Trimetazidine suppresses oxidative stress, inhibits MMP-2 and MMP-9 expression, and prevents cardiac rupture in mice with myocardial infarction.

BACKGROUND/AIMS: Cardiac rupture (CR) is a catastrophic complication of acute myocardial infarction (MI). At present, there are no effective pharmacological strategies for preventing post-MI rupture. Here we investigated the effect of trimetazidine (TMZ) on post-MI CR. METHODS: MI models were induced by left coronary artery ligation in male C57BL/6 mice. Animals allocated to the rupture incidence were closely monitored for 7 days; autopsy was performed once animals were found dead to determine the reason of death. Heart function was detected by echocardiography. Oxidative stress markers and matrix metalloproteinases (MMPs) were analyzed by Western Blotting. RESULTS: TMZ markedly reduced the post-MI CR incidence of mice. We found that the expression of metalloproteinase (MMP) -2 and MMP-9 in the TMZ-treated group was significantly lower than the saline-treated group. Further, TMZ markedly attenuated MI-induced oxidative stress. To investigate the mechanism of the effect of TMZ on CR, we pretreated H9c2 cells with H2 O2 and found that TMZ treatment markedly decreased H2 O2 -induced MMP-2 and MMP-9 expression. TMZ prevents CR through inhibition of oxidative stress, which is attributable to the down-regulation of MMP-2, MMP-9 expression. CONCLUSIONS: Our findings indicate that TMZ suppresses oxidative stress, inhibits MMP-2 and MMP-9 expression, and prevents CR in mice with MI.

Splenic Ly6Chi monocytes contribute to adverse late post-ischemic left ventricular remodeling in heme oxygenase-1 deficient mice.

Heme oxygenase-1 (Hmox1) is a stress-inducible protein crucial in heme catabolism. The end products of its enzymatic activity possess anti-oxidative, anti-apoptotic and anti-inflammatory properties. Cardioprotective effects of Hmox1 were demonstrated in experimental models of myocardial infarction (MI). Nevertheless, its importance in timely resolution of post-ischemic inflammation remains incompletely understood. The aim of this study was to determine the role of Hmox1 in the monocyte/macrophage-mediated cardiac remodeling in a mouse model of MI. Hmox1 knockout (Hmox1-/-) and wild-type (WT, Hmox1+/+) mice were subjected to a permanent ligation of the left anterior descending coronary artery. Significantly lower incidence of left ventricle (LV) free wall rupture was noted between 3rd and 5th day after MI in Hmox1-/- mice resulting in their better overall survival. Then, starting from 7th until 21st day post-MI a more potent deterioration of LV function was observed in Hmox1-/- than in the surviving Hmox1+/+ mice. This was accompanied by higher numbers of Ly6Chi monocytes in peripheral blood, as well as higher expression of monocyte chemoattractant protein-1 and adhesion molecules in the hearts of MI-operated Hmox1-/- mice. Consequently, a greater post-MI monocyte-derived myocardial macrophage infiltration was noted in Hmox1-deficient individuals. Splenectomy decreased the numbers of circulating inflammatory Ly6Chi monocytes in blood, reduced the numbers of proinflammatory cardiac macrophages and significantly improved the post-MI LV function in Hmox1-/- mice. In conclusion, Hmox1 deficiency has divergent consequences in MI. On the one hand, it improves early post-MI survival by decreasing the occurrence of cardiac rupture. Afterwards, however, the hearts of Hmox1-deficient mice undergo adverse late LV remodeling due to overactive and prolonged post-ischemic inflammatory response. We identified spleen as an important source of these cardiovascular complications in Hmox1-/- mice.

The implications of serum enzymes and coagulation activities in postinfarction myocardial rupture.

OBJECTIVE: Associations between cardiovascular diseases and serum enzymes or coagulation activities have been sufficiently documented in patients with myocardial infarction. However, the alterations of these biomarkers in patients with postinfarction myocardial rupture have rarely been reported. The aim of this study is to present the profiles of the markers in patients with postinfarction myocardial rupture. METHODS: From 2004 to 2008, 19 consecutive patients were referred to this hospital for surgical repair of postinfarction myocardial rupture. Eight (42.1%) patients had free wall rupture, 5 (26.3%) had papillary muscle rupture, 5 (26.3%) had ventricular septal rupture, and 1 (5.3%) had double structure (ventricular septum + free wall) rupture. Thirteen patients survived the operation, and 6 died. Laboratory findings including serum enzymes and coagulation activities were collected and analyzed. RESULTS: The coagulation markers and serum enzymes except for fibrinogen increased significantly after the development of myocardial rupture. Statistical differences in D-dimer, partial thromboplastin time, peak lactate dehydrogenase, peak creatine kinase and creatine kinase fraction MB were found between non-survivors and survivors. Troponin I values were elevated significantly during the early days after the onset or surgical repair of myocardial rupture. Multivariant regression analysis did not show any significant relationship between creatine phosphokinase fraction MB (Y) and D-dimer (X1) or fibrinogen (X2). CONCLUSION: Myocardial rupture leads to extremely high serum enzyme and coagulation activities except for fibrinogen after the onset. The evaluation of these biomarkers may help in making diagnostic and treatment decisions and in judging the clinical prognosis of such patients.

