Apigenin protects ovalbumin-induced asthma through the regulation of GATA-3 gene

Apigenin: A Bioflavonoid with a Promising Role in Disease Prevention and Treatment

Apigenin is a powerful flavone compound found in numerous fruits and vegetables, and it offers numerous health-promoting benefits. Many studies have evidenced that this compound has a potential role as an anti-inflammatory and antioxidant compound, making it a promising candidate for reducing the risk of pathogenesis. It has also been found to positively affect various systems in the body, such as the respiratory, digestive, immune, and reproductive systems. Apigenin is effective in treating liver, lung, heart, kidney, neurological diseases, diabetes, and maintaining good oral and skin health. Multiple studies have reported that this compound is capable of suppressing various types of cancer through the induction of apoptosis and cell-cycle arrest, suppressing cell migration and invasion, reduction of inflammation, and inhibiting angiogenesis. When used in combination with other drugs, apigenin increases their efficacy, reduces the risk of side effects, and improves the response to chemotherapy. This review broadly analyzes apigenin's potential in disease management by modulating various biological activities. In addition, this review also described apigenin's interaction with other compounds or drugs and the potential role of nanoformulation in different pathogeneses. Further extensive research is needed to explore the mechanism of action, safety, and efficacy of this compound in disease prevention and treatment.

Unveiling the Immunomodulatory Potential of Phenolic Compounds in Food Allergies

Food allergies are becoming ever more prevalent around the world. This pathology is characterized by the breakdown of oral tolerance to ingested food allergens, resulting in allergic reactions in subsequent exposures. Due to the possible severity of the symptoms associated with this pathology, new approaches to prevent it and reduce associated symptoms are of utmost importance. In this framework, dietary phenolic compounds appear as a tool with a not fully explored potential. Some phenolic compounds have been pointed to with the ability to modulate food allergies and possibly reduce their symptoms. These compounds can modulate food allergies through many different mechanisms, such as altering the bioaccessibility and bioavailability of potentially immunogenic peptides, by modulating the human immune system and by modulating the composition of the human microbiome that resides in the oral cavity and the gastrointestinal tract. This review deepens the state-of-the-art of the modulation of these mechanisms by phenolic compounds. While this review shows clear evidence that dietary supplementation with foods rich in phenolic compounds might constitute a new approach to the management of food allergies, it also highlights the need for further research to delve into the mechanisms of action of these compounds and decipher systematic structure/activity relationships.

Transcriptomics reveals apigenin alleviates airway inflammation and epithelial cell apoptosis in allergic asthma via MAPK pathway

Persistent chronic inflammation of the lungs and airway remodeling are important pathological features that cannot be ignored in patients with chronic asthma. Apigenin (API) is a natural small molecule compound with good anti-inflammatory and antioxidant activity that has been widely reported in recent years, but its role in chronic asthma is not well defined. Our study began with oral gavage intervention using API (10, 20 mg/kg) or dexamethasone (DEX, 2 mg/kg) in a BALB/c mouse model of ovalbumin (OVA) sensitization. Different doses of API intervention effectively reduced airway resistance in the administered group. Additionally, inflammation was downregulated, mucus secretion was reduced, and airway remodeling was inhibited in the API intervention group compared with the model group. Asthma-related inflammatory cytokines, such as IgE, IL-4, IL-5, IL-13, and IL-17, were downregulated in alveolar lavage fluid. Moreover, the apoptosis level of the administered group was found to be lower than that of the model group in the Tunel staining experiment. By analyzing transcriptome sequencing results, we found that API may exert anti-inflammatory and anti-apoptotic effects by inhibiting the MAPK pathway. Our subsequent results supported this conclusion, showing that the phosphorylation levels of ERKs, JNKs, and p38 MAPKs were inhibited in the administered group relative to the model group. Downstream expression of the apoptosis-related protein B-cell lymphoma-2 (Bcl-2) was upregulated, and the expression of Bcl-2-associated × protein (Bax) and cleaved caspase-3 was downregulated. To further investigate the specific mechanism by which API acted, we established an in vitro model with house dust mite (HDM) stimulation, using API (10, 20 μM) for administration intervention. The results showed that API was able to improve cell viability, inhibit ROS production, and reverse HDM-induced decreases in mitochondrial membrane potential (MMP) and apoptosis in airway epithelial cells via the MAPK pathway.

