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Trifolirhizin mitigates ovalbumin-induced lung inflammation and tissue damage in neonatal rats via inhibition of the NF-κB signaling pathway
Abstract
Purpose: To investigate the effect of trifolirhizin on neonatal rat model of asthma, and the mechanism of action involved.
Methods: Neonatal rats (n = 50) were randomly assigned to 5 groups (10 pups/group): sham, asthma and three treatment groups. With the exception of sham group, the rat pups were sensitized intraperitoneally with ovalbumin (OVA) at a dose of 20 µg/kg on days 7 and 21 postpartum. Rats in the treatment groups received trifolirhizin intragastrically at doses of 2, 4 and 5 mg/kg on day 7 postpartum. Eosinophils in bronchoalveolar lavage fluid (BALF) were counted using hematological analyzer. Serum immunoglobulin (Ig)E and interleukin (IL)-4, IL-5 and IL-13 levels in BALF were determined using their respective enzyme-linked immunosorbent assay (ELISA) kits. Messenger RNA (mRNA) expressions of mucin 5AC (Muc5AC), mucin 5B (Muc5B), tumor necrosis factor α (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) were determined using immunohistochemical staining, while the protein expression of inhibitor of nuclear factor of kappa light polypeptide gene enhancer in B-cells alpha (IκBα) was assayed by Western blotting.
Results: Serum IgE level was significantly higher in asthma group than in sham group, but was significantly and dose-dependently reduced after treatment with trifolirhizin (p < 0.05). Lung tissue damage was also significantly mitigated in the treatment groups, relative to asthma group (p < 0.05). Trifolirhizin treatment significantly and dose-dependently downregulated the mRNA expressions of Muc5AC, Muc5B, TNF-α and ICAM-1, but upregulated IκBα protein expression significantly and dosedependently (p < 0.05). Bronchoalveolar lavage fluid (BALF) levels of IL-4, IL-5 and IL-13 were significantly higher in asthma group, but were significantly and dose-dependently reduced after treatment with trifolirhizin (p < 0.05).
Conclusion: These results indicate that trifolirhizin mitigates OVA-induced lung inflammation and tissue damage in neonatal rats via inhibition of NF-κB signaling pathway, thus affording a potential therapeutic strategy for the management of asthma