#994 Chronic kidney disease specific astrocyte is related with cognitive function

Abstract Background and Aims Chronic kidney disease (CKD) is increasingly recognized as a major global health burden, with neurological manifestations such as cognitive impairment and depression significantly contributing to patient disability. Despite the rising prevalence of cognitive decline in CKD, its underlying mechanisms remain poorly understood. This study aims to elucidate the mechanisms associated with cognitive impairment in CKD by utilizing single nucleus RNA sequencing of CKD-brain, providing novel insights into potential pathways and therapeutic targets. Method A rat model of chronic kidney disease (CKD) was established through 5/6 nephrectomy, followed by a 10-week observation period. Behavioral analyses were performed to assess cognitive function prior to brain tissue collection. The frontal lobe of the brain was then harvested for single-nucleus RNA sequencing (snRNA-seq), conducted using the 10× Chromium Single Cell 3’ v3.1 protocol (10× Genomics, document no. CG000315), to investigate transcriptional changes linked to cognitive impairment. Results The study identified eight cell type clusters, with astrocytes, excitatory neurons, and inhibitory neurons showing significant transcriptional changes in CKD. Total cell counts were higher in controls, but cell type proportions were comparable between groups. Astrocytes exhibited the most differentially expressed genes (DEGs), including upregulated Kcnj3 and Nmnat2 and downregulated Zmiz2. These findings, supported by pseudobulk analysis, highlight astrocytes’ key role in cognitive impairment in CKD. The results align with their involvement in other brain diseases, such as Alzheimer's and inflammatory conditions. Sub-clustering and trajectory analysis identified six astrocyte sub-clusters, with clusters 2, 3, and 5 showing increased proportions in CKD rats, indicating their role in CKD-related cognitive impairment. Cluster 4, with no proportional change, was linked to reactive astrocytes and inflammatory pathways. In contrast, cluster 5, unique to CKD, was associated with synaptic signaling, neurotransmitter receptors, and ion channel dysfunction. Pathway analysis revealed metabolic derangement in cluster 2, similar to Alzheimer's disease, and ferroptosis in cluster 3, a novel cell death mechanism. Collectively, CKD astrocytes exhibited distinct mechanisms of cognitive impairment, including metabolic disruption, ferroptosis, and synaptic dysfunction. Conclusion Astrocytes, especially CKD-specific sub-clusters, were identified as one of the most affected cells by snRNA-seq analysis. Our study demonstrated for the first time the heterogeneity of reactive astrocytes in response to the CKD environment. The presence of the CKD-specific astrocyte population suggested that the heterogeneity of reactive astrocytes could be a crucial target for future research. In addition, our findings would provide valuable insights into the pathogenesis of cognitive impairment in patients with CKD.