MicroRNAs (miRNAs) are a class of small single-stranded and highly conserved non-coding RNAs, which are closely linked to cardiac disorders such as myocardial infarction (MI), cardiomyocyte hypertrophy, and heart failure. A growing number of studies have demonstrated that miRNAs determine the fate of the heart by regulating cardiac cell death and regeneration after MI. A deep understanding of the pathophysiology of miRNA dependent regulatory pathways in these processes is required. The role of miRNAs as diagnostic, prognostic, and therapeutic targets also needs to be explored in order to utilize them in clinical settings. This review summarizes the role of miRNAs in myocardial infarction and focuses mainly on their influence on cardiomyocyte regeneration and cell death including apoptosis, necrosis, and autophagy. In addition, the targets of pro- and anti-MI miRNAs are comparatively described. In particular, the possibilities of miRNA-based diagnostic and therapeutic strategies for myocardial infarction are discussed in this review.

https://www.mdpi.com/1422-0067/18/4/745/pdf

The Role of MicroRNAs in Myocardial Infarction: From Molecular Mechanism to Clinical Application

Aims To assess the incidence, risk factors and prognosis of periprocedural myocardial infarction (MI) and myocardial injury in patients undergoing elective percutaneous coronary intervention (PCI). Methods and results We included all consecutive patients who underwent elective PCI with a negative troponin level at admission from 1 January 2014 to 31 December 2015. The primary endpoint was defined as the composite of periprocedural MI (Type 4a MI), stent thrombosis (Type 4b MI), and myocardial injury according to the Third universal definition of MI. Multivariable analysis was performed to identify independent predictors of periprocedural MI and myocardial injury and its relation to 30-day and 1-year clinical outcome. Of the 1390 elective PCI patients, the primary endpoint occurred in 28.7% of patients, including 7.0% of Type 4a MI, 0.14% of Type 4b MI, and 21.6% of myocardial injury. Independent risk factors for the occurrence of the primary endpoint were left main PCI, total stent length >30 mm, multiple stenting, chronic kidney disease (estimated glomerular filtration rate 75 years. At 30 days, patients with periprocedural MI and myocardial injury had a higher rate of cardiovascular events [5.5% vs. 1.2%, adjusted hazard ratio (adjHR) = 3.8, 95% confidence interval (CI) 1.9-6.9; P < 0.001] mainly driven by ischaemic events (3.2% vs. 0.6%, HR 5.9, 95% CI 2.9-20; P < 0.0001). At 1-year, the risk of ischemic events remained higher in the periprocedural MI and myocardial injury group (adjHR = 1.7, 95% CI 1.1-2.6; P = 0.004). Conclusions Periprocedural MI and injury are frequent complications of elective PCI associated with an increased rate of cardiovascular events at 30 days and 1 year.

/pdf/periprocedural-myocardial-infarction-and-injury-in-elective-48xq252moo.pdf

Periprocedural myocardial infarction and injury in elective coronary stenting.

Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these “non-classical” cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development. 

 

Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure.

https://www.tandfonline.com/doi/pdf/10.4161/org.24892

Autonomic cardiac innervation: development and adult plasticity.

The worldwide increase in the prevalence of Diabetes Mellitus has highlighted the need for increased research efforts into treatment options for both the disease itself and its associated complications. In recent years, Mesenchymal stromal cells (MSCs) have been highlighted as a new emerging regenerative therapy due to their multipotency but also due to their paracrine secretion of angiogenic factors, cytokines and immunomodulatory substances. This review focuses on the potential use of MSCs as a regenerative medicine in microvascular and secondary complications of Diabetes Mellitus and will discuss the challenges and future prospects of MSCs as a regenerative therapy in this field. MSCs are believed to have an important role in tissue repair. Evidence in recent years has demonstrated that MSCs have potent immunomodulatory functions resulting in active suppression of various components of the host immune response. MSCs may also have glucose lowering properties providing another attractive and unique feature of this therapeutic approach. Through a combination of the above characteristics MSCs have been shown to exert beneficial effects in preclinical models of diabetic complications prompting initial clinical studies in diabetic wound healing and nephropathy. Challenges that remain in the clinical translation of MSC therapy include issues of MSC heterogeneity, optimal mode of cell delivery, homing of these cells to tissues of interest with high efficiency, clinically meaningful engraftment, and challenges with cell manufacture. An issue of added importance is whether an autologous or allogeneic approach will be used. In summary, MSC administration has significant potential in the treatment of diabetic microvascular and secondary complications but challenges remain in terms of engraftment, persistence, tissue targeting and cell manufacture.

