SG-SP1 Suppresses Mast Cell-Mediated Allergic Inflammation via Inhibition of FcεRI Signaling

Ethanol Extract of Ampelopsis brevipedunculata Rhizomes Suppresses IgE-Mediated Mast Cell Activation and Anaphylaxis

More than 20% of the world's population suffers from allergic diseases, including allergic asthma, rhinitis, and atopic dermatitis that severely reduce the patient's quality of life. The treatment of allergy has been developed, but there are still unmet needs. Ampelopsis brevipedunculata (Maxim.) Trautv. is a traditional medicinal herb with beneficial bioactivities, such as antioxidant, anti-hypertension, anti-viral, anti-mutagenic, and skin and liver (anti-hepatotoxic) protective actions. However, its anti-allergic effect has not been addressed. This study designed to investigate the pharmacological effect of an ethanol extract of A. brevipedunculata rhizomes (ABE) on mast cell and anaphylaxis models. For in vivo studies, we used ovalbumin-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models. In ASA model, oral administration of ABE (1, 10, and 100 mg/kg) attenuated the anaphylactic responses, such as hypothermia, serum histamine, and IgE productions. In PCA model, ABE also suppressed the plasma extravasation and swelling. The underlying mechanisms of action were identified in various mast cell types. In vitro, ABE (10, 30, and 60 µg/mL) inhibited the release of essential allergic mediators, such as histamine and β-hexosaminidase, in a concentration-dependent manner. ABE prevented the rapid increase in intracellular calcium levels induced by the DNP-HSA challenge. In addition, ABE downregulated the tumor necrosis factor-α and interleukin-4 by suppressing the activation of nuclear factor-κB. Collectively, this study is the first to identify the anti-allergic effect of ABE, suggesting that ABE is a promising candidate for treating allergic diseases.

Dietary Polyphenols-Natural Bioactive Compounds with Potential for Preventing and Treating Some Allergic Conditions

In light of the constantly increasing prevalence of allergic diseases, changes in dietary patterns have been suggested as a plausible environmental explanation for the development and progression of these diseases. Nowadays, much attention has been paid to the development of dietary interventions using natural substances with anti-allergy activities. In this respect, dietary polyphenols have been studied extensively as one of the most prominent natural bioactive compounds with well-documented anti-inflammatory, antioxidant, and immunomodulatory properties. This review aims to discuss the mechanisms underlying the potential anti-allergic actions of polyphenols related to their ability to reduce protein allergenicity, regulate immune response, and gut microbiome modification; however, these issues need to be elucidated in detail. This paper reviews the current evidence from experimental and clinical studies confirming that various polyphenols such as quercetin, curcumin, resveratrol, catechins, and many others could attenuate allergic inflammation, alleviate the symptoms of food allergy, asthma, and allergic rhinitis, and prevent the development of allergic immune response. Conclusively, dietary polyphenols are endowed with great anti-allergic potential and therefore could be used either for preventive approaches or therapeutic interventions in relation to allergic diseases. Limitations in studying and widespread use of polyphenols as well as future research directions are also discussed.

Anti-inflammatory effect of dictamnine on allergic rhinitis via suppression of the LYN kinase-mediated molecular signaling pathway during mast cell activation

