Expression of the tissue inhibitor of metalloproteinase-3 by transplanted VSMCs modifies heart structure and function after myocardial infarction

The TIMP protein family: diverse roles in pathophysiology

The tissue inhibitors of matrix metalloproteinases (TIMPs) are a family of four matrisome proteins classically defined by their roles as the primary endogenous inhibitors of metalloproteinases (MPs). Their functions however are not limited to MP inhibition, with each family member harboring numerous MP-independent biological functions that play key roles in processes such as inflammation and apoptosis. Because of these multifaceted functions, TIMPs have been cited in diverse pathophysiological contexts. Herein, we provide a comprehensive overview of the MP-dependent and -independent roles of TIMPs across a range of pathological conditions. The potential therapeutic and biomarker applications of TIMPs in these disease contexts are also considered, highlighting the biomedical promise of this complex and often misunderstood protein family.

Naoxintong capsule limits myocardial infarct expansion by inhibiting platelet activation through the ERK5 pathway

BACKGROUND

In the clinic, Naoxintong capsule (NXT) has been applied in two level prevention of ischemic disease. However, its mechanism of action requires further study.

PURPOSE

This study investigated whether NXT could affect platelet function and activation under ischemic pathological conditions.

MATERIALS AND METHODS

Wistar rats were divided into six groups, sham, saline, NXT (250, 500, 1000 mg/kg), and aspirin group (10 mg/kg). For the pre-treatment assays, MI model was established after pre-administration of saline, NXT-L, NXT-M, NXT-H, and aspirin respectively for 14 days, and after surgery, there were no continuous treatments. For the post-treatment assay, rats were orally administered for 3 days after MI. FeCl3-induced thrombosis model was applied to determine the thrombus wet weight. Bleeding time was used to assess the ability of the platelets to develop a hemostatic plug.

RESULTS

NXT decreased infarct size, decreased LDH, CK, and CK-MB values, and improved cardiac function. NXT inhibited platelets activation through reducing CD62P-positive platelets and inhibited infarct expansion by decreasing the number of CD45-positive cells and the amount of MMP9 secreted into the heart tissue. Mechanistically, NXT inhibited platelets activation through decreasing ROS levels, decreasing ERK5 phosphorylation, and increasing RAC1 phosphorylation in MI rats. Pre-treatment with NXT decreased thrombus formation and had normal bleeding times.

CONCLUSION

NXT showed obviously preventive effects, which was associated with negative control of platelet activation. The above results provide a basis for clinically expanding application of NXT.

Biology of Tissue Inhibitor of Metalloproteinase 3 (TIMP3), and Its Therapeutic Implications in Cardiovascular Pathology

Tissue inhibitor of metalloproteinase 3 (TIMP3) is unique among the four TIMPs due to its extracellular matrix (ECM)-binding property and broad range of inhibitory substrates that includes matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs), and ADAM with thrombospondin motifs (ADAMTSs). In addition to its metalloproteinase-inhibitory function, TIMP3 can interact with proteins in the extracellular space resulting in its multifarious functions. TIMP3 mRNA has a long 3' untranslated region (UTR) which is a target for numerous microRNAs. TIMP3 levels are reduced in various cardiovascular diseases, and studies have shown that TIMP3 replenishment ameliorates the disease, suggesting a therapeutic potential for TIMP3 in cardiovascular diseases. While significant efforts have been made in identifying the effector targets of TIMP3, the regulatory mechanism for the expression of this multi-functional TIMP has been less explored. Here, we provide an overview of TIMP3 gene structure, transcriptional and post-transcriptional regulators (transcription factors and microRNAs), protein structure and partners, its role in cardiovascular pathology and its application as therapy, while also drawing reference from TIMP3 function in other diseases.