The effect of apigenin, an aryl hydrocarbon receptor antagonist, in Phthalate-Exacerbated eosinophilic asthma model

Endocrine disrupting chemicals have been known to contribute to the aggravation of inflammatory diseases including asthma. We aimed to investigate the effects of mono-n-butyl phthalate (MnBP) which is one of the representing phthalates, and its antagonist in an eosinophilic asthma mouse model. BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) with alum and followed by three nebulized OVA challenges. MnBP was administered through drinking water administration throughout the study period, and its antagonist, apigenin, was orally treated for 14 days before OVA challenges. Mice were assessed for airway hyperresponsiveness (AHR), differential cell count and type 2 cytokines in bronchoalveolar lavage fluid were measured in vivo. The expression of the aryl hydrocarbon receptor was markedly increased when MnBP was administered. MnBP treatment increased AHR, airway inflammatory cells (including eosinophils), and type 2 cytokines following OVA challenge compared to vehicle-treated mice. However, apigenin treatment reduced all asthma features, such as AHR, airway inflammation, type 2 cytokines, and the expression of the aryl hydrocarbon receptor in MnBP-augmented eosinophilic asthma. Our study suggests that MnBP exposure may increase the risk of eosinophilic inflammation, and apigenin treatment may be a potential therapy for asthma exacerbated by endocrine-disrupting chemicals.

Therapeutic Potential of Controlled Delivery Systems in Asthma: Preclinical Development of Flavonoid-Based Treatments

Asthma is a chronic disease with increasing prevalence and incidence, manifested by allergic inflammatory reactions, and is life-threatening for patients with severe disease. Repetitive challenges with the allergens and limitation of treatment efficacy greatly dampens successful management of asthma. The adverse events related to several drugs currently used, such as corticosteroids and β-agonists, and the low rigorous adherence to preconized protocols likely compromises a more assertive therapy. Flavonoids represent a class of natural compounds with extraordinary antioxidant and anti-inflammatory properties, with their potential benefits already demonstrated for several diseases, including asthma. Advanced technology has been used in the pharmaceutical field to improve the efficacy and safety of drugs. Notably, there is also an increasing interest for the application of these techniques using natural products as active molecules. Flavones, flavonols, flavanones, and chalcones are examples of flavonoid compounds that were tested in controlled delivery systems for asthma treatment, and which achieved better treatment results in comparison to their free forms. This review aims to provide a comprehensive understanding of the development of novel controlled delivery systems to enhance the therapeutic potential of flavonoids as active molecules for asthma treatment.

Molecular and Immunomodulatory Actions of New Antiasthmatic Agents: Exploring the Diversity of Biologics in Th2 Endotype Asthma

Asthma is a major respiratory disorder characterised by chronic inflammation and airway remodelling. It affects about 1-8% of the global population and is responsible for over 461,000 deaths annually. Until recently, the pharmacotherapy of severe asthma involved high doses of inhaled corticosteroids in combination with β-agonist for prolonged action, including theophylline, leukotriene antagonist or anticholinergic yielding limited benefit. Although the use of newer agents to target Th2 asthma endotypes has improved therapeutic outcomes in severe asthmatic conditions, there seems to be a paucity of understanding the diverse mechanisms through which these classes of drugs act. This article delineates the molecular and immunomodulatory mechanisms of action of new antiasthmatic agents currently being trialled in preclinical and clinical studies to remit asthmatic conditions. The ultimate goal in developing antiasthmatic agents is based on two types of approaches: either anti-inflammatory or bronchodilators. Biologic and most small molecules have been shown to modulate specific asthma endotypes, targeting thymic stromal lymphopoietin, tryptase, spleen tyrosine kinase (Syk), Janus kinase, PD-L1/PD-L2, GATA-3, and CD38 for the treatment and management of Th2 endotype asthma.

The Immunomodulatory Effects of Honey and Associated Flavonoids in Cancer

Honey has exerted a high impact in the field of alternative medicine over many centuries. In addition to its wound healing, anti-microbial and antioxidant properties, several lines of evidence have highlighted the efficiency of honey and associated bioactive constituents as anti-tumor agents against a range of cancer types. Mechanistically, honey was shown to inhibit cancer cell growth through its pro-apoptotic, anti-proliferative and anti-metastatic effects. However, the potential of honey to regulate anti-tumor immune responses is relatively unexplored. A small number of in vitro and in vivo studies have demonstrated the ability of honey to modulate the immune system by inducing immunostimulatory as well as anti-inflammatory effects. In the present review, we summarize the findings from different studies that aimed to investigate the immunomodulatory properties of honey and its flavonoid components in relation to cancer. While these studies provide promising data, additional research is needed to further elucidate the immunomodulatory properties of honey, and to enable its utilization as an adjuvant therapy in cancer.

Evaluation of the effect of hydroalcoholic and flavonoid-enriched extracts of Dracocephalum kotschyi on indomethacin-induced gastric ulcer in rats

Background and purpose:

Dracocephalum kotschyi (Zaringiah) is a fragrant wild medicinal plant found in Iran. Traditionally, it is used for the treatment of rheumatism, asthma, and gastrointestinal ailments. So far no investigation has been done on the beneficial or side effects of D. kotschyi on peptic ulcer. Therefore, this research was performed to find out whether D. kotschyi extract would induce peptic ulcer or could alleviate existing peptic ulcer.

