PEDF improves cardiac function in rats with acute myocardial infarction via inhibiting vascular permeability and cardiomyocyte apoptosis

PEDF and 34-mer peptide inhibit cardiac microvascular endothelial cell ferroptosis via Nrf2/HO-1 signalling in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) represents a critical pathology in acute myocardial infarction (AMI), which is characterized by high mortality and morbidity. Cardiac microvascular dysfunction contributes to MIRI, potentially culminating in heart failure (HF). Pigment epithelium-derived factor (PEDF), which belongs to the non-inhibitory serpin family, exhibits several physiological effects, including anti-angiogenesis, anti-inflammatory and antioxidant properties. Our study aims to explore the impact of PEDF and its functional peptide 34-mer on both cardiac microvascular perfusion in MIRI rats and human cardiac microvascular endothelial cells (HCMECs) injury under hypoxia reoxygenation (HR). It has been shown that MIRI is accompanied by ferroptosis in HCMECs. Furthermore, we investigated the effect of PEDF and its 34-mer, particularly regarding the Nrf2/HO-1 signalling pathway. Our results demonstrated that PEDF 34-mer significantly ameliorated cardiac microvascular dysfunction following MIRI. Additionally, they exhibited a notable suppression of ferroptosis in HCMECs, and these effects were mediated through activation of Nrf2/HO-1 signalling. These findings highlight the therapeutic potential of PEDF and 34-mer in alleviating microvascular dysfunction and MIRI. By enhancing cardiac microvascular perfusion and mitigating endothelial ferroptosis, PEDF and its derivative peptide represent promising candidates for the treatment of AMI.

Influence of a Passive Tilt Test on the Proteomic Composition of the Blood of Healthy Humans

In order to identify changes in the blood proteome of healthy volunteers after passive tilt test carried out on day 19 of head-down bed rest, a chromato-mass-spectrometric analysis of samples of dried blood spots was carried out. It was revealed that the body's response to the tilt test was characterized by a decrease in the level of HDL and kininogen-1. After the tilt test, we observed an increase in the level of vimentin, vitamin K-dependent protein C, Wnt signaling pathway proteins, proteins involved in autophagy and adaptive immune response, focal adhesion proteins, vascular damage marker S100A8, PEDF regulator, and some proteins of the heart: cardiac actin ACTC1 and transcription factor GATA4. The obtained results lay the foundation for future research in the framework of identifying the risks of developing cardiovascular changes in astronauts after space flights.

Potential application value of pigment epithelium-derived factor in sensorineural hearing loss

The inner ear is a complex and precise auditory perception system responsible for receiving and converting sound signals into neural signals, enabling us to perceive and understand sound. However, the occurrence and development of inner ear diseases and auditory disorders, such as sensorineural hearing loss, remain a global problem. In recent years, there has been increasing research on the treatment of inner ear diseases and auditory regeneration. Among these treatments, pigment epithelium-derived factor (PEDF), as a multifunctional secretory protein, exhibits diverse biological activities and functions through various mechanisms, and has shown potential applications in the inner ear. This minireview comprehensively evaluates the performance of PEDF in sensorineural hearing loss in inner ear and its potential targets and therapeutic prospects.

Roles of pigment epithelium-derived factor in cardiomyocytes: implications for use as a cardioprotective therapeutic

OBJECTIVES

Cardiovascular diseases are the leading cause of death worldwide, with patients having limited options for treatment. Pigment epithelium-derived factor (PEDF) is an endogenous multifunctional protein with several mechanisms of action. Recently, PEDF has emerged as a potential cardioprotective agent in response to myocardial infarction. However, PEDF is also associated with pro-apoptotic effects, complicating its role in cardioprotection. This review summarises and compares knowledge of PEDF's activity in cardiomyocytes with other cell types and draws links between them. Following this, the review offers a novel perspective of PEDF's therapeutic potential and recommends future directions to understand the clinical potential of PEDF better.

KEY FINDINGS

PEDF's mechanisms as a pro-apoptotic and pro-survival protein are not well understood, despite PEDF's implication in several physiological and pathological activities. However, recent evidence suggests that PEDF may have significant cardioprotective properties mediated by key regulators dependent on cell type and context.

CONCLUSIONS

While PEDF's cardioprotective activity shares some key regulators with its apoptotic activity, cellular context and molecular features likely allow manipulation of PEDF's cellular activity, highlighting the importance of further investigation into its activities and its potential to be applied as a therapeutic to mitigate damage from a range of cardiac pathologies.

Suppression of lysosomal-associated protein transmembrane 5 ameliorates cardiac function and inflammatory response by inhibiting the nuclear factor-kappa B (NF-κB) pathway after myocardial infarction in mice

Myocardial infarction (MI) as the remarkable presentation of coronary artery disease is still a reason for morbidity and mortality in worldwide. Lysosomal-associated protein transmembrane 5 (LAPTM5) is a lysosomal-related protein found in hematopoietic tissues and has been confirmed as a positive regulator of pro-inflammatory pathways in macrophages. However, the role of LAPTM5 in MI remains unknown. In this study, we found that both mRNA and protein expression levels of LAPTM5 were significantly elevated in MI mice. Suppression of LAPTM5 in myocardial tissues decreased cardiac fibrosis and improved cardiac function after MI. At the molecular level, downregulated LAPTM5 dramatically suppressed the macrophage activation and inflammatory response via inhibiting the activation of the nuclear factor-kappa B (NF-κB) pathway. Collectively, suppression of LAPTM5 in myocardial tissues inhibits the pro-inflammatory response and the cardiac dysfunction caused by MI. This study indicated that LAPTM5 as a pro-inflammatory factor plays a crucial role in MI disease.

Screening of anti-heart failure active compounds from fangjihuangqi decoction in verapamil-induced zebrafish model by anti-heart failure index approach

Heart failure is the end stage of various cardiovascular diseases. Fangjihuangqi Decoction (FJHQD) is a famous traditional Chinese medicine (TCM) formula, which is clinically effective in the treatment of chronic heart failure. However, the anti-heart failure ingredients of FJHQD have not been clarified, and the related mechanisms of action are rarely studied. In the present study, through quantification analysis of heart rate and ventricular area changes, a heart failure model and cardiac function evaluation system in cardiomyocytes-labelled Tg (cmlc2: eGFP) transgenic zebrafish larvae were constructed, and the anti-heart failure index (AHFI) that can comprehensively evaluate the cardiac function of zebrafish was proposed. Based on this model, FJHQD, its mainly botanical drugs, components and ingredients were evaluated for the anti-heart failure effects. The results showed that FJHQD and its botanical drugs exhibited potent anti-heart failure activity. Furthermore, total alkaloids from Stephania tetrandra S. Moore, total flavonoids from Astragalus mongholicus Bunge and total flavonoids from Glycyrrhiza uralensis Fisch. ex DC. were identified to be the main components exerting the anti-heart failure activity of FJHQD. Then, we screened the main ingredients of these components, and glycyrrhizic acid, licochalcone A and calycosin were found to exhibit excellent cardioprotective effects. Finally, we found that FJHQD, glycyrrhizic acid, licochalcone A and calycosin may improve cardiac function in zebrafish by regulating oxidative stress, inflammatory response and apoptosis-related pathways. Taken together, our findings offer biological evidences toward the anti-heart failure effect of FJHQD, and provide guidance for the clinical application of FJHQD.

LncRNA FGD5-AS1 reduces cardiomyocyte apoptosis and inflammation by modulating Akt and miR-223-3p expression

OBJECTIVES

Long non-coding RNAs (lncRNAs) are known to be involved in heart development and function. In this study, we aimed to explore the effect of the lncRNA FGD5 antisense RNA 1 (FGD5-AS1) on acute myocardial infarction (AMI) by targeting miR-223-3p.

