Homoisoflavanone prevents mast cell activation and allergic responses by inhibition of Syk signaling pathway

Bioactive Polysaccharides From Cremastra Appendiculata Attenuate Lipid Accumulation In Vitro Model of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic disease with a rapidly growing incidence worldwide, presenting as an ever-increasing burden to the healthcare system. In this study, we explored that Cremastra appendiculata, a valuable traditional medicine in China, could alleviate lipid accumulation in HepG2 cells. C. appendiculata polysaccharide (CAP) was extracted from the pseudobulbs of C. appendiculata and oligosaccharide (oligoCAP) was obtained by enzymatical digestion of the CAP with endo-β-mannanase. Molecular weight of CAP and oligoCAP was determined to be 46 415 and 933 Da. Oleic acid (OA) induced steatosis in HepG2 cells was adopted as an in vitro NAFLD model. CAP and oligoCAP could reduce the OA-induced lipid accumulation and significantly reduce the total cholesterol and triglyceride content in the HepG2 cells. CAP and oligoCAP possessed lipid-lowering and anti-inflammatory activities especially by enhancing lipolysis and suppressing lipid synthesis shown by quantitative polymerase chain reaction results. Transcriptome analysis showed that CAP and oligoCAP mainly played anti-NAFLD roles in the pathways of lipid metabolism and necroptosis. Moreover, in vivo biodistribution results showed that both CAP and oligoCAP were mostly distributed in the small intestine and stomach tissues 24 h after administration, which may be related to the structural and molecular weight characterization of the polysaccharides.

Anemoside B4 protects against IgE-dependent allergic responses by suppressing the PLC/IP3 and JAK/STAT3 pathways

Anemoside B4 (AB4) is a natural triterpenoid abundant in the roots of Pulsatilla chinensis. Although various biological activities have been widely attributed to AB4, few studies have focused on its antiallergic effects. In this study the inhibitory effects of AB4 on immunoglobulin E (IgE)-mediated allergic responses were investigated, both in vitro and in vivo, and the mechanism of its effects. IgE-mediated passive cutaneous anaphylaxis was used to elucidate the antiallergic effects of AB4 in vivo. The degranulation assay, calcium imaging, and cytokine and chemokine release in the laboratory of allergic disease 2 (LAD2) cell line were used to evaluate the antiallergic effect of AB4 in vitro. Pathological staining was performed to analyze angiectasis. Western blot analysis was performed to investigate the downstream signaling pathways. AB4 dose-dependently attenuated ovalbumin/IgE-induced paw swelling in mice, and reduced the serum concentrations of tumor necrosis factor-alpha and C-C motif chemokine 2. In addition, AB4 suppressed IgE-mediated LAD2 cell degranulation, calcium influx, and PLC/IP3 and JAK/STAT3 phosphorylation. Our results suggest that AB4 inhibits allergic reactions through the PLC/IP3 and JAK/STAT3 pathways.

MicroRNA 27b-3p Modulates SYK in Pediatric Asthma Induced by Dust Mites

The PI3K-AKT pathway is known to regulate cytokines in dust mite-induced pediatric asthma. However, the underlying molecular steps involved are not clear. In order to clarify further the molecular steps, this study investigated the expression of certain genes and the involvement of miRNAs in the PI3K-AKT pathway, which might affect the resultant cytokine-secretion. in-vivo and in-vitro ELISA, qRT-PCR and microarrays analyses were used in this study. A down-expression of miRNA-27b-3p in dust mite induced asthma group (group D) was found by microarray analysis. This was confirmed by qRT-PCR that found the miRNA-27b-3p transcripts that regulated the expression of SYK and EGFR were also significantly decreased (p < 0.01) in group D. The transcript levels of the SYK and PI3K genes were higher, while those of EGFR were lower in the former group. Meanwhile, we found significant differences in plasma concentrations of some cytokines between the dust mite-induced asthma subjects and the healthy controls. On the other hand, this correlated with the finding that the transcripts of SYK and its downstream PI3K were decreased in HBE transfected with miRNA-27b-3p, but were increased in HBE transfected with the inhibitor in vitro. Our results indicate that the differential expression of the miRNAs in dust mite-induced pediatric asthma may regulate their target gene SYK and may have an impact on the PI3K-AKT pathway associated with the production of cytokines. These findings should add new insight into the pathogenesis of pediatric asthma.

