Monocytes in heart failure: relationship to a deteriorating immune overreaction or a desperate attempt for tissue repair?

Monocytes play an important role in immune defence, inflammation, and tissue remodelling. Nevertheless, the role of monocytes in cardiovascular disease is obscure. Indeed, monocytes infiltrate dysfunctional tissue and augment tissue damage and are actively involved in tissue regeneration and healing. In support of the latter, recent studies have provided data on the functional and structural plasticity of monocytes. Monocytes are also actively involved in processes associated with tissue regeneration such as angiogenesis and vasculogenesis, either by producing pro-angiogenic factors or even by evolving to structural components of the vascular wall. This review article provides an overview on whether monocytes represent deteriorating immune overreaction in heart failure (HF), or a desperate attempt for tissue repair or physiological compensation in the failing heart. Perhaps, it is time to reconsider our attitude towards monocytes and consider more 'monocyte activation' rather than 'monocyte suppression' as a potential therapeutic target in HF.