Immunomodulatory effects of aqueous birch pollen extracts and phytoprostanes on primary immune responses in vivo

Phytoprostanes and phytofurans: Bioactive compounds in aerial parts of Acacia cyanophylla Lindl

The relevance of oxylipins as biomarkers of oxidative stress has been established in recent years. Phytoprostanes and phytofurans are plant metabolites derived from peroxidation of α-linolenic acid (ALA) induced by ROS. Previous findings have suggested new valuable biological properties for these new active compounds in the frame of diverse pathophysiological situations and health constraints. Lipidomic profiling of different aerial parts of the same Acacia cyanophylla Lindl. specimen, was evaluated for the first time here, using LC-MS/MS technology. Analysis revealed the existence of six PhytoPs and three PhytoFs. Stems have the highest amount of these metabolites with 179.35 ng/g and 320.79 ng/g respectively. This first complete profile paves the way to explore Acacia cyanophylla Lindl. as a source of plant oxylipins for therapeutic or pharmaceutical uses.

Egg yolk lipids induce sensitization to egg white proteins in a mouse model without adjuvant and exacerbate Th2 responses to egg white in cells from allergic patients

This study evaluates the influence of egg lipid fractions in the induction of allergic sensitization to egg white (EW) proteins, using a mouse model of orally adjuvant-free induced allergy. Egg triglycerides (TG) and phospholipids (PL), and to a higher extent the whole egg lipid fraction (EL), induced allergy to EW proteins characterized by increased EW-specific IgG1. EL also increased EW-specific IgE. The administration to mice of a mixture of EW and EL increased the intestinal expression of Il33, Il25, and Tslp, the secretion of IL-33 and IL-6, the expansion of group 2 innate lymphoid cells, the regulation of Gata3, Il4 and Il13, dendritic cell (DC) activation and expression of DC molecules that drive Th2 differentiation. TG promoted the absorption of proteins through the intestinal epithelium, enhancing local Th2 responses, while PL favoured the delivery of antigens to the Peyer's Patches. This differential modulation of the site of absorption of egg proteins determined the different behaviour of TG and PL. Egg yolk lipids also induced activation of Th2-inducing innate responses on intestinal human cells in vitro and enhanced adaptive Th2 functions through the activation of DCs in egg-allergic subjects.

Therapeutic Potential of Plant Oxylipins

For immobile plants, the main means of protection against adverse environmental factors is the biosynthesis of various secondary (specialized) metabolites. The extreme diversity and high biological activity of these metabolites determine the researchers' interest in plants as a source of therapeutic agents. Oxylipins, oxygenated derivatives of fatty acids, are particularly promising in this regard. Plant oxylipins, which are characterized by a diversity of chemical structures, can exert protective and therapeutic properties in animal cells. While the therapeutic potential of some classes of plant oxylipins, such as jasmonates and acetylenic oxylipins, has been analyzed thoroughly, other oxylipins are barely studied in this regard. Here, we present a comprehensive overview of the therapeutic potential of all major classes of plant oxylipins, including derivatives of acetylenic fatty acids, jasmonates, six- and nine-carbon aldehydes, oxy-, epoxy-, and hydroxy-derivatives of fatty acids, as well as spontaneously formed phytoprostanes and phytofurans. The presented analysis will provide an impetus for further research investigating the beneficial properties of these secondary metabolites and bringing them closer to practical applications.

How Do Pollen Allergens Sensitize?

Plant pollen is one of the main sources of allergens causing allergic diseases such as allergic rhinitis and asthma. Several allergens in plant pollen are panallergens which are also present in other allergen sources. As a result, sensitized individuals may also experience food allergies. The mechanism of sensitization and development of allergic inflammation is a consequence of the interaction of allergens with a large number of molecular factors that often are acting in a complex with other compounds, for example low-molecular-mass ligands, which contribute to the induction a type 2-driven response of immune system. In this review, special attention is paid not only to properties of allergens but also to an important role of their interaction with lipids and other hydrophobic molecules in pollen sensitization. The reactions of epithelial cells lining the nasal and bronchial mucosa and of other immunocompetent cells will also be considered, in particular the mechanisms of the activation of B and T lymphocytes and the formation of allergen-specific antibody responses.

The Role of Lipids in Allergic Sensitization: A Systematic Review

Background: Immunoglobulin E (IgE)-mediated allergies are increasing in prevalence, with IgE-mediated food allergies currently affecting up to 10% of children and 6% of adults worldwide. The mechanisms underpinning the first phase of IgE-mediated allergy, allergic sensitization, are still not clear. Recently, the potential involvement of lipids in allergic sensitization has been proposed, with reports that they can bind allergenic proteins and act on immune cells to skew to a T helper type 2 (Th2) response. Objectives: The objective of this systematic review is to determine if there is strong evidence for the role of lipids in allergic sensitization. Methods: Nineteen studies were reviewed, ten of which were relevant to lipids in allergic sensitization to food allergens, nine relevant to lipids in aeroallergen sensitization. Results: The results provide strong evidence for the role of lipids in allergies. Intrinsic lipids from allergen sources can interact with allergenic proteins to predominantly enhance but also inhibit allergic sensitization through various mechanisms. Proposed mechanisms included reducing the gastrointestinal degradation of allergenic proteins by altering protein structure, reducing dendritic cell (DC) uptake of allergenic proteins to reduce immune tolerance, regulating Th2 cytokines, activating invariant natural killer T (iNKT) cells through CD1d presentation, and directly acting upon toll-like receptors (TLRs), epithelial cells, keratinocytes, and DCs. Conclusion: The current literature suggests intrinsic lipids are key influencers of allergic sensitization. Further research utilising human relevant in vitro models and clinical studies are needed to give a reliable account of the role of lipids in allergic sensitization.

Analysis of Flavonoid Metabolites in Watercress (Nasturtium officinale R. Br.) and the Non-Heading Chinese Cabbage (Brassica rapa ssp. chinensis cv. Aijiaohuang) Using UHPLC-ESI-MS/MS

Flavonoids from plants play an important role in our diet. Watercress is a special plant that is rich in flavonoids. In this study, four important watercress varieties were compared with non-heading Chinese cabbage by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS). A total of 132 flavonoid metabolites (including 8 anthocyanins, 2 dihydroflavone, 3 dihydroflavonol, 1 flavanols, 22 flavones, 11 flavonoid carbonosides, 82 flavonols, and 3 isoflavones) were detected. Flavonoid metabolites varied widely in different samples. Both the non-heading Chinese cabbage and the variety of watercress from Guangdong, China, had their own unique metabolites. This work is helpful to better understand flavonoid metabolites between the non-heading Chinese cabbage and the other four watercress varieties, and to provide a reliable reference value for further research.

First Total Synthesis of Phytoprostanes with Prostaglandin-Like Configuration, Evidence for Their Formation in Edible Vegetable Oils and Orienting Study of Their Biological Activity

Phytoprostanes (PhytoP) are natural products, which form in plants under oxidative stress conditions from α-linolenic acid. However, their epimers with relative prostaglandin configuration termed phytoglandins (PhytoG) have never been detected in Nature, likely because of the lack of synthetic reference material. Here, the first asymmetric total synthesis of such compounds, namely of PhytoGF_1α (9-epi-16-F_1t -PhytoP) and its diastereomer ent-16-epi-PhytoGF_1α (ent-9,16-diepi-16-F_1t -PhytoP), has been accomplished. The synthetic strategy is based on radical anion oxidative cyclization, copper(I)-mediated alkyl-alkyl coupling and enantioselective reduction reactions. A UHPLC-MS/MS study using the synthesized compounds as standards indicates PhytoG formation at significant levels during autoxidation of α-linolenic acid in edible vegetable oils. Initial testing of synthetic PhytoGs together with F₁ -PhytoP and 15-F_2t -IsoP derivatives for potential interactions with the PGF_2α (FP) receptor did not reveal significant activity. The notion that PUFA-derived oxidatively formed cyclic metabolites with prostaglandin configuration do not form to a significant extent in biological or food matrices has to be corrected. Strong evidence is provided that oxidatively formed PhytoG metabolites may be ingested with plant-derived food, which necessitates further investigation of their biological profile.

