MicroRNA-16-5p Aggravates Myocardial Infarction Injury by Targeting the Expression of Insulin Receptor Substrates 1 and Mediating Myocardial Apoptosis and Angiogenesis

PURPOSE

Myocardial infarction is a common cardiovascular disease. MicroRNA-16-5p (miR-16-5p) was upregulated in heart and kidney hypoxia/reoxygenation (H/R) injury. However, the role of miR-16-5p in myocardial infarction injury is still unclear.

METHODS

Human adult ventricular cardiomyocytes (AC16) were treated with ischemia/reperfusion (H/R). The miR-16-5p level was evaluated through real-time PCR. The activity of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) was detected via LDH and CK-MB monitoring kits. Cell viability was examined with 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetra-zolium bromide (MTT) assay. Western blotting was used to analyze the protein levels. The luci-ferase report assay confirmed the relative luciferase activity.

RESULTS

miR-16-5p was elevated in H/R-treated AC16 cells. miR-16-5p overexpression and knockdown were carried out. miR-16-5p knockdown repressed cell apoptosis, attenuated LDH and CK-MB activities, and enhanced cell viability in H/R-treated AC16 cells. Moreover, miR-16-5p knockdown promoted angiogenesis in human microvascular endothelial cells (HMVEC), causing elevation of vascular endothelial growth factor (VEGF), insulin receptor substrates 1 (IRS1), minichromosome maintenance complex component 2 (MCM2) and proliferating cell nuclear antigen (PCNA) protein levels. Moreover, miR-16-5p was testified to target IRS1. IRS1 silencing alleviated miR-16-5p knockdown-mediated inhibition of apoptosis in AC16 cells.

CONCLUSION

miR-16-5p knockdown increased cell viability and angiogenesis, as well as inhibited cell apoptosis by increasing IRS1. These findings indicated that miR-16-5p knockdown may be a new therapeutic target for myocardial infarction.

Updated Understanding of Platelets in Thrombosis and Hemostasis: The Roles of Integrin PSI Domains and their Potential as Therapeutic Targets

Platelets are small blood cells known primarily for their ability to adhere and aggregate at injured vessels to arrest bleeding. However, when triggered under pathological conditions, the same adaptive mechanism of platelet adhesion and aggregation may cause thrombosis, a primary cause of heart attack and stroke. Over recent decades, research has made considerable progress in uncovering the intricate and dynamic interactions that regulate these processes. Integrins are heterodimeric cell surface receptors expressed on all metazoan cells that facilitate cell adhesion, movement, and signaling, to drive biological and pathological processes such as thrombosis and hemostasis. Recently, our group discovered that the plexin-semaphorin-integrin (PSI) domains of the integrin β subunits exert endogenous thiol isomerase activity derived from their two highly conserved CXXC active site motifs. Given the importance of redox reactions in integrin activation and its location in the knee region, this PSI domain activity may be critically involved in facilitating the interconversions between integrin conformations. Our monoclonal antibodies against the β3 PSI domain inhibited its thiol isomerase activity and proportionally attenuated fibrinogen binding and platelet aggregation. Notably, these antibodies inhibited thrombosis without significantly impairing hemostasis or causing platelet clearance. In this review, we will update mechanisms of thrombosis and hemostasis, including platelet versatilities and immune-mediated thrombocytopenia, discuss critical contributions of the newly discovered PSI domain thiol isomerase activity, and its potential as a novel target for anti-thrombotic therapies and beyond.

The Role of PCSK9 in the Pathogenesis of Non-alcoholic Fatty Liver Disease and the Effect of PCSK9 Inhibitors

BACKGROUND

Statin treatment exhibits a beneficial effect on non-alcoholic fatty liver disease (NAFLD) and on cardiovascular disease (CVD) in patients with NAFLD.

OBJECTIVE

The aim of this review is to summarize the role of proprotein convertase subtilisin kexin type- 9(PCSK9) in the pathogenesis of NAFLD and discuss the effects of the new hypolipidaemic drugs PCSK9 inhibitors on NAFLD.

RESULTS

Data indicates that high intrahepatic or circulating PCSK9 levels increase muscle and liver lipid storage, adipose energy storage and hepatic fatty acids, as well as triglycerides storage and secretion, thus contributing to the pathogenesis of NAFLD. The findings of animal and human studies, aiming to reduce PCSK9 with inhibitors (human IGG antibodies, antisense particles against PCSK9 mRNA, and small anti PCSK9 antibodies) point towards liver protection from NAFLD through inhibition of PCSK9 expression in the induction of degradation of hepatic HNF1a protein, insulin resistance (IR), and other mechanisms.

CONCLUSIONS

The use of PCSK9 inhibitors ameliorates NAFLD, aside from beneficial effects on CVD and independently of low density lipoprotein cholesterol level reduction.

