Decreased myocardial dendritic cells is associated with impaired reparative fibrosis and development of cardiac rupture after myocardial infarction in humans

Background-Dendritic cells (DC) play pivotal roles in regulating the immune system and inflammatory response. We previously reported DC infiltration in the infarcted heart and its immunoprotective roles in the post-infarction healing process after experimental myocardial infarction (MI). However, its clinical significance has not been determined. Methods and Results-The degree of DC infiltration and its correlation with the post-infarction healing process in the human infarcted heart were investigated in 24 autopsy subjects after ST-elevation MI. Patients were divided into two groups according to the presence (n=13) or absence (n=11) of cardiac rupture. The numbers of infiltrated DC and macrophages and the extent of fibrosis in the infarcted area were examined. In the rupture group, CD68⁺ macrophage infiltration was increased and CD209⁺ DC, and CD11c⁺ DC infiltration and the extent of reparative fibrosis were decreased compared with the non-rupture group, under matched baseline characteristics including the time from onset to death and use of revascularization. Furthermore, there was a significant positive correlation between the number of infiltrating CD209⁺ DC, and CD11c⁺ DC and the extent of reparative fibrosis. Conclusions-Decreased number of DC in human-infarcted myocardial tissue was associated with increased macrophage infiltration, impaired reparative fibrosis, and the development of cardiac rupture after MI. These findings suggest a protective role of DC in post-MI inflammation and the subsequent healing process.