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Kidney Week

Abstract: FR-PO1066

Elucidating the Function of a Novel Arg-1+/Clec4d+ Scar-Associated Monocyte-Derived Macrophage Population in Driving Fibrosis in Kidney Disease Models

Session Information

Category: CKD (Non-Dialysis)

  • 2303 CKD (Non-Dialysis): Mechanisms

Authors

  • Bell, Rachel, University of Edinburgh, Edinburgh, United Kingdom
  • Denby, Laura, University of Edinburgh, Edinburgh, United Kingdom
  • Conway, Bryan, University of Edinburgh, Edinburgh, United Kingdom
  • Bénézech, Cécile, University of Edinburgh, Edinburgh, United Kingdom
Background

Fibrosis is the final common pathway in all progressive kidney disease. Macrophages are a major myeloid cell component of the renal mononuclear phagocyte system, with roles in defence against infection, renal injury, and repair. Using single-cell RNA sequencing, we identified a novel myeloid cell subset exclusively present in acute injury of the unilateral ureteric obstruction (UUO) model of kidney fibrosis. This population transcriptomically aligns to monocytes but is enriched for both Arginase-1 (Arg1) and the C-type lectin 4d (Clec4d) and a large number of pro-inflammatory and pro-fibrotic genes. We hypothesise that this novel Arg1+/Clec4d+ population contributes to fibrosis deposition in progressive kidney disease.

Methods

The presence of the Arg1+/Clec4d+ cells was validated in the UUO, unilateral ischaemic reperfusion injury (uIRI) and subtotal nephrectomy models of kidney injury.

Results

Analysis of intra-renal inflammation revealed CD45+CD11b+Arg1+ cells persisted and increased in number across 7 days in our injury models. Post-injury, Arg1+ cells were confirmed to be Clec4dhi. As time progressed post-injury, consistent with a monocyte to macrophage transition, there was a decrease in Ly6C but increase in F4/80, MHCII and CD206 expression in this subset. To confirm that Arg1+/Clec4d+ cells were derived from monocytes (Ccr2+), we administered tamoxifen to Ccr2CreERT2-TdTomato mice under a single or multiple-dose regimen following UUO surgery. At day 7 post-injury, ~50% and ~90% of the Arg1+ cells were TdTomato+ following a single or multiple doses of tamoxifen, respectively, suggesting that these cells are primarily monocyte derived. Moreover, the Arg1+/Clec4d+ cells were found to localise to areas of scarring. To investigate the therapeutic potential of targeting Clec4d+ expressed on the Arg1+/Clec4d+ macrophages, mice underwent UUO surgery and were given multiple doses of a Clec4d-neutralising antibody. A decrease in Arg1 and fibrosis-related gene expression was evident by day 7 post-injury.

Conclusion

Further investigation into targeting this population in kidney disease has the potential to aid the development of novel therapeutics to limit fibrosis and halt progression of disease.

Funding

  • Clinical Revenue Support