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.

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Oxidative stress plays critical roles in airway inflammation that is usually accompanied by increased vascular permeability and plasma exudation. VEGF increases vascular permeability and leads to airway inflammation. In addition, VEGF has been shown to enhance receptor activator of NF-κB (RANK) expression in endothelial cells. An aim of the study was to determine the potential role of antioxidant in the regulation of RANK expression in murine model of asthma. We have used a C57BL/6 mouse model of allergic asthma to evaluate the effect of L-2-oxothiazolidine-4-carboxylic acid (OTC), a prodrug of cysteine, which acts as an antioxidant, and VEGF receptor inhibitor on RANK mRNA expression. The mice develop the following pathophysiological features of asthma in the lungs: increased expression of RANK mRNA, increased number of inflammatory cells of the airways, increased vascular permeability, and increased levels of VEGF. Administration of OTC and VEGF receptor inhibitor markedly reduced plasma extravasation and VEGF levels in allergen-induced asthmatic lungs. We also showed that the increased RANK mRNA expression at 72 h after ovalbumin inhalation were reduced by the administration of OTC or VEGF receptor inhibitor. The results indicate that OTC and VEGF receptor inhibitor which inhibit up-regulation of VEGF expression modulate RANK expression that may be in association with the regulation of vascular permeability, and suggest that VEGF may regulate the RANK expression. These findings provide a crucial molecular mechanism for the potential use of antioxidants to prevent and/or treat asthma and other airway inflammatory disorders.

This study is to investigate the effects of imperatorin (IMP) on allergic responses mediated by mast cells, both in vitro and in vivo. Passive cutaneous anaphylaxis (PCA) model was established. Histological detection was performed to assess the ear histology. ELISA and Western blot analysis were used to detect the levels of corresponding cytokines and signalling pathway proteins. IMP decreased the leakage of Evans blue and the ear thickness in the PCA models, in a dose-dependent manner, and alleviated the degranulation of mast cells. Moreover, IMP reduced the expression of TNF-α, IL-4, IL-1β, IL-8, and IL-13. Furthermore, IMP inhibited the phosphorylation levels of Syk, Lyn, PLC-γ1, and Gab2, as well as the downstream MAPK, PI3K/AKT, and NF-κB signaling pathways. In addition, IMP inhibited the mast cell-mediated allergic responses through the Nrf2/HO-1 pathway. IMP attenuates the allergic responses through inhibiting the degranulation and decreasing the expression levels of proinflammatory cytokines in the mast cells, involving the PI3K/Akt, MAPK, NF-κB, and Nrf2/HO-1 pathways.

Introduction Pterostilbene (Pts) may be used for allergic asthma treatment. The AMPK/Sirt1 and Nrf2/HO‐1 pathways are potential targets for asthma treatement. However, the relationship between Pts and AMPK/Sirt1 and Nrf2/HO‐1 pathways in asthma is unclear. Herein, we aim to explore the pharmacological effects of Pts on oxidative stress and allergic inflammatory response as well as the mechanism involving AMPK/Sirt1 and Nrf2/HO‐1 pathways. Methods Asthma model was established in mice with ovalbumin (OVA). The model mice were treated by different concentrations of Pts. Lung pathological changes were observed through histological staining. In vitro, lipopolysaccharide (LPS)‐stimulated 16HBE cells were treated with Pts. The siAMPKα2, siSirt1 and siNrf2 knockdown, and treatment with compound C, EX‐527 or ML385 were also performed in 16HBE cells. Enzyme‐linked immunosorbent assay was used to detect interleukin‐4 (IL‐4), IL‐13, IL‐5, total and OVA specific immunoglobulin E (IgE), and interferon γ (IFN‐γ). Pneumonography was used to measure the airway hyperreactivity (AHR). Superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels were also detected. Immunohistochemistry, Western blot and immunofluorescence were used to measure protein levels. Results Pts significantly attenuated lung inflammatory cell infiltration and goblet cell proliferation. Meanwhile, Pts treatment could reduce IL‐4, IL‐13, IL‐5, and IgE (total and OVA specific) levels in the asthma model mice. However, IFN‐γ in bronchoalveolar lavage fluid was elevated. In addition, Pts reduced AHR. We also found that Pts treatment promoted serum SOD and CAT, and reduced MDA. In vitro results showed that Pts treatment promoted iNOS, TNF‐α, COX‐2, IL‐1β, and IL‐6 expressions in 16HBE cells, prolonged G0/G1 phase of the cell cycle, and resulted in a shortened G2M phase. Moreover, we found that Pts promoted the phosphorylation of AMPK in 16HBE, and meanwhile inhibited the increase of ROS induced by LPS. Additionally, Pts treatment inhibited p‐AMPK, Sirt1, Nrf2 and HO‐1, which in turn leads to the alleviation of AMPK/Sirt1 and Nrf2/HO‐1 pathways. Conclusion Pts alleviated oxidative stress and allergic airway inflammation via regulation of AMPK/Sirt1and Nrf2/HO‐1 signaling pathways.