http://www.kumc.edu/Documents/msctc/Davey%20Front%20Endocrinol%20(Lausanne).%202014%20.pdf

Mesenchymal stem cell-based treatment for microvascular and secondary complications of diabetes mellitus.

Traumatic brain injury (TBI) is a serious medical and social problem worldwide. Because of the complex pathophysiological mechanisms of TBI, effective pharmacotherapy is still lacking. The microglial cells are resident tissue macrophages located in the brain and have two major polarization states, M1 phenotype and M2 phenotype, when activated. The M1 phenotype is related to the release of proinflammatory cytokines and secondary brain injury, while the M2 phenotype has been proved to be responsible for the release of anti-inflammation cytokines and for central nervous system (CNS) repair. In animal models, pharmacological strategies inhibiting the M1 phenotype and promoting the M2 phenotype of microglial cells could alleviate cerebral damage and improve neurological function recovery after TBI. In this review, we aimed to summarize the current knowledge about the pathological significance of microglial M1/M2 polarization in the pathophysiology of TBI. In addition, we reviewed several drugs that have provided neuroprotective effects against brain injury following TBI by altering the polarization states of the microglia. We emphasized that future investigation of the regulation mechanisms of microglial M1/M2 polarization in TBI is anticipated, which could contribute to the development of new targets of pharmacological intervention in TBI.

/pdf/the-polarization-states-of-microglia-in-tbi-a-new-paradigm-212jyyztxx.pdf

The Polarization States of Microglia in TBI: A New Paradigm for Pharmacological Intervention.

Inflammation-dominated sympathetic sprouting adjacent to the necrotic region following myocardial infarction (MI) has been implicated in the etiology of arrhythmias resulting in sudden cardiac death; however, the mechanisms responsible remain to be elucidated. Although being a key immune mediator, the role of Notch has yet to be explored. We investigated whether Notch regulates macrophage responses to inflammation and affects cardiac sympathetic reinnervation in rats undergoing MI. MI was induced by coronary artery ligation. A high level of Notch intracellular domain was observed in the macrophages that infiltrated the infarct area at 3 days post-MI. The administration of the Notch inhibitor N-N-(3,5-difluorophenacetyl-L-alanyl)-S-phenylglycine-t-butyl ester (DAPT) (intravenously 30 min before MI and then daily until death) decreased the number of macrophages and significantly increased the M2 macrophage activation profile in the early stages and attenuated the expression of nerve growth factor (NGF). Eventually, NGF-induced sympathetic hyperinnervation was blunted, as assessed by the immunofluorescence of tyrosine hydroxylase. At 7 days post-MI, the arrhythmia score of programmed electric stimulation in the vehicle-treated infarcted rats was higher than that in rats treated with DAPT. Further deterioration in cardiac function and decreases in the plasma levels of TNF-α and IL-1β were also detected. In vitro studies revealed that LPS/IFN-γ upregulated the surface expression of NGF in M1 macrophages in a Notch-dependent manner. We concluded that Notch inhibition during the acute inflammatory response phase is associated with the downregulation of NGF, probably through a macrophage-dependent pathway, thus preventing the process of sympathetic hyperinnervation.

https://www.physiology.org/doi/pdf/10.1152/ajpcell.00163.2015

Inhibition of Notch signaling pathway attenuates sympathetic hyperinnervation together with the augmentation of M2 macrophages in rats post-myocardial infarction