METHODS

An AMI model was established both in vivo and in vitro. The levels of FGD5-AS1, miR-223-3p and inflammatory factors were detected by real-time quantitative reverse transcription PCR. Cardiomyocyte apoptosis was assessed using TdT-mediated dUTP nick-end labeling assay. The protein levels of cleaved caspase-3, Bcl-2 and Bax were examined using Western blot. Cardiac function was evaluated using hemodynamic analysis and hematoxylin-eosin and Masson's trichrome staining. In addition, an underlying competitive endogenous RNA mechanism was revealed by bioinformatics analysis, dual-luciferase reporter assay and rescue experiments.

RESULTS

We found decreased expression of FGD5-AS1 in AMI. Furthermore, FGD5-AS1 expression significantly decreased the infarct size, improved cardiac performance and attenuated cardiac fibrosis by reducing myocardial apoptosis and inflammation. miR-223-3p was a direct target of FGD5-AS1. Moreover, miRNA-223-3p directly downregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes. Further experiments demonstrated that FGD5-AS1 modulated Akt activity to reduce myocardial injury through miR-223-3p.

CONCLUSION

The FGD5-AS1/miR-223-3p/Akt pathway is involved in AMI, suggesting that FGD5-AS1 may act as a potential biomarker and therapeutic target for AMI.

Pigment epithelium-derived factor maintains tight junction stability after myocardial infarction in rats through inhibition of the Wnt/β-catenin signaling pathway

PURPOSE

The impairment of the coronary microcirculatory barrier caused by acute myocardial infarction (AMI) is closely related to poor prognosis. Recently, pigment epithelial-derived factor (PEDF) has been proven to be a promising cardiovascular protective drug. In this study, we demonstrated the protective role of PEDF in endothelial tight junctions (TJs) and the vascular barrier in AMI.

MATERIALS AND METHODS

2, 3, 5-triphenyltetrazolium chloride (TTC), echocardiography and immunofluorescence staining were used to observe the size of infarcted myocardium area and cardiac function in myocardial tissue, and the distribution of tight junction proteins in human coronary endothelial cells (HCAEC). Dextran leakage assay and Transwell were used to assess the extent of vascular and HCAEC leakage. PCR and Western blot were used to detect tight junction-related mRNA and protein, and signaling pathway protein expression.

RESULTS

PEDF effectively reduced the infarction area and improved cardiac function in AMI rats, and lowered the leakage in AMI rats' angiocarpy and oxygen-glucose deprivation (OGD)-treated HCAEC. Furthermore, PEDF upregulated the expression of TJ mRNA and proteins in vivo and vitro. Mechanistically, PEDF inhibited the expression of phosphorylated low-density lipoprotein receptor-related protein 6 (p-LRP6) and active β-catenin under OGD, thus suppressing the activation of the classical Wnt pathway.

CONCLUSIONS

These novel findings demonstrated that PEDF maintained the expression of TJ proteins and endothelial barrier integrity by inhibiting the classical Wnt pathway during AMI.

Remifentanil protects heart from myocardial ischaemia/reperfusion (I/R) injury via miR-206-3p/TLR4/NF-κB signalling axis

OBJECTIVES

Myocardial I/R injury is one of the most serious complications after reperfusion therapy in patients with myocardial infarction. Remifentanil has been found to protect the heart against I/R injury. However, its underlying mechanism remains uncertain in myocardial I/R injury.

METHODS

The myocardial I/R injury rat model was established by 30 min of ischaemia followed by 24 h of reperfusion. The animal model was evaluated by the levels of TC, ALT and AST and H&E staining. The binding of miR-206-3p and TLR4 was predicted and verified using TargetScan software, luciferase reporter and RNA pull-down assays. The functional role and mechanism of remifentanil were identified by ultrasonic echocardiography, oxidative stress markers, H&E, Masson and TUNEL staining and western blot.

KEY FINDINGS

The rat myocardial I/R injury model displayed a significantly high level of TC, ALT, AST, TLR4, p-IκBα and p-p65 and the presence of disorganized cells and inflammatory cell infiltration. The model also showed increased levels of LVEDD, LVESD, MDA, fibrosis and apoptosis and decreased levels of EF, FS, SOD and GSH, which were reversed with remifentanil treatment. Knockdown of miR-206-3p damaged cardiac function and aggravated oxidative stress. miR-206-3p could directly bind to TLR4. TLR4 overexpression destroyed cardiac function, exacerbated oxidative stress, increased levels of p-IκBα and p-p65 and aggravated pathology manifestation affected by remifentanil.

CONCLUSIONS

Our results elucidated that remifentanil alleviated myocardial I/R injury by miR-206-3p/TLR4/NF-κB signalling axis.

Strategies to Attenuate Myocardial Infarction and No-Reflow Through Preservation of Vascular Integrity by Pigment Epithelium-Derived Factor

The phenomenon of no-reflow seriously limits the therapeutic value of coronary recanalization and leads to poor prognosis. Recent studies have demonstrated the potential role of pigment epithelium-derived factor (PEDF) in stabilizing endothelial cell junction, reducing vascular permeability and maintaining a quiescent vasculature. In this study, intramyocardial gene delivery was performed 5 days before the acute myocardial infarction/recanalization experiment in male rats. Positron emission tomography perfusion imaging with ¹³N-NH₃ indicated PEDF to promote microvascular reperfusion significantly 4 h postcoronary occlusion. PEDF was observed to maintain the stability of endothelial adherens junctions (AJs), thus preventing the occurrence of no-reflow. PEDF reduced the hypoxia-induced vascular endothelial (VE)-cadherin endocytosis through PEDF/LR/Src/VE-cadherin S665 axis in vitro, which was remarkably observed to maintain endothelial AJs. Generally, PEDF might function as a relevant target for therapeutic vasculoprotection by way of regulating the phosphorylation level of VE-cadherin according to our data, thus being crucial for preventing no-reflow.

Pigment epithelium-derived factor, a novel decidual natural killer cells-derived factor, protects decidual stromal cells via anti-inflammation and anti-apoptosis in early pregnancy

STUDY QUESTION

What is the role of pigment epithelium-derived factor (PEDF) from decidual natural killer (dNK) cells during early pregnancy?

SUMMARY ANSWER

PEDF from dNK cells limits the lipopolysaccharide (LPS)-induced apoptosis and inflammation of decidual stromal cells (DSCs) to maintain DSCs homoeostasis and immune balance at the maternal-foetal interface during early pregnancy.

WHAT IS KNOWN ALREADY

dNK cells, which secrete PEDF, play critical roles during pregnancy via a series of key regulators. PEDF, a multifunctional endogenous glycoprotein, exhibits a wide range of biological actions upon angiogenesis, inflammation, metabolic homoeostasis, immunomodulation etc., providing potential clinical applications.

STUDY DESIGN, SIZE, DURATION

Natural killer (NK) cells from decidua and peripheral blood as well as DSCs isolated from normal pregnancy (NP) during the first trimester (6-10 weeks) and the matched patients suffering recurrent miscarriage (RM) were studied. RNA-sequencing analysis of dNK cells was performed to screen for potential key genes involved in RM. The expression of PEDF in dNK cells in NP and RM was examined. A coculture system with LPS-stimulated DSCs and NK cell supernatants derived from NP or RM was established to explore the regulatory mechanisms of PEDF at the maternal-foetal interface.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peripheral blood and decidual tissues were obtained from women with NP (n = 61) and RM (n = 21). The expression levels of PEDF in NK cells and its receptor (PEDFR) on DSCs were analysed using flow cytometry, western blot and immunohistochemistry. Purified peripheral natural killer (pNK) cells were cocultured with DSCs or trophoblast cells or a combination of both cell types, and PEDF expression in pNK cells was then examined by flow cytometry. DSCs were treated with LPS, an outer-membrane component of Gram-negative bacteria, thereby mimicking an enhanced inflammatory status within decidua, and were cocultured with dNK cell supernatants from NP or RM. In the coculture system, plasmids expressing short hairpin RNA were used to silence PEDFR on DSCs and block the PEDF/PEDFR interaction. Inflammatory cytokines and apoptosis of DSCs treated as described above were assessed by flow cytometry. Western blotting was performed, and the specific signal pathway inhibitors were used to determine downstream PEDF/PEDFR signalling in early decidua.

