ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on X

Kidney Week

Abstract: TH-PO763

Soluble CD93 Contributes to Podocyte Activation in Minimal Change Disease

Session Information

Category: Glomerular Diseases

  • 1403 Podocyte Biology

Authors

  • Bauer, Colin D., Children's Hospital Colorado, Aurora, Colorado, United States
  • Piani, Federica, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
  • Lanaspa, Miguel A., University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
  • Andres-Hernando, Ana, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
  • Bjornstad, Petter, Children's Hospital Colorado, Aurora, Colorado, United States
  • Kaneko, Kazunari, Kansai Daigaku, Suita, Osaka, Japan
  • Thurman, Joshua M., University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
  • Johnson, Richard J., University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
  • Cara-Fuentes, Gabriel M., Children's Hospital Colorado, Aurora, Colorado, United States
Background

Minimal Change Disease (MCD) is considered a podocytopathy, but subtle endothelial injury may also be present. CD93, a protein primarily expressed in endothelium, mediates focal adhesion kinase (FAK) activation in endothelium and can be shed during inflammation. We tested the hypothesis that glomerular endothelium releases CD93 that in turn activates podocyte FAK in MCD.

Methods

We tested for CD93 in human kidney tissue (immunofluorescence), urine and sera (ELISA) from 27, 57 and 48 children, respectively, with MCD during relapse. Patients without glomerular disease served as controls (n=9 for kidney tissue, n=19 for soluble CD93). We cultured human glomerular endothelial cells (GEnC) with human sera and measured CD93 (extracellular domain) in cell lysates by western blot. Additionally, we exposed GEnC to human sera and, following washing steps, we measured CD93 (ELISA) in serum-free supernatants. By co-immunoprecipitation, we studied CD93 and podocyte β1 integrin interaction. Human podocytes were also treated with recombinant CD93 (rCD93) and human sera, with β1 integrin (Mab13) and CD93 blocking antibodies, respectively, and we assessed FAK activation by western blotting.

Results

Compared to controls, CD93 expression was higher in MCD glomeruli and colocalized with endothelium (p<0.0001). Soluble CD93 was higher in urine (~10 fold) and serum (~1.5 fold) from MCD patients in relapse compared to controls (p<0.0001 for both). MCD sera in relapse stimulated cultured human GEnC to release CD93. CD93 was higher in supernatants and lower in cell lysates from GEnC previously exposed to MCD sera in relapse compared to controls (p<0.01). rCD93 bound to podocyte β1 and medaited FAK activation (Figure 1a, p<0.05 at 6 hours). MCD sera in relapse caused podocyte FAK activation, which was mitigated by adding a CD93 antibody to sera (Figure 1b, p=0.01).

Conclusion

MCD sera trigger the release of soluble CD93 from GEnC and this, in turn, contributes to podocyte activation.

Funding

  • Private Foundation Support