Nerve growth factor (NGF) is involved in nerve sprouting, hyper-innervation, angiogenesis, anti-apoptosis, and preservation of cardiac function after myocardial infarction (MI). Positively modulating NGF expression may represent a novel pharmacological strategy to improve post-infarction prognosis. In this study, lentivirus encoding NGF short interfering RNA (siRNA) was prepared, and MI was modeled in the rat using left anterior descending coronary artery ligation. Rats were randomly grouped to receive intramyocardial injection of lentiviral solution containing NGF-siRNA (n = 19, MI-SiNGF group), lentiviral solution containing empty vector (n = 18, MI-GFP group) or 0.9% NaCl solution (n = 18, MI-control group), or to receive thoracotomy and pericardiotomy (n = 17, sham-operated group). At 1, 2, 4, and 8 wk after transduction, rats in the MI-control group had higher levels of NGF mRNA and protein than those in the sham-operated group, rats in the MI-GFP group showed similar levels as the MI-control group, and rats in the MI-SiNGF group had lower levels compared to the MI-GFP group, indicating that MI model was successfully established and NGF siRNA effectively inhibited the expression of NGF. At 8 wk, echocardiographic and hemodynamic studies revealed a more severe cardiac dysfunction in the MI-siRNA group compared to the MI-GFP group. Moreover, rats in the MI-siRNA group had lower mRNA and protein expression levels of tyrosine hydroxylase (TH) and growth-associated protein 43-positive nerve fibers (GAP-43) at both the infarcted border and within the non-infarcted left ventricles (LV). NGF silencing also reduced the vascular endothelial growth factor (VEGF) expression and decreased the arteriolar and capillary densities at the infarcted border compared to the MI-GFP group. Histological analysis indicated a large infarcted size in the MI-SiNGF group. These findings suggested that endogenous NGF silencing attenuated sympathetic nerve sprouting and angiogenesis, enlarged the infarct size, aggravated cardiac dysfunction, and potentially contributed to an unfavorable prognosis after MI.

/pdf/targeted-ngf-sirna-delivery-attenuates-sympathetic-nerve-4zt4riguem.pdf

Targeted NGF siRNA Delivery Attenuates Sympathetic Nerve Sprouting and Deteriorates Cardiac Dysfunction in Rats with Myocardial Infarction

Background: Abnormal sympathetic innervation underlies both long-term hyperglycemia and myocardial infarction (MI). The incidence of ventricular arrhythmias (VAs) after MI is higher in diabetic than in nondiabetic patients. However, the exact mechanism remains unclear. In this study, we aimed to explore sympathetic neural remodeling after MI in diabetic rabbits and its relationship with VAs. Methods: Rabbits were randomly assigned to 4 groups: control, diabetes mellitus (DM), MI and diabetic myocardial infarction (DI). After electrophysiological experiments in vivo, immunohistochemistry and real-time RT-PCR were used to measure sympathetic innervations. To test the function of sympathetic nerve fibers, norepinephrine levels were measured by high-performance liquid chromatography. Results: The corrected QT interval and QT dispersion were significantly more prolonged with DI than other conditions. The density of tyrosine hydroxylase-positive fibers and corresponding mRNA abundance was significantly higher with DI than with DM and under control conditions, but was lower than with the MI group. Moreover, the distribution and structure of regenerated nerve was heterogeneous in DI rabbits. Norepinephrine content was higher in the DI group, and accompanied by an increased quantity of tyrosine hydroxylase-positive fibers. Conclusion: MI results in sympathetic neural remodeling in diabetic rabbits, which may be responsible in part for the increased occurrence of VAs.

Risk of ventricular arrhythmias after myocardial infarction with diabetes associated with sympathetic neural remodeling in rabbits.

