The role of matrix metalloproteinases induced angiogenesis during transition from compensatory cardiac hypertrophy to cardiac failure : therapeutic effects of hydrogen sulfide.

Background: Although matrix metalloproteinase (MMPs) and tissue inhibitor of metalloproteinase (TIMPs) play a vital role in tumor angiogenesis and TIMP-3 causes apoptosis, their role in cardiac angiogenesis is unknown. Interestingly, a disruption of coordinated cardiac hypertrophy and angiogenesis contributes to the transition to heart failure, however, the proteolytic and anti-angiogenic mechanisms of transition from compensatory hypertrophy to decompensatory heart failure are unclear. Previous studies have shown the cardio protective role of hydrogen sulfide (H2S) in myocardial ischemia, infarction and heart failure, but its role during transition from compensatory cardiac hypertrophy to heart failure is yet to be unveiled. We hypothesize that in pathological pressure overload of the heart, cardiac matrix remodeling is induced by an increase in angiogenic growth factors during the compensatory hypertrophy phase and an increase in antiangiogenic factors during the decompensatory heart failure phase. H2S mitigates the transition from compensatory hypertrophy to decompensatory heart failure by increasing angiogenesis and decreasing fibrosis. Methods: In the first set of experiments, we have created ascending aortic banding (AB) in the mice to mimic pressure overload on the heart and studied the ventricular remodeling events associated with chronic pressure overload. Male wild type mice were used and all animal procedures were performed in accordance with National Institute of Health guidelines for animal research and were reviewed and approved by the Institute Animal Care and use Committee of University of Louisville. Sham animals underwent similar procedures except for aortic banding. Animals were studied at 3 weeks (compensatory phase) and 8 weeks period (decompensatory phase) and compared with sham groups. In the second set of experiment, similar protocol was followed, and animals were treated with hydrogen sulfide (H2S) for 6 weeks by giving sodium hydrosulfide (NaHS) in drinking water and compared with untreated groups. Molecular and functional data were assessed by echocardiography, pressure-volume (P-V) study, immunohistochemistry, histology, western blot, and x-ray angiography. Results: We found that in the first set of experiments, expression of MMP-2 increased along with angiogenic growth factor, vascular endothelial growth factor (VEGF) during compensatory phase (AB 3 weeks group). Expression of MMP-9, TIMP-3 and anti-angiogenic factors, angiostatin, and endostatin increased during decompensatory phase (AB 8 weeks group). There was increased deposition of fibrosis during the decompensatory phase. Sy treating with H2S, we noticed that there was increased expression of VEGF and MMP-2 in AS 8 weeks group than in untreated AS 8 weeks group. Interestingly, the expression of MMP-9, TIMP-3 and anti-angiogenic factors angiostatin and endostatin decreased in H2S treated AS 8 weeks group than in the untreated group. There was significant reduction of fibrosis in treated AS 8 weeks group. Left ventricular function also improved in H2S treated AS 8 weeks group. Conclusion: we conclude that under chronic pressure overload, expression of MMP-2 is induced which in turn increases the release of angiogenic growth factors in compensatory cardiac hypertrophy. The expression of MMP-9 and TIMP-3 is also increased leading to a release of anti-angiogenic factors in decompensatory heart failure. Hydrogen sulfide mitigates this transition to decompensatory heart failure not only by inducing MMP-2NEGF but also inhibiting MMP-9/TIMP-3 and anti-angiogenic factors

Mitochondrial division/mitophagy inhibitor (Mdivi) Ameliorates Pressure Overload Induced Heart Failure

Background: We have previously reported the role of anti-angiogenic factors in inducing the transition from compensatory cardiac hypertrophy to heart failure and the significance of MMP-9 and TIMP-3 in promoting this process during pressure overload hemodynamic stress. Several studies reported the evidence of cardiac autophagy, involving removal of cellular organelles like mitochondria (mitophagy), peroxisomes etc., in the pathogenesis of heart failure. However, little is known regarding the therapeutic role of mitochondrial division inhibitor (Mdivi) in the pressure overload induced heart failure. We hypothesize that treatment with mitochondrial division inhibitor (Mdivi) inhibits abnormal mitophagy in a pressure overload heart and thus ameliorates heart failure condition. Materials and Methods: To verify this, ascending aortic banding was done in wild type mice to create pressure overload induced heart failure and then treated with Mdivi and compared with vehicle treated controls. Results: Expression of MMP-2, vascular endothelial growth factor, CD31, was increased, while expression of anti angiogenic factors like endostatin and angiostatin along with MMP-9, TIMP-3 was reduced in Mdivi treated AB 8 weeks mice compared to vehicle treated controls. Expression of mitophagy markers like LC3 and p62 was decreased in Mdivi treated mice compared to controls. Cardiac functional status assessed by echocardiography showed improvement and there is also a decrease in the deposition of fibrosis in Mdivi treated mice compared to controls

The pharmacological regulation of cellular mitophagy

Small molecules are pharmacological tools of considerable value for dissecting complex biological processes and identifying potential therapeutic interventions. Recently, the cellular quality-control process of mitophagy has attracted considerable research interest; however, the limited availability of suitable chemical probes has restricted our understanding of the molecular mechanisms involved. Current approaches to initiate mitophagy include acute dissipation of the mitochondrial membrane potential (ΔΨm) by mitochondrial uncouplers (for example, FCCP/CCCP) and the use of antimycin A and oligomycin to impair respiration. Both approaches impair mitochondrial homeostasis and therefore limit the scope for dissection of subtle, bioenergy-related regulatory phenomena. Recently, novel mitophagy activators acting independently of the respiration collapse have been reported, offering new opportunities to understand the process and potential for therapeutic exploitation. We have summarized the current status of mitophagy modulators and analyzed the available chemical tools, commenting on their advantages, limitations and current applications

