Inhibition Of Mast Cell Activation Research Articles

Interleukin-18 binding protein regulates mast cell activation and mast cell induced osteoclastogenesis of rheumatoid arthritis.

Mast cell activation induces pathological responses, including increased osteoclastogenesis in rheumatoid arthritis (RA). Interleukin (IL)-18 binding protein (IL-18BP) has anti-inflammatory effects. In this study, we evaluated the effect of IL-18BP on mast cell activation and mast cell induced osteoclastogenesis. Mast cells were activated by IL-33 (100 ng/mL) and cultured with IL-18BP (10, 50, and 100 ng/mL). The proliferation, apoptosis, and necroptosis of mast cells were measured using flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of mast cell enzymes, matrix metalloproteinase (MMP), soluble RANKL (sRANKL), and pro-inflammatory cytokines in the culture media. Monocytes from patients with RA patients (n=5) were cultured with activated mast cells with various concentrations of IL-18BP. TRAP+ multinucleated osteoclasts, bone resorption area, and osteoclast differentiation-related genes were measured. Proliferation of tryptase+chymase+c-kit+FcεR1+ mast cells was suppressed following incubation with IL-18BP (10, 50, and 100 ng/mL). RNA expression levels of tryptase and chymase were reduced by 100 ng/mL IL-18BP. Additionally, the levels of MMP-3/9, IL-17A, IL-6, TNF-α, and sRANKL were significantly inhibited by 100 ng/mL IL-18BP. Annexin V+ and annexin V-PI+ mast cells were reduced following incubation with 100 ng/mL IL-18BP. The addition of IL-33 significantly stimulated mast cell and increased TRAP+ multinucleated cells and bone resorption area, and these effects were suppressed by IL-18BP. The osteoclast-related genes (TRAP, ATP6v0d2, RANK, and cathepsin K) expression were suppressed by IL-18BP. IL-18BP suppressed mast cell activation and mast cell induced osteoclastogenesis. This suggests a potential anti-arthritic role for IL-18BP in patients with RA.

Degranulation and expression of cytokines were modulated by diazinon in activated mast cells

Diazinon is an organophosphorus (OP) insecticides used in agriculture, home gardening and indoor pest control in Japan. It can activate macrophages and induce pro-inflammatory responses and has been reported to cause airway hyper-reactivity, suggesting the possibility of asthma exacerbation from exposure to OP insecticides. Despite the correlation between insecticide use and the pathogenesis of allergic diseases, there have been no reports on the effects of diazinon on mast cell function. Therefore, in this study, we investigated the effects of diazinon on mast cell function in rat basophilic leukemia (RBL)-2H3 cells. Surprisingly, we found that diazinon inhibited mast cell activation, although the degree of inhibition varied with concentration. Diazinon induced reactive oxygen species (ROS) generation and HO-1 expression at a concentration of 150 µM without affecting cell viability. Diazinon inhibited A23187-mediated degranulation and Tnf and Il4 expression in RBL-2H3 cells but did not affect calcium influx. Suppression of degranulation by diazinon was reversed when the culture supernatant was removed. As a signaling event downstream of calcium influx, diazinon inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) induced by A23187, whereas the phosphorylation of p38 had little effect. IgE cross-linking-mediated degranulation as well as the induction of Tnf and IL4 expression was significantly inhibited by diazinon, while diazinon had little effect on calcium influx. In conclusion, diazinon inhibited mast cell activation, including degranulation and cytokine expression. When evaluating the in vivo effects of diazinon, its potential to inhibit mast cell activation should be considered in the pathophysiology and development of allergic diseases in terms of basic and clinical aspects, respectively, although the effect of diazinon varies depending on the cell type.