Experimental approach:

Effect of hydroalcoholic (DKHE) and flavonoid extracts (DKFE) of D. kotschyi were determined in normal or indomethacin-induced gastric ulcer rats (n = 6) and compared with the vehicle and ranitidine treated controls. All the treatments were carried out orally and 24 h later the stomach mucus was visually examined for peptic ulcers. A section of the stomach was taken for microscopic histopathological examinations while another section of the stomach was used for measurement of myeloperoxidase (MPO) and malondialdehyde (MDA) activities.

Findings/Results:

Oral administration of the DKHE and DKFE alone, did not cause any sign of gastric ulcer induction. The D. kotschyi extracts not only didn’t aggravate the induced ulcer but also significantly prevented the severity of gastric ulcer induction by indomethacin. In addition, DKHE and DKFE inhibited MPO (up to 58.2%) and MDA (up to 44.2%) activities indicating their anti-inflammatory and antioxidant potential action on the stomach-induced ulcer.

Conclusion and implication:

Usage of D. kotschyi extracts is not associated with gastric ulcer induction and its co-administration with NSAIDs would be beneficial for controlling both the inflammation and preventing gastric ulcer in diseases such as rheumatism.

Attenuating Effect of Peruvian Cocoa Populations on the Acute Asthmatic Response in Brown Norway Rats

Cocoa contains bioactive components, which vary according to genetic and environmental factors. The present study aimed to ascertain the anti-allergic properties of native Peruvian cocoa populations ("Blanco de Piura" or BPC, "Amazonas Peru" or APC, "Criollo de Montaña" or CMC, "Chuncho" or CCC, and an ordinary cocoa or OC). To do so, after an initial in vitro approach, an in vivo study focused on the induction of an anaphylactic response associated with allergic asthma in Brown Norway rats was carried out. Based on their polyphenol content, antioxidant activity and in vitro effects, the APC and CMC were selected to be included in the in vivo study. Cocoa diets were tested in a model of allergic asthma in which anaphylactic response was assessed by changes in body temperature, motor activity and body weight. The concentration of specific immunoglobulin E (IgE), mast cell protease and leukotrienes was also quantified in serum and/or bronchoalveolar lavage fluid. CMC and OC populations exhibited a protective effect on the allergic asthma rat model as evidenced by means of a partial protection against anaphylactic response and, above all, in the synthesis of IgE and the release of mast cell protease.

Apigenin Attenuates Allergic Responses of Ovalbumin-Induced Allergic Rhinitis Through Modulation of Th1/Th2 Responses in Experimental Mice

Background

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated immune-inflammatory response mainly affecting nasal mucosa. Apigenin, a flavonoid, has been documented to possess promising anti-allergic potential.

Aim

To determine the potential mechanism of action of apigenin against ovalbumin (OVA)-induced AR by assessing various behavioral, biochemical, molecular, and ultrastructural modifications.

Materials and Methods

Allergic rhinitis was induced in BALB/c mice (18-22 grams) by sensitizing it with OVA (5%, 500 μL, intraperitoneal [IP] on each consecutive day, for 13 days) followed by intranasal challenge with OVA (5%, 5 μL per nostril on day 21). Animals were treated with either vehicle (distilled water, 10 mg/kg, IP) or apigenin (5, 10, and 20 mg/kg, IP).

Results

Intranasal challenge of OVA resulted in significant induction (P < .05) of AR reflected by an increase in nasal symptoms (sneezing, rubbing, and discharge), which were ameliorated significantly (P < .05) by apigenin (10 and 20 mg/kg) treatment. It also significantly inhibited (P < .05) OVA-induced elevated serum histamine, OVA-specific IgE, total IgE, and IgG1 and β-hexosaminidase levels. Ovalbumin-induced increased levels of interleukin (IL)-4, IL-5, IL-13, and interferon (IFN)-γ in nasal lavage fluid were significantly decreased (P < .05) by apigenin. Ovalbumin-induced alterations in splenic GATA binding protein 3 (ie, erythroid transcription factor) (GATA3), T-box protein expressed in T cells (T-bet), signal transducer and activator of transcription-6 (STAT6), suppressor of cytokine signaling 1 (SOCS1), nuclear factor-kappa B (NF-κB), and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha messenger RNA, as well as protein expressions were significantly inhibited (P < .05) by apigenin. It also significantly ameliorated (P < .05) nasal and spleen histopathologic and ultrastructure aberration induced by OVA.

