Mann, Morgan

Ischemic cardiomyopathy (ICM) is a leading cause of heart failure characterized by extensive remodeling of the cardiac extracellular matrix (ECM). While initially adaptive, ECM deposition following ischemic injury eventually turns maladaptive, promoting adverse cardiac remodeling. The strong link between the extent of fibrosis and adverse clinical outcomes has led to growing interest in ECM-targeted therapies to prevent or reverse maladaptive cardiac remodeling in ICM; yet, the precise composition of the ECM in ICM remains poorly defined. In this study, we employed sequential protein extraction enabled by the photocleavable surfactant Azo to enrich ECM proteins from left ventricular tissues of patients with end-stage ICM and nonfailing donor hearts. High-resolution mass spectrometry–based quantitative proteomics identified and quantified over 6,000 unique protein groups, including 315 ECM proteins. We discovered significant upregulation of key ECM components, particularly glycoproteins, proteoglycans, collagens, and ECM regulators. Notably, LOXL1 , FBLN1 , and VCAN were among the most differentially expressed. Functional enrichment analyses revealed enhanced TGFB signaling, integrin-mediated adhesion, and complement activation in ICM tissues, suggesting a feedback loop driving continued ECM deposition in the end-stage failing heart. Together, our findings provide a comprehensive proteomic landscape of ECM alterations in the end-stage ICM myocardium and identify promising molecular targets for therapeutic intervention.

Abstract Background Protein biomarkers are routinely measured for disease diagnosis and prognosis in clinical laboratories. Since most assays focus on protein quantity, information about proteoforms is often not acquired. Proteoforms of a protein represent the complex integration of genetic polymorphism, alternative splicing of RNA transcripts, and post-translational modifications (PTMs) on the amino-acid backbone. A detailed analysis of the post-translationally modified proteoforms (PTMPs), which are influenced by pathophysiological conditions, may lead to more precise diagnosis and prognosis. Content This article first discusses the methodologies used to accurately detect and characterize PTMPs, i.e., immunoassays, electrophoresis, chromatography, and intact and proteolysis-aided mass spectrometry techniques. Then it reviews specific examples of PTMP biomarkers that have been successfully translated from biomarker discovery to clinical use. The examples include β2–transferrin for cerebrospinal fluid leak diagnosis, phosphorylated tau proteoforms for Alzheimer disease diagnosis, and fucosylated alpha-fetoprotein for hepatocellular carcinoma prognosis. In addition, the article provides prospective views of novel analytical technologies and promising new PTMP biomarkers entering clinical practice. Summary In summary, PTMs are controlled by biochemical processes to modulate the functions of proteins by expanding their chemical diversity. PTM alterations in proteins can be indicators for pathophysiological conditions. Advances in analytical technologies are deepening our understanding of PTMPs and paving the way for their translation to clinical use. As research continues to discover the clinical meaning of PTMP biomarkers, they are poised to become valuable additions to the clinical testing menu for precision medicine.

Abstract Ischemic cardiomyopathy (ICM) is a leading cause of heart failure characterized by extensive remodeling of the cardiac extracellular matrix (ECM). While initially adaptive, ECM deposition following ischemic injury eventually turns maladaptive, promoting adverse cardiac remodeling. The strong link between the extent of fibrosis and adverse clinical outcomes has led to growing interest in ECM targeted therapies to prevent or reverse maladaptive cardiac remodeling in ICM; yet, the precise composition of the ECM in ICM remains poorly defined. In this study, we employed a sequential protein extraction enabled by the photocleavable surfactant Azo to enrich ECM proteins from left ventricular tissues of patients with end-stage ICM (n=16) and nonfailing donor hearts (n=16). High-resolution mass spectrometry-based quantitative proteomics identified and quantified over 6,000 unique protein groups, including 315 ECM proteins. We discovered significant upregulation of key ECM components, particularly glycoproteins, proteoglycans, collagens, and ECM regulators. Notably, LOXL1, FBLN1, and VCAN were among the most differentially expressed. Functional enrichment analyses revealed enhanced TGFβ signaling, integrin-mediated adhesion, and complement activation in ICM tissues, suggesting a feedback loop driving continued ECM deposition in the end-stage failing heart. Together, our findings provide a comprehensive proteomic landscape of ECM alterations in the end-stage ICM myocardium and identify promising molecular targets for therapeutic intervention.