Bioavailable phytoprostanes and phytofurans from Gracilaria longissima have anti-inflammatory effects in endothelial cells

BACKGROUND

An array of bioactive compounds with health-promoting effects has been described in several species of macroalgae. Among them, phytoprostanes (PhytoPs) and phytofurans (PhytoFs), both autoxidation products of α-linolenic acid, have been seen to exert immunomodulatory and antiinflammatory activities in vitro. The purpose of this study was to explore the bioaccesibility, bioavailability, and bioactivity of PhytoPs and PhytoFs obtained from the edible red algae Gracilaria longissima, and to gain insight into the anti-inflammatory activity of their bioavailable fraction in human endothelial cells.

METHODS

The PhytoPs and PhytoFs profile and concentration of G. longissima were determined by UHPLC-QqQ-MS/MS. Algal samples were processed following a standardised digestion method including gastric, intestinal, and gastrointestinal digestion. The bioavailability of the PhytoPs and PhytoFs in the characterized fractions was assessed in a Caco-2 cell monolayer model of the intestinal barrier. The inflammation response of these prostaglandin-like compounds in human endothelial cells, after intestinal absorption, was investigated in vitro.

RESULTS

Simulated digestions significantly reduced the concentration of PhytoPs and PhytoFs up to 1.17 and 0.42 μg per 100 g, respectively, on average, although permeability through the Caco-2 cell monolayer was high (up to 88.2 and 97.7%, on average, respectively). PhytoP and PhytoF-enriched extracts of raw algae impaired the expression of ICAM-1 and IL-6 inflammation markers. The inflammation markers progressed in contrast to the relative concentrations of bioactive oxylipins, suggesting pro- or anti-inflammatory activity on their part. In this aspect, the cross-reactivity of these compounds with diverse receptors, and their relative concentration could explain the diversity of the effects found in the current study.

CONCLUSIONS

The results indicate that PhytoPs and PhytoFs display complex pharmacological profiles probably mediated through their different actions and affinities in the endothelium.

Phytoprostanes and phytofurans modulate COX-2-linked inflammation markers in LPS-stimulated THP-1 monocytes by lipidomics workflow

Inflammation is a fundamental pathophysiological process which occurs in the course of several diseases. The present work describes the capacity of phytoprostanes (PhytoPs) and phytofurans (PhytoFs) (plant oxylipins), present in plant-based foods, to modulate inflammatory processes mediated by prostaglandins (PGs, human oxylipins) in lipopolysaccharide (LPS)-stimulated THP-1 monocytic cells, through a panel of 21 PGs and PG's metabolites, analyzed by UHPLC-QqQ-ESI-MS/MS. Also, the assessment of the cytotoxicity of PhytoPs and PhytoFs on THP-1 cells evidenced percentages of cell viability higher than 90% when treated with up to 100 μM. Accordingly, 50 μM of the individual PhytoPs and PhytoFs 9-F_1t-PhytoP, 9-epi-9-F_1t-PhytoP, ent-16-F_1t-PhytoP, ent-16-epi-16-F_1t-PhytoP, ent-9-D_1t-PhytoP, 16-B₁-PhytoP, 9-L₁-PhytoP, ent-16(RS)-9-epi-ST-Δ¹⁴-10-PhytoF, ent-9(RS)-12-epi-ST-Δ¹⁰-13-PhytoF, and ent-16(RS)-13-epi-ST-Δ¹⁴-9-PhytoF were evaluated on their capacity to modulate the expression of inflammatory markers. The results obtained demonstrated the presence of 7 metabolites (15-keto-PGF_2α, PGF_2α, 11β-PGF_2α, PGE₂, PGD₂, PGDM, and PGF_1α) in THP-1 monocytic cells, which expression was significantly modulated when exposed to LPS. The evaluation of the capacity of the individual PhytoPs and PhytoFs to revert the modification of the quantitative profile of PGs induced by LPS revealed the anti-inflammatory ability of 9-F_1t-PhytoP, ent-9-D_1t-PhytoP, 16-B₁-PhytoP, 9-L₁-PhytoP, and ent-9(RS)-12-epi-ST-Δ¹⁰-13-PhytoF, as evidenced by their capacity to prevent the up-regulation of 15-keto-PGF_2α, PGF_2α, PGE₂, PGF_1α, PGDM, and PGD₂ induced by LPS. These results indicated that specific plant oxylipins can protect against inflammatory events, encouraging further investigations using plant-based foods rich in these oxylipins or enriched extracts, to identify specific bioactivities of the diverse individual molecules, which can be useful for nutrition and health in the frame of well-defined pathophysiological processes.

Oxidized Products of α-Linolenic Acid Negatively Regulate Cellular Survival and Motility of Breast Cancer Cells

Despite recent advances in our understanding of the biological processes leading to the development and progression of cancer, there is still a need for new and effective agents to treat this disease. Phytoprostanes (PhytoPs) and phytofurans (PhytoFs) are non-enzymatically oxidized products of α-linolenic acid that are present in seeds and vegetable oils. They have been shown to possess anti-inflammatory and apoptosis-promoting activities in macrophages and leukemia cells, respectively. In this work, seven PhytoPs (PP1–PP7) and one PhytoFs (PF1) were evaluated for their cytotoxic, chemosensitization, and anti-migratory activities using the MCF-7 and MDA-MB-231 breast cancer cell lines. Among the tested compounds, only three PhytoPs had a significant effect on cell viability compared to the control group: Ent-9-L₁-PhytoP (PP6) decreased cell viability in both cell lines, while 16-F_1t-PhytoP (PP1) and 9-L₁-PhytoP (PP5) decreased viability of MCF-7 and MDA-MB-231 cells, respectively. When combined with a sub-cytotoxic dose of doxorubicin, these three PhytoPs displayed significantly enhanced cytotoxic effects on MCF-7 cells while the chemotherapeutic drug alone had no effect. In cellular motility assays, Ent-9-(RS)-12-epi-ST-Δ¹⁰-13-PhytoF could significantly inhibit cellular migration of MDA-MB-231 cells. In addition, Ent-9-(RS)-12-epi-ST-Δ¹⁰-13-PhytoF also enhanced cellular adhesion of MDA-MB-231 cells.

Multiple roles of Bet v 1 ligands in allergen stabilization and modulation of endosomal protease activity

Background

Over 100 million people worldwide suffer from birch pollen allergy. Bet v 1 has been identified as the major birch pollen allergen. However, the molecular mechanisms of birch allergic sensitization, including the roles of Bet v 1 and other components of the birch pollen extract, remain incompletely understood. Here, we examined how known birch pollen–derived molecules influence the endolysosomal processing of Bet v 1, thereby shaping its allergenicity.

Methods

We analyzed the biochemical and immunological interaction of ligands with Bet v 1. We then investigated the proteolytic processing of Bet v 1 by endosomal extracts in the presence and absence of ligands, followed by a detailed kinetic analysis of Bet v 1 processing by individual endolysosomal proteases as well as the T‐cell epitope presentation in BMDCs.

