APOL1 Renal Risk Variants: Fertile Soil for HIV-Associated Nephropathy

Abstract

Apolipoprotein L1 (APOL1) genetic variants are potent risk factors for glomerular disease, but one or more additional factors are required for expression of glomerular disease. Uncontrolled or poorly controlled human immunodeficiency virus (HIV) infection is the most potent susceptibility factor for APOL1 nephropathy that has been identified to date. APOL1 variants are associated with HIV-associated nephropathy (HIVAN), a podocyte disease, but not with HIV-immune complex disease, primarily a disease of the mesangium. The mechanism by which HIV brings out the latent glomerular disease risk remains to be defined. There are at least two classes of candidate mechanisms to explain the potent interaction between HIV-1 and APOL1. First, APOL1 variant proteins and HIV accessory proteins implicated in HIVAN may target the same or related intracellular pathways in podocytes. Recent data suggest roles for interleukin 1b and transcription factor EB. Second, features of uncontrolled HIV infection, including increased circulating factors such as interferon, may drive APOL1 gene transcription or act upon podocytes in other ways. Deeper probing of APOL1-HIV interactions may yield insights that will aid in understanding HIVAN, APOL1 nephropathy, and podocyte biology.

Keywords: Chronic kidney disease; Nef; Vpr; interferon.

Figure 1. Effect of APOL1 in NIH and South African cohorts

Shown are the odds ratios for APOL1 and HIVAN in South Africa. On the right are the associations with two APOL1 risk alleles. On the left are the associations with one risk APOL1 risk allele. Even with small sample size, an effect can be seen for a single copy of the G1 allele but not for the G2 allele, even though sample sizes were similar. Used with permission (Kasembeli et al. 2015).