MAIN RESULTS AND THE ROLE OF CHANCE

Markedly higher RNA (P < 0.001) and protein expression of PEDF (P < 0.01) was detected in normal dNK cells when compared with pNK cells. Compared with pNK cells cultured alone, PEDF expression in pNK cells was elevated after coculture with DSCs (P < 0.01) or trophoblast cells (P < 0.001). The increased pro-inflammatory cytokine, tumour necrosis factor-α and apoptosis of DSCs following LPS stimulation were suppressed by recombinant human PEDF (P < 0.001) or the supernatant of dNK cells derived from NP (P < 0.001). However, these effects were somewhat abrogated when the PEDF/PEDFR interaction was blocked with PEDFR short hairpin sRNA (P < 0.01). Furthermore, dNK cell-derived PEDF protected DSCs from LPS-induced inflammation via inhibition of nuclear factor kappa-B activation, while also protecting DSCs from LPS-induced apoptosis via promotion of extracellular signal-regulated kinase expression. Compared with NP, both significantly decreased PEDF RNA (P < 0.001) and protein expression (P < 0.001) in dNK cells, but not in pNK cells (P > 0.05), were detected in women with RM. PEDFR on DSCs was also decreased within RM compared with that within NP (P < 0.001). As a result, dNK cell-mediated anti-inflammation (P < 0.01) and anti-apoptosis (P < 0.05) for protection of LPS-treated DSCs was attenuated in patients suffering from RM.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

We cannot exclude the possibility that the differences in amounts of PEDF and its receptor in tissue from NP versus RM women could be caused by the miscarriage event in women with RM. Our experiments only involved human samples investigated in vitro. Experiments in animal models and human study cohorts are still needed to confirm these findings and further clarify the role of PEDF-PEDFR in NP and/or RM.

WIDER IMPLICATIONS OF THE FINDINGS

To the best of our knowledge, this is the first study to demonstrate PEDF expression and function at the maternal-foetal interface in the first trimester, providing further evidence that PEDF exhibits functional diversity and has great potential for clinical application(s). The findings of selectively high expression of PEDF in normal dNK cells and the PEDF-mediated role of dNK cells during NP and RM help to further elucidate the immune mechanisms behind RM.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Basic Research Programme of China (2017YFC1001403 and 2015CB943300), Nature Science Foundation from National Nature Science Foundation of China (NSFC; 31970859, 81630036, 81501334, 91542116, 31570920, 81490744 and 31171437), the Innovation-oriented Science and Technology Grant from NHC Key Laboratory of Reproduction Regulation (CX2017-2), the Programme of Shanghai Academic/Technology Research Leader (17XD1400900) and the Key Project of Shanghai Basic Research from Shanghai Municipal Science and Technology Commission (STCSM; 12JC1401600). None of the authors has any conflict of interest to declare.

Tumour necrosis factor receptor-associated factors: interacting protein with forkhead-associated domain inhibition decreases inflammatory cell infiltration and cardiac remodelling after acute myocardial infarction

OBJECTIVES

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Post-AMI cardiac remodelling is closely related to the prognosis of AMI. The excess inflammatory responses could promote cardiac remodelling. Tumour necrosis factor receptor-associated factor-interacting protein with forkhead-associated domain (TIFA) has been identified as a nuclear factor (NF)-κB activator, which plays a key role in the activation of the NF-κB signalling pathway. The goal of this research was to investigate the expression and the underlying mechanism of TIFA in an AMI mouse model.

METHODS

The AMI mouse model was induced by ligation of the left coronary artery. TIFA and NF-κB knockdown were established by lentivirus transduction. The expression levels of associated proteins were analysed by a western blot or an enzyme-linked immunosorbent assay. Histological characteristics were evaluated by haematoxylin-eosin staining.

RESULTS

The TIFA level was elevated in our AMI mouse model. The production of interleukin-1β and tumour necrosis factor-α increased markedly in the mice with AMI. TIFA knockdown inhibited the infiltration of inflammatory cells, production of pro-inflammatory mediators (interleukin-1β and tumour necrosis factor-α), NF-κB activation and cardiac remodelling (matrix metallopeptidase 9) post-AMI. In addition, NF-κB knockdown could also alleviate cardiac remodelling after AMI.

CONCLUSIONS

The preceding results indicated that TIFA inhibition could ameliorate cardiac remodelling after AMI partly through inactivation of NF-κB. This study provides insights into further research of cardiac remodelling and AMI from bench to clinic.

Effects of carbon nanotube-mediated Caspase3 gene silencing on cardiomyocyte apoptosis and cardiac function during early acute myocardial infarction

RNA interference (RNAi) technology can achieve efficient and specific silencing of Caspase3 gene expression, thus providing new options for anti-apoptosis treatment. However, delivering siRNA to specific cells and tissues in the body is a significant challenge. Therefore, we aim to construct a functionalized single-walled carbon nanotube (F-CNT) bound to siRNA from Caspase3. The obtained gene transfer carrier F-CNT-siCas3 not only demonstrated a good water solubility and biocompatibility, but also had a high transfection efficiency of up to 82%, which significantly downregulated the expression level of the Caspase3 gene miRNA and protein in primary cardiomyocytes. Furthermore, it was verified by in vivo experiments that Caspase3 gene silencing had obvious protective effects on myocardial cell apoptosis, ventricular remodeling, and cardiac function in Sprague-Dawley (SD) rats after coronary artery ligation. This study may provide an important theoretical basis for the application of F-CNT in vivo siRNA gene therapy to treat cardiovascular diseases.

Effect of high-intensity interval training on cardiac structure and function in rats with acute myocardial infarct

BACKGROUND

Exercise training is beneficial for cardiac rehabilitation. Nevertheless, few study focused on the role of high-intensity interval training (HIIT) in cardiac repair. The current study aimed to elucidate the effect of HIIT on cardiac rehabilitation and the involved mechanisms after acute myocardial infarction (MI).

METHODS

A total of 65 male rats underwent coronary ligation or sham operation and were randomly assigned to 4 groups: sham (n = 10), sedentary (MI-Sed, n = 12), moderate-intensity continuous training (MI-MCT, n = 12) and HIIT (MI-HIIT, n = 12). One week after MI induction, adaptive training starts follow by formal training. After the experiment, cardiac functions were determined by echocardiography and hemodynamic measurements. Changes in infarct size, collagen accumulation, myofibroblasts, angiogenesis, inflammation level, endothelin-1 (ET-1), and renin-angiotensin-aldosterone system (RAAS) activities were measured. Data were analyzed by one-way ANOVA.

RESULTS

After MI, cardiac structure and function were significantly deteriorated. However, post-MI HIIT for 8 weeks had significantly ameliorated left ventricular end-diastolic pressure (LVEDP), LV systolic pressure (LVSP), and maximum peak velocities of relaxation (-dP/dtmax). Moreover, it preserved cardiac functions, reduced infarct size, protected the myocardium structure, increased angiogenesis and decreased the myofibroblasts and collagen accumulation. HIIT for 4 weeks had no effect on LVEDP, -dP/dtmax, infarct size and angiogenesis. Additionally, it induced inflammation response and repressed ET-1 and RAAS activities were found in myocardium and peripheral circulation after HIIT.

