Abstract: SA-PO789
APOL1 Risk Variants Induce Mitochondrial Dysfunction in Patient-Derived Kidney Organoids
Session Information
- Genetic Diseases: Glomerulopathies - II
November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1202 Genetic Diseases of the Kidneys: Non-Cystic
Authors
- Song, Heein, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Dumas, Sébastien J., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Ma, Lijun, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
- Wang, Gangqi, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Witjas, Franca, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Van den Berg, Cathelijne W., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Rocco, Michael V., Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
- Freedman, Barry I., Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
- Rabelink, Ton J., Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Spijker, Siebe, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
Background
Apolipoprotein L1 (APOL1) high-risk genotypes cause CKD in the presence of interferon gamma (IFN-γ). To elucidate mechanisms, patient-derived induced pluripotent stem cells (iPSCs) were used to generate a kidney organoid model of APOL1 nephropathy.
Methods
iPSCs were generated from fibroblasts of two patients with APOL1 nephropathy homozygous for G1G1 and G2G2 risk variants (RV). Isogenic control of the G2G2 patient iPSCs was created with CRISPR-Cas9 gene editing. Kidney organoids were generated using G1G1, G2G2 and isogenic control iPSCs. Organoids were treated with IFN-γ and analyzed by single cell transcriptomics, immunofluorescence imaging and mitochondrial respiration assay.
Results
APOL1 gene expression was upregulated in all genotypes following IFN-γ. Single cell transcriptomics of organoids 3 days post IFN-γ treatment showed APOL1 induction was mainly in podocytes, confirmed with colocalized immunolabeling of APOL1 and podocalyxin. RV podocytes showed significantly decreased expression of nuclear DNA-encoded OXPHOS related genes, while mitochondrial DNA-encoded gene expressions were increased. Further, a novel subpopulation in RV podocytes was identified, characterized by a metabolic switch to glycolysis. Next, glomeruli were isolated from RV and isogenic control organoids to assess oxygen consumption rate and reactive oxygen species (ROS). In RV glomeruli, maximal respiration rate upon IFN-γ treatment did not increase, unlike in the isogenic control, and ROS levels were 30% higher.
Conclusion
We generated a kidney organoid model of APOL1 nephropathy using patient-derived RV and isogenic control iPSCs. Exposure of APOL1 RV organoids to IFN-γ induced podocyte mitochondrial dysfunction and may provide a mechanism for development of CKD. This model supports further research in mechanisms and potential therapeutics for APOL1 nephropathy.
APOL1 expression increased upon IFN-γ treatment (A), specifically in the podocyte population (B).