TRIM33 Modulates Inflammation and Airway Remodeling of PDGF-BB-Induced Airway Smooth-Muscle Cells by the Wnt/β-Catenin Pathway

Asthma is a chronic airway disease involving airway inflammation and remodeling. Studies showed that tripartite motif-containing protein 33 (TRIM33) regulated natural immunity, inflammation, and pulmonary fibrosis. However, the role and regulatory mechanism of TRIM33 in children's asthma are unclear. In this study, the TRIM33 expressions in serum samples and platelet-derived growth factor BB (PDGF-BB)-induced airway smooth-muscle cells (ASMCs) were evaluated. A gain-of-function experiment was performed, and cell proliferation and migration were detected using CCK-8 and wound healing assays. Besides, the protein levels of EMT biomarkers and airway-remodeling markers were determined by Western blot assay. ELISA analyzed the contents of IL-1β, IL-6, and TNF-α in the supernatant. The modulation of Smad4 expression and subsequent activation of Wnt/β-catenin by TRIM33 were also assessed. We found that TRIM33 was downregulated in the serum from children who were asthma patients and PDGF-BB-induced ASMCs. TRIM33 overexpression showed decrease of PDGF-BB-induced ASMC proliferation and migration. Moreover, the augment of TRIM33 reduced the PDGF-BB-induced cell EMT and airway-remodeling marker levels and suppressed the secretions of inflammatory cytokines in PDGF-BB-induced ASMCs. Additionally, TRIM33 overexpression inhibited activation of Wnt/β-catenin via reducing Smad4 expression to regulate asthma inflammation and airway remodeling. All in all, our study revealed that TRIM33 expression was downregulated in children who were asthma patients and PDGF-BB-induced ASMCs. TRIM33 modulated PDGF-BB-induced inflammation and airway remodeling of ASMCs by the Wnt/β-catenin pathway via regulating Smad4, which may provide a new treatment direction for asthma.