Abstract 061: Renal A20 Protects Against The Cisplatin-induced Kidney Injury

Abstract

We recently reported that the ubiquitin-editing protein A20 in myeloid cells can limit the severity of hypertension. However, whether A20 in the kidney regulates renal injury without impacting systemic immune responses remains unclear. To address this question, we bred A20 flox/flox mice with the Pax8-rtTA and Tet-On lines, generating inducible renal epithelial cell A20 knockout mice (A20 iKKO). Mice with all 3 transgenes were used as the A20 iKKO group, whereas mice lacking the Pax8-rtTA or Tet-On transgene were wild-type (WT) controls. Before the experiments, mice were given 2mg/ml of doxycycline in water containing 5% (5 of 100) sucrose for 2 weeks so that A20 in renal tubular cells was ablated. 3 days after a single dose of cisplatin (20mg/kg), A20 iKKO mice exhibited more severe kidney injury compared to WTs (blinded injury score, 3.2±0.41 vs. 2.1±0.35 au, p=0.039). A20 iKKOs also had upregulated renal mRNA levels for NGAL (6.0±1.91 vs. 1.0±0.18 au, p=0.018) and KIM-1(3.3±1.2 vs. 1.0±0.29 au, p=0.07). Injured kidneys from the A20 iKKOs contained greater absolute numbers of T cells (123.6±8.5 vs. 53.8±4.7, x10 4 cells per gram kidney, p<0.001), macrophages (159.7±22.5 vs. 52.7±9.9, x10 4 cells per gram kidney, p<0.001), and dendritic cells (66.7±10.6 vs. 32.6±6.1, x10 4 cells per gram kidney, p=0.015) than WTs by flow cytometric analysis. In turn, mRNA levels for TNF-α (9.1±2.62 vs. 1.0±0.18 au; p=0.006) and IL-1β (4.1±1.06 vs. 1.0±0.13 au; p=0.009) were increased in the injured A20 iKKO injured kidneys vs WTs. Thus, A20 in the kidney epithelium protects against cisplatin-induced kidney injury by constraining renal immune cell accumulation and inflammatory cytokine release.