Results

We identified E₁ phytoprostanes as novel Bet v 1 ligands. Pollen‐derived ligands enhanced the proteolytic resistance of Bet v 1, affecting degradation kinetics and preferential cleavage sites of the endolysosomal proteases cathepsin S and legumain. E₁ phytoprostanes exhibited a dual role by stabilizing Bet v 1 and inhibiting cathepsin protease activity.

Conclusion

Bet v 1 can serve as a transporter of pollen‐derived, bioactive compounds. When carried to the endolysosome, such compounds can modulate the proteolytic activity, including its processing by cysteine cathepsins. We unveil a paradigm shift from an allergen‐centered view to a more systemic view that includes the host endolysosomal enzymes.

Lipid Mediators From Timothy Grass Pollen Contribute to the Effector Phase of Allergy and Prime Dendritic Cells for Glycolipid Presentation

Plant pollen are an important source of antigens that evoke allergic responses. Protein antigens have been the focus of studies aiming to elucidate the mechanisms responsible for allergic reactions to pollen. However, proteins are not the sole active agent present in pollen. It is known that pollen grains contain lipids essential for its reproduction and bioactive lipid mediators. These small molecular compounds are co-delivered with the allergens and hence have the potential to modulate the immune response of subjects by activating their innate immune cells. Previous reports showed that pollen associated lipid mediators exhibited neutrophil- and eosinophil-chemotactic activity and induced polarization of dendritic cells (DCs) toward a Th2-inducing phenotype. In our study we performed chemical analyses of the pollen associated lipids, that are rapidly released upon hydration. As main components we have identified different types of phytoprostanes (PhytoPs), and for the first time phytofurans (PhytoFs), with predominating 16-F_1t-PhytoPs (PPF₁-I), 9-F_1t-PhytoPs (PPF₁-II), 16-E_1t-PhytoPs (PPE₁-I) and 9-D_1t-PhytoPs (PPE₁-II), and 16(RS)-9-epi-ST-Δ¹⁴-10-PhytoFs. Interestingly 16-E_1t-PhytoP and 9-D_1t-PhytoPs were found to be bound to glycerol. Lipid-containing samples (aqueous pollen extract, APE) induced murine mast cell chemotaxis and IL-6 release, and enhanced their IgE-dependent degranulation, demonstrating a role for these lipids in the immediate effector phase of allergic inflammation. Noteworthy, mast cell degranulation seems to be dependent on glycerol-bound, but not free phytoprostanes. On murine dendritic cells, APE selectively induced the upregulation of CD1d, likely preparing lipid-antigen presentation to iNKT cells. Our report contributes to the understanding of the activity of lipid mediators in the immediate effector phase of allergic reactions but identifies a yet undescribed pathway for the recognition of pollen-derived glycolipids by iNKT cells.

Role of dietary lipids in food allergy

The prevalence of food allergy is raising in industrialized countries, but the mechanisms behind this increased incidence are not fully understood. Environmental factors are believed to play a role in allergic diseases, including lifestyle influences, such as diet. There is a close relationship between allergens and lipids, with many allergenic proteins having the ability to bind lipids. Dietary lipids exert pro-inflammatory or anti-inflammatory functions on cells of the innate immunity and influence antigen presentation to cells of the adaptive immunity. In addition to modifying the immunostimulating properties of proteins, lipids also alter their digestibility and intestinal absorption, changing allergen bioavailability. This study provides an overview of the role of dietary lipids in food allergy, taking into account epidemiological information, as well as results of mechanistic investigations using in vivo, ex vivo and in vitro models. The emerging link among high-fat diets, obesity, and allergy is also discussed.

Structural/Functional Matches and Divergences of Phytoprostanes and Phytofurans with Bioactive Human Oxylipins

Structure-activity relationship (SAR) constitutes a crucial topic to discover new bioactive molecules. This approach initiates with the comparison of a target candidate with a molecule or a collection of molecules and their attributed biological functions to shed some light in the details of one or more SARs and subsequently using that information to outline valuable application of the newly identified compounds. Thus, while the empiric knowledge of medicinal chemistry is critical to these tasks, the results retrieved upon dedicated experimental demonstration retrieved resorting to modern high throughput analytical approaches and techniques allow to overwhelm the constraints adduced so far to the successful accomplishment of such tasks. Therefore, the present work reviews critically the evidences reported to date on the occurrence of phytoprostanes and phytofurans in plant foods, and the information available on their bioavailability and biological activity, shedding some light on the expectation waken up due to their structural similarities with prostanoids and isoprostanes.

Secondary Metabolites in Allergic Plant Pollen Samples Modulate Afferent Neurons and Murine Tracheal Rings

Plant pollens are strong airborne elicitors of asthma. Their proteinaceous allergens have been studied intensively, but little is known about a possible contribution of pollen secondary metabolites to the nonallergic exacerbation of asthma. Pollen samples originating from 30 plant species were analyzed by HPLC coupled to PDA, ESIMS, and ELSD detectors and off-line NMR spectroscopy. Polyamine conjugates, flavonoids, and sesquiterpene lactones were identified. Polyamine conjugates were characteristic of all Asteraceae species. The presence of sesquiterpene lactones in Asteraceae pollen varied between species and pollen lots. All plant pollen, including those from non-Asteraceae species, contained to some extent electrophiles as determined by their reaction with N-acetyl-l-cysteine. Selected pollen extracts and pure compounds were tested in murine afferent neurons and in murine tracheal preparations. Tetrahydrofuran extracts of Ambrosia artemisiifolia and Ambrosia psilostachya pollen and a mixture of sesquiterpene lactones coronopilin/parthenin increased the intracellular Ca²⁺ concentration in 15%, 32%, and 37% of cinnamaldehyde-responsive neurons, respectively. In organ bath experiments, only the sesquiterpene lactones tested induced a weak dilatation of naïve tracheas and strongly lowered the maximal methacholine-induced tracheal constriction. A tetrahydrofuran extract of A. psilostachya and coronopilin/parthenin led to a time-dependent relaxation of the methacholine-preconstricted trachea. These results provide the first evidence for a potential role of pollen secondary metabolites in the modulation of the tracheal tone.

Total syntheses of all tri-oxygenated 16-phytoprostane classes via a common precursor constructed by oxidative cyclization and alkyl-alkyl coupling reactions as the key steps

A unified strategy for the total synthesis of the methyl esters of all phytoprostane (PhytoP) classes bearing two ring-oxygen atoms based on an orthogonally protected common precursor is described. Racemic 16-F_1t-, 16-E₁-PhytoP and their C-16 epimers, which also occur as racemates in Nature, were successfully obtained. The first total synthesis of very sensitive 16-D_1t-PhytoP succeeded, however, it quickly isomerized to more stable, but so far also unknown Δ¹³-16-D_1t-PhytoP, which may serve as a more reliable biomarker for D-type PhytoP. The dioxygenated cyclopentane ring carrying the ω-chain with the oxygen functionality in the 16-position was approached by a radical oxidative cyclization mediated by ferrocenium hexafluorophosphate and TEMPO. The α-chain was introduced by a new copper-catalyzed alkyl-alkyl coupling of a 6-heptenyl Grignard reagent with a functionalized cyclopentylmethyl triflate.

