The anti-inflammatory sesquiterpene lactone parthenolide suppresses IL-4 gene expression in peripheral blood T

Exploring the Phytochemistry, Signaling Pathways, and Mechanisms of Action of Tanacetum parthenium (L.) Sch.Bip.: A Comprehensive Literature Review

The traditional use of Tanacetum parthenium (L.) Sch.Bip., commonly known as feverfew, extends across various medical conditions, notably those associated with pain and inflammation. In alignment with the growing trend towards developing medications that target specific signaling pathways for enhanced efficacy and reduced side effects, extensive research has been conducted to investigate and validate the pharmacological effects of feverfew. Among its bioactive compounds, parthenolide stands out as the most potent, categorized as a germacranolide-type sesquiterpene lactone, and has been extensively studied in multiple investigations. Significantly, the anti-inflammatory properties of feverfew have been primarily attributed to its capacity to inhibit nuclear factor-kappa B (NF-κB), resulting in a reduction in pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-α). Furthermore, the anticancer properties of feverfew have been associated with the modulation of Mitogen-Activated Protein Kinase (MAPK) and NF-κB signaling pathways. This study further delves into the neuroprotective potential of feverfew, specifically in the management of conditions such as migraine headaches, epilepsy, and neuropathic pain through various mechanisms. The core objective of this study is to elucidate the phytochemical composition of feverfew, with a particular emphasis on understanding the molecular mechanisms and examining the signaling pathways that contribute to its pharmacological and therapeutic effects. Additionally, the safety, toxicity, and potential adverse effects of feverfew are comprehensively evaluated, with an overarching goal of providing valuable insights into the plant's potential for targeted and effective treatments.

A Comparison between Bulgarian Tanacetum parthenium Essential Oil from Two Different Locations

Tanacetum parthenium L. (Asteraceae) is a perennial herbaceous plant with a long-standing historical use in traditional medicine. Recently Tanacetum parthenium L. essential oil has been associated with a promising potential for future applications in the pharmaceutical industry, in the cosmetics industry, and in agriculture. Investigations on the essential oil (EO) have indicated antimicrobial, antioxidant, and repellent activity. The present study aimed to evaluate the chemical composition of Bulgarian T. parthenium essential oil from two different regions, to compare the results to those reported previously in the literature, and to point out some of its future applications. The essential oils of the air-dried flowering aerial parts were obtained by hydrodistillation using a Clevenger-type apparatus. The chemical composition was evaluated using gas chromatography with mass spectrometry (GC-MS). It was established that the oxygenated monoterpenes were the predominant terpene class, followed by the monoterpene hydrocarbons. Significant qualitative and quantitative differences between both samples were revealed. Camphor (50.90%), camphene (16.12%), and bornyl acetate (6.05%) were the major constituents in the feverfew EO from the western Rhodope Mountains, while in the EO from the central Balkan mountains camphor (45.54%), trans-chrysanthenyl acetate (13.87%), and camphene (13.03%) were the most abundant components.

In Vitro Evaluation of Ferutinin Rich-Ferula communis L., ssp. glauca, Root Extract on Doxorubicin-Induced Cardiotoxicity: Antioxidant Properties and Cell Cycle Modulation

The clinical use of anthracycline Doxorubicin as an antineoplastic drug in cancer therapy is limited by cardiotoxic effects that can lead to congestive heart failure. Recent studies have shown several promising activities of different species of the genus Ferula belonging to the Apiaceae Family. Ferula communis is the main source of Ferutinin-a bioactive compound isolated from many species of Ferula-studied both in vitro and in vivo because of their different effects, such as estrogenic, antioxidant, anti-inflammatory, and also antiproliferative and cytotoxic activity, performed in a dose-dependent and cell-dependent way. However, the potential protective role of Ferutinin in myocardium impairment, caused by chemotherapeutic drugs, still represents an unexplored field. The aim of this study was to test the effects of Ferutinin rich-Ferula communis L. root extract (FcFE) at different concentrations on H9C2 cells. Moreover, we evaluated its antioxidant properties in cardiomyocytes in order to explore new potential therapeutic activities never examined before in other experimental works. FcFE, at a concentration of 0.25 µM, in the H9C2 line, significantly reduced the ROS production induced by H2O2 (50 µM and 250 µM) and traced the cell mortality of the H9C2 co-treated with Ferutinin 0.25 µM and Doxorubicin (0.5 µM and 1 µM) to control levels. These results showed that FcFE could protect against Doxorubicin-induced cardiotoxicity. Further molecular characterization of this natural compound may open the way for testing FcFE at low concentrations in vivo and in clinical studies as an adjuvant in cancer therapy in association with anthracyclines to prevent side effects on heart cells.

