BACKGROUND

Diabetic foot ulcers (DFU), affecting a quarter of diabetic patients and leading to high rates of amputation and mortality, pose significant health and economic burdens. Wound healing in DFU is often compromised by chronic inflammation, underscoring the critical role of immune cells. However, the systematic investigation of immune-related genes (IRGs) in DFU pathogenesis remains elusive. To address this gap, our study aims to explore the association between IRGs and DFU.

METHODS

To explore biological changes in immune related gene expression in DFU, RNA-seq was performed on wound biopsies derived from 10 DFU patients and 11 healthy controls. Differentially expressed genes (DEGs) between DFU and normal samples were obtained by DEseq2. By intersecting the IRG list from the ImmPort database, the immune-related differentially expressed genes were identified. Function enrichment analysis and protein-protein interaction (PPI) analysis were applied by clusterProfiler and STRING database, and the hub genes of the PPI network were calculated by the cytoHubba plug-ins in Cytoscape. CIBERSORT algorithms was applied to analyze immune infiltration in DFU. And the correlation between immune cells infiltration and hub genes was explored by correlation analysis. Finally, to validate our findings, the transcriptional change of hub genes in DFU was confirmed using external scRNA-seq dataset and RT-qPCR.

RESULTS

RNA-seq analysis detected 8,800 DEGs in DFUs, with 2,351 upregulated and 6,449 downregulated.526 differential IRGs were obtained from intersection of DEGs and IRGs. 526 differential IRGs were obtained from intersection of DEGs and IRGs. Enrichment function analysis of DEGs showed that they played a significant role in immune response. The PPI network was constructed, and the most significant module containing 4 hub genes was identified. CIBERSORT analysis showing that there was a significant difference between DFU and normal controls in the infiltration of immune cells. Compared with normal tissue, DFU tissue contained a higher proportion of resting NK cell, M0 macrophages, and activated mast cell, while resting dendritic cell, activated mast cell, and activated NK cell contributed to a relatively lower portion. Additionally, the analysis for M1/M2 polarization of macrophage cells shown that DFU tissue contained a higher M1/M2 ratio than normal group. Finally, the expression levels of 4 hub genes were confirmed by external scRNA-seq dataset and RT-qPCR.

CONCLUSIONS

The immune related hub genes and the difference in immune infiltration between DFU tissue and normal controls might provide new insight for understanding DFU healing.