The key role of NLRP3 and STING in APOL1-associated podocytopathy
Junnan Wu, … , Andreas Linkermann, Katalin Susztak
Junnan Wu, … , Andreas Linkermann, Katalin Susztak
Published October 15, 2021
Citation Information: J Clin Invest. 2021;131(20):e136329. https://doi.org/10.1172/JCI136329.
View: Text | PDF
Research Article Cell biology Nephrology

The key role of NLRP3 and STING in APOL1-associated podocytopathy

Abstract

Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain–containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria.

Authors

Junnan Wu, Archana Raman, Nathan J. Coffey, Xin Sheng, Joseph Wahba, Matthew J. Seasock, Ziyuan Ma, Pazit Beckerman, Dorottya Laczkó, Matthew B. Palmer, Jeffrey B. Kopp, Jay J. Kuo, Steven S. Pullen, Carine M. Boustany-Kari, Andreas Linkermann, Katalin Susztak

×

Figure 4

Genetic deletion of Nlrp3 in G2APOL1-transgenic mice markedly improves kidney function.

Options: View larger image (or click on image) Download as PowerPoint
Genetic deletion of Nlrp3 in G2APOL1-transgenic mice markedly improves k...
(A) Experimental design for the generation of G2APOL1/Nlpr3-KO mice. (B) Representative images of APOL1 in situ hybridization. (C) Relative APOL1 transcript levels in kidneys of G2APOL1/Nlrp3-WT (n = 6) and G2APOL1/Nlrp3-KO (n = 5) mice. (D) ACR of G2APOL1/Nlpr3-KO (n = 6) and G2APOL1/Nlrp3-KO mice (n = 5) at baseline, 1, 2, and 3 weeks on doxycycline diet. ##P < 0.01 vs. baseline; *P < 0.05, **P < 0.01 vs. G2APOL1/Nlrp3-KO mice at the same time points. (E) BUN and (F) serum creatinine levels of control (n = 3), G2APOL1/Nlrp3-WT (n = 6), and G2APOL1/Nlrp3-KO mice (n = 5). *P < 0.05 vs. G2APOL1/Nlrp3-WT; #P < 0.05, ##P < 0.01 vs. control. (G) Western blots of whole-kidney lysates. (H) Relative transcript levels of Nlrp3, Casp1, Il1b, and Il6 in control (n = 7), G2APOL1/ Nlrp3-WT (n = 6), and G2APOL1/Nlrp3-KO (n = 5) mice. #P < 0.05 vs. control; *P < 0.05 vs. G2APOL1/Nlrp3-WT. (I) PAS-stained kidney sections. (J) Semiquantitative analysis of percentage of globally sclerotic glomeruli in G2APOL1/Nlrp3-WT (n = 3) and G2APOL1/NLRP3-KO (n = 5) mice. **P < 0.01 vs. G2APOL1/NLRP3-WT. (K) Representative images of glomeruli. (L) Percentage of attenuated epithelium with casts in G2APOL1/Nlrp3-WT (n = 3) and G2APOL1/NLRP3-KO (n = 5) mice. ***P < 0.001 vs. G2APOL1/NLRP3-WT. (M) Sirius red–stained kidney sections. (N) Quantification of Sirius red–positive area. ###P < 0.001 vs. control; ***P < 0.001 vs. G2APOL1/NLRP3-WT. (O) Relative mRNA levels of Col1a1, Col3a1, Fn1, and Vim in the kidneys of control (n = 3), G2APOL1/NLRP3-WT (n = 5), and G2APOL1/NLRP3-KO (n = 7) mice. ##P < 0.01, ###P < 0.001 vs. control; **P < 0.01, ***P < 0.001 vs. G2APOL1/NLRP3-WT. Scale bars: 30 μm. Significance was determined by 1-way ANOVA and SNK post hoc test. Data are expressed as the mean ± SEM.