Chicory Extracts and Sesquiterpene Lactones Show Potent Activity against Bacterial and Fungal Pathogens

Chicory (Cichorium intybus L.) is an important industrial crop cultivated mainly to extract the dietary fiber inulin. However, chicory also contains bioactive compounds such as sesquiterpene lactones and certain polyphenols, which are currently discarded as waste. Plants are an important source of active pharmaceutical ingredients, including novel antimicrobials that are urgently needed due to the global spread of drug-resistant bacteria and fungi. Here, we tested different extracts of chicory for a range of bioactivities, including antimicrobial, antifungal and cytotoxicity assays. Antibacterial and antifungal activities were generally more potent in ethyl acetate extracts compared to water extracts, whereas supercritical fluid extracts showed the broadest range of bioactivities in our assays. Remarkably, the chicory supercritical fluid extract and a purified fraction thereof inhibited both methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin-resistant Pseudomonas aeruginosa IBRS P001. Chicory extracts also showed higher antibiofilm activity against the yeast Candida albicans than standard sesquiterpene lactone compounds. The cytotoxicity of the extracts was generally low. Our results may thus lead to the development of novel antibacterial and antifungal preparations that are both effective and safe for human use.

The Effect of Ferula communis Extract in Escherichia coli Lipopolysaccharide-Induced Neuroinflammation in Cultured Neurons and Oligodendrocytes

In recent decades, interest in natural compounds has increased exponentially due to their numerous beneficial properties in the treatment of various acute and chronic diseases. A group of plant derivatives with great scientific interest is terpenic compounds. Among the plants richest in terpenes, the genus Ferula L. is one of the most representative, and ferutinin, the most common sesquiterpene, is extracted from the leaves, rhizome, and roots of this plant. As reported in the scientific literature, ferutinin possesses antioxidant and anti-inflammatory properties, as well as valuable estrogenic properties. Neurodegenerative and demyelinating diseases are devastating conditions for which a definite cure has not yet been established. The mechanisms involved in these diseases are still poorly understood, and oxidative stress is considered to be both a key modulator and a common denominator. In the proposed experimental system, co-cultured human neurons (SH-SY5Y) and human oligodendrocytes (MO3.13) were treated with the pro-inflammatory agent lipopolysaccharide at a concentration of 1 μg/mL for 24 h or pretreated with ferutinin (33 nM) for 24 h and subsequently exposed to lipopolysaccharide 1 μg/mL for 24 h. Further studies would, however, be needed to establish whether this natural compound can be used as a support strategy in pathologies characterized by progressive inflammation and oxidative stress phenomena.

Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.

Ferula L. Plant Extracts and Dose-Dependent Activity of Natural Sesquiterpene Ferutinin: From Antioxidant Potential to Cytotoxic Effects

The employment studies of natural extracts in the prevention and treatment of several diseases highlighted the role of different species of genus Ferula L., belonging to the Apiaceae family, dicotyledonous plants present in many temperate zones of our planet. Ferula communis L. is the main source of sesquiterpene ferutinin, a bioactive compound studied both in vitro and in vivo, because of different effects, such as phytoestrogenic, antioxidant, anti-inflammatory, but also antiproliferative and cytotoxic activity, performed in a dose-dependent and cell-dependent way. The present review will focus on the molecular mechanisms involved in the different activities of Ferutinin, starting from its antioxidant potential at low doses until its ionophoric property and the subsequent mitochondrial dysfunction induced through administration of high doses, which represent the key point of its anticancer action. Furthermore, we will summarize the data acquired from some experimental studies on different cell types and on several diseases. The results obtained showed an important antioxidant and phytoestrogenic regulation with lack of typical side effects related to estrogenic therapy. The preferential cell death induction for tumor cell lines suggests that ferutinin may have anti-neoplastic properties, and may be used as an antiproliferative and cytotoxic agent in an estrogen dependent and independent manner. Nevertheless, more data are needed to clearly understand the effect of ferutinin in animals before using it as a phytoestrogen or anticancer drug.

Deciphering morpho-physiological and phytochemical attributes of Tanacetum parthenium L. plants exposed to C60 fullerene and salicylic acid

This study was aimed to evaluate the effects of C60 fullerene concentrations (0, 125, 250, 500 and 1000 mg/L) and salicylic acid (0 and 0.2 mM) on growth and phytochemical accumulation of two feverfew genotypes (Pharmasaat and Jelitto) in a factorial experiment based on completely randomized design with three replications. According to the ANOVA, triple interaction of treatments were significant on morphological and phytochmical traits, however, the main effect of treatments only affected physiological attributes. Application of salicylic acid differentially influenced the effects of various concentrations of C60 fullerene on growth traits of both genotypes. In Pharmasaat, foliar application of salicylic acid increased growth traits of plants exposed to C60 fullerene at all concentrations, however, it improved the growth of Jelitto at higher levels of fullerene. The maximum increase of flower + leaf dry weight was recorded at 1000 mg/L C60 fullerene in combination with salicylic acid compared to control for Jelitto. In Pharmasaat, the parthenolide content significantly increased following increase of C60 fullerene up to 250 mg/L with salicylic acid, but a rapid decrease followed at 500-1000 mg/L. SEM images showed a wider deposition (many spheres with different sizes) of C60 fullerene on leaf tissue of Pharmasaat exposed to high concentration, involving changes in trichome density and tissue rupture. The essential oil content was not significantly increased upon experimental treatments compared to control. Based on hierarchical cluster analysis, C60 fullerene and salicylic acid treatments caused to a co-induction of ion leakage, chlorophyll a, essential oil and parthenoloide in Pharmasaat.