CONCLUSION

Our results suggested that post-MI HIIT had a positive role in cardiac repair, which might be linked with the induction of inflammation and inhibition of ET-1 and RAAS activities.

PEDF promotes the repair of bone marrow endothelial cell injury and accelerates hematopoietic reconstruction after bone marrow transplantation

Background

Preconditioning before bone marrow transplantation such as irradiation causes vascular endothelial cells damage and promoting the repair of damaged endothelial cells is beneficial for hematopoietic reconstitution. Pigment epithelium-derived factor (PEDF) regulates vascular permeability. However, PEDF’s role in the repair of damaged endothelial cells during preconditioning remains unclear. The purpose of our study is to investigate PEDF’s effect on preconditioning-induced damage of endothelial cells and hematopoietic reconstitution.

Methods

Damaged endothelial cells induced by irradiation was co-cultured with hematopoietic stem cells (HSC) in the absence or presence of PEDF followed by analysis of HSC number, cell cycle, colony formation and differentiation. In addition, PEDF was injected into mice model of bone marrow transplantation followed by analysis of bone marrow injury, HSC number and peripheral hematopoietic reconstitution as well as the secretion of cytokines (SCF, TGF-β, IL-6 and TNF-α). Comparisons between two groups were performed by student t-test and multiple groups by one-way or two-way ANOVA.

Results

Damaged endothelial cells reduced HSC expansion and colony formation, induced HSC cell cycle arrest and apoptosis and promoted HSC differentiation as well as decreased PEDF expression. Addition of PEDF increased CD144 expression in damaged endothelial cells and inhibited the increase of endothelial permeability, which were abolished after addition of PEDF receptor inhibitor Atglistatin. Additionally, PEDF ameliorated the inhibitory effect of damaged endothelial cells on HSC expansion in vitro. Finally, PEDF accelerated hematopoietic reconstitution after bone marrow transplantation in mice and promoted the secretion of SCF, TGF-β and IL-6.

Conclusions

PEDF inhibits the increased endothelial permeability induced by irradiation and reverse the inhibitory effect of injured endothelial cells on hematopoietic stem cells and promote hematopoietic reconstruction.

Pigment Epithelium-Derived Factor Increases Native Collateral Blood Flow to Improve Cardiac Function and Induce Ventricular Remodeling After Acute Myocardial Infarction

Background

We previously found that the structural defects of the coronary collateral microcirculation reserve (CCMR) prevent these preformed collateral vessels from continuously delivering the native collateral blood and supporting the ischemic myocardium in rats. Here, we tested whether these native collaterals can be remodeled by artificially increasing pigment epithelium–derived factor (PEDF) expression and demonstrated the mechanism for this stimulation.

Methods and Results

We performed intramyocardial gene delivery (PEDF‐lentivirus, 2×10⁷ TU) along the left anterior descending coronary artery to artificially increase the expression of PEDF in the tissue of the region for 2 weeks. By blocking the left anterior descending coronary artery, we examined the effects of PEDF on native collateral blood flow and CCMR. The results of positron emission tomography perfusion imaging showed that PEDF increased the native collateral blood flow and significantly inhibited its decline during acute myocardial infarction. In addition, the number of CCMR vessels decreased and the size increased. Similar results were obtained from in vitro experiments. We tested whether PEDF induces CCMR remodeling in a fluid shear stress–like manner by detecting proteins and signaling pathways that are closely related to fluid shear stress. The nitric oxide pathway and the Notch‐1 pathway participated in the process of CCMR remodeling induced by PEDF.

Conclusions

PEDF treatment activates the nitric oxide pathway, and the Notch‐1 pathway enabled CCMR remodeling. Increasing the native collateral blood flow can promote the ventricular remodeling process and improve prognosis after acute myocardial infarction.

Pigment Epithelial-Derived Factor Deficiency Accelerates Atherosclerosis Development via Promoting Endothelial Fatty Acid Uptake in Mice With Hyperlipidemia

Background

Endothelial cell injury, induced by dyslipidemia, is the initiation of atherosclerosis, resulting in an imbalance in endothelial fatty acid (FA) transport. Pigment epithelial‐derived factor (PEDF) is an important regulator in lipid metabolism. We hypothesized that PEDF is involved in endothelium‐mediated FA uptake under hyperlipidemic conditions.

Methods and Results

Circulating PEDF levels were higher in patients with atherosclerotic cardiovascular disease than in normal individuals. However, decreasing trends of serum PEDF levels were confirmed in both wild‐type and apolipoprotein E–deficient mice fed a long‐term high‐fat diet. Apolipoprotein E–deficient/PEDF‐deficient mice were generated by crossing PEDF‐deficient mice with apolipoprotein E–deficient mice, and then mice were fed with 24, 36, or 48 weeks of high‐fat diet. Greater increases in body fat and plasma lipids were displayed in PEDF‐deficient mice. In addition, PEDF deficiency in mice accelerated atherosclerosis, as evidenced by increased atherosclerotic plaques, pronounced vascular dysfunction, and increased lipid accumulation in peripheral tissues, whereas injection of adeno‐associated virus encoding PEDF exerted opposite effects. Mechanistically, PEDF inhibited the vascular endothelial growth factor B paracrine signaling by reducing secretion of protein vascular endothelial growth factor B in peripheral tissue cells and decreasing expression of its downstream targets in endothelial cells, including its receptors (namely, vascular endothelial growth factor receptor‐1 and neuropilin‐1), and FA transport proteins 3 and 4, to suppress endothelial FA uptake, whereas PEDF deletion in mice activated the vascular endothelial growth factor B signaling pathway, thus causing markedly increased lipid accumulation.

Conclusions

Decreasing expression of PEDF aggravates atherosclerosis by significantly impaired vascular function and enhanced endothelial FA uptake, thus exacerbating ectopic lipid deposition in peripheral tissues.

MicroRNA-155 inhibition attenuates endoplasmic reticulum stress-induced cardiomyocyte apoptosis following myocardial infarction via reducing macrophage inflammation

Endoplasmic reticulum stress (ERS)-induced cardiomyocyte apoptosis plays an important role in the pathological process following myocardial infarction (MI). Macrophages that express microRNA-155 (miR-155) mediate cardiac inflammation, fibrosis, and hypertrophy. Therefore, we investigated if miR-155 regulates ERS-induced cardiomyocyte apoptosis after MI using a mouse model, lipopolysaccharide (LPS)-induced rat bone marrow derived macrophages (BMDMs)and hypoxia-induced neonatal rat cardiomyocytes (NRCMs). In vivo, miR-155 levelswere significantly higher in the MI group compared to the sham group. MI increasedmacrophage infiltration, nuclear factor-κB (NF-κB) activation, ERS induced-apoptosis, and SOCS1 expression, all of which were attenuated by the miR-155 antagomir, with the exception of SOCS1 expression. Additionally, post-MI cardiac dysfunction was significantly improved by miR-155 inhibition. In vitro, LPS upregulated miR-155 expression in BMDMs, and the miR-155 antagomir decreased LPS-induced macrophage inflammation and NF-κB pathway activation, but increased expression of SOCS1. Hypoxia increased NF-κB pathway activation, ERS marker expression, and apoptosis in NRCMs. Interestingly, conditioned medium from LPS-induced macrophages in combination with the miR-155 antagomir decreased, while the miR-155 agomir increased, the hypoxia-induced effects in NRCM's. The miR-155 agomir effects were reversed by inhibiting the NF-κB pathway in cardiomyocytes. Moreover, SOCS1 knockdown in LPS-induced macrophages promoted NF-κB pathway activation and ERS-induced cardiomyocyte apoptosis in the hypoxia-induced NRCMs, but the SOCS1-siRNA-induced effects were markedly decreased by miR-155 antagomir treatment. These data suggest that miR-155 inhibition attenuates ERS-induced cardiomyocyte apoptosis after MI via reducing macrophage inflammation through the SOCS1/NF-κB pathway.

