METTL3 destabilizes RFX7 to ameliorate PDGF-BB-induced airway smooth muscle cell dysfunction and inflammation in an in vitro model of childhood asthma.

BACKGROUND

Childhood asthma represents a significant global health burden, characterized by chronic airway inflammation and remodeling. Regulatory factor X7 (RFX7) has emerged as a potential key player in asthma pathogenesis. However, its specific role in modulating airway smooth muscle cell (ASMC) dysfunction-a hallmark of asthma pathology-remains poorly understood.

METHODS

An in vitro asthma model was established by stimulating airway smooth muscle cells (ASMCs) with platelet-derived growth factor-BB (PDGF-BB). Quantitative real-time PCR (qRT-PCR) and Western blotting were employed to measure the mRNA and protein expression levels of RFX7 and METTL3, respectively. Functional assays, including 5-ethynyl-2'-deoxyuridine incorporation, Transwell, and wound-healing assays, were utilized to evaluate ASMC proliferation, invasion, and migration. Inflammatory responses were assessed by enzyme-linked immunosorbent assays (ELISAs) targeting interleukin-6 (IL-6).

RESULTS

RFX7 expression levels were significantly elevated in the serum of pediatric asthma patients and in PDGF-BB-induced ASMCs, whereas METTL3 expression was downregulated. PDGF-BB stimulation enhanced ASMC proliferation, invasion, and migration, all of which were markedly attenuated by RFX7 knockdown. Furthermore, RFX7 deficiency reduced PDGF-BB-induced production of IL-6, TNF-α, ROS, and MDA, as well as the proportion of CD86-positive macrophages. Notably, METTL3 exhibited a negative correlation with RFX7 in patient sera and destabilized RFX7 transcripts in a YTHDF2-dependent manner. Consequently, overexpression of METTL3 alleviated PDGF-BB-induced ASMC dysfunction by downregulating RFX7.

CONCLUSION

METTL3-mediated destabilization of RFX7 ameliorated PDGF-BB-induced ASMC proliferation, migration, and invasion, while simultaneously suppressing inflammation, oxidative stress, and macrophage polarization. Targeting this METTL3-RFX7 axis may offer a novel therapeutic strategy to mitigate airway remodeling and inflammation in childhood asthma.