The natural sesquiterpene lactones arglabin, grosheimin, agracin, parthenolide, and estafiatin inhibit T cell receptor (TCR) activation

Inhibition of the T cell receptor (TCR) pathway represents an effective strategy for the treatment of T cell-mediated inflammatory and autoimmune diseases. To identify natural compounds that could inhibit inflammatory T cell responses, we screened 13 sesquiterpene lactones, including achillin, arglabin, argolide, argracin, 3β-hydroxyarhalin, artesin, artemisinin, estafiatin, grosheimin, grossmisin, leucomisine, parthenolide, and taurine, for their ability to modulate activation-induced Ca²⁺ mobilization in Jurkat T cells. Five of the compounds (arglabin, grosheimin, argracin, parthenolide, and estafiatin) inhibited anti-CD3-induced mobilization of intercellular Ca²⁺ ([Ca²⁺]_i) in Jurkat cells, with the most potent being parthenolide and argacin (IC₅₀ = 5.6 and 6.1 μM, respectively). Likewise, phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in activated Jurkat cells was inhibited by these five compounds, with the most potent being parthenolide and estafiatin (IC₅₀ = 13.8 and 15.4 μM, respectively). These compounds also inhibited ERK1/2 phosphorylation in primary human T cells and depleted intracellular glutathione. In contrast, none of the sesquiterpene lactones inhibited ERK1/2 phosphorylation in HL60 cells transfected with N-formyl peptide receptor 2 (FPR2) and stimulated with the FPR2 peptide agonist WKYMVM, indicating specificity for T cell activation. Estafiatin, a representative sesquiterpene lactone, was also profiled in a cell-based phosphokinase array for 43 kinase phosphorylation sites, as well as in a cell-free competition binding assay for its ability to compete with an active-site directed ligand for 95 different protein kinases. Besides inhibition of ERK1/2 phosphorylation, estafiatin also inhibited phosphorylation of p53, AMPKα1, CREB, and p27 elicited by TCR activation in Jurkat cells, but it did not bind to any of 95 kinases evaluated. These results suggest that arglabin, grosheimin, agracin, parthenolide, and estafiatin can selectively inhibit initial phases of TCR activation and may be natural compounds with previously undescribed immunotherapeutic properties.

Identification and characterization of two bisabolene synthases from linear glandular trichomes of sunflower (Helianthus annuus L., Asteraceae)

Sunflower is known to produce a variety of bisabolene-type sesquiterpenes and accumulates these substances in trichomes of leaves, stems and flowering parts. A bioinformatics approach was used to identify the enzyme responsible for the initial step in the biosynthesis of these compounds from its precursor farnesyl pyrophosphate. Based on sequence similarity with a known bisabolene synthases from Arabidopsis thaliana AtTPS12, candidate genes of Helianthus were searched in EST-database and used to design specific primers. PCR experiments identified two candidates in the RNA pool of linear glandular trichomes of sunflower. Their sequences contained the typical motifs of sesquiterpene synthases and their expression in yeast functionally characterized them as bisabolene synthases. Spectroscopic analysis identified the stereochemistry of the product of both enzymes as (Z)-γ-bisabolene. The origin of the two sunflower bisabolene synthase genes from the transcripts of linear trichomes indicates that they may be involved in the synthesis of sesquiterpenes produced in these trichomes. Comparison of the amino acid sequences of the sunflower bisabolene synthases showed high similarity with sesquiterpene synthases from other Asteracean species and indicated putative evolutionary origin from a β-farnesene synthase.

Sesquiterpene lactone parthenolide attenuates production of inflammatory mediators by suppressing the Toll-like receptor-4-mediated activation of the Akt, mTOR, and NF-κB pathways

Microbial product lipopolysaccharide has been shown to be involved in the pathogenesis of inflammatory skin diseases. Parthenolide present in extracts of the herb feverfew has demonstrated an anti-inflammatory effect. However, the effect of parthenolide on the Akt/mTOR and NF-κB pathway activation-induced productions of inflammatory mediators in keratinocytes has not been studied. Using human keratinocytes, we investigated the effect of parthenolide on the inflammatory mediator production in relation to the Toll-like receptor-4-mediated-Akt/mTOR and NF-κB pathways, which regulate the transcription genes involved in immune and inflammatory responses. Parthenolide, Akt inhibitor, Bay 11-7085, and N-acetylcysteine each attenuated the lipopolysaccharide-induced production of IL-1β and PGE2, increase in the levels of cyclooxygenase, formation of reactive oxygen species, increase in the levels of Toll-like receptor-4, and activation of the Akt/mTOR and NF-κB in keratinocytes. The results show that parthenolide appears to attenuate the lipopolysaccharide-stimulated production of inflammatory mediators in keratinocytes by suppressing the Toll-like receptor-4-mediated activation of the Akt, mTOR, and NF-κB pathways. The activation of signaling transduction pathways appear to be regulated by reactive oxygen species. Parthenolide appears to attenuate the microbial product-mediated inflammatory skin diseases.