Mrgprb2-mediated mast cell activation exacerbates Modic changes by regulating immune niches

Modic changes are radiographic features associated with microfracture, low-virulence organism infection and chronic inflammation with inflammatory cell infiltration in the vertebral endplate region. Mast cells, as innate immune cells similar to macrophages, are present in painful degenerated intervertebral discs. However, the involvement and mechanisms of mast cells in the development of Modic changes remain unclear. Herein, we found increased mast cell infiltration in samples from patients with Modic changes and in mouse models of Modic changes. To clarify the role of mast cells in the progression of Modic changes, we used mast cell-deficient (KITW-SH/W-SH) mice to construct a model of Modic changes and found that the severity of Modic changes in KITW-SH/W-SH mice was significantly lower than that in WT mice. These findings were further supported by the use of a mast cell-specific activator (compound 48/80) and a stabilizer (cromolyn). Furthermore, we found that mast cells were not activated via the classic IgE pathway in the Modic change models and that Mrgprb2 is the specific receptor for mast cell activation reported in recent studies. Then, we utilized Mrgprb2 knockout mice to demonstrate that Mrgprb2 knockout inhibited mast cell activation and thus reduced the degree of Modic changes. Transcriptomic sequencing revealed aberrant PI3K-AKT and MAPK pathway activation in the Mrgprb2-deficient mast cells. Additionally, Mrgpbrb2-activated mast cells regulate immune niches by recruiting macrophages, promoting M1 polarization and reducing M2 polarization, thereby promoting the progression of Modic changes. These findings suggest that mast cells may serve as a novel therapeutic target for addressing Modic changes.

Hispidulin Alleviates Mast Cell-Mediated Allergic Airway Inflammation through FcεR1 and Nrf2/HO-1 Signaling Pathway.

Allergic asthma is a type 2 immune-response-mediated chronic respiratory disease. Mast cell activation influences the pathogenesis and exacerbation of allergic asthma. Therefore, the development of mast cell-targeting pharmacotherapy is important for managing allergic airway inflammation. We investigated the efficacy of hispidulin (HPD), natural flavone, in a mast-cell-mediated ovalbumin (OVA)-induced allergic airway inflammation model. HPD alleviated symptoms of allergic asthma and decreased the levels of immunoglobulin (Ig) E, type 2 inflammation, immune cell infiltration, and mast cell activation in the lung. Furthermore, in vivo analysis confirmed the efficacy of HPD through the evaluation of IgE-mediated allergic responses in a mast cell line. HPD treatment inhibited mast cell degranulation through inhibition of the FcεR1 signaling pathway and suppressed the expression of inflammatory cytokines (TNF-α, IL-4, IL-6, and IL-13) through suppression of the NF-κB signaling pathway. The antioxidant effects of HPD in activated mast cells were identified through modulation of antioxidant enzymes and the Nrf2/HO-1 signaling pathway. In conclusion, HPD may be a potential therapeutic candidate for allergic airway inflammation of asthma and acts by suppressing mast cell activation and oxidative stress.

Stabilizing Tumor-Resident Mast Cells Restores T-Cell Infiltration and Sensitizes Sarcomas to PD-L1 Inhibition.

To explore the cellular cross-talk of tumor-resident mast cells (MC) in controlling the activity of cancer-associated fibroblasts (CAF) to overcome tumor microenvironment (TME) abnormalities, enhancing the efficacy of immune-checkpoint inhibitors in sarcoma. We used a coculture system followed by further validation in mouse models of fibrosarcoma and osteosarcoma with or without administration of the MC stabilizer and antihistamine ketotifen. To evaluate the contribution of ketotifen in sensitizing tumors to therapy, we performed combination studies with doxorubicin chemotherapy and anti-PD-L1 (B7-H1, clone 10F.9G2) treatment. We investigated the ability of ketotifen to modulate the TME in human sarcomas in the context of a repurposed phase II clinical trial. Inhibition of MC activation with ketotifen successfully suppressed CAF proliferation and stiffness of the extracellular matrix accompanied by an increase in vessel perfusion in fibrosarcoma and osteosarcoma as indicated by ultrasound shear wave elastography imaging. The improved tissue oxygenation increased the efficacy of chemoimmunotherapy, supported by enhanced T-cell infiltration and acquisition of tumor antigen-specific memory. Importantly, the effect of ketotifen in reducing tumor stiffness was further validated in sarcoma patients, highlighting its translational potential. Our study suggests the targeting of MCs with clinically administered drugs, such as antihistamines, as a promising approach to overcome resistance to immunotherapy in sarcomas.

