Single-cell transcriptomics combined with spatial transcriptomics reveals a fibrotic microenvironment in...

Hyperuricemia nephropathy (HN) is a kidney disease caused by hyperuricemia, with renal fibrosis as its hallmark lesion. Renal fibrosis involves diverse cell populations and complex intercellular communication, but its cellular composition and molecular mechanisms remain unclear.

We employed single-cell RNA sequencing and spatial transcriptomics to analyze kidney tissues from HN rats, identifying cell populations, gene expression patterns, and intercellular interactions. Differential gene-expression, pseudotime, gene-enrichment, and transcription factor network analyses were conducted.

Multiple cell types were identified, including macrophage/monocytes, epithelial cells, and endothelial cells. Macrophages/monocytes and injured proximal tubular cells played crucial roles in the fibrotic microenvironment. Compared with controls, HN rats showed increased epithelial cells and enhanced macrophage-epithelial interactions. Chemokine-mediated signaling pathways (C-C motif chemokine ligand 4 (Ccl4) - C-C motif chemokinereceptor 5 (Ccr5), Ccl3 - Ccr5 were significantly involved in fibrosis. Upregulated genes were enriched in pro-fibrotic pathways such as interleukin-17 and NF-κB, while downregulated genes were linked to metabolic pathways like glycolysis/gluconeogenesis and oxidative phosphorylation. In addition, in vivo experiments showed that the differentially upregulated genes heat shock protein beta-1 (Hspb1) and claudin 4 (Cldn4) were significantly expressed in the renal tissues of HN rats. In vitro gene knockdown experiments for Hspb1 and Cldn4 further validated their pro-fibrotic roles in renal fibrosis.

This study reveals key cellular and molecular mechanisms in HN fibrosis, identifying Hspb1 and Cldn4 as potential therapeutic targets. These findings provide new insights into the fibrotic microenvironment and may contribute to novel intervention strategies for HN treatment.