The effect of 4α,5α-epoxy-10α,14-dihydro-inuviscolide, a novel immunosuppressant isolated from Carpesium abrotanoides, on the cytokine profile in vitro and in vivo

The plant Carpesium abrotanoides (CA) is used in Asian herbal medicines as an insecticide and to treat bruises. However, the effect of single compounds from CA blooms and the mechanism of its immunosuppressive effect remain poorly understood. The aim of this study was to investigate the mechanism of the immunosuppressive effect in the three kinds of immune cells, and the immunosuppressive effect of CA bloom extract (CAE) in acute inflammation models (LPS and ConA-induced inflammation). Interleukin-6, IL-4, IL-13, IFNγ, and IL-10-but not TNFα-were significantly reduced in a dose-dependent manner by 4α,5α-epoxy-10α,14-dihydro-inuviscolide (INV). Furthermore, INV inhibited NF-κB transcriptional activation and IL-10 promoter activity in the same manner as for Bay11. Meanwhile, treatment with dexamethasone reduced the levels of IFNγ, but not IL-10, and resulted in no change in NF-κB transcriptional activation or the IL-10 promoter. INV did not affect PMA-induced IκB kinase complex phosphorylation, IκB degradation, or MAPK and the nuclear translocation of p65, as with DEX. The in vivo, CAE has an immunosuppressive effect on the LPS-induced inflammation response model by inhibiting the plasma level of IFNγ and IL-6 levels. CAE treatment also tends to attenuate the plasma level of IFNγ, IL-4, and IL-6 in ConA-induced inflammation. These findings indicate that INV causes the reduction of the cytokine profile by blocking the NF-κB transcription factor activation and the molecular mechanism by which INV operates could provide new insights into the unique mechanisms responsible for NF-κB inhibition, in contrast to established immunosuppressants, as a therapeutic agent for immunopathological treatment.

Cloning of a sesquiterpene synthase from Lavandula x intermedia glandular trichomes

The essential oil (EO) of Lavandula is dominated by monoterpenes, but can also contain small amounts of sesquiterpenes, depending on species and environmental conditions. For example, the sesquiterpene 9-epi-caryophyllene can make up to 8 % of the EO in a few species, including those commercially propagated for EO production. Here, we report the cloning and functional characterization of 9-epi-caryophyllene synthase (LiCPS) from the glandular trichomes of Lavandula x intermedia, cv. Grosso. The 1,617 bp open reading frame of LiCPS, which did not encode a transit peptide, was expressed in Escherichia coli and the recombinant protein purified by Ni-NTA agarose affinity chromatography. The ca. 60 kDa recombinant protein specifically converted farnesyl diphosphate to 9-epi-caryophyllene. LiCPS also produced a few monoterpenes when assayed with the monoterpene precursor geranyl diphosphate (GPP), but--unlike most monoterpene synthases--was not able to derive detectable amounts of any products from the cis isomer of GPP, neryl diphosphate. The LiCPS transcripts accumulated in developing L. x intermedia flowers and were highly enriched in glandular trichomes, but were not detected in leaves suggesting that the transcriptional expression of this gene is spatially and developmentally regulated.

Effects of magnolialide isolated from the leaves of Laurus nobilis L. (Lauraceae) on immunoglobulin E-mediated type I hypersensitivity in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Laurus nobilis L. (Lauraceae) has been used for folk medicines in the Mediterranean area and Europe to treat various disorders including skin inflammation (dermatitis) and asthma.

AIM OF THE STUDY

Our aim was to investigate the scientific evaluation of the compounds from Laurus nobilis L. on immuniglobulin E (IgE)-mediated type I hypersensitivity responses in vitro such as atopic dermatitis and asthma.

METHODS AND MATERIALS

Seven compounds were isolated and examined for the mast cell stabilizing effect on IgE-sensitized RBL-2H3 mast cells by measuring the β-hexosaminidase activity. In addition, the effects on interleukin (IL)-4 production and IL-5-dependent Y16 early B cell proliferation were investigated as well as their cytotoxic effects on RBL-2H3 cells.

RESULTS

Among the seven isolated compounds, magnolialide attenuated the release of β-hexosaminidase from RBL-2H3 cells with an IC50 value of 20.2 μM, while the other compounds revealed no significant effects at concentrations tested. Furthermore, magnolialide significantly inhibited the IL-4 release with an IC50 value of 18.1 μM and IL-4 mRNA expression with an IC50 value of 15.7 μM in IgE-sensitized RBL-2H3 cells. In addition, the inhibition of IL-5-dependent proliferation of early B cells (Y16 cells) by magnolialide was demonstrated with an IC50 value of 18.4 μM.