Conclusion

Apigenin regulates Th1/Th2 balance via suppression in expressions of Th2 response (IgE, histamine, ILs, GATA3, STAT6, SOCS1, and NF-κB) and activation of Th1 response (IFN-γ and T-bet) to exert its anti-allergic potential in a murine model of OVA-induced AR.

Bronchodilator effect of apigenin and luteolin, two components of Dracocephalum kotschyi on isolated rabbit trachea

Introduction: Dracocephalum kotschyi is a native Iranian plant with antispasmodic activities on smooth muscles such as ileum and uterus. However, so far antispasmodic effect of D. kotschyi on tracheal smooth muscle has not been reported. Therefore, the objective of this research was to investigate antispasmodic activity of D. kotschyi extract and two of its components luteolin and apigenin on rabbit tracheal contraction in vitro. Methods: Rabbits were euthanized by carbon dioxide and the trachea was dissected and immersed in a Tyrode’s solution. Tracheal rings were prepared and mounted vertically in an organ bath at 37°C and gassed continuously with O2. The tracheal ring preparations were contracted with acetylcholine (ACh) and KCl. The isotonic tension was recorded before and after addition of aminophylline, apigenin, luteolin or flavonoids rich extract of D. kotschyi. Flavonoids rich extract were prepared from D. kotschyi using solvent-solvent fractionation technique. Results: Standard drug aminophylline, prevented tracheal ring preparation contracted with ACh. Cumulative addition of aminophylline also attenuated tonic contraction induced by KCl on tracheal smooth muscle. D. kotschyi extract at concentration ranges of 32-512 μg/mL in a concentration dependent manner inhibited KCl and ACh induced tracheal contraction. Apigenin and luteolin (range 16–512 μg/mL) relaxed KCl and ACh-induced contraction of tracheal smooth muscle in vitro in a concentration-dependent manner. Conclusion: This study demonstrated that D. kotschyi extract is a relaxant of tracheal smooth muscle. The relaxant effect of D. kotschyi extract could be due to its flavonoids component such as apigenin and luteolin.

Betulin protects mice from bacterial pneumonia and acute lung injury

Betulin, a naturally occurring triterpene, has shown anti-HIV activity, but details on the anti-inflammatory activity are scanty. In this study, we sought to investigate the effect of Betulin on LPS-induced activation of cell lines with relevance for lung inflammation in vitro and on lung inflammation elicited by either LPS or viable Escherichia coli (E. coli) in vivo. In vitro, Betulin inhibited LPS-induced tumor necrosis factor α (TNF-α) and (interleukin) IL-6 levels and up-regulated the level of IL-10. Also Betulin suppressed the phosphorylation of nuclear factor-κB (NF-κB) p65 protein in LPS-stimulated RAW 264.7 cells. In vivo, Betulin alleviated LPS-induced acute lung injury. Treatment with Betulin diminished pro-inflammatory cytokines, myeloperoxidase activity and bacterial loads in lung tissue during gram-negative pneumonia. Our findings demonstrated that Betulin inhibits pro-inflammatory responses induced by the gram-negative stimuli LPS and E. coli, suggesting that Betulin may represent a novel strategy for the treatment of lung inflammation.

Regulatory effect of microRNA-135a on the Th1/Th2 imbalance in a murine model of allergic rhinitis

Allergic rhinitis (AR) is primarily caused by a T helper cell (Th)1/Th2 imbalance. In a murine AR model of a previous study, the serum ovalbumin (OVA)-sIgE concentration was high, whereas microRNA (miR)-135a was lowly expressed in the nasal mucosa. The abnormal expression pattern of miR-135a coincided with highly expressed endogenous factors, including GATA binding protein (GATA)-3 and interleukin (IL)-4, and lowly expressed factors, including T-box expressed in T cells (T-bet) and interferon (IFN)-γ. We hypothesized that miR-135a may play an important role in immune regulation in AR mice. In the present study, AR was induced by OVA in the mice. Two groups of the AR mice were treated with a miR-135a mimic and a mimic control, respectively. The serum and nasal mucosa were collected for analysis. Following miR-135a application, the serum OVA-sIgE concentration was significantly reduced. In the nasal mucosa, the expression levels of miR-135a were higher, the mRNA and protein expression levels of GATA-3 and IL-4 were lower, and the expression levels of T-bet and IFN-γ were higher. The miR-135a corrected the Th1/Th2 imbalance in the AR mice. Findings of this study may provide a basis for novel genetic treatments in addressing allergic diseases.

