Targeting USP11 may alleviate radiation-induced pulmonary fibrosis by regulating endothelium tight junction

Abstract

Purpose Radiation-induced pulmonary fibrosis (RIPF) is a major side effect after radiotherapy for thoracic malignancies. However, rare anti-RIPF therapeutics show definitive effect for treating this disease. Ubiquitin-specific peptidase 11 (USP11) has been reported to promote transforming growth factor β (TGFβ) signaling which plays essential role underlying RIPF. Herein, we explored the role of USP11 on RIPF. Materials and Methods In the present study, USP11-knockout (Usp11-/- ) mice were used to explore the effects of USP11 on RIPF. The lung tissue was obtained after receiving 30Gy X-ray irradiation. The expression of USP11, TGF-β1, and a-SMA were determined by immunohistochemical and Western Blot, respectively. γ-H2AX foci and TUNEL positive cells were detected by fluorescent technique to assess DNA damage and apoptosis. High-throughput proteomics analysis was applied to further explore the related mechanisms. The transwell co-culture method was used to investigate bystander effects in HELF cells induced by irradiated HMEC-1 cells in vitro. Results Here we found that radiation activated USP11 in vivo and in vitro. Our results showed that USP11 deficiency effectively decreased serum TGF-β1 level, suppressed α-SMA expression and mitigated pulmonary fibrosis. In addition, fewer γ-H2AX foci and decreased apoptotic cells were identified after irradiation in the primary cells isolated from the lungs of Usp11-/- mice. High-throughput proteomics analysis results showed that 22-upregulated and 158-downregulated proteins were identified in the lung tissues of Usp11-/- mice after irradiation. Furthermore, gene set enrichment analysis (GSEA) revealed that USP11 deficiency affect tight junction signaling pathway. Conclusions We verified that USP11 deficiency remarkably reinforced tight junction in the endothelial cells and alleviated TGF-β1 to inhibit fibrosis of fibroblast cells. The present study preliminarily showed that USP11-knockout mitigated RIPF via reinforcement endothelial barrier function.