The Role of Lipids in Development of Allergic Responses

Most allergic diseases are caused by activation of Th2 type immune responses resulting in the production of specific IgE against proteins found in normally harmless substances such as pollen, mites, epithelia or food. Allergenic substances are composed, in addition to proteins, of other compounds such as carbohydrates and lipids. Those lipids are able to promote the development of Th2-type responses associated with allergy. There are lipids found in pollen, milk or insect venom that are specifically recognized by CD1 restricted unconventional T lymphocytes, which can promote allergic reactions. Furthermore, a large number of allergens are proteins containing hydrophobic parts that specifically bind lipids that are capable to favor allergenic immune responses. Also, lipids associated to substances like pollen, dander, epithelia or the bacteria can act on cells of the innate system, including dendritic cells, which in turn lead to the differentiation of Th2-type clones. Finally, lipids may also influence the ability of allergens to be exposed to the immune system within the oral, respiratory or intestinal mucosa where allergic response occurs with great frequency.

Inhibition of α-glucosidase and α-amylase by Spanish extra virgin olive oils: The involvement of bioactive compounds other than oleuropein and hydroxytyrosol

Despite the wide use of extra virgin olive oil (EVOO) to combat several diseases, the antidiabetic and anti-cholinesterase activity of Spanish EVOO have not been assessed. In order to evaluate which compounds are responsible for these activities of five Spanish EVOOs, in addition to flavonoids, we investigated for the first time the effect of the contents of carotenoids, fatty acids (FAs), and phytoprostanes (PhytoPs) on four enzymes: α-glucosidase, α-amylase, acetylcholinesterase, and butyrylcholinesterase. The extracts of these five Spanish EVOOs were found to contain three flavones, three carotenoids, six FAs, and seven classes of PhytoPs. The samples exhibited no in vitro anti-cholinesterase activity but presented strong antidiabetic activity, in the order: 'Arbequina'≈'Picual'≈'Cuquillo'>'Hojiblanca'>'Cornicabra'. The samples showed a higher in vitro hypoglycemic effect than individual or mixed standards, possibly due to interaction between multiple identified compounds and/or a very complex multivariate interaction between other factors.

Allergen-Associated Immunomodulators: Modifying Allergy Outcome

The prevalence of allergies is increasing since mid twentieth century; however the underlying causes of this increase are not fully clear. Understanding the mechanism by which a harmless protein becomes an allergen provides us with the basis to prevent and treat these diseases. Although most studies on allergen immunogenicity have traditionally focused on structural properties of the proteins, it is increasingly clear that allergenicity cannot be determined only based on structural features of the allergenic proteins. In fact, allergens do not encounter human facings as isolated molecules but contained in complex mixtures of proteins, carbohydrates and lipids, such as pollen grains or foods. As a result, attention has lately been directed to examine whether allergen-associated molecules exhibit immune-regulatory properties. The present review aims to illustrate some examples of how non-protein molecules accompanying the allergen can modulate allergic responses.

Effect of the season on the free phytoprostane content in Cornicabra extra virgin olive oil from deficit-irrigated olive trees

BACKGROUND

The effect of regulated deficit irrigation (RDI) on the phytoprostane (PhytoP) content in extra virgin olive (Olea europaea L., cv. Cornicabra) oil (EVOO) was studied. During the 2012 and 2013 seasons, T0 plants were irrigated at 100% ETc, while T1 and T2 plants were irrigated avoiding water deficit during phases I and III of fruit growth and saving water during the non-critical phenological period of pit hardening (phase II), developing a more severe water deficit in T2 plants. In 2013, a fourth treatment (T3) was also performed, which was similar to T2 except that water saving was from the beginning of phase II to 15 days after the end of phase II.

RESULTS

9-F1t -PhytoP, 9-epi-9-F1t -PhytoP, 9-epi-9-D1t -PhytoP, 9-D1t -PhytoP, 16-B1 -PhytoP and 9-L1 -PhytoP were present in Cornicabra EVOO, and their contents increased in the EVOO from RDI plants.

CONCLUSION

Deficit irrigation during pit hardening or for a further period of 2 weeks thereafter to increase irrigation water saving is clearly critical for EVOO composition because of the enhancement of free PhytoPs, which have potential beneficial effects on human health. The response of individual free PhytoPs to changes in plant water status was not as perceptible as expected, preventing their use as biomarkers of water stress.

Biologically Active Oxylipins from Enzymatic and Nonenzymatic Routes in Macroalgae

Marine algae are rich and heterogeneous sources of great chemical diversity, among which oxylipins are a well-recognized class of natural products. Algal oxylipins comprise an assortment of oxygenated, halogenated, and unsaturated functional groups and also several carbocycles, varying in ring size and position in lipid chain. Besides the discovery of structurally diverse oxylipins in macroalgae, research has recently deciphered the role of some of these metabolites in the defense and innate immunity of photosynthetic marine organisms. This review is an attempt to comprehensively cover the available literature on the chemistry, biosynthesis, ecology, and potential bioactivity of oxylipins from marine macroalgae. For a better understanding, enzymatic and nonenzymatic routes were separated; however, both processes often occur concomitantly and may influence each other, even producing structurally related molecules.

Pollen-derived nonallergenic substances enhance Th2-induced IgE production in B cells

BACKGROUND

B cells play a central role in IgE-mediated allergies. In damaged airway epithelium, they are exposed directly to aeroallergens. We aimed to assess whether direct exposure of B cells to pollen constituents affects allergic sensitization.

METHODS

B cells from murine splenocytes and from blood samples of healthy donors were incubated for 8 days under Th2-like conditions with aqueous ragweed pollen extracts (Amb-APE) or its constituents. Secreted total IgM, IgG, and IgE was quantified by ELISA. Additionally, birch, grass, or pine-pollen extracts were tested. The number of viable cells was evaluated by ATP measurements. B-cell proliferation was measured by CFSE staining. IgE class switch was analyzed by quantitation of class switch transcripts. In an OVA/Alum i.p.-sensitization mouse model, Amb-APE was intranasally instilled for 11 consecutive days.

RESULTS

Upon Th2 priming of murine B cells, ragweed pollen extract caused a dose-dependent increase in IgE production, while IgG and IgM were not affected. The low-molecular-weight fraction and phytoprostane E1 (PPE1) increased IgE production, while Amb a 1 did not. PPE1 enhanced IgE also in human memory B cells. Under Th1 conditions, Amb-APE did not influence immunoglobulin secretion. The IgE elevation was not ragweed specific. It correlated with proliferation of viable B cells, but not with IgE class switch. In vivo, Amb-APE increased total IgE and showed adjuvant activity in allergic airway inflammation.

CONCLUSIONS

Aqueous pollen extracts, the protein-free fraction of Amb-APE, and the pollen-contained substance PPE1 specifically enhance IgE production in Th2-primed B cells. Thus, pollen-derived nonallergenic substances might be responsible for B-cell-dependent aggravation of IgE-mediated allergies.

Dependency of Phytoprostane Fingerprints of Must and Wine on Viticulture and Enological Processes

Wine is one of the most consumed alcoholic beverages around the world. Red wine has demonstrated several benefits for health maintenance. One group of potential anti-inflammatory compounds is the phytoprostanes, oxidative degradation products of linolenic acid. The aim of the present study was to measure, for the first time, the phytoprostane content in wine and must by an UHPLC-QqQ-MS/MS method after solid-phase extraction. The data showed two predominant classes of phytoprostanes: F1- and D1-phytoprostane series. In wines, the total phytoprostane concentration ranged from 134.1 ± 2.3 to 216.2 ± 3.06 ng/mL. Musts showed concentrations between 21.4 ± 0.8 and 447.1 ± 15.8 ng/mL. The vinification and aging procedures for the production of wine seem to influence the final phytoprostane levels in red wine and to modify the phytoprostane profile. The high concentrations observed and previous reports on anti-inflammatory effects of phytoprostanes make further research on the benefits of phytoprostanes more important.

