Epithelial CST1 Promotes Airway Eosinophilic Inflammation in Asthma via the AKT Signaling Pathway

Lijuan Du; Changyi Xu; Kun Tang; Jia Shi; Lu Tang; Xiao Lisha; Chengcheng Lei; Huicong Liu; Yuxia Liang; Yubiao Guo

doi:10.4168/aair.2023.15.3.374

Epithelial CST1 Promotes Airway Eosinophilic Inflammation in Asthma via the AKT Signaling Pathway

Allergy Asthma Immunol Res. 2023 May;15(3):374-394. doi: 10.4168/aair.2023.15.3.374. Epub 2023 Mar 8.

Authors

Lijuan Du^#^{1

2

3}, Changyi Xu^#^{1

2}, Kun Tang^{1

2}, Jia Shi^{1

2}, Lu Tang^{1

2}, Xiao Lisha^{1

2}, Chengcheng Lei^{1

2}, Huicong Liu^{1

2}, Yuxia Liang^{1

4}, Yubiao Guo^{1

5}

Affiliations

¹ Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
² Institute of Respiratory Diseases of Sun Yat-Sen University, Guangzhou, China.
³ Department of Respiratory and Critical Care Medicine, Affiliated Hospital of Guizhou Medical University, Guiyang, China.
⁴ Institute of Respiratory Diseases of Sun Yat-Sen University, Guangzhou, China. liangyx69@mail.sysu.edu.cn.
⁵ Institute of Respiratory Diseases of Sun Yat-Sen University, Guangzhou, China. guoyb@mail.sysu.edu.cn.

^# Contributed equally.

Abstract

Purpose: Epithelial cystatin SN (CST1), a type 2 cysteine protease inhibitor, was significantly upregulated in asthma. In this study, we aimed to investigate the potential role and mechanism of CST1 in eosinophilic inflammation in asthma.

Methods: Bioinformatics analysis on Gene Expression Omnibus datasets were used to explore the expression of CST1 in asthma. Sputum samples were collected from 76 asthmatics and 22 control subjects. CST1 mRNA and protein expression in the induced sputum were measured by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and western blotting. The possible function of CST1 was explored in ovalbumin (OVA)-induced eosinophilic asthma. Transcriptome sequencing (RNA-seq) was used to predict the possible regulated mechanism of CST1 in bronchial epithelial cells. Overexpression or knockdown of CST1 was further used to verify potential mechanisms in bronchial epithelial cells.

Results: CST1 expression was significantly increased in the epithelial cells and induced sputum of asthma. Increased CST1 was significantly associated with eosinophilic indicators and T helper cytokines. CST1 aggravated airway eosinophilic inflammation in the OVA-induced asthma model. In addition, overexpression of CST1 significantly enhanced the phosphorylation of AKT and the expression of serpin peptidase inhibitor, clade B, member 2 (SERPINB2), while knockdown using anti-CST1 siRNA reversed the trend. Furthermore, AKT had a positive effect on SERPINB2 expression.

Conclusions: Increased sputum CST1 may play a key role in the pathogenesis of asthma through involvement in eosinophilic and type 2 inflammation through activation of the AKT signaling pathway, further promoting SERPINB2 expression. Therefore, targeting CST1 might be of therapeutic value in treating asthma with severe and eosinophilic phenotypes.

Keywords: Asthma; SERPINB2; cystatin SN; eosinophils; epithelium; inflammation; ovalbumin.