Cirsium maritimum Makino Inhibits the Antigen/Immunoglobulin-E-Mediated Allergic Response In Vitro and In Vivo

We investigated whether Cirsium maritimum Makino can inhibit immunoglobulin-E-mediated allergic response in rat basophilic leukemia (RBL-2H3) cells and passive cutaneous anaphylaxis (PCA) in BALB/c mice. In vitro, the ethyl acetate extract of C. maritimum Makino (ECMM) significantly inhibited β-hexosaminidase release and decreased intracellular Ca²⁺ levels in RBL-2H3 cells. Moreover, ECMM leaves more strongly suppressed the release of β-hexosaminidase than ECMM flowers. ECMM leaves also significantly suppressed the PCA reaction in the murine model. High-performance liquid chromatography and ¹H and ¹³C nuclear magnetic resonance indicated that cirsimaritin, a flavonoid, was concentrated in active fractions of the extract. Our findings suggest that ECMM leaves have a potential regulatory effect on allergic reactions that may be mediated by mast cells. Furthermore, cirsimaritin may be the active anti-allergic component in C. maritimum Makino.

Dysivillosins A-D, Unusual Anti-allergic Meroterpenoids from the Marine Sponge Dysidea villosa

Four unusual meroterpenoids, dysivillosins A–D (1–4), were isolated from an organic extract of the marine sponge Dysidea villosa collected from the South China Sea. Their planar structures were determined by 1D and 2D NMR and HRESIMS techniques, while the relative and absolute configurations were elucidated by NOESY experiments and comparison between the calculated and experimental ECD spectra. To the best of our knowledge, dysivillosins A–D are the first examples of terpene-polyketide-pyridine hybrid metabolites from the nature. Anti-allergic activity evaluation showed that compounds 1–4 potently inhibited the release of β-hexosaminidase, a marker of degranulation, in a dose-dependent manner with IC₅₀ values of 8.2–19.9 μM. Additionally, the four meroterpenoids could downregulate the production of lipid mediator leukotrienes B₄ (LTB₄) and pro-inflammatory cytokine interleukin-4 (IL-4) in the antigen-stimulated RBL-2H3 mast cells. Further biological investigations revealed that dysivillosin A (1) could suppress the phosphorylation of Syk and PLCγ1 in IgE/FcɛRI/Syk signaling pathway, which resulted in the inhibition of degranulation and the downregulation of LTB₄ and IL-4 production in mast cells.

A new prenylated flavone from Pleione bulbocodioides

A new prenylated flavone, 3,5,7,3'-tetrahydroxy-8,4'-dimethoxy-6-(3-methylbut-2- enyl)flavone (1), together with three known flavone derivatives (2-4), two known dihydrophenanthrenes (5-6), two known lignin derivatives (7-8), and three known phenolic glycoside compounds (9-11) were isolated from the n-BuOH extract of Pleione bulbocodioides. High-resolution electrospray ionization mass spectroscopy (HRESIMS), FTIR spectroscopy, and NMR techniques were used to elucidate the structures of these compounds. Biological investigations showed that compound 5, 4,7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene, exhibited potent anti-inflammatory activity on LPS-stimulated NO production in BV-2 microglial cells, with IC₅₀ value of 5.44 μM.

Design, synthesis and biological evaluation of photoaffinity probes of antiangiogenic homoisoflavonoids

A naturally occurring homoisoflavonoid, cremastranone (1) inhibited angiogenesis in vitro and in vivo. We developed an analogue SH-11037 (2) which is more potent than cremastranone in human retinal microvascular endothelial cells (HRECs) and blocks neovascularization in animal models. Despite their efficacy, the mechanism of these compounds is not yet fully known. In the course of building on a strong foundation of SAR and creating a novel chemical tool for target identification of homoisoflavonoid-binding proteins, various types of photoaffinity probes were designed and synthesized in which benzophenone and biotin were attached to homoisoflavanonoids using PEG linkers on either the C-3' or C-7 position. Notably, the photoaffinity probes linking on the phenol group of the C-3' position retain excellent activity of inhibiting retinal endothelial cell proliferation with up to 72nM of GI50.