Pollen-derived adenosine is a necessary cofactor for ragweed allergy

BACKGROUND

Ragweed (Ambrosia artemisiifolia) is a strong elicitor of allergic airway inflammation with worldwide increasing prevalence. Various components of ragweed pollen are thought to play a role in the development of allergic responses. The aim of this study was to identify critical factors for allergenicity of ragweed pollen in a physiological model of allergic airway inflammation.

METHODS

Aqueous ragweed pollen extract, the low molecular weight fraction or the major allergen Amb a 1 was instilled intranasally on 1-11 consecutive days, and allergic airway inflammation was evaluated by bronchoalveolar lavage, lung histology, serology, gene expression in lung tissue, and measurement of lung function. Pollen-derived adenosine was removed from the extract enzymatically to analyze its role in ragweed-induced allergy. Migration of human neutrophils and eosinophils toward supernatants of ragweed-stimulated bronchial epithelial cells was analyzed.

RESULTS

Instillation of ragweed pollen extract, but not of the major allergen or the low molecular weight fraction, induced specific IgG1 , pulmonary infiltration with inflammatory cells, a Th2-associated cytokine signature in pulmonary tissue, and impaired lung function. Adenosine aggravated ragweed-induced allergic lung inflammation. In vitro, human neutrophils and eosinophils migrated toward supernatants of bronchial epithelial cells stimulated with ragweed extract only if adenosine was present.

CONCLUSIONS

Pollen-derived adenosine is a critical factor in ragweed-pollen-induced allergic airway inflammation. Future studies aim at therapeutic strategies to control these allergen-independent pathways.

Nonenzymatic α-Linolenic Acid Derivatives from the Sea: Macroalgae as Novel Sources of Phytoprostanes

Phytoprostanes, autoxidation products of α-linolenic acid, have been studied in several plant species, but information regarding the natural occurrence of this large family of biologically active oxidized lipids in macroalgae is still scarce. In this work, the free phytoprostane composition of 24 macroalgae species belonging to Chlorophyta, Phaeophyta, and Rhodophyta was determined through a recently validated UHPLC-QqQ-MS/MS method. The phytoprostane profiles varied greatly among all samples, F1t-phytoprostanes and L1-phytoprostanes being the predominant and minor classes, respectively. No correlation between the amounts of α-linolenic acid in alga material and phytoprostane content was found. Therefore, it was hypothesized that the observed variability could be species-specific or result from interspecific interactions. This study provides new insight about the occurrence of phytoprostanes in macroalgae and opens doors for future exploitation of these marine photosynthetic organisms as sources of potentially bioactive oxylipins, encouraging their incorporation in food products and nutraceutical and pharmaceutical preparations for human health.

Water deficit during pit hardening enhances phytoprostanes content, a plant biomarker of oxidative stress, in extra virgin olive oil

No previous information exists on the effects of water deficit on the phytoprostanes (PhytoPs) content in extra virgin olive oil from fruits of mature olive (Olea europaea L. cv. Cornicabra) trees during pit hardening. PhytoPs profile in extra virgin olive oil was characterized by the presence of 9-F1t-PhytoP, 9-epi-9-F1t-PhytoP, 9-epi-9-D1t-PhytoP, 9-D1t-PhytoP, 16-B1-PhytoP + ent-16-B1-PhytoP, and 9-L1-PhytoP + ent-9-L1-PhytoP. The qualitative and quantitative differences in PhytoPs content with respect to those reported by other authors indicate a decisive effect of cultivar, oil extraction technology, and/or storage conditions prone to autoxidation. The pit hardening period was critical for extra virgin olive oil composition because water deficit enhanced the PhytoPs content, with the concomitant potential beneficial aspects on human health. From a physiological and agronomical point of view, 9-F1t-PhytoP, 9-epi-9-F1t-PhytoP, and 16-B1-PhytoP + ent-16-B1-PhytoP could be considered as early candidate biomarkers of water stress in olive tree.

Innate responses to pollen allergens

PURPOSE OF REVIEW

The aim of the present review was to discuss the effects of pollen components on innate immune responses.

RECENT FINDINGS

Pollens contain numerous factors that can stimulate an innate immune response. These include intrinsic factors in pollens such as nicotinamide adenine dinucleotide phosphate oxidases, proteases, aqueous pollen proteins, lipids, and antigens. Each component stimulates innate immune response in a different manner. Pollen nicotinamide adenine dinucleotide phosphate oxidases induce reactive oxygen species generation and recruit neutrophils that stimulate subsequent allergic inflammation. Pollen proteases damage epithelial barrier function and increase antigen uptake. Aqueous pollen extract proteins and pollen lipids modulate dendritic cell function and induce Th2 polarization. Clinical studies have shown that modulation of innate immune response to pollens with toll-like receptor 9- and toll-like receptor 4-stimulating conjugates is well tolerated and induces clear immunological effects, but is not very effective in suppressing primary clinical endpoints of allergic inflammation.

SUMMARY

Additional research on innate immune pathways induced by pollen components is required to develop novel strategies that will mitigate the development of allergic inflammation.

Non-allergenic factors from pollen modulate T helper cell instructing notch ligands on dendritic cells

BACKGROUND

Pollen allergens are delivered to epithelial surfaces of the upper respiratory tract in conjunction with multiple endogenous adjuvants. We previously demonstrated pollen-mediated modulation of cytokine and chemokine production of dendritic cells, contributing to a Th2-dominated micromilieu. As T helper cell differentiation not only depends on dendritic cell-derived cytokines but also on cell-cell-contact mediated mechanisms, we studied the expression of notch ligands and myeloid differentiation primary response protein 88 (MyD88) in dendritic cells matured in the presence of aqueous birch pollen extracts and pollen-associated E1-phytoprostanes.

METHODS

Human monocyte-derived dendritic cells were stimulated with aqueous birch pollen extracts in the absence or presence of lipopolysaccharide, and mRNA expression levels of notch ligands delta-1 and -4, jagged-1 and -2 and of myd88 were determined. Regulation of Delta-4 and MyD88 by aqueous pollen extracts was assessed on protein level. The contribution of notch signaling to T helper cell differentiation was analyzed in allogeneic T cell stimulation assays.

RESULTS

In immature dendritic cells, stimulation with pollen extracts resulted in an induction of both delta and jagged notch ligands. The lipopolysaccharide-induced up-regulation of delta-1 and -4 and of myd88 was decreased by aqueous pollen extracts, whereas jagged expression was induced. Reduction of Delta-4 and MyD88 by aqueous pollen extracts was confirmed on protein level. The Th2-skewing activity was contained in a fraction of aqueous pollen extracts enriched for molecules <3 kDa and was distinct from the previously identified E1-phytoprostanes. Reduction of notch signaling in dendritic cells matured in the presence aqueous pollen extract leads to inhibition of IL-10 and to induction of IL-5 production in naïve T cells differentiated by these dendritic cells.

CONCLUSIONS

Pollen derived, non-allergenic factors reduce the dendritic cell's expression of Th1 instructing Delta-like notch ligands and of MyD88, thereby promoting Th2 skewing of T helper cell responses.

Medicinal plants of the genus Betula--traditional uses and a phytochemical-pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Trees and shrubs of the genus Betula (Betulaceae) inhabit various ecosystems in temperate and boreal climate zones of the northern hemisphere. The healing properties of Betula bark and bark extracts have been known for a long time in traditional medicine in different parts of the world. Several species of Betula have traditionally been used for the treatment of various inflammatory diseases including arthritis. The purpose of this review is to provide updated, comprehensive and categorized information on the botany, traditional uses, phytochemistry and pharmacological and toxicological research of Betula species in order to explore their therapeutic potential and evaluate future research opportunities.

