Endothelial NF-<i>κ</i>B Blockade Abrogates ANCA-Induced GN.

Abstract

ANCA-associated vasculitis (AAV) is a highly inflammatory condition in which ANCA-activated neutrophils interact with the endothelium, resulting in necrotizing vasculitis. We tested the hypothesis that endothelial NF-<i>κ</i>B mediates necrotizing crescentic GN (NCGN) and provides a specific treatment target. Reanalysis of kidneys from previously examined murine NCGN disease models revealed NF-<i>κ</i>B activation in affected kidneys, mostly as a p50/p65 heterodimer, and increased renal expression of NF-<i>κ</i>B-dependent tumor necrosis factor <i>α</i> (TNF-<i>α</i>). NF-<i>κ</i>B activation positively correlated with crescent formation, and nuclear phospho-p65 staining showed NF-<i>κ</i>B activation within CD31-expressing endothelial cells (ECs) in affected glomeruli. Therefore, we studied the effect of ANCA on NF-<i>κ</i>B activation in neutrophil/EC cocultures <i>in vitro</i> ANCA did not activate NF-<i>κ</i>B in primed human neutrophils, but ANCA-stimulated primed neutrophils activated NF-<i>κ</i>B in ECs, at least in part <i>via</i> TNF-<i>α</i> release. This effect increased endothelial gene transcription and protein production of NF-<i>κ</i>B-regulated interleukin-8. Moreover, upregulation of endothelial NF-<i>κ</i>B promoted neutrophil adhesion to EC monolayers, an effect that was inhibited by a specific IKK<i>β</i> inhibitor. In a murine NCGN model, prophylactic application of E-selectin-targeted immunoliposomes packed with p65 siRNA to downregulate endothelial NF-<i>κ</i>B significantly reduced urine abnormalities, renal myeloid cell influx, and NCGN. Increased glomerular endothelial phospho-p65 staining in patients with AAV indicated that NF-<i>κ</i>B is activated in human NCGN also. We suggest that ANCA-stimulated neutrophils activate endothelial NF-<i>κ</i>B, which contributes to NCGN and provides a potential therapeutic target in AAV.