Matricellular proteins: From cardiac homeostasis to immune regulation

Tissue repair after myocardial injury is a complex process involving changes in all aspects of the myocardial tissue, including the extracellular matrix (ECM). The ECM is composed of large structural proteins such as collagen and elastin and smaller proteins with major regulatory properties called matricellular proteins. Matricellular cell proteins exert their functions and elicit cellular responses by binding to structural proteins not limited to interactions with cell surface receptors, cytokines, or proteases. At the same time, matricellular proteins act as the "bridge" of information exchange between cells and ECM, maintaining the integrity of the cardiac structure and regulating the immune environment, which is a key factor in determining cardiac homeostasis. In this review, we present an overview of the identified matricellular proteins and summarize the current knowledge regarding their roles in maintaining cardiac homeostasis and regulating the immune system. Matricellular proteins directly regulate cardiomyocytes, vascular endothelial cells and fibroblasts, or indirectly regulate immune cells including macrophages and lymphocytes, thereby affecting the outcome of cardiovascular disease. • Matricellular proteins are non-structural extracellular macromolecules that regulate cardiac homeostasis and heart function. • Matricellular proteins have diverse immunoregulatory functions, particularly in regulating macrophages and T cells. • Studying matricellular proteins faces challenges, such as specific regulation at different stages of disease. • Matricellular proteins have various applications, including disease diagnosis and biomaterial discovery.