Real-Ambient Particulate Matter Exposure-Induced Cardiotoxicity in C57/B6 Mice

It is generally accepted that exposure to particulate matter (PM) increases the risk of cardiovascular-related morbidity and mortality, though the exact mechanism behind this has yet to be elucidated. Oxidative stress plays a potentially important role in the mechanism of toxicity, with Nrf2 serving as a major antioxidant gene. In the current study, a Nrf2 knockout mouse model was used in combination with an individual ventilated cage (IVC)-based real-ambient PM exposure system to assess the potential cardiotoxicity induced by real-ambient PM exposure and the potential role of Nrf2 and related signaling in this endpoint. After 6- or 11-weeks exposure to PM, ICP-mass spectrometry was used to assess the metal depositions in the heart tissue following PM exposure. Functional and morphological changes in the hearts were investigated with echocardiography and histopathology, and oxidative stress levels were assessed with a serum malondialdehyde content assay. In the further mechanistic study, an RNA-seq technique was utilized to assess the gene transcription status in the hearts of C57/B6 mice exposed to PM with or without Nrf2 knockout. The expression levels of genes of interest were then further investigated with quantitative real-time PCR and western blotting. The results indicated that PM exposure resulted in significant elevation of sodium, potassium, selenium, and ferrum levels in mouse heart tissue. Meanwhile, significantly altered heart function and morphology were observed. Interestingly, Nrf2 knockout led to abolishment of PM-induced effects in several functional parameters but not the morphological changes. Meanwhile, elevated malondialdehyde content was observed in Nrf2 knockout animals. RNA-seq results revealed thousands of genes altered by PM exposure and/or Nrf2 knockout, and this affected several pathways, such as MAPK, phagosome, calcium signaling, and JAK-STAT. In subsequent molecular studies, enhanced nuclear translocation of Nrf2 was also observed following PM exposure, while the MAPK signaling pathway along with related JAK-STAT and TGF-β1 pathway genes, such as p38MAPK, AKT, TAK1, JAK1, STAT3, GRB2, TGFb1, and SMAD2, were confirmed to be affected by PM exposure and/or Nrf2 knockout. The data suggested that PM may induce cardiotoxicity in C57/B6 mice in which Nrf2 plays both protective and detrimental roles involving cardiac-related pathways, such as MAPK, JAK-STAT, and TGF-β1.

Adenovirus-mediated overexpression of sST2 attenuates cardiac injury in the rat with severe acute pancreatitis

AIMS

Severe acute pancreatitis (SAP) is a serious disease associated with systematic inflammation and multiple organs dysfunction. Soluble ST2 (sST2), a member of the Toll interleukin (IL)-1 receptor (TIR) superfamily, has been demonstrated to exert immune-regulatory and anti-inflammatory properties in several inflammation-related diseases. In this study, we investigated whether transfer of sST2 gene by adenovirus vector could attenuate sodium taurocholate-induced SAP and associated cardiac injury.

MAIN METHODS

A rat model of SAP was induced by retrograde injection of 5% sodium taurocholate (1 ml/kg) into the biliopancreatic duct. Rats in the treatment groups were intravenously injected with adenovirus expressing sST2 (Ad-sST2, 1 × 10⁹ particles/rat) or green fluorescent protein (Ad-GFP) via the tail vein 48 h before SAP induction. Histological changes in the pancreatic and heart tissues, and parameters for evaluating SAP and associated cardiac injury were determined at 24 h after SAP.

KEY FINDINGS

Sodium taurocholate induced obvious pathological changes in pancreas and elevated serum levels of amylase and lipase. Furthermore, SAP animals exhibited significant cardiac impairment, evidenced by decreased cardiac function, increased myocardial apoptosis and cardiac-related enzymes including creatine kinase isoenzyme, lactate dehydrogenase, and Troponin T. Administration of Ad-sST2 markedly improved the structure of pancreas and heart tissues, and reversed the alterations in serum amylase, lipase and cardiac-related enzymes. In addition, Ad-sST2 treatment downregulated pro-inflammatory cytokines production, demonstrating the anti-inflammatory property of sST2.

SIGNIFICANCE

Our results suggest that administration of Ad-sST2 significantly attenuated the severity of SAP and associated cardiac damage, and the cardioprotective effect is associated with its anti-inflammatory action.

Danshen injection prevents heart failure by attenuating post-infarct remodeling

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen Injection (DSI) is a traditional Chinese medicine extracted from Danshen, prepared from the dried root and rhizome of Salvia miltiorrhiza Bunge. Danshen is an ancient antipyretic traditional Chinese medicine which is mostly used to improve blood circulation and dispel blood stasis. Danshen decoction or liquor-fried Danshen (with grain-based liquor) which is cool in nature is traditionally used to 'cool the blood' and reduce the swelling of sores and abscesses.

AIM OF STUDY

The present study aimed to examine the effect and mechanism of DSI in LAD induced heart injury.

MATERIALS AND METHODS

One day after LAD surgery, adult male Sprague-Dawley rats were randomized to 3 groups: MI group; DSI group (1.5ml/kg/d, intramuscular); and Valsartan group (10mg/kg/d, intragastric). Echocardiography and hemodynamic measurements (Pressure-Volume loop) were performed to evaluate cardiac function. Pathological methods (Masson, and Sirus red staining) were used to check myocardial fibrosis. Western blotting assay was used to detect the protein expression of MMP-2. RT-PCR was used to detect the gene expression of MMP-9, MPO, iNOS, Bcl-2 and Bax.

RESULTS

DSI administration to LAD rats resulted in improved cardiac functions, hemodynamic parameters and normalized ventricular mass. Furthermore, DSI-treated group demonstrated potential regulation of myocardial collagen I and III deposition associated with MMP-2 expression. Also, DSI administration decreased gene expression of iNOS, MPO and MMP-9, and increased Bcl-2/Bax ratio.

