPUFA administration, airway hyperresponsiveness (AHR), bronchoalveolar lavages, and lung histochemistry were examined. Lipid mediator profiles were determined by liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS). The LCPUFA combination reduced AHR, eosinophilic inflammation, and inflammatory cytokines (IL-5, IFN-γ, and IL-6) in asthmatic mice, whereas EPA enhanced inflammation. The combination of LCPUFAs was more potent in downregulating EPA-derived LTB5 and LTC5 and in supporting DHA-derived RvD1 and RvD4 (2.22-fold and 2.58-fold higher levels) than EPA alone. Ex vivo experiments showed that LTB5 contributes to granulocytes' migration and M1-polarization in monocytes. Consequently, the LCPUFA combination ameliorated airway inflammation by inhibiting adverse effects of EPA and promoting pro-resolving effects supporting the lipid mediator-dependent resolution program.

Effects of anti-inflammatory and adaptogenic herbal extracts on gene expression of eicosanoids signaling pathways in isolated brain cells.

INTRODUCTION: The adaptogens modulate expression of genes playing key roles in development of aging-related disorders, which are considered as low-grade systemic inflammatory conditions characterized by an imbalance between pro-and anti-inflammatory eicosanoids. AIM OF THE STUDY: We compared the effects of anti-inflammatory and adaptogenic plant extracts on the expression of genes involved in biosynthesis of eicosanoids with the purpose to find those plants, which selectively upregulated the expression of anti-inflammatory lipoxins signaling pathways and inhibited pro-inflammatory signaling pathways associated with biosynthesis of leukotrienes, prostaglandins and thromboxanes. MATERIALS AND METHODS: We conducted transcriptome-wide RNA sequencing to profile gene expression alterations in T98G neuroglia cells upon treatment of plant extract and analyzed the relevance of deregulated genes to eicosanoids signaling pathways using in silico models. RESULTS: For the first time, we demonstrated that Rhodiola rosea, Withania somnifera and Eleutherococcus senticosus downregulate the expression of key genes (ALOX5AP, DPEP2, LTC4S) involved biosynthesis of leukotrienes A, B, C, D and E, resulting in inhibition of leukotriene signaling pathway suggesting their potential benefits in Alzheimer disease. The common feature for all tested anti-inflammatory plants extracts was related to downregulation of ALOX12, which was also associated with neuroprotective action of these medicinal plants as well as their potential benefits in neurodegenerative diseases. None of tested anti-inflammatory and adaptogenic plants selectively activated the ALOX15-mediated signaling pathway, which is associated with generation anti-inflammatory lipoxins. Almost all tested plants upregulated the expression of the prostaglandin E receptor 3 gene (PTGER3) suggesting their potential benefits in the treatment of cancer. CONCLUSION: Every single plant tested in this study revealed a specific "signature" on eicosanoid signaling-related gene expression, regardless of their common features as anti-inflammatory or adaptogenic activity. Further studies of the combination of Rhodiola with Withania (Adaptra) for the treatment of Alzheimer disease are required.

Production of lipid mediators across different disease stages of dextran sodium sulfate-induced colitis in mice.

Although several studies have revealed the role of different lipid mediators in colitis, the comprehensive analysis of their production across different phases of colitis remained unclear. Here, we performed the following analysis in the dextran sodium sulfate (DSS)-induced colitis model using LC-MS/MS. Oral administration of 2% DSS in mice for 4 days resulted in severe intestinal inflammation by day 7, which gradually subsided by day 18. Based on the disease scoring index (assigned on the basis of fecal condition and weight loss), we defined the phases of colitis as induction (days 0-4), acute inflammation (days 4-7), recovery (days 7-9), and late recovery (days 9-18). Across all phases, 58 lipid mediators were detected in the inflamed colon tissue. In the induction phase, the production of n-6 fatty acid-derived prostaglandin E2 and thromboxane B2 increased by ∼2-fold. In the acute inflammation phase, the production of n-6 fatty acid-derived leukotrienes increased by >10-fold, while that of n-3 fatty acid-derived hydroxyeicosapentaenoic acids and dihydroxyeicosatetraenoic acids decreased. In the recovery phase, a precursor of protectin D1 (17-hydroxydocosahexaenoic acid) increased over 3-fold. These observations suggested dynamic changes in the production of lipid mediators across different phases of the disease and their potential regulation in healing colitis.

