Apolipoprotein-L1 G1 variant contributes to hydrocephalus but not to atherosclerosis in apolipoprotein-E knock-out...

In USA, six million individuals with Sub-Saharan ancestry carry two APOL1 high-risk variants, which increase the risk for kidney diseases. Whether APOL1 high-risk variants are independent risk factors for cardiovascular diseases is unclear and requires further investigation.

We characterized a mouse model to investigate the role of APOL1 in dyslipidemia and cardiovascular diseases. Transgenic mice carrying APOL1 (G0 and G1 variants) on bacterial artificial chromosomes (BAC/APOL1 mice) were crossed with the ApoE knock-out (ApoE-KO) atherosclerosis mouse model. The compound transgenic mice were evaluated for the impact of APOL1 on systemic phenotypes.

ApoE-KO mice carrying APOL1-G0 and APOL1-G1 did not show differences in the extent of atherosclerotic lesions or aortic calcification, as evaluated by Sudan IV staining and radiographic examination, respectively. However, ~20% of ApoE-KO; BAC/APOL1-G1 mice developed hydrocephalus and required euthanasia. The hydrocephalus was communicating and likely was due to excess cerebrospinal fluid produced by the choroid plexus, where epithelial cells expressed APOL1. Single-nuclear RNA-seq of choroid plexus identified solute transporter upregulation and mTORC2 pathway activation in APOL1-G1-expressing epithelial cells. Further, in the All of Us cohort, we found higher hydrocephalus prevalence among individuals with the APOL1-G1 variant in both recessive and dominant models, supporting the mouse findings.

While APOL1-G1 expression in ApoE-KO mice did not worsen cardiovascular disease phenotypes, we uncovered hydrocephalus as a novel APOL1 risk allele-mediated phenotype. These findings extend the spectrum of APOL1-associated pathologies.