Association of Pigment Epithelium Derived Factor With von Willebrand Factor and Plasminogen Activator Inhibitor 1 in Patients With Type 2 Diabetes

To compare circulating pigment epithelium derived factor (PEDF) levels in type 2 diabetes patients (T2D) with and without metabolic syndrome (MetS+/-) to healthy controls and assess PEDF association with plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF) as markers of endothelial dysfunction. Fifty T2D individuals and forty healthy controls were included. PEDF, PAI-1, vWF, anthropological parameters, lipids, and markers of insulin resistance were investigated in all subjects. Compared to controls only MetS+ diabetics had higher PEDF levels [14.2 (10.2-16.0) mg/l vs. 11.1 (8.6-14.4) mg/l; p<0.05]. PEDF significantly correlated: positively with body mass index (ρ=0.25), smoking (ρ=0.21), C-reactive protein (ρ=0.22), triglycerides (ρ=0.38), non-HDL-cholesterol (ρ=0.39), apolipoprotein B (ρ=0.38), fasting glucose (ρ=0.22), glycated hemoglobin (ρ=0.24), C-peptide (ρ=0.28), insulin (ρ=0.26); and negatively with HDL-cholesterol (ρ=-0.42) and apolipoprotein A1 (ρ=-0.27). Independent association of PEDF with vWF in T2DMetS- subjects was found. Significantly elevated PEDF in T2DMet+ patients and its association with adverse metabolic profile confirmed PEDF as a marker of insulin resistance. Negative independent association of PEDF with vWF in T2DMetS- patients may reveal its angio-protective role.

PEDF decreases cardiomyocyte edema during oxygen‑glucose deprivation and recovery via inhibiting lactate accumulation and expression of AQP1

Myocardial edema is divided into cellular edema and interstitial edema; however, the dynamic change of cardiomyocyte edema has not been described in detail. Pigment epithelium-derived factor (PEDF) is known for its protective effects on ischemic cardiomyocytes; however, the association between PEDF and cardiomyocyte edema remains to be fully elucidated. In the present study, rat neonatal left ventricular cardiomyocytes were isolated and treated with oxygen-glucose deprivation (OGD) and recovery. During OGD and recovery, the cardiomyocytes exhibited significant edema following 30 min of OGD (OGD 30 min) and OGD 30 min with recovery for 6 h. PEDF significantly decreased the lactate content and extracellular acidification rate of the OGD-treated cardiomyocytes, thereby reducing cellular osmotic gradients and preventing the occurrence of cell edema. In addition, the glycolytic agonist, fructose-1, 6-diphosphate, eliminated the effect of PEDF on inhibiting edema in the OGD-treated cardiomyocytes. Furthermore, PEDF reduced the protein and mRNA expression of aquaporin 1 (AQP1), and thus downregulated cardiomyocyte edema during the OGD/recovery period. The addition of AQP1 agonist, arginine vasopressin, inhibited the inhibitory effect of PEDF on cardiomyocyte edema during OGD/recovery. In conclusion, the present study revealed a novel mechanism for the regulation of cardiomyocyte edema by PEDF involving lactate levels and the expression of AQP1 during OGD/recovery. The reduction of lactate content during OGD was associated with a decrease in the protein level of AQP1 during OGD/recovery; therefore, PEDF decreased cardiomyocyte edema and cellular apoptosis, prolonging the viability of the cells.

PEDF increases GLUT4-mediated glucose uptake in rat ischemic myocardium via PI3K/AKT pathway in a PEDFR-dependent manner

BACKGROUND

Targeted increase in glucose uptake of ischemic myocardium is a potential therapeutic strategy for myocardial ischemia. PEDF presents a profound moderating effect on glucose metabolism of cells, but its role is still controversial. Here, we try to demonstrate the direct effect of PEDF on glucose uptake in ischemic myocyte and to elucidate its underlying mechanism.

METHODS AND RESULTS

Lentivirus vectors carrying PEDF gene were delivered into the myocardium to locally overexpress PEDF in a myocardial ischemia/reperfusion rat model. PET imaging showed that PEDF local overexpression increased [¹⁸F]-FDG uptake of ischemic myocardium. In vitro, PEDF directly increased the glucose uptake in hypoxic cardiomyocytes. The expression of glucose transporter 4 (GLUT4) on plasma membrane of hypoxic cardiomyocytes was significantly upregulated by PEDF, but its total amount was not changed. The increased glucose uptake and cardioprotective effects induced by PEDF were blocked by the GLUT4 inhibitor indinavir. PEDF-mediated GLUT4 translocation and glucose uptake increase in hypoxic cardiomyocytes were prevented by phosphatidyl-inositol-3 kinase (PI3K) inhibitor or AKT inhibitor. The PEDF-mediated glucose uptake was also diminished when PEDF receptor (PEDFR) was downregulated or potent phospholipase A2 enzymatic activity was inhibited.

CONCLUSIONS

PEDF can increase glucose uptake in ischemic myocardium through a PEDFR-dependent mechanism, involving PI3K/AKT signaling and GLUT4 translocation.

Atractylodesin III maintains mitochondrial function and inhibits caspase-3 activity to reverse apoptosis of cardiomyocytes in AMI rats

The aim of the present study was to analyze the effects of Atractylodesin III (codonopsis pilosula) extract that maintains mitochondrial function, up-regulates Bcl-2, inhibits Caspase-3 activity, and ultimately leads to cardiomyocyte apoptosis in a rat model of acute myocardial infarction (AMI). 30 male Sprague-Dawley rats aged 6 months, weighed 150-200 g were randomly divided into sham operation group (SOG), model group (MG) and intervention group (IG). The IG was intragastrically administered with atractylodesin III (30 mg/kg/d) for 7 days. The model group was treated with (30 mg/kg/d) of sterile saline. After 4.5 h, the heart samples from each group were taken, the myocardial infarct size was detected by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining.After ematoxylin & Eosin (HE) staining apoptosis indices were determined by Terminal deoxynucleotidyl transferase TdT-mediated dUTP Nick-End Labeling (TUNEL) method. Apoptosis-related genes and protein including Bcl-2, Bax, and Caspase-3 expression were determined by quantitative real time polymerase chain reaction (qRT-PCR) and western blot respectively. The infarct size and apoptotic index of the MG were significantly higher than SOG. However, infarct size and apoptotic index were reduced in IGcompared to MG (P < 0.05). The levels of Bax and Caspase-3 in the MG were significantly higher, while Bcl-2 and Bcl-2/Bax were lower than those in the SOG. The IG has lower levels of Bax and Caspase-3, higher levels of Bcl-2 and Bcl-2/Bax (P < 0.05) compared to MG. Atractylodesin III decreased apoptosis of myocardial cells in AMI, up-regulated Bcl-2 expression, and inhibited Bax and Caspase-3 activity.

