MMP9 in macrophages: A pivotal biomarker associated with immune dysregulation in interstitial cystitis/bladder pain syndrome.

BACKGROUND

Studies suggest that immune abnormalities play a significant role in the pathophysiology of interstitial cystitis/bladder pain syndrome (IC/BPS), yet reliable targets and biomarkers for immune intervention remain unidentified. The aim of this study was to explore the immune key targets and biomarkers that are crucial in IC/BPS.

METHODS

Single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (bulk RNA-seq) data were integrated to analyze the immune microenvironment in IC/BPS. scRNA-seq data (GSE164557) were processed with the Seurat package, while bulk RNA-seq data (GSE11783, GSE11839, GSE28242, GSE57560) were batch-corrected using limma. Differential expression analysis was performed with limma, and immune cell infiltration was assessed through CIBERSORT. A binary classification machine learning model was built using 14 algorithms to identify key genes. Functional enrichment and gene regulatory networks were analyzed using GSEA, ORA, and pySCENIC.

RESULTS

Our findings revealed substantial dysregulation of immune cell homeostasis in IC/BPS patients, characterized by aberrant macrophage polarization and T cell subset dysregulation. MMP9 has been identified as a key gene that is highly expressed in IC/BPS, particularly in macrophages. Functional annotation showed that MMP9 expression is positively correlated with the enrichment of immune pathways such as leukocyte activation and phagocytosis, and single-cell analysis demonstrated enhanced phagocytic activity in MMP9+ macrophages. Additionally, potential MMP9-targeting drugs, including teriflunomide, captopril, minocycline, and ilomastat, were identified through CMap database screening and molecular docking.

CONCLUSION

This study highlights MMP9 as a key macrophage biomarker in IC/BPS, where its elevated expression is closely linked to enhanced phagocytic activity and the activation of immune-related signaling pathways.