Abstract 557: Human S100/calgranulin Accelerates Ectopic Cardiac Calcification and Promotes Cardiac Hypertrophy in Transgenic Mice with Chronic Kidney Disease in a RAGE Dependent Manner

Abstract

Purpose Chronic kidney disease (CKD) is associated with accelerated cardiovascular disease. Elevated serum S100A12 predicts cardiovascular mortality in patients with end stage renal disease. We test the hypothesis that human S100/calgranulin transgenic mice exposed to the metabolic changes of CKD would develop accelerated cardiovascular disease. Methods A novel humanized mouse with transgenic expression of human S100/calgranulin (hBAC-S100) was generated by expression of a bacterial artificial chromosome of the human S100/calgranulin gene cluster containing genes and regulatory elements for S1008/9 and S100A12 (60kb) in C57BL6/J mice. The hBAC-S100 mice were crossed with the RAGE KO mice (same C57BL6/J strain, gift from Ann Marie Schmidt, NYU) and F4 animals were used for the experiment. CKD was induced in hBAC-S100 and wild type (WT) littermate mice with intact or lacking RAGE signaling by surgical ligation of the ureters. The heart and aorta were analyzed after 10 weeks of elevated blood urea nitrogen. Results hBAC-S100 mice express human S100A12 in circulating myeloid cells and S100A12 was present in the serum of hBAC-S100 mice (25 ng/ml serum), but was not detected in WT mice. Importantly, serum hS100A12 was increased in hBAC-S100 mice with CKD compared to sham operated hBAC-S100 mice (42±17 ng/ml and 25±7 ng/ml, p=0.04). Moreover, hBAC-S100 mice with CKD exhibited ectopic cardiac calcification in fibroblast-rich annulus of the mitral and aortic valves upon Alizarin Red staining. In vivo ECHO showed abnormal mitral valve doppler flow with reduced ratio of early (E) to atrial (A) filling in hBAC-S100 mice with CKD compared to WT-CKD mice (1.17 ±0.1 vs 1.35 ±0.1, p=0.003), indicating diastolic dysfunction. Notably, hBAC-S100 mice with CKD develop cardiac hypertrophy as evidenced by increased heart weight/ body weight ratio and elevated gene expression of hypertrophic and fibrotic markers, such as ANP, β-MHC, TGF-β, CTGF, and Col 1a1. This phenotype was not observed in hBAC-S100 mice lacking RAGE, despite exposure to the same degree of CKD. Conclusion Circulating myeloid derived human S100/calgranulin is associated with the development of ectopic cardiac calcification and cardiac hypertrophy in chronic kidney disease in a RAGE dependent manner.