Atherosclerotic inflammation triggers osteogenic bone transformation in calcified and stenotic human aortic valves: Still a matter of debate

Abstract

Sclerotic calcification of the aortic valve is a common disease in advanced age. However, pathophysiologic processes leading to valve calcifications are poorly understood. Transformation of atherosclerotic triggers to osteogenic differentiation is controversially discussed and is thought as a trigger of bone transformation in end stage disease. This study focuses on the transcriptional gene-profiling of severe calcified stenotic human aortic valves to clarify the molecular basis of the pathophysiological process. We collected severely calcified and stenotic human aortic valves (CSAV) with (CSAV+, n = 10) and without (CSAV−, n = 10) at least 4 weeks of statin pre-treatment prior to valve replacement and investigated transcriptional steady-state gene-profiling by using micro array technique and GAPDH-adjusted PCR for confirmation. Results were compared with findings in non-sclerotic aortic valves: C ( n = 6). Various parameters of inflammation were significantly up regulated as compared to C: eotaxin3, monokine induced by γ-interferon, vascular adhesion protein-1 (VAP-1), peroxisome proliferative activated receptor-α or transforming growth factorβ1 (TGFβ1). Except for TGFβ1 and VAP-1, statin pre-treatment neutralized altered gene expression. Genes of osteogenic bone transformation ( tenascin C, bone sialoprotein, Cbfa1, Osteocalcin, Beta-catenin, Sox- and Cyclin-genes) were found unaltered in their expression in both, CSAV− or CSAV+ in comparison to C. This study shows continuing atherosclerotic inflammation on CSAV. Additionally, no evidence of initiated osteoblastic differentiation process was found. Pre-treatment of patients with statins partially neutralized the gene pattern of inflammation on the aortic valves. This suggests that there are potent benefits of statins on early development of inflammation on calcified aortic valves.