Morus bombycis extract suppresses mast cell activation and IgE-mediated allergic reaction in mice

Protective effect of Achyranthes aspera against compound 48/80, histamine and ovalbumin-induced allergic disorders in murine model

BACKGROUND

Achyranthes aspera L. (family Amaranthaceae) is a plant species valued in Ayurveda for the treatment of respiratory ailments. Scientific validation of its antiallergic potential was aimed.

METHODS AND RESULTS

Three extracts of A. aspera [aqueous (AaAq), hydroalcoholic (AaHA), ethanolic (AaEt)] were evaluated for their potency against C48/80-induced anaphylaxis in mice at 200 mg/kg BW oral dose. The effective dose of the most potent extract was determined through its effect on C48/80-induced anaphylaxis, and was further analyzed through its effect on mast cell degranulation, histamine-induced bronchospasm and ovalbumin (OVA)-induced asthma in a murine model. Among the three extracts, AaAq was found to be most potent at 200 mg/kg BW. AaAq 400 (400 mg/kg BW) was found to be the most effective dose in terms of inhibition of mortality and histamine level. AaAq 400 prevented the peritoneal and mesenteric mast cells from undergoing morphological changes due to degranulation induced by C48/80. Further, AaAq 400 delayed pre-convulsive time in histamine-induced bronchospasm. In the OVA-induced asthma model, AaAq 400 inhibited the level of inflammatory cell count in blood, bronchoalveolar lavage fluid and peritoneal fluid of mice. The Th2 cytokines (IL-4, IL-5, IL-13), TGF-β and OVA-specific IgE were also reduced as evaluated by ELISA. Also, significant reduction in IL-5 (an eosinophilia indicator) transcript abundance and lung inflammatory score was observed. AaAq was safe up to 4000 mg/kg BW.

CONCLUSIONS

Thus AaAq 400 possesses significant antiallergic potential and acts via attenuation of C48/80-induced anaphylaxis and inhibition of mast cell degranulation. It reduces pre-convulsive dyspnea in histamine-induced bronchospasm and Th2 cytokines in asthmatic mice.

Anti-Inflammatory Herbal Extracts and Their Drug Discovery Perspective in Atopic Dermatitis

Atopic dermatitis (AD) is an allergic disorder characterized by skin inflammation. It is well known that the activation of various inflammatory cells and the generation of inflammatory molecules are closely linked to the development of AD. There is accumulating evidence demonstrating the beneficial effects of herbal extracts (HEs) on the regulation of inflammatory response in both in vitro and in vivo studies of AD. This review summarizes the anti-atopic effects of HEs and its associated underlying mechanisms, with a brief introduction of in vitro and in vivo experiment models of AD based on previous and recent studies. Thus, this review confirms the utility of HEs for AD therapy.

A TCM formula VYAC ameliorates DNCB-induced atopic dermatitis via blocking mast cell degranulation and suppressing NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

A Traditional Chinese Medicine (TCM) formula (VYAC) consists of three herbs including Viola yedoensis Makino, herb (Violaceae, Viola), Sophora flavescens Aiton, root (Fabaceae, Sophora) and Dictamnus dasycarpus Turcz, root and rhizome (Rutaceae, Dictamnus), has been traditionally prescribed to treat various skin diseases in clinic.

AIM OF THE STUDY

This study aims to investigate the therapeutic effects of VYAC on the 2,4-dinitrobenzene (DNCB) induced atopic dermatitis (AD)-like mice and to explore the underlying mechanisms.

MATERIALS AND METHODS

VYAC was extracted with 70 % aqueous ethanol and lyophilized powder was used. AD-like mice were challenged by DNCB, VYAC (150 and 300 mg/kg) were oral administration daily from day 7 to day 28. At the end of experiment, the clinical scores were recorded, serum and skin in the dorsal were isolated to evaluate the therapeutic effects of VYAC. RBL-2H3 cells were stimulated with C48/80 for degranulation and plasmids expressing constitutively active form of Syk (Silence or overexpression) were transfected into RBL-2H3 cells to explore the underlying mechanisms in vitro.

RESULTS

VYAC significantly ameliorated the cardinal symptoms in the DNCB-induced AD-like mice by repairing the skin barrier function, inhibiting mast cells infiltration, restraining the serum IgE and histamine release and decreasing TNF-α, IL-4 as well as Syk mRNA level in dorsal skin and alleviating inflammation. Besides, VYAC significantly blocked RBL-2H3 cells degranulation, reduced β-hexosaminidase and histamine release, and suppressed NF-κB pathway. What's more, the degranulation of RBL-2H3 was reduced after Syk silence and increased after Syk overexpression.

CONCLUSION

Our findings clearly suggested that VYAC treat AD through inhibiting the inflammatory mediator productions and blocking mast cell degranulation via suppressing Syk mediated NF-κB pathway.