Cyanidin-3-glucoside suppresses Th2 cytokines and GATA-3 transcription factor in EL-4 T cells

Allergic disease is dominated by Th2 immune responses. Interleukin (IL)-4 and IL-13, representative Th2 cytokines, play pivotal roles in the pathogenic activation of the Th2 immune response. In this study, we found that cyanidin-3-glucoside chloride (C3G), an anthocyanin suppressed IL-4 and IL-13 produced in activated EL-4 T cells but not Th1 cytokines including IL-2, interferon-γ, or IL-12. IL-4 and IL-13 mRNA levels and luciferase activation in cells transiently transfected with IL-4 and IL-13 promoter reporter plasmids were significantly inhibited by C3G, suggesting that suppression might be, at least in part, regulated at the transcriptional level. Data from western blot and reverse transcription-polymerase chain reaction analyses of transcription factors involved in cytokine expression suggested that expression of GATA-3, but not T-bet, was downregulated in the nucleus by C3G. Taken together, our data indicate that C3G may has potential as an anti-allergic agent suppressing Th2 activation by downregulating Th2 cytokines and the GATA3 transcription factor in allergies.

Laser-engineered dissolving microneedle arrays for protein delivery: potential for enhanced intradermal vaccination

OBJECTIVES

We aimed to highlight the utility of novel dissolving microneedle (MN)-based delivery systems for enhanced transdermal protein delivery. Vaccination remains the most accepted and effective approach in offering protection from infectious diseases. In recent years, much interest has focused on the possibility of using minimally invasive MN technologies to replace conventional hypodermic vaccine injections.

METHODS

The focus of this study was exploitation of dissolving MN array devices fabricated from 20% w/w poly(methyl vinyl ether/maleic acid) using a micromoulding technique, for the facilitated delivery of a model antigen, ovalbumin (OVA).

KEY FINDINGS

A series of in-vitro and in-vivo experiments were designed to demonstrate that MN arrays loaded with OVA penetrated the stratum corneum and delivered their payload systemically. The latter was evidenced by the activation of both humoral and cellular inflammatory responses in mice, indicated by the production of immunoglobulins (IgG, IgG1, IgG2a) and inflammatory cytokines, specifically interferon-gamma and interleukin-4. Importantly, the structural integrity of the OVA following incorporation into the MN arrays was maintained.

CONCLUSION

While enhanced manufacturing strategies are required to improve delivery efficiency and reduce waste, dissolving MN are a promising candidate for 'reduced-risk' vaccination and protein delivery strategies.

Expression of neuronal protein Kidins220/ARMS in the spleen and peripheral blood of mice following airway allergen challenge

Nerve growth factor (NGF), combined with the high-affinity tyrosine kinase receptor A (TrkA), has been reported to be involved in the pathogenesis of asthma. Ankyrin-rich membrane spanning/transmembrane substrate of protein kinase D (ARMS/Kidins220), a TrkA‑binding protein, modulates the NGF signaling pathway. The aim of the present study was to investigate the expression of Kidins220/ARMS and the effect NGF has on the protein in the spleen and peripheral blood, following airway allergen challenge in mice. BALB/c mice were sensitized and challenged with ovalbumin. The effects of NGF on Kidins220/ARMS in the spleen and peripheral blood of mice were assessed by administering anti-NGF antibody. Expression of ARMS, interleukin (IL)-1β and IL-4 in the spleen and peripheral blood was observed by reverse transcription-polymerase chain reaction, western blot analysis and immunohistochemistry. Pathological changes in the bronchi and lung tissues were examined by hematoxylin and eosin staining. Results showed that Kidins220/ARMS, IL-1β and IL-4 were overexpressed in the spleen and peripheral blood following allergen challenge, compared with the control mice. Moreover, following treatment with anti-NGF, the levels of Kidins220/ARMS, IL-1β and IL-4 in the mice were downregulated. Therefore, the results of the present study showed that Kidins220/ARMS is expressed in the spleen and peripheral blood of normal BALB/c mice and may participate in the immuno-inflammation of asthma through the NGF-mediated signaling pathway.

Apigenin protects ovalbumin-induced asthma through the regulation of Th17 cells

The aim of the study was to investigate the anti-asthmatic effects of apigenin and the possible mechanisms. Asthma model was established by ovalbumin-induced asthma. A total of 50 mice were randomly assigned to six experimental groups: control, model, dexamethasone (2 mg/kg) and apigenin (5 mg/kg, 10 mg/kg). Airway resistance (Raw) was measured, histological studies were evaluated by hematoxylin and eosin (HE) staining, OVA-specific serum and BALF IgE levels and Th17 cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA), Th17 cells were evaluated by flow cytometry (FCM), and protein level of RORγt was measured by western blotting. Our study demonstrated that apigenin inhibited OVA-induced increases in Raw and eosinophil count; interleukin (IL)-6, TNF- and IL-17A levels were recovered. Histological studies demonstrated that apigenin substantially inhibited OVA-induced eosinophilia in lung tissue and airway tissue. Flow cytometry studies demonstrated that apigenin substantially inhibited Th17 cells. Western blotting studies demonstrated that apigenin substantially inhibited RORγt protein level. These findings suggest that apigenin may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