MATERIALS AND METHODS

All the available information on various species belonging to the genus Betula was collected via electronic search (using Pubmed, SciFinder, Scirus, Google Scholar, JCCC@INSTIRC and Web of Science) and a library search for articles published in peer-reviewed journals.

RESULTS

Although over a hundred Betula species are found distributed globally, about 7 different species of Betula have been documented for their traditional uses. Phytochemical research on Betula species has led to the isolation of triterpenoids, diarylheptanoids, phenylbutanoids, lignans, phenolics and flavonoids. Crude extracts, fractions and phytochemical constituents isolated from Betula showed a wide spectrum of in vitro and in vivo pharmacological activities like immunomodulatory, anti-inflammatory, antimicrobial, antiviral, antioxidant, antidiabetic, dermatological, gastroprotective and hepatoprotective. Antiarthritic and anticancer are the two major areas of research conducted on these species. The anti-carcinogenic effects of Betula bark, betulin as well as betulinic acid have been extensively studied.

CONCLUSIONS

Several species belonging to the genus Betula are widely used in traditional medicine. Betula platyphylla and Betula pendula have specifically been found to be potentially useful in the treatment of degenerative joint disease. There is convincing evidence in experimental animal models in support of their anti-carcinogenic effects. However, it would be worthwhile to investigate the biochemical and physiological mechanisms as well as detailed preclinical toxicity, bioavailability, pharmacokinetics and pharmacodynamics of the different biologically active extracts as well as molecules in sufficient detail. An integrated and holistic approach is required for tapping the full potentials of this important genus.

The environment-pathogen-host axis in communicable and non-communicable diseases: recent advances in experimental and clinical research

Allergies and autoimmune diseases are spreading worldwide. Control of infections, on the other hand, remains an issue, even in the post-antibiotic era. Chronic or poorly controlled infections occur in immune compromised individuals such as HIV patients, hospitalized patients exposed to multi-resistant bacteria, or patients on immunosuppressive treatment. They may become an even more emerging issue in an ageing population. At the same time, profound environmental changes such as global warming, urbanization, increasing environmental pollution and novel food engineering technologies may alter the abundance or aggressiveness of allergens/allergen carriers in our environment. Likewise, changes in dietary habits - and possibly also use of antibiotics - have an impact on the composition of our natural microbial flora in the gut, airways and skin, which may alter susceptibility for common diseases, among them allergies, asthma and atopic eczema. At the recently founded Institute of Environmental Medicine of the Technische Universität Munich, located in Augsburg at the UNIKA-T, experimental, clinical and translational research is focused on the complex interactions of environment, pathogen and host in expression or control of communicable and non-communicable diseases. We present our research concept and recent findings in environment - host interactions.

Novel allergic asthma model demonstrates ST2-dependent dendritic cell targeting by cypress pollen

BACKGROUND

Cypress pollen causes respiratory syndromes with different grades of severity, including asthma. IL-33, its receptor ST2, and dendritic cells (DCs) have been implicated in human respiratory allergy.

OBJECTIVE

We sought to define a new mouse model of allergy to cypress pollen that recapitulates clinical parameters in allergic patients and to evaluate the implications of DCs and the IL-33/ST2 pathway in this pathology.

METHODS

BALB/c mice, either wild-type or ST2 deficient (ST2(-/-)), were sensitized and challenged with the Cupressus arizonica major allergen nCup a 1. Local and systemic allergic responses were evaluated. Pulmonary cells were characterized by means of flow cytometry. DCs were stimulated with nCup a 1 and tested for their biological response to IL-33 in coculture assays.

RESULTS

nCup a 1 causes a respiratory syndrome closely resembling human pollinosis in BALB/c mice. nCup a 1-treated mice exhibit the hallmarks of allergic pathology associated with pulmonary infiltration of eosinophils, T cells, and DCs and a dominant TH2-type immune response. IL-33 levels were increased in lungs and sera of nCup a 1-treated mice and in subjects with cypress allergy. The allergen-specific reaction was markedly reduced in ST2(-/-) mice, which showed fewer infiltrating eosinophils, T cells, and DCs in the lungs. Finally, stimulation of DCs with nCup a 1 resulted in ST2 upregulation that endowed DCs with increased ability to respond to IL-33-mediated differentiation of IL-5- and IL-13-producing CD4 T cells.

CONCLUSIONS

Our findings define a novel preclinical model of allergy to cypress pollen and provide the first evidence of a functionally relevant linkage between pollen allergens and TH2-polarizing activity by DCs through IL-33/ST2.

100 years of hyposensitization: history of allergen-specific immunotherapy (ASIT)

Hundred years ago, Leonhard Noon and John Freeman published their pioneering works on allergen-specific immunotherapy (ASIT) using grass pollen extracts. To honor their contribution to the development of ASIT as the only causal treatment of IgE-mediated allergies, we review the history of ASIT that started with the anecdotal descriptions of ASIT performed by the ancient king Mithridates (132-63 B.C.) and Jenner's development of a cowpox vaccine. Following Noon's and Freeman's first controlled human trials, ASIT was performed by a large number of modalities and with a myriad of pharmacologic preparations. These developments range from early aqueous pollen extracts and whole bee extracts to chemically modified allergens (allergoids) and various recombinant allergens. In addition to allergen-specific immunotherapy, non-specific immune response modifiers have been used in the past or are in the developmental stage. Also, currently many innovative experimental approaches of ASIT are studied in animal models and human in vitro systems and will hopefully further broaden the range of allergies that can be treated by ASIT, with enhanced efficacy and further reduced side-effects.

Pollen metabolome analysis reveals adenosine as a major regulator of dendritic cell-primed T(H) cell responses

BACKGROUND

Water-soluble components from pollen modulate dendritic cell (DC) functions, such as IL-12 secretion and 3'-5'-cyclic adenosine monophosphate (cAMP) signaling and migration, possibly contributing to the establishment of a T(H)2-dominated immune response against pollen. Because these effects could not solely be attributed to the previously identified pollen-associated lipid mediators, the pollen metabolome was analyzed for candidate immunomodulatory substances.

OBJECTIVE

We sought to perform an analysis of the effect of pollen-associated adenosine on DC function and T(H) cell differentiation.

METHODS

Fractions of aqueous pollen extracts (APEs) were generated by means of ultrafiltration and were subjected simultaneously to biological tests and metabolome analysis (ultra-high-resolution mass spectrometry) and ultraperformance liquid chromatography. Effects of pollen-derived adenosine on monocyte-derived DC cAMP signaling, cytokine response, and capacity to differentiate T(H) cells were studied.

RESULTS

The less than 3-kd fraction of APEs comprised thousands of substances, including adenosine in micromolar concentrations. Pollen-derived adenosine mediated A₂ receptor-dependent induction of cAMP and inhibition of IL-12p70 in DCs. APEs digested with adenosine deaminase failed to mediate IL-12 inhibition. DCs of nonatopic donors exposed to APEs showed an adenosine-dependent reduced capacity to differentiate T(H)1 cells and an enhanced capacity to induce regulatory T cells and IL-10. DCs of atopic donors failed to induce IL-10 but instead induced IL-5 and IL-13.

CONCLUSION

This study identifies adenosine out of thousands of metabolites as a potent immunoregulatory substance in pollen. It acts on the level of the DC, with differential effects in atopic and nonatopic donors.