Mast cells (MCs) are important therapeutic targets for allergic diseases. High-affinity immunoglobulin E (IgE) Fc receptors (FcεRI) trigger abnormal activation of MCs. Allergic rhinitis (AR) is an IgE-mediated antigen inhalation reaction that occurs in the nasal mucosa. MC aggravation and dysfunction were observed during the early stages of AR pathogenesis. Herb-derived dictamnine exhibits anti-inflammatory effects. Here, we investigated the pharmacological effects of herb-derived dictamnine on IgE-induced activation of MCs and an ovalbumin (OVA)-induced murine AR model. The results indicated that dictamnine attenuated OVA-induced local allergic reactions and reduced body temperature in OVA-challenged mice with active systemic anaphylaxis. Additionally, dictamnine decreased the frequency of nasal rubbing and sneezing in an OVA-induced murine AR model. Moreover, dictamnine inhibited FcεRI-activated MC activation in a dose-dependent manner without causing cytotoxicity, reduced the activation of the tyrosine kinase LYN in LAD2 cells, and downregulated the phosphorylation of PLCγ1, IP3R, PKC, Erk1/2, and Akt, which are downstream of LYN. In conclusion, dictamnine suppressed the OVA-stimulated murine model of AR and activated IgE-induced MCs via the LYN kinase-mediated molecular signaling pathway, suggesting that dictamnine may be a promising treatment for AR.

Allergic Rhinitis: Pathophysiology and Treatment Focusing on Mast Cells

Allergic rhinitis (AR) is a common rhinopathy that affects up to 30% of the adult population. It is defined as an inflammation of the nasal mucosa, develops in allergic individuals, and is detected mostly by a positive skin-prick test. AR is characterized by a triad of nasal congestion, rhinorrhea, and sneezing. Mast cells (MCs) are innate immune system effector cells that play a pivotal role in innate immunity and modulating adaptive immunity, rendering them as key cells of allergic inflammation and thus of allergic diseases. MCs are typically located in body surfaces exposed to the external environment such as the nasal mucosa. Due to their location in the nasal mucosa, they are in the first line of defense against inhaled substances such as allergens. IgE-dependent activation of MCs in the nasal mucosa following exposure to allergens in a sensitized individual is a cardinal mechanism in the pathophysiology of AR. This review is a comprehensive summary of MCs' involvement in the development of AR symptoms and how classical AR medications, as well as emerging AR therapies, modulate MCs and MC-derived mediators involved in the development of AR.

Systematic comparisons of various markers for mast cell activation in RBL-2H3 cells

Mast cell activation plays a key role in various allergic diseases and anaphylaxis. Several methods/techniques can be used for detection of mast cell activation. However, there was no previous systematic evaluation to compare the efficacy of each method/technique. The present study thus systematically compared various markers for mast cell activation induced by IgE cross-linking. The widely used RBL-2H3 mast cells were sensitized with anti-DNP (dinitrophenyl) IgE overnight and activated with DNP-BSA (bovine serum albumin) for up to 4 h. The untreated cells and those with anti-DNP IgE sensitization but without DNP-BSA activation served as the controls. Intracellular calcium level gradually increased to ~2-fold at 1 h, reached its peak (~5-fold) at 2 h, and returned to the basal level at 3-h post-activation. The increases in cellular tryptase level (by Western blotting) (~0.3- to 0.4-fold) and average cell size (~2.5-fold) and decrease of nucleus/cytoplasm ratio (~0.4- to 0.5-fold) were marginal at all time-points. By contrast, β-hexosaminidase release and CD63 expression (by both flow cytometry and immunofluorescence detection/localization), secreted tryptase level (by Western blotting), and tryptase expression (by immunofluorescence detection/localization) stably and obviously increased (~10-fold as compared with the untreated control and sensitized-only cells or detectable only after activation). Based on these data, the stably obvious increases (by ≥ 10-fold) in β-hexosaminidase release, CD63 expression (by both flow cytometry and immunofluorescence staining), secreted tryptase level (by Western blotting), and tryptase expression (by immunofluorescence staining) are recommended as the markers of choice for the in vitro study of mast cell activation using RBL-2H3 cells.

Greater Plasma Protein Adsorption on Mesoporous Silica Nanoparticles Aggravates Atopic Dermatitis

Purpose

The protein corona surrounding nanoparticles has attracted considerable attention as it induces subsequent inflammatory responses. Although mesoporous silica nanoparticles (MSN) are commonly used in medicines, cosmetics, and packaging, the inflammatory effects of the MSN protein corona on the cutaneous system have not been investigated till date.