Androgen-mediated sex bias impairs efficiency of leukotriene biosynthesis inhibitors in males.

Proinflammatory leukotrienes (LTs) are produced by 5-lipoxygenase (5-LO) aided by 5-LO-activating protein (FLAP). LT biosynthesis inhibitors are currently under clinical investigation as treatments for respiratory and cardiovascular diseases. Here, we have revealed a sex bias in the efficiency of clinically relevant LT biosynthesis inhibitors, showing that their effects are superior in females. We found that androgens cause these sex differences by impeding the LT-biosynthetic 5-LO/FLAP complex assembly. Lower doses of the FLAP inhibitor MK886 were required to reduce LTB4 levels in exudates of female versus male mice and rats. Following platelet-activating factor-induced shock, MK886 increased survival exclusively in female mice, and this effect was abolished by testosterone administration. FLAP inhibitors and the novel-type 5-LO inhibitors licofelone and sulindac sulfide exhibited higher potencies in human blood from females, and bioactive 5-LO/FLAP complexes were formed in female, but not male, human and murine leukocytes. Supplementation of female blood or leukocytes with 5α-dihydrotestosterone abolished the observed sex differences. Our data suggest that females may benefit from anti-LT therapy to a greater extent than males, prompting consideration of sex issues in LT modifier development.

Multitargeted Imidazoles: Potential Therapeutic Leads for Alzheimer's and Other Neurodegenerative Diseases.

Alzheimer's disease (AD) is a complex, multifactorial disease in which different neuropathological mechanisms are likely involved, including those associated with pathological tau and Aß species as well as neuroinflammation. In this context, the development of single multitargeted therapeutics directed against two or more disease mechanisms could be advantageous. Starting from a series of 1,5-diarylimidazoles with microtubule (MT)-stabilizing activity and structural similarities with known NSAIDs, we conducted structure-activity relationship studies that led to the identification of multitargeted prototypes with activities as MT-stabilizing agents and/or inhibitors of the cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) pathways. Several examples are brain-penetrant and exhibit balanced multitargeted in vitro activity in the low µM range. As brain-penetrant MT-stabilizing agents have proven effective against tau-mediated neurodegeneration in animal models, and because COX- and 5-LOX-derived eicosanoids are thought to contribute to Aß plaque deposition, these 1,5-diarylimidazoles provide tools to explore novel multitargeted strategies for AD and other neurodegenerative diseases.

Discovery of the first dual inhibitor of the 5-lipoxygenase-activating protein and soluble epoxide hydrolase using pharmacophore-based virtual screening.

Leukotrienes (LTs) are pro-inflammatory lipid mediators derived from arachidonic acid (AA) with roles in inflammatory and allergic diseases. The biosynthesis of LTs is initiated by transfer of AA via the 5-lipoxygenase-activating protein (FLAP) to 5-lipoxygenase (5-LO). FLAP inhibition abolishes LT formation exerting anti-inflammatory effects. The soluble epoxide hydrolase (sEH) converts AA-derived anti-inflammatory epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatetraenoic acids (di-HETEs). Its inhibition consequently also counteracts inflammation. Targeting both LT biosynthesis and the conversion of EETs with a dual inhibitor of FLAP and sEH may represent a novel, powerful anti-inflammatory strategy. We present a pharmacophore-based virtual screening campaign that led to 20 hit compounds of which 4 targeted FLAP and 4 were sEH inhibitors. Among them, the first dual inhibitor for sEH and FLAP was identified, N-[4-(benzothiazol-2-ylmethoxy)-2-methylphenyl]-N'-(3,4-dichlorophenyl)urea with IC50 values of 200 nM in a cell-based FLAP test system and 20 nM for sEH activity in a cell-free assay.