CONCLUSION

These results suggest that the magnolialide might be a candidate for the treatment of IgE-mediated hypersensitivity responses such as atopic dermatitis and asthma by inhibiting mast cell degranulation, the IL-4 production, and IL-5-dependent early B cell proliferation, key factors in the development and amplification of type I hypersensitivity reactions.

The adaptor protein SAP directly associates with CD3ζ chain and regulates T cell receptor signaling

Mutations altering the gene encoding the SLAM associated protein (SAP) are responsible for the X-linked lymphoproliferative disease or XLP1. Its absence is correlated with a defective NKT cells development, a decrease in B cell functions and a reduced T cells and NK cells cytotoxic activities, thus leading to an immunodeficiency syndrome. SAP is a small 128 amino-acid long protein that is almost exclusively composed of an SH2 domain. It has been shown to interact with the CD150/SLAM family of receptors, and in a non-canonical manner with SH3 containing proteins such as Fyn, βPIX, PKCθ and Nck1. It would thus play the role of a minimal adaptor protein. It has been shown that SAP plays an important function in the activation of T cells through its interaction with the SLAM family of receptors. Therefore SAP defective T cells display a reduced activation of signaling events downstream of the TCR-CD3 complex triggering. In the present work, we evidence that SAP is a direct interactor of the CD3ζ chain. This direct interaction occurs through the first ITAM of CD3ζ, proximal to the membrane. Additionally, we show that, in the context of the TCR-CD3 signaling, an Sh-RNA mediated silencing of SAP is responsible for a decrease of several canonical T cell signaling pathways including Erk, Akt and PLCγ1 and to a reduced induction of IL-2 and IL-4 mRNA. Altogether, we show that SAP plays a central function in the T cell activation processes through a direct association with the CD3 complex.

Biosynthesis and localization of parthenolide in glandular trichomes of feverfew (Tanacetum parthenium L. Schulz Bip.)

Feverfew (Tanacetum parthenium) is a perennial medicinal herb and is a rich source of sesquiterpene lactones. Parthenolide is the main sesquiterpene lactone in feverfew and has attracted attention because of its medicinal potential for treatment of migraine and cancer. In the present work the parthenolide content in different tissues and developmental stages of feverfew was analyzed to study the timing and localization of parthenolide biosynthesis. The strongest accumulating tissue was subsequently used to isolate sesquiterpene synthases with the goal to isolate the gene encoding the first dedicated step in parthenolide biosynthesis. This led to the isolation and charachterization of a germacrene A synthase (TpGAS) and an (E)-β-caryophyllene synthase (TpCarS). Transcript level patterns of both sesquiterpene synthases were analyzed in different tissues and glandular trichomes. Although TpGAS was expressed in all aerial tissues, the highest expression was observed in tissues that contain high concentrations of parthenolide and in flowers the highest expression was observed in the biosynthetically most active stages of flower development. The high expression of TpGAS in glandular trichomes which also contain the highest concentration of parthenolide, suggests that glandular trichomes are the secretory tissues where parthenolide biosynthesis and accumulation occur.

Chemical Characterization of Magnolia Biondii (Flos Magnoliae, Xin Yi)

Samples of Magnolia biondii buds (Xin Yi, Flos Magnoliae) from different sources were subjected to phytochemical analysis and compared to samples of M. denudata and M. liliiflora. Among the compounds found in the flower buds of M. biondii were eight tetrahydrofurofuran lignans as well as the sesquiterpene lactone parthenolide and the sesquiterpene alcohol oplodiol. A rapid TLC-method for the identification of plant material from M. biondii and its distinction from M. liliiflora was developed. Structure elucidation was carried out by means of NMR (1- and 2-D) and LC-MS.

Dietary apigenin attenuates the development of atopic dermatitis-like skin lesions in NC/Nga mice

One of the flavones, apigenin has various physiological functions including anti-inflammatory activities. Atopic dermatitis (AD) is a chronically relapsing inflammatory disorder that is characterized by pruritic and eczematous skin lesions. To evaluate the anti-allergic effect of apigenin in vivo, we examined the effect of dietary apigenin on picrylchloride (PiCl)-induced AD-like pathology in NC/Nga mice. NC/Nga mice were fed experimental diets containing apigenin from Day 18 after sensitized with PiCl for 4 weeks. Dietary apigenin significantly alleviated the development of skin lesions, accompanied by lower serum immunoglobulin (Ig) G1 and IgE levels in NC/Nga mice. Interferon (IFN)-gamma mRNA expression level in spleen cells from NC/Nga mice was reduced by apigenin feeding. Moreover, interleukin 4-induced signal transducers and activators of transcription 6 phosphorylation in primary spleen cells from BALB/c mice was inhibited by treatment with apigenin. These results suggest that apigenin attenuates exacerbation of AD-like symptoms in part through the reduction of serum IgE level and IFN-gamma expression in NC/Nga mice.