New insights into the role of mast cells as a therapeutic target in cancer through the blockade of immune checkpoint inhibitors.

Mast cells release different anti-and pro-inflammatory agents changing their role from protective to pro-inflammatory cells involved in the progression of different pathological conditions, including autoimmune diseases and tumors. Different mediators released by mast cells are involved in their biological activities which may be anti-tumorigenic and/or pro-tumorigenic. For these reasons, tumor mast cells have been considered a novel therapeutic target to prevent tumor progression and metastatic process. Many different agents have been suggested and used in the past pre-clinical and clinical settings. Among the novel immunotherapeutic approaches to cancer treatment, different immune checkpoint inhibitors targeting PD-1/PDL-1 have been used in the treatment of many human tumors improving overall survival. In this context, inhibition of mast cell activity may be considered a novel strategy to improve the efficacy of anti-PD-1/PDL-1 therapy. The blockade of the PD-1/PD-L1 interaction may be suggested as a useful and novel therapeutic approach in the treatment of tumors in which mast cells are involved.

Marine-Derived Alternariol Monomethyl Ether Alleviates Ovalbumin-Induced Food Allergy by Suppressing MAPK and NF-κB Signaling Pathways of Mast Cells.

The prevalence of food allergies has grown dramatically over the past decade. Recently, studies have shown the potential of marine substances to alleviate food allergies. We utilized a rat basophilic leukemia (RBL)-2H3 model to evaluate the antiallergic effects of alternariol monomethyl ether (AME) extracted from marine fungi Alternaria sp. Our results showed that AME attenuated food allergy symptoms in mice and reduced histamine release in serum. The population of mast cells in the spleen and mesenteric lymph nodes was considerably reduced. Moreover, in vitro assays also revealed that AME inhibited the release of β-hexosaminidase and histamine. Transcriptomic analysis uncovered that AME regulated gene expression associated with mast cells. Additionally, Western blotting demonstrated that AME suppressed mast cell activation by modulating MAPK and NF-κB signaling pathways. Taken together, these findings provide a theoretical basis for the potential antiallergic use of marine-derived compounds in the development of functional foods.

Suppression of Mast Cell Activation by GPR35: GPR35 Is a Primary Target of Disodium Cromoglycate.

Mast cell stabilizers, including disodium cromoglycate (DSCG), were found to have potential as the agonists of an orphan G protein-coupled receptor, GPR35, although it remains to be determined whether GPR35 is expressed in mast cells and involved in suppression of mast cell degranulation. Our purpose in this study is to verify the expression of GPR35 in mast cells and to clarify how GPR35 modulates the degranulation. We explored the roles of GPR35 using an expression system, a mast cell line constitutively expressing rat GPR35, peritoneal mast cells, and bone marrow-derived cultured mast cells. Immediate allergic responses were assessed using the IgE-mediated passive cutaneous anaphylaxis (PCA) model. Various known GPR35 agonists, including DSCG and newly designed compounds, suppressed IgE-mediated degranulation. GPR35 was expressed in mature mast cells but not in immature bone marrow-derived cultured mast cells and the rat mast cell line. Degranulation induced by antigens was significantly downmodulated in the mast cell line stably expressing GPR35. A GPR35 agonist, zaprinast, induced a transient activation of RhoA and a transient decrease in the amount of filamentous actin. GPR35 agonists suppressed the PCA responses in the wild-type mice but not in the GPR35-/- mice. These findings suggest that GPR35 should prevent mast cells from undergoing degranulation induced by IgE-mediated antigen stimulation and be the primary target of mast cell stabilizers. SIGNIFICANCE STATEMENT: The agonists of an orphan G protein-coupled receptor, GPR35, including disodium cromoglycate, were found to suppress degranulation of rat and mouse mature mast cells, and their antiallergic effects were abrogated in the GPR35-/- mice, indicating that the primary target of mast cell stabilizers should be GPR35.

Melatonin inhibits mast cell activation, indicating its potential as a therapeutic agent in inflammatory diseases

Melatonin inhibits mast cell activation, indicating its potential as a therapeutic agent in inflammatory diseases

Controlled adsorption of multiple bioactive proteins enables targeted mast cell nanotherapy.