Arabinogalactan isolated from cowshed dust extract protects mice from allergic airway inflammation and sensitization

BACKGROUND

Extract from cowshed dust (CDE) is a source of immunomodulating substances. We have previously shown that such substances protect from experimental allergic disorders in a mouse model of asthma.

OBJECTIVE

The objective of this study was to identify immunomodulatory molecules in extracts of dust from an allergy protective farming environment.

METHODS

Polysaccharides were isolated from CDE and plants by chromatography and precipitation with specific reagents. Polysaccharides were then characterized by nuclear magnetic resonance spectroscopy. Subsequently, the allergy-protective potential of isolated polysaccharides was tested in a mouse model of asthma.

RESULTS

The authors demonstrate that plant arabinogalactans are contained in CDE in high concentrations. The source of this arabinogalactan is fodder, in particular a prevalent grass species known as Alopecurus pratensis. Treatment of murine dendritic cells with grass arabinogalactan resulted in autocrine IL-10 production. Interestingly, these dendritic cells were not able to induce an allergic immune response. Furthermore, intranasal application of grass arabinogalactan protected mice from developing atopic sensitization, allergic airway inflammation and airway hyperreactivity in a mouse model of allergic asthma. This allergy-protective effect is specific for grass arabinogalactan because control experiments with arabinogalactan from gum arabic and larch revealed that these molecules do not show allergy-protective properties. This is likely because of structural differences because we were able to show by nuclear magnetic resonance spectroscopy that although they are predominantly composed of arabinose and galactose, the molecules differ in structure.

CONCLUSIONS

The authors conclude that grass arabinogalactans are important immunomodulatory substances that contribute to the protection from allergic airway inflammation, airway hyperresponsiveness, and atopic sensitization in a mouse model of asthma.

Pollen-derived low-molecular weight factors inhibit 6-sulfo LacNAc+ dendritic cells' capacity to induce T-helper type 1 responses

BACKGROUND

Evidence is accumulating that the pollen exsudate contains an array of non-allergenic, pro-inflammatory and immunomodulatory substances acting on the innate and adaptive immune system. In this context, pollen-associated E(1)-phytoprostanes (PPE(1)) were shown to licence human monocyte-derived dendritic cells for T-helper type 2 (Th2) polarization of naïve T cells.

OBJECTIVE

This study aims at analysing the impact of pollen-associated lipid mediators on cytokine secretion and maturation of 6-sulfo LacNAc(+) dendritic cells (slanDCs), the most abundant native dendritic cell (DC) in human peripheral blood, and further dissecting the biologically active substance(s) within aqueous pollen extracts.

RESULTS

Aqueous birch pollen extracts dose-dependently inhibited the lipopolysaccharide (LPS)-induced IL-12 p70 production, while the levels of IL-6 remained unaffected. PPE(1) inhibited secretion of both IL-12 p70 and IL-6. Aqueous pollen extracts, but not PPE(1) or F(1)-phytoprostanes significantly reduced the LPS-induced surface expression of the maturation markers CD80, CD83, CD40 and CCR-7, an effect that was independent of proteins and that was still present in a 3 kDa cut-off fraction of the pollen extract. These effects were observed irrespective of the atopy status of the donors. Finally, slanDCs exposed to aqueous pollen extracts were impaired in eliciting an IFN-gamma response in naïve CD4(+) T cells.

CONCLUSION

Our data show that slanDCs, a subset of human blood DCs with constitutively high potency to induce Th1 responses, are susceptible to the Th2 polarizing effect of low molecular weight, non-protein factors derived from pollen.

Antigen-specific immunotherapy against allergic rhinitis: the state of the art

Allergic rhinitis is the most prevalent type I allergy in industrialized countries. Pollen scattering from trees or grasses often induces seasonal allergic rhinitis, which is known as pollinosis or hay fever. The causative pollen differs across different areas and times of the year. Impaired performance due to pollinosis and/or medication used for treating pollinosis is considered to be an important reason for the loss of concentration and productivity in the workplace. Antigen-specific immunotherapy is an only available curative treatment against allergic rhinitis. Subcutaneous injection of allergens with or without adjuvant has been commonly used as an immunotherapy; however, recently, sublingual administration has come to be considered a safer and convenient alternative administration route of allergens. In this review, we focus on the safety and protocol of subcutaneous and sublingual immunotherapy against seasonal allergic rhinitis. We also describe an approach to selecting allergens for the vaccine so as to avoid secondary sensitization and adverse events. The biomarkers and therapeutic mechanisms for immunotherapy are not fully understood. We discuss the therapeutic biomarkers that are correlated with the improvement of clinical symptoms brought about by immunotherapy as well as the involvement of Tr1 and regulatory T cells in the therapeutic mechanisms. Finally, we focus on the current immunotherapeutic approach to treating Japanese cedar pollinosis, the most prevalent pollinosis in Japan, including sublingual immunotherapy with standardized extract, a transgenic rice-based edible vaccine, and an immunoregulatory liposome encapsulating recombinant fusion protein.

Exposure to mycotoxins increases the allergic immune response in a murine asthma model

RATIONALE

Epidemiological studies have shown that indoor molds are associated with increased prevalence and exacerbation of respiratory symptoms and asthma. Mycotoxins, secondary metabolites of molds, may contribute to these effects.

OBJECTIVES

To investigate the adjuvant activity of mycotoxins on allergic airway inflammation.

METHODS

Balb/c mice were exposed via the airways to gliotoxin and via the intestine to patulin, sensitized with ovalbumin (OVA), and then analyzed in acute and chronic murine asthma models. In addition, the effect of mycotoxin exposure on dendritic cell (DC) function was investigated using murine bone marrow-derived DCs.

MEASUREMENTS AND MAIN RESULTS

Exposure of mice to both mycotoxins enhanced dose-dependently airway hyperreactivity, eosinophilic lung inflammation, and OVA-specific IgE serum levels compared with mice that received only the antigen. These findings correlated with increased Th2 cytokine levels and decreased IFN-gamma production. Long-term mycotoxin exposure exacerbated chronic airway inflammation and airway remodeling. In vitro or in vivo mycotoxin exposure inhibited IL-12 production in maturing DCs and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. Mycotoxin exposure enhanced OVA-induced lung lipid peroxidation and moderately increased isoprostane levels in naive mice. Treatment of mycotoxin-exposed DCs with the antioxidants N-acetylcysteine or glutathione ethyl ester restored IL-12 secretion and pretreatment of exposed mice with N-acetylcysteine prevented the mycotoxin-induced increase of airway inflammation and AHR.

CONCLUSIONS

Our results demonstrate that gliotoxin and patulin increase the allergic immune response in mice by modulating the Th1/Th2 balance via direct effects on IL-12 secretion in DCs and by inducing oxidative stress.

Pollen-induced oxidative stress influences both innate and adaptive immune responses via altering dendritic cell functions

It has been demonstrated that pollen grains contain NAD(P)H oxidases that induce oxidative stress in the airways, and this oxidative insult is critical for the development of allergic inflammation in sensitized mice. On the basis of this observation, we have examined whether pollen grain exposure triggers oxidative stress in dendritic cells (DCs), altering their functions. To test this hypothesis, human monocyte-derived DCs were treated with ragweed pollen grains. Our findings show that exposure to pollen grains induces an increase in the intracellular levels of reactive oxygen species in DCs. Our data also indicate that besides the NAD(P)H oxidases, other component(s) of pollen grains contributes to this phenomenon. Elevated levels of intracellular reactive oxygen species triggered the production of IL-8 as well as proinflammatory cytokines, such as TNF-alpha and IL-6. Treatment with pollen grains initiated the maturation of DCs, strongly upregulated the membrane expression of CD80, CD86, CD83, and HLA-DR, and caused only a slight increase in the expression of CD40. The pollen-treated DCs induced the development of naive T lymphocytes toward effector T cells with a mixed profile of cytokine production. Antioxidant inhibited both the phenotypic and functional changes of DCs, underlining the importance of oxidative stress in these processes. Collectively, these data show that pollen exposure-induced oxidative stress may contribute to local innate immunity and participate in the initiation of adaptive immune responses to pollen Ags.

