Silencing SMAD4 inhibits inflammation and ferroptosis in asthma by blocking the IL-17A signaling pathway

The TGF-β/SMAD signaling pathway is crucial in the pathogenesis of asthma. However, SMAD family member 4 (SMAD4), a key mediator of TGF-β, its roles and underlying mechanisms in asthma remain unclear.

Silencing SMAD4 prevents inflammation and ferroptosis in asthma by inhibiting the IL-17 pathway, which provides a novel potential approach for asthma therapy.

The in vivo and in vitro roles of SMAD4 in asthma were investigated through an ovalbumin (OVA)-induced mouse model and an interleukin-13 (IL-13)-induced cell model. The molecular mechanism of SMAD4 influenced asthma was examined using transcriptome sequencing, followed by feedback experiments involving recombinant human interleukin 17 A (rhIL-17 A), an IL-17 A signaling pathway activator.

SMAD4 was highly expressed in the asthma models. SMAD4 silencing alleviated damage to lung tissue and decreased inflammatory infiltration. Expression levels of Caspase-3, IgG, and inflammatory factors were reduced after silencing SMAD4. Silencing SMAD4 suppressed ferroptosis. Silencing SMAD4 also enhanced IL-13-induced BEAS-2B cell proliferation and suppressed apoptosis. Furthermore. IL-17 A signaling pathway was promoted in the asthma models, as evidenced by elevated IL-17RA, IL-17 A, and Act1 protein levels. SMAD4 silencing inhibited the expression levels of these IL-17 A pathway-associated proteins. Moreover, rhIL-17 A treatment notably reversed the impacts of SMAD4 silencing on asthma in the IL-13-induced cell model and OVA-induced mouse model, indicating that silencing SMAD4 inhibited inflammation and ferroptosis in asthma by blocking the IL-17 A signaling pathway.