Protein adsorption onto nanomaterials often results in denaturation and loss of bioactivity. Controlling the adsorption process to maintain the protein structure and function has potential for a range of applications. Here we report that self-assembled poly(propylene sulfone) (PPSU) nanoparticles support the controlled formation of multicomponent enzyme and antibody coatings and maintain their bioactivity. Simulations indicate that hydrophobic patches on protein surfaces induce a site-specific dipole relaxation of PPSU assemblies to non-covalently anchor the proteins without disrupting the protein hydrogen bonding or structure. As a proof of concept, a nanotherapy employing multiple mast-cell-targeted antibodies for preventing anaphylaxis is demonstrated in a humanized mouse model. PPSU nanoparticles displaying an optimized ratio of co-adsorbed anti-Siglec-6 and anti-FcεRIα antibodies effectively inhibit mast cell activation and degranulation, preventing anaphylaxis. Protein immobilization on PPSU surfaces provides a simple and rapid platform for the development of targeted protein nanomedicines.

Efficacy of Shu-yi-ning-chang decoction on IBS-D: Modulating Nr4a3 pathway to reduce visceral hypersensitivity.

To evaluate the therapeutic effect of SYNC in diarrhea irritable bowel syndrome (IBS-D) and explore its underlying mechanism through transcriptomic sequencing (RNA-Seq). A rat model of IBS-D was constructed to elucidate the effects of SYNC. Abdominal withdrawal reflex (AWR), fecal water content (FWC), and recording body weight were calculated to assess visceral sensitivity in rats. Histopathological changes in the colon and alterations in mast cell (MC) count were determined. Immunohistochemistry was employed to assess mast cell tryptase (MCT) expression in rat colons. Serum levels of corticotropin-releasing Hormone (CRH), interleukin-6 (IL-6), calcitonin gene-related peptide (CGRP), and 5-hydroxytryptamine (5-HT) were quantified using ELISA. RNA-Seq of colon tissue was performed, followed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Western blot analysis was conducted to quantify the expression levels of key proteins in the Nr4a3 pathway in the colon and hypothalamus tissues of rats. SYNC alleviated visceral hypersensitivity and mood disorders in rats with IBS-D. Moreover, it was positively correlated with its dosage and the observed effects, such as the enhancement of the colon's mucosal lining condition and reduction in the number and activation of MCs within the model group. SYNC reduced the expression levels of factors related to the brain-gut axis and inflammatory markers in the bloodstream. RNA-Seq analysis indicated that SYNC down-regulated the expression of Nr4a3 and PI3K. These SYNC-targeted genes primarily played roles in immune regulation and inflammatory responses, correlating with the modulation of Nr4a3 and the PI3K/AKT pathway. Western blot analysis further confirmed SYNC's influence on inflammation-related MC activation by downregulating key proteins in the Nr4a3/PI3K pathway. SYNC inhibited mast cell activation and attenuated visceral hypersensitivity in the colon tissues of IBS-D rats. These effects were mediated by the Nr4a3/PI3K signaling pathway.

Butyrate interacts with the effects of 2'FL and 3FL to modulate in vitro ovalbumin-induced immune activation, and 2'FL lowers mucosal mast cell activation in a preclinical model for hen's egg allergy.

