Inhibitory Effect ofLoranthus parasiticuson IgE-Mediated Allergic Responses in RBL-2H3 Cells

Abstract

The mistletoe Loranthus parasiticus has been used as a compound for traditional medicine in Northeast Asia for a long time and is known to possess neuroprotective action. Nonetheless, the effect of Loranthus parasiticus on allergic responses remains unknown. In the present study, we evaluated whether the water extract of Loranthus parasiticus (LPE) could inhibit IgE-mediated allergic responses in RBL-2H3 cells. LPE inhibited the release of β-hexosaminidase (IC50, 184.5 μg/mL) and the formation of tumor necrosis factor-α (IC50, 84.27 μg/mL), interleukin-4 (IC50, 93.43 μg/mL), prostaglandin E2 (IC50, 84.10 μg/mL), prostaglandin D2, and leukotriene C4 (IC50, 43.27 μg/mL) in a concentration-dependent manner. Moreover, LPE inhibited phosphorylation of Syk, PLCγ1/2, PKCδ, ERK, JNK, p38, and Akt. In the late phase, LPE decreased 5-lipoxygenase phosphorylation and COX-2 expression but not cPLA2 phosphorylation. Additionally, LPE included total phenolic compounds (10.72 mg/g dry weight) and total flavonoids (56.20 mg/g dry weight). These results suggest that the phenolic compounds or flavonoids contained in LPE may be associated with antiallergic activity. The phenolic compounds and flavonoids in LPE are antiallergic phytochemicals capable of inhibiting the activation of the FcεRI signaling cascade in mast cells. Such effects may provide further information for the development of a phytomedicine for allergic diseases.

Tricin Isolated from Enzyme-Treated Zizania latifolia Extract Inhibits IgE-Mediated Allergic Reactions in RBL-2H3 Cells by Targeting the Lyn/Syk Pathway

“…Histamine, secreted with β-hexosaminidase from mast cells, induces allergic inflammation, resulting in chronic allergic symptoms such as atopy, asthma, etc. Recent studies have reported the suppressive effects of flavonoids [21,22] and plant extracts [17] on mast cell degranulation. Among the various bioactive plant materials, Actinidia arguta extract has been recognized as a functional ingredient in facilitating the prevention of atopy, food allergy and asthma [23][24][25].…”

“…Following the immediate histamine release subsequent to antigen-mediated FcεRI aggregation, degranulation of mast cells results in the secretion of inflammatory mediators, including TNF-α, IL-4, leukotrienes and prostaglandins, which play key roles during the late phase of inflammatory reactions [16,17]. Inhibiting these mediators from activated mast cells is considered a promising strategy to ameliorate allergic responses.…”

“…Recently, efficacious edible plant materials devoid of any side effects are gaining attention as safe anti-allergic agents. RBL-2H3 cells express FcεRI on the cell membrane, and the IgE-bound FcεRI can be activated by antigens; thus, these cells are widely used for in vitro investigations on the mechanism of mast cell activation [16,17]. Mast cells play a major role in IgE-mediated allergic responses (hypersensitivity) by producing inflammatory mediators such as histamine, leukotrienes, prostaglandins and cytokines upon binding of an antigen to the IgE-bound high-affinity IgE receptor (FcεRI) [10].…”

“…Recently, efficacious edible plant materials devoid of any side effects are gaining attention as safe anti-allergic agents. RBL-2H3 cells express FcεRI on the cell membrane, and the IgE-bound FcεRI can be activated by antigens; thus, these cells are widely used for in vitro investigations on the mechanism of mast cell activation [16,17].…”

Inhibitory Effects of Viscum coloratum Extract on IgE/Antigen-Activated Mast Cells and Mast Cell-Derived Inflammatory Mediator-Activated Chondrocytes

“…Such effects of Viscum coloratum are associated with some bioactive compounds including flavonoids, lectins, phenolic compounds, sesquiterpene lactones, terpenes, and viscotoxins [ 9 , 10 , 11 , 12 , 13 ]. Recently, we showed that the aqueous extract of Loranthus parasiticus had anti-allergic actions in the IgE/Ag-mediated allergic responses in mast cells [ 23 ]. Moreover, activation of IgE-sensitized mast cells in articular tissues is associated with the initiation and/or aggravation of osteoarthritic diseases including rheumatoid arthritis [ 1 ].…”