Are basophil activation and sulphidoleukotriene determination useful tests for monitoring patients with peach allergy receiving sublingual immunotherapy with a Pru p 3-enriched peach extract?

INTRODUCTION: Treatment of food allergy essentially consists of food avoidance, but immunotherapy with food is emerging as a new therapeutic option. OBJECTIVE: To evaluate clinical improvement and immunological changes in patients with peach allergy following sublingual immunotherapy (SLIT) with a Prup3 quantified peach extract. METHODS: A randomized, double-blind, placebo-controlled clinical trial with peach SLIT was conducted. We assessed clinical efficacy after 6 months of treatment by means of double-blind, placebo-controlled oral challenges with peach and also evaluated immunological changes (basophil activation test [BAT] and determination of sulphidoleukotriene production) following stimulation with peach peel and pulp, rPrup3, rMald 1, and rMal d 4 stimulation. We also measured specific IgE and IgG4 to Pru p3. RESULTS: After 6 months of SLIT (T6), the active group showed a 3-fold improvement in tolerance to Prup3 and a significant increase in IgE to rPrup3 and in sLT production following stimulation with peach peel and rPrup3. There was also a significant increase in BAT results after stimulation with rPrup3 at 1 month of SLIT (T1). Statistically significant between-group differences were only observed for BAT with peach peel and pulp at T1 and T6 and for BAT with rPru p3 at T6. No changes were observed in BAT with rMal d 1 or rMal d 4 or in IgG4 levels to nPrup3. CONCLUSIONS: SLIT with a Pru p 3 quantified peach extract is clinically effective and leads to an increase in basophil activation and sulphidoleukotriene production following stimulation with rPru p3 and peach peel in the first months of treatment.

Impact of botanical oils on polyunsaturated fatty acid metabolism and leukotriene generation in mild asthmatics.

BACKGROUND: Dietary supplementation with botanical oils that contain n-6 and n-3 eighteen carbon chain (18C)-PUFA such as γ linolenic acid (GLA, 18:3n-6), stearidonic acid (SDA, 18:4n-3) and α linolenic acid (ALA, 18:3n-3) have been shown to impact PUFA metabolism, alter inflammatory processes including arachidonic acid (AA) metabolism and improve inflammatory disorders. METHODS: The diet of mild asthmatics patients was supplemented for three weeks with varying doses of two botanical seed oils (borage oil [Borago officinalis, BO] and echium seed oil [Echium plantagineum; EO]) that contain SDA, ALA and GLA. A three week wash out period followed. The impact of these dietary manipulations was evaluated for several biochemical endpoints, including in vivo PUFA metabolism and ex vivo leukotriene generation from stimulated leukocytes. RESULTS: Supplementation with several EO/BO combinations increased circulating 20-22 carbon (20-22C) PUFAs, including eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and dihommo-gammalinolenic acid (DGLA), which have been shown to inhibit AA metabolism and inflammation without impacting circulating AA levels. BO/EO combinations also inhibited ex vivo leukotriene generation with some combinations attenuating cysteinyl leukotriene generation in stimulated basophils by >50% and in stimulated neutrophils by >35%. CONCLUSIONS: This study shows that dietary supplementation with BO/EO alters 20-22C PUFA levels and attenuates leukotriene production in a manner consistent with a reduction in inflammation.

Cinnamon extract inhibits degranulation and de novo synthesis of inflammatory mediators in mast cells.

