ST2 and Adrenomedullin in Heart Failure

Novel insights into peptide amidation and amidating activity in the human circulation

C-terminal α-amidation is the final and essential step in the biosynthesis of several peptide hormones. Peptidylglycine α-amidating monooxygenase (PAM) is the only known enzyme to catalyse this reaction. PAM amidating activity (AMA) is known to be present in human circulation, but its physiological role and significance as a clinical biomarker remains unclear. We developed a PAM-specific amidation assay that utilizes the naturally occurring substrate Adrenomedullin-Gly (ADM-Gly, 1-53). Using our amidation assay we quantified serum amidating activities in a large population-based cohort of more than 4900 individuals. A correlation of serum amidating activity with several clinical parameters including high blood pressure was observed. Increasing PAM-AMA was an independent predictor of hard outcomes related to hemodynamic stress such as cardiovascular mortality, atrial fibrillation and heart failure during long-term follow-up (8.8 ± 2.5 years). Moreover, results from an animal study in rats utilizing recombinant human PAM provide novel insights into the physiological role of circulating PAM and show its potential significance in circulating peptide amidation.

Interleukin-1 Blockade in Cardiovascular Diseases: From Bench to Bedside

Interleukin-1 (IL-1) is the prototypical pro-inflammatory cytokine that occupies an apical place in the inflammatory cascade and also modulates cardiac function, functioning as a soluble cardiodepressant factor. Preclinical research over the past 4 decades has shown that blocking IL-1 processing or activity favorably affects cardiomyocyte survival and cardiac function in experimental animal models, paving the way for clinical studies in patients with heart disease. The promising results of phase II clinical trials of IL-1 blockade in patients with acute myocardial infarction and heart failure have been followed by a successful phase III trial in patients with prior acute myocardial infarction. Three IL-1 blockers with different mechanism of action are currently available for clinical use, although currently none have an indication for heart disease. We herein review the bench-to-bedside clinical translation of IL-1 targeting strategies and discuss the potential use of IL-1 blockade in patients with heart disease.

ST2: a novel biomarker for heart failure

ST2, an IL-1 receptor family member with transmembrane (ST2L) and soluble (sST2) isoforms, was originally described in the context of inflammatory and autoimmune diseases. However, after the identification of IL-33 as the functional ligand for ST2, and conceptualization of the role of ST2/IL-33 signaling in cardiac remodeling, sST2 has emerged as a novel cardiovascular biomarker for the presence of ventricular biomechanical overload. Concentrations of sST2 have been implicated in the presence and severity of heart failure with particular value for prognostication. We will review the use of sST2 as a prognostic marker in heart failure, including present and future directions in this exciting area.