Objective To explore the molecular mechanisms and cell-cell interactions in the injury process of pancreatic islet transplantation.

Methods Single-cell transcriptome data from mouse islets treated with inflammatory factors were used, and data processing was performed using the Seurat package, with integrated data to remove batch effects. Cell subpopulations were annotated based on known markers. Cell-cell interactions in the inflammatory factor-treated group were analyzed using the CellChat package, and inferred based on the expression of cell surface receptors and ligands. Gene set enrichment analysis was used to clarify the biological processes enriched in β-cells after treatment with inflammatory factors. Finally, differentially expressed transcription factors were identified and verified using microarray datasets of donor islet ischemic injury and Western blotting.

Results A total of 7 different cell subpopulations were found in mouse islets, with β-cells being the most abundant. Cell-cell interaction network analysis showed that the number and strength of interactions between ductal cells and other cells were the highest. Gene set enrichment analysis showed that after treatment with inflammatory factors, the immune response was positively enriched in β-cells, while peptide hormone metabolism, bile acid metabolism, and ion homeostasis were downregulated. The common differential transcription factors identified in the mouse single-cell transcriptome and the microarray dataset of donor islet ischemic injury were early growth response 1 (EGR1), nuclear factor-κB inhibitor α (NFKBIA), and activating transcription factor 3 (ATF3). Among them, NFKBIA and ATF3 were upregulated, while EGR1 was downregulated. The expression of EGR1 protein was downregulated after 24 h, 48 h, and 72 h of cold ischemia. Conclusions EGR1 is a transcription factor closely related to islet cold ischemia, and future research should focus on the specific mechanisms of EGR1 and its downstream target genes, in order to provide more effective strategies for clinical treatment of islet transplantation.