#6818 UNVEIL THE IMMUNE CELL LANDSCAPE IN AGEING KIDNEYS WITH AKI AND CKD

Abstract

Abstract Background and Aims Immunosenescence, or aging process of the immune system, leads to either defective immune response or increased systemic inflammation. Previous studies have shown that kidney immune system may coordinate the process of kidney inflammation, resolution, or progressive fibrosis in kidney diseases. However, the exact role of individual immune cell type has not been systematically characterized, especially in the context of ageing kidneys. Method Firstly, we induced acute and chronic aristolochic acid nephropathy (AAN) in 15-month-old mice. At different stages of AAN (Steady state, acute inflammation, recovery from acute injury, and chronic fibrosis), mice were then sacrificed, and kidneys were harvested for further processing. We flow-sorted kidney CD45+ immune cells (live cells) and applied to 10 x Genomics platform for single cell isolation and cDNA library construction. Illumina NovaSeq 6000 system was used for RNA sequencing. Finally, we performed downstream bioinformatics analysis through CellRanger and Seurat pipelines. Results Utilizing AAN mouse model, we successfully conducted flow sorted kidney immune cells single-cell RNA sequencing (scRNAseq) from 15 M/O kidneys with AKI and CKD. We clearly identified 25 distinctive immune cell types, representing distinctive lymphoid and myeloid populations (Figure 1a). We showed dynamic change of immune cell compositions upon different phases of AAN (i.e., CCR2+ monocytes and proliferative macrophages increased during acute inflammation, activated T cells expanded during recovery phase, CD206+CCL8+ macrophages enriched within the fibrotic kidneys) (Figure 1b). By analysis of differentially expressed genes (DEG), we identified 30 top-ranked genes, which uniquely enriched in specific cell subset (Figure 1c). Conclusion We have successfully unveiled the immune cell landscape in ageing kidneys with AKI and CKD. Our preliminary data has demonstrated that distinct immune cell subsets at different phases of injury may have unique roles. Future work will focus on the cell-cell interactions and immune cell activation/differentiation.