Kidney Week

Abstract: FR-PO147

Loss of C5aR1 in Foxd1+ Stromal Cells Reduces Kidney Fibrosis

Session Information

• Molecular Mechanisms of CKD - II
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 1903 CKD (Non-Dialysis): Mechanisms

Authors

• Sahu, Ranjit K., University of Virginia, Charlottesville, Virginia, United States

Ranjit K. Sahu,

• Xavier, Sandhya, University of Virginia/Department of Medicine, Charlottesville, Virginia, United States

Sandhya Xavier,

• Portilla, Didier, University of Virginia Health System, Charlottesville, Virginia, United States

Didier Portilla,

Background

Recent studies have identified a population of perivascular mesenchymal cells in the kidney that express the transcription factor Foxd1. These cells are called resident fibroblasts or pericytes. Fate-mapping studies have identified these pericytes and resident fibroblasts as the major precursor population of interstitial myofibroblasts in animal models of kidney disease. We previously reported increased synthesis of complement components including anaphylatoxin receptor C5aR1 in PDGFβR-positive pericytes isolated from murine models of fibrosis. Reduced expression of C5aR1 using global deletion of C5aR1 ameliorates renal fibrosis. We hypothesize that deletion of C5aR1 in Foxd1-expressing cells can lead to reduced myofibroblast production, reduced inflammation, and reduced kidney fibrosis.

Methods

C5aR1GFP^fl/fl mice were generated by inserting LoxP sites flanking exon 2 as previously reported. C5aR1GFP^fl/fl mice were crossed with mice expressing Cre-recombinase under control of the Foxd1 promoter to generate Foxd1-Cre-C5aR1GFP^fl/fl mice. Eight week old Foxd1-Cre-C5aR1GFP^fl/fl mice and C5aR1GFP^fl/fl (control mice) received intraperitoneal injections of either vehicle (sodium bicarbonate) or folic acid+sodium bicarbonate (FA). Two weeks later kidney tissue was harvested for analysis. Primary mouse pericytes were isolated from the kidneys of Foxd1CreC5aR1GFP^fl/fl and C5aR1GFP^fl/fl following FA-injury as previously reported

Results

Immunohistochemical analysis, flow cytometry, quantitative RT-PCR and western blots demonstrated reduced inflammation and reduced fibrosis in whole kidney tissue from Foxd1CreC5aR1GFP^fl/fl mice treated with FA when compared to control mice. Cytokine production measured by Luminex assays in cell supernatants from cultured PDGFβR⁺ cells isolated from kidneys of FA-treated mice demonstrated that the absence of C5aR1 receptor in cultured pericytes reduces inflammatory cytokine production including IL6, TNFalpha, and MIP2.

Conclusion

The loss of C5aR1 in Foxd1 stromal cells reduces kidney fibrosis and reduces inflammatory response of kidney pericytes. These results support the role of increased expression of pericyte C5aR1 in the pathogenesis of kidney fibrosis.

Funding

• NIDDK Support