Early life provides a window of opportunity to prevent allergic diseases. With a prevalence of 0.5-2% in infants, hen's egg allergy is one of the most common food allergies. The immunomodulatory effects of human milk oligosaccharides (HMOs), 2'-fucosyllactose (2'FL), and 3-fucosyllactose (3FL) were studied in an in vitro mucosal immune model and an in vivo murine model for hen's egg (ovalbumin) allergy. Intestinal epithelial cell (IEC)/dendritic cell (DC) and DC/T cell cocultures were used to expose IECs to ovalbumin (OVA) in an in vitro mucosal immune model. The effects of epithelial pre-incubation with 0.1% 2'FL or 3FL and/or 0.5 mM butyrate were studied. Three- to four-weeks-old female C3H/HeOuJ mice were fed AIN93G diets containing 0.1-0.5% 2'FL or 3FL 2 weeks before and during OVA sensitization and challenge. Allergic symptoms and systemic and local immune parameters were assessed. Exposing IECs to butyrate in vitro left the IEC/DC/T cell cross-talk unaffected, while 2'FL and 3FL showed differential immunomodulatory effects. In 3FL exposed IEC-DC-T cells, the secretion of IFNγ and IL10 was enhanced. This was observed upon pre-incubation of IECs with 2'FL and butyrate as well, but not 2'FL alone. The presence of butyrate did not affect OVA activation, but when combined with 3FL, an increase in IL6 release from DCs was observed (p < 0.001). OVA allergic mice receiving 0.5% 3FL diet had a lower %Th2 cells in MLNs, but the humoral response was unaltered compared to control mice. OVA-allergic mice receiving 0.1 or 0.5% 2'FL diets had lower serum levels of OVA-IgG2a (p < 0.05) or the mast cell marker mMCP1, in association with increased concentration of cecal short-chain fatty acids (SCFAs) (p < 0.05). In vitro butyrate exposure promotes the development of a downstream type 1 and regulatory response observed after 2'FL exposure. 2'FL and 3FL differentially modulate ovalbumin-induced mucosal inflammation predominantly independent of butyrate. Mice receiving dietary 3FL during ovalbumin sensitization and challenge had lowered Th2 activation while the frequency of Treg cells was enhanced. By contrast, 2'FL improved the humoral immune response and suppressed mast cell activation in association with increased SCFAs production in the murine model for hen's egg allergy.

Mechanism of analgesic effect of fire needle on peripheral sensitization in rats with neuropathic pain induced by chemotherapy.

This study aims to explore the analgesic mechanism of fire needle on peripheral sensitization in rats with neuropathic pain(NP) induced by oxaliplatin, so as to investigate its mechanism in improving peri-pheral sensitization. Male SD rats aged 8 weeks were randomly divided into 4 groups：normal group(n=6), model group(n=6), fire needle group(n=6), and medication group(n=6). NP rat model was established by intraperitoneal injection of oxaliplatin(4 mg/kg) on days 1, 2, 8, 9, 15, 16, 22, and 23. For rats in the fire needle group, fire needle treatment was performed at the "Jiaji"(EX-B2) acupoints of the L4-L6 segments on days 24, 26, and 28, ie. 1 day, 3 and 5 days after modeling. The medication group received intraperitoneal injection of pregabalin(100 mg/kg). Mechanical pain thresholds of the rats were measured before modeling, after modeling and intervention. Serum contents of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) and chemokine ligand 12(CXCL12) were detected by ELISA. Skin histopathology changes in the acupoint area were observed using HE staining. The number of mast cells in the skin of the acupoints was observed using toluidine blue staining. Immunohistochemical staining was performed to detect the postive expressions of transient receptor potential vanilloid 1(TRPV1), protease-activated receptor 2(PAR2) and tryptase(TPS) in the skin of the acupoint area. Western blot was used to detect the protein expressions of TRPV1 and PAR2 in the dorsal root ganglia(DRG). Compared with the normal group, the model group had decreased paw withdrawal threshold(PWT) after modeling(P<0.05), increased serum contents of IL-6, TNF-α, and CXCL12(P<0.05), increased number of mast cells in the acupoint area(P<0.05), and increased positive protein expressions of TPS, TRPV1, and PAR2 in the skin of the acupoint area(P<0.05). Compared with the model group, the fire needle group and medication group had increased PWT after intervention(P<0.05), decreased serum contents of IL-6, TNF-α, and CXCL12, and postive protein expressions of TPS, TRPV1, and PAR2 in the skin of the acupoint area(P<0.05)；while the medication group had decreased protein expressions of TRPV1 and PAR2 in DRG(P<0.05). HE staining showed thickened epidermis, disordered cellular arrangement, significant intercellular edema, and inflammatory cell infiltration in the model group. In the medication and fire needle groups, the epidermis was thinner, cellular arrangement was clearer, and the extent of tissue edema and inflammatory cell infiltration was reduced compared to the model group. Fire needle can improve mechanical pain threshold and reduce the contents of peripheral inflammatory factors in rats with oxaliplatin-induced NP. This effect may be related to the inhibition of mast cell activation and the inhibition of TPS, TRPV1 and PAR2 protein expressions, in the local areas of acupoints.

