Single-cell sequencing dissects the transcriptional identity of activated fibroblasts and identifies novel persistent distal tubular injury patterns in kidney fibrosis

Abstract

Examining kidney fibrosis is crucial for mechanistic understanding and developing targeted strategies against chronic kidney disease (CKD). Persistent fibroblast activation and tubular epithelial cell (TEC) injury are key CKD contributors. However, cellular and transcriptional landscapes of CKD and specific activated kidney fibroblast clusters remain elusive. Here, we analyzed single cell transcriptomic profiles of two clinically relevant kidney fibrosis models which induced robust kidney parenchymal remodeling. We dissected the molecular and cellular landscapes of kidney stroma and newly identified three distinctive fibroblast clusters with “secretory”, “contractile” and “vascular” transcriptional enrichments. Also, both injuries generated failed repair TECs (frTECs) characterized by decline of mature epithelial markers and elevation of stromal and injury markers. Notably, frTECs shared transcriptional identity with distal nephron segments of the embryonic kidney. Moreover, we identified that both models exhibited robust and previously unrecognized distal spatial pattern of TEC injury, outlined by persistent elevation of renal TEC injury markers including Krt8, while the surviving proximal tubules (PTs) showed restored transcriptional signature. Furthermore, we found that long-term kidney injuries activated a prominent nephrogenic signature, including Sox4 and Hox gene elevation, which prevailed in the distal tubular segments. Our findings might advance understanding of and targeted intervention in fibrotic kidney disease.

Insights into Repeated Renal Injury Using RNA-Seq with Two New RPTEC Cell Lines

“…We examined expression changes over concentrations that showed similar trends in a time course experiment. Elevation in nephrogenesis hox genes, notably Hoxc12 and Hoxc13, are consistent with other reports describing Hox upregulation during long-term, pathologic kidney remodeling [51]. Increased Il6 and Il18 are known cytokines in acute renal injury [52]; we also observed increased expression of several other transcripts contributing to a renal immune response after CisPt, including Itk [53], Ptafr [54], Selp [55], Hc [56], and Nlrp12 [57].…”

Gclc as a Marker for Injured Distal Nephron in Ischemia-Reperfusion Induced Acute Kidney Injury

“… 24 , 25 Long-term renal injury has been found to result in increased expression of Sox4 and Hox genes in distal tubular segments. 26 However, the patterns of acute-phase injury in these segments remain poorly understood. Consequently, a thorough evaluation of crucial molecules and intercellular communication linked to distal renal tubular injury in AKI is necessary.…”