In vitro and in vivo anti-inflammatory effects of taheebo, a water extract from the inner bark of Tabebuia avellanedae

AIM OF STUDY

Tabebuia spp. (Bignoniaceae) are native to tropical rain forests throughout Central and South America and have long been used as a folk medicine to treat bacterial infection, blood coagulation, cancer and inflammatory diseases. In this study, we aimed to demonstrate the ethnopharmacological activity of Tabebuia avellanedae in various in vitro and in vivo inflammatory conditions.

MATERIALS AND METHODS

To do this, LPS-stimulated macrophages and arachidonic acid or croton oil-induced mouse ear edema models were employed.

RESULTS

The water extract (taheebo) of Tabebuia avellanedae significantly suppressed the production of prostaglandin (PG) E(2) and nitric oxide (NO), and blocked the mRNA expression of their catalyzing enzymes (cyclooxygenase [COX)-II] and inducible NO synthase [iNOS], respectively), in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The blockade of inflammatory mediators by taheebo seemed to be the result of the interruption of extracellular signal-related kinase (ERK) activation, according to immunoblotting analysis and the NO assay, where LPS strongly induced the phosphorylation (a hallmark of activation) of ERK, and U0126, a selective ERK inhibitor, was found to strongly inhibit PGE(2) production. Similarly, oral administration of taheebo (100mg/kg) for 1 week completely diminished mouse ear edema induced by arachidonic acid, an activator of COX-II, but not croton oil, an activator of lipoxygenase.

CONCLUSIONS

These data suggest that the ethnopharmacological action of taheebo may be due to its negative modulation of macrophage-mediated inflammatory responses by suppressing PGE(2) production. Thus, this water extract may be developed as a new therapeutic remedy for various inflammatory diseases such as arthritis and atherosclerosis.

LEF-1 negatively controls interleukin-4 expression through a proximal promoter regulatory element

Lymphoid enhancer-binding factor 1 (LEF-1) and T cell factor (TCF-1) are downstream effectors of the Wnt signaling pathway and are involved in the regulation of T cell development in the thymus. LEF-1 and TCF-1 are also expressed in mature peripheral primary T cells, but their expression is down-regulated following T cell activation. Although the decisive roles of LEF-1 and TCF-1 in the early stages of T cell development are well documented, the functions of these factors in mature peripheral T cells are largely unknown. Recently, LEF-1 was shown to suppress Th2 cytokines interleukin-4 (IL-4), -5, and -13 expression from the developing Th2 cells that overexpress LEF-1 through retrovirus gene transduction. In this study, we further investigated the expression and functions of LEF-1 and TCF-1 in peripheral CD4+ T cells and revealed that LEF-1 is dominantly expressed in Th1 but not in Th2 cells. We identified a high affinity LEF-1-binding site in the negative regulatory element of the IL-4 promoter. Knockdown LEF-1 expression by LEF-1-specific small interfering RNA resulted in an increase in the IL-4 mRNA expression. This study further confirms a negative regulatory role of LEF-1 in mature peripheral T cells. Furthermore, we found that IL-4 stimulation possesses a negative effect on the expressions of LEF-1 and TCF-1 in primary T cells, suggesting a positive feedback effect of IL-4 on IL4 gene expression.

In vitro immunoregulatory effects of Korean mistletoe lectin on functional activation of monocytic and macrophage-like cells

Korean mistletoe lectin (KML) is one of the major active components in Viscum album var. (coloratum), displaying various biological effects such as anti-tumor and anti-metastatic activities. Even though it has been shown to boost host immune defense mechanisms, the immunomodulatory effects of KML on specific immune responses mediated by macrophages have not been fully elucidated. Therefore, in this study, we aimed to demonstrate KML's regulatory roles on macrophage-mediated immune responses. KML clearly blocked lipopolysaccharide (LPS)-induced events [expression of interleukin (IL)-10, nitric oxide (NO) production and phagocytic uptake], and suppressed the normal expression levels of IL-10 (at 2 ng/ml) and tumor necrosis factor (TNF)-alpha (at 10 ng/ml). In contrast, (1) the expression of cytokine (TNF-alpha) and (2) the generation of reactive oxygen species (ROS) induced by LPS were significantly up-regulated with KML co-treatment. In addition, KML itself increased the mRNA levels of IL-3 and IL-23; phagocytic uptake; the surface levels of co-stimulatory molecules (CD80 and CD86), pattern recognition receptors (PRRs) [such as dectin-1 and toll like receptor (TLR)-2] and adhesion molecules [beta1-integrins (CD29) and CD43]; and CD29-mediated cell adhesion events. Finally, according to co-treatment of D-galactose with KML under LPS-induced NO production conditions, KML inhibition seems to be mediated by binding to proteins with D-galactose. Therefore, these data suggest that KML may participate in regulating various macrophage-mediated innate and adaptive responses via binding to surface protein with D-galactose and that some of these may deserve in KML's therapeutic activities such as anti-tumor and anti-microbial effects.

