Polydatin (PD) inhibits IgE-mediated passive cutaneous anaphylaxis in mice by stabilizing mast cells through modulating Ca²⁺ mobilization

Polydatin: Pharmacological Mechanisms, Therapeutic Targets, Biological Activities, and Health Benefits

Polydatin is a natural potent stilbenoid polyphenol and a resveratrol derivative with improved bioavailability. Polydatin possesses potential biological activities predominantly through the modulation of pivotal signaling pathways involved in inflammation, oxidative stress, and apoptosis. Various imperative biological activities have been suggested for polydatin towards promising therapeutic effects, including anticancer, cardioprotective, anti-diabetic, gastroprotective, hepatoprotective, neuroprotective, anti-microbial, as well as health-promoting roles on the renal system, the respiratory system, rheumatoid diseases, the skeletal system, and women's health. In the present study, the therapeutic targets, biological activities, pharmacological mechanisms, and health benefits of polydatin are reviewed to provide new insights to researchers. The need to develop further clinical trials and novel delivery systems of polydatin is also considered to reveal new insights to researchers.

Control over Polymorph Formation of Polydatin in Binary Solvent System and Structural Characterization

Polydatin is a natural product used for anti-oxidant, anti-inflammatory and anti-tumor purposes, and often added in medicine, nutraceutical, cosmetics, and dietary supplement. Polymorphism is a key feature of solid-state pharmaceutical products. Polymorphic modifications may exhibit different physical and chemical properties. Here we report two different polymorphs, and the amorphous form of Polydatin. Polymorphs were prepared in binary solvent system. The crystal structures of the two forms were revealed for the first time. The structure and 3D packing were determined with single crystal X-ray diffraction analysis. The batch consistency and stability were identified with Powder X-ray diffraction analysis. Various functional groups present in the polymorphs were analyzed with fourier transform infrared spectroscopic method. The thermal properties were investigated with DSC and TGA. HPLC-MS was used for the pharmacokinetic study. Results show that form B has the faster absorption, and can be maintained in animal bodies for a longer time than form A.

Magnolin inhibits IgE/Ag-induced allergy in vivo and in vitro

Mast cells (MCs) play critical roles in allergic reactions and modulating the activation of MCs could be an effective strategy to treat allergic diseases, which cause a rapidly increasing threat to the public health. Herein, we described that Magnolin, a major component from Flos magnoliae could inhibit IgE-dependent MCs activation. We found Magnolin inhibited IgE/Ag-induced calcium mobilization, degranulation, and cytokines release in LAD2 cells. Magnolin was also found to attenuate IgE/Ag-induced mice paw swelling in a dose-dependent manner. Further mechanistic studies suggested a possible anti-allergic and anti-inflammatory effects of Magnolin in IgE/Ag-induced anaphylactic reactions. Thereby, Magnolin could be a potential therapeutic agent for preventing mast cell-related immediate and delayed allergic diseases.

The Role of Mast Cells in Stroke

Mast cells (MCs) are densely granulated perivascular resident cells of hematopoietic origin. Through the release of preformed mediators stored in their granules and newly synthesized molecules, they are able to initiate, modulate, and prolong the immune response upon activation. Their presence in the central nervous system (CNS) has been documented for more than a century. Over the years, MCs have been associated with various neuroinflammatory conditions of CNS, including stroke. They can exacerbate CNS damage in models of ischemic and hemorrhagic stroke by amplifying the inflammatory responses and promoting brain–blood barrier disruption, brain edema, extravasation, and hemorrhage. Here, we review the role of these peculiar cells in the pathophysiology of stroke, in both immature and adult brain. Further, we discuss the role of MCs as potential targets for the treatment of stroke and the compounds potentially active as MCs modulators.

Adjuvanted Immunotherapy Approaches for Peanut Allergy

Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.

Polydatin inhibits mast cell-mediated allergic inflammation by targeting PI3K/Akt, MAPK, NF-κB and Nrf2/HO-1 pathways

Polydatin(PD) shows anti-allergic inflammatory effect, and this study investigated its underlying mechanisms in in vitro and in vivo models. IgE-mediated passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA) models were used to confirm PD effect in vivo. Various signaling pathway proteins in mast cell were examined. RT-PCR, ELISA and western blotting were applied when appropriate. Activity of Lyn and Fyn kinases in vitro was measured using the Kinase Enzyme System. PD dose-dependently reduced the pigmentation of Evans blue in the PCA model and decreased the concentration of serum histamine in PSA model, and attenuated the degranulation of mast cells without generating cytotoxicity. PD decreased pro-inflammatory cytokine expression (TNF-α, IL-4, IL-1β, and IL-8). PD directly inhibited activity of Lyn and Syk kinases and down-regulated downstream signaling pathway including MAPK, PI3K/AKT and NF-kB. In addition, PD also targets Nrf2/HO-1 pathway to inhibit mast cell-derived allergic inflammatory reactions. In conclusion, the study demonstrates that PD is a possible therapeutic candidate for allergic inflammatory diseases. It directly inhibited activity of Lyn and Syk kinases and down-regulates the signaling pathway of MAPK, PI3K/AKT and NF-κB, and up-regulates the signaling pathway of Nrf2/HO-1 to inhibit the degranulation of mast cells.

