Past and present of beta arrestins: A new perspective on insulin secretion and effect

BACKGROUND

Beta arrestins had been known as intracellular adaptors that uncouple and inactivate the G protein-coupled receptors that they interact with. Their roles as signal initiators for some receptors have recently been recognized.

SCOPE OF REVIEW

In this review, we focused on their role in mediating metabolic modulation primarily in relation to insulin signaling. Commenced by the upstream receptor, they seem to act like intracellular hubs that divert the metabolic profile of the cell. The amount of metabolic substrates in circulation and their usage/deposition by tissues are controlled by the contribution of all systems in the organism. This control is enabled by the release of hormones such as insulin, glucagon and glucagon-like peptide-1. Intriguingly, some ligands -either agonists or antagonists-of different classes of receptors have preferential properties mediated by β arrestins. This is not surprizing considering that substrate supply and usage should parallel physiological function such as hormone release or muscle contraction.

MAJOR CONCLUSIONS

Available data indicate that β arrestins conduct the regulatory role in insulin secretion and action. They may be good candidates to target when the upstream signal demands the function that may compromise the cell. An example is carvedilol that is protective by preventing the stimulatory effects of excessive catecholamines, stimulates mitochondrial function and has preferential clinical outcomes in metabolic disorders.

Treatment with β-blocker nebivolol ameliorates oxidative stress and endothelial dysfunction in tenofovir-induced nephrotoxicity in rats

Background

Tenofovir disoproxil fumarate (TDF), a widely prescribed component in antiretroviral regimens, has been associated with nephrotoxicity. Nebivolol is a third generation selective β-1 adrenergic receptor blocker and may protect renal structure and function through the suppression of oxidative stress and enhancement of nitric oxide (NO) synthesis. We aimed to investigate whether nebivolol could be an effective therapeutic strategy to mitigate tenofovir-induced nephrotoxicity.

Methods

We allocated Wistar rats to four groups: control (C), received a standard diet for 30 days; NBV, received a standard diet for 30 days added with nebivolol (100 mg/kg food) in the last 15 days; TDF, received a standard diet added with tenofovir (300 mg/kg food) for 30 days; and TDF+NBV, received a standard diet added with tenofovir for 30 days and nebivolol in the last 15 days.

Results

Long-term exposure to tenofovir led to impaired renal function, induced hypertension, endothelial dysfunction and oxidative stress. Nebivolol treatment partially recovered glomerular filtration rate, improved renal injury, normalized blood pressure and attenuated renal vasoconstriction. Administration of nebivolol contributed to reductions in asymmetric dimethylarginine (ADMA) levels as well as increases in endothelial nitric oxide sintase (eNOS) accompanied by renin-angiotensin-aldosterone system downregulation and decreases in macrophage and T-cells infiltrate. Furthermore, nebivolol was responsible for the maintenance of the adequate balance of thiobarbituric acid reactive substances (TBARS) and glutathione (GSH) levels and it was associated with reductions in NADPH oxidase (NOX) subunits.

Conclusion

Nebivolol holds multifaceted actions that promote an advantageous option to slow the progression of kidney injury in tenofovir-induced nephrotoxicity.

Use of disease-modifying drugs in diabetic patients with heart failure with reduced ejection fraction

Type 2 diabetes mellitus and heart failure are closely related, patients with type 2 diabetes mellitus have a higher risk of developing heart failure, and those with heart failure are at increased risk of developing type 2 diabetes. Although no specific randomized clinical trials have been conducted to test the effect of cardiovascular therapies (drugs and/or devices) in diabetic patients with heart failure, a lot of evidence shows that all interventions effective in improving prognosis in patients with heart failure reduced ejection fraction are equally beneficial in patients with and without diabetes. However, the use of disease-modifying drugs in patients with diabetes and heart failure reduced ejection fraction is a clinical challenge due to the increased risk of adverse effects. For example, β-blockers are underutilized in diabetic patients due to the theoretical unfavorable effects on glucose metabolism as well as the use of drugs that interact with the renin-angiotensin system can be challenged in patients with diabetic nephropathy because of the risk of hyperkalemia. This review outlines the current use of disease-modifying drugs in diabetic patients with heart failure reduced ejection fraction. In addition, the role of novel pharmacologic agents as type 2 sodium-glucose co-transporter inhibitors (SGLT2ii) is discussed.

State of the art approach to managing angina and ischemia: tailoring treatment to the evidence

Stable angina represents a chronic and often debilitating condition that affects daily activities and quality of life in patients with chronic coronary syndromes (CCS). Current European Society of Cardiology guidelines recommend a four-step approach for the medical treatment of patients taking into consideration hemodynamic variables (heart rate and blood pressure) and the presence or absence of left ventricular dysfunction. However, CCS patients often have several comorbidities and risk factors. Thus, a tailored approach that takes into consideration patient risk factors and comorbidities may have additional benefits beyond angina relief. This is a state of the art review of stable angina treatment based on the currently available evidence.

Efficacy and Safety of Nebivolol and Rosuvastatin Combination Treatment in Patients with Concomitant Hypertension and Hyperlipidemia

PURPOSE

We evaluated the efficacy and safety of nebivolol and rosuvastatin combination treatment in patients with hypertension and hyperlipidemia.

PATIENTS AND METHODS

Eligible patients, after more than 4 weeks of therapeutic lifestyle change, were randomly assigned to three groups: 5 mg nebivolol plus 20 mg rosuvastatin (NEBI/RSV), 20 mg rosuvastatin (RSV), or 5 mg nebivolol (NEBI). Treatments lasted 8 weeks.