To investigate the effects of semaphorin 3A (sema 3A) on cardiac autonomic regulation and subsequent ventricular arrhythmias (VAs) in post-infarcted hearts. In order to explore the functions of sema 3A in post-infarcted hearts, lentivirus-Sema 3A-shRNA and negative control vectors were delivered to the peri-infarcted myocardium rats respectively. Meanwhile, recombinant sema 3A and control (0.9 % NaCl solution) were injected intravenously into infarcted rats to test the therapeutic potential of sema 3A. Results indicated that levels of sema 3A were higher in post-infarcted hearts compared with sham rats. However, sema 3A silencing leaded to sympathetic hyperinnervation, increased myocardial norepinephrine (NE) content and inducible VAs. Conversely, the intravenous administration of sema 3A to infarcted rats reduced sympathetic nerve sprouting, improved cardiac autonomic regulation, and decreased the incidence of inducible VAs. However, both infarct size and cardiac function were similar among infarcted hearts. The upregulation and administration of sema 3A exerted beneficial effects on infarction-induced cardiac autonomic disorders by increasing cardiac electrical stability and reducing VAs. Sema 3A might be a potential therapeutic agent for cardiac autonomic abnormalities induced arrhythmias.

/pdf/semaphorin-3a-attenuates-cardiac-autonomic-disorders-and-j6gp2ctbju.pdf

Semaphorin 3A attenuates cardiac autonomic disorders and reduces inducible ventricular arrhythmias in rats with experimental myocardial infarction.

Objectives Inflammation after myocardial infarction (MI) causes cardiac nerve sprouting and consequent ventricular arrhythmias (VAs). Macrophages, as major immune cells, are involved in the entire inflammation response process and serve as a link between inflammation and sympathetic hyperinnervation by regulating nerve growth factor (NGF) expression. Accumulating evidence shows that statins possess antiarrhythmogenic properties, and the aim of this study was to explore the mechanism by which atorvastatin ameliorates cardiac sympathetic nerve sprouting via regulating macrophage polarization. Methods Rat models of MI were created by ligating the left coronary artery. MI-operated rats received either atorvastatin or phosphate-buffered saline for 7 days. Immunohistochemical analyses and immunofluorescence staining were used to analyze macrophage infiltration after MI and to detect the distribution and density of growth-associated protein-43 (GAP-43) and tyrosine hydroxylase (TH) in nerve fibers in peri-infarct zones after MI. The polarity of the macrophages that were obtained from the rat peritoneal cavity was examined via flow cytometry. The protein levels of NGF were detected via Western blot analysis, and the concentrations of NGF in the supernatants were determined via enzyme-linked immunosorbent assay. The mRNA levels of NGF, inducible nitric oxide synthase (iNOS), Arginase-1 (Arg1), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were examined by quantitative real-time polymerase chain reaction. The association between VAs and MI was evaluated using programmed electrophysiological stimulation. Results Macrophages were successfully induced to the M1 (classically activated) and M2 (alternatively activated) phenotypes by stimulation with lipopolysaccharide and interferon-γ (LPS + IFN-γ) and interleukin-4 (IL-4), respectively. Atorvastatin markedly downregulated IL-1β, TNF-α, iNOS, and NGF and upregulated Arg1, shifting the macrophage phenotype from M1 to M2. Moreover, atorvastatin significantly reduced TH levels and the density of GAP-43-positive nerve fibers and decreased inducible VAs. Conclusion Atorvastatin effectively ameliorated cardiac sympathetic nerve remodeling and prevented VAs after MI by significantly downregulating the expression of NGF, IL-1β, and TNF-α via together with the augmentation of M2 macrophage.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1755-5922.12193

Yongli Xuan

Papers

Inhibition of Notch signaling pathway attenuates sympathetic hyperinnervation together with the augmentation of M2 macrophages in rats post-myocardial infarction

Targeted NGF siRNA Delivery Attenuates Sympathetic Nerve Sprouting and Deteriorates Cardiac Dysfunction in Rats with Myocardial Infarction

Risk of ventricular arrhythmias after myocardial infarction with diabetes associated with sympathetic neural remodeling in rabbits.

Semaphorin 3A attenuates cardiac autonomic disorders and reduces inducible ventricular arrhythmias in rats with experimental myocardial infarction.

Atorvastatin attenuates sympathetic hyperinnervation together with the augmentation of M2 macrophages in rats postmyocardial infarction.