Dictamnine Exhibits Anti-Asthmatic Effects by Modulating TGF-β/Smad2/3 Signaling in a Murine Asthma Model and Human Bronchial Epithelial Cells.

Current asthma therapies reduce inflammation and symptoms but there are concerns regarding adverse effects and the long-term treatment burden. The anti-asthmatic potential of Dictamnine (Dic) has not been investigated. The therapeutic effect of Dic on airway inflammation and remodeling was investigated by targeting the tumor growth factor (TGF)-β/Smad2/3 pathway. A murine model of ovalbumin (OVA)-induced asthma was used to evaluate the effects of orally-administered Dic on airway hyperresponsiveness, inflammatory cytokines in bronchoalveolar lavage fluid (BALF), OVA-specific IgE in the serum, and histopathological changes. The expression of TGF-β/Smad2/3 and epithelial markers was assessed. Human bronchial epithelial cells were used in vitro to examine the effects of Dic on TGF-β-induced Smad2/3 phosphorylation. Network pharmacology was conducted to predict Dic-associated targets and pathways. Dic substantially reduced the levels of Th2 cytokines, mucin 5AC in BALF, and OVA-specific IgE in the serum. Histology indicated reduced inflammatory cell infiltration, bronchial wall thickening, and peribronchial fibrosis in Dic-treated mice. Dic downregulated TGF-β and p-Smad2/3 expression and upregulated ZO-1 expression in the lung tissue. Dic downregulated TGF-β-induced Smad2/3 phosphorylation in bronchial epithelial cells. Network pharmacology indicated enrichment of Dic-related genes in the TGF-β pathway. Dic exhibited anti-asthmatic effects and is a potential therapeutic candidate.