Dasatinib Inhibits Lyn and Fyn Src-Family Kinases in Mast Cells to Suppress Type I Hypersensitivity in Mice

Mast cells (MCs) are systemically distributed and secrete several allergic mediators such as histamine and leukotrienes to cause type I hypersensitivity. Dasatinib is a type of anti-cancer agent and it has also been reported to inhibit human basophils. However, dasatinib has not been reported for its inhibitory effects on MCs or type I hypersensitivity in mice. In this study, we examined the inhibitory effect of dasatinib on MCs and MC-mediated allergic response in vitro and in vivo. in vitro, dasatinib inhibited the degranulation of MCs by antigen stimulation in a dose-dependent manner (IC₅₀, ~34 nM for RBL-2H3 cells; ~52 nM for BMMCs) without any cytotoxicity. It also suppressed the secretion of inflammatory cytokines IL-4 and TNF-α by antigen stimulation. Furthermore, dasatinib inhibited MC-mediated passive cutaneous anaphylaxis (PCA) in mice (ED₅₀, ~29 mg/kg). Notably, dasatinib significantly suppressed the degranulation of MCs in the ear tissue. As the mechanism of its effect, dasatinib inhibited the activation of Syk and Syk-mediated downstream signaling proteins, LAT, PLCγ1, and three typical MAP kinases (Erk1/2, JNK, and p38), which are essential for the activation of MCs. Interestingly, in vitro tyrosine kinase assay, dasatinib directly inhibited the activities of Lyn and Fyn, the upstream tyrosine kinases of Syk in MCs. Taken together, dasatinib suppresses MCs and PCA in vitro and in vivo through the inhibition of Lyn and Fyn Src-family kinases. Therefore, we suggest the possibility of repositioning the anti-cancer drug dasatinib as a treatment for various MC-mediated type I hypersensitive diseases.

The antipsychotic drug pimozide inhibits IgE-mediated mast cell degranulation and migration

BACKGROUND

Mast cells (MCs) mediate a key role in allergic diseases. Detailed studies of how the neuroleptic drug pimozide affects MC activity are lacking. The aim of this study was to investigate pimozide inhibition of immunoglobulin E (IgE)-mediated MC activation and MC-mediated allergic responses.

METHOD

MCs were stimulated with anti-dinitrophenyl (DNP) IgE antibodies and DNP-horse serum albumin (HSA) antigen (Ag), and anti-allergic pimozide effects were detected by measuring β-hexosaminidase levels. Morphological changes were observed histologically. In vivo pimozide effects were assessed in passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-sensitized active systemic anaphylaxis mouse (ASA) model experiments. Levels of phosphorylated (p-) SYK (spleen tyrosine kinase) and MAPKs (mitogen-activated protein kinases) were detected in western blots.

RESULTS

We found that pimozide inhibited MC degranulation, reduced MC release of β-hexosaminidase dose-dependently in activated RBL-2H3 (IC₅₀: 13.52 μM) and bone marrow derived MC (BMMC) (IC₅₀: 42.42 μM), and reduced MC morphological changes. The IgE/Ag-induced migration effect was suppressed by pimozide treatment dose-dependently. Pimozide down-regulated IgE/Ag-induced phosphorylation of SYK and MAPKs in activated MCs. Moreover, pimozide attenuated allergic reactions in PCA and ASA model mice, and decreased MC populations among splenic cells.

CONCLUSIONS

The antipsychotic drug pimozide can suppress IgE-mediated MC activation in vitro and in vivo and should be considered for repurposing to suppress MC-mediated diseases.

CDK4/6 inhibitor palbociclib suppresses IgE-mediated mast cell activation

BACKGROUND

Mast cell activation causes degranulation and release of cytokines, thereby promoting inflammation. The aim of this study was to investigate the inhibitory effect of CDK4/6 inhibition on mast cell activation in vitro and in vivo.

METHODS

RBL-2H3 rat basophilic leukemia cells (BLCs) and mouse bone marrow-derived mast cells (BMMCs) were sensitized with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated with DNP-human serum albumin (HSA) antigens, and treated with the CDK4/6 inhibitor palbociclib. Histological stains were applied to reveal cytomorphological changes. Murine IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) models were used to examine palbociclib effects on allergic reactions in vivo. Western blots were performed to detect the expression of cell signaling molecules associated with mast cell activation.

RESULTS

Activated BLCs and BMMCs released copious granule-related mediators (histamine and β-hexosaminidase), which was reduced by palbociclib in a concentration-dependent manner. Palbociclib inhibited expression of the mast cell activation marker CD63 in activated BLCs and inhibited granule release (visualized with toluidine blue staining) while preventing morphological changes, (elongated shape maintained) and filamentous actin (F-actin) reorganization. Palbociclib suppressed molecular Lyn and/or mitogen-activated protein kinase (MAPK) signaling associated with mast cell activation in stimulated BLCs and attenuated allergic reactions in PCA mice dose dependently. Palbociclib attenuated body temperature reduction and diminished serum histamine levels in ovalbumin OVA-challenged ASA mice.

