ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

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

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: PO0424

TGF-βR1-Mediated Tubular Injury and Cell Death Requires Recruitment of Inflammatory Cells via CCL5

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Lassen, Emelie, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Yu, Liping, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Stadler, Krisztian, Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States
  • Daehn, Ilse S., Icahn School of Medicine at Mount Sinai, New York, New York, United States
Background

Activation of the TGFβ signaling pathway plays an important role in both AKI and CKD pathogenesis. We have previously shown that ligand-independent activation of TGFβR1 in proximal tubules results in rapid epithelial cell injury and death, as well as immune cell infiltration. This study aims to determine the drivers and mechanism of epithelial cell injury.

Methods

In vivo studies were performed in transgenic Pax8Tgfbr1 mice with proximal tubular activation of TGFβR1 signaling by +/- doxycycline (Dox) chow. Immortalized proximal tubular epithelial cells (PTECs) from Pax8Tgfbr1 mice were treated with Dox and with activated spleen derived leukocytes. Cell death was determined by TUNEL or AnnexinV/PI staining, lipid-derived free radicals by electron paramagnetic resonance (EPR) spin resonance spectroscopy and in vivo spin trapping, and mitochondrial superoxide was determined by mitoSOX. Gene and protein expression were determined by RT-PCR, western blotting and immunofluorescence.

Results

Canonical TGFβ signaling induced by Dox was confirmed in Pax8Tgfbr1 mice and in isolated PTECs cells by increased Tgfbr1 gene expression and phospho-SMAD2 or nuclear translocation of SMAD2/3. Markers of tubular cell injury and inflammation were prominent in kidney sections from Pax8Tgfbr1 mice after 5 days of Dox. There was also increased oxidative stress and cell death after 5 days. TGFβR1 signaling activation in cultured Pax8Tgfbr1 PTECs did not induce cell death, but showed an increase in CCL5/RANTES expression, a chemokine involved in recruitment of several immune cell types, among them monocytes and T-cells. PTECs co-cultured with leukocytes isolated from spleens resulted in mitochondrial oxidative stress and cell death of PTECs. Cell death and mitochondrial oxidative stress was ameliorated by a mitochondrial superoxide scavenger in co-cultured PTECs.

Conclusion

Our studies show that induction TGFβR1 signaling in tubular epithelial cells triggers recruitment of inflammatory cells which mediate mitochondrial stress and cell death.

Funding

  • Other NIH Support