CONCLUSION

Myocardial fibrosis, cardiac hypertrophy, hemodynamic deterioration as well as systolic and diastolic dysfunctions which characterize a failing hearts were significantly prevented by DSI. Our study may provide future directions to focus on the anti-hypertrophic mechanisms of DSI and pathological roles played by MMP-2 in myocardial hypertrophy. Meanwhile, DSI also performed the effect of anti-inflammation by the way of decreasing iNOS and MPO. The way Danshen Injection increasing Bcl-2/Bax presented the possibility that it may has the effect of inhibiting cell death.

Matrix metalloproteinases in exercise and obesity

Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endoproteinases that have the ability to break down extracellular matrix. The large range of MMPs’ functions widens their spectrum of potential role as activators or inhibitors in tissue remodeling, cardiovascular diseases, and obesity. In particular, MMP-1, -2, and -9 may be associated with exercise and obesity. Thus, the current study reviewed the effects of different types of exercise (resistance and aerobic) on MMP-1, -2, and -9. Previous studies report that the response of MMP-2 and -9 to resistance exercise is dependent upon the length of exercise training, since long-term resistance exercise training increased both MMP-2 and -9, whereas acute bout of resistance exercise decreased these MMPs. Aerobic exercise produces an inconsistent result on MMPs, although some studies showed a decrease in MMP-1. Obesity is related to a relatively lower level of MMP-9, indicating that an exercise-induced increase in MMP-9 may positively influence obesity. A comprehensive understanding of the relationship between exercise, obesity, and MMPs does not exist yet. Future studies examining the acute and chronic responses of these MMPs using different subject models may provide a better understanding of the molecular mechanisms that are associated with exercise, obesity, and cardiovascular disease.

Matrix metalloproteinases are possible targets in monocrotaline-induced pulmonary hypertension: investigation of anti-remodeling effects of alagebrium and everolimus

Objective:

In our study, sildenafil alone and everolimus or alagebrium in combination with sildenafil were investigated in terms of their additional therapeutic and anti-remodeling activity in monocrotaline-induced pulmonary hypertension (PH) model in rats. In particular, the inter-relationships between PH and matrix metalloproteinases (MMPs) were investigated.

Methods:

The pulmonary artery responses of male Sprague Dawley rats were recorded using myography, and the quantities and activities of MMPs were analyzed in homogenates of the pulmonary arteries and lungs by enzyme-linked immunosorbent assays, activity assays, and gelatin zymography techniques.

Results:

Our results indicated that the therapeutic effects of sildenafil were accompanied by its suppressor effects on MMP activity. It was also shown that everolimus or alagebrium in combination with sildenafil showed additional regulatory effects on MMPs as well as functional responses on pulmonary artery pressure. Therefore, the enzymes in the MMP superfamily are likely to be target molecules for the treatment of PH.

Conclusion:

In conclusion, MMPs were involved in the pathogenesis of PH, and our results suggested that the addition of everolimus or alagebrium to sildenafil therapy may be beneficial in PH. Our results indicated that agents that limit pulmonary vascular hypertrophy and inflammation via their anti-remodeling effects significantly ameliorate mortality and morbidity in PH.

Platelet Extracellular Regulated Protein Kinase 5 Is a Redox Switch and Triggers Maladaptive Platelet Responses and Myocardial Infarct Expansion

BACKGROUND

Platelets have a pathophysiologic role in the ischemic microvascular environment of acute coronary syndromes. In comparison with platelet activation in normal healthy conditions, less attention is given to mechanisms of platelet activation in diseased states. Platelet function and mechanisms of activation in ischemic and reactive oxygen species-rich environments may not be the same as in normal healthy conditions. Extracellular regulated protein kinase 5 (ERK5) is a mitogen-activated protein kinase family member activated in hypoxic, reactive oxygen species-rich environments and in response to receptor-signaling mechanisms. Prior studies suggest a protective effect of ERK5 in endothelial and myocardial cells after ischemia. We present evidence that platelets express ERK5 and that platelet ERK5 has an adverse effect on platelet activation via selective receptor-dependent and receptor-independent reactive oxygen species-mediated mechanisms in ischemic myocardium.

METHODS AND RESULTS

Using isolated human platelets and a mouse model of myocardial infarction (MI), we found that platelet ERK5 is activated post-MI and that platelet-specific ERK5(-/-) mice have less platelet activation, reduced MI size, and improved post-MI heart function. Furthermore, the expression of downstream ERK5-regulated proteins is reduced in ERK5(-/-) platelets post-MI.

CONCLUSIONS

ERK5 functions as a platelet activator in ischemic conditions, and platelet ERK5 maintains the expression of some platelet proteins after MI, leading to infarct expansion. This demonstrates that platelet function in normal healthy conditions is different from platelet function in chronic ischemic and inflammatory conditions. Platelet ERK5 may be a target for acute therapeutic intervention in the thrombotic and inflammatory post-MI environment.