Phenotypic and Functional Heterogeneity of Monocyte Subsets in Chronic Heart Failure Patients

SIMPLE SUMMARY: A long-term condition known as chronic heart failure (CHF) is an ongoing difficulty of the heart in pumping blood enriched in oxygen and required nutrients around the body’s tissues. CHF pathogenesis is associated with various causes, and inflammation is one of the most important factors promoting the condition. In addition, monocytes, a group of cells present in the blood and infiltrating tissues, are known to participate in both pro- and anti-inflammatory processes and thus affect myocardial remodeling over time. The aim of this work was to review current studies on the function of monocyte subsets in different types of CHF with preserved and reduced left ventricle ejection fractions and to discuss the relationship of monocyte subsets to inflammatory markers. It is expected that a deeper view into CHF pathogenesis could stimulate the search for and development of individualized therapies. ABSTRACT: Chronic heart failure (CHF) results when the heart cannot consistently supply the body’s tissues with oxygen and required nutrients. CHF can be categorized as heart failure (HF) with preserved ejection fraction (HFpEF) or HF with reduced ejection fraction (HFrEF). There are different causes and mechanisms underlying HF pathogenesis; however, inflammation can be regarded as one of the factors that promotes both HFrEF and HFpEF. Monocytes, a subgroup of leukocytes, are known to be cellular mediators in response to cardiovascular injury and are closely related to inflammatory reactions. These cells are a vital component of the immune system and are the source of macrophages, which participate in cardiac tissue repair after injury. However, these monocytes are not as homogenous as thought and can present different functions under different cardiovascular disease conditions. In addition, there is still an open question regarding whether the functions of monocytes and macrophages should be regarded as causes or consequences in CHF development. Therefore, the aim of this work was to summarize current studies on the functions of various monocyte subsets in CHF with a focus on the role of a certain monocyte subset in HFpEF and HFrEF patients, as well as the subsets’ relationship to inflammatory markers.