Attenuation of doxorubicin-induced cardiotoxicity by mdivi-1: a mitochondrial division/mitophagy inhibitor

Doxorubicin is one of the most effective anti-cancer agents. However, its use is associated with adverse cardiac effects, including cardiomyopathy and progressive heart failure. Given the multiple beneficial effects of the mitochondrial division inhibitor (mdivi-1) in a variety of pathological conditions including heart failure and ischaemia and reperfusion injury, we investigated the effects of mdivi-1 on doxorubicin-induced cardiac dysfunction in naïve and stressed conditions using Langendorff perfused heart models and a model of oxidative stress was used to assess the effects of drug treatments on the mitochondrial depolarisation and hypercontracture of cardiac myocytes. Western blot analysis was used to measure the levels of p-Akt and p-Erk 1/2 and flow cytometry analysis was used to measure the levels p-Drp1 and p-p53 upon drug treatment. The HL60 leukaemia cell line was used to evaluate the effects of pharmacological inhibition of mitochondrial division on the cytotoxicity of doxorubicin in a cancer cell line. Doxorubicin caused a significant impairment of cardiac function and increased the infarct size to risk ratio in both naïve conditions and during ischaemia/reperfusion injury. Interestingly, co-treatment of doxorubicin with mdivi-1 attenuated these detrimental effects of doxorubicin. Doxorubicin also caused a reduction in the time taken to depolarisation and hypercontracture of cardiac myocytes, which were reversed with mdivi-1. Finally, doxorubicin caused a significant elevation in the levels of signalling proteins p-Akt, p-Erk 1/2, p-Drp1 and p-p53. Co-incubation of mdivi-1 with doxorubicin did not reduce the cytotoxicity of doxorubicin against HL-60 cells. These data suggest that the inhibition of mitochondrial fission protects the heart against doxorubicin-induced cardiac injury and identify mitochondrial fission as a new therapeutic target in ameliorating doxorubicin-induced cardiotoxicity without affecting its anti-cancer properties

Increased Circulating Tissue Inhibitor of Metalloproteinase-2 Is Associated With Resistant Hypertension

Resistant hypertension (RH) is associated with organ damage and cardiovascular risk. Evidence suggests the involvement of matrix metalloproteinase 2 (MMP‐2) and tissue inhibitor of metalloproteinase 2 (TIMP‐2) in hypertension and in cardiovascular remodeling. The aim of this study was to assess the levels of MMP‐2 and TIMP‐2 in RH and its relation with organ damage, including arterial stiffness and cardiac hypertrophy. MMP‐2 and TIMP‐2 levels were compared among 19 patients with normotension (NT), 116 with nonresistant hypertension (HTN) and 116 patients with resistant HTN (RH). MMP‐2 levels showed no differences among NT, HTN, and RH groups, while TIMP‐2 levels were higher in RH compared with HTN and NT groups (90.0 [76.1–107.3] vs 70.1 [57.7–88.3] vs 54.7 [40.9–58.1] ng/mL, P<.01), respectively. MMP‐2/TIMP‐2 ratio was reduced in the RH group compared with the HTN and NT groups (2.7 [1.9–3.4] vs 3.3 [2.6–4.2] vs 4.9 [4.5–5.3], P<.01), respectively. No associations were found between MMP‐2 levels, TIMP‐2, and MMP‐2/TIMP‐2 ratio with cardiac hypertrophy and arterial stiffness in the RH and HTN groups. Finally, in a regression analysis, reduced MMP‐2/TIMP‐2 ratio and increased TIMP‐2 levels were independently associated with RH. The present findings provide evidence that TIMP‐2 is associated with RH and might be a possible biomarker for screening RH patients

Cardiac matrix: A clue for future therapy

AbstractCardiac muscle is unique because it contracts ceaselessly throughout the life and is highly resistant to fatigue. The marvelous nature of the cardiac muscle is attributed to its matrix that maintains structural and functional integrity and provides ambient micro-environment required for mechanical, cellular and molecular activities in the heart. Cardiac matrix dictates the endothelium myocyte (EM) coupling and contractility of cardiomyocytes. The matrix metalloproteinases (MMPs) and their tissue inhibitor of metalloproteinases (TIMPs) regulate matrix degradation that determines cardiac fibrosis and myocardial performance. We have shown that MMP-9 regulates differential expression of micro RNAs (miRNAs), calcium cycling and contractility of cardiomyocytes. The differential expression of miRNAs is associated with angiogenesis, hypertrophy and fibrosis in the heart. MMP-9, which is involved in the degradation of cardiac matrix and induction of fibrosis, is also implicated in inhibition of survival and differentiation of cardiac stem cells (CSC). Cardiac matrix is distinct because it renders mechanical properties and provides a framework essential for differentiation of cardiac progenitor cells (CPC) into specific lineage. Cardiac matrix regulates myocyte contractility by EM coupling and calcium transients and also directs miRNAs required for precise regulation of continuous and synchronized beating of cardiomyocytes that is indispensible for survival. Alteration in the matrix homeostasis due to induction of MMPs, altered expression of specific miRNAs or impaired signaling for contractility of cardiomyocytes leads to catastrophic effects. This review describes the mechanisms by which cardiac matrix regulates myocardial performance and suggests future directions for the development of treatment strategies in cardiovascular diseases