Abstract: FR-PO315
A Novel Role of APOL1 Risk-Alleles in T-Cell Activation and Focal Segmental Glomerulosclerosis
Session Information
- Genetic Diseases: Models, Mechanisms, Treatments
November 04, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1102 Genetic Diseases of the Kidneys: Non-Cystic
Authors
- Pell, John F., Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Reghuvaran, Anand, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Nagata, Soichiro, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Banu, Khadija, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Shi, Hongmei, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Chernova, Irene, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Ishibe, Shuta, Yale University Department of Internal Medicine, New Haven, Connecticut, United States
- Menon, Madhav C., Yale University Department of Internal Medicine, New Haven, Connecticut, United States
Background
G1-, G2-variants in apolipoprotein-L1 (APOL1) increase the risk of FSGS vs. the major allele (G0). While podocyte APOL1 expression is needed for FSGS, we recently reported a provocative role for APOL1 within the immune system, as activated CD4+ and CD8+ T cells which expressed APOL1 showed more activation in G1- or G2-genotypes by single cell transcriptomics.
Methods
We studied APOL1’s immunological role using a novel BAC-transgenic mouse (BAC-Tg) for G0-, G1- or G2-APOL1 expression under the human APOL1 promoter (G0-, G1-, G2-pure), and crossed each BAC-Tg line with dox-inducible interferon γ (Ifng)-expressing mice (either Rosa-Ifng- or Nphs2-Ifng-G0,-G1, or -G2), as IFNγ regulates APOL1 expression.
Results
In splenocytes, APOL1- and dox-induced IFNγ-expression were confirmed by qPCR. FACS analysis showed that adult BAC-Tg spleens had similar proportions of major immune cell types in all variants with/without dox. The proportion of CD8+ T cells that were activated (CD44+CD8+) was significantly higher in G1 and G2 mice following dox vs. G0 [Fig.A-B]. T cell receptor stimulated G1-, G2-CD8+ T cells showed greater proliferation and marked IFNγ production vs. G0 [C-D]. In response to viral nucleic acid, G1-CD8+ T cells showed further increases in IFNγ and IL-2 intracellular staining (P<0.01 vs G0).
To test the role of APOL1-variant immune cells in FSGS, we used bone marrow transfer [E]. Rosa-Ifng-G1, -G2 mice that received Rosa-Ifng-G1-marrow developed FSGS after dox feeding (positive control). Strikingly, Ifng-G1 marrow (IFNγ induced only in donor cells) induced albuminuria in G1-, G2-pure recipients (without podocyte IFNγ excess) while Nphs2-driven IFNγ expression did not induce FSGS, suggesting FSGS was induced in variant-glomeruli by G1-marrow-derived IFNγ [F-G; n=4]. Ex vivo, primary G1-podocytes treated with supernatant from TCR-stimulated G1-CD8+ T cells showed greater apoptosis (Annexin V) vs. G0 supernatant [n=3 each; H].
Conclusion
Our data suggest a novel role for activated CD8+ T cells as a key source of IFNγ in G1- and G2 risk-genotype-Bac-Tg mice, inducing FSGS.
Funding
- Other NIH Support