Hypoxia-Inducible Factor 1 alpha (HIF-1α)/Vascular Endothelial Growth Factor (VEGF) Pathway Participates in Angiogenesis of Myocardial Infarction in Muscone-Treated Mice: Preliminary Study

BACKGROUND Angiogenesis plays a crucial role in myocardial infarction (MI) treatment by ameliorating myocardial remodeling, thus improving cardiac function and preventing heart failure. Muscone has been reported to have beneficial effects on cardiac remodeling in MI mice. However, the effects of muscone on angiogenesis in MI mice and its underlying mechanisms remain unknown. MATERIAL AND METHODS Mice were randomly divided into sham, MI, and MI+muscone groups. The MI mouse model was established by ligating the left anterior descending coronary artery. Mice in the sham group received the same procedure except for ligation. Mice were administered muscone or an equivalent volume of saline for 4 consecutive weeks. Cardiac function was evaluated by echocardiograph after MI for 2 and 4 weeks. Four weeks later, all mice were sacrificed and Masson's trichrome staining was used to assess myocardial fibrosis. Isolectin B4 staining was applied to evaluate the angiogenesis in mouse hearts. Immunohistochemistry, Western blot analysis, and quantitative real-time polymerase chain reaction (qPCR) were performed to analyze expression levels of HIF-1a and its downstream genes. RESULTS Compared with the MI group, muscone treatment significantly improved cardiac function and reduced myocardial fibrosis. Moreover, muscone enhanced angiogenesis in the peri-infarct region and p-VEGFR2 expression in the vascular endothelial cells. Western blot analysis and qPCR showed that muscone upregulated expression levels of HIF-1a and VEGFA. CONCLUSIONS Muscone improved cardiac function in MI mice through augmented angiogenesis. The potential mechanism of muscone treatment in regulating angiogenesis of MI mice was upregulating expression levels of HIF-1α and VEGFA.

Inhibition of MEK/ERK/STAT3 signaling in oleuropein treatment inhibits myocardial ischemia/reperfusion

Studies have shown that oleuropein has antifungal, anti‑inflammatory, antiviral, antioxidant, anticancer and hypoglycemic functions. TTC solution staining was used to measure myocardial infarction size. A commercial kit was used to measure lactate dehydrogenase (LDH), creatinine kinase‑MB (CK‑MB), tumor necrosis factor‑α (TNF‑α), interleukin‑1β (IL‑1β), IL 6, superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and catalase levels. Western blot analysis was used to measure p53, p-MEK p-ERK and p‑IκBα protein expression. The present study reports that the protective effect of oleuropein also prevents against myocardial ischemia/reperfusion (myocardial I/R). The aim of this retrospective study was to evaluate this protective effect of oleuropein and the mechanisms by which myocardial I/R is prevented. Oleuropein inhibited myocardial infarction size, CK‑MB and LDH serum levels in a myocardial I/R rat model. Moreover, oleuropein also attenuated caspase‑3 activity, and p53, phosphorylated (p)‑mitogen‑activated protein kinase kinase (MEK), p‑extracellular signal‑regulated protein kinase (ERK) and p‑IκBα protein expression. TNF‑α, IL‑1β, IL‑6 and MDA were decreased; SOD, GSH and catalase levels inhibited TNF‑α, IL‑1β, IL-6 and MDA levels, and increased SOD, GSH and catalase levels in myocardial I/R rats treated with oleuropein. Rats orally administered the MEK inhibitor PD0325901, in addition to oleuropein, exhibited inhibited myocardial infarction size, CK‑MB and LDH serum levels compared with rats treated with oleuropein only. Rats treated with MEK inhibitor also exhibited suppressed caspase‑3 activity, p53, p‑MEK p‑ERK and p‑IκBα protein expression, TNF‑α, IL‑1β, IL‑6, SOD, GSH, MDA and catalase levels, and induced p‑signal transducer and activator of transcription 3 (STAT3) protein expression compared with rats treated with oleuropein only. Taken together, these results suggest that MEK/ERK/STAT3 signaling regulates the inhibition of myocardial I/R in rats treated with oleuropein.

PEDF regulates lipid metabolism and reduces apoptosis in hypoxic H9c2 cells by inducing autophagy related 5-mediated autophagy via PEDF-R

Pigment epithelial-derived factor (PEDF) is a multifunctional secreted glycoprotein, which exerts a variety of physiological activities. PEDF may protect against hypoxia‑induced cell death associated with its antioxidative effects and p53 mitochondrial translocation in cultured cardiomyocytes and H9c2 cells. Additionally, previous studies have suggested that autophagy is an important cell survival mechanism. However, the effect of PEDF on autophagy and the associated pathway in hypoxic H9c2 cells has not been fully established. Autophagy has been reported to regulate lipid metabolism; however, little is known about whether PEDF is able to regulate lipid metabolism by promoting autophagy. In the present study, western blotting results revealed that PEDF increased the level of microtubule‑associated protein 1A/1B‑light chain 3 (LC3)‑II. Transmission electron microscopy (TEM) and LC3 fluorescence demonstrated that PEDF increased the number of autophagosomes. PEDF also increased the viability of hypoxic H9c2 cells and decreased the level of cleaved caspase‑3 protein, as evidenced by CCK‑8 assays and western blotting, respectively. TEM and a triglyceride assay kit demonstrated that PEDF‑induced autophagy may stimulate lipid degradation. Western blotting results revealed a novel mechanism underlying PEDF‑induced H9c2 cell autophagy via the PEDF‑R‑mediated Atg5 pathway under hypoxic conditions. Furthermore, the results also suggest that PEDF‑induced autophagy may stimulate lipid degradation. The survival function of autophagy suggests that modulation of PEDF‑induced autophagy may be used as a therapeutic strategy to protect cells against lipid-associated metabolic diseases.

PEDF improves cardiac function in rats subjected to myocardial ischemia/reperfusion injury by inhibiting ROS generation via PEDF‑R

The prevention and management of myocardial ischemia/reperfusion (MI/R) injury is an essential part of coronary heart disease surgery and is becoming a major clinical problem in the treatment of ischemic heart disease. Previous studies by our group have demonstrated that pigment epithelium-derived factor (PEDF) improves cardiac function in rats with acute myocardial infarction and reduces hypoxia-induced cell injury. However, the protective function and mechanisms underlying the effect of PEDF in MI/R injury remain to be fully understood. In the present study, the positive effect of PEDF in MI/R injury was confirmed by construction of the adult Sprague-Dawley rat MI/R model. PEDF reduced myocardial infarct size and downregulated cardiomyocyte apoptosis in the I/R myocardium in this model. In addition, PEDF improved cardiac function and increased cardiac functional reserve in rats subjected to MI/R Injury. To further study the protective effect of PEDF and the underlying mechanisms in MI/R injury, a H9c2 cardiomyocyte hypoxia/reoxygenation (H/R) model was constructed. PEDF was confirmed to decrease H/R-induced apoptosis in H9c2 cells, and this anti-apoptotic function was abolished by pigment epithelium-derived factor-receptor (PEDF R) small interfering (si)RNA. Furthermore, administration of PEDF decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in H/R H9c2 cells. Compared with the H/R group, PEDF decreased mitochondrial ROS, increased the mitochondrial DNA copy number, reduced xanthine oxidase and NADPH oxidase activity, as well as RAC family small GTPase 1 protein expression. However, these effects of PEDF were markedly attenuated by PEDF-R siRNA. To the best of our knowledge, the present study is the first to identify the protective effect of PEDF in MI/R injury, and confirm that the antioxidative effect PEDF occurred via inhibition of ROS generation via PEDF-R under MI/R conditions.