Apigenin attenuates visceral hypersensitivity in water avoidance stress rats by modulating the microbiota-gut-brain axis and inhibiting mast cell activation

Visceral hypersensitivity (VH) and gut microbiota dysbiosis significantly contribute to the occurrence and development of irritable bowel syndrome (IBS), exacerbated by stress. Apigenin, a natural flavonoid derived from plants, possesses a range of beneficial properties. However, additional research is necessary to investigate its potential in alleviating symptoms of IBS and elucidating its underlying mechanisms of action. Our study confirms that apigenin effectively reverses mast cell and microglial activation, regulates the composition and abundance of the gut microbiota, improves intestinal barrier function in rats induced with water-avoidance stress, and mitigates VH and colonic hypermotility. Furthermore, in vitro studies suggest a potential role of dysbiotic gut microbiota in activating mast cells at the cellular level. Notably, apigenin inhibits mast cell degranulation through the toll-like receptor 4 (TLR4) / myeloid differentiation primary response gene 88 (MyD88) / nuclear factor-kappa B (NF-κB) pathway. In conclusion, this study discusses the potential therapeutic effects of apigenin in alleviating VH and modulating the gut-brain axis in water-avoidance stress rats, providing a novel or alternative treatment approach for IBS.

Fluoxetine restrains allergic inflammation by targeting an FcɛRI-ATP positive feedback loop in mast cells.

There is a clinical need for new treatment options addressing allergic disease. Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that have anti-inflammatory properties. We tested the effects of the SSRI fluoxetine on IgE-induced function of mast cells, which are critical effectors of allergic inflammation. We showed that fluoxetine treatment of murine or human mast cells reduced IgE-mediated degranulation, cytokine production, and inflammatory lipid secretion, as well as signaling mediated by the mast cell activator ATP. In a mouse model of systemic anaphylaxis, fluoxetine reduced hypothermia and cytokine production. Fluoxetine was also effective in a model of allergic airway inflammation, where it reduced bronchial responsiveness and inflammation. These data show that fluoxetine suppresses mast cell activation by impeding an FcɛRI-ATP positive feedback loop and support the potential repurposing of this SSRI for use in allergic disease.

5-Hydroxymethylfurfural Ameliorates Allergic Inflammation in HMC-1 Cells by Inactivating NF-κB and MAPK Signaling Pathways.