Flavonoids and asthma

Asthma is a chronic disease, characterized by airway inflammation, airflow limitation, hyper-reactivity and airway remodeling. It is believed that asthma is caused by the interaction between genetic and environmental factors. The prevalence of allergic diseases, including asthma, has increased worldwide during the past two decades. Although the precise reasons that have caused this increase remain unknown, dietary change is thought to be one of the environmental factors. Flavonoids, which are polyphenolic plant secondary metabolites ubiquitously present in vegetables, fruits and beverages, possess antioxidant and anti-allergic traits, as well as immune-modulating activities. Flavonoids are powerful antioxidants and anti-allergic nutrients that inhibit the release of chemical mediators, synthesis of Th2 type cytokines, such as interleukin (IL)-4 and IL-13, and CD40 ligand expression by high-affinity immunoglobulin E (IgE) receptor-expressing cells, such as mast cells and basophils. They also inhibit IL-4-induced signal transduction and affect the differentiation of naïve CD4+ T cells into effector T-cells through their inhibitory effect on the activation of the aryl hydrocarbon receptor. Various studies of flavonoids in asthmatic animal models have demonstrated their beneficial effects. The results of several epidemiological studies suggest that an increase in flavonoid intake is beneficial for asthma. Moreover, clinical trials of flavonoids have shown their ameliorative effects on symptoms related to asthma. However, these human studies are currently limited; further validation is required to clarify whether an appropriate intake of flavonoids may constitute dietary treatment and for part of a preventive strategy for asthma.

Ocimum gratissimum Linn. and rosmarinic acid, attenuate eosinophilic airway inflammation in an experimental model of respiratory allergy to Blomia tropicalis

Allergic asthma has emerged as an important public health problem of urban populations in developed countries. Very often herbal medicine is used to treat this widespread disease, due to the lack of efficacy and the important side effects related to the classical drugs in use. Along this line, Ocimum gratissimum (Og) is a plant widely used in Brazilian folk medicine to treat inflammatory disorders, such as asthma. In the present study we evaluated the immunomodulatory effects of Og and rosmarinic acid (RA, a polyphenolic compound) in a murine model of respiratory allergy induced by the Blomia tropicalis (Bt) mite. The respiratory allergy was induced in A/J mice by administration of Bt extract and the treatment was done using 25, 50 or 100mg/kg of an Og methanolic extract or using 2, 20 or 200mg/kg of RA. We then evaluated the changes induced by these drugs on immunological parameters related to the allergic process, which are up-regulated in this allergic model. The treatment of animals with 100mg/Kg Og and 200mg/Kg RA led to a significant reduction in the numbers of leukocytes/eosinophils in bronchoalveolar lavage (BAL); eosinophil peroxidase activity in BAL; presence of mucus in respiratory tract, histopathological changes in the lung, and IL-4 in BAL. These results suggest that the methanolic extract of Og and the polyphenol RA have therapeutic potential in this murine model of respiratory allergy to a clinically relevant human sensitizer allergen.

Different effects of farrerol on an OVA-induced allergic asthma and LPS-induced acute lung injury

Background

Farrerol, isolated from rhododendron, has been shown to have the anti-bacterial activity, but no details on the anti-inflammatory activity. We further evaluated the effects of this compound in two experimental models of lung diseases.

Methodology/Principal Findings

For the asthma model, female BALB/c mice were challenged with ovalbumin (OVA), and then treated daily with farrerol (20 and 40 mg/kg, ip) as a therapeutic treatment from day 22 to day 26 post immunization. To induce acute lung injury, female BALB/c mice were injected intranasally with LPS and treated with farrerol (20 and 40 mg/kg, i.p.) 1 h prior to LPS stimulation. Inflammation in the two different models was determined using ELISA, histology, real-time PCR and western blot. Farrerol significantly regulated the phenotype challenged by OVA, like cell number, Th1 and Th2 cytokines levels in the BALF, the OVA-specific IgE level in the serum, goblet cell hyperplasia in the airway, airway hyperresponsiveness to inhaled methacholine and mRNA expression of chemokines and their receptors. Furthermore, farrerol markedly attenuated the activation of phosphorylation of Akt and nuclear factor-κB (NF-κB) subunit p65 both in vivo and in vitro. However, farrerol has no effect on the acute lung injury model.

Conclusion/Significance

Our finding demonstrates that the distinct anti-inflammatory effect of farrerol in the treatment of asthma acts by inhibiting the PI3K and NF-κB pathway.