BACKGROUND: Mast cells (MC) are main effector cells of allergic and other inflammatory reactions; however, only a few anti-MC agents are available for therapy. It has been reported that cinnamon extract (CE) attenuates allergic symptoms by affecting immune cells; however, its influence on MC was not studied so far. Here, we analyzed the effects of CE on human and rodent MC in vitro and in vivo. METHODS: Expression of MC-specific proteases was examined in vivo in duodenum of mice following oral administration of CE. Release of mediators and phosphorylation of signaling molecules were analyzed in vitro in human MC isolated from intestinal tissue (hiMC) or RBL-2H3 cells challenged with CE prior to stimulation by FcεRI cross-linking. RESULTS: Following oral treatment with CE, expression of the mast cell proteases MCP6 and MC-CPA was significantly decreased in mice. In hiMC, CE also caused a reduced expression of tryptase. Moreover, in hiMC stimulated by IgE cross-linking, the release of ß-hexosaminidase was reduced to about 20% by CE. The de novo synthesis of cysteinyl leukotrienes, TNFα, CXCL8, CCL2, CCL3, and CCL4, was almost completely inhibited by CE. The attenuation of mast cell mediators by CE seems to be related to particular signaling pathways, because we found that activation of the MAP kinases ERK, JNK, and p38 as well as of Akt was strongly reduced by CE. CONCLUSION: CE decreases expression of mast cell-specific mediators in vitro and in vivo and thus is a new plant-originated candidate for anti-allergic therapy.

The rhizomes of Alisma orientale and alisol derivatives inhibit allergic response and experimental atopic dermatitis.

The 70% ethanol extract of the rhizome of Alisma orientale (Alismatis rhizome) (AOE) was prepared and found to significantly inhibit 5-lipoxygenase (5-LOX)-catalyzed leukotriene (LT) production from rat basophilic leukemia (RBL)-1 cells and ß-hexosaminidase release by antigen-stimulated RBL-2H3 cells. It also attenuated delayed-type hypersensitivity (DTH) reaction in mice. Among the three major triterpene constituents isolated (i.e., alisol B, alisol B 23-acetate, alisol C 23-acetate) as active principles, alisol B and its 23-acetate strongly and significantly inhibited LT production and ß-hexosaminidase release between 1-10 µM. On the other hand, all these alisol derivatives significantly and strongly inhibited DTH response after oral administration. In addition, AOE (200 mg/kg/d) was for the first time found to considerably alleviate hapten-induced dermatitis symptoms in NC/Nga mice, an animal model of atopic dermatitis. These results indicate that alisol derivatives possess inhibitory activities on immediate-type as well as delayed-type hypersensitivity reactions and may contribute to the anti-allergic action of AOE.

Identification of novel benzimidazole derivatives as inhibitors of leukotriene biosynthesis by virtual screening targeting 5-lipoxygenase-activating protein (FLAP).

Pharmacological suppression of leukotriene biosynthesis by 5-lipoxygenase (5-LO)-activating protein (FLAP) inhibitors is a promising strategy to intervene with inflammatory, allergic and cardiovascular diseases. Virtual screening targeting FLAP based on a combined ligand- and structure-based pharmacophore model led to the identification of 1-(2-chlorobenzyl)-2-(1-(4-isobutylphenyl)ethyl)-1H-benzimidazole (7) as developable candidate. Compound 7 potently suppressed leukotriene formation in intact neutrophils (IC(50)=0.31 µM) but essentially failed to directly inhibit 5-LO suggesting that interaction with FLAP causes inhibition of leukotriene synthesis. For structural optimization, a series of 46 benzimidazole-based derivatives of 7 were synthesized leading to more potent analogues (70-72, 82) with IC(50)=0.12-0.19 µM in intact neutrophils. Together, our results disclose the benzimidazole scaffold bearing an ibuprofen fingerprint as a new chemotype for further development of anti-leukotriene agents.

Anti-inflammatory effects of benfotiamine are mediated through the regulation of the arachidonic acid pathway in macrophages.

