Figure 5A shows that IL-10 (20 ng/ml) inhibited the expression of both MMPs significantly compared with enzyme levels induced after 48 h of infection with T. cruzi. To evaluate whether the inhibition of mRNA expression exerted by IL-10 correlated with the activity of these enzymes, supernatants of cultured cardiomyocytes treated or not with IL-10 and infected for 72 h were tested by zymography. IL-10 significantly inhibited the gelatinolytic activity of proenzymes MMP-9 and MMP-2 induced by infection with T. cruzi in cardiomyocytes (Figure 5B). This evidence concerns the gene MMP9 and infection.