Polydatin Induces Apoptosis and Inhibits Growth of Acute Monocytic Leukemia Cells

Polydatin (PD), a component isolated from Polygonum cuspidatum, has various activities such as inhibiting platelet aggregation, lowering level of blood lipid, reducing lipid peroxidation, and so on. However, the antitumor activity of PD has been poorly reported. In the present study, effect of PD on cell proliferation was evaluated by Cell Counting Kit-8, and cell cycle and apoptosis were investigated by flow cytometry. Meanwhile, the protein expression level of Bc1-2, Bax, cyclin A, cyclin B, and cyclin D1, which associated with apoptosis and cell cycle were analyzed by Western blotting. Results show that PD could effectively inhibit the growth, arrest cells in S phase, and induce apoptosis of acute monocytic leukemia cell line THP-1; meanwhile, expression of cyclin D1 and Bc1-2 decreased significantly, and expression of Bax and cyclin A increased notably. All results suggest that PD maybe a potential therapeutic strategy for acute monocytic leukemia.

The Immunoregulatory Effects of Traditional Chinese Medicine on Treatment of Asthma or Asthmatic Inflammation

Asthma is a chronic respiratory symptoms with variable airflow limitation and airway hyperresponsiveness (AHR), and causes high economic burden. Traditional Chinese medicine (TCM) has a long-lasting history of using herbal medicine in the treatment of various respiratory diseases including asthma. In the last several decades, an increasing number of herbs have been shown to be effective in the treatment of asthma in clinical trials or asthmatic inflammation in animal models. Literature about the effects of TCM on the immune system were searched in electronic databases such as PubMed, Google Scholar and Scopus from 2000 to 2014. 'TCM' and 'asthma' were used as keywords for the searches. Over 400 literatures were searched and the literatures about the immune system were selected and reviewed. We only reviewed literatures published in English. Accumulating evidence suggests that TCM can directly inhibit the activation and migration of inflammatory cells, regulate the balance of Th1/Th2 responses, and suppress allergic hyperreactivity through inducing regulatory T cells or attenuating the function of dendritic cells (DCs). These studies provided useful information to facilitate the use of TCM to treat asthma. This review was conducted to classify the findings based on their possible mechanisms of action reported.

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.

Twenty-first century mast cell stabilizers

Mast cell stabilizing drugs inhibit the release of allergic mediators from mast cells and are used clinically to prevent allergic reactions to common allergens. Despite the relative success of the most commonly prescribed mast cell stabilizer, disodium cromoglycate, in use for the preventative treatment of bronchial asthma, allergic conjunctivitis and vernal keratoconjunctivitis, there still remains an urgent need to design new substances that are less expensive and require less frequent dosing schedules. In this regard, recent developments towards the discovery of the next generation of mast cell stabilizing drugs has included studies on substances isolated from natural sources, biological, newly synthesized compounds and drugs licensed for other indications. The diversity of natural products evaluated range from simple phenols, alkaloids, terpenes to simple amino acids. While in some cases their precise mode of action remains unknown it has nevertheless sparked interest in the development of synthetic derivatives with improved pharmacological properties. Within the purely synthetic class of inhibitors, particular attention has been devoted to the inhibition of important signalling molecules including spleen TK and JAK3. The statin class of cholesterol-lowering drugs as well as nilotinib, a TK inhibitor, are just some examples of clinically used drugs that have been evaluated for their anti-allergic properties. Here, we examine each approach under investigation, summarize the test data generated and offer suggestions for further preclinical evaluation before their therapeutic potential can be realized.

Resveratrol and calcium signaling: molecular mechanisms and clinical relevance

Resveratrol is a naturally occurring compound contributing to cellular defense mechanisms in plants. Its use as a nutritional component and/or supplement in a number of diseases, disorders, and syndromes such as chronic diseases of the central nervous system, cancer, inflammatory diseases, diabetes, and cardiovascular diseases has prompted great interest in the underlying molecular mechanisms of action. The present review focuses on resveratrol, specifically its isomer trans-resveratrol, and its effects on intracellular calcium signaling mechanisms. As resveratrol's mechanisms of action are likely pleiotropic, its effects and interactions with key signaling proteins controlling cellular calcium homeostasis are reviewed and discussed. The clinical relevance of resveratrol's actions on excitable cells, transformed or cancer cells, immune cells and retinal pigment epithelial cells are contrasted with a review of the molecular mechanisms affecting calcium signaling proteins on the plasma membrane, cytoplasm, endoplasmic reticulum, and mitochondria. The present review emphasizes the correlation between molecular mechanisms of action that have recently been identified for resveratrol and their clinical implications.

