Editorial on the Research TopicThe role of circulating immune mediators in the crosstalk between cells of the immune system and cardiovascular systems in CVDs Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality in developed countries (1) and encompass multiple disorders including atherosclerosis, acute myocardial infarction (AMI) and stroke. Risk factors that drive CVD development include hyperlipidemia, arterial hypertension, diabetes mellitus, age, smoking, sedentary lifestyle, stress, or their combination. Mechanistically, chronic inflammation and immune cell activation play a fundamental role in the pathogenesis and progression of CVD. Indeed, strong evidence have demonstrated a key role of soluble molecules such as pro-and antiinflammatory cytokines in the atherosclerotic plaque stability (2-4) in the myocardial dysfunctions (5, 6) and in the ischemic stroke outcome (7). Moreover, extracellular vesicles (EVs), released by several cell types, have been shown to regulate a multitude of functions in target cells, thus maintaining the cardiovascular balance or contributing to pathological changes in CVD (8-10).In the Research Topic-"The Role of Circulating Immune Mediators in the Crosstalk Between Cells of the Immune System and Cardiovascular System in CVDs", we provided a platform for exposing the main advancements in the ongoing CVD research. Six papers including both reviews and original articles are published in the volume.Among the reviews, Li et al. described the role of the endothelial glycocalyx (eGCX) in lung diseases mainly focusing on the hepatopulmonary syndrome (HPS). The eGCX is a carbohydrate-rich layer lining the vascular endothelium. It is formed by soluble plasma components, bound together either directly or via soluble proteoglycans and/or glycosaminoglycans. The composition of eGCX is dynamic due to enzymatic degradation, de novo biosynthesis of new molecules and recruitments of soluble molecules from the bloodstream (11). Moreover, new evidence supports the role of the eGCX damage and fragmentation under inflammatory conditions in the pathogenesis of Frontiers in Immunology frontiersin.org 01