Extracellular superoxide dismutase ameliorates house dust mite-induced atopic dermatitis-like skin inflammation and inhibits mast cell activation in mice

Extracellular superoxide dismutase (EC-SOD) is an enzyme that catalyses the dismutation of superoxide anions. It has multiple functions, such as reactive oxygen species scavenging, anti-angiogenic, anti-inflammatory, antichemotatic and antitumor activities. Recently, we demonstrated that EC-SOD inhibits ovalbumin-induced allergic airway inflammation in mice. However, the anti-allergic effect of EC-SOD on skin tissue and the role of EC-SOD in mast cells, which are important for allergic responses, have not been well studied. In this study, we investigated whether EC-SOD can alleviate atopic dermatitis in mice and inhibit mast cell activation. Treatment with human recombinant EC-SOD ameliorated house dust mite-induced atopic dermatitis in mice. Furthermore, the levels of pro-allergic cytokine gene expression and histamine release increased in EC-SOD KO mast cells and decreased in EC-SOD overexpressing mast cells, suggesting that EC-SOD inhibits mast cell activation. Consistently, a passive cutaneous anaphylaxis experiment showed more blood leakage from EC-SOD KO mouse ear skin, implying that the lack of EC-SOD increases allergic responses. These results suggest that EC-SOD inhibits mast cell activation and atopic dermatitis and that the loss of EC-SOD causes more severe allergic responses, implying that EC-SOD might be a good drug candidate for treatment of allergic disorders, such as atopic dermatitis.

Genus: Calanthe to Cyrtosia

This large chapter describe the herbal usage and pharmacology of 73 species in 12 genera (Calanthe, Callostylis, Cephalanthera, Cleisostoma, Coelogyne, Conchidium, Corymborkhis, Cremastra, Crepidium, Cymbidium, Cypripedium and Cyrtosia). A good percentage of the orchids are commonly cultivated as ornamental plants and many hybrids have been produced with Calanthe and Cymbidium. TCM makes use of 14 species of Calanthe and Rumphius who authored Hut Amboinesche Kruidboek [the Amboinese Herbal, Volumes 1–6 (1741–1750), published posthumously] described Calanthe triplicata. Calanthe species contain compounds with antitumour and hair-restoring properties. Fourteen species of Coelogyne are medicinal and several have been studied phytochemically by Majumder’s group in Calcutta. Another large group, Cymbidium, with 17 medicinal species, is also much studied. Lectins present in some species suppress replication of coronaviruses, toroviruses and viruses. An interesting compound that suppresses angiogenesis has been discovered in Cremastra appendiculata and it may find a role in preventing blindness and spread of cancers. Cyrtosia is a homomycotrophic genus and should be an interesting subject for phytochemical studies.

Sinomenine potentiates P815 cell degranulation via upregulation of Ca2+ mobilization through the Lyn/PLCγ/IP3R pathway

Mast cells are vital mediators of drug allergy and, therefore, studying the relationship between drug allergy and mast cells is essential. Sinomenine is the principal active component of Sinomenium acutum, which has anti-inflammatory and anti-immune effects, and is used to treat various rheumatoid diseases. However, allergic responses to sinomenine are frequently reported. Therefore, this study assessed the effects of sinomenine on mast cell activation to characterize its allergic effects and the underlying mechanisms. Enzyme-linked immunosorbent assay (ELISA), western blot analyses, and degranulation assays were performed to measure pro-inflammatory and allergic mediators in P815 cells. The allergenic effects of sinomenine were also determined in mice by using active general anaphylaxis (ASA). The results indicated that sinomenine induced inositol-1,4,5-trisphosphate (IP₃) production and the release of histamine, interleukin (IL)-6, and endoplasmic reticulum Ca²⁺ in P815 cells. Furthermore, sinomenine upregulated the phosphorylation of sarcoma (Src), phospholipase C (PLC)-γ1, and IP₃ receptor (R). Therefore, sinomenine induced concentration-dependent mast cell activation directly in vitro Furthermore, our in vivo data identified an appropriate intravenous dose that did not induce these allergic effects, thereby providing information for the potential safe clinical use of sinomenine.

