Abstract: TH-PO340

Proximal Tubule DRP1 Deletion after AKI Promotes Recovery

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

  • Perry, Heather M., University of Virginia, Charlottesville, Virginia, United States
  • Bajwa, Amandeep, University of Virginia, Charlottesville, Virginia, United States
  • Huang, Liping, University of Virginia, Charlottesville, Virginia, United States
  • Okusa, Mark D., University of Virginia, Charlottesville, Virginia, United States
Background

Mitochondrial dysfunction plays a crucial role in the pathogenesis of kidney disease. A key mediator of mitochondrial function is the GTPase, dynamin related protein 1 (DRP1). The cell specific role of DRP1 during recovery from acute kidney injury (AKI) is unknown. Proximal tubule (PT) cells are highly dependent on promoting mitochondrial function in proximal tubule cells during recovery from AKI may prevent kidney dysfunction and progressive fibrosis. Thus, we hypothesize that the spatio-temporal genetic deletion of DRP1 in proximal tubules after ischemia-reperfusion injury (IRI) promotes kidney recovery in mice.

Methods

iSLC34a1CreERT2 Drp1fl/fl (iDrp1 PTKO, n = 8) and littermate control iSLC34a1CreERT2 Drp1wt/wt (n = 5) mice were subjected to unilateral renal ischemia. Tamoxifen was initiated 3d later to induce deletion of DRP1 followed by a nephrectomy of the un-operated kidney at 13d and mice were euthanized on day 14. Plasma was collected for creatinine (PCr) measurement and kidneys were prepared for histology to assess renal injury by H&E, fibrosis by picro-sirius red and Masson’s trichrome, and detection of myofibroblasts, macrophages and endothelial rarefaction by IF. Total kidney tissue mRNA levels of fibrosis markers, SMA, Col1a1, Col3a1, Fn, and Vim were measured by RT-qPCR. Mitochondrial function was assessed by Seahorse.

Results

iDrp1 PTKO mice had attenuated IRI-induced PCr levels compared to control mice (1.10 vs. 0.21 mg/dl respectively, p < 0.05). Consistent with preserved kidney function, iDrp1 PTKO mice had attenuated renal injury compared to controls. Histological measures of fibrosis and transcript levels of fibrosis markers were also reduced in IRI kidneys of iDrp1 PTKO mice compared to controls. Hallmarks of fibrosis including myofibroblast formation, macrophage infiltration and capillary rarefaction were attenuated in IRI kidneys of iDrp1 PTKO mice compared to control mice. Lastly, primary proximal tubule cells lacking DRP1 had enhanced mitochondrial function.

Conclusion

Loss of DRP1 after IRI allows for epithelial cells to recover and prevent kidney dysfunction and progressive fibrosis. Targeting DRP1 and mitochondrial function may be an effective therapeutic strategy to allow for epithelial recovery after AKI.

Funding

  • NIDDK Support