Benfotiamine, a lipid-soluble analogue of vitamin B1, is a potent antioxidant that is used as a food supplement for the treatment of diabetic complications. Our recent study (U.C. Yadav et al., Free Radic. Biol. Med. 48:1423-1434, 2010) indicates a novel role for benfotiamine in the prevention of bacterial endotoxin, lipopolysaccharide (LPS)-induced cytotoxicity and inflammatory response in murine macrophages. Nevertheless, it remains unclear how benfotiamine mediates anti-inflammatory effects. In this study, we investigated the anti-inflammatory role of benfotiamine in regulating arachidonic acid (AA) pathway-generated inflammatory lipid mediators in RAW264.7 macrophages. Benfotiamine prevented the LPS-induced activation of cPLA2 and release of AA metabolites such as leukotrienes, prostaglandin E2, thromboxane 2 (TXB2), and prostacyclin (PGI2) in macrophages. Further, LPS-induced expression of AA-metabolizing enzymes such as COX-2, LOX-5, TXB synthase, and PGI2 synthase was significantly blocked by benfotiamine. Furthermore, benfotiamine prevented the LPS-induced phosphorylation of ERK1/2 and expression of transcription factors NF-κB and Egr-1. Benfotiamine also prevented the LPS-induced oxidative stress and protein-HNE adduct formation. Most importantly, compared to specific COX-2 and LOX-5 inhibitors, benfotiamine significantly prevented LPS-induced macrophage death and monocyte adhesion to endothelial cells. Thus, our studies indicate that the dual regulation of the COX and LOX pathways in AA metabolism could be a novel mechanism by which benfotiamine exhibits its potential anti-inflammatory response.

Cysteinyl leukotrienes synthesis is involved in aristolochic acid I-induced apoptosis in renal proximal tubular epithelial cells.

Aristolochic acid I (AAI) is a primary nephrotoxin and carcinogen that is found in some Chinese herbal medicines, and AAI is responsible for the progression of aristolochic acid nephropathy. The membrane associated proteins in the eicosanoid and glutathione metabolism (MAPEG) superfamily are associated with cysteinyl leukotrienes (cysLTs) synthesis. The present study investigated whether cysLTs synthesis was involved in AAI-induced renal proximal tubular epithelial cell injury in LLC-PK1 cells. Based on MAPEG and related molecular events, the potential mechanisms of AAI-induced LLC-PK1 cell injury were explored. AAI triggered the mitochondrial/caspase apoptotic pathway in LLC-PK1 cells, which was indicated by an enhanced Bax/Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome C release, and caspase 3 activation. In addition, AAI-induced cysLTs release was accompanied by selective upregulation of 5-lipoxygenase activating protein (FLAP) and microsomal glutathione S-transferase 3 (mGST3) in a concentration-dependent manner. The FLAP inhibitor MK866 significantly protected cells from AAI-induced apoptosis. Furthermore, activation of extracellular signal-regulated kinase (ERK) 1/2 and inhibition of phosphorylated p38-MAPK were demonstrated at the early phase of AAI treatment. Notably, the MEK/ERK inhibitor U0126 reversed AAI-induced apoptosis and reduced both FLAP, mGST3 and mitochondrial/caspase protein expression. Taken together, these findings suggest that cysLTs synthesis is involved in AAI-induced apoptosis via an ERK activation way.

Potential role of the lipoxygenase derived lipid mediators in atherosclerosis: leukotrienes, lipoxins and resolvins.