Immunomodulatory effect of Hibiscus cannabinus extract on macrophage functions

Hibiscus cannabinus L. (Malvaceae) (known as Kenaf) has long been used as a folk medicine in India and Africa for the treatment of blood and throat disorders, bilious conditions, fever and puerperium. In this study, therefore, we aimed either to demonstrate its ethnopharmacological activity by examining its macrophage function-regulating effects or to expand its therapeutic efficacy into other macrophage-mediated diseases. The total crude extract (EtOH extract) of Hibiscus cannabinus fresh leaves, prepared with 80% ethanol, significantly suppressed TNF-alpha production and the mRNA expression of interleukin (IL)-3 and IL-12 in the RAW264.7 cells, stimulated by lipopolysaccharide (LPS, 2.5 microg/ml). The secretion of inflammatory mediators (i.e., nitric oxide [NO], reactive oxygen species [ROS] and prostaglandin E(2) [PGE(2)]) was diminished by the EtOH extract. The extract induced the expression of heme oxygenase-1 (HO-1) mRNA, a potent cytoprotective molecule. The Kenaf extract suppressed both the phagocytic uptake and the expression of costimulatory molecules (CD80 and CD86) of LPS-activated RAW264.7 cells. It is interesting that Kenaf also down-regulated both the functional activation of beta1-integrin (CD29) and the LPS-induced up-regulation of the surface CD29 level. Taken together, these data suggest that Kenaf may be able to modulate macrophage-mediated responses and that some of the activities may contribute to expand its therapeutic usage.

Novel role for mitochondria: protein kinase Ctheta-dependent oxidative signaling organelles in activation-induced T-cell death

Reactive oxygen species (ROS) play a key role in regulation of activation-induced T-cell death (AICD) by induction of CD95L expression. However, the molecular source and the signaling steps necessary for ROS production are largely unknown. Here, we show that the proximal T-cell receptor-signaling machinery, including ZAP70 (zeta chain-associated protein kinase 70), LAT (linker of activated T cells), SLP76 (SH2 domain-containing leukocyte protein of 76 kDa), PLCgamma1 (phospholipase Cgamma1), and PKCtheta (protein kinase Ctheta), are crucial for ROS production. PKCtheta is translocated to the mitochondria. By using cells depleted of mitochondrial DNA, we identified the mitochondria as the source of activation-induced ROS. Inhibition of mitochondrial electron transport complex I assembly by small interfering RNA (siRNA)-mediated knockdown of the chaperone NDUFAF1 resulted in a block of ROS production. Complex I-derived ROS are converted into a hydrogen peroxide signal by the mitochondrial superoxide dismutase. This signal is essential for CD95L expression, as inhibition of complex I assembly by NDUFAF1-specific siRNA prevents AICD. Similar results were obtained when metformin, an antidiabetic drug and mild complex I inhibitor, was used. Thus, we demonstrate for the first time that PKCtheta-dependent ROS generation by mitochondrial complex I is essential for AICD.

Microarray analysis reveals influence of the sesquiterpene lactone parthenolide on gene transcription profiles in human epithelial cells

Sesquiterpene lactones are known for their anti-inflammatory activity which has been proven in various assays on DNA, mRNA and protein level. Here we report on the change in the gene expression profile in TNF-alpha stimulated human 293 cells after treatment with parthenolide using a cDNA microarray analysis. Twenty-one of 7028 genes were found to be up- and 18 down-regulated. They encode for chemoattractants, immune system proteins, glycoproteins, metabolism, serine proteinases, and transcription factors. Confirmatory analyses were carried out using quantitative real-time RT-PCR (TaqMan). Additional studies with selected genes revealed the concentration-dependent influence of parthenolide on the expression of these genes.

Rocaglamide derivatives are immunosuppressive phytochemicals that target NF-AT activity in T cells

Aglaia (family Meliaceae) plants are used in traditional medicine (e.g., in Vietnam) for the treatment of inflammatory skin diseases and allergic inflammatory disorders such as asthma. Inflammatory diseases arise from inappropriate activation of the immune system, leading to abnormal expression of genes encoding inflammatory cytokines and tissue-destructive enzymes. The active compounds isolated from these plants are derivatives of rocaglamide. In this study we show that rocaglamides are potent immunosuppressive phytochemicals that suppress IFN-gamma, TNF-alpha, IL-2, and IL-4 production in peripheral blood T cells at nanomolar concentrations. We demonstrate that rocaglamides inhibit cytokine gene expression at the transcriptional level. At the doses that inhibit cytokine production, they selectively block NF-AT activity without impairing NF-kappaB and AP-1. We also show that inhibition of NF-AT activation by rocaglamide is mediated by strong activation of JNK and p38 kinases. Our study suggests that rocaglamide derivatives may serve as a new source of NF-AT-specific inhibitors for the treatment of certain inflammatory diseases.

