Theranostics 2021; 11(14):7110-7125. doi:10.7150/thno.61085 This issue
1. Department of Respiratory and Critical Care Medicine, Key Laboratory of Pulmonary Diseases of National Health Commission, Key Site of National Clinical Research Center for Respiratory Disease, Wuhan Clinical Medical Research Center for Chronic Airway Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, 1095 Jiefang Ave, Wuhan 430030, China.
2. Department of Pulmonary and Critical Care Medicine, Center of Respiratory Medicine, China-Japan Friendship Hospital, 100029, Beijing, China.
3. Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, 1095 Jiefang Ave, Wuhan 430030, China.
4. Department of Respiratory and Critical Care Medicine, Shanghai Key Laboratory of Tissue Engineering, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Lu, Shanghai, 200011, China.
5. The Center for Biomedical Research, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, 1095 Jiefang Ave, Wuhan 430030, China.
#These authors contributed equally to this work.
Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive fatal interstitial lung disease characterized by abnormal transition and proliferation of fibroblasts. The uncontrolled transition of fibroblasts, commonly known as myofibroblasts, are the principal source of the enormous extracellular matrix (ECM) depositing in lung parenchyma, leading to gradual failure of gas exchange and mortality of the patients. However, up to now, rare effective therapeutic strategies have been developed to blockade fibroblast-to-myofibroblast transition (FMT) in IPF.
Method: We illustrated that the lungs originated from IPF patients and mice with pulmonary fibrosis are characterized by the overexpression of sushi-repeat-containing protein, X-linked 2 (SRPX2). Further functionality studies identified the pivotal role of SRPX2 in FMT. Mechanistically, SRPX2 was involved in a TGFβR1/SMAD3/SRPX2/AP1/SMAD7 positive feedback loop. Specifically, SRPX2 was upregulated by TGF-β1 in a TGFβR1/SMAD3-dependent manner, after which SRPX2 in turn repressed the expression of AP1, subsequently minimized SMAD7 expression, through which it reduced the formation of inhibitory complex with TGFβR1 and enhanced SMAD signaling pathway to promote FMT and exacerbate pulmonary fibrosis. Notably, intratracheal administration of siRNA-loaded liposomes could effectively suppress the expression of Srpx2 in the lung and remarkably protect mice against BLM-induced pulmonary fibrosis, concomitant with a significant reduction of FMT.
Results: Accordingly, these data indicate that Srpx2 plays an essential role in the pathogenesis of pulmonary fibrosis and suggests the strategy aiming at silencing Srpx2 could be a promising therapeutic approach against pulmonary fibrosis in clinical settings.
Keywords: idiopathic pulmonary fibrosis, fibroblasts, myofibroblasts, SRPX2, liposomes