PEDF protects cardiomyocytes by promoting FUNDC1‑mediated mitophagy via PEDF-R under hypoxic condition

Pigment epithelial-derived factor (PEDF) is known to exert diverse physiological activities. Previous studies suggest that hypoxia could induce mitophagy. Astoundingly, under hypoxic condition, we found that PEDF decreased the mitochondrial density of cardiomyocytes. In this study, we evaluated whether PEDF could decrease the mitochondrial density and play a protective role in hypoxic cardiomyocytes via promoting mitophagy. Immunostaining and western blotting were used to analyze mitochondrial density and mitophagy of hypoxic cardiomyocytes. Gas chromatography-mass spectrometry and ELISA were used to analyze levels of palmitic acid and diacylglycerol. Transmission Electron Microscopy was used to detect mitophagy and the mitochondrial density in adult male Sprague-Dawley rat model of acute myocardial infarction. Compared to the control group, we observed that PEDF decreased mitochondrial density through promoting hypoxic cardiomyocyte mitophagy. PEDF increased the levels of palmitic acid and diacylglycerol, and then upregulated the levels of protein kinase Cα (PKC-α) and its activation. Furthermore, inhibition of PKC-α by Go6976 could effectively suppress PEDF-induced mitophagy. Besides, we found that PEDF promoted FUNDC1-mediated cardiomyocyte mitophagy via ULK1, which depended on the activation of PKC-α. Finally, we discovered that mitophagy was increased and mitochondrial density was reduced in adult male Sprague-Dawley rat model of acute myocardial infarction. We concluded that PEDF promotes mitophagy to protect hypoxic cardiomyocytes, through PEDF/PEDF-R/PA/DAG/PKC-α/ULK1/FUNDC1 pathway.

Cardioprotective effect of Notch signaling on the development of myocardial infarction complicated by diabetes mellitus

The present study aimed to elucidate the role of Notch signaling in the development of myocardial infarction (MI) concomitant with diabetes in vivo and in vitro and evaluated the therapeutic effect of the Notch signaling in vitro. Streptozotocin-induced diabetic rats were subjected to 25 min of ischemia and 2 h of reperfusion. Cardiac troponin T (cTnT) and creatine kinase-MB (CK-MB) isoenzyme levels were detected. Infarct size was measured by 2,3,5-triphenyltetrazolium chloride staining. Myocardial apoptosis and fibrosis were examined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and Masson Trichrome staining, respectively. The mRNA and protein levels of Notch signaling components, including Notch1, Notch4, Delta-like 1, Jagged1, Mastermind-like protein 1 and p300, were quantified by reverse transcription-quantitative polymerase chain reaction and western blotting analyses, respectively. H9c2 cells were treated with/without 33 mM high glucose (HG) and/or subjected to hypoxia in the presence/absence of Jagged1. Cell viability and apoptosis were determined by MTT assay and Annexin V-fluorescein isothiocyanate/propidium iodide assay. Levels of the Notch signaling pathway members were examined. The present findings revealed that diabetes elevated CK-MB and cTnT, increased infarct size, induced myocardial apoptosis and inhibited the Notch signaling pathway in vivo after ischemia/reperfusion. Ischemia/reperfusion augmented the severity of MI in diabetic rats. Furthermore, HG reduced cell viability and induced cell apoptosis in H9c2 cells after hypoxia exposure, which was inhibited by Jagged1. We also found that HG inhibited Notch signaling in H9c2 cells after hypoxia, whereas Jagged1 exerted its cardioprotective effect on hypoxic injury (in HG environments or not) by activating the Notch signaling pathway. In conclusion, these findings suggest that diabetes promoted the progression of MI in vivo and in vitro via the inhibition of the Notch signaling pathway. Jagged1 may protect against MI in in vitro models by activating Notch signaling.

A novel modified physiologically relevant model for cardiac angiogenesis

Angiogenesis assays are important tools for studying both the mechanisms of cardiac angiogenesis and the potential development of therapeutic strategies to ischemic heart diseases. Currently, various assays have been used to quantitate cardiac tubule formation, yet no consensus has been reached regarding a suitable assay for evaluating the efficacy of angiogenic stimulants or inhibitors. Most in vivo angiogenesis assays are complex and difficult to interpret, whereas traditional in vitro angiogenesis models measure only one aspect of this process. To bridge the gap between in vivo and in vitro angiogenesis assays, here, we have developed a novel modified cardiac explants matrigel assay. We observed the morphology of vascular sprouts formed in three forms of cardiac angiogenesis assays then used quantitative image analyses to further compare the morphological features of vascular sprouts formed in two cardiac explants angiogenesis assays. Vascular sprouts formed in the fibronectin group were less and short, whereas those formed in the matrigel group were significantly longer, consisting of more area and branch points. Moreover, we found the benefits of this matrigel model by observing the ability of cardiac explants to form vascular sprouts under normoxia or hypoxia condition in the presence of angiogenic stimulant and inhibitor, VEGF and PEDF. In summary, the above analyses revealed that the morphology of vascular sprouts formed in this model appears more representative of myocardial capillary formation in vivo, and this accessible, reliable angiogenic assay is a more physiologically relevant assay which allows further assessment of pharmacologic compounds on cardiac angiogenesis.

Pigment epithelium-derived factor attenuates myocardial fibrosis via inhibiting Endothelial-to-Mesenchymal Transition in rats with acute myocardial infarction

Endothelial mesenchymal transition (EndMT) plays a critical role in the pathogenesis and progression of interstitial and perivascular fibrosis after acute myocardial infarction (AMI). Pigment epithelium-derived factor (PEDF) is shown to be a new therapeutic target owing to its protective role in cardiovascular disease. In this study, we tested the hypothesis that PEDF is an endogenous inhibitor of EndMT and represented a novel mechanism for its protective effects against overactive cardiac fibrosis after AMI. Masson’s trichrome (MTC) staining and picrosirius red staining revealed decreased interstitial and perivascular fibrosis in rats overexpressing PEDF. The protective effect of PEDF against EndMT was confirmed by co-labeling of cells with the myofibroblast and endothelial cell markers. In the endothelial cells of microvessels in the ischemic myocardium, the inhibitory effect of PEDF against nuclear translocation of β-catenin was observed through confocal microscopic imaging. The correlation between antifibrotic effect of PEDF and inactivation of β-catenin was confirmed by co-transfecting cells with lentivirus carrying PEDF or PEDF RNAi and plasmids harboring β-catenin siRNA(r) or constitutive activation of mutant β-catenin. Taken together, these results establish a novel finding that PEDF could inhibit EndMT related cardiac fibrosis after AMI by a mechanism dependent on disruption of β-catenin activation and translocation.

PEDF Inhibits the Activation of NLRP3 Inflammasome in Hypoxia Cardiomyocytes through PEDF Receptor/Phospholipase A2

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome has been linked to sterile inflammation, which is involved in ischemic injury in myocardial cells. Pigment epithelium-derived factor (PEDF) is a multifunctional secreted glycoprotein with many biological activities, such as anti-inflammatory, antioxidant and anti-angiogenic properties. However, it is not known whether and how PEDF acts to regulate the activation of the NLRP3 inflammasome in cardiomyocytes. In the present study, we used the neonatal cardiomyocytes models of ischemia-like conditions to evaluate the mitochondrial fission and the activation of the NLRP3 inflammasome. We also determined the mechanism by which PEDF inhibits hypoxia-induced activation of the NLRP3 inflammasome. We found that PEDF decreased the activation of the NLRP3 inflammasome in neonatal cardiomyocytes through pigment epithelial-derived factor receptor/calcium-independent phospholipase A2 (PEDFR/iPLA2). Meanwhile, PEDF reduced Drp1-induced mitochondrial fission and mitochondrial fission-induced mitochondrial DNA (mtDNA), as well as mitochondrial reactive oxygen species (mtROS) release into cytosol through PEDFR/iPLA2. We also found that PEDF inhibited mitochondrial fission-induced NLRP3 inflammasome activation. Furthermore, previous research has found that endogenous cytosolic mtDNA and mtROS can serve as activators of NLRP3 inflammasome activity. Therefore, we hypothesized that PEDF can protect against hypoxia-induced activation of the NLRP3 inflammasome by inhibiting mitochondrial fission though PEDFR/iPLA2.