Methods

We examined the greater plasma protein adsorption on MSN leads to serious inflammatory reactions in Dermatophagoides farinae extract (DFE)-induced mouse atopic dermatitis (AD)-like skin inflammation because of increased uptake by keratinocytes.

Results

We compare the AD lesions induced by MSN and colloidal (non-porous) silica nanoparticles (CSN), which exhibit different pore architectures but similar dimensions and surface chemistry. MSN-corona treatment of severe skin inflammation in a DFE-induced in vivo AD model greatly increases mouse ear epidermal thickness and infiltration of immune cells compared with the CSN-corona treatment. Moreover, MSN-corona significantly increase AD-specific immunoglobulins, serum histamine, and Th1/Th2/Th17 cytokines in the ear and lymph nodes. MSN-corona induce more severe cutaneous inflammation than CSN by significantly decreasing claudin-1 expression.

Conclusion

This study demonstrates the novel impact of the MSN protein corona in inducing inflammatory responses through claudin-1 downregulation and suggests useful clinical guidelines for MSN application in cosmetics and drug delivery systems.

A sensitive analytical method for the determination of SG-SP1 in rat plasma by HPLC-MS/MS and its application to a pharmacokinetic study

SG-SP1, a newly synthesised gallic acid derivative, blocks histamine release by reducing calcium influx in mast cells and inhibits inflammatory cytokine expression. This derivative has promising anti-allergic potential. Our research was designed to establish a quantitative determination method for SG-SP1 in rat plasma using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), to validate the analytical method including stability and to characterise its pharmacokinetic behaviour in rats. After simple protein precipitation with acetonitrile including an internal standard, SG-SP1 was eluted on a reversed-phase column using a mobile phase of water and acetonitrile (2:8 v/v, including 0.1 % formic acid). The protonated precursor ion [M+H]⁺ and major fragment ion were confirmed at m/z 588.2 and 180.1, respectively. The substance was stable under bench and storage conditions. The analytical method met the criteria of FDA-validated bioanalytical methods and was successfully applied to a pharmacokinetic study for the first time. SG-SP1 decayed in a biphasic pattern with terminal half-life of 5.1 h and clearance of about 3.2 L/h/kg. Double peaks were observed following oral administration, and the absolute oral bioavailability was ∼1 %.

Glaucocalyxin A Attenuates Allergic Responses by Inhibiting Mast Cell Degranulation through p38MAPK/NrF2/HO-1 and HMGB1/TLR4/NF-κB Signaling Pathways

Glaucocalyxin A (GLA) has various pharmacological effects like antioxidation, immune regulation, and antiatherosclerosis. Here, in this study, the effect and mechanism of GLA on mast cell degranulation were studied. The results of the anti-DNP IgE-mediated passive cutaneous anaphylaxis (PCA) showed that GLA dramatically inhibited PCA in vivo, as evidenced by reduced Evans blue extravasation and decreased ear thickness. In addition, GLA significantly reduced the release of histamine and β-hexosaminidase, calcium influx, cytokine (IL-4, TNF-α, IL-1β, IL-13, and IL-8) production in the RBL-2H3 (rat basophilic leukemia cells), and RPMCs (peritoneal mast cells) in vitro. Moreover, we further investigated the regulatory mechanism of GLA on antigen-induced mast cells by Western blot, which showed that GLA inhibited FcεRI-mediated signal transduction and invalidated the phosphorylation of Syk, Fyn, Lyn, Gab2, and PLC-γ1. In addition, GLA inhibited the recombinant mouse high mobility group protein B1- (HMGB1-) induced mast cell degranulation through limiting nuclear translocation of NF-κBp65. Treatment of mast cells with siRNA-HMGB1 significantly inhibited HMGB1 levels, as well as MyD88 and TLR4, decreased intracellular calcium levels, and suppressed the release of β-hexosaminidase. Meanwhile, GLA increased NrF2 and HO-1 levels by activating p38MAPK phosphorylation. Consequently, these data suggest that GLA regulates the NrF2/HO-1 signaling pathway through p38MAPK phosphorylation and inhibits HMGB1/TLR4/NF-κB signaling pathway to reduce mast cell degranulation and allergic inflammation. Our findings could be used as a promising therapeutic drug against allergic inflammatory disease.