Biological Consequences of Dysfunctional HDL

Epidemiological studies have suggested an inverse correlation between high-density lipoprotein (HDL) cholesterol levels and the risk of cardiovascular disease. HDLs promote reverse cholesterol transport (RCT) and possess several putative atheroprotective functions, associated to the anti-inflammatory, anti-thrombotic and anti-oxidant properties as well as to the ability to support endothelial physiology. The assumption that increasing HDL-C levels would be beneficial on cardiovascular disease (CVD), however, has been questioned as, in most clinical trials, HDL-C-raising therapies did not result in improved cardiovascular outcomes. These findings, together with the observations from Mendelian randomization studies showing that polymorphisms mainly or solely associated with increased HDL-C levels did not decrease the risk of myocardial infarction, shift the focus from HDL-C levels toward HDL functional properties. Indeed, HDL from atherosclerotic patients not only exhibit impaired atheroprotective functions but also acquire pro-atherogenic properties and are referred to as "dysfunctional" HDL; this occurs even in the presence of normal or elevated HDL-C levels. Pharmacological approaches aimed at restoring HDL functions may therefore impact more significantly on CVD outcome than drugs used so far to increase HDL-C levels. The aim of this review is to discuss the pathological conditions leading to the formation of dysfunctional HDL and their role in atherosclerosis and beyond.

The Co-Existence of NASH and Chronic Kidney Disease Boosts Cardiovascular Risk: Are there any Common Therapeutic Options?

Non-alcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease. NAFLD may evolve to non-alcoholic steatohepatitis (NASH), which is causally related to cirrhosis and cardiovascular disease (CVD) mortality. There is no generally accepted effective treatment for NAFLD/NASH. Chronic kidney disease (CKD) is relatively common and might co-exist with NAFLD/NASH, aggravate one another, and increase CVD risk. Common therapies could improve outcome. Potent statins at high doses, such as atorvastatin and rosuvastatin, ameliorate NAFLD/NASH and reduce the mortality rates by half as compared with those on the same statins but without liver disease and CVD-related events are reduced by atorvastatin for patients with all stages of CKD. The new anti-diabetic medication classes, the sodium-glucose co-transporter-2 inhibitors (SGLT2i) and the glucagon like peptide receptor agonists (GLP1 RA) for patients with NAFLD/NASH, CKD and T2DM are useful because they ameliorate NAFLD/NASH, delay the evolution of CKD, and substantially reduce CVD and all-cause mortality. Thus, the common use of high potency statins, renin-angiotensin-aldosterone system inhibitors, and the newer anti-diabetic agents increase compliance and can substantially reduce CVD risk and the rate of liver and kidney adverse events, improving quality of life and survival.

Benefits of SGLT2 Inhibitors Beyond Glycemic Control - A Focus on Metabolic, Cardiovascular and Renal Outcomes

BACKGROUND

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are a new pharmacotherapeutic class for the treatment of Type 2 Diabetes Mellitus (T2DM).

OBJECTIVE

To evaluate beneficial effects of the SGLT2 inhibitors on metabolic, cardiovascular, and renal outcomes.

METHODS

A Pub-Med search (1966 to July 2017) was performed of published English articles using keywords sodium-glucose co-transporter 2 inhibitors, canagliflozin, dapagliflozin, and empagliflozin. A review of literature citations provided further references. The search identified 17 clinical trials and 2 meta-analyses with outcomes of weight loss and blood pressure reduction with dapagliflozin, canagliflozin, or empagliflozin. Three randomized trials focused on either empagliflozin or canagliflozin and reduction of cardiovascular disease and progression of renal disease.

RESULTS

SGLT2 inhibitors have a beneficial profile in the treatment of T2DM. They have evidence of reducing weight between 2.9 kilograms when used as monotherapy to 4.7 kilograms when used in combination with metformin, and reducing systolic blood pressure between 3 to 5 mmHg and reducing diastolic blood pressure approximately 2 mmHg. To date, reduction of cardiovascular events was seen specifically with empagliflozin in patients with T2DM and a history of cardiovascular disease. In the same population, empagliflozin was associated with slowing the progression of kidney disease. Moreover, patients with increased risk of cardiovascular disease treated with canagliflozin have decreased risk of death from cardiovascular causes, nonfatal MI, or nonfatal stroke. Data regarding these outcomes with dapagliflozin are underway.

CONCLUSION

SGLT2 inhibitors demonstrate some positive metabolic effects. In addition, empagliflozin specifically has demonstrated reduction in cardiovascular events and delay in the progression of kidney disease in patients with T2DM and a history of cardiovascular disease. Further data is needed to assess if this is a class effect.