Innovations thérapeutiques dans l’ostéoporose (anticorps antisclérostine et denosumab)

Changing concept in treatment of asymptomatic severe aortic stenosis and normal ejection fraction: time for biomarkers reappraisal

The uncertainty of whether/how to treat asymptomatic patients with isolated severe aortic stenosis and normal left ventricular ejection fraction is one of the most topical in cardiovascular medicine. Recently, the AVATAR trial: first ever randomized trial in the setting of aortic stenosis has been started in an attempt to adequately address this 'burning issue'. In light of this fact it is important to identify biomarkers which might help in risk stratification of these patients, not only in the referring physician's office during a routine exam, but also for preoperative patients scheduled for surgical replacement/transcatheter aortic valve implantation. This report is focusing on novel laboratory parameters which might be helpful in this risk stratification.

Serum and tissue biomarkers in aortic stenosis

Background: Calcific aortic valve stenosis (CAVS) is seen in a large proportion of individuals over 60 years. It is an active process, influenced by lipid accumulation, mechanical stress, inflammation, and abnormal extracellular matrix turnover. Various biomarkers (BMs) are studied, as regards mechanisms, diagnosis and prognosis. Methods: In the calcified valves calcium deposition, elastin fragmentation and disorganization of cellular matrix were assessed, together with expression of OPN, OPG, osteocalcin (OCN) and RL2.

We prospectively studied the following serum BMs in 60 patients with CAVS and compared them to 20 healthy controls, free from any cardiac disease: Matrix metalloproteinases (MMP) 2 and 9 and tissue inhibitor of metalloproteinase 1 (TIMP1), which regulate collagen turnover, inflammatory factors, i.e. tumor necrosis factor a (TNFa), interleukin 2 (IL2), transforming growth factor β1 (TGF-β1) which regulates fibrosis, fetuin-A (fet-A), osteopontin (OPN), osteoprotegerin (OPG), sclerostin (SOST), and relaxin-2 (RL2) which positively or negatively regulate calcification. Monocyte chemoattractant protein 1 (MCP-1) which regulates migration and infiltration of monocytes/macrophages was also studied as well as malondialdehyde (MDA) an oxidative marker. Results: Extent of tissue valve calcification (Alizarin Red stain) was negatively correlated with tissue elastin, and RL2, and positively correlated with tissue OCN and serum TIMP1 and MCP-1 and negatively with MMP9.

Tissue OCN was positively correlated with OPN and negatively with the elastin. Tissue OPN was negatively correlated with elastin and OPG. Tissue OPN OPG and RL2 were not correlated with serum levels In the serum we found in patients statistically lower TIMP1, fet-A and RL2 levels, while all other BMs were higher compared to the healthy group. Positive correlations between SOST and IL2, OPG and MDA but negative with TNFa and OPN were found; also MMP9 was negatively correlated with TNFa and MCP-1 was negatively correlated with TIMP1. Conclusion: We found that many BMs expressing calcification, collagen breakdown, or formation, and inflammation are increased in the valve tissue and in the serum of patients with CAVS as compared with healthy group. Our findings may give new insights towards diagnosis but also therapy. Thus antisclerostin, and antiflammatory agents could be tried for preventing aortic calcification progression.