Levels of MCP-1 and GM-CSF mRNA correlated with inflammatory cytokines mRNA levels in experimental autoimmune myocarditis in rats.

Infiltration of monocytes and T cells is known to be an essential trigger for the progression of experimental autoimmune myocarditis (EAM) in rats. Monocyte chemotactic protein-1 (MCP-1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were shown to mediate the migration of monocytes and T cells into inflammatory sites and to proliferate monocytes. Thus, we evaluated levels of MCP-1 and GM-CSF mRNA in the myocardium of EAM in rats using a real time quantitative PCR method. We also examined the correlation of MCP-1 or GM-CSF mRNA levels with those of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in the same lesion. Levels of MCP-1, GM-CSF, TNF-alpha, IL-1beta and IL-6 mRNA increased with the progression of myocarditis which was accompanied by the accumulation of ED-1 positive cells. The MCP-1 and GM-CSF mRNA levels were positively correlated with TNF-alpha, IL-1beta and IL-6 mRNA levels in the same lesion of EAM. We also demonstrated that serum MCP-1 concentrations were increased during the active stage of EAM, and were correlated with MCP-1 mRNA levels in the myocardium of each rat. These findings suggest that elevated MCP-1 and GM-CSF may associate with the migration and proliferation of monocytes/macrophages in EAM. Thus, MCP-1 and GM-CSF may play an important role in the progression of EAM.