Integrated Molecular Docking and Dynamic Simulations Reveal Glycyrrhizic Acid Alleviates Allergic Rhinitis in Rats by Inhibiting the TLR4/NF‐κB/IL‐1β Pathway

Abstract

Background Allergic rhinitis (AR) is a prevalent chronic inflammatory nasal disorder with suboptimal current therapies. Glycyrrhizic acid (GA), a bioactive triterpenoid from Glycyrrhiza uralensis, exerts well‐documented antiinflammatory effects, and preliminary evidence indicates its efficacy in alleviating airway inflammation in AR models. However, two critical knowledge gaps remain unaddressed: whether GA directly binds to core proteins of the toll‐like receptor 4 (TLR4)/nuclear factor‐kappa B (NF‐κB)/IL‐1β inflammatory pathway, and whether this binding mediates GA’s therapeutic effects in AR have not been systematically verified by integrated computational and in vivo experiments. Methods An ovalbumin (OVA)‐induced AR rat model was established. GA was administered intranasally for seven consecutive days. Behavioral observations, histopathological examination, and serum cytokine detection were performed to evaluate AR‐related symptoms and immune imbalance. Molecular docking was employed to assess the binding affinity between GA and four key proteins in the TLR4 pathway (TLR4, myeloid differentiation primary response 88 [MyD88], NF‐κB, and IL‐1β). About 100 ns molecular dynamics (MD) simulations were further conducted to validate the stability of the GA–protein complexes. Immunohistochemistry and RT‐qPCR were used to verify the expression of pathway‐related proteins and cytokines in nasal mucosal tissues. Results GA significantly reduced sneezing, rhinorrhea, and nasal mucosal pathological damage in AR rats. It restored the T helper 1 (Th1)/Th2 immune balance by suppressing Th2 cytokines (IL‐4 and IL‐13) and enhancing Th1 cytokines (interferon‐gamma [IFN‐γ] and IL‐2). Molecular docking results showed that GA bound strongly to all four target proteins, with the highest affinity for IL‐1β (−9.3 kcal/mol) and TLR4 (−7.6 kcal/mol). MD simulations confirmed the stable conformational dynamics of the GA–IL‐1β and GA–TLR4 complexes. In vivo experiments further demonstrated that GA significantly downregulated the expression of TLR4, MyD88, NF‐κB, and IL‐1β in nasal mucosa and reduced the levels of downstream proinflammatory cytokines (TNF‐α and IL‐6). Conclusions GA alleviates AR symptoms by directly binding to core proteins of the TLR4/NF‐κB/IL‐1β pathway, inhibiting pathway activation, restoring Th1/Th2 immune balance, and suppressing inflammatory responses. This study provides structural and functional evidence supporting GA as a promising targeted therapeutic candidate for AR.