Cathepsin G promotes arteriovenous fistula maturation by positively regulating the MMP2/MMP9 pathway

Abstract

Background

Arteriovenous fistula (AVF) is currently the preferred vascular access for hemodialysis patients. However, the low maturation rate of AVF severely affects its use in patients. A more comprehensive understanding and study of the mechanisms of AVF maturation is urgently needed.

Methods and results

In this study, we downloaded the publicly available datasets (GSE119296 and GSE220796) from the Gene Expression Omnibus (GEO) and merged them for subsequent analysis. We screened 84 differentially expressed genes (DEGs) and performed the functional enrichment analysis. Next, we integrated the results obtained from the degree algorithm provided by the Cytohubba plug-in, Molecular complex detection (MCODE) plug-in, weighted gene correlation network analysis (WGCNA), and Least absolute shrinkage and selection operator (LASSO) logistic regression. This integration allowed us to identify CTSG as a hub gene associated with AVF maturation. Through the literature search and Pearson’s correlation analysis, the genes matrix metalloproteinase 2 (MMP2) and MMP9 were identified as potential downstream effectors of CTSG. We then collected three immature clinical AVF vein samples and three mature samples and validated the expression of CTSG using immunohistochemistry (IHC) and double-immunofluorescence staining. The IHC results demonstrated a significant decrease in CTSG expression levels in the immature AVF vein samples compared to the mature samples. The results of double-immunofluorescence staining revealed that CTSG was expressed in both the intima and media of AVF veins. Moreover, the expression of CTSG in vascular smooth muscle cells (VSMCs) was significantly higher in the mature samples compared to the immature samples. The results of Masson’s trichrome and collagen I IHC staining demonstrated a higher extent of collagen deposition in the media of immature AVF veins compared to the mature. By constructing an in vitro CTSG overexpression model in VSMCs, we found that CTSG upregulated the expression of MMP2 and MMP9 while downregulating the expression of collagen I and collagen III. Furthermore, CTSG was found to inhibit VSMC migration.

Conclusions

CTSG may promote AVF maturation by stimulating the secretion of MMP2 and MMP9 from VSMCs and reducing the extent of medial fibrosis in AVF veins by inhibiting the secretion of collagen I and collagen III.

Keywords:

• Bioinformatic analysis
• arteriovenous fistula
• vascular smooth muscle cells
• CTSG
• non-maturation

Acknowledgments

Not applicable.

Statement of ethics

The study protocol was reviewed and approved by the Ethics Committee of Guangzhou First People’s Hospital and was in accordance with the principles of the Declaration of Helsinki [approval number: K-2022-011-01]. Written informed consent was obtained from all the participants.

Author contributions

Ming Liang, Quhuan Li, Lemei Hu, and Changqing Zheng conceived and designed the study. Lemei Hu designed and performed experiments. Lemei Hu and Changqing Zheng analyzed the data and drafted the manuscript. Ming Liang, Quhuan Li, Lemei Hu, and Changqing Zheng reviewed and edited the manuscript. Lemei Hu, Fengzhang Huang, and Zhigang Zhu contributed to data collection. Ying Kong and Zhiqing Luo provided guidance on data analysis. All the authors have read and agreed to the published version of the manuscript.

Disclosure statement

The authors declared that they have no conflict of interest.

Data availability statement

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (grant numbers: 82170761 and 81770677) and Guangzhou Key Discipline of Medicine (Geriatric Medicine, 2021-2023, ZDXK202103).