Cupressaceae pollen grains modulate dendritic cell response and exhibit IgE-inducing adjuvant activity in vivo

Pollen is considered a source of not only allergens but also immunomodulatory substances, which could play crucial roles in sensitization and/or the exacerbation of allergies. We investigated how allergenic pollens from different plant species (Japanese cedar and Japanese cypress, which belong to the Cupressaceae family, and birch, ragweed, and grass) modulate murine bone marrow-derived dendritic cell (DC) responses and examined the effect of Cupressaceae pollen in vivo using mice. DCs were stimulated with pollen extracts or grains in the presence or absence of LPS. Cell maturation and cytokine production in DCs were analyzed by flow cytometry, ELISA, and/or quantitative PCR. Pollen extracts suppressed LPS-induced IL-12 production and the effect was greatest for birch and grass. Without LPS, pollen grains induced DC maturation and cytokine production without IL-12 secretion and the response, for which TLR 4 was dispensable, was greatest for the Cupressaceae family. Intranasal administration of Cupressaceae pollen in mice induced an elevation of serum IgE levels and airway eosinophil infiltration. Coadministration of ovalbumin with Cupressaceae pollen grains induced ovalbumin-specific IgE responses associated with eosinophil infiltration. The results suggest that modulation of DC responses by pollen differs among the plant families via (1) the promotion of DC maturation and cytokine production by direct contact and/or (2) the inhibition of IL-12 production by soluble factors. The strong DC stimulatory activity in vitro and IgE-inducing activity in mice support the clinical relevance of Cupressaceae pollen to allergies in humans.

Pollen allergens do not come alone: pollen associated lipid mediators (PALMS) shift the human immune systems towards a T(H)2-dominated response

Pollen allergy is characterized by a T(H)2-biased immune response to pollen-derived allergens. However, pollen-exposed epithelia do not encounter pure allergen but rather a plethora of protein and non-protein substances. We demonstrated that pollen liberate lipids with chemical and functional similarities to leukotriens and prostaglandins--the pollen associated lipid mediators (PALMs). To date, two main groups of PALMs have been characterized: The immunostimulatory PALMs activating innate immune cells such as neutrophils and eosinophils, and the immunomodulatory E(1)-phytoprostanes blocking IL-12 production of dendritic cells, resulting in the preferential induction of T(H)2 responses. This article reviews our work in the field of PALMs and their effects on cells of the innate and adoptive immune system. From recent results a general picture starts to emerge in which PALMs (and possibly other pollen-associated substances) may--independently from protein allergens--propagate an overall T(H)2 favoring micromilieu in pollen exposed tissue of predisposed individuals.

Flaxseed oil supplementation increases plasma F1-phytoprostanes in healthy men

Supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been reported to reduce lipid peroxidation products formed from arachidonic acid (F(2)-isoprostanes) in healthy humans, as well as in those under oxidative stress. alpha-Linolenic acid (ALA) is a precursor to EPA and DHA; however, its conversion in humans is thought to be inefficient. ALA can also undergo free radical oxidation, forming compounds known as F(1)-phytoprostanes, which are found in all plants and are in high concentrations in plant pollens. In this study, we examined the effect of ALA supplementation on plasma and urine F(1)-phytoprostane and F(2)-isoprostane concentrations in men. Thirty-six nonsmoking men, aged 20-65 y, were recruited from the general population and randomly allocated to consume 9 g/d of either flaxseed oil (62% ALA, 5.4 g/d) or olive oil (placebo) for 4 wk in a parallel design. At baseline and after 4 wk of supplementation, blood samples and a 24-h urine sample were collected for measurement of plasma and urinary F(1)-phytoprostanes and F(2)-isoprostanes and plasma fatty acids. Compared with the olive oil group, plasma phospholipid ALA was greater (P < 0.0001), as were F(1)-phytoprostanes in plasma (P = 0.049) and urine (P = 0.06) in the flaxseed oil group after 4 wk supplementation. Flaxseed oil did not affect plasma or urinary F(2)-isoprostanes. The greater plasma F(1)-phytoprostane concentration in the flaxseed oil group most likely resulted from the increased plasma concentration of the ALA substrate and/or the F(1)-phytoprostane content of the flaxseed oil. Future studies are needed to determine the physiological importance of increased plasma and urine F(1)-phytoprostanes and their relevance to heart disease prevention.

New bioactive oxylipins formed by non-enzymatic free-radical-catalyzed pathways: the phytoprostanes

In animals and plants, fatty acids with at least three double bonds can be oxidized to prostaglandin-like compounds via enzymatic and non-enzymatic pathways. The most common fatty acid precursor in mammals is arachidonic acid (C20:4) (AA) which can be converted through the cyclooxygenase pathway to a series of prostaglandins (PG). Non-enzymatic cyclization of arachidonate yields a series of isoprostanes (IsoP) which comprises all PG (minor compounds) as well as PG isomers that cannot be formed enzymatically. In contrast, in plants, alpha-linolenic acid (C18:3) (ALA) is the most common substrate for the allene oxide synthase pathway leading to the jasmonate (JA) family of lipid mediators. Non-enzymatic oxidation of linolenate leads to a series of C18-IsoPs termed dinor IsoP or phytoprostanes (PP). PP structurally resemble JA but cannot be formed enzymatically. We will give an overview of the biological activity of the different classes of PP and also discuss their analytical applications and the strategies developed so far for the total synthesis of PP, depending on the synthetic approaches according to the targets and which key steps serve to access the natural products.

Pollen-derived E1-phytoprostanes signal via PPAR-gamma and NF-kappaB-dependent mechanisms

In a humid milieu such as mucosal surfaces, pollen grains do not only release allergens but also proinflammatory and immunomodulatory lipids, termed pollen-associated lipid mediators. Among these, the E(1)-phytoprostanes (PPE(1)) were identified to modulate dendritic cell (DC) function: PPE(1) inhibit the DC's capacity to produce IL-12 and enhance DC mediated T(H)2 polarization of naive T cells. The mechanism(s) by which PPE(1) act on DC remained elusive. We thus analyzed candidate signaling elements and their role in PPE(1)-mediated regulation of DC function. Aqueous birch pollen extracts induced a marked cAMP response in DC that could be blocked partially by EP2 and EP4 antagonists. In contrast, PPE(1) hardly induced cAMP and the inhibitory effect on IL-12 production was mostly independent of EP2 and EP4. Instead, PPE(1) inhibited the LPS-induced production of IL-12 p70 by a mechanism involving the nuclear receptor PPAR-gamma. Finally, PPE(1) efficiently blocked NF-kappaB signaling in DCs by inhibiting IkappaB-alpha degradation, translocation of p65 to the nucleus, and binding to its target DNA elements. We conclude that pollen-derived PPE(1) modulate DC function via PPAR-gamma dependent pathways that lead to inhibition of NFkappaB activation and result in reduced DC IL-12 production and consecutive T(H)2 polarization.