Dietary Compound Kaempferol Inhibits Airway Thickening Induced by Allergic Reaction in a Bovine Serum Albumin-Induced Model of Asthma

Asthma is characterized by aberrant airways including epithelial thickening, goblet cell hyperplasia, and smooth muscle hypertrophy within the airway wall. The current study examined whether kaempferol inhibited mast cell degranulation and prostaglandin (PG) release leading to the development of aberrant airways, using an in vitro model of dinitrophenylated bovine serum albumin (DNP-BSA)-sensitized rat basophilic leukemia (RBL-2H3) mast cells and an in vivo model of BSA-challenged asthmatic mice. Nontoxic kaempferol at 10-20 μM suppressed β-hexosaminidase release and cyclooxygenase 2 (COX2)-mediated production of prostaglandin D2 (PGD2) and prostaglandin F2α (PGF2α) in sensitized mast cells. Oral administration of ≤20 mg/kg kaempferol blocked bovine serum albumin (BSA) inhalation-induced epithelial cell excrescence and smooth muscle hypertrophy by attenuating the induction of COX2 and the formation of PGD2 and PGF2α, together with reducing the anti-α-smooth muscle actin (α-SMA) expression in mouse airways. Kaempferol deterred the antigen-induced mast cell activation of cytosolic phospholipase A2 (cPLA2) responsive to protein kinase Cμ (PKCμ) and extracellular signal-regulated kinase (ERK). Furthermore, the antigen-challenged activation of Syk-phospholipase Cγ (PLCγ) pathway was dampened in kaempferol-supplemented mast cells. These results demonstrated that kaempferol inhibited airway wall thickening through disturbing Syk-PLCγ signaling and PKCμ-ERK-cPLA2-COX2 signaling in antigen-exposed mast cells. Thus, kaempferol may be a potent anti-allergic compound targeting allergic asthma typical of airway hyperplasia and hypertrophy.

Mast cell stabilisers

Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated.

Synthesis and Biological Evaluation of Novel Homoisoflavonoids for Retinal Neovascularization

Eye diseases characterized by excessive angiogenesis such as wet age-related macular degeneration, proliferative diabetic retinopathy, and retinopathy of prematurity are major causes of blindness. Cremastranone is an antiangiogenic, naturally occurring homoisoflavanone with efficacy in retinal and choroidal neovascularization models and antiproliferative selectivity for endothelial cells over other cell types. We undertook a cell-based structure-activity relationship study to develop more potent cremastranone analogues, with improved antiproliferative selectivity for retinal endothelial cells. Phenylalanyl-incorporated homoisoflavonoids showed improved activity and remarkable selectivity for retinal microvascular endothelial cells. A lead compound inhibited angiogenesis in vitro without inducing apoptosis and had efficacy in the oxygen-induced retinopathy model in vivo.

Capsiate Inhibits DNFB-Induced Atopic Dermatitis in NC/Nga Mice through Mast Cell and CD4+ T-Cell Inactivation

Capsaicin has many biological effects, such as antioxidant, anticancer, and antiangiogenic effects, but it is rarely used because of its high pungency. Capsiate, a nonpungent capsaicin analog, also has multiple biological effects, similar to those of capsaicin, but does not cause irritation. However, the effect of capsiate on allergic responses and immune cells has not been well studied. In this study, we investigated the effect of capsiate on atopic dermatitis, mouse CD4+ T cells, and mast cell activation. Capsiate inhibited DNFB-induced atopic dermatitis in NC/Nga mice. Topical treatment with capsiate suppressed serum IgE levels and cytokine and chemokine expression in the skin of DNFB-treated NC/Nga mice. In addition, it suppressed the activation of CD4+ T cells and mast cells, which are implicated in allergic diseases. Capsiate inhibited the differentiation of naïve CD4+ T cells into T helper type 1 (Th1), Th2, and Th17 cells. Treatment with capsiate inhibited the expression of pro-inflammatory cytokines and degranulation from activated bone marrow-derived mast cells through the inhibition of extracellular signal-regulated kinase signal pathways. Consistent with these results, treatment with capsiate inhibited passive cutaneous anaphylaxis. Taken together, our results suggest that capsiate might be a good candidate molecule for the treatment of allergic diseases such as atopic dermatitis.

The first synthesis of the antiangiogenic homoisoflavanone, cremastranone

An antiangiogenic homoisoflavanone, cremastranone, was synthesized for the first time. This scalable synthesis, which includes selective demethylation, could be used to develop lead molecules to treat angiogenesis-induced eye diseases. Synthetic cremastranone inhibited the proliferation, migration and tube formation ability of human retinal microvascular endothelial cells, important steps in pathological angiogenesis.