Abstract: PO0152
PD-1 Regulates Metabolic Fitness of Tregs in Protection from Kidney Ischemia-Reperfusion Injury
Session Information
- AKI Mechanisms - 1
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Dogan, Murat, University of Virginia, Charlottesville, Virginia, United States
- Venkatadri, Rajkumar, University of Virginia, Charlottesville, Virginia, United States
- Sabapathy, Vikram, University of Virginia, Charlottesville, Virginia, United States
- Xavier, Sandhya, University of Virginia, Charlottesville, Virginia, United States
- Portilla, Didier, University of Virginia, Charlottesville, Virginia, United States
- Sharma, Rahul, University of Virginia, Charlottesville, Virginia, United States
Background
Regulatory T cells (Tregs) protect the kidney in models of ischemia reperfusion injury (IRI) induced acute kidney injury (AKI). Previous studies suggested programmed cell death protein 1 (PD-1) expression by Tregs is required for their protective function in AKI. However downstream mechanisms of PD-1 signaling in Tregs in AKI is not clear. We aimed to investigate the role of PD-1 in Tregs with respect to mitochondrial function in AKI.
Methods
We induced AKI in male C57Bl/6 mice with 26 min bilateral renal IRI. CD4+ CD25+ Tregs were isolated from PD-1+/+ and PD-1-/- Foxp3-GFP mice and then injected (100,000 cells/200ul) via tail vein into recipient mice 24h prior to ischemia reperfusion surgery. Kidney function was determined by measuring creatinine and tissue KIM-1 and NGAL mRNA expression levels. Histological damage was assessed by light microscopic analysis of H&E stained kidney sections. In different set of experiments, to understand the metabolic fitness of Tregs, we treated isolated T-cells from PD-1+/+ and PD-1-/- mice and incubated them overnight with anti-CD3-Ab to mimic antigenic stimulation or with high concentration of IL-2, which is critical for Treg survival and function. Mitochondrial membrane potential of Tregs was measured with TMRE to monitor the mitochondrial fitness. FACS-sorted Tregs from PD-1+/+ and PD-1-/- mice were also analyzed for the expression of genes involved in mitochondrial dynamics and biogenesis.
Results
In the mouse kidney IRI, PD-1-/- Tregs offered no protection from AKI. Compared to PD-1+/+, PD-1-/- Tregs had reduced mitochondrial mass and mitochondrial membrane potential. In FACS-sorted Tregs, expression of markers of mitochondrial function, antioxidant pathways as well as those for mitochondrial dynamics were remarkably attenuated in the Tregs from PD-1-/- mice as compared to PD-1+/+ mice.
Conclusion
Ability of Tregs to protect kidney from IRI-induced AKI is dependent on PD-1 expression by Tregs. Mitotracker green and TMRE experiments suggest that in the absence of PD-1, Tregs have reduced mitochondrial number and/or function. Tregs require mitochondrial fitness for their development and optimal function. Additionally, these genes may regulate cytoskeleton rearrangement and microtubule movement related to cell motility, granule release and cell division.
Funding
- NIDDK Support