An essential regulatory role of downstream of kinase-1 in the ovalbumin-induced murine model of asthma

The downstream of kinase (DOK)-1 is involved in the protein tyrosine kinase (PTK) pathway in mast cells, but the role of DOK-1 in the pathogenesis of asthma has not been defined. In this study, we have demonstrated a novel regulatory role of DOK-1 in airway inflammation and physiologic responses in a murine model of asthma using lentiviral vector containing DOK-1 cDNA or DOK-1-specific ShRNA. The OVA-induced inflammatory cells, airway hyperresponsiveness, Th2 cytokine expression, and mucus response were significantly reduced in DOK-1 overexpressing mice compared to OVA-challenged control mice. The transgenic introduction of DOK-1 significantly stimulated the activation and expression of STAT-4 and T-bet, while impressively inhibiting the activation and expression of STAT-6 and GATA-3 in airway epithelial cells. On the other hand, DOK-1 knockdown mice enhanced STAT-6 expression and its nuclear translocation compared to OVA-challenged control mice. When viewed in combination, our studies demonstrate DOK-1 regulates allergen-induced Th2 immune responses by selective stimulation and inhibition of STAT-4 and STAT-6 signaling pathways, respectively. These studies provide a novel insight on the regulatory role of DOK-1 in allergen-induced Th2 inflammation and airway responses, which has therapeutic potential for asthma and other allergic diseases.

Anti-asthmatic potential of chrysin on ovalbumin-induced bronchoalveolar hyperresponsiveness in rats

CONTEXT

Chrysin, a flavonoid obtained from various natural sources, has been reported to act as an anti-inflammatory and antioxidant agent. However, its anti-allergic action is not fully understood.

OBJECTIVE

In this study, we investigated the in vivo anti-asthmatic activity of chrysin.

MATERIALS AND METHODS

The effects of chrysin were evaluated using ovalbumin (OVA) (two subcutaneous 1 mL injections of 20 μg) to induce bronchoalveolar hyperresponsiveness in rats. Chrysin, when administered at 3, 10, and 30 mg/kg, p.o., respectively, before OVA challenge, reduced inflammatory cell (total and differential cell count) infiltration into the lungs measured from bronchoalveolar lavage fluid as supported by lung histology.

RESULTS

The total lung injury score was reduced in a dose-dependent manner, evaluated in six different categories (infiltration of leucocytes, type of inflammatory exudates, status of bronchi, perivascular status of lung blood vessels, integrity of alveoli and activation of alveolar macrophages). Various cellular injury parameters such as alkaline phosphatase, lactate dehydrogenase, and total protein were estimated and found to be reduced by chrysin pretreatment. Further, chrysin was found to reduce nitrite concentration (NO) and lipid peroxidation, suggesting its antioxidant activity.

DISCUSSION AND CONCLUSION

Chrysin showed anti-asthmatic potential, probably due to the alteration of Th1/Th2 polarization via the suppression of inducible nitric oxide synthase, nuclear factor-κB, and activation protein.

Clonorchis sinensis-derived total protein attenuates airway inflammation in murine asthma model by inducing regulatory T cells and modulating dendritic cell functions

Asthma is characterized by Th2-mediated inflammation, resulting in airway hyperresponsiveness (AHR) through airway remodeling. Recent epidemiological and experimental reports have suggested an inverse relationship between the development of allergy and helminth infections. Infection by Clonorchis sinensis, a liver fluke that resides in the bile duct of humans, is endemic predominantly in Asia including Korea and China. Using a murine model for asthma, we investigated the effects of C. sinensis-derived total protein (Cs-TP) on allergen-induced airway inflammation and the mechanism underlying the protective effects of Cs-TP administration on asthma. Treatment with Cs-TP attenuated OVA-induced airway inflammation and methacholine-induced AHR, as well as eosinophilia development, lymphocyte infiltration into the lung, and goblet cell metaplasia. This protective effect of Cs-TP is associated with markedly reduced OVA-specific IgE and Th1/Th2 cytokine production. Moreover, Cs-TP increased the number of CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells as well as their suppressive activity. In fact, proliferation of OVA-restimulated splenocytes was suppressed significantly. Cs-TP also inhibited the expression of such co-stimulatory molecules as CD80, CD86, and CD40 in LPS- or OVA-stimulated dendritic cells (DCs), suggesting that Cs-TP could interfere with the capacity of airway DCs to prime naïve T cells. These data demonstrate the capacity of C. sinensis to ameliorate allergic asthma and broaden our understanding of the paradoxical relationship between the allergic immune response and helminth infection.

