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Kidney Week

Abstract: SA-PO086

Spatial Transcriptomics Enables Generation of a Complement Atlas of Mouse AKI

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Sabapathy, Vikram, University of Virginia, Charlottesville, Virginia, United States
  • Chauss, Daniel, NIH/NIDDK, Bethesda, Maryland, United States
  • Zheng, Shuqiu, University of Virginia, Charlottesville, Virginia, United States
  • Raju, Resmi, NICHD/NIH, Bethesda, Maryland, United States
  • Piña, Jeremie Oliver, NICHD/NIH, Bethesda, Maryland, United States
  • Sharma, Rahul, University of Virginia, Charlottesville, Virginia, United States
  • Freiwald, Tilo, University Med Ctr, Hamburg, Germany
  • Afzali, Behdad, NIH/NIDDK, Bethesda, Maryland, United States
  • Portilla, Didier, University of Virginia, Charlottesville, Virginia, United States
Background

Kidney tubulointerstitial fibrosis plays an essential role in progressive kidney disease. Our previous studies suggest that increased expression of intracellular complement (C’) components contribute to the pathogenesis of kidney fibrosis. The identity of the C’ components that participate in this process and cellular mechanisms involved in their activation remain under-explored. We hypothesized that increased local expression of C’ and its receptors directly in kidney tissue is compartmentalized and that local interactions involving this system impact fibrosis.

Methods

We used Spatial Transcriptomics (ST) by 10X Xenium, and formalin-fixed paraffin embedded (FFPE) kidney tissue from mice subjected to IRI and UUO to map all C’ components and their receptors (n=100 genes) in tandem with a multi-tissue atlasing panel (n=380 genes). Computational analyses included Seurat, integration by Harmony and clustering by UMAP.

Results

We generated a high-resolution map of C’ components and their receptors in control kidneys (Ctrl), UUO and IRI. Key C’ components were clearly differentially induced in AKI models compared to Ctrls. These included C3, factor B (CFB), factor H (CFH) and properdin (CFP). C3 and CFB were localized to failed to repair (FTR) PTs in AKI. CFH was highly induced in stromal cells , which were more than 3-fold expanded following AKI and UUO. CFP was localized to interstitial immune cells. We noted that infiltrating immune cells coalesced around FTR PTs and expressed the C3AR1 as well as receptors for C5a. The majority of immune cells were macrophages expressing high levels of F480, IL-1b and TNF, suggesting that they were proinflammatory macrophages. RNAscope, RT-PCR and confocal microscopy confirmed the changes seen by ST. The proximity of inflammatory immune cells expressing C3AR1 to PTs expressing their cognate ligand suggests bi-directional signaling between FTR PTs and immune cells. Ongoing work will functionally explore these observations and determine the local roles of CFH and CFP in AKI and fibrosis.

Conclusion

Compartmentalized induction of C’ components and receptors occurs following AKI and may modulate inflammation and subsequent fibrosis through interactions with local immune and stromal cells.

Funding

  • NIDDK Support