CONCLUSION

Palbociclib suppresses IgE-mediated mast cell activation in vitro and in vivo, suggesting that it may be developed into a therapy for mast cell-mediated allergic diseases via inhibition of mast cell degranulation.

Jacareubin inhibits FcεRI-induced extracellular calcium entry and production of reactive oxygen species required for anaphylactic degranulation of mast cells

Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC₅₀ = 46 nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.

Repositioning of anti-cancer drug candidate, AZD7762, to an anti-allergic drug suppressing IgE-mediated mast cells and allergic responses via the inhibition of Lyn and Fyn

Mast cells are critical effector cells in IgE-mediated allergic responses. The aim of this study was to investigate the anti-allergic effects of 3-[(aminocarbonyl)amino]-5-(3-fluorophenyl)-N-(3S)-3-piperidinyl-2-thiophenecarboxamide (AZD7762) in vitro and in vivo. AZD7762 inhibited the antigen-stimulated degranulation from RBL-2H3 (IC₅₀, ∼27.9 nM) and BMMCs (IC₅₀, ∼99.3 nM) in a dose-dependent manner. AZD7762 also inhibited the production of TNF-α and IL-4. As the mechanism of its action, AZD7762 inhibited the activation of Syk and its downstream signaling proteins, such as Linker of activated T cells (LAT), phospholipase (PL) Cγ1, Akt, and mitogen-activated protein (MAP) kinases (Erk1/2, p38, and JNK) in mast cells. In in vitro protein kinase assay, AZD7762 inhibited the activity of Lyn and Fyn kinases, which are important for the activation of Syk in mast cells. Furthermore, AZD7762 also suppressed the degranulation of LAD2 human mast cells (IC₅₀, ∼49.9 nM) and activation of Syk in a dose-dependent manner. As observed in experiments with mast cells in vitro, AZD7762 inhibited antigen-mediated passive cutaneous anaphylaxis in mice (ED₅₀, ∼35.8 mg/kg). Altogether, these results suggest that AZD7762 could be used as a new therapeutic agent for mast cell-mediated allergic diseases.

Anti-inflammatory activity of mulberrofuran K isolated from the bark of Morus bombycis

Morus bombycis Koidzumi, commonly known as silkworm mulberry, is a plant belonging to family Moraceae. It has been used in Asian countries as a traditional medicine for treating hypertension, diabetes, and inflammatory disorders. In this study, we isolated eleven compounds from the cortex of M. bombycis and evaluated their inhibitory effects on nitric oxide (NO) production as an indicator of their anti-inflammatory activities using lipopolysaccharide (LPS)-stimulated murine macrophages. Compound 4 showed the most potent inhibitory activity on NO production. It was identified as mulberrofuran K (MFK). Anti-inflammatory activity of MFK was then carried out using LPS-stimulated RAW264.7 cells. MFK suppressed the production of NO, reactive oxygen species (ROS), and proinflammatory cytokines (interleukin (IL)-1β, IL-6 and tumor necrosis factor alpha (TNF-α)) in a concentration-dependent manner. Western blot analysis revealed that MFK treatment inhibited expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). MFK also inhibited transcriptional activation of nuclear factor-κB (NF-κB) and extracellular-regulated kinases (ERK) 1/2 in LPS-stimulated murine macrophages. These results suggest that MFK, an anti-inflammatory constituents of M. bombycis cortex, has potential as a therapeutic candidates for preventing and treating inflammatory diseases.

Anti-inflammatory properties of Morus bombycis Koidzumi via inhibiting IFN-β signaling and NLRP3 inflammasome activation

ETHNOPHARMACOLOGICAL RELEVANCE

Morus bombycis Koidzumi (M. bombycis, Moraceae) has been used in Asian countries as a traditional medicine for the treatment of hypertension, diabetes, and inflammation-related disorders.

AIM OF STUDY

Although its anti-inflammatory actions have been partly documented, scientific evidence involving its molecular mechanisms related to inflammasome activation signaling pathways remains unknown.

MATERIALS AND METHODS

Lipopolysaccharide-stimulated RAW 264.7 cells and bone marrow-derived murine macrophages were used to study the in vitro effect of methanolic extract of M. bombycis (MB) on inflammatory responses. A monosodium urate crystal (MSU)-induced peritonitis murine model was used to study the in vivo effects.

RESULTS

MB attenuated the production of nitric oxide and interleukin-6, through the regulation of the interferon-β receptor signaling pathway. MB also inhibited IL-1β secretion via attenuation of NLRP3 inflammasome activation. Furthermore, MB inhibited MSU-induced peritonitis in the in vivo murine model.

CONCLUSIONS

This study provides the key molecular mechanisms involved in the anti-inflammatory effects of M. bombycis, substantiating the traditional claims of its use in the treatment of inflammation-related disorders.