Abstract
BackgroundLittle is known about the involvement of matrix metalloproteinases (MMPs) in cardiac vascular remodelling induced by exercise. Our aim was to evaluate and localize MMP-2 and MMP-9’s activities in relation to capillary proliferation in mouse hearts trained for 15, 30 and 45 days.MethodsSixty-three mice were randomly assigned to 7 groups: four control sedentary groups (C0, C15, C30 and C45) and three groups trained by an endurance protocol (T15, T30 and T45). MMP-2 and MMP-9 were examined with zymography and immunostaining analyses. Capillary proliferation was evaluated counting the number of CD31-positive cells.ResultsDifferent activity patterns of the latent form of both MMPs were found. Pro-MMP-9 increased after 15 days of training; whereas pro-MMP-2 gradually decreased after 30 and 45 days of training below the control groups. The latter was inversely correlated with capillary growth. MMP-9 was mainly localized in myocardiocytes and less evident in capillaries. Conversely, MMP-2 was more intense in capillary endothelial cells and slightly in myocardiocytes.ConclusionsA different spatiotemporal modulation of pro-MMP-2 and pro-MMP-9 activities has been detected in the myocardium during angiogenesis related to the aerobic training. These results can be useful to draw up training protocols for improving the performance of healthy and diseased human hearts.
Highlights
Little is known about the involvement of matrix metalloproteinases (MMPs) in cardiac vascular remodelling induced by exercise
Comparing the gelatinolytic activity of pro-MMP-2 and pro-MMP-9, we observed that proMMP-2 levels were higher than pro-MMP-9 either in sedentary and trained mouse hearts (Figure 3B)
This study has demonstrated that the activity of proMMP-2 and pro-MMP-9 is differently modulated during cardiac angiogenesis induced by aerobic training
Summary
Little is known about the involvement of matrix metalloproteinases (MMPs) in cardiac vascular remodelling induced by exercise. MMPs are zinc-dependent endoproteinases able to degrade various extracellular matrix (ECM) components and are synthesized as latent pro-enzymes activated via cleavage of the regulatory peptide sequence by serine proteases, such as plasmin, and other MMPs [6]. They can contribute to the angiogenic process in different ways including endothelial cell migration through surrounding tissues by disrupting ECM barriers [12]; the release of sequestered angiogenic factors, such as fibroblast growth factors-2 (FGF-2) or vascular endothelial growth factor (VEGF); the inhibition of angiogenesis by generating anti-angiogenic fragments from ECM molecules, such as endostatin and tumstatin [13]
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