Atherogenesis is an inflammatory process with leukocytes infiltrating the arterial intima. The lipoxygenase pathways play a role in leukocyte recruitment through the generation of two classes of arachidonic acid lipid mediators, the leukotrienes and the lipoxins, and one class of omega-3 fatty acid metabolites, the resolvins. There is evidence from animal studies and human genetic studies that the leukotrienes and the enzymes necessary for their generation play a role in atherosclerosis, and possibly even in the development of the vulnerable plaque. Less is known about the effect of the anti-inflammatory lipid mediators in atherosclerosis, the lipoxins and the resolvins. Studies modulating the activity of an enzyme necessary for the production of these lipid mediators, 12/15-lipoxygenase, showed discrepant results in several animal models. Also, human genetic studies have not clearly dissected the effect of the enzyme on atherosclerosis. However, stable forms of the lipoxins and the resolvins protect animals from inflammatory diseases. Whether blocking the leukotrienes or applying anti-inflammatory lipoxins and resolvins will be effective in attenuating human atherosclerosis needs to be demonstrated in future studies. In this review, the biosynthesis of these lipid mediators, their biological effects and the evidence for their possible role in atherosclerosis are discussed with an emphasis on human disease.

FLAP inhibitors for the treatment of inflammatory diseases.

Leukotrienes are lipid inflammatory mediators that are implicated in asthma, COPD, arthritis, cardiovascular disease and cancer. Leukotriene synthesis requires 5-lipoxygenase activating protein (FLAP), which acts as a scaffolding protein for the assembly of other enzymes involved in the leukotriene synthetic pathway occurring at the nuclear envelope of leukocytes. By blocking the formation of both leukotriene B4 and the cysteinyl leukotrienes (ie, LTC4 , LTD4 and LTE4), FLAP inhibitors act as broad-spectrum leukotriene-modifier drugs that may have a wide range of therapeutic applications. FLAP inhibitors such as MK-886, MK-0591 and veliflapon (BAY-X-1005, DG-031) demonstrated promise in clinical trials with patients with inflammatory diseases in the mid 1990 s, but, unlike the 'lukast' class of cysteinyl-leukotriene receptor antagonists, these compounds were not brought to market. The elucidation of the 3D structure of FLAP has enabled novel compound development, and several FLAP inhibitors including 2190914 (AM-103) and GSK-2190915 (both under development by GlaxoSmithKline plc) have entered phase II trials for the treatment of inflammatory disease, including asthma.

Malnutrition promotes prostaglandin over leukotriene production and dysregulates eicosanoid-cytokine crosstalk in activated resident macrophages.

We previously described a murine model of malnutrition that mimicked features of moderate human malnutrition, and led to increased dissemination of Leishmania donovani. In this study, we investigated the effect of malnutrition on macrophage production of cytokines, prostaglandins (PGs), and leukotrienes (LTs). Using either LPS or calcium ionophore A23187 as a stimulus, macrophages from the malnourished mice produced a 3-fold higher PG/LT ((PGE(2)+6-keto-PGF(1alpha))/(LTB(4)+cysteinyl leukotrienes)) ratio than macrophages from well-nourished mice. LPS-stimulated macrophages from the malnourished mice produced decreased levels of TNF-alpha, GM-CSF, and IL-10, but similar levels of IL-6 and NO compared to well-nourished mice. A complex crosstalk between the eicosanoids and cytokines in the LPS-stimulated macrophages from the malnourished mice was evident by the following: (1) high levels of PG secretion despite low levels of TNF-alpha; (2) supplemental IL-10 modulated the excessive PG production; (3) GM-CSF rectified the PG/LT ratio, but did not correct the abnormal cytokine profile; and (4) inhibitors of cyclooxygenase decreased the PG/LT ratio, but did not affect TNF-alpha. Thus, in this model of malnutrition, there is a relative increase in anti-inflammatory PGs compared to pro-inflammatory LTs, which may contribute to immunodeficiency.

Blocking central leukotrienes synthesis affects vasopressin release during sepsis.

