Abstract
Macrophages play a pivotal role in myocardial remodeling (MR) process which could eventually lead to heart failure. Splenic monocytes could be mobilized and recruited under inflammatory conditions and differentiated into different types of macrophages in heart tissues. Inflammatory M1 macrophages could aggravate tissue damage whereas M2 macrophages could promote angiogenesis and tissue repair process. Unbalanced ratio of M1/M2 macrophages may eventually lead to adverse remodeling. Therefore, regulating differentiation and activities of macrophages are potential strategies for the management of myocardial remodeling. Qishen Granule (QSG) is an effective Chinese medicine for treating heart failure. Our previous studies demonstrated that QSG could inhibit myocardial fibrosis through regulating secretion of cytokines and activation of macrophages. However, the detailed effects of QSG on had not been elucidated yet. In this study, we aimed to explore the effect of QSG on the release of splenic monocytes, the recruitment of monocytes into heart tissues and the differentiation of macrophages under ischemic conditions. Our results showed that QSG could suppress the release of monocytes from the spleen and recruitment of monocytes to heart tissues via inhibiting splenic angiotensin (Ang) II/AT1-cardiac monocyte chemotactic protein (MCP)-1/CC chemokine receptor 2 (CCR2) pathway. The anti-fibrotic effect of QSG was exerted by inhibiting M1 macrophage-activated transforming growth factor (TGF)-β1/Smad3 pathway. Meanwhile, QSG could promote angiogenesis by promoting differentiation of M1 macrophages into M2 macrophages. Our results suggest that compounds of Chinese medicine have synergistic effects on cardiac and splenic organs through regulating differentiation of monocytes/macrophages in inhibiting myocardial remodeling.
Highlights
Myocardial remodeling (MR) is an important pathophysiological change after myocardial infarction, and is a common pathological change during the development of heart failure (HF) (Pryds et al, 2019)
HE staining showed that the number of monocytes in the marginal zone of the spleen was decreased after Left anterior descending (LAD) ligation compared with the sham group, indicating that after LAD ligation, spleen released a large number of monocytes
Treatment of Qishen Granule (QSG) and fosinopril could significantly down-regulate the levels of AngII, AT1 and monocyte chemotactic protein-1 (MCP-1), indicating that QSG could suppress the release of monocytes from the spleen via inhibiting Ang angiotensin II (II)/ AT1 signaling pathway (Figures 1B, C)
Summary
Myocardial remodeling (MR) is an important pathophysiological change after myocardial infarction, and is a common pathological change during the development of heart failure (HF) (Pryds et al, 2019). Macrophages participate in the healing process after myocardial infarction. Macrophages are involved in myocardial injury, repair and remodeling processes during the inflammatory response (Hulsmans et al, 2018). It is speculated that these resident macrophages may play roles in guarding against infection, regulating angiogenesis and directing matrix turnover (Jablonski et al, 2015). Under inflammatory condition, such as myocardial infarction, circulating monocytes will be abundantly recruited to ischemic heart tissues through monocyte chemotactic protein-1 (MCP-1)/CC chemokine receptor 2 (CCR2) interactions. Monocytes can differentiate into different types of macrophages which participate either in inflammatory or repairing process. The dynamic regulation and balance between M1 and M2 macrophages will determine the ventricular remodeling process
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