Pharmacological Inhibition of CCR2 Signaling Exacerbates Exercise-Induced Inflammation Independently of Neutrophil Infiltration and Oxidative Stress

Although exercise-induced humoral factors known as exerkines benefit systemic health, the role of most exerkines has not been investigated. Monocyte chemoattractant protein-1 (MCP-1) is a representative chemokine whose circulating concentrations increase after exercise, and it is one of the exerkines. MCP-1 is a ligand for CC chemokine receptor 2 (CCR2), which is expressed on monocytes, macrophages, and muscle cells. However, there is no information on the role of CCR2 signaling in exercise. Therefore, to investigate the research question, we administrated CCR2 antagonist or PBS to mice to inhibit CCR2 signaling before and after exercise. Our results showed that CCR2 signaling inhibition promoted exercise-induced macrophage infiltration and inflammation 24 h after exercise in muscle. CCR2 signaling inhibition also exacerbated exercise-induced inflammation immediately after exercise in muscle. However, neutrophil infiltration and oxidative stress had no contribution to exercise-induced inflammation by CCR2 signaling inhibition. CCR2 signaling inhibition also exacerbated exercise-induced inflammation immediately after exercise in kidney, liver, and adipose tissues. To summarize, pharmacological inhibition of CCR2 signaling exacerbated exercise-induced inflammation independently of neutrophil infiltration and oxidative stress.