Abstract:

Objective

This study aims to analyze immune cell infiltration and key genes of in BKV nephropathy after renal transplantation based on transcriptomics.

Methods

We obtained microarray chip data from 17 renal tissue biopsies after renal transplantation from the GEO database.Through PCA dimensionality reduction analysis， differential expression analysis， enrichment analysis，PPI network construction and key gene screening， as well as cell infiltration analysis， combined with statistical methods such as the Wilcoxon ran-sum test and Spearman correlation analysis， we explored the patterns of immune cell infiltration and key genes in BKV nephropathy. The findings were subsequently validated through the external dataset GSE75693.

Results

The study found that biopsy samples from BKV nephropathy showed a distinct separation in gene expression patterns compared to normal renal transplant biopsy samples and BKV viremia renal tissue biopsy samples. Immune cell infiltration analysis revealed immune cell characteristics in BKV-related nephropathy， with significantly reduced proportions of plasma cells， resting mast cells， regulatory T cells， and activated NK cells （P ＜ 0.05）， while the proportions of resting CD4 memory T cells， memory B cells， activated CD4 memory T cells， and resting NK cells were significantly increased （P ＜ 0.05）. Identification of differentially expressed genes， GO and KEGG analyses， and PPI network construction with hub gene screening revealed that key genes such as KIF11， DLGAP5， CDK1， CDC20， BUB1， ASPM，KIF20A， BUB1B， TOP2A， and NUSAP1 showed varying degrees of correlation with the infiltration proportions of specific immune cell types （|r| ≥ 0.483， P ＜ 0.05）. The expression of these key genes was upregulated （|log₂ fold change| ≥ 1， P ＜ 0.001）. Validation results from the external dataset showed that TOP2A， CDC20， and KIF20A were significantly upregulated in BKV nephropathy biopsy samples （P ＜ 0.05）.

Conclusion

This study reveals the immune cell infiltration patterns and molecular characteristics of BKV nephropathy， providing new insights into the pathogenesis of BKV nephropathy and potential targets for future therapeutic strategies.

Key words: BK virus, Immune cell infiltration, Renal transplantation, BK virus nephropathy, Transcriptomics