The implications of serum enzymes and coagulation activities in postinfarction myocardial / As implicações de enzimas séricas e atividades de coagulação em ruptura cardíaca pós-infarto do miocárdio

OBJECTIVE: Associations between cardiovascular diseases and serum enzymes or coagulation activities have been sufficiently documented in patients with myocardial infarction. However, the alterations of these biomarkers in patients with postinfarction myocardial rupture have rarely been reported. The aim of this study is to present the profiles of the markers in patients with postinfarction myocardial rupture. METHODS: From 2004 to 2008, 19 consecutive patients were referred to this hospital for surgical repair of postinfarction myocardial rupture. Eight (42.1%) patients had free wall rupture, 5 (26.3%) had papillary muscle rupture, 5 (26.3%) had ventricular septal rupture, and 1 (5.3%) had double structure (ventricular septum + free wall) rupture. Thirteen patients survived the operation, and 6 died. Laboratory findings including serum enzymes and coagulation activities were collected and analyzed. RESULTS: The coagulation markers and serum enzymes except for fibrinogen increased significantly after the development of myocardial rupture. Statistical differences in D-dimer, partial thromboplastin time, peak lactate dehydrogenase, peak creatine kinase and creatine kinase fraction MB were found between non-survivors and survivors. Troponin I values were elevated significantly during the early days after the onset or surgical repair of myocardial rupture. Multivariant regression analysis did not show any significant relationship between creatine phosphokinase fraction MB (Y) and D-dimer (X1) or fibrinogen (X2). CONCLUSION: Myocardial rupture leads to extremely high serum enzyme and coagulation activities except for fibrinogen after the onset. The evaluation of these biomarkers may help in making diagnostic and treatment decisions and in judging the clinical prognosis of such patients.

OBJETIVO: As associações entre doenças cardiovasculares e enzimas sorológicas ou atividades de coagulação foram amplamente documentadas em pacientes com infarto do miocárdio. No entanto, as alterações destes biomarcadores em pacientes com ruptura cardíaca após infarto do miocárdio foram raramente relatadas. O objetivo deste estudo é apresentar o perfil dos biomarcadores em pacientes com ruptura cardíaca após infarto do miocárdio. MÉTODOS: De 2004 a 2008, 19 pacientes consecutivos foram referidos a este hospital para correção cirúrgica de ruptura cardíaca após infarto do miocárdio. Oito (42,1%) pacientes tiveram ruptura livre de parede, cinco (26,3%) ruptura de músculo papilar, cinco (26,3%) ruptura do septo interventricular e um (5,3%) ruptura dupla de estruturas, envolvendo tanto septo ventricular como parede livre. Treze pacientes sobreviveram à operação e seis faleceram. Amostras sanguíneas foram coletadas e analisadas para mensuração de enzimas sorológicas e atividade de coagulação. RESULTADOS: Os marcadores de coagulação e enzimas com exceção de fibrinogênio aumentaram significativamente depois do desenvolvimento da ruptura do miocárdio. Diferenças estatísticas foram achadas entre não-sobreviventes e sobreviventes em relação a concentração de dímeros-D, tempo de trombina, pico de lactato desidrogenase, creatinoquinase máximo e fração MB da creatinoquinase. Os valores de troponina I foram elevados significativamente durante os primeiros dias depois do infarto ou do reparo cirúrgico da ruptura do miocárdio. A análise de regressão multivariada não mostrou qualquer relação significativa entre fração MB da creatinoquinase e dímeros-D nem fibrinogênio. CONCLUSÕES: A ruptura do miocárdio induz importante elevação de marcadores enzimáticos e de atividade de coagulação, exceto fibrinogênio. As diferenças nestes biomarcadores entre não-sobreviventes e sobreviventes podem ser de grande ajuda no diagnóstico e nas decisões de tratamento, assim como na avaliação do prognóstico clínico de tais pacientes.

Critical role for white blood cell NAD(P)H oxidase-mediated plasminogen activator inhibitor-1 oxidation and ventricular rupture following acute myocardial infarction.

