# TOP2A drives T-cell infiltration and immune remodeling in cyclophosphamide-induced cystitis: a single-cell sequencing study with potential implications for interstitial cystitis

## TL;DR

This study shows that TOP2A promotes T-cell infiltration in a rat model of bladder inflammation, suggesting it could be a new treatment target for interstitial cystitis.

## Contribution

The study identifies TOP2A as a novel driver of T-cell infiltration and immune remodeling in cyclophosphamide-induced cystitis.

## Key findings

- TOP2A is significantly upregulated in CYP-induced cystitis rat bladder tissues.
- TOP2A correlates strongly with CD4+ and CD8+ T-cell infiltration in the model.
- TOP2A is linked to oxidative phosphorylation and ribosomal pathways in bladder inflammation.

## Abstract

To explore the potential mechanisms of interstitial cystitis (IC), we employed a cyclophosphamide (CYP)-induced cystitis rat model, a well-established tool for studying IC-like bladder inflammation and dysfunction. This study aimed to investigate the role of rhythmic genes and immune microenvironment remodeling in this model, focusing on TOP2A and its impact on T-cell infiltration.

CYP-induced cystitis rat models were established using cyclophosphamide. Single-cell RNA sequencing was performed on bladder tissues to analyze cellular heterogeneity. Differentially expressed genes (DEGs) and weighted gene co-expression network analysis (WGCNA) identified rhythmic and immune-related gene clusters. TOP2A was validated via RT-PCR, Western blot, and immunohistochemistry (IHC). Statistical analyses assessed correlations between TOP2A, CD4 + T cells, and CD8 + T cells.

Single-cell sequencing revealed elevated T-cell infiltration in a CYP-induced cystitis rat model. TOP2A was the sole overlapping gene between rhythmic and immune clusters and showed significant upregulation in IC tissues (P < 0.05). IHC confirmed increased TOP2A, CD4 + T, and CD8 + T cell levels, with strong positive correlations (r = 0.89 and 0.64, respectively). Functional enrichment linked TOP2A to oxidative phosphorylation and ribosomal pathways.

Our findings demonstrate that TOP2A drives immune dysregulation in CYP-induced cystitis by modulating T-cell infiltration. As T-cell infiltration is a hallmark of human IC, our findings in this CYP-induced model suggest that TOP2A may represent a novel therapeutic target worthy of further investigation in human IC tissues.