Recent studies revealed that vasopressinergic neurons have a high content of cys-leukotriene C(4) (LTC(4)) synthase, a critical enzyme in cys-leukotriene synthesis that may play a role in regulating vasopressin secretion. This study investigates the role of this enzyme in arginine vasopressin (AVP) release during experimentally induced sepsis. Male Wistar rats received an i.c.v. injection of 3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2, 2-dimethylpropanoic acid (MK-886) (1.0 microg/kg), a leukotrienes (LTs) synthesis inhibitor, or vehicle, 1 h before cecal ligation and puncture (CLP) or sham operation. In one group of animals the survival rate was monitored for 3 days. In another group, the animals were decapitated at 0, 4, 6, 18 and 24 h after CLP or sham operation, and blood was collected for hematocrit, serum sodium and nitrate, plasma osmolality, protein and AVP determination. A third group was used for blood pressure measurements. The neurohypophysis was removed for quantification of AVP content, and the hypothalamus was dissected for LTC(4) synthase analysis by Western blot. Mortality after CLP was reduced by the central administration of MK-886. The increase in plasma AVP levels and hypothalamus LTC(4) synthase content in the initial phase of sepsis was blocked, whereas the decrease in neurohypophyseal AVP content was partially reversed. Also the blood pressure drop was abolished in this phase. The increase of serum nitric oxide and hematocrit was reduced, and the decrease in plasma protein and osmolality was not affected by the LTs blocker. In the final phase of sepsis, the plasma AVP level and the hypothalamic LTC(4) synthase content were at basal levels. The central administration of MK-886 increased the hypothalamic LTC(4) synthase content but did not alter the plasma and neurohypophysis AVP levels observed, or the blood pressure during this phase. These results suggest that the central LTs are involved in the vasopressin release observed during sepsis.

5-lipoxygenase-inhibitory constituents from Schizandra fructus and Magnolia flos.

In order to establish the antiallergic properties of Schisandra fructus and Magnolia flos, several compounds isolated from these plants were tested for 5-lipoxygenase (5-LOX) inhibitory activity in vitro, for the first time. The compounds including schizandrins, schisandrols, gomisins, fargesin, eudesmin and lirioresinol B dimethyl ether, inhibited 5-LOX-catalysed leukotriene production from A23187-treated rat basophilic leukemia (RBL-1) cells at concentrations of 1-100 microm. In particular, constituents such as schisandrol A and gomisins showed potent inhibitory activity (IC(50)s < 10 microm) on 5-LOX-catalysed leukotriene production, but were much less active on cyclooxygenase-2-catalysed prostaglandin E(2) and inducible nitric oxide-catalysed NO production. These compounds have the potential to be developed as novel antiallergic agents and may contribute to the antiallergic pharmacological use of these plant materials in Chinese medicine.

Combination therapies that inhibit cyclooxygenase-2 and leukotriene synthesis prevent disease in murine collagen induced arthritis.

OBJECTIVE AND DESIGN: To determine the effect of combinations of cyclooxygenase (COX) inhibitors and inhibitors of leukotriene (LT) syntheses on collagen induced arthritis (CIA) in mice. METHODS: The CIA model was evaluated for the presence of eicosanoids in the paw tissue. Several selective cyclooxygenase 2 (COX-2) inhibitors or non-selective non-steroidal anti inflammatory drugs (NSAIDs) were evaluated alone or in combination with leukotriene (LT) synthesis inhibitors in the CIA model. RESULTS: Arthritic paw tissue showed increased levels of prostaglandins and leukotrienes in comparison to normal paws. Analysis of mRNA levels indicated the inducible form of the COX-2 enzyme to be the source of prostaglandins. NSAIDs, COX-2 or leukotriene synthesis inhibitors administered alone in CIA decreased severity but had little effect on disease incidence. However, the combination of selective COX-2 inhibitors with leukotriene synthesis inhibitors produced significant decreases in both incidence and severity, suggesting an additive or synergistic effect. This effect was reversible with removal of drug. Little decrease in incidence was observed with the NSAID/5-LO inhibitor combinations. CONCLUSIONS: These results suggest that the induction of the disease in CIA is mediated by products of the COX-2 enzyme and LTB4 production, and that blockade of both pathways is required to prevent CIA.