MI was induced in male Sprague Dawley rats by coronary artery ligation. Controls were sham-operated (Sh) or non-operated (C). Blood and samples from the left ventricle (LV) were collected at weeks 1 and 4 post-MI. At week 1, MI animals exhibited increased IL-6, IL-23 and TGF-β mRNA levels with no apparent change in IL-17 mRNA or protein levels in whole LV. Only TGF-β mRNA remained elevated at week 4 post-MI. However, further analysis revealed that IL-17A mRNA and protein levels as well as IL-6 and IL-23 mRNA were indeed increased in the infarcted region, though not in the remote non infarcted region of the LV, except for IL-23 mRNA.
The increased expression of IL-17A and Th17-related cytokines in the infarcted region of LV, suggests that this proinflammatory pathway might play a role in early stages of post MI cardiac remodelling.