Allergic inflammation is the foundation of multiple allergic disorders, such as allergic rhinitis and asthma. Mast cells are effector cells that initiate inflammatory response. 5-hydroxymethylfurfural (5-HMF), a furfural compound, is the heat-processed product of various fruit, foods, drinks, as well as some Chinese herbal medicines. 5-HMF was previously reported to inhibit mast cell activation. Our study aimed to explore the functions of 5-HMF in both phorbol 12-mystate 13-acetate (PMA) plus calcium ionophore (A23187)-induced allergic inflammation in human mast cell line HMC-1 and ovalbumin (OVA)-induced asthma mouse models. HMC-1 cells were pretreated with 5-HMF and then stimulated by PMA+A23187. The cytotoxicity of 5-HMF on HMC-1 cells was evaluated by MTT assay. Histamine content in cell supernatants was measured by the o-phthaldialdehyde spectrofluorometric procedure. Intracellular calcium was determined using the fluorescent dye Fura-2AM. The production and expression of pro-inflammatory cytokines were detected by ELISA and RT-qPCR. Caspase-1 colorimetric assay was employed to examine the enzymatic activity of caspase-1. Asthma mouse models were induced by OVA sensitization. The bronchoalveolar lavage fluid (BALF) and blood samples were collected for the detection of total and differential cell count as well as aspartate aminotransferase (AST), alanine aminotransferase (ALT), OVA-immunoglobulin E (OVA-IgE), OVA-immunoglobulin G1 (OVA-IgG1), and pro-inflammatory cytokine levels. The left lung of mouse was dissected for histopathological examination by hematoxylin and eosin (H&E) staining. The protein expression of pro-caspase-1 and the phosphorylation of NF-κB and MAPK pathway-associated molecules were assessed by Western blotting. Our findings revealed that 5-HMF efficiently suppressed the PMA+A23187-induced enhancement in histamine production and intracellular calcium in HMC-1 cells. Pro-inflammatory cytokine production and expression in HMC-1 cells were elevated after PMA plus A23187 stimulation, which, however, were inhibited by pretreatment of 5-HMF. Additionally, 5-HMF suppressed the activity of caspase-1 and the phosphorylation of NF-κB and MAPK-associatedmolecules including p65 NF-κB, p38 MAPK, ERK, and JNK in HMC-1 cells. In vivo experiments demonstrated that 5-HMF treatment reduced the lung/body weight index and total and differential (macrophages, neutrophils, lymphocytes, and eosinophils) cell counts in BALF of asthmatic mice, but exerted no influence on serum AST and ALT levels. Besides, 5-HMF reduced serum OVA-IgE and OVA-IgG1 levels, mitigated lung inflammation, and inhibited the NF-κB and MAPK signaling pathways in asthma mouse models. 5-HMF mitigates allergic inflammation in asthma by inactivating caspase-1 and NF-κB and MAPK signaling pathways.

Effects of total alkaloids from Alstonia scholaris (L.) R. Br. on ovalbumin-induced asthma mice

Ethnopharmacological relevanceMore than 300 million people worldwide suffer from asthma, a chronic respiratory inflammatory disease. Total alkaloids (TA) were extracted from the ethnic medicinal plant Alstonia solaris (L.) R.Br., which is used to treat respiratory diseases. They may be effective drugs for treating asthma, but research is still needed to determine their effectiveness and mechanism in treating asthma. Aim of the studyTo further understand TA's role in the treatment of asthma and to support the phase II trial of the drug. Materials and methodsIn this study, we investigated the effects of TA in a mouse asthma model produced by Ovalbumin (OVA). H&E and PAS staining were used to observe the histopathological features of lung. airway hyperresponsiveness (AHR) was detected by ventilator; The expression of interleukin (IL)-33, suppression of tumorigenicity 2 (ST2) and E-cadherin in the lungs was evaluated by IHC. The concentrations of Mucin5AC (MUC5AC), eotaxin, IL-4, IL-5, IL-9, IL-13, interferon (IFN)-γ, IL-6, IL-8, IL-17A, IL-33, IL-25, thymic stromal lymphopoietin (TSLP), monocyte chemoattractant protein 1 (MCP-1), leukotriene (LT) B4, LTC4, LTD4, LTE4 in bronchoalveolar lavage fluid (BALF) and total IgE (tIgE), OVA-Specific IgE (OVA-IgE) in serum were measured by ELISA. ILC2s and eosinophils were detected in lung tissue by flow cytometry. The gene expression levels of IL-33 and ST2 were detected by RT-qPCR. ResultsAdministration of TA reduced pulmonary inflammatory symptoms, MUC5AC production in the BALF, and AHR. At the same time, TA inhibited eotaxin production and eosinophil recruitment. Moreover, TA significantly decreased Th2 and Th17 cytokines and increased Th1 cytokines, contributing to restore the balance between Th1 and Th2 and Th17 cytokines. TA may reduce ILC2s numbers by inhibiting IL-33, IL-25, and TSLP levels in BALF and IL-33/ST2 signaling in lung tissue. Finally, TA decreased tIgE, OVA-IgE, and MCP-1 levels and subsequently inhibited mast cell activation and leukotriene release. ConclusionsThese findings imply that TA may be an effective immunoregulatory medication for the management and prevention of asthma.

Translational Selenium Nanoparticles to Attenuate Allergic Dermatitis through Nrf2-Keap1-Driven Activation of Selenoproteins.

