Silibinin, a PLC-β3 inhibitor, inhibits mast cell activation and alleviates OVA-induced asthma

The immunoglobulin E (IgE) receptor FcεRI (Fc epsilon RI) plays a crucial role in allergic reactions. Recent studies have indicated that the interaction between FcεRIβ and the downstream protein phospholipase C beta 3 (PLCβ3) leads to the production of inflammatory cytokines. The aim of this study was to develop small molecules that inhibit the protein-protein interactions between FcεRIβ and PLCβ3 to treat allergic inflammation. Additionally, PLCβ3 has emerged as a potential target protein for treating allergic inflammation. In this study, we employed a virtual screening technique to search the Taiwan Traditional Chinese Medicine Database, followed by a second screening using absorption, distribution, metabolism, excretion, and toxicity (ADMET). Among the compounds screened, silibinin exhibited the best performance, forming strong hydrogen bond interactions with residues of PLCβ3, with a binding free energy of -119.277 kcal/mol. Therefore, silibinin effectively blocked the interaction between FcεRIβ and PLCβ3. Silibinin reduced the production of allergic inflammatory cytokines, including cytokine-induced neutrophil chemoattractant 2a (CINC-2a), interleukin-2 (IL-2), cytokine-induced neutrophil chemoattractant 1 (CINC-1), interleukin 1α (IL-1α), macrophage inflammatory protein 3 alpha (MIP3α), interferon γ (IFN-γ), activin A, granulocyte macrophage colony stimulating factor (GM-CSF), intercellular adhesion molecule-1 (ICAM-1), interleukin 4 (IL-4), interleukin 13 (IL-13), Fas ligand (FasL) and tumor necrosis factor alpha (TNF-α), without inducing cytotoxicity. Furthermore, in studies of IgE-mediated allergic responses, silibinin also decreased the expression of surface IgE receptors (FcεRIs). Moreover, silibinin effectively alleviated allergen-induced asthma responses and reduced the infiltration of inflammatory immune cells into the lungs of an OVA-induced allergic airway inflammation mouse model. Taken together, these results demonstrate the potential antiallergic mechanism of silibinin both in vitro and in vivo, making it a promising candidate for the development of asthma therapeutics.