Reduction of myocardial infarct size by doxycycline: A role for plasmin inhibition

Abstract

Myocardial ischemia-reperfusion (I/R) is associated with the activation of matrix metalloproteinases (MMPs) and serine proteases. We hypothesized that activation of MMPs and the serine protease plasmin contribute to early cardiac myocyte death following I/R and that broad-spectrum protease inhibition with doxycycline (DOX) preserves myocyte viability. Rats treated daily with or without DOX beginning 48 h prior to experimentation were subjected to 30 min of coronary occlusion and 2 days of reperfusion. DOX pre-treatment reduced infarct size by 37%. DOX attenuated increases in MMP-9 and plasmin levels as determined by gelatin zymography and immunoblot, respectively. Neutrophil extravasation was unaltered by DOX as assessed by myeloperoxidase (MPO) activity. To examine the contribution of MMP-9 and plasmin to myocyte injury, cultures of neonatal rat ventricular myocytes (NRVMs) were treated for 48 h with 83 kDa MMP-9 or plasminogen in the presence or absence of DOX. MMP-9 treatment did not affect myocyte viability. Plasminogen treatment led to increased plasmin activity, resulting in loss of beta1-integrin, NRVM detachment and apoptosis. DOX co-treatment inhibited plasmin activity and preserved NRVM attachment, whereas co-treatment with the broad-spectrum MMP inhibitor GM6001 had no effect. These results indicate that plasmin causes disruption of myocyte attachment and viability independently of MMP activation in vitro and that inhibition of plasmin by DOX may reduce I/R-induced myocyte death in vivo through the inhibition of plasmin.

Serum Proteomic Signature of Human Chagasic Patients for the Identification of Novel Potential Protein Biomarkers of Disease

“…A deficiency of, as well as up-regulation of, PLG and F2 beyond physiological levels can lead to multiple pathological outcomes, including thrombosis caused by partial or inadequate degradation of blood clots, defective wound healing, and excessive bleeding (55)(56)(57). Plasmin is postulated to influence the progression of cardiovascular diseases through activation of collagenases and matrix metalloproteinases and resultant degradation of matrix proteins (58) and has also been implicated in metabolic syndrome (59). PLG, F2, and their receptors are also closely linked to regulation of cardiovascular inflammatory responses and have been suggested by others to influence cell migration through regulation of growth factor and chemokine pathways and acute phase response signaling through activation of C3 component of complement system (60).…”

Doxycycline Attenuates Isoproterenol- and Transverse Aortic Banding-Induced Cardiac Hypertrophy in Mice

“…MMPs are known to contribute to the development of various heart defects, including CH and myocardial infarction, and DOX, an FDA-approved drug with a known absorption/ toxicity profile, has been shown to inhibit MMPs (Golub et al, 1998;Grenier et al, 2002;Griffin et al, 2005). This prompted us to test the drug in two different mouse models of CH.…”

“…In addition to several other candidates, doxycycline (DOX) was predicted as a potential therapy for pathological CH. The software identified DOX as a potential therapeutic partly because it was previously shown to generally inhibit MMPs (Griffin et al, 2005), which suggested to us that it might reduce a hypertrophic phenotype. DOX is a very well tolerated antibiotic and is also FDA approved, making it a particularly attractive candidate for CH therapy.…”

“…DOX is a very well tolerated antibiotic and is also FDA approved, making it a particularly attractive candidate for CH therapy. Furthermore, DOX has been shown in ischemic-reperfusion studies to exert a protective effect when administered before the induction of myocardial infarction (Villarreal et al, 2003;Griffin et al, 2005). To evaluate the efficacy of DOX, mice were treated with the drug after induction of CH with the ␤-adrenergic agonist, isoproterenol (ISO), or TAB.…”

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

“…In the rat model of MI, a robust and early increase in myocardial levels for the gelatinases MMP-2 and MMP-9 have been reported (138,334,425,442). Using an MMP-2/-9 specific fluorogenic substrate, Villarreal et al (469) demonstrated significant myocardial proteolytic activity as early as 2 h following coronary ligation (469).…”