Abstract 13219: Dll4-Notch Signaling Mediates Vascular Inflammation and Calcification in Chronic Kidney Disease: A Novel Mechanism

Abstract

Background: Chronic kidney disease (CKD) increases cardiovascular risk. However, the underlying mechanisms remain obscure and current therapies, including statins, cannot prevent CKD-associated cardiovascular events. We previously demonstrated that the Notch signaling ligand Delta-like 4 (Dll4) promotes macrophage activation. To identify a new mechanism and therapeutic target, we investigated the causal role of the Dll4-Notch pathway in vascular inflammation in CKD. Methods & Results: [In vitro] Indoxyl sulfate, a major uremic toxin, is an independent risk predictor in CKD. Clinically relevant concentrations (0.5-1.0 mM) of indoxyl sulfate increased the expression of proinflammatory molecules (e.g., IL-1β, TNFα, MCP-1), and Notch signaling components (e.g., Dll4, Notch3) in human primary macrophages derived from peripheral blood mononuclear cells. Notch inhibition with the γ-Secretase inhibitor DAPT suppressed indoxyl sulfate-triggered induction of proinflammatory molecules (e.g., MCP-1, Figure A) in macrophages. [In vivo] In LDL receptor-deficient (Ldlr-/-) mice, an established model of atherosclerosis, 5/6 nephrectomy induced renal dysfunction assessed by elevated creatinine (0.56 ± 0.05 mg/dl) and BUN (128.0 ± 1.9 mg/dl), CKD accelerated the expression of IL-1β, IL-6, TNFα, and MCP-1 in splenic macrophages, and aortic atherosclerosis and calcification in Ldlr-/- mice Suppression of Notch signaling by Dll4 antibody reduced the size of atherosclerotic lesions of the aorta (p<0.05) and luminal stenosis in the brachiocephalic arteries (p<0.05) in the CKD cohort as compared to mice treated by control IgG (n=14/13 per group). Dll4 antibody also decreased macrophage accumulation and early calcification (alkaline phosphatase activity) in the aorta (Figure B). Conclusion: The present study suggests that Dll4 serves as a new therapeutic target for atherosclerotic plaque inflammation and calcification in CKD.