Easy recurrence and strong treatment side effects significantly limit the clinical treatment of allergic dermatitis. The human trace element selenium (Se) plays essential roles in redox regulation through incorporation into selenoproteins in the form of 21st necessary amino acid selenocysteine, to participates in the pathogenesis and intervention of chronic inflammatory diseases. Therefore, based on the safe and elemental properties of Se, we construct a facile-synthesis strategy for antiallergic selenium nanoparticles (LET-SeNPs), and scale up the production by employing a spray drying method with lactose (Lac-LET-SeNPs) or maltodextrin (Mal-LET-SeNPs) as encapsulation agents realizing larger scale production and a longer storage time. As expected, these as-prepared LET-SeNPs could effectively activate the Nrf2-Keap1 signaling pathway to enhance the expression of antioxidative selenoprotein at mRNA and protein levels, then inhibit mast cell activation to achieve efficient antiallergic activity. Interestingly, LET-SeNPs undergo metabolism to seleno-amino acids to promote biosynthesis of selenoproteins, which could suppress ROS-induced cyclooxygenase-2 (COX-2) and MAPKs activation to suppress the release of histamine and inflammatory cytokines. Allergic mouse and Macaca fascicularis models further confirm that LET-SeNPs could increase the Se content and selenoprotein expression in the skin, decrease mast cells activation and inflammatory cells infiltration, and finally exhibit the high therapeutic effects on allergic dermatitis. Taken together, this study not only constructs facile large-scale synthesis of translational Se nanomedicine to break through the bottleneck problem of nanomaterials but also sheds light on its application in the intervention and treatment of allergies.

CKBA suppresses mast cell activation via ERK signaling pathway in murine atopic dermatitis.

Atopic dermatitis (AD) is a common inflammatory skin disorder. Mast cells play an important role in AD because they regulate allergic reactions and inflammatory responses. However, whether and how the modulation of mast cell activity affects AD has not been determined. In this study, we aimed to determine the effects and mechanisms of 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid (CKBA). This natural compound derivative alleviates skin inflammation by inhibiting mast cell activation and maintaining skin barrier homeostasis in AD. CKBA markedly reduced serum IgE levels and alleviated skin inflammation in calcipotriol (MC903)-induced AD mouse model. CKBA also restrained mast cell degranulation both in vitro and in vivo. RNA-seq analysis revealed that CKBA downregulated the extracellular signal-regulated kinase (ERK) signaling in BM-derived mast cells activated by anti-2,4-dinitrophenol/2,4-dinitrophenol-human serum albumin. We proved that CKBA suppressed mast cell activation via ERK signaling using the ERK activator (t-butyl hydroquinone) and inhibitor (selumetinib; AZD6244) in AD. Thus, CKBA suppressed mast cell activation in AD via the ERK signaling pathway and could be a therapeutic candidate drug for AD.

Fisetin alleviates chronic urticaria by inhibiting mast cell activation via MRGPRX2.

The activation of mast cell (MC) plays an important part in the pathogenesis of chronic urticaria (CU), and the expression of MRGPRX2 (Mas-related G-protein coupled receptor X2) and the circulating levels of SP (substance P) in skin MC of CU patients increased. Fisetin is a natural flavonoid with anti-inflammatory and antiallergic pharmacological effects. This study aimed to investigate the inhibitory effect of fisetin on CU via MRGPRX2 and its possible molecular mechanisms. OVA/SP co-stimulated and SP-stimulated CU like murine models were used to evaluate the effect of fisetin on CU. MRGPRX2/HEK293 cells and LAD2 cells were used to perform the antagonism effect of fisetin on MC via MRGPRX2. The results indicated that fisetin prevented urticaria-like symptoms in murine CU models, and inhibited MCs activation by suppressing calcium mobilization and degranulation of cytokines and chemokines via binding to MRGPRX2. The bioinformatics analysis showed that fisetin might have an interaction relationship with Akt in CU. The western blotting experiments showed that fisetin downregulated the phosphorylation levels of Akt, P38, NF-κB, and PLCγ in C48/80 activated LAD2 cells. Fisetin alleviates CU progression by inhibiting mast cell activation via MRGPRX2, which may be a novel therapeutic candidate for CU.