Down-expression of Foxj1 on airway epithelium with impaired cilia architecture in non-cystic fibrosis bronchiectasis implies disease severity.

INTRODUCTION: The pathogenesis of non-cystic fibrosis bronchiectasis has not been clearly clarified. This study aimed to investigate the expression of ciliary regulating protein forkhead box protein j1 (Foxj1) on airway epithelium in non-cystic fibrosis bronchiectasis and its association with airway cilia structure disorder and disease severity. METHODS: Lung tissue sections excised from 47 patients with non-cystic fibrosis bronchiectasis were included between January 2018 and June 2021. Specimens from 26 subjects who underwent a lobectomy due to lung nodule were chosen as controls. Clinical information was collected, and pathologic analysis was performed to assess the epithelial structure and expression of ciliary regulating Foxj1. RESULTS: Of the 47 patients with non-cystic fibrosis bronchiectasis, 25 were considered as mild, 12 were moderate whereas the remaining 10 cases were severe according to the bronchiectasis severity index score evaluation. Epithelial hyperplasia, hyperplasia of goblet cells and inflammatory cell infiltration were observed in non-cystic fibrosis bronchiectasis, compared with control subjects. Cilia length in non-cystic fibrosis bronchiectasis patients were shorter than that in the control group, (5.34 ± 0.89) µm versus (7.34 ± 0.71) µm, respectively (P = 0.002). The expression of Foxj1 was (2.69 ± 1.09) × 106 in non-cystic fibrosis bronchiectasis, compared with (6.67 ± 1.15) × 106 in the control group (P = 0.001). Moreover, patients with lower expression of Foxj1 showed shorter airway cilia and worse in disease severity. CONCLUSION: Foxj1 declined in the airway epithelium of patients with non-cystic fibrosis bronchiectasis, positively correlated to cilia length and might imply worse disease severity.

IL-37 protects against airway remodeling by reversing bronchial epithelial-mesenchymal transition via IL-24 signaling pathway in chronic asthma.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is one of the mechanisms of airway remodeling in chronic asthma. Interleukin (IL)-24 has been implicated in the promotion of tissue fibrosis, and increased IL-24 levels have been observed in the nasal secretions and sputum of asthmatic patients. However, the role of IL-24 in asthmatic airway remodeling, especially in EMT, remains largely unknown. We aimed to explore the effect and mechanism of IL-24 on EMT and to verify whether IL-37 could alleviate IL-24-induced EMT in chronic asthma. METHODS: BEAS-2B cells were exposed to IL-24, and cell migration was assessed by wound healing and Transwell assays. The expression of EMT-related biomarkers (E-cadherin, vimentin, and α-SMA) was evaluated after the cells were stimulated with IL-24 with or without IL-37. A murine asthma model was established by intranasal administration of house dust mite (HDM) extracts for 5 weeks, and the effects of IL-24 and IL-37 on EMT and airway remodeling were investigated by intranasal administration of si-IL-24 and rhIL-37. RESULTS: We observed that IL-24 significantly enhanced the migration of BEAS-2B cells in vitro. IL-24 promoted the expression of the EMT biomarkers vimentin and α-SMA via the STAT3 and ERK1/2 pathways. In addition, we found that IL-37 partially reversed IL-24-induced EMT in BEAS-2B cells by blocking the ERK1/2 and STAT3 pathways. Similarly, the in vivo results showed that IL-24 was overexpressed in the airway epithelium of an HDM-induced chronic asthma model, and IL-24 silencing or IL-37 treatment could reverse EMT biomarker expression. CONCLUSIONS: Overall, these findings indicated that IL-37 mitigated HDM-induced airway remodeling by inhibiting IL-24-mediated EMT via the ERK1/2 and STAT3 pathways, thereby providing experimental evidence for IL-24 as a novel therapeutic target and IL-37 as a promising agent for treating severe asthma.