Effect of interleukin-6 on myocardial regeneration in mice after cardiac injury

Our aim was to investigate the role of interleukin-6 (IL-6) in myocardial regeneration from mice after cardiac injury. The newborn mice were divided into the following 4 groups (16 in each group): sham group, model group, IL-6-/- group (IL-6 knockout) and IL-6 group (IL-6 overexpression). Electrocardiography was performed on all mice and found higher LVEDD, LVESD and IVST and lower LVEF and LVFS in the IL-6 group compared with the sham group. Using HE staining, severe myocardial injury combined with infarction and fibrosis were observed in the IL-6-/- group, while the damaged myocardial tissue was repaired to some extent in the IL-6 group. The expression of IL-6 in the IL-6 group were significantly up-regulated. BrdU immunofluorescence found that the IL-6-/- group had the least number of BrdU positive cells, while the IL-6 group had more BrdU positive cells than the model group and the IL-6-/- group. Expressions of IL-6, cyclinD1 and Bcl-2 in the IL-6 group were up-regulated compared with other groups. In conclusion, IL-6 overexpression could enhance cardiomyocyte proliferation and relevant protein expression in mice myocardium, thus promoting cardiac regeneration.