Ultraviolet Irradiation Suppresses T Cell Activation via Blocking TCR-Mediated ERK and NF-κB Signaling Pathways

UV irradiation is carcinogenic and immunosuppressive. Previous studies indicate that UV-mediated alteration of APCs and induction of suppressor T cells play a critical role in UV-induced immune suppression. In this study, we show that UV irradiation can directly (independently of APCs and suppressor T cells) inhibit T cell activation by blocking TCR-mediated phosphorylation of ERK and IkappaB via overactivation of the p38 and JNK pathways. These events lead to the down-modulation of c-Jun, c-Fos, Egr-1, and NF-kappaB transcription factors and thereby inhibit production of cytokines, e.g., IL-2, IL-4, IFN-gamma, and TNF-alpha, upon TCR stimulation. We also show that UV irradiation can suppress preactivated T cells, indicating that UV irradiation does not only impair T cell function in response to T cell activation, but can also have systemic effects that influence ongoing immune responses. Thus, our data provide an additional mechanism by which UV irradiation directly suppresses immune responses.

Sesquiterpene lactones inhibit luciferase but not β-galactosidase activity in vitro and ex vivo

Reporter enzymes such as firefly luciferase or beta-galactosidase of Escherichia coli are frequently used to study transcriptional activity of genes and to investigate the effects of novel compounds on gene or transcription factor activity. It is generally assumed that the activity of these enzymes is unaffected by the treatment conditions. Therefore, this factor is not considered when interpreting the data obtained. Biologically active compounds such as sesquiterpene lactones (SLs) have also been tested in reporter gene assays for their influence on gene expression. Here we show in in vitro and ex vivo experiments that SLs inhibit firefly luciferase activity probably by direct targeting of the enzyme while beta-galactosidase remains almost completely unaffected. The loss of luciferase activity after SL treatment could be an effect of their sulfhydryl-modifying potency and the subsequent alteration of the enzyme's tertiary structure. These results demonstrate that the effect of the test substance on the reporter enzyme used should be taken into consideration when the transcriptional effect of novel compounds is investigated.

Costunolide inhibits interleukin-1β expression by down-regulation of AP-1 and MAPK activity in LPS-stimulated RAW 264.7 cells

Costunolide, a sesquiterpene lactone isolated from the root of Saussurea lappa Clarke, is known to have a variety of biological activities, including anti-carcinogenic and anti-fungal activities. Here, we demonstrated the inhibitory effect of costunolide on the protein and mRNA expression of interleukin-1beta (IL-1beta) in LPS-stimulated RAW 264.7 cells. We also showed that costunolide suppressed the transcriptional activity of the IL-1beta promoter. Moreover, costunolide inhibited the activity of AP-1 transcription factor, and the phosphorylation of MAPKs, including SAPK/JNK and p38 MAP kinase. The inhibitory effect of costunolide on AP-1 activity was also confirmed by an electrophoretic mobility shift assay. Additionally, specific inhibitors of SAPK/JNK and p38 MAP kinase, SP600125 and SB203580, also suppressed LPS-induced increase in IL-1beta gene expression and AP-1 DNA binding. Taken together, these results demonstrate that costunolide inhibits IL-1beta gene expression by blocking the activation of MAPKs and DNA binding of AP-1 in LPS-stimulated RAW 264.7 cells.

Regulation of IL4 gene expression by T cells and therapeutic perspectives

Interleukin-4 (IL-4) is crucial for the differentiation of naive T helper (T(H)) cells into the T(H)2 effector cells that promote humoral (antibody) immunity and provide protection against intestinal helminths. IL-4 also has a central role in the pathogenesis of allergic inflammation. Many transcription factors are involved in the regulation of expression of the gene encoding IL-4. Initiation of transcription of the gene encoding IL-4 in naive T(H) cells is regulated by the T(H)2-specific transcription factor GATA3, whereas acute expression of the gene encoding IL-4 in T(H)2 cells is mediated by inducible, ubiquitous transcription factors after antigen encounter. This review focuses on acute activation of the gene encoding IL-4 in T cells and discusses therapeutic perspectives at the transcriptional level.

Effect of sesquiterpene lactones on the expression of the activation marker CD69 and of IL-2 in T-lymphocytes in whole blood

We used flow cytometry to investigate the inhibitory effect of sesquiterpene lactones (SLs) on T-cell activation measured by the expression of its early marker CD69, and on interleukin (IL)-2, a mediator of activation, in whole blood. SLs are biologically active compounds found especially in plants from the Asteraceae family. Overnight treatment of blood with these substances led to the inhibition of CD69 and IL-2 expression. Interestingly, bifunctional SLs showed a weaker activity than monofunctional substances, which is in contradiction with the data obtained so far, using other biological test systems. Additionally, SLs did not completely inhibit CD69 or IL-2 expression. We also determined their toxicity and observed only a low effect. Up to now, studies on cytotoxicity have only been performed using cultured cell lines. From these results it may be supposed that these natural compounds preferentially show toxic effects towards transformed cell lines. Altogether, the results demonstrated that SLs effectively inhibit the activation of the T-lymphocyte response in whole blood and proved the utility of a whole blood system in studying their biological effects.