Toll-like receptor 4 mediated autophagy regulates airway smooth muscle cells behavior

Airway remodeling, a prominent feature of asthma, involves aberrant proliferation, apoptosis, and migration of airway smooth muscle cells (ASMCs). Toll-like receptors (TLRs) are implicated in the regulation of the autophagy pathway. In this study, we aimed to investigate the influence of Toll-like receptor 4 (TLR4) on autophagy and its underlying mechanism in ASMC proliferation, apoptosis, and migration.

Histopathological changes in the lungs of asthmatic mice assessed by Hematoxylin-Eosin (HE) and Masson staining. Cell proliferation, apoptosis and migration were evaluated utilizing CCK8, Edu, Flow cytometry and wound heading assays. The effectiveness of siRNA transfection and the expression of TLR4, autophagy, and proliferation-related proteins after siRNA treatment were examined through RT-PCR and Western blot (WB).

We observed an increase in TLR4 expression and autophagy in a mouse model of OVA-induced asthma. In vitro experiments showed that siRNA-mediated inhibition of TLR4 suppressed autophagy, proliferation, and migration of ASMCs, whereas TLR4 activation by lipopolysaccharide (LPS) had the opposite effect. Furthermore, the autophagy inhibitor 3-Methyladenine (3MA) inhibited ASMCs proliferation and migration while promoting apoptosis. Significantly, our study demonstrated that autophagy inhibition reversed the promotion effect of LPS on ASMC proliferation and migration. These findings suggest that TLR4 may modulate ASMC behavior through the regulation of autophagy.