RESULTS

Efficacy was analyzed using data from 276 patients. Sitting systolic and diastolic blood pressures differed between the NEBI/RSV and RSV groups (LSmean difference = -5.89 and -5.99 mmHg; 95% confidence interval [CI] = -9.88 to -1.90 mmHg and -8.13 to -3.84 mmHg, respectively). Reductions in the two pressures did not differ between the NEB/RSV and NEB groups. The percent reduction in low-density lipoprotein (LDL) cholesterol differed between the NEBI/RSV and NEBI groups (LSmean difference = -47.76%, 95% CI = -52.69 to -42.84%) but not between the NEBI/RSV and RSV groups. The blood pressure (BP) control rate was higher in the NEBI/RSV group than in the RVS group (51.09% vs 29.67%, p = 0.003). The LDL cholesterol goal achievement rate was higher in the NEBI/RSV group than in the NEBI group (85.87% vs 11.83%, p < 0.001). The incidence of adverse drug reactions in the NEBI/RSV, RSV, and NEBI groups was 8.51%, 7.45%, and 8.60%, respectively (p = 0.950).

CONCLUSION

Nebivolol plus rosuvastatin treatment is effective in reducing BP and LDL cholesterol levels and is safe in patients with hypertension and hypercholesterolemia without the loss of BP or the LDL cholesterol-lowering effect of each drug.

TRIAL REGISTRATION

CRIS registration number KCT0002148.

Potential off-target effects of beta-blockers on gut hormone receptors: In silico study including GUT-DOCK-A web service for small-molecule docking

The prolonged use of many currently available drugs results in the severe side effect of the disruption of glucose metabolism leading to type 2 diabetes mellitus (T2DM. Gut hormone receptors including glucagon receptor (GCGR) and the incretin hormone receptors: glucagon-like peptide 1 receptor (GLP1R) and gastric inhibitory polypeptide receptor (GIPR) are important drug targets for the treatment of T2DM, as they play roles in the regulation of glucose and insulin levels and of food intake. In this study, we hypothesized that we could compensate for the negative influences of specific drugs on glucose metabolism by the positive incretin effect enhanced by the off-target interactions with incretin GPCR receptors. As a test case, we chose to examine beta-blockers because beta-adrenergic receptors and incretin receptors are expressed in a similar location, making off-target interactions possible. The binding affinity of drugs for incretin receptors was approximated by using two docking scoring functions of Autodock VINA (GUT-DOCK) and Glide (Schrodinger) and juxtaposing these values with the medical information on drug-induced T2DM. We observed that beta-blockers with the highest theoretical binding affinities for gut hormone receptors were reported as the least harmful to glucose homeostasis in clinical trials. Notably, a recently discovered beta-blocker compound 15 ([4-((2S)-3-(((S)-3-(3-bromophenyl)-1-(methylamino)-1-oxopropan-2-yl)amino)-2-(2-cyclohexyl-2-phenylacetamido)-3-oxopropyl)benzamide was among the top-scoring drugs, potentially supporting its use in the treatment of hypertension in diabetic patients. Our recently developed web service GUT-DOCK (gut-dock.miningmembrane.com) allows for the execution of similar studies for any drug-like molecule. Specifically, users can compute the binding affinities for various class B GPCRs, gut hormone receptors, VIPR1 and PAC1R.

Differential Metabolic Effects of Beta-Blockers: an Updated Systematic Review of Nebivolol

Blood pressure management in hypertensive patients with metabolic abnormalities is challenging, since many of the antihypertensive drugs adversely affect metabolism. Besides effective control of blood pressure in patients with hypertension, third-generation beta-blockers such as nebivolol offer additional benefits for central hemodynamics and neutral or beneficial effects on metabolism. Emerging clinical data suggest that nebivolol also has similar effects on metabolism in obese hypertensive and hypertensive diabetic patients. The present article will provide a systematic analysis of the pathophysiological links among hypertension, insulin resistance, and metabolic syndrome. We will also summarize the available clinical evidence regarding the metabolic effects of beta-blockers in hypertensive patients, with an emphasis on nebivolol. Nebivolol exerts neutral or beneficial effects on insulin sensitivity and lipid metabolism in hypertensive patients, owing to its nitric oxide-mediated vasodilatory and antioxidative properties. Thus, nebivolol could be a favorable therapeutic option for the treatment of hypertension in patients with impaired glucose and lipid metabolism.

Perivascular adipose tissue as a regulator of vascular disease pathogenesis: identifying novel therapeutic targets

Adipose tissue (AT) is an active endocrine organ with the ability to dynamically secrete a wide range of adipocytokines. Importantly, its secretory profile is altered in various cardiovascular disease states. AT surrounding vessels, or perivascular AT (PVAT), is recognized in particular as an important local regulator of vascular function and dysfunction. Specifically, PVAT has the ability to sense vascular paracrine signals and respond by secreting a variety of vasoactive adipocytokines. Due to the crucial role of PVAT in regulating many aspects of vascular biology, it may constitute a novel therapeutic target for the prevention and treatment of vascular disease pathogenesis. Signalling pathways in PVAT, such as those using adiponectin, H₂ S, glucagon-like peptide 1 or pro-inflammatory cytokines, are among the potential novel pharmacological therapeutic targets of PVAT.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.