Endothelial NF-κB Blockade Abrogates ANCA-Induced GN

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