RNA sequencing of isolated cell populations expressing human APOL1 G2 risk variant reveals molecular correlates of sickle cell nephropathy in zebrafish podocytes

APOL1 promotes endothelial cell activation beyond the glomerulus

Apolipoprotein L1 (APOL1) high-risk genotypes are associated with increased risk of chronic kidney disease (CKD) in people of West African ancestry. Given the importance of endothelial cells (ECs) in CKD, we hypothesized that APOL1 high-risk genotypes may contribute to disease via EC-intrinsic activation and dysfunction. Single cell RNA sequencing (scRNA-seq) analysis of the Kidney Precision Medicine Project dataset revealed APOL1 expression in ECs from various renal vascular compartments. Utilizing two public transcriptomic datasets of kidney tissue from African Americans with CKD and a dataset of APOL1-expressing transgenic mice, we identified an EC activation signature; specifically, increased intercellular adhesion molecule 1 (ICAM-1) expression and enrichment in leukocyte migration pathways. In vitro, APOL1 expression in ECs derived from genetically modified human induced pluripotent stem cells and glomerular ECs triggered changes in ICAM-1 and platelet endothelial cell adhesion molecule 1 (PECAM-1) leading to an increase in monocyte attachment. Overall, our data suggest the involvement of APOL1 as an inducer of EC activation in multiple renal vascular beds with potential effects beyond the glomerular vasculature.

Lessons From APOL1 Animal Models

African-Americans have a three-fold higher rate of chronic kidney disease compared to European-Americans. Much of this excess risk is attributed to genetic variants in APOL1, encoding apolipoprotein L1, that are present only in individuals with sub-Saharan ancestry. Although 10 years have passed since the discovery of APOL1 renal risk variants, the mechanisms by which APOL1 risk allele gene products damage glomerular cells remain incompletely understood. Many mechanisms have been reported in cell culture models, but few have been demonstrated to be active in transgenic models. In this narrative review, we will review existing APOL1 transgenic models, from flies to fish to mice; discuss findings and limitations from studies; and consider future research directions.

Non-invasive urinary biomarkers of renal function in sickle cell disease: an overview

Sickle cell disease (SCD) is a hereditary condition characterized by homozygosis of the hemoglobin S (HbS) gene. Marked morbimortality is observed due to chronic hemolysis, endothelial injury, and episodes of vaso-occlusion, which leads to multi-organ damage. Renal impairment is common and may have different presentations, such as deficiency in urinary acidification or concentration, glomerulopathies, proteinuria, and hematuria, frequently resulting in end-stage renal disease (ESRD). Novel biomarkers of renal function, such as kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein 1 (MCP-1) are being studied in order to enable early diagnosis of kidney damage in SCD.