Polydatin: a review of pharmacology and pharmacokinetics

CONTEXT

Polydatin, also named piceid (3,4',5-trihydroxystilbene-3-β-d-glucoside, PD), is a monocrystalline compound isolated from Polygonum cuspidatum Sieb. et Zucc. (Polygonaceae), but is also detected in grape, peanut, hop cones, red wines, hop pellets, cocoa-containing products, chocolate products and many daily diets. There are numerous investigations reported of PD in the past 22 years, but they are usually scattered across various publications, which may block further research and clinical use of PD.

OBJECTIVE

The article summarizes and evaluates the published scientific information of PD pharmacological effects and pharmacokinetics since 1990.

MATERIALS AND METHODS

The information from 98 cases included in this review was compiled using major databases such as MEDLINE, Elsevier, Springer, PubMed, Scholar and CNKI.

RESULTS

Numerous pharmacological investigations of PD mainly focus on cardiovascular effects, neuroprotection, anti-inflammatory and immunoregulatory effects, anti-oxidation, anti-tumor, liver and lung protection, etc.

CONCLUSION

A great number of pharmacological and pharmacokinetic investigations in the past 22 years have demonstrated that PD has favorable therapeutic properties, indicating its potential as an effective material. However, further research is needed to explore its molecular mechanisms of action and definitive target proteins.

Polydatin attenuated food allergy via store-operated calcium channels in mast cell

AIM: To investigate the effect of polydatin (PD), a resveratrol glucoside, on mast cell degranulation and anti-allergic activity.

METHODS: After the rats were orally sensitized with ovalbumin (OVA) for 48 d and underwent PD treatment for 4 d, all the rats were stimulated by 100 mg/mL OVA for 24 h and then sacrificed for the following experiments. The small intestines from all the groups were prepared for morphology examination by hematoxylin and eosin staining. We also used a smooth muscle organ bath to evaluate the motility of the small intestines. The OVA-specific immunoglobulin E (IgE) production and interleukin-4 (IL-4) levels in serum or supernatant of intestinal mucosa homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA). Using toluidine blue stain, the activation and degranulation of isolated rat peritoneal mast cells (RPMCs) were analyzed. Release of histamine from RPMCs was measured by ELISA, and regulation of PD on intracellular Ca²⁺ mobilization was investigated by probing intracellular Ca²⁺ with fluo-4 fluorescent dye, with the signal recorded and analyzed.

RESULTS: We found that intragastric treatment with PD significantly reduced loss of mucosal barrier integrity in the small intestine. However, OVA-sensitization caused significant hyperactivity in the small intestine of allergic rats, which was attenuated by PD administration by 42% (1.26 ± 0.13 g vs OVA 2.18 ± 0.21 g, P < 0.01). PD therapy also inhibited IgE production (3.95 ± 0.53 ng/mL vs OVA 4.53 ± 0.52 ng/mL, P < 0.05) by suppressing the secretion of Th2-type cytokine, IL-4, by 34% (38.58 ± 4.41 pg/mL vs OVA 58.15 ± 6.24 pg/mL, P < 0.01). The ratio of degranulated mast cells, as indicated by vehicles (at least five) around the cells, dramatically increased in the OVA group by 5.5 fold (63.50% ± 15.51% vs phosphate-buffered saline 11.15% ± 8.26%, P < 0.001) and fell by 65% after PD treatment (21.95% ± 4.37% vs OVA 63.50% ± 15.51%, P < 0.001). PD mediated attenuation of mast cell degranulation was further confirmed by decreased histamine levels in both serum (5.98 ± 0.17 vs OVA 6.67 ± 0.12, P < 0.05) and intestinal mucosa homogenates (5.83 ± 0.91 vs OVA 7.35 ± 0.97, P < 0.05). Furthermore, we demonstrated that administration with PD significantly decreased mast cell degranulation due to reduced Ca²⁺ influx through store-operated calcium channels (SOCs) (2.35 ± 0.39 vs OVA 3.51 ± 0.38, P < 0.01).

CONCLUSION: Taken together, our data indicate that PD stabilizes mast cells by suppressing intracellular Ca²⁺ mobilization, mainly through inhibiting Ca²⁺ entry via SOCs, thus exerting a protective role against OVA-sensitized food allergy.