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Abstract: PO1329

Uncovering Mechanisms of Risk-Variant APOL1-Modulated Inflammatory Signaling in Macrophages

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Liu, Esther, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
  • Lin, Jennie, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
Background

In the United States, Black Americans face a higher risk to develop CKD and progress to end stage kidney disease (ESKD) even after accounting for clinical and socioeconomic factors. Variants in the gene encoding for innate immunity factor Apolipoprotein L1 (APOL1) have been identified as risk factors for focal segmental glomerulosclerosis (FSGS) and HIV-associated nephropathy (HIVAN) in individuals with recent African ancestry. However, the role of immune cells in APOL1 nephropathy is not well understood. In this study we seek to understand the effect of risk variant APOL1 on macrophage function and inflammation.

Methods

Isogenic induced pluripotent stem cell (iPSC) lines expressing the G0, G1, and G2 variants of APOL1 were generated through CRISPR/Cas9 gene editing. These iPSC lines were used to generate iPSC-derived macrophages (IPSDM). Peritoneal and bone marrow-derived macrophages (BMDMs) were collected from transgenic mice 14-18 weeks of age expressing G0, G1, and G2 variants of APOL1. Expression of APOL1 in cultured iPSDMs, peritoneal macrophages, and BMDMs was induced with IFNγ (5 ng/mL).

Results

We observed that risk-variant APOL1 expression results in higher TNF and IL1B gene expression by nine-fold and two-fold respectively, in G1 iPSDM (P < 0.05). In APOL1 transgenic mouse peritoneal macrophages, oil red O staining revealed 2.83-fold increased neutral lipid accumulation (N = 3, P < 0.01) and 4.84-fold decreased efferocytosis capacity measured with flow cytometry (N = 5, P < 0.05) in G1 and G2 mice compared to G0. qRT-PCR analysis showed glycolysis genes to be increased in G1 iPSDM compared to G0. Additionally, G2 mouse BMDMs exhibit increased glycolytic rate compared to G0 both at baseline and under mitochondrial stress when APOL1 was induced with IFNγ.

Conclusion

The findings in this study unveil some mechanisms by which risk-variant APOL1 modulates macrophage inflammatory phenotype and function, relevant to kidney disease progression.

Funding

  • Private Foundation Support