NGF/TrkA-mediated Kidins220/ARMS signaling activated in the allergic airway challenge in mice

BACKGROUND

Nerve growth factor (NGF), combined with its high-affinity receptor tyrosine kinase receptor A (TrkA), has been reported to be involved in the pathogenesis of asthma.

OBJECTIVE

To investigate whether the downstream protein ankyrin-rich membrane spanning (ARMS), a novel transmembrane substrate of protein kinase D (Kidins220), is activated in the pathogenesis of asthma.

METHODS

The asthmatic model was established by the inhalation of ovalbumin in BALB/c mice. The effects of NGF and TrkA on Kidins220/ARMS in an allergic airway challenge were assessed by administering anti-NGF or anti-TrkA antibody to the mice. Pathologic changes in the bronchi and lung tissues were examined by means of hematoxylin and eosin staining; the inflammatory cells in the bronchoalveolar lavage fluid (BALF) were counted; and co-expression of ARMS and TrkA in BALF cells was observed by means of immunofluorescence. In addition, Kidins220/ARMS, CrkL, NGF, TrkA protein, and Kidins220 messenger RNA levels were determined using Western blot or quantitative reverse transcription-polymerase chain reaction.

RESULTS

Using fluorescence microscopy, we found that Kidins220 and TrkA were co-expressed on the membranes of the BALF cells of asthmatic mice. Compared with expression in control animals, Kidins220/ARMS, CrkL, NGF, and TrkA were overexpressed in the lungs after allergen challenge. Moreover, after the mice were treated with anti-NGF or anti-TrkA, the Kidins220/ARMS levels and allergen-induced airway inflammation decreased.

CONCLUSIONS

These results suggest that Kidins220/ARMS partly participates in the pathogenesis of asthma through the NGF-TrkA signaling pathway, possibly representing a new mechanism in asthma.

The activity of medicinal plants and secondary metabolites on eosinophilic inflammation

Eosinophils are leukocytes that are present in several body compartments and in the blood at relatively low numbers under normal conditions. However, an increase in the number of eosinophils, in the blood or in the tissues, is observed in allergic or parasitic disorders. Although some progress has been made in understanding the development of eosinophil-mediated inflammation in allergic and parasitic diseases, the discovery of new compounds to control eosinophilia has lagged behind other advances. Plant-derived secondary metabolites are the basis for many drugs currently used to treat pathologic conditions, including eosinophilic diseases. Several studies, including our own, have demonstrated that plant extracts and secondary metabolites can reduce eosinophilia and eosinophil recruitment in different experimental animal models. In this review, we summarize these studies and describe the anti-eosinophilic activity of various plant extracts, such as Ginkgo biloba, Allium cepa, and Lafoensia pacari, as well as those of secondary metabolites (compounds isolated from plant extracts), such as quercetin and ellagic acid. In addition, we highlight the medical potential of these plant-derived compounds for treating eosinophil-mediated inflammation, such as asthma and allergy.

Anti-inflammatory effects of apigenin on nicotine- and lipopolysaccharide-stimulated human periodontal ligament cells via heme oxygenase-1

BACKGROUND AND OBJECTIVES

Although apigenin exhibits various biological effects, its anti-inflammatory role in the periodontal field remains unknown. We examined the anti-inflammatory effects of apigenin and the underlying mechanism in nicotine- and lipopolysaccharide (LPS)-stimulated human periodontal ligament (hPDL) cells.

MATERIALS AND METHODS

Western blotting was used to examine the effect of apigenin (10-40 microM) on the LPS- and nicotine-induced expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and heme oxygenase-1 (HO-1), as well as the phosphorylation of mitogen-activated protein kinases (MAPKs), in hPDL cells. Pro-inflammatory mediators, including nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-12 were monitored using Griess reagents and ELISA.

RESULTS

Incubation of hPDL cells with apigenin decreased LPS- and nicotine-induced HO-1 protein expression and activity. Apigenin significantly inhibited the nicotine- and LPS-induced production of NO, PGE2, IL-1beta, TNF-alpha, IL-6, and IL-12, and the upregulation of iNOS and COX-2 in hPDL cells. Hemin, a selective HO-1 inducer, reversed the apigenin-mediated suppression of nicotine- and LPS-induced NO, PGE2 and cytokine production. Treatment with inhibitors of the phosphoinositide 3-kinase, MAPKs, p38, and JNK, as well as a protein kinase C inhibitor, blocked the anti-inflammatory effects of apigenin in nicotine- and LPS-treated cells.

CONCLUSIONS

Apigenin possesses anti-inflammatory activity in hPDL cells and works through a novel mechanism involving the action of HO-1. Thus, apigenin may have potential benefits as a host modulatory agent in the prevention and treatment of periodontal disease associated with smoking and dental plaque.