Opportunities and challenges for the nanodelivery of green tea catechins in functional foods

Green tea, the least processed tea product, is scientifically known for its rich antioxidant content originating from polyphenols, especially catechins. The most potent green tea catechin is epigallocatechin-3-gallate (EGCG), which is responsible for a wide range of health benefits including anticancer, antidiabetics, and anti-inflammatory properties. However, green tea catechins (GTCs) are very labile under both environmental and gastrointestinal conditions; their chemical stability and bioavailability primarily depend on the processing and formulation conditions. Nanocarriers can protect GTCs against such conditions, and consequently, can be applicable for designing nanodelivery systems suitable for GTCs. In this review, the latest findings about both opportunities and limitations for the nanodelivery of GTCs and their incorporation into various functional food products are discussed. The scientific findings so far confirm that nanodelivery of GTCs can be an efficient approach towards the enhancement of their health-promoting effects with a minimal dose, controlled and targeted release, lessening the dose-related toxicity, and the efficient incorporation into functional foods. However, further investigation is yet needed to fully explain the cellular mechanisms of action of GTCs on human health and to elucidate the effect of encapsulation on their bioefficacy using well-designed, systematic, long-term, and large-scale clinical interventions. There also exists a substantial concern regarding the safety of the manufactured nanoparticles, their absorption, and the associated release mechanisms.

The anti-allergic potential of tea: a review of its components, mechanisms and risks

Allergy is an immune-mediated disease with increasing prevalence worldwide. Regular treatment with glucocorticoids and antihistamine drugs for allergy patients is palliative rather than permanent. Daily use of dietary anti-allergic natural products is a superior way to prevent allergy and alleviate the threat. Tea, as a health-promoting beverage, has multiple compounds with immunomodulatory ability. Persuasive evidence has shown the anti-allergic ability of tea against asthma, food allergy, atopic dermatitis and anaphylaxis. Recent advances in potential anti-allergic ability of tea and anti-allergic compounds in tea have been reviewed in this paper. Tea exerts its anti-allergic effect mainly by reducing IgE and histamine levels, decreasing FcεRI expression, regulating the balance of Th1/Th2/Th17/Treg cells and inhibiting related transcription factors. Further research perspectives are also discussed.

Inhibitory Effects of Eriodictyol-7-O-β-d-glucuronide and 5,7-Dihydroxy-4-chromene Isolated from Chrysanthemum zawadskii var. latilobum in FcεRI-Mediated Human Basophilic KU812F Cell Activation

Chrysanthemum zawadskii var. latilobum (CZL) has been used in Eastern medicine for the treatment of various diseases, such as pneumonia, bronchitis, cough, the common cold, pharyngitis, bladder-related disorders, gastroenteric disorders, and hypertension. In the present study, we isolated two strong antiallergic compounds from CZL, namely, eriodictyol-7-O-β-d-glucuronide (EDG) and 5,7-dihydroxy-4-chromene (DC), and investigated their antiallergic effects in FcεRI-mediated human basophilic KU812F cells. EDG and DC downregulated the protein and messenger RNA (mRNA) expression of FcεRI on the cell surface. Moreover, Western blotting analysis showed that EDG and DC inhibited the expression of protein tyrosine kinases such as Syk and Lyn, and extracellular-regulated kinases (ERK) 1/2. These results suggested that EDG and DC, antiallergic constituents of CZL, are potential therapeutic candidates for protection against and for the treatment of allergic disorders.