Pigment Epithelium-Derived Factor (PEDF) Improves Ischemic Cardiac Functional Reserve Through Decreasing Hypoxic Cardiomyocyte Contractility Through PEDF Receptor (PEDF-R)

BACKGROUND

Pigment epithelium-derived factor (PEDF), which belongs to the noninhibitory serpin family, has shown the ability to stimulate several physiological processes, such as antiangiogenesis, anti-inflammation, and antioxidation. In the present study, the effects of PEDF on contractility and calcium handling of rat ventricular myocytes were investigated.

METHODS AND RESULTS

Adult Sprague-Dawley rat models of acute myocardial infarction (AMI) were surgically established. PEDF-lentivirus was delivered into the myocardium along and away from the infarction border to overexpress PEDF. Video edge detection was used to measure myocyte shortening in vitro. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator, Fura-2-acetoxymethyl ester. PEDF local overexpression enhanced cardiac functional reserve in AMI rats and reduced myocardial contracture bordering the infracted area. Exogenous PEDF treatment (10 nmol/L) caused a significant decrease in amplitudes of isoproterenol-stimulated myocyte shortening, Ca(2+) transients, and caffeine-evoked Ca(2+) transients in vitro. We then tested a potential role for PEDF receptor-mediated effects on upregulation of protein kinase C (PKC) and found evidence of signaling through the diacylglycerol/PKCα pathway. We also confirmed that pretreatment of cardiomyocytes with PEDF exhibited dephosphorylation of phospholamban at Ser(16), which could be attenuated with PKC inhibition.

CONCLUSIONS

The results suggest that PEDF depresses myocyte contractility by suppressing phosphorylation of phospholamban and Ca(2+) transients in a PKCα-dependent manner through its receptor, PEDF receptor, therefore improving cardiac functional reserve during AMI.

Pigment Epithelium-Derived Factor Mediates Autophagy and Apoptosis in Myocardial Hypoxia/Reoxygenation Injury

Pigment epithelium-derived factor (PEDF) is a multifunctional protein that exhibits anti-angiogenic, antitumor, anti-inflammatory, antioxidative, anti-atherogenic, and cardioprotective properties. While it was recently shown that PEDF expression is inhibited under low oxygen conditions, the functional role of PEDF in response to hypoxia/reoxygenation (H/R) remains unclear. The goal of this study was to therefore investigate the influence of PEDF on myocardial H/R injury. For these analyses, PEDF-specific small interfering RNA-expressing and PEDF-expressing lentivirus (PEDF-LV) vectors were utilized to knockdown or stably overexpress PEDF, respectively, within human cardiomyocytes (HCM) in vitro. We noted that reactive oxygen species (ROS) play important roles in the induction of cell death pathways, including apoptosis and autophagy in ischemic hearts. Our findings demonstrate that overexpression of PEDF resulted in a significant reduction in ROS production and attenuation of mitochondrial membrane potential depletion under H/R conditions. Furthermore, PEDF inhibited the activation of a two-step apoptotic pathway in which caspase-dependent (caspase-9 and caspase-3) and caspase-independent (apoptosis inducing factor and endonuclease G), which in turn cleaves several crucial substrates including the DNA repair enzyme poly (ADP-ribose) polymerase. Meanwhile, overexpression of PEDF also promoted autophagy, a process that is typically activated in response to H/R. Therefore, these findings suggest that PEDF plays a critical role in preventing H/R injury by modulating anti-oxidant and anti-apoptotic factors and promoting autophagy.

Pigment Epithelium-Derived Factor (PEDF) Protects Osteoblastic Cell Line from Glucocorticoid-Induced Apoptosis via PEDF-R

Pigment epithelial-derived factor (PEDF) is known as a widely expressed multifunctional secreted glycoprotein whose biological actions are cell-type dependent. Recent studies demonstrated that PEDF displays cytoprotective activity in several cell types. However, it remains unknown whether PEDF is involved in glucocorticoid-induced osteoblast death. The aim of this study was to examine the role of PEDF in osteoblast survival in response to dexamethasone, an active glucocorticoid analogue, and explore the underlying mechanism. In the present study, dexamethasone (DEX) was used to induce MC3T3-E1 pre-osteoblast apoptosis. PEDF mRNA and protein levels and cell apoptosis were determined respectively. Then PEDF receptor (PEDF-R)- and lysophosphatidic acid (LPA)-related signal transductions were assessed. Here we show that DEX down-regulates PEDF expression, which contributes to osteoblast apoptosis. As a result, exogenous recombinant PEDF (rPEDF) inhibited DEX-induced cell apoptosis. We confirmed that PEDF-R was expressed on MC3T3-E1 pre-osteoblast membrane and could bind to PEDF which increased the level of LPA and activated the phosphorylation of Akt. Our results suggest that PEDF attenuated DEX-induced apoptosis in MC3T3-E1 pre-osteoblasts through LPA-dependent Akt activation via PEDF-R.

Cardioprotective effect of Salvianolic acid B on acute myocardial infarction by promoting autophagy and neovascularization and inhibiting apoptosis

OBJECTIVES

The aim of this study was to investigate the cardioprotective effect of salvianolic acid B (Sal B) on acute myocardial infarction (AMI) in rats and its potential mechanisms.

METHODS

The AMI model was established in rats to study the effect of Sal B on AMI. Haematoxylin-eosin (HE) staining was used to evaluate the pathological change in AMI rats. Immunofluorescence and TUNEL staining were used to detect autophagy and apoptosis of myocardial cells in hearts of AMI rats, respectively. Protein expression of apoptosis-related, autophagy-related and angiogenesis-related proteins were examined by Western blot.

KEY FINDINGS

Sal B attenuated myocardial infarction significantly compared with that of the model group. Rats administered with Sal B showed higher inhibition rate of infarction and lower infarct size than those of the model group. Moreover, Sal B decreased the serum levels of creatine kinase, lactate dehydrogenase and malondialdehyde, while increased such level of superoxide dismutase significantly compared with those of the model group. Sal B inhibited the expression of Bax, cleaved caspase-9 and cleaved PARP, while promoted the expression of Bcl-2, LC3-II, Beclin1 and VEGF.

CONCLUSIONS

Sal B has cardioprotective effect on AMI and Sal B may be a promising candidate for AMI treatment.

PEDF attenuates hypoxia-induced apoptosis and necrosis in H9c2 cells by inhibiting p53 mitochondrial translocation via PEDF-R

Pigment epithelial-derived factor (PEDF) is a multifunctional secreted glycoprotein, which could protect against hypoxia-induced cell death related to its anti-oxidative effect in cultured cardiomyocytes. However, the pathway mediating this cytoprotective process has not been fully established. Here we confirmed that PEDF bound to pigment epithelial-derived factor receptor (PEDF-R) expressed on the membrane of H9c2 cells. Under hypoxic condition, PEDF increased the ratio of MDM2:p53, so as to inhibited p53 mitochondrial translocation via PEDF-R. As a result, mitochondrial outer membrane permeabilization (MOMP) and mitochondrial permeability transition pore (MPTP) opening were inhibited, meanwhile cleaved caspase-3, PARP and the release of HMGB1 were reduced. Accordingly, apoptosis and necrosis were attenuated simultaneously. We conclude that PEDF-R mediates PEDF attenuates hypoxia-induced apoptosis and necrosis in H9c2 cells by inhibiting p53 mitochondrial translocation.