Plasminogen activator inhibitor-1 (PAI-1) is an oxidant-sensitive protease inhibitor that is inactivated by oxidation and has a critical role in ventricular remodeling post myocardial infarction (MI). PAI-1 knockout (KO) mice die within 7days of myocardial infarction post MI due to increased plasmin activity leading to ventricular rupture. The goal of this study was to assess the relevant pathways of leukocyte-derived oxidants post MI that alter PAI-1 activity. Transplantation of wild-type (WT) bone marrow into PAI-1 null mice prolonged survival after MI (WT marrow: 41.66% vs. PAI-1 KO marrow: 0% in PAI-1 KO mice at day 7 (p<0.02). To determine relevant enzyme systems, we transplanted marrow from mice with specific deletions relevant to leukocyte-derived oxidants (NAD(P)H oxidase, iNOS, myeloperoxidase (MPO)) to determine which deletion controls PAI-1 oxidative inactivation and prolongs survival. MI was induced by ligation of the left anterior descending artery (LAD) and the incidence of cardiac rupture was monitored. PAI-1 KO transplanted with MPO KO, or iNOS KO bone marrow died within 9 days after MI. PAI-1 KO mice transplanted with p47(phox) KO marrow exhibited prolonged survival 21 days after MI (30% survival, p<0.03, n=10) compared to WT marrow (8.3%, n=12). Three days after MI, PAI-1 KO mice transplanted with p47(phox) KO marrow had increased PAI-1 activity and decreased nitration of PAI-1 in myocardial tissue compared to PAI-1 KO mice transplanted with WT marrow. These data suggest that modulating O(2)(•-) generation by NAD(P)H oxidase appears to be a therapeutically relevant target for increasing myocardial PAI-1 levels after MI, whereas downstream enzymes like MPO and iNOS may not be.

Increased matrix metalloproteinase-8 and -9 activity in patients with infarct rupture after myocardial infarction.

BACKGROUND: Infarct rupture is a usually fatal complication of myocardial infarction (MI), for which no molecular mechanism has been described in humans. Experimental evidence in mouse models suggests that the degradation of the extracellular matrix by matrix metalloproteinases (MMPs) plays an important role in infarct rupture. The present study was designed to study the role of MMP-2, MMP-8, and MMP-9 in human infarct rupture. METHODS: Heart samples were obtained from patients who died from infarct rupture and control MI patients. The MMP activity was determined by zymography and quantitative immunocapture activity assay. TIMP-1 levels were measured and immunohistochemistry for MMP-2 and MMP-9 was performed. RESULTS: The amounts of both total and active MMP-8 and MMP-9 were significantly higher in ruptured infarct tissue than in control MI tissue, but no differences in MMP-2 activity were observed. Furthermore, the number of inflammatory cells was significantly higher in the ruptured infarcts than in control infarcts. CONCLUSIONS: These data suggest that increased MMP-8 and MMP-9 activity in the infarct area, caused by a more prominent infiltration of inflammatory cells, contribute to infarct rupture in humans.

Matrix metalloproteinases as valid clinical targets.

The matrix metalloproteinase family of enzymes has been a pharmaceutical target for over 20 years. In that time, many drugs have been developed but none have successfully passed clinical trials. A significant problem has been development of dose-limiting side-effects that were revealed during long-term clinical trials in diseases such as arthritis and various cancers. There are, however, other clinical settings where evidence for MMP function contributing to the pathophysiology of disease is strong. A number of these settings will be discussed here together with evidence from animal models that MMP inhibition is a valid strategy to be considered. A major advantage with many of these settings is that drug exposure may not have to be long-term and/or systemic thus reducing the possibility that side-effects will stymie MMPI-based therapy.

Temporal changes in matrix metalloproteinase expression and inflammatory response associated with cardiac rupture after myocardial infarction in mice.

We previously found that male mice with myocardial infarction (MI) had a high rate of cardiac rupture, which generally occurred at 3 to 5 days after MI. Since matrix metalloproteinases (MMPs) play an important role in infarct healing, tissue repair and extracellular matrix (ECM) remodeling post-MI, we studied the temporal relationship of MMP expression and inflammatory response to cardiac rupture after acute MI. Male C57BL/6J mice were subjected to MI (induced by ligating the left anterior descending coronary artery) and killed 1, 2, 4, 7 or 14 days after MI. MMP-2 and MMP-9 activity in the heart were measured by zymography. Collagen content was measured by hydroxyproline assay. We found that after MI, MMP-9 activity increased as early as 1 day and reached a maximum by 2-4 days, associated with a similar increase in neutrophil and macrophage infiltration in the infarct area. MMP-2 started to increase rapidly within 4 days, reaching a maximum by 7 days and remaining high even at 14 days. Intense macrophage infiltration appeared by 4 days after MI and then gradually decreased within 7 to 14 days. Collagen content was unchanged until 4 days after MI, at which point it increased and remained high thereafter. Our data suggest that in mice, overexpression of MMP-2 and MMP-9 (possibly expressed mainly by neutrophils and macrophages) may lead to excessive ECM degradation in